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Chaeyong Jung - One of the best experts on this subject based on the ideXlab platform.

  • HOXB13 mediated suppression of p21waf1 cip1 regulates jnk c jun signaling in prostate cancer cells
    Oncology Reports, 2016
    Co-Authors: Taek Won Kang, Phuong Kim To, Nguyen Thi Xuan Nguyen, Chaeyong Jung
    Abstract:

    : Many prostate cancer (PCa) patients die of recurrent disease due to the emergence of hormone-independent cancer cells of which the mechanism is not fully understood. Our previous studies demonstrated that most castration- resistant prostate cancers (CRPC) overexpress the HOXB13 transcription factor to confer positive growth signals. Since HOXB13 also suppresses p21WAF1/CIP1 (p21) expression, we studied the correlation between HOXB13 and p21 in selected samples of PCa. While there was no statistically significant correlation between expression of HOXB13 and p21, HOXB13-deficient tumors had three times higher odds for expressing p21 than HOXB13-positive tumors. Moreover, CRPC showed more negative correlation than hormone-dependent PCa (HDPC). Further in vitro proliferation assay demonstrated that androgen did not affect the growth-suppressive function of p21 in androgen-dependent PCa cells, suggesting that p21 seems to override the growth-promoting function of androgen and suppression of p21 expression by HOXB13 is an important step in PCa cell survival under no androgen influence. HOXB13 also inhibited AP-1 signals via suppressed expression of JNK/c-Jun. While HOXB13 suppressed p21 expression via regulation of JNK signals, alteration of p21 expression also affected c-Jun and AP-1 activity. Taken together, overexpression of HOXB13 in CRPC is an important step in avoiding the growth-suppressive effect of p21 in a harsh condition such as an androgen-deprived environment.

  • HOXB13-mediated suppression of p21WAF1/CIP1 regulates JNK/c-Jun signaling in prostate cancer cells.
    Oncology Reports, 2016
    Co-Authors: Taek Won Kang, Phuong Kim To, Nguyen Thi Xuan Nguyen, Chaeyong Jung
    Abstract:

    : Many prostate cancer (PCa) patients die of recurrent disease due to the emergence of hormone-independent cancer cells of which the mechanism is not fully understood. Our previous studies demonstrated that most castration- resistant prostate cancers (CRPC) overexpress the HOXB13 transcription factor to confer positive growth signals. Since HOXB13 also suppresses p21WAF1/CIP1 (p21) expression, we studied the correlation between HOXB13 and p21 in selected samples of PCa. While there was no statistically significant correlation between expression of HOXB13 and p21, HOXB13-deficient tumors had three times higher odds for expressing p21 than HOXB13-positive tumors. Moreover, CRPC showed more negative correlation than hormone-dependent PCa (HDPC). Further in vitro proliferation assay demonstrated that androgen did not affect the growth-suppressive function of p21 in androgen-dependent PCa cells, suggesting that p21 seems to override the growth-promoting function of androgen and suppression of p21 expression by HOXB13 is an important step in PCa cell survival under no androgen influence. HOXB13 also inhibited AP-1 signals via suppressed expression of JNK/c-Jun. While HOXB13 suppressed p21 expression via regulation of JNK signals, alteration of p21 expression also affected c-Jun and AP-1 activity. Taken together, overexpression of HOXB13 in CRPC is an important step in avoiding the growth-suppressive effect of p21 in a harsh condition such as an androgen-deprived environment.

  • HOXB13 downregulates intracellular zinc and increases nf κb signaling to promote prostate cancer metastasis
    Oncogene, 2014
    Co-Authors: T W Kang, C Choi, Chaeyong Jung
    Abstract:

    HOXB13 downregulates intracellular zinc and increases NF-κB signaling to promote prostate cancer metastasis

  • HOXB13 regulates the prostate derived ets factor implications for prostate cancer cell invasion
    International Journal of Oncology, 2014
    Co-Authors: Taek Won Kang, Taeoh Jeong, Chaeyong Jung
    Abstract:

