The Experts below are selected from a list of 30060 Experts worldwide ranked by ideXlab platform
C. Elizabeth Caldon - One of the best experts on this subject based on the ideXlab platform.
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Cyclin E1 and Cyclin e2 in er breast cancer prospects as biomarkers and therapeutic targets
Endocrine-related Cancer, 2020Co-Authors: C. Elizabeth Caldon, Sarah Alexandrou, Heloisa Milioli, Elgene LimAbstract:Cyclin E1 is one the most promising biomarkers in estrogen receptor positive (ER+) breast cancer for response to the new standard of care drug class, CDK4/6 inhibitors. Because of its strong predictive value, Cyclin E1 expression may be used in the future to triage patients into potential responders and non-responders. Importantly, Cyclin E1 is highly related to Cyclin E2, and both Cyclin E1 and Cyclin E2 are estrogen target genes that can facilitate anti-estrogen resistance and can be highly expressed in breast cancer. However Cyclin E1 and E2 are often expressed in different subsets of patients. This raises questions about whether the expression of Cyclin E1 and Cyclin E2 have different biological drivers, if high expressing subsets represent different clinical subtypes, and how to effectively develop a biomarker for E-Cyclin expression. Finally, several pan-CDK inhibitors that target Cyclin E-CDK2 activity have reached Phase II clinical trials. In this review, we outline the data identifying that different cohorts of patients have high expression of Cyclins E1 and E2 in ER+ cancer and address the implications for biomarker and therapeutic development.
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Cyclin E2 overexpression is associated with endocrine resistance but not insensitivity to CDK2 inhibition in human breast cancer cells
Molecular cancer therapeutics, 2012Co-Authors: C. Elizabeth Caldon, C. Marcelo Sergio, Jian Kang, Anita Muthukaruppan, Marikje N. Boersma, Andrew Stone, Jane Barraclough, Christine Lee, Michael A. Black, Lance D. MillerAbstract:Cyclin E2, but not Cyclin E1, is included in several gene signatures that predict disease progression in either tamoxifen-resistant or metastatic breast cancer. We therefore examined the role of Cyclin E2 in antiestrogen resistance in vitro and its potential for therapeutic targeting through Cyclin-dependent kinase (CDK) inhibition. High expression of CCNE2, but not CCNE1, was characteristic of the luminal B and HER2 subtypes of breast cancer and was strongly predictive of shorter distant metastasis-free survival following endocrine therapy. After antiestrogen treatment of MCF-7 breast cancer cells, Cyclin E2 mRNA and protein were downregulated and Cyclin E2–CDK2 activity decreased. However, this regulation was lost in tamoxifen-resistant (MCF-7 TAMR) cells, which overexpressed Cyclin E2. Expression of either Cyclin E1 or E2 in T-47D breast cancer cells conferred acute antiestrogen resistance, suggesting that Cyclin E overexpression contributes to the antiestrogen resistance of tamoxifen-resistant cells. Ectopic expression of Cyclin E1 or E2 also reduced sensitivity to CDK4, but not CDK2, inhibition. Proliferation of tamoxifen-resistant cells was inhibited by RNAi-mediated knockdown of Cyclin E1, Cyclin E2, or CDK2. Furthermore, CDK2 inhibition of E-Cyclin overexpressing cells and tamoxifen-resistant cells restored sensitivity to tamoxifen or CDK4 inhibition. Cyclin E2 overexpression is therefore a potential mechanism of resistance to both endocrine therapy and CDK4 inhibition. CDK2 inhibitors hold promise as a component of combination therapies in endocrine-resistant disease as they effectively inhibit Cyclin E1 and E2 overexpressing cells and enhance the efficacy of other therapeutics.
