The Experts below are selected from a list of 2412 Experts worldwide ranked by ideXlab platform

Sharon Shacham - One of the best experts on this subject based on the ideXlab platform.

  • Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression.
    Oncotarget, 2018
    Co-Authors: Amro Aboukameel, Irfana Muqbil, William Senapedis, Erkan Baloglu, Yosef Landesman, Michael Kauffman, Trinayan Kashyap, Christian Argueta, Hua Chang, Sharon Shacham
    Abstract:

    Emerging studies have shown that the expression of AR splice variants (ARv) lacking ligand-binding domain is associated with castrate-resistant prostate cancer (CRPC) and higher risk of tumor metastasis and recurrence. Nuclear export protein XPO1 regulates the nuclear localization of many proteins including tumor suppressor proteins. Increased XPO1 in prostate cancer is associated with a high Gleason score and bone metastasis. In this study, we found that high expression of AR splice variant 7 (AR-v7) was correlated with increased XPO1 expression. Silencing of XPO1 by RNAi or treatment with Selective Inhibitor of Nuclear Export (SINE) compounds selinexor and eltanexor (KPT-8602) down-regulated the expression of AR, AR-v7 and ARv567es at mRNA and protein levels. XPO1 silencing also inhibited the expression of AR and ARv regulators including FOXA1, Src, Vav3, MED1 and Sam68, leading to the suppression of ARv and AR target genes, UBE2C and PSA. By targeting XPO1/ARv signaling, SINE suppressed prostate cancer (PCa) growth in vitro and in vivo and potentiated the anti-cancer activity of anti-AR agents, enzalutamide and abiraterone. Therefore, XPO1 inhibition could be a novel promising agent used in combination with conventional chemotherapeutics and AR-targeted therapy for the better treatment of PCa, especially CRPC.

  • Abstract 2492: Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression
    Molecular and Cellular Biology Genetics, 2018
    Co-Authors: Irfana Muqbil, William Senapedis, Erkan Baloglu, Yosef Landesman, Michael Kauffman, Christian Argueta, Hua Chang, Sharon Friedlander, Sharon Shacham
    Abstract:

    Increased XPO1 (a key nuclear exporter of many tumor suppressor proteins [TSPs]) expression in prostate cancer (PCa) has been found to be associated with a high Gleason score and bone metastasis. However, it is unknown whether aberrant XPO1 activity regulates AR and AR splice variants (Arv) signaling in PCa progression. In this study, using 22Rv1 and VCaP prostate cancer cells which harbor full length AR and ARv, we conduct in vitro cellular and molecular biological experiments and in vivo animal studies to elucidate the role XPO1 inhibition plays in PCa progression through regulation of XPO1/AR/ARv signaling. We found that high expression of AR splice variant 7 (AR-v7) was correlated with increased XPO1 expression. Silencing of XPO1 by RNAi or treatment with Selective Inhibitor of Nuclear Export (SINE) compounds (selinexor and KPT-8602/eltanexor) down-regulated the expression of AR, AR-v7 and ARv567es at the mRNA and protein levels. Mechanistic studies showed that XPO1 silencing also inhibited the expression of AR/ARv regulators including FOXA1, Src, Vav3, MED1 and Sam68, leading to the suppression of ARv and AR target genes, UBE2C and PSA. SINE compound treatment of cells retained the eIF4E protein (translation initiation factor and nuclear transporter of capped depended mRNAs) in nuclear compartment, leading to nuclear retention of AR-v7 and PSA mRNAs. The nuclear localization of AR-v7 mRNA resulted in the reduction in the ARv protein. Furthermore, SINE compound treatment retained TSPs including Rb, p21, p53, APC and SMAD4 in the nucleus leading to inhibition of cell proliferation and induction of apoptosis. Moreover, by targeting XPO1/ARv signaling, SINE compounds suppressed prostate cancer growth in vitro and in vivo and potentiated the anti-cancer activity of conventional chemotherapeutic agent docetaxel and anti-AR agents (enzalutamide and abiraterone) through the inhibition of AR, AR-v7, FOXA1, PSA and UBE2C. From these results, we conclude that there is a causal relationship between XPO1 and AR splice variants. High expression of both XPO1 and AR-v7 could lead to constitutively activated AR signaling, CRPC development and progression, and anti-AR drug resistance. By targeting XPO1/AR/ARv signaling and increasing anti-AR sensitivity, SINE compounds could be novel agents used in combination with conventional chemotherapeutics and AR-targeted therapy for the treatment of PCa, especially CRPC. Citation Format: Irfana Muqbil, Yiwei Li, Erkan Baloglu, William Senapedis, Yosef Landesman, Christian Argueta, Michael Kauffman, Sharon Friedlander, Hua Chang, Sharon Shacham, Elisabeth Heath, Asfar S. Azmi. Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2492.

  • Abstract 2491: Nuclear exporter protein XPO1 a novel prognostic and therapeutic target in gastric cancer
    Molecular and Cellular Biology Genetics, 2018
    Co-Authors: Irfana Muqbil, William Senapedis, Erkan Baloglu, Sharon Shacham, Yosef Landesman, Michael Kauffman, Zaid Mahdi, Rahman Choudhary, Steve Kim, Rafic Beydoun
    Abstract:

    The high mortality rate associated with Gastric Cancer (GC) indicates the urgent need for actionable therapeutic targets. The nuclear exporter protein exportin 1 (XPO1/CRM1) is the exclusive exporter of many tumor suppressor proteins (TPSs) and growth regulators. XPO1 is often over-expressed in different malignancies leading to aberrant cytoplasmic localization of TSPs and subsequent inactivation. A detailed analysis on the correlation of XPO1 with inflammation-metaplasia-dysplasia-carcinoma sequence progression was performed using immunohistochemistry in 70 GC cases: (a) 10 cases from normal gastric mucosa, (b) 10 cases of stomach with intestinal metaplasia with and without inflammation, (c) 10 cases of mucosa with low-grade dysplasia (d) 10 cases of mucosa with high-grade dysplasia, (e) 10 cases of gastric adenocarcinoma and (f) 20 cases of metastatic gastric carcinoma. A correlation between XPO1 expression, the pathological and clinical features of the disease as well as survival were analyzed. Gastric cancer cell lines were exposed to the Selective Inhibitors of Nuclear Export (SINE) compounds (selinexor, KPT-8602, KPT-185, or the natural agent, leptomycin B (LMB), then analyzed using cytotoxicity and molecular assays. In addition, the activity of selinexor was evaluated in a sub-cutaneous xenograft of gastric cancer cell line NCI-N87. XPO1 served as a prognostic marker for poor outcome as positive staining of XPO1 in GC correlated with aggressive behavior of the disease. Targeting XPO1 using SINE compounds or LMB resulted in inhibition of GC cellular growth (IC50 Citation Format: Irfana Muqbil, Zaid Mahdi, Rahman Choudhary, Erkan Baloglu, William Senapedis, Yosef Landesman, Sharon Shacham, Michael Kauffman, Steve Kim, Rafic Beydoun, Richard N. Berri, Anthony Shields, Ramzi M. Mohammad, Asfar S. Azmi. Nuclear exporter protein XPO1 a novel prognostic and therapeutic target in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2491.