    : HOXB13 has been shown to enhance the invasive potential of breast and endometrial tumors. HOXB13 is also abundant in castration-resistant prostate tumors. To determine the invasive potential of HOXB13 in prostate tumors, highly metastatic PC3 prostate cancer cells were manipulated to express HOXB13 and/or the prostate-derived Ets factor (PDEF). The PDEF is believed to reduce the invasive potential of various tumors, including prostate tumors. To further demonstrate the functional correlation between HOXB13 and PDEF, transwell invasion and gelatin zymography assays were performed. In addition, the western blot analysis was used to demonstrate the expression of PDEF target proteins involved in cancer cell migration and invasion, MMP-9 and survivin. According to the results, HOXB13 promoted PC3 cell migration and invasion. The DNA microarray analysis demonstrated that HOXB13 significantly suppressed the expression of the PDEF. Accordingly, the expression of MMP-9 and survivin was regulated by HOXB13. In addition, HOXB13 promoted the invasive potential of PC3 cells while inhibiting the PDEF. The coexpression of HOXB13 and the PDEF led to moderate retardation of the number of invasive cells, indicating that HOXB13 functionally counteracted cell invasion by reducing PDEF expression. The western blot analysis demonstrated that HOXB13 counteracted the PDEF-mediated inhibition of the expression of PDEF target proteins such as MMP-9 and survivin. The results suggest that the HOXB13-mediated promotion of tumor cell invasion is accomplished mainly through the downregulation of PDEF expression.

  • Five-alpha Reductase Inhibitor Influences Expression of Androgen Receptor and HOXB13 in Human Hyperplastic Prostate Tissue
    International Braz J Urol, 2013
    Co-Authors: Chaeyong Jung, Youngwoong Park, Taek Won Kang
    Abstract:

    Objectives Five-alpha reductase inhibitors (5ARIs) are known as chemopreventive agents in prostate cancer with a risk of high-grade disease. This study evaluated the effects of 5ARI on androgen receptor (AR) and proteins involved in prostate cell growth such as HOXB13 expression in human prostate tissue and LNCaP prostate cancer cells. Materials and Methods We retrospectively selected 21 patients who underwent TURP between March 2007 and February 2010 for previously confirmed BPH by prostate biopsy. They were grouped into control (group 1, n = 9) and 5ARI treatment (group 2, n = 12) before TURP. AR and HOXB13 expression in prostate tissue was evaluated by immunohistochemical staining. We tested the effect of 5ARI on the expression of AR, prostate specific antigen (PSA) and HOXB13 in LNCaP cells. Cells were assessed by Western blot analysis, MTT in vitro proliferation assay, and ELISA. Results: Group 2 showed stronger reactivity for AR and HOXB13 than those of the group 1. MTT assay showed death of LNCaP cells at 25uM of 5ARI. At the same time, ELISA assay for PSA showed that 5ARI inhibited secretion of PSA in LNCaP cells. Western blot analysis showed that 5ARI did not greatly alter AR expression but it stimulated the expression of HOXB13. Conclusions These results demonstrated that 5ARI influences AR and HOXB13 expression in both LNCaP cells and human prostate tissue. In order to use 5ARI in chemoprevention of prostate cancer, we still need to clarify the influence of 5ARI in ARs and oncogenic proteins and its regulation pathway.

Edward V Maytin - One of the best experts on this subject based on the ideXlab platform.

  • persistent inflammation and angiogenesis during wound healing in k14 directed HOXB13 transgenic mice
    Journal of Investigative Dermatology, 2010
    Co-Authors: Judith A Mack, Edward V Maytin
    Abstract:

    Chronic, nonhealing wounds and inadequate tissue repair characterized by excessive fibrosis continue to have a considerable negative effect on health and quality of life. Understanding the molecular events required for adequate healing, including the transcriptional control of wound repair, will be important for the development of future therapies. We previously showed that loss of HOXB13 from murine skin results in enhanced cutaneous wound healing, suggesting that HOXB13 has a negative effect on wound repair. To test this, we generated skin-specific HOXB13 transgenic (TG) mice that overexpress HOXB13 in the basal layer of the epidermis by the human keratin 14 promoter. Using these mice, we evaluated the effects of HOXB13 overexpression on cutaneous wound healing. Transgenic wounds were characterized by persistence of the fibrin clot and prolonged inflammation. Notably, neutrophils, which had cleared from wild-type wounds, were still pronounced in TG wounds. Marked epidermal hyperplasia was observed at TG wound edges, and dermal vessels were grossly abnormal compared with wild-type mice. Both vascular endothelial growth factor and tumor necrosis factor-α were upregulated in HOXB13 TG skin. Together, our results identify HOXB13 as a potential important clinical target in wound healing and other pathologies characterized by abnormal or excessive inflammation, angiogenesis, or epidermal proliferation.