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Estrogen Regulation of Cyclin E2 Requires Cyclin D1 but Not c-Myc
Molecular and Cellular Biology, 2009Co-Authors: C. Elizabeth Caldon, C. Marcelo Sergio, Judith Schütte, Marijke N. Boersma, Jason S. Carroll, Robert L. Sutherland, E A MusgroveAbstract:During estrogen-induced proliferation, c-Myc and Cyclin D1 initiate independent pathways that activate Cyclin E1-Cdk2 by sequestration and/or downregulation of the CDK inhibitor p21Waf1/Cip1, without significant increases in Cyclin E1 protein levels. In contrast, Cyclin E2 undergoes a marked increase in expression, which occurs within 9 to 12 h of estrogen treatment of antiestrogen-pretreated MCF-7 breast cancer cells. Both E Cyclins are important to estrogen action, as small interfering RNA (siRNA)-mediated knockdown of either Cyclin E1 or Cyclin E2 attenuated estrogen-mediated proliferation. Inducible expression of Cyclin D1 upregulated Cyclin E2, while siRNA-mediated knockdown of Cyclin D1 attenuated estrogen effects on Cyclin E2. However, manipulation of c-Myc levels did not profoundly affect Cyclin E2. Cyclin E2 induction by estrogen was accompanied by recruitment of E2F1 to the Cyclin E1 and E2 promoters, and Cyclin D1 induction was sufficient for E2F1 recruitment. siRNA-mediated knockdown of the chromatin remodelling factor CHD8 prevented Cyclin E2 upregulation. Together, these data indicate that Cyclin E2-Cdk2 activation by estrogen occurs via E2F- and CHD8-mediated transcription of Cyclin E2 downstream of Cyclin D1. This contrasts with the predominant regulation of Cyclin E1-Cdk2 activity via CDK inhibitor association downstream of both c-Myc and Cyclin D1 and indicates that Cyclins E1 and E2 are not always coordinately regulated.
Haibo Pan - One of the best experts on this subject based on the ideXlab platform.
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synergistic effect of black tea polyphenol theaflavin 3 3 digallate with cisplatin against cisplatin resistant human ovarian cancer cells
Journal of Functional Foods, 2018Co-Authors: Haibo Pan, Gary O Rankin, Yon Rojanasakul, Yi Charlie ChenAbstract:Theaflavin-3, 3'-digallate (TF3) is a phenolic compound extracted from black tea. We previously demonstrated that TF3 selectively inhibited ovarian cancer cells. Ovarian cancer has high death rate because of acquired cisplatin resistance. We aimed to investigate the synergistic effect of TF3 and cisplatin (CDDP) against cisplatin resistant ovarian cancer cells. In the present study, combination treatment with TF3 and CDDP showed a synergistic cytotoxic effect in A2780/CP70 and OVCAR3 cells. Combination treatment showed a synergistic pro-apoptotic effect and synergistically induced G1/S phase cell cycle arrest. Synergistic apoptosis was accompanied by regulating protein expression of cleaved caspase 3/7, cytochrome c, Bax and Bcl-2. Combination treatment induced G1/S phase cell cycle arrest via regulating protein expression of Cyclin A2, Cyclin D1, Cyclin E1 and CDK2/4. Combination treatment could synergistically down-regulate Akt phosphorylation in both cell lines. TF3 may be used as an adjuvant for the treatment of advanced ovarian cancer.
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inhibitory effect of black tea pigments theaflavin 3 3 gallate against cisplatin resistant ovarian cancer cells by inducing apoptosis and g1 cell cycle arrest
International Journal of Oncology, 2017Co-Authors: Haibo Pan, Gary O Rankin, Yon Rojanasakul, Fang Wang, Yi Charlie ChenAbstract:Adverse side effects and acquired resistance to conventional chemotherapy based on platinum drive the exploration of other selective anticancer drugs. Theaflavin-3-gallate (TF2a) and theaflavin-3′-gallate (TF2b), theaflavin monomers in black tea, exhibited a potent growth inhibitory effect on cisplatin-resistant ovarian cancer A2780/CP70 cells and were less cytotoxic to normal ovarian IOSE-364 cell line. Flow cytometry analysis and western blotting indicated that TF2a and TF2b induced apoptosis and G1 cell cycle arrest in ovarian cancer A2780/CP70 cells. Hoechst 33342 staining was used to confirm the apoptotic effect. Downregulation of CDK2 and CDK4 for TF2a and CDK2 and Cyclin E1 for TF2b led to the accumulation of cells in G1 phase. TF2a and TF2b induced apoptosis and G1 through p53-dependent pathways. TF2a and TF2b induced DNA damage through ATM/Chk/p53 pathway. TF2a and TF2b also induced inhibition of A2780/CP70 cells through Akt and MAPK pathways. The results of this study implied that TF2a and TF2b might help prevent and treat platinum-resistant ovarian cancer.
Yi Charlie Chen - One of the best experts on this subject based on the ideXlab platform.