  • XPO1 target occupancy measurements confirm the selinexor recommended phase 2 dose
    Oncotarget, 2017
    Co-Authors: Marsha Crochiere, Erkan Baloglu, Sharon Shacham, Michael Kauffman, Stefan Hannus, Kerrin Hansen, Frank Becker, Margaret S. Lee, Yosef Landesman
    Abstract:

    XPO1 (exportin 1) is the main nuclear export protein with over 200 different protein cargos. XPO1 is overexpressed in tumor cells and high levels are correlated with poor prognosis. Selective Inhibitor of Nuclear Export (SINE) compounds block nuclear export by inhibiting XPO1. The first SINE compound, selinexor, shows promising anti-cancer activity across hematological and solid tumors in Phase 2 and 3 clinical trials. The 2nd generation SINE compound KPT-8602 is being evaluated as an anti-cancer agent in a Phase 1 clinical trial. To predict patient response to treatment and confirm the selinexor recommended phase 2 dose (RP2D), an assay based on fluorescence cross correlation spectroscopy that measures XPO1 occupancy in cancer cells was developed. Studies comparing cytotoxicity and XPO1 occupancy in cell lines treated with selinexor or KPT-8602 indicated that XPO1 occupancy by both compounds could reach saturation regardless of drug sensitivity. However, higher levels of XPO1 protein correlated with lower sensitivity to SINE compound cytotoxicity. In vivo mouse studies showed XPO1 occupancy could be measured in tumors and was dose-dependent, with >90% target saturation at 10 mg/kg (∼50 mg flat dose in humans). Drug-target occupancy was measured in a dose-response time course and full occupancy occurred by 6 hours at all doses. The duration of occupancy was dose-dependent, where 10-15 mg/kg in mice (∼ 50-75 mg human flat dose) was necessary to maintain XPO1 occupancy up to 48 hours post-dose. These findings confirm the selinexor RP2D of 60 mg for achieving target occupancy and inhibition up to 48 hours.

  • Abstract 464: Novel role of XPO1 in regulating MicroRNAs related to pancreatic ductal adenocarcinoma invasion and metastasis
    Molecular and Cellular Biology Genetics, 2017
    Co-Authors: Asfar S. Azmi, Irfana Muqbil, William Senapedis, Erkan Baloglu, Sharon Shacham, Yosef Landesman, Michael Kauffman, Amro Aboukameel, Philip A. Philip
    Abstract:

    Objective: There are no known reports on the role of exportin 1 (XPO1; also known as chromosome maintenance region 1 [CRM1]) in microRNA biology. In this study, we for the first time demonstrate that interfering with XPO1 machinery can influence miRNA signaling leading to suppression of pancreatic ductal adenocarcinoma (PDAC) proliferation, invasion and metastasis. Methods: miRNA arrays (LCSciences, Houston, TX) were performed on total RNA samples from PDAC cell lines (HPAC, MiaPaCa-2, AsPc-1 and L3.6pl) and normal human pancreatic ductal epithelial (HPDE) cells. PDAC cells were treated with XPO1 inhibitor (Selinexor) or transfected with control siRNA, XPO1 siRNA (Santa Cruz), miR-control or miR-145 mimic (Applied biosystems) all at a final concentration of 20 nM using DharmaFact Transfection Reagent (Dharmacon, Lafayette. CO). The total RNA and total protein from treated or transfected cells were subjected to real-time PCR or immunoblot analysis in order to measure expression level of miR-145, let-7d, miR-34c, miR-320, miR-205, and miR-145 target or downstream genes including EGFR, MMP1, MT-MMP, c-Myc, Sox-2, and PAK4. The impact of XPO1 inhibitor Selinexor on PDAC growth, proliferation, invasion and migrations was also evaluated using MTT and scratch assay. Results: In this study, we show that PDAC cells have significantly reduced expression of miR-145 when compared to normal pancreatic duct epithelial cells. Similarly, forced expression of miR-145 in PDAC cells inhibited cell proliferation and migration. Conversely, we demonstrate that RNAi of XPO1 by siRNA knockdown or chemical inhibition of XPO1 by selective inhibitor of nuclear export compound (Selinexor) restores miR-145 expression in PDAC cells ultimately leading to inhibition of cell proliferation and migration. In addition, we show that the inhibition of cell proliferation and migration by Selinexor is mediated through the down-regulation of known miR-145 signals including EGFR, MMP1, MT-MMP, c-Myc, PAK4 and Sox-2. Selinexor also induced the expression of two important tumor suppressive miRNAs, miR-34c and let-7d, leading to the up-regulation of p21WAF1. We also observed the down-regulation of oncomir mir-205. Conclusions: These results are the first to show that targeted inhibition of the nuclear exporter protein XPO1 by RNAi or Selinexor could restore tumor suppressive miRs in PDAC. Citation Format: Asfar S. Azmi, Yiwei Li, Irfana Muqbil, Amro Aboukameel, William Senapedis, Erkan Baloglu, Yosef Landesman, Michael Kauffman, Sharon Shacham, Philip A. Philip, Ramzi M. Mohammad. Novel role of XPO1 in regulating MicroRNAs related to pancreatic ductal adenocarcinoma invasion and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 464. doi:10.1158/1538-7445.AM2017-464

Yosef Landesman - One of the best experts on this subject based on the ideXlab platform.

  • Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression.
    Oncotarget, 2018
    Co-Authors: Amro Aboukameel, Irfana Muqbil, William Senapedis, Erkan Baloglu, Yosef Landesman, Michael Kauffman, Trinayan Kashyap, Christian Argueta, Hua Chang, Sharon Shacham
    Abstract:

    Emerging studies have shown that the expression of AR splice variants (ARv) lacking ligand-binding domain is associated with castrate-resistant prostate cancer (CRPC) and higher risk of tumor metastasis and recurrence. Nuclear export protein XPO1 regulates the nuclear localization of many proteins including tumor suppressor proteins. Increased XPO1 in prostate cancer is associated with a high Gleason score and bone metastasis. In this study, we found that high expression of AR splice variant 7 (AR-v7) was correlated with increased XPO1 expression. Silencing of XPO1 by RNAi or treatment with Selective Inhibitor of Nuclear Export (SINE) compounds selinexor and eltanexor (KPT-8602) down-regulated the expression of AR, AR-v7 and ARv567es at mRNA and protein levels. XPO1 silencing also inhibited the expression of AR and ARv regulators including FOXA1, Src, Vav3, MED1 and Sam68, leading to the suppression of ARv and AR target genes, UBE2C and PSA. By targeting XPO1/ARv signaling, SINE suppressed prostate cancer (PCa) growth in vitro and in vivo and potentiated the anti-cancer activity of anti-AR agents, enzalutamide and abiraterone. Therefore, XPO1 inhibition could be a novel promising agent used in combination with conventional chemotherapeutics and AR-targeted therapy for the better treatment of PCa, especially CRPC.