  • HOXB13 up regulates transglutaminase activity and drives terminal differentiation in an epidermal organotypic model
    Journal of Biological Chemistry, 2005
    Co-Authors: Judith A Mack, Vincent C Hascall, Ling Li, Nobuyuki Sato, Edward V Maytin
    Abstract:

    Abstract Hox genes act to differentiate and pattern embryonic structures by promoting the proliferation of specific cell types. An exception is HOXB13, which functions as a proapoptotic and antiproliferative protein during development of the caudal spinal cord and tail vertebrae and has also been implicated in adult cutaneous wound repair. The adult epidermis, which expresses several Hox genes including HOXB13, is continually renewed in a program of growth arrest, differentiation, and a specialized form of apoptosis (cornification). Yet little is known about the function(s) of these genes in skin. Based on its role during embryogenesis, HOXB13 is an attractive candidate to be involved in the regulation of epidermal differentiation. Here, we demonstrate that HOXB13 overexpression in an adult organotypic epidermal model recapitulates actions of HOXB13 reported in embryonic development. Epidermal cell proliferation is decreased, apoptosis increased, and excessive terminal differentiation observed, as characterized by enhanced transglutaminase activity and excessive cornified envelope formation. Overexpression of HOXB13 also produces abnormal phenotypes in the epidermal tissue that resemble certain pathological features of dysplastic skin diseases. Our results suggest that HOXB13 functions to promote epidermal differentiation, a critical process for skin regeneration and for the maintenance of normal barrier function.

  • HOXB13 knockout adult skin exhibits high levels of hyaluronan and enhanced wound healing
    The FASEB Journal, 2003
    Co-Authors: Judith A Mack, Susan R Abramson, Jerusha C Coffin, James K Rothrock, Edward V Maytin, Vincent C Hascall, Corey Largman, Eric J Stelnicki
    Abstract:

    SPECIFIC AIMSExpression levels of the transcriptional regulator HOXB13 are significantly reduced in human fetal cutaneous wounds that heal without a scar compared with unwounded controls. In contrast, HOXB13 down-regulation is not noted in human adult cutaneous wounds vs. unwounded controls. We postulated that reducing or eliminating HOXB13 from adult skin could improve healing. To test this hypothesis, we evaluated incisional and excisional cutaneous wound healing in adult HOXB13 knockout (KO) mice.PRINCIPAL FINDINGS1. HOXB13 is expressed in murine skinHOXB13 mRNA is present in the epidermal and dermal layers of the skin and in RNA derived from primary keratinocyte and fibroblast cell cultures. HOXB13 protein is detected in the nucleus and cytoplasm of the epidermis, epithelial cells of the hair follicle, and dermal fibroblasts and is up-regulated at the wound site. These observations indicate a functional role for HOXB13 in the epidermal and dermal layers of the skin.2. HOXB13 KO adult skin exhibits a t...

Judith A Mack - One of the best experts on this subject based on the ideXlab platform.

  • persistent inflammation and angiogenesis during wound healing in k14 directed HOXB13 transgenic mice
    Journal of Investigative Dermatology, 2010
    Co-Authors: Judith A Mack, Edward V Maytin
    Abstract:

    Chronic, nonhealing wounds and inadequate tissue repair characterized by excessive fibrosis continue to have a considerable negative effect on health and quality of life. Understanding the molecular events required for adequate healing, including the transcriptional control of wound repair, will be important for the development of future therapies. We previously showed that loss of HOXB13 from murine skin results in enhanced cutaneous wound healing, suggesting that HOXB13 has a negative effect on wound repair. To test this, we generated skin-specific HOXB13 transgenic (TG) mice that overexpress HOXB13 in the basal layer of the epidermis by the human keratin 14 promoter. Using these mice, we evaluated the effects of HOXB13 overexpression on cutaneous wound healing. Transgenic wounds were characterized by persistence of the fibrin clot and prolonged inflammation. Notably, neutrophils, which had cleared from wild-type wounds, were still pronounced in TG wounds. Marked epidermal hyperplasia was observed at TG wound edges, and dermal vessels were grossly abnormal compared with wild-type mice. Both vascular endothelial growth factor and tumor necrosis factor-α were upregulated in HOXB13 TG skin. Together, our results identify HOXB13 as a potential important clinical target in wound healing and other pathologies characterized by abnormal or excessive inflammation, angiogenesis, or epidermal proliferation.