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synergistic effect of black tea polyphenol theaflavin 3 3 digallate with cisplatin against cisplatin resistant human ovarian cancer cells
Journal of Functional Foods, 2018Co-Authors: Haibo Pan, Gary O Rankin, Yon Rojanasakul, Yi Charlie ChenAbstract:Theaflavin-3, 3'-digallate (TF3) is a phenolic compound extracted from black tea. We previously demonstrated that TF3 selectively inhibited ovarian cancer cells. Ovarian cancer has high death rate because of acquired cisplatin resistance. We aimed to investigate the synergistic effect of TF3 and cisplatin (CDDP) against cisplatin resistant ovarian cancer cells. In the present study, combination treatment with TF3 and CDDP showed a synergistic cytotoxic effect in A2780/CP70 and OVCAR3 cells. Combination treatment showed a synergistic pro-apoptotic effect and synergistically induced G1/S phase cell cycle arrest. Synergistic apoptosis was accompanied by regulating protein expression of cleaved caspase 3/7, cytochrome c, Bax and Bcl-2. Combination treatment induced G1/S phase cell cycle arrest via regulating protein expression of Cyclin A2, Cyclin D1, Cyclin E1 and CDK2/4. Combination treatment could synergistically down-regulate Akt phosphorylation in both cell lines. TF3 may be used as an adjuvant for the treatment of advanced ovarian cancer.
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inhibitory effect of black tea pigments theaflavin 3 3 gallate against cisplatin resistant ovarian cancer cells by inducing apoptosis and g1 cell cycle arrest
International Journal of Oncology, 2017Co-Authors: Haibo Pan, Gary O Rankin, Yon Rojanasakul, Fang Wang, Yi Charlie ChenAbstract:Adverse side effects and acquired resistance to conventional chemotherapy based on platinum drive the exploration of other selective anticancer drugs. Theaflavin-3-gallate (TF2a) and theaflavin-3′-gallate (TF2b), theaflavin monomers in black tea, exhibited a potent growth inhibitory effect on cisplatin-resistant ovarian cancer A2780/CP70 cells and were less cytotoxic to normal ovarian IOSE-364 cell line. Flow cytometry analysis and western blotting indicated that TF2a and TF2b induced apoptosis and G1 cell cycle arrest in ovarian cancer A2780/CP70 cells. Hoechst 33342 staining was used to confirm the apoptotic effect. Downregulation of CDK2 and CDK4 for TF2a and CDK2 and Cyclin E1 for TF2b led to the accumulation of cells in G1 phase. TF2a and TF2b induced apoptosis and G1 through p53-dependent pathways. TF2a and TF2b induced DNA damage through ATM/Chk/p53 pathway. TF2a and TF2b also induced inhibition of A2780/CP70 cells through Akt and MAPK pathways. The results of this study implied that TF2a and TF2b might help prevent and treat platinum-resistant ovarian cancer.
Yan Geng - One of the best experts on this subject based on the ideXlab platform.
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the requirement for Cyclin e in c myc overexpressing breast cancers
Cell Cycle, 2020Co-Authors: Yan Geng, Yu Zhou, Yujiao Zhang, Yubin Zhou, Chen Chu, Samanta Sharma, Anne Fassl, Deborah ButterAbstract:Basal-like triple-negative breast cancers frequently express high levels of c-Myc. This oncoprotein signals to the core cell cycle machinery by impinging on Cyclin E. High levels of E-type Cyclins (E1 and E2) are often seen in human triple-negative breast tumors. In the current study, we examined the requirement for E-type Cyclins in the c-Myc-driven mouse model of breast cancer (MMTV-c-Myc mice). To do so, we crossed Cyclin E1- (E1-/-) and E2- (E2-/-) deficient mice with MMTV-c-Myc animals, and observed the resulting Cyclin E1-/-/MMTV-c-Myc and Cyclin E2-/-/MMTV-c-Myc females for breast cancer incidence. We found that mice lacking Cyclins E1 or E2 developed breast cancers like their Cyclin Ewild-type counterparts. In contrast, further reduction of the dosage of E-Cyclins in Cyclin E1-/-E2+/-/MMTV-c-Myc and Cyclin E1+/-E2-/-/MMTV-c-Myc animals significantly decreased the incidence of mammary carcinomas, revealing arole for E-Cyclins in tumor initiation. We also observed that depletion of E-Cyclins in human triple-negative breast cancer cell lines halted cell cycle progression, indicating that E-Cyclins are essential for tumor cell proliferation. In contrast, we found that the catalytic partner of E-Cyclins, the Cyclin-dependent kinase 2 (CDK2), is dispensable for the proliferation of these cells. These results indicate that E-Cyclins, but not CDK2, play essential and rate-limiting roles in driving the proliferation of c-Myc overexpressing breast cancer cells.