  • Abstract 2492: Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression
    Molecular and Cellular Biology Genetics, 2018
    Co-Authors: Irfana Muqbil, William Senapedis, Erkan Baloglu, Yosef Landesman, Michael Kauffman, Christian Argueta, Hua Chang, Sharon Friedlander, Sharon Shacham
    Abstract:

    Increased XPO1 (a key nuclear exporter of many tumor suppressor proteins [TSPs]) expression in prostate cancer (PCa) has been found to be associated with a high Gleason score and bone metastasis. However, it is unknown whether aberrant XPO1 activity regulates AR and AR splice variants (Arv) signaling in PCa progression. In this study, using 22Rv1 and VCaP prostate cancer cells which harbor full length AR and ARv, we conduct in vitro cellular and molecular biological experiments and in vivo animal studies to elucidate the role XPO1 inhibition plays in PCa progression through regulation of XPO1/AR/ARv signaling. We found that high expression of AR splice variant 7 (AR-v7) was correlated with increased XPO1 expression. Silencing of XPO1 by RNAi or treatment with Selective Inhibitor of Nuclear Export (SINE) compounds (selinexor and KPT-8602/eltanexor) down-regulated the expression of AR, AR-v7 and ARv567es at the mRNA and protein levels. Mechanistic studies showed that XPO1 silencing also inhibited the expression of AR/ARv regulators including FOXA1, Src, Vav3, MED1 and Sam68, leading to the suppression of ARv and AR target genes, UBE2C and PSA. SINE compound treatment of cells retained the eIF4E protein (translation initiation factor and nuclear transporter of capped depended mRNAs) in nuclear compartment, leading to nuclear retention of AR-v7 and PSA mRNAs. The nuclear localization of AR-v7 mRNA resulted in the reduction in the ARv protein. Furthermore, SINE compound treatment retained TSPs including Rb, p21, p53, APC and SMAD4 in the nucleus leading to inhibition of cell proliferation and induction of apoptosis. Moreover, by targeting XPO1/ARv signaling, SINE compounds suppressed prostate cancer growth in vitro and in vivo and potentiated the anti-cancer activity of conventional chemotherapeutic agent docetaxel and anti-AR agents (enzalutamide and abiraterone) through the inhibition of AR, AR-v7, FOXA1, PSA and UBE2C. From these results, we conclude that there is a causal relationship between XPO1 and AR splice variants. High expression of both XPO1 and AR-v7 could lead to constitutively activated AR signaling, CRPC development and progression, and anti-AR drug resistance. By targeting XPO1/AR/ARv signaling and increasing anti-AR sensitivity, SINE compounds could be novel agents used in combination with conventional chemotherapeutics and AR-targeted therapy for the treatment of PCa, especially CRPC. Citation Format: Irfana Muqbil, Yiwei Li, Erkan Baloglu, William Senapedis, Yosef Landesman, Christian Argueta, Michael Kauffman, Sharon Friedlander, Hua Chang, Sharon Shacham, Elisabeth Heath, Asfar S. Azmi. Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2492.

  • Abstract 2491: Nuclear exporter protein XPO1 a novel prognostic and therapeutic target in gastric cancer
    Molecular and Cellular Biology Genetics, 2018
    Co-Authors: Irfana Muqbil, William Senapedis, Erkan Baloglu, Sharon Shacham, Yosef Landesman, Michael Kauffman, Zaid Mahdi, Rahman Choudhary, Steve Kim, Rafic Beydoun
    Abstract:

    The high mortality rate associated with Gastric Cancer (GC) indicates the urgent need for actionable therapeutic targets. The nuclear exporter protein exportin 1 (XPO1/CRM1) is the exclusive exporter of many tumor suppressor proteins (TPSs) and growth regulators. XPO1 is often over-expressed in different malignancies leading to aberrant cytoplasmic localization of TSPs and subsequent inactivation. A detailed analysis on the correlation of XPO1 with inflammation-metaplasia-dysplasia-carcinoma sequence progression was performed using immunohistochemistry in 70 GC cases: (a) 10 cases from normal gastric mucosa, (b) 10 cases of stomach with intestinal metaplasia with and without inflammation, (c) 10 cases of mucosa with low-grade dysplasia (d) 10 cases of mucosa with high-grade dysplasia, (e) 10 cases of gastric adenocarcinoma and (f) 20 cases of metastatic gastric carcinoma. A correlation between XPO1 expression, the pathological and clinical features of the disease as well as survival were analyzed. Gastric cancer cell lines were exposed to the Selective Inhibitors of Nuclear Export (SINE) compounds (selinexor, KPT-8602, KPT-185, or the natural agent, leptomycin B (LMB), then analyzed using cytotoxicity and molecular assays. In addition, the activity of selinexor was evaluated in a sub-cutaneous xenograft of gastric cancer cell line NCI-N87. XPO1 served as a prognostic marker for poor outcome as positive staining of XPO1 in GC correlated with aggressive behavior of the disease. Targeting XPO1 using SINE compounds or LMB resulted in inhibition of GC cellular growth (IC50 Citation Format: Irfana Muqbil, Zaid Mahdi, Rahman Choudhary, Erkan Baloglu, William Senapedis, Yosef Landesman, Sharon Shacham, Michael Kauffman, Steve Kim, Rafic Beydoun, Richard N. Berri, Anthony Shields, Ramzi M. Mohammad, Asfar S. Azmi. Nuclear exporter protein XPO1 a novel prognostic and therapeutic target in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2491.

  • XPO1 target occupancy measurements confirm the selinexor recommended phase 2 dose
    Oncotarget, 2017
    Co-Authors: Marsha Crochiere, Erkan Baloglu, Sharon Shacham, Michael Kauffman, Stefan Hannus, Kerrin Hansen, Frank Becker, Margaret S. Lee, Yosef Landesman
    Abstract:

    XPO1 (exportin 1) is the main nuclear export protein with over 200 different protein cargos. XPO1 is overexpressed in tumor cells and high levels are correlated with poor prognosis. Selective Inhibitor of Nuclear Export (SINE) compounds block nuclear export by inhibiting XPO1. The first SINE compound, selinexor, shows promising anti-cancer activity across hematological and solid tumors in Phase 2 and 3 clinical trials. The 2nd generation SINE compound KPT-8602 is being evaluated as an anti-cancer agent in a Phase 1 clinical trial. To predict patient response to treatment and confirm the selinexor recommended phase 2 dose (RP2D), an assay based on fluorescence cross correlation spectroscopy that measures XPO1 occupancy in cancer cells was developed. Studies comparing cytotoxicity and XPO1 occupancy in cell lines treated with selinexor or KPT-8602 indicated that XPO1 occupancy by both compounds could reach saturation regardless of drug sensitivity. However, higher levels of XPO1 protein correlated with lower sensitivity to SINE compound cytotoxicity. In vivo mouse studies showed XPO1 occupancy could be measured in tumors and was dose-dependent, with >90% target saturation at 10 mg/kg (∼50 mg flat dose in humans). Drug-target occupancy was measured in a dose-response time course and full occupancy occurred by 6 hours at all doses. The duration of occupancy was dose-dependent, where 10-15 mg/kg in mice (∼ 50-75 mg human flat dose) was necessary to maintain XPO1 occupancy up to 48 hours post-dose. These findings confirm the selinexor RP2D of 60 mg for achieving target occupancy and inhibition up to 48 hours.