  • HOXB13 up regulates transglutaminase activity and drives terminal differentiation in an epidermal organotypic model
    Journal of Biological Chemistry, 2005
    Co-Authors: Judith A Mack, Vincent C Hascall, Ling Li, Nobuyuki Sato, Edward V Maytin
    Abstract:

    Abstract Hox genes act to differentiate and pattern embryonic structures by promoting the proliferation of specific cell types. An exception is HOXB13, which functions as a proapoptotic and antiproliferative protein during development of the caudal spinal cord and tail vertebrae and has also been implicated in adult cutaneous wound repair. The adult epidermis, which expresses several Hox genes including HOXB13, is continually renewed in a program of growth arrest, differentiation, and a specialized form of apoptosis (cornification). Yet little is known about the function(s) of these genes in skin. Based on its role during embryogenesis, HOXB13 is an attractive candidate to be involved in the regulation of epidermal differentiation. Here, we demonstrate that HOXB13 overexpression in an adult organotypic epidermal model recapitulates actions of HOXB13 reported in embryonic development. Epidermal cell proliferation is decreased, apoptosis increased, and excessive terminal differentiation observed, as characterized by enhanced transglutaminase activity and excessive cornified envelope formation. Overexpression of HOXB13 also produces abnormal phenotypes in the epidermal tissue that resemble certain pathological features of dysplastic skin diseases. Our results suggest that HOXB13 functions to promote epidermal differentiation, a critical process for skin regeneration and for the maintenance of normal barrier function.

  • HOXB13 knockout adult skin exhibits high levels of hyaluronan and enhanced wound healing
    The FASEB Journal, 2003
    Co-Authors: Judith A Mack, Susan R Abramson, Jerusha C Coffin, James K Rothrock, Edward V Maytin, Vincent C Hascall, Corey Largman, Eric J Stelnicki
    Abstract:

    SPECIFIC AIMSExpression levels of the transcriptional regulator HOXB13 are significantly reduced in human fetal cutaneous wounds that heal without a scar compared with unwounded controls. In contrast, HOXB13 down-regulation is not noted in human adult cutaneous wounds vs. unwounded controls. We postulated that reducing or eliminating HOXB13 from adult skin could improve healing. To test this hypothesis, we evaluated incisional and excisional cutaneous wound healing in adult HOXB13 knockout (KO) mice.PRINCIPAL FINDINGS1. HOXB13 is expressed in murine skinHOXB13 mRNA is present in the epidermal and dermal layers of the skin and in RNA derived from primary keratinocyte and fibroblast cell cultures. HOXB13 protein is detected in the nucleus and cytoplasm of the epidermis, epithelial cells of the hair follicle, and dermal fibroblasts and is up-regulated at the wound site. These observations indicate a functional role for HOXB13 in the epidermal and dermal layers of the skin.2. HOXB13 KO adult skin exhibits a t...

Olle Stal - One of the best experts on this subject based on the ideXlab platform.

  • abstract 3141 analysis of the endocrine treatment predictive protein HOXB13 in premenopausal breast cancer
    Cancer Research, 2011
    Co-Authors: Piihalotta Jerevall, Agneta Jansson, Marten Ferno, Annchristine Kallstrom, Goran Landberg, Olle Stal
    Abstract:

    Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Homeobox B13 (HOXB13), part of the two-gene expression index H:I, has proven its capacity as a predictive factor of tamoxifen benefit in breast cancer. We have previously shown that in addition to mRNA expression, the protein shows predictive value in postmenopausal patients. High levels were associated with decreased tamoxifen (Tam) benefit and may indicate endocrine resistance, whereas Tam-treated patients with low expression had a longer recurrence-free survival. Here, we have analyzed HOXB13 protein expression in premenopausal breast cancer patients. We quantified the levels of HOXB13 with immunohistochemistry in tumor samples from 487 patients sampled in duplicates on tissue micro arrays. Patients were diagnosed with stage II invasive breast cancer and randomized to Tam or no endocrine treatment. HOXB13 protein analysis was successful in 367 patients. Data were correlated with clinicopathological variables. Using Kaplan Meier analysis to investigate Tam benefit in patients with tumors expressing estrogen receptor (ER) α, progesterone receptor, or both, patients with high HOXB13 levels unexpectedly benefited from Tam (hazard ratio for recurrences 0.43, 95% CI 0.28-1.01, p=0.053). Corresponding numbers for a lower expression were 0.69 (95% CI 0.44-1.07, p=0.1). For further analysis, we stratified the patients based on tumor ERβ status, which seemed to be an indicator of the performance of HOXB13 as a treatment predictive factor. Interaction between HOXB13 expression and benefit from Tam in the ERβ- group was close to significant (p=0.06), and corresponding p-value for the ERβ+ patients was 0.11. In conclusion, endocrine treatment prediction for premenopausal breast cancer patients using the protein levels of HOXB13 does not seem to be as straight forward as in postmenopausal patients. Based on our results, ERβ may be an additional determinant in predicting benefit from Tam-treatment using HOXB13 protein expression. ![Figure][1] Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3141. doi:10.1158/1538-7445.AM2011-3141 [1]: pending:yes