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kinase independent function of e type Cyclins in liver cancer
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: Yan Geng, Wojciech Michowski, Joel M Chick, Yaoyu E Wang, Emmanuelle M Jecrois, Katharine E Sweeney, Lijun Liu, Richard C Han, Agnieszka Zagozdzon, Ewa SicinskaAbstract:E-type Cyclins (Cyclins E1 and E2) are components of the core cell cycle machinery and are overexpressed in many human tumor types. E Cyclins are thought to drive tumor cell proliferation by activating the Cyclin-dependent kinase 2 (CDK2). The Cyclin E1 gene represents the site of recurrent integration of the hepatitis B virus in the pathogenesis of hepatocellular carcinoma, and this event is associated with strong up-regulation of Cyclin E1 expression. Regardless of the underlying mechanism of tumorigenesis, the majority of liver cancers overexpress E-type Cyclins. Here we used conditional Cyclin E knockout mice and a liver cancer model to test the requirement for the function of E Cyclins in liver tumorigenesis. We show that a ubiquitous, global shutdown of E Cyclins did not visibly affect postnatal development or physiology of adult mice. However, an acute ablation of E Cyclins halted liver cancer progression. We demonstrated that also human liver cancer cells critically depend on E Cyclins for proliferation. In contrast, we found that the function of the Cyclin E catalytic partner, CDK2, is dispensable in liver cancer cells. We observed that E Cyclins drive proliferation of tumor cells in a CDK2- and kinase-independent mechanism. Our study suggests that compounds which degrade or inhibit Cyclin E might represent a highly selective therapeutic strategy for patients with liver cancer, as these compounds would selectively cripple proliferation of tumor cells, while sparing normal tissues.
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Generation of tagged Cyclin E1 knock-In mice and analyses of Cyclin E1-containing protein complexes.
2016Co-Authors: Junko Odajima, Yan Geng, Wojciech Michowski, Yaoyu E Wang, Siddharth Saini, Piotr Jung, Yasmine Ndassa-colday, Scott Ficaro, Eugenio Marco, James A. DecaprioAbstract:(A and B) Targeting strategy to knock-in Flag and HA tags into the Cyclin E1 locus to generate N-terminally tagged Cyclin E1Ntag (A) and C-terminally tagged Cyclin E1Ctag alleles (B). The exons are shown as green boxes, Flag tag as a blue box, and HA tag as a red box. Start and stop codons are marked with orange and yellow arrowheads, respectively. The hygromycin resistance cassette (Hyg) with flanking loxP sequences (filled arrows) is also indicated. Restriction enzyme recognition sites: E, EcoRI; A, AflII; Sc, ScaI; N, NotI; X, XhoI; K, KpnI; S, SpeI; P, PmeI; Hp, HpaI. Note that panel (A) was shown in ref [8]. (C) Western blot analysis of wild-type control (Ctrl), heterozygous Cyclin E1+/Ntag, Cyclin E1+/Ctag, and Cyclin E1Ntag/Ctag embryonic stem cells probed with anti-Cyclin E1 and -HA antibodies. Actin served as a loading control. Forth panel: Cyclin E1 was immunoprecipitated with anti-Flag antibody and the immunoblots were probed with anti-Cdk2 antibody. Fifth panel: anti-Flag immunoprecipitates were used for in vitro kinase reactions using histone H1 as a substrate. (D) Same analyses as in (C) using spleens of homozygous knock-in mice. Lanes 1–2 in panels (C and D) were previously shown in [8]. (E) Cyclin E levels detected by western blotting in the indicated organs of 1-month-old mice and in embryonic brain (day E14.5). Actin served as a loading control. The last two lanes (Brain) were previously shown in [8]. (F) Quantification of Cyclin E levels in different organs, normalized against actin (from E). (G) Protein lysates from brains and testes of adult tagged Cyclin E1 knock-in mice were separated by gel-filtration chromatography. Fractions containing protein complexes of the indicated molecular weights were analyzed by western blotting for Cyclin E using an anti-HA antibody. (H) Cyclin E1-associated proteins were purified from the indicated organs of tagged Cyclin E1 knock-in (KI) mice, or from control mice (Ctrl, ‘mock’ purifications) by sequential immunoaffinity purifications with anti-Flag and -HA antibodies, and 10% of the final eluate was resolved on PAGE gels and silver-stained. Arrows indicate bands corresponding to Cyclin E1. Panels representing embryonic and adult brains were previously shown in [8].