  • Abstract 464: Novel role of XPO1 in regulating MicroRNAs related to pancreatic ductal adenocarcinoma invasion and metastasis
    Molecular and Cellular Biology Genetics, 2017
    Co-Authors: Asfar S. Azmi, Irfana Muqbil, William Senapedis, Erkan Baloglu, Sharon Shacham, Yosef Landesman, Michael Kauffman, Amro Aboukameel, Philip A. Philip
    Abstract:

    Objective: There are no known reports on the role of exportin 1 (XPO1; also known as chromosome maintenance region 1 [CRM1]) in microRNA biology. In this study, we for the first time demonstrate that interfering with XPO1 machinery can influence miRNA signaling leading to suppression of pancreatic ductal adenocarcinoma (PDAC) proliferation, invasion and metastasis. Methods: miRNA arrays (LCSciences, Houston, TX) were performed on total RNA samples from PDAC cell lines (HPAC, MiaPaCa-2, AsPc-1 and L3.6pl) and normal human pancreatic ductal epithelial (HPDE) cells. PDAC cells were treated with XPO1 inhibitor (Selinexor) or transfected with control siRNA, XPO1 siRNA (Santa Cruz), miR-control or miR-145 mimic (Applied biosystems) all at a final concentration of 20 nM using DharmaFact Transfection Reagent (Dharmacon, Lafayette. CO). The total RNA and total protein from treated or transfected cells were subjected to real-time PCR or immunoblot analysis in order to measure expression level of miR-145, let-7d, miR-34c, miR-320, miR-205, and miR-145 target or downstream genes including EGFR, MMP1, MT-MMP, c-Myc, Sox-2, and PAK4. The impact of XPO1 inhibitor Selinexor on PDAC growth, proliferation, invasion and migrations was also evaluated using MTT and scratch assay. Results: In this study, we show that PDAC cells have significantly reduced expression of miR-145 when compared to normal pancreatic duct epithelial cells. Similarly, forced expression of miR-145 in PDAC cells inhibited cell proliferation and migration. Conversely, we demonstrate that RNAi of XPO1 by siRNA knockdown or chemical inhibition of XPO1 by selective inhibitor of nuclear export compound (Selinexor) restores miR-145 expression in PDAC cells ultimately leading to inhibition of cell proliferation and migration. In addition, we show that the inhibition of cell proliferation and migration by Selinexor is mediated through the down-regulation of known miR-145 signals including EGFR, MMP1, MT-MMP, c-Myc, PAK4 and Sox-2. Selinexor also induced the expression of two important tumor suppressive miRNAs, miR-34c and let-7d, leading to the up-regulation of p21WAF1. We also observed the down-regulation of oncomir mir-205. Conclusions: These results are the first to show that targeted inhibition of the nuclear exporter protein XPO1 by RNAi or Selinexor could restore tumor suppressive miRs in PDAC. Citation Format: Asfar S. Azmi, Yiwei Li, Irfana Muqbil, Amro Aboukameel, William Senapedis, Erkan Baloglu, Yosef Landesman, Michael Kauffman, Sharon Shacham, Philip A. Philip, Ramzi M. Mohammad. Novel role of XPO1 in regulating MicroRNAs related to pancreatic ductal adenocarcinoma invasion and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 464. doi:10.1158/1538-7445.AM2017-464

Erkan Baloglu - One of the best experts on this subject based on the ideXlab platform.

  • Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression.
    Oncotarget, 2018
    Co-Authors: Amro Aboukameel, Irfana Muqbil, William Senapedis, Erkan Baloglu, Yosef Landesman, Michael Kauffman, Trinayan Kashyap, Christian Argueta, Hua Chang, Sharon Shacham
    Abstract:

    Emerging studies have shown that the expression of AR splice variants (ARv) lacking ligand-binding domain is associated with castrate-resistant prostate cancer (CRPC) and higher risk of tumor metastasis and recurrence. Nuclear export protein XPO1 regulates the nuclear localization of many proteins including tumor suppressor proteins. Increased XPO1 in prostate cancer is associated with a high Gleason score and bone metastasis. In this study, we found that high expression of AR splice variant 7 (AR-v7) was correlated with increased XPO1 expression. Silencing of XPO1 by RNAi or treatment with Selective Inhibitor of Nuclear Export (SINE) compounds selinexor and eltanexor (KPT-8602) down-regulated the expression of AR, AR-v7 and ARv567es at mRNA and protein levels. XPO1 silencing also inhibited the expression of AR and ARv regulators including FOXA1, Src, Vav3, MED1 and Sam68, leading to the suppression of ARv and AR target genes, UBE2C and PSA. By targeting XPO1/ARv signaling, SINE suppressed prostate cancer (PCa) growth in vitro and in vivo and potentiated the anti-cancer activity of anti-AR agents, enzalutamide and abiraterone. Therefore, XPO1 inhibition could be a novel promising agent used in combination with conventional chemotherapeutics and AR-targeted therapy for the better treatment of PCa, especially CRPC.

  • Abstract 2492: Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression
    Molecular and Cellular Biology Genetics, 2018
    Co-Authors: Irfana Muqbil, William Senapedis, Erkan Baloglu, Yosef Landesman, Michael Kauffman, Christian Argueta, Hua Chang, Sharon Friedlander, Sharon Shacham
    Abstract:

    Increased XPO1 (a key nuclear exporter of many tumor suppressor proteins [TSPs]) expression in prostate cancer (PCa) has been found to be associated with a high Gleason score and bone metastasis. However, it is unknown whether aberrant XPO1 activity regulates AR and AR splice variants (Arv) signaling in PCa progression. In this study, using 22Rv1 and VCaP prostate cancer cells which harbor full length AR and ARv, we conduct in vitro cellular and molecular biological experiments and in vivo animal studies to elucidate the role XPO1 inhibition plays in PCa progression through regulation of XPO1/AR/ARv signaling. We found that high expression of AR splice variant 7 (AR-v7) was correlated with increased XPO1 expression. Silencing of XPO1 by RNAi or treatment with Selective Inhibitor of Nuclear Export (SINE) compounds (selinexor and KPT-8602/eltanexor) down-regulated the expression of AR, AR-v7 and ARv567es at the mRNA and protein levels. Mechanistic studies showed that XPO1 silencing also inhibited the expression of AR/ARv regulators including FOXA1, Src, Vav3, MED1 and Sam68, leading to the suppression of ARv and AR target genes, UBE2C and PSA. SINE compound treatment of cells retained the eIF4E protein (translation initiation factor and nuclear transporter of capped depended mRNAs) in nuclear compartment, leading to nuclear retention of AR-v7 and PSA mRNAs. The nuclear localization of AR-v7 mRNA resulted in the reduction in the ARv protein. Furthermore, SINE compound treatment retained TSPs including Rb, p21, p53, APC and SMAD4 in the nucleus leading to inhibition of cell proliferation and induction of apoptosis. Moreover, by targeting XPO1/ARv signaling, SINE compounds suppressed prostate cancer growth in vitro and in vivo and potentiated the anti-cancer activity of conventional chemotherapeutic agent docetaxel and anti-AR agents (enzalutamide and abiraterone) through the inhibition of AR, AR-v7, FOXA1, PSA and UBE2C. From these results, we conclude that there is a causal relationship between XPO1 and AR splice variants. High expression of both XPO1 and AR-v7 could lead to constitutively activated AR signaling, CRPC development and progression, and anti-AR drug resistance. By targeting XPO1/AR/ARv signaling and increasing anti-AR sensitivity, SINE compounds could be novel agents used in combination with conventional chemotherapeutics and AR-targeted therapy for the treatment of PCa, especially CRPC. Citation Format: Irfana Muqbil, Yiwei Li, Erkan Baloglu, William Senapedis, Yosef Landesman, Christian Argueta, Michael Kauffman, Sharon Friedlander, Hua Chang, Sharon Shacham, Elisabeth Heath, Asfar S. Azmi. Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2492.