  • predictive relevance of HOXB13 protein expression for tamoxifen benefit in breast cancer
    Breast Cancer Research, 2010
    Co-Authors: Piihalotta Jerevall, Agneta Jansson, Tommy Fornander, Lambert Skoog, Bo Nordenskjold, Olle Stal
    Abstract:

    Introduction The HOXB13:IL17BR index has been identified to predict clinical outcome in the setting of adjuvant tamoxifen monotherapy of breast cancer. Further studies have shown that HOXB13 in particular can indicate benefit of prolonged tamoxifen treatment. Patients with high-expressing tumors did not benefit from prolonged treatment, suggesting that HOXB13 might be involved in tamoxifen resistance. No studies have been made regarding the HOXB13 protein levels in breast cancer. The aim of our study was to investigate whether tamoxifen benefit can be correlated to different levels of HOXB13 protein expression.

  • HOXB13 protein expression predicts the benefit of tamoxifen treatment in breast cancer patients.
    Cancer Research, 2009
    Co-Authors: Piihalotta Jerevall, Agneta Jansson, Tommy Fornander, Lambert Skoog, Bo Nordenskjold, Olle Stal
    Abstract:

    Abstract #6038 Background: The two-gene expression ratio HOXB13:IL17BR , originally from a microarray analysis, has been shown to be indicative of clinical outcome in the setting of adjuvant tamoxifen monotherapy of breast cancer, with a high ratio associated with decreased disease-free survival. Analysis of a cohort of breast cancer patients randomized to 2 or 5 years of adjuvant tamoxifen therapy showed that the two-gene ratio and expression of the HOXB13 gene alone were predictive of the benefit of prolonged tamoxifen treatment. Patients with tumors expressing HOXB13 at high levels were unresponsive to prolonged adjuvant treatment, suggesting that this gene is involved in tamoxifen resistance. It is suggested that a high two-gene ratio may indicate impaired ER signaling, which is known to predict resistance to tamoxifen. To our knowledge, there are no studies investigating the HOXB13 protein levels in breast cancer.
 Methods: We have analyzed the protein expression of HOXB13 with immunohistochemistry in tumor samples from 912 postmenopausal node negative breast cancer patients randomized to 2 years of tamoxifen or no endocrine treatment. After 2 years, recurrence-free patients were randomized to 3 more years of tamoxifen, or no further therapy. This selection enabled us to investigate the treatment predictive value of HOXB13.
 Results: Data on HOXB13 protein expression were obtained from 866 patients (see table). Tamoxifen treated patients with estrogen receptor (ER) positive tumors expressing none or low levels of HOXB13 had a clear benefit from tamoxifen in terms of longer distant recurrence-free survival (hazard ratio (HR) 0.37, 95% CI 0.23-0.60, p=0.000048). However, for patients with a high or intermediate HOXB13 tumor expression, tamoxifen did not prolong the distant recurrence-free survival compared to the untreated patients (HR=0.83, 95% CI 0.45-1.54, p=0.55). The interaction between HOXB13 expression and benefit from tamoxifen was statistically significant (p=0.046). HOXB13 did not have any prognostic value among systemically untreated patients.
 Conclusions: HOXB13 protein level may be used as a predictive marker for tamoxifen treatment, but does not have any prognostic value. Patients with a high expression of HOXB13 do not seem to benefit from tamoxifen. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6038.