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mammalian e type Cyclins control chromosome pairing telomere stability and cdk2 localization in male meiosis
PLOS Genetics, 2014Co-Authors: Laetitia Martinerie, Piotr Sicinski, Yan Geng, Marcia Manterola, Sanny S W Chung, Sunil K Panigrahi, Melissa M Weisbach, Ana Vasileva, Debra J. WolgemuthAbstract:Loss of function of Cyclin E1 or E2, important regulators of the mitotic cell cycle, yields viable mice, but E2-deficient males display reduced fertility. To elucidate the role of E-type Cyclins during spermatogenesis, we characterized their expression patterns and produced additional deletions of CcnE1 and Ccne2 alleles in the germline, revealing unexpected meiotic functions. While Ccne2 mRNA and protein are abundantly expressed in spermatocytes, CcnE1 mRNA is present but its protein is detected only at low levels. However, abundant levels of Cyclin E1 protein are detected in spermatocytes deficient in Cyclin E2 protein. Additional depletion of E-type Cyclins in the germline resulted in increasingly enhanced spermatogenic abnormalities and corresponding decreased fertility and loss of germ cells by apoptosis. Profound meiotic defects were observed in spermatocytes, including abnormal pairing and synapsis of homologous chromosomes, heterologous chromosome associations, unrepaired double-strand DNA breaks, disruptions in telomeric structure and defects in Cyclin-dependent-kinase 2 localization. These results highlight a new role for E-type Cyclins as important regulators of male meiosis.
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concurrent deletion of Cyclin E1 and Cyclin dependent kinase 2 in hepatocytes inhibits dna replication and liver regeneration in mice
Hepatology, 2014Co-Authors: Y A Nevzorova, Piotr Sicinski, Yan Geng, U Haas, C Trautwein, Nives Moro, Mariano Barbacid, C LiedtkeAbstract:The liver has a strong regenerative capacity. After injury, quiescent hepatocytes can reenter the mitotic cell cycle to restore tissue homeostasis. This G0/G1-S cell-cycle transition of primed hepatocytes is regulated by complexes of Cyclin-dependent kinase 2 (Cdk2) with E-type Cyclins (CcnE1 or CcnE2). However, single genetic ablation of either E-Cyclin or Cdk2 does not affect overall liver regeneration. Here, we systematically investigated the contribution of CcnE1, CcnE2, and Cdk2 for liver regeneration after partial hepatectomy (PH) by generating corresponding double- and triple-knockout (KO) mouse mutants. We demonstrate that conditional deletion of Cdk2 alone in hepatocytes resulted in accelerated induction of CcnE1, but otherwise normal initiation of S phase in vivo and in vitro. Excessive CcnE1 did not contribute to a noncanonical kinase activity, but was located at chromatin together with components of the pre-replication complex (pre-RC), such as the minichromosome maintenance (MCM) helicase. Concomitant ablation of Cdk2 and CcnE1 in hepatocytes caused a defect in pre-RC formation and further led to dramatically impaired S-phase progression by down-regulation of Cyclin A2 and cell death in vitro and substantially reduced hepatocyte proliferation and liver regeneration after PH in vivo. Similarly, combined loss of CcnE1 and CcnE2, but also the Cdk2/CcnE1/CcnE2 triple KO in liver, significantly inhibited S-phase initiation and liver mass reconstitution after PH, whereas concomitant ablation of CcnE2 and Cdk2 had no effect. Conclusion: In the absence of Cdk2, CcnE1 performs crucial kinase-independent functions in hepatocytes, which are capable of driving MCM loading on chromatin, Cyclin A2 expression, and S-phase progression. Thus, combined inactivation of Cdk2 and CcnE1 is the minimal requirement for blocking S-phase machinery in vivo. (Hepatology 2014;59:651–660)
Ronny Drapkin - One of the best experts on this subject based on the ideXlab platform.
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replication stress induced by ccnE1 overexpression creates a dependency on xrcc2 at the replication fork
bioRxiv, 2018Co-Authors: Kai Doberstein, Alison M Karst, Paul T Kroeger, Ronny DrapkinAbstract:Across multiple cancer types, genome instability has been linked to aberrant over-expression of CCNE1 due to premature cell cycle entry and replication stress. Using a gain-of-function screen, we found that XRCC2 cooperates with CCNE1 in the neoplastic transformation of TP53 mutant cells. A pan-cancer analysis