  • Abstract 2491: Nuclear exporter protein XPO1 a novel prognostic and therapeutic target in gastric cancer
    Molecular and Cellular Biology Genetics, 2018
    Co-Authors: Irfana Muqbil, William Senapedis, Erkan Baloglu, Sharon Shacham, Yosef Landesman, Michael Kauffman, Zaid Mahdi, Rahman Choudhary, Steve Kim, Rafic Beydoun
    Abstract:

    The high mortality rate associated with Gastric Cancer (GC) indicates the urgent need for actionable therapeutic targets. The nuclear exporter protein exportin 1 (XPO1/CRM1) is the exclusive exporter of many tumor suppressor proteins (TPSs) and growth regulators. XPO1 is often over-expressed in different malignancies leading to aberrant cytoplasmic localization of TSPs and subsequent inactivation. A detailed analysis on the correlation of XPO1 with inflammation-metaplasia-dysplasia-carcinoma sequence progression was performed using immunohistochemistry in 70 GC cases: (a) 10 cases from normal gastric mucosa, (b) 10 cases of stomach with intestinal metaplasia with and without inflammation, (c) 10 cases of mucosa with low-grade dysplasia (d) 10 cases of mucosa with high-grade dysplasia, (e) 10 cases of gastric adenocarcinoma and (f) 20 cases of metastatic gastric carcinoma. A correlation between XPO1 expression, the pathological and clinical features of the disease as well as survival were analyzed. Gastric cancer cell lines were exposed to the Selective Inhibitors of Nuclear Export (SINE) compounds (selinexor, KPT-8602, KPT-185, or the natural agent, leptomycin B (LMB), then analyzed using cytotoxicity and molecular assays. In addition, the activity of selinexor was evaluated in a sub-cutaneous xenograft of gastric cancer cell line NCI-N87. XPO1 served as a prognostic marker for poor outcome as positive staining of XPO1 in GC correlated with aggressive behavior of the disease. Targeting XPO1 using SINE compounds or LMB resulted in inhibition of GC cellular growth (IC50 Citation Format: Irfana Muqbil, Zaid Mahdi, Rahman Choudhary, Erkan Baloglu, William Senapedis, Yosef Landesman, Sharon Shacham, Michael Kauffman, Steve Kim, Rafic Beydoun, Richard N. Berri, Anthony Shields, Ramzi M. Mohammad, Asfar S. Azmi. Nuclear exporter protein XPO1 a novel prognostic and therapeutic target in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2491.

  • clinical implications of targeting XPO1 mediated nuclear export in multiple myeloma
    Clinical Lymphoma Myeloma & Leukemia, 2018
    Co-Authors: Ujjawal H Gandhi, William Senapedis, Erkan Baloglu, Thaddeus J Unger, Ajai Chari, Dan T Vogl, Robert F Cornell
    Abstract:

    Abstract Multiple myeloma (MM) is a malignancy of plasma cells that is typically chronic, and relapse is common. Current therapeutic strategies include combination and sequential treatments with corticosteroids, alkylating agents, proteasomal inhibitors, immunomodulators, and monoclonal antibodies. These drugs prolong survival but ultimately become ineffective. Exportin 1 (XPO1), a nuclear export protein, is overexpressed in MM cells, and knockdown studies have suggested that XPO1 is essential for MM cell survival. Selective inhibitor of nuclear export (SINE) compounds are novel, orally bioavailable class of agents that specifically inhibit XPO1. Selinexor (KPT-330) is the first-in-human SINE compound. Early phase clinical trials have established the safety profile of this agent and have shown promising efficacy in combination with low-dose dexamethasone and other anti-MM agents. The combination of selinexor and dexamethasone has demonstrated activity in "penta-refractory" MM, (ie, MM refractory to the 5 most active anti-MM agents currently used in treatment). We have reviewed the available data on the molecular implications of XPO1 inhibition in MM. We also reviewed the pertinent early phase clinical data with SINE compounds and discuss management strategies for common toxicities encountered with use of selinexor.

  • XPO1 target occupancy measurements confirm the selinexor recommended phase 2 dose
    Oncotarget, 2017
    Co-Authors: Marsha Crochiere, Erkan Baloglu, Sharon Shacham, Michael Kauffman, Stefan Hannus, Kerrin Hansen, Frank Becker, Margaret S. Lee, Yosef Landesman
    Abstract:

    XPO1 (exportin 1) is the main nuclear export protein with over 200 different protein cargos. XPO1 is overexpressed in tumor cells and high levels are correlated with poor prognosis. Selective Inhibitor of Nuclear Export (SINE) compounds block nuclear export by inhibiting XPO1. The first SINE compound, selinexor, shows promising anti-cancer activity across hematological and solid tumors in Phase 2 and 3 clinical trials. The 2nd generation SINE compound KPT-8602 is being evaluated as an anti-cancer agent in a Phase 1 clinical trial. To predict patient response to treatment and confirm the selinexor recommended phase 2 dose (RP2D), an assay based on fluorescence cross correlation spectroscopy that measures XPO1 occupancy in cancer cells was developed. Studies comparing cytotoxicity and XPO1 occupancy in cell lines treated with selinexor or KPT-8602 indicated that XPO1 occupancy by both compounds could reach saturation regardless of drug sensitivity. However, higher levels of XPO1 protein correlated with lower sensitivity to SINE compound cytotoxicity. In vivo mouse studies showed XPO1 occupancy could be measured in tumors and was dose-dependent, with >90% target saturation at 10 mg/kg (∼50 mg flat dose in humans). Drug-target occupancy was measured in a dose-response time course and full occupancy occurred by 6 hours at all doses. The duration of occupancy was dose-dependent, where 10-15 mg/kg in mice (∼ 50-75 mg human flat dose) was necessary to maintain XPO1 occupancy up to 48 hours post-dose. These findings confirm the selinexor RP2D of 60 mg for achieving target occupancy and inhibition up to 48 hours.

Michael Kauffman - One of the best experts on this subject based on the ideXlab platform.

  • Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression.
    Oncotarget, 2018
    Co-Authors: Amro Aboukameel, Irfana Muqbil, William Senapedis, Erkan Baloglu, Yosef Landesman, Michael Kauffman, Trinayan Kashyap, Christian Argueta, Hua Chang, Sharon Shacham
    Abstract:

    Emerging studies have shown that the expression of AR splice variants (ARv) lacking ligand-binding domain is associated with castrate-resistant prostate cancer (CRPC) and higher risk of tumor metastasis and recurrence. Nuclear export protein XPO1 regulates the nuclear localization of many proteins including tumor suppressor proteins. Increased XPO1 in prostate cancer is associated with a high Gleason score and bone metastasis. In this study, we found that high expression of AR splice variant 7 (AR-v7) was correlated with increased XPO1 expression. Silencing of XPO1 by RNAi or treatment with Selective Inhibitor of Nuclear Export (SINE) compounds selinexor and eltanexor (KPT-8602) down-regulated the expression of AR, AR-v7 and ARv567es at mRNA and protein levels. XPO1 silencing also inhibited the expression of AR and ARv regulators including FOXA1, Src, Vav3, MED1 and Sam68, leading to the suppression of ARv and AR target genes, UBE2C and PSA. By targeting XPO1/ARv signaling, SINE suppressed prostate cancer (PCa) growth in vitro and in vivo and potentiated the anti-cancer activity of anti-AR agents, enzalutamide and abiraterone. Therefore, XPO1 inhibition could be a novel promising agent used in combination with conventional chemotherapeutics and AR-targeted therapy for the better treatment of PCa, especially CRPC.