  • exploring the two gene ratio in breast cancer independent roles for HOXB13 and il17br in prediction of clinical outcome
    Breast Cancer Research and Treatment, 2008
    Co-Authors: Piihalotta Jerevall, Bo Nordenskjold, Sara Brommesson, Carina Strand, Sofia K Gruvbergersaal, Per Malmstrom, Sten Wingren, Peter Soderkvist, Marten Ferno, Olle Stal
    Abstract:

    BACKGROUND: The two-gene expression ratio HOXB13:IL17BR has been proposed to predict the outcome of tamoxifen-treated breast cancer patients. We intended to examine whether this ratio can predict the benefit of 5 years vs. 2 years of tamoxifen treatment of postmenopausal patients. A further objective was to investigate any prognostic effects of the ratio in systematically untreated premenopausal patients. Based on the current knowledge of HOXB13 and IL17BR, we hypothesized that these genes may have individual prognostic or predictive power. PATIENTS AND METHODS: Expression of HOXB13 and IL17BR were quantified by real-time PCR in tumors from 264 randomized postmenopausal patients and 93 systemically untreated premenopausal patients. RESULTS: A high HOXB13:IL17BR ratio was associated with aggressive tumor characteristics, as were low levels of IL17BR alone. The ratio and HOXB13 alone predicted recurrence-free survival after endocrine treatment, with a benefit of prolonged treatment in estrogen receptor-positive patients correlated to a low ratio (recurrence rate ratio: RR = 0.39; P = 0.030), or low expression of HOXB13 (RR = 0.37; P = 0.015). No difference in recurrence-free survival was seen for the high ratio or high HOXB13 subgroups. The predictive value of HOXB13 and HOXB13:IL17BR was significant in multivariate analysis. In the systemically untreated cohort, only IL17BR showed independent prognostic significance. CONCLUSION: We conclude that the ratio or HOXB13 alone can predict the benefit of endocrine therapy, with a high ratio or a high expression rendering patients less likely to respond. We have also shown that IL17BR might be an independent prognostic factor in breast cancer.

William B Isaacs - One of the best experts on this subject based on the ideXlab platform.

  • updated insights into genetic contribution to prostate cancer predisposition focus on HOXB13
    Canadian Journal of Urology, 2019
    Co-Authors: William B Isaacs, Kathleen A Cooney, Jianfeng Xu
    Abstract:

    : This presentation for the Philadelphia Prostate Cancer Consensus 2019 will focus on recent findings regarding the role of HOXB13 as a prostate cancer susceptibility gene. Factors affecting the frequency of HOXB13 mutations in different prostate cancer populations will be reviewed. A number of these factors are relevant for prostate cancer susceptibility genes in general.

  • HOXB13 interaction with meis1 modifies proliferation and gene expression in prostate cancer
    The Prostate, 2019
    Co-Authors: Dorhyun Johng, Gonzalo Torga, Charles M Ewing, John D Norris, Donald P Mcdonnell, William B Isaacs
    Abstract:

    BACKGROUND: The recurrent p.Gly84Glu germline mutation (G84E) in HOXB13 is consistently associated with prostate cancer (PCa), although the mechanisms underlying such linkage remain elusive. The majority of the PCa-associated HOXB13 mutations identified are localized to two conserved domains in HOXB13 that have been shown to mediate the interaction with MEIS cofactors belonging to the TALE family of homeodomain transcription factors. In this study, we sought to interrogate the biochemical and functional interactions between HOXB13 and MEIS in prostatic cells with a goal of defining how the HOXB13-MEIS complex impacts PCa pathobiology and define the extent to which the oncogenic activity of G84E is related to its effect on HOXB13-MEIS interaction/function. METHODS: HOXB13 and MEIS paralog expression in prostate epithelial cells and PCa cell lines was characterized by qPCR and immunoblot analyses. HOXB13 and MEIS1 co-expression in human prostate tissue was confirmed by IHC, followed by co-IP mapping of HOXB13-MEIS1 interactions. Proliferation of the PCa cell line LAPC4 following shRNA-mediated knockdown of each gene or both genes was assessed using DNA- and metabolic-based assays. Transcriptional targets of HOXB13 and MEIS1 were identified by gene expression profiling and qPCR. Finally, protein stability of HOXB13 in the context of MEIS1 was determined using pulse-chase assays. RESULTS: HOXB13 and MEIS1 are co-expressed and interact in prostate cells. Both of the putative MEIS interacting domains (MID) within HOXB13 were shown to be capable of mediating the interaction between HOXB13 and MEIS1 independently and such interactions were not influenced by the G84E mutation. The inhibitory effect of either HOXB13 or MEIS1 knockdown on cellular proliferation was augmented by knockdown of both genes, and MEIS1 knockdown abolished HOXB13-driven regulation of BCHE and TNFSF10 mRNA expression. Notably, we demonstrated that MEIS1 stabilized the HOXB13 protein in LAPC4 cells. CONCLUSIONS: Our study provides evidence for functional HOXB13-MEIS1 interactions in PCa. MEIS1 may contribute to the cancer-promoting actions of HOXB13 in cellular proliferation and gene regulation by prolonging HOXB13 half-life. Our data demonstrates that G84E is not a loss-of-function mutation that interferes with HOXB13 stability or ability to interact with MEIS1.