  • Abstract 2492: Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression
    Molecular and Cellular Biology Genetics, 2018
    Co-Authors: Irfana Muqbil, William Senapedis, Erkan Baloglu, Yosef Landesman, Michael Kauffman, Christian Argueta, Hua Chang, Sharon Friedlander, Sharon Shacham
    Abstract:

    Increased XPO1 (a key nuclear exporter of many tumor suppressor proteins [TSPs]) expression in prostate cancer (PCa) has been found to be associated with a high Gleason score and bone metastasis. However, it is unknown whether aberrant XPO1 activity regulates AR and AR splice variants (Arv) signaling in PCa progression. In this study, using 22Rv1 and VCaP prostate cancer cells which harbor full length AR and ARv, we conduct in vitro cellular and molecular biological experiments and in vivo animal studies to elucidate the role XPO1 inhibition plays in PCa progression through regulation of XPO1/AR/ARv signaling. We found that high expression of AR splice variant 7 (AR-v7) was correlated with increased XPO1 expression. Silencing of XPO1 by RNAi or treatment with Selective Inhibitor of Nuclear Export (SINE) compounds (selinexor and KPT-8602/eltanexor) down-regulated the expression of AR, AR-v7 and ARv567es at the mRNA and protein levels. Mechanistic studies showed that XPO1 silencing also inhibited the expression of AR/ARv regulators including FOXA1, Src, Vav3, MED1 and Sam68, leading to the suppression of ARv and AR target genes, UBE2C and PSA. SINE compound treatment of cells retained the eIF4E protein (translation initiation factor and nuclear transporter of capped depended mRNAs) in nuclear compartment, leading to nuclear retention of AR-v7 and PSA mRNAs. The nuclear localization of AR-v7 mRNA resulted in the reduction in the ARv protein. Furthermore, SINE compound treatment retained TSPs including Rb, p21, p53, APC and SMAD4 in the nucleus leading to inhibition of cell proliferation and induction of apoptosis. Moreover, by targeting XPO1/ARv signaling, SINE compounds suppressed prostate cancer growth in vitro and in vivo and potentiated the anti-cancer activity of conventional chemotherapeutic agent docetaxel and anti-AR agents (enzalutamide and abiraterone) through the inhibition of AR, AR-v7, FOXA1, PSA and UBE2C. From these results, we conclude that there is a causal relationship between XPO1 and AR splice variants. High expression of both XPO1 and AR-v7 could lead to constitutively activated AR signaling, CRPC development and progression, and anti-AR drug resistance. By targeting XPO1/AR/ARv signaling and increasing anti-AR sensitivity, SINE compounds could be novel agents used in combination with conventional chemotherapeutics and AR-targeted therapy for the treatment of PCa, especially CRPC. Citation Format: Irfana Muqbil, Yiwei Li, Erkan Baloglu, William Senapedis, Yosef Landesman, Christian Argueta, Michael Kauffman, Sharon Friedlander, Hua Chang, Sharon Shacham, Elisabeth Heath, Asfar S. Azmi. Down-regulation of AR splice variants through XPO1 suppression contributes to the inhibition of prostate cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2492.

  • Abstract 2491: Nuclear exporter protein XPO1 a novel prognostic and therapeutic target in gastric cancer
    Molecular and Cellular Biology Genetics, 2018
    Co-Authors: Irfana Muqbil, William Senapedis, Erkan Baloglu, Sharon Shacham, Yosef Landesman, Michael Kauffman, Zaid Mahdi, Rahman Choudhary, Steve Kim, Rafic Beydoun
    Abstract:

    The high mortality rate associated with Gastric Cancer (GC) indicates the urgent need for actionable therapeutic targets. The nuclear exporter protein exportin 1 (XPO1/CRM1) is the exclusive exporter of many tumor suppressor proteins (TPSs) and growth regulators. XPO1 is often over-expressed in different malignancies leading to aberrant cytoplasmic localization of TSPs and subsequent inactivation. A detailed analysis on the correlation of XPO1 with inflammation-metaplasia-dysplasia-carcinoma sequence progression was performed using immunohistochemistry in 70 GC cases: (a) 10 cases from normal gastric mucosa, (b) 10 cases of stomach with intestinal metaplasia with and without inflammation, (c) 10 cases of mucosa with low-grade dysplasia (d) 10 cases of mucosa with high-grade dysplasia, (e) 10 cases of gastric adenocarcinoma and (f) 20 cases of metastatic gastric carcinoma. A correlation between XPO1 expression, the pathological and clinical features of the disease as well as survival were analyzed. Gastric cancer cell lines were exposed to the Selective Inhibitors of Nuclear Export (SINE) compounds (selinexor, KPT-8602, KPT-185, or the natural agent, leptomycin B (LMB), then analyzed using cytotoxicity and molecular assays. In addition, the activity of selinexor was evaluated in a sub-cutaneous xenograft of gastric cancer cell line NCI-N87. XPO1 served as a prognostic marker for poor outcome as positive staining of XPO1 in GC correlated with aggressive behavior of the disease. Targeting XPO1 using SINE compounds or LMB resulted in inhibition of GC cellular growth (IC50 Citation Format: Irfana Muqbil, Zaid Mahdi, Rahman Choudhary, Erkan Baloglu, William Senapedis, Yosef Landesman, Sharon Shacham, Michael Kauffman, Steve Kim, Rafic Beydoun, Richard N. Berri, Anthony Shields, Ramzi M. Mohammad, Asfar S. Azmi. Nuclear exporter protein XPO1 a novel prognostic and therapeutic target in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2491.

  • XPO1 target occupancy measurements confirm the selinexor recommended phase 2 dose
    Oncotarget, 2017
    Co-Authors: Marsha Crochiere, Erkan Baloglu, Sharon Shacham, Michael Kauffman, Stefan Hannus, Kerrin Hansen, Frank Becker, Margaret S. Lee, Yosef Landesman
    Abstract:

    XPO1 (exportin 1) is the main nuclear export protein with over 200 different protein cargos. XPO1 is overexpressed in tumor cells and high levels are correlated with poor prognosis. Selective Inhibitor of Nuclear Export (SINE) compounds block nuclear export by inhibiting XPO1. The first SINE compound, selinexor, shows promising anti-cancer activity across hematological and solid tumors in Phase 2 and 3 clinical trials. The 2nd generation SINE compound KPT-8602 is being evaluated as an anti-cancer agent in a Phase 1 clinical trial. To predict patient response to treatment and confirm the selinexor recommended phase 2 dose (RP2D), an assay based on fluorescence cross correlation spectroscopy that measures XPO1 occupancy in cancer cells was developed. Studies comparing cytotoxicity and XPO1 occupancy in cell lines treated with selinexor or KPT-8602 indicated that XPO1 occupancy by both compounds could reach saturation regardless of drug sensitivity. However, higher levels of XPO1 protein correlated with lower sensitivity to SINE compound cytotoxicity. In vivo mouse studies showed XPO1 occupancy could be measured in tumors and was dose-dependent, with >90% target saturation at 10 mg/kg (∼50 mg flat dose in humans). Drug-target occupancy was measured in a dose-response time course and full occupancy occurred by 6 hours at all doses. The duration of occupancy was dose-dependent, where 10-15 mg/kg in mice (∼ 50-75 mg human flat dose) was necessary to maintain XPO1 occupancy up to 48 hours post-dose. These findings confirm the selinexor RP2D of 60 mg for achieving target occupancy and inhibition up to 48 hours.

  • Abstract 464: Novel role of XPO1 in regulating MicroRNAs related to pancreatic ductal adenocarcinoma invasion and metastasis
    Molecular and Cellular Biology Genetics, 2017
    Co-Authors: Asfar S. Azmi, Irfana Muqbil, William Senapedis, Erkan Baloglu, Sharon Shacham, Yosef Landesman, Michael Kauffman, Amro Aboukameel, Philip A. Philip
    Abstract:

    Objective: There are no known reports on the role of exportin 1 (XPO1; also known as chromosome maintenance region 1 [CRM1]) in microRNA biology. In this study, we for the first time demonstrate that interfering with XPO1 machinery can influence miRNA signaling leading to suppression of pancreatic ductal adenocarcinoma (PDAC) proliferation, invasion and metastasis. Methods: miRNA arrays (LCSciences, Houston, TX) were performed on total RNA samples from PDAC cell lines (HPAC, MiaPaCa-2, AsPc-1 and L3.6pl) and normal human pancreatic ductal epithelial (HPDE) cells. PDAC cells were treated with XPO1 inhibitor (Selinexor) or transfected with control siRNA, XPO1 siRNA (Santa Cruz), miR-control or miR-145 mimic (Applied biosystems) all at a final concentration of 20 nM using DharmaFact Transfection Reagent (Dharmacon, Lafayette. CO). The total RNA and total protein from treated or transfected cells were subjected to real-time PCR or immunoblot analysis in order to measure expression level of miR-145, let-7d, miR-34c, miR-320, miR-205, and miR-145 target or downstream genes including EGFR, MMP1, MT-MMP, c-Myc, Sox-2, and PAK4. The impact of XPO1 inhibitor Selinexor on PDAC growth, proliferation, invasion and migrations was also evaluated using MTT and scratch assay. Results: In this study, we show that PDAC cells have significantly reduced expression of miR-145 when compared to normal pancreatic duct epithelial cells. Similarly, forced expression of miR-145 in PDAC cells inhibited cell proliferation and migration. Conversely, we demonstrate that RNAi of XPO1 by siRNA knockdown or chemical inhibition of XPO1 by selective inhibitor of nuclear export compound (Selinexor) restores miR-145 expression in PDAC cells ultimately leading to inhibition of cell proliferation and migration. In addition, we show that the inhibition of cell proliferation and migration by Selinexor is mediated through the down-regulation of known miR-145 signals including EGFR, MMP1, MT-MMP, c-Myc, PAK4 and Sox-2. Selinexor also induced the expression of two important tumor suppressive miRNAs, miR-34c and let-7d, leading to the up-regulation of p21WAF1. We also observed the down-regulation of oncomir mir-205. Conclusions: These results are the first to show that targeted inhibition of the nuclear exporter protein XPO1 by RNAi or Selinexor could restore tumor suppressive miRs in PDAC. Citation Format: Asfar S. Azmi, Yiwei Li, Irfana Muqbil, Amro Aboukameel, William Senapedis, Erkan Baloglu, Yosef Landesman, Michael Kauffman, Sharon Shacham, Philip A. Philip, Ramzi M. Mohammad. Novel role of XPO1 in regulating MicroRNAs related to pancreatic ductal adenocarcinoma invasion and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 464. doi:10.1158/1538-7445.AM2017-464

Dilara Mccauley - One of the best experts on this subject based on the ideXlab platform.

  • In Vitro and in Vivo Quantification of Exportin-1 (XPO1) Occupancy By the Oral Selective Inhibitor of Nuclear Export (SINE) Selinexor in Multiple Myeloma, Acute Myeloid Leukemia, and Healthy PBMCs
    Blood, 2014
    Co-Authors: Marsha Crochiere, Sharon Tamir, William Senapedis, Erkan Baloglu, Boris Klebanov, Ori Kalid, Trinayan Kashyap, Diego Del Alamo, Tami Rashal, Dilara Mccauley
    Abstract:

    ![Graphic][1] Introduction: SINE are a family of small molecules that selectively inhibit nuclear export by forming a slowly reversible covalent bond with Cysteine 528 (Cys528) in the cargo binding pocket of Exportin 1 (XPO1/CRM1). SINE binding to XPO1 leads to forced nuclear retention and activation of major tumor suppressor proteins (TSPs) such as p53, FOXO, pRB and IkB, resulting in selective death of cancer cells. Selinexor is an orally bioavailable SINE compound currently in human phase I and II clinical trials for advanced hematological and solid cancers. Oral selinexor demonstrates maximal pharmacokinetic exposure at 1-2 hours in humans with associated increases in pharmacodynamic markers of XPO1 inhibition in 2-4 hours that last for up to 48 hours. The goal of this study was to develop a binding assay that would enable quantification of XPO1 occupancy in PBMCs from patients following oral administration of selinexor. Methods: To measure the binding of SINE to XPO1, biotinylated leptomycin B (LMB) was utilized. Biotinylated LMB binds covalently and irreversibly to Cys528 in the cargo-binding site of free XPO1 with activity confirmed to be similar to that of unmodified LMB in cytotoxicity assays. To measure SINE binding to XPO1 in vitro, cancer cell lines and PBMCs from normal human donors were treated with SINE compounds prior to treatment with biotinylated LMB. Any XPO1 that did not bind SINE instead binds to biotinylated LMB and can be quantified. In in vivo studies, mice were treated with selinexor, followed by collection of PBMCs for treatment with biotinylated LMB. After incubation with biotinylated LMB, cells were harvested, lysed, and protein lysates were subjected to pull-down experiments with streptavidin-conjugated beads followed by immunoanalysis of XPO1. Results: To evaluate selinexor-XPO1 binding kinetics in vitro, MM.1S, AML2, AML3, and HEL cells were treated with 0 - 10 µM of SINE compounds and unbound XPO1 was pulled down from cell lysates treated with biotinylated LMB. Immunoanalysis showed that 50% XPO1 occupancy with selinexor was achieved at 0.07 µM in MM.1S, 0.1 µM in AML2, 0.03 µM in AML3, and 0.12 µM in HEL cells. Selinexor-XPO1 occupancy experiments using human PBMCs isolated from donor whole blood showed 50% XPO1 occupancy at 0.05 µM. In mice, 50% XPO1 occupancy in PMBCs was achieved after 4 hours treatment with 1.2 mg/kg (3.6 mg/m2) selinexor, while 90% XPO1 occupancy was achieved at 8.1 mg/kg (24.3 mg/m2). Mice treated with a single dose of selinexor from 1.5 to 10 mg/kg for 4-96 hours revealed sustained, dose dependent XPO1 occupancy in PBMCs for up to 72 hours. Conclusions: We have developed a sensitive and robust assay to measure selinexor binding to XPO1 that can be used to evaluate drug exposure following treatment with oral selinexor in preclinical and clinical studies. Studies are ongoing to determine whether there is a correlation between XPO1 occupancy (pharmacodynamics measurement) with disease response in patients with solid and hematological malignancies. Disclosures Crochiere: Karyopharm: Employment. Klebanov: Karyopharm Therpeutics: Employment. Baloglu: Karyopharm: Employment. Kalid: Karyopharm Therapeutics: Employment. Kashyap: Karyopharm Therapeutics: Employment. Senapedis: Karyopharm: Employment. del Alamo: Karyopharm: Employment. Rashal: Karyopharm Therapeutics: Employment. Tamir: Karyopharm: Employment. McCauley: Karyopharm Therapeutics: Employment, Equity Ownership. Carlson: Karyopharm Therapeutics: Employment. Savona: Karyopharm: Consultancy, Equity Ownership; Gilead: Consultancy; Incyte: Consultancy; Celgene: Consultancy. Kauffman: Karyopharm Therapeutics, Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Shacham: Karyopharm Therapeutics, Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Landesman: Karyopharm Therapeutics: Employment. [1]: /embed/inline-graphic-2.gif