  • abstract 2027 global analyses of HOXB13 regulated transcription reveal a potential link between HOXB13 g84e and prostate cancer risk
    Cancer Research, 2016
    Co-Authors: Dorhyun Johng, Charles M Ewing, Michael C Haffner, Steven M Mooney, David Esopi, Shuangling Chen, William B Isaacs
    Abstract:

    Prostate cancer (PCa) is one of the most heritable cancers. However, germline genetic variations that are consistently and highly associated with PCa have remained elusive. Recently, a variety of non-synonymous SNPs in HOXB13 have been identified in prostate cancer patients from distinct ethnic populations. Among the HOXB13 variants, HOXB13 G84E has been consistently shown to associate strongly with increased PCa risk in men of European descent. HOXB13 is a prostate-specific transcription factor that plays a role in prostate development. HOXB13 has also been implicated in various aspects of PCa biology. However, to this date, the exact role of HOXB13 in normal prostate physiology and in PCa biology remains obscure. Our lab previously reported that neither HOXB13 WT nor G84E alone can transform prostate cells and that the G84E variant does not behave differently from HOXB13 WT in interactions with cofactors (AR, MEIS2) and protein half-life. To further delineate the function of HOXB13 in the prostate and to identify G84E-induced alterations that subject G84E carriers to PCa susceptibility, we performed RNA-seq of the LAPC4 prostate cancer cell line overexpressing a control vector, HOXB13 WT or G84E. Comparisons of the RNA-seq datasets were made using Ingenuity Pathway Analysis (IPA) by selecting genes whose expression was altered by 2 standard deviations or higher. Among pathways altered by HOXB13 WT or G84E compared to the vector control dataset, the VDR/RXR activation pathway was negatively regulated by both WT and G84E. When the G84E dataset was compared to the WT dataset, the IPA analysis revealed that G84E can up-regulate the e-NOS signaling pathway. Interestingly, the top contributor to the difference imparted by HOXB13 G84E compared to WT was identified to be a set of genes regulated by HOXB13 itself. Overall, this preliminary analysis suggests that HOXB13 G84E may be a gain-of-function mutation whereby potential tumor-promoting functions of HOXB13 are over-activated. Finally, to further identify targets directly regulated by HOXB13 WT and G84E, we combined the RNA-seq datasets with HOXB13 overexpression ChIP-seq datasets we previously reported and a HOXB13 knockdown dataset in LAPC4 (Norris et al. 2009). We focused initially on genes that were shown to be up- or down-regulated in the same direction in the RNA-seq and HOXB13 knockdown datasets. Those genes were screened for nearby HOXB13 binding sites as annotated in our ChIP-seq analyses, followed by validation with droplet digital PCR. Among the genes that were down-regulated by HOXB13 WT and G84E include INPP4B, TNFSF10, IGFBP3, KLF5 and SOX9, which all have tumor suppressing functions in PCa. Among HOXB13-upregulated genes was BCHE, which is also implicated in the suppression of PCa initiation and progression. These results provide us with potential areas of further investigation in which HOXB13 G84E may differentially regulate transcription of these genes. Citation Format: Dorhyun Johng, Michael C. Haffner, Steven M. Mooney, David M. Esopi, Charles M. Ewing, Shuangling Chen, William B. Isaacs. Global analyses of HOXB13-regulated transcription reveal a potential link between HOXB13 G84E and prostate cancer risk. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2027.