  • Nucleo-cytoplasmic transport as a therapeutic target of cancer
    Journal of Hematology & Oncology, 2014
    Co-Authors: Giovanni Luca Gravina, William Senapedis, Dilara Mccauley, Erkan Baloglu, Sharon Shacham, Claudio Festuccia
    Abstract:

    Shuttling of specific proteins out of the nucleus is essential for the regulation of the cell cycle and proliferation of both normal and malignant tissues. Dysregulation of this fundamental process may affect many other important cellular processes such as tumor growth, inflammatory response, cell cycle, and apoptosis. It is known that XPO1 (Exportin-1/Chromosome Region Maintenance 1/CRM1) is the main mediator of nuclear export in many cell types. Nuclear proteins exported to the cytoplasm by XPO1 include the drug targets topoisomerase IIα (topo IIα) and BCR-ABL and tumor suppressor proteins such as Rb, APC, p53, p21, and p27. XPO1 can mediate cell proliferation through several pathways: (i) the sub-cellular localization of NES-containing oncogenes and tumor suppressor proteins, (ii) the control of the mitotic apparatus and chromosome segregation, and (iii) the maintenance of nuclear and chromosomal structures. The XPO1 protein is elevated in ovarian carcinoma, glioma, osteosarcoma, pancreatic and cervical cancer. There is a growing body of research indicating that XPO1 may have an important role as a prognostic marker in solid tumors. Because of this, nuclear export inhibition through XPO1 is a potential target for therapeutic intervention in many cancers. The best understood XPO1 inhibitors are the small molecule nuclear export inhibitors (NEIs; Leptomycin B and derivatives, ratjadones, PKF050-638, valtrate, ACA, CBS9106, selinexor/KPT-330, and verdinexor/KPT-335). Selinexor and verdinexor are orally bioavailable, highly potent, small molecules that are classified as Selective Inhibitors of Nuclear Export (SINE). KPT-330 is the only NEI currently in Phase I/II human clinical trials in hematological and solid cancers. Of all the potential targets in nuclear cytoplasmic transport, the nuclear export receptor XPO1 remains the best understood and most advanced therapeutic target for the treatment of cancer.

  • XPO1 (CRM1) Inhibition Represses STAT3 Activation to Drive a Survivin-Dependent Oncogenic Switch in Triple-Negative Breast Cancer
    Molecular cancer therapeutics, 2014
    Co-Authors: Yan Cheng, Dilara Mccauley, Sharon Shacham, Yosef Landesman, Michael Kauffman, Michael P. Holloway, Kevin Nguyen, Rachel A. Altura
    Abstract:

    Inhibition of XPO1 (CRM1)-mediated nuclear export of multiple tumor suppressor proteins has been proposed as a novel cancer therapeutic strategy to turn off oncogenic signals and enhance tumor suppression. Survivin is a multifunctional protein with oncogenic properties when expressed in the cytoplasm that requires the XPO1-RanGTP complex for its nuclear export. We investigated the anti-tumor mechanisms of the drug-like selective inhibitors of nuclear export (SINE) XPO1 antagonists, KPT-185, KPT-251 KPT-276, and KPT-330 in estrogen-receptor positive and triple negative breast cancer (TNBC) cell lines and xenograft models of human breast tumors. KPT compounds significantly inhibited breast cancer cell growth and induced tumor cell death, both in vitro and in vivo. These drugs initially promoted survivin accumulation within tumor cell nuclei. However, their major in vitro effect was to decrease survivin cytoplasmic protein levels, correlating with the onset of apoptosis. XPO1 inhibition repressed Survivin transcription by inhibiting CBP-mediated STAT3 acetylation, and blocking STAT3 binding to the Survivin promoter. Additionally, caspase-3 was activated to cleave survivin, rendering it unavailable to bind XIAP and block the caspase cascade. Collectively, these data demonstrate that XPO1 inhibition by SINE compounds represses STAT3 transactivation to block the selective oncogenic properties of survivin and supports their clinical use in triple negative breast tumors.

  • genome wide studies in multiple myeloma identify XPO1 crm1 as a critical target validated using the selective nuclear export inhibitor kpt 276
    Leukemia, 2013
    Co-Authors: Jessica Schmidt, Esteban Braggio, Klaus Martin Kortuem, Jan B. Egan, Yuan-xiao Zhu, C S Xin, Rodger E. Tiedemann, Stephen Palmer, Victoria M. Garbitt, Dilara Mccauley
    Abstract:

    RNA interference screening identified XPO1 (exportin 1) among the 55 most vulnerable targets in multiple myeloma (MM). XPO1 encodes CRM1, a nuclear export protein. XPO1 expression increases with MM disease progression. Patients with MM have a higher expression of XPO1 compared with normal plasma cells (P<0.04) and to patients with monoclonal gammopathy of undetermined significance/smoldering MM (P<0.0001). The highest XPO1 level was found in human MM cell lines (HMCLs). A selective inhibitor of nuclear export compound KPT-276 specifically and irreversibly inhibits the nuclear export function of XPO1. The viability of 12 HMCLs treated with KTP-276 was significantly reduced. KPT-276 also actively induced apoptosis in primary MM patient samples. In gene expression analyses, two genes of probable relevance were dysregulated by KPT-276: cell division cycle 25 homolog A (CDC25A) and bromodomain-containing protein 4 (BRD4), both of which are associated with c-MYC pathway. Western blotting and reverse transcription-PCR confirm that c-MYC, CDC25A and BRD4 are all downregulated after treatment with KPT-276. KPT-276 reduced monoclonal spikes in the Vk*MYC transgenic MM mouse model, and inhibited tumor growth in a xenograft MM mouse model. A phase I clinical trial of an analog of KPT-276 is ongoing in hematological malignancies including MM.

  • Genome-wide studies in multiple myeloma identify XPO1/CRM1 as a critical target validated using the selective nuclear export inhibitor KPT-276.
    Leukemia, 2013
    Co-Authors: Jessica Schmidt, Esteban Braggio, Klaus Martin Kortuem, Jan B. Egan, Yuan-xiao Zhu, C S Xin, Rodger E. Tiedemann, Stephen Palmer, Victoria M. Garbitt, Dilara Mccauley
    Abstract:

    RNA interference screening identified XPO1 (exportin 1) among the 55 most vulnerable targets in multiple myeloma (MM). XPO1 encodes CRM1, a nuclear export protein. XPO1 expression increases with MM disease progression. Patients with MM have a higher expression of XPO1 compared with normal plasma cells (P