  • the HOXB13 g84e mutation is associated with an increased risk for prostate cancer and other malignancies
    Cancer Epidemiology Biomarkers & Prevention, 2015
    Co-Authors: Jennifer L Beebedimmer, Charles M Ewing, William B Isaacs, Kathleen A Cooney, Matthew A Hathcock, Linda A Okoth, Stephen N Thibodeau
    Abstract:

    Background:A rare non-conservative substitution (G84E) in the HOXB13 gene has been shown to be associated with risk of prostate cancer. DNA samples from male patients included in the Mayo Clinic Biobank (MCB) were genotyped to determine the frequency of the G84E mutation and its association with various cancers. Methods:Subjects were genotyped using a custom TaqMan (Applied Biosystems) assay for G84E (rs138213197). In addition to donating a blood specimen, all MCB participants completed a baseline questionnaire to collect information on medical history and family history of cancer. Results:Forty-nine of 9,012 male patients were carriers of G84E (0.5%). Thirty-one percent (n=2,595) of participants had been diagnosed with cancer, including 51.1% of G84E carriers compared to just 30.6% of non-carriers (p=0.004). G84E was most frequently observed among men with prostate cancer compared to men without cancer (p<0.0001). However, the mutation was also more commonly observed in men with bladder cancer (p=0.06) and leukemia (p=0.01). G84E carriers were more likely to have a positive family history of prostate cancer in a first degree relative compared to non-carriers (36.2% v. 16.0%, p=0.0003). Conclusions: Our study confirms the association between the HOXB13 G84E variant and prostate cancer and suggests a novel association between G84E and leukemia and a suggestive association with bladder cancer. Future investigation is warranted to confirm these associations in order to improve our understanding of the role of germline HOXB13 mutations in human cancer. Impact: The associations between HOXB13 and prostate, leukemia and bladder suggest that this gene is important in carcinogenesis.

  • abstract 2948 HOXB13 investigating mechanisms of g84e mutation associated with prostate carcinogenesis
    Cancer Research, 2014
    Co-Authors: Dorhyun Johng, Charles M Ewing, Steven M Mooney, Shuangling Chen, William B Isaacs
    Abstract:

    Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA In collaboration with Dr. K. Cooney's lab at the Univ of Michigan, our group recently discovered that a recurrent glycine-to-glutamic acid germline mutation (G84E) in HOXB13 is associated with an increased prostate cancer (PCa) risk. HOXB13 is an androgen receptor (AR)-independent prostate-specific transcription factor shown to play a critical role in the development of the mouse prostate. However, the exact function of HOXB13 in normal human prostate biology and the mechanism by which HOXB13 G84E predisposes carriers to PCa remain unknown. The purpose of this study is to test our hypothesis that HOXB13 G84E, by itself or together with other oncogenes, may reprogram normal prostate cells to be prone to transformation, possibly due to altered molecular characteristics that have downstream effects on transcriptional targets. To this end, using patient-derived normal prostate epithelial cells immortalized with hTERT in the presence or absence of transduced AR (957e/hTERT and 957e/hTERT/AR), we generated cell lines stably expressing HOXB13 WT or G84E to examine neoplastic phenotypes and differentiation. In the presence of AR, HOXB13 WT and G84E caused a change in cell morphology to a fibroblast-like appearance and suppressed proliferation without any significant differences between WT and G84E. In the absence of AR, the morphological and growth suppressive effects of HOXB13 were ablated, which indicates a cooperative relationship between HOXB13 and AR. In addition, we analyzed several molecular aspects of HOXB13 WT and G84E such as protein-interactions, subcellular localization and half-life which could hypothetically contribute to carcinogenesis when altered. Whether the HOXB13-MEIS and HOXB13-AR interactions are affected by G84E was studied for the following reasons. Most HOXB13 mutations identified in PCa lie in the MEIS-interacting domains (MID) of HOXB13 and the biological significance of HOX-MEIS complexes has been shown in leukemic transformation. HOXB13 mediates the transcription of a subset of AR-target genes and the HOXB13-AR interaction has been documented. Immunoprecipitation analysis in 957e/hTERT/AR demonstrated that HOXB13 and MEIS2 interact through the MIDs and G84E did not alter this interaction. Additionally, G84E did not disturb the HOXB13-AR interaction. Finally, HOXB13 G84E localized properly to the nucleus and no significant differences were found in the half-lives of HOXB13 WT and G84E, at least in the absence of AR. Taken together, our study suggests that HOXB13 G84E alone or with AR cannot initiate PCa in our cell line model with a caveat that our model does not accurately recapitulate human PCa since patients harbor the G84E mutation throughout development. Moreover, the lack of molecular differences between WT and G84E calls for further investigation of potential areas of G84E-induced alterations, such as gene-protein and protein-protein interactions on a global scale. Citation Format: Dorhyun Johng, Charles M. Ewing, Steven M. Mooney, Shuangling Chen, William B. Isaacs. HOXB13: Investigating mechanisms of G84E mutation associated with prostate carcinogenesis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2948. doi:10.1158/1538-7445.AM2014-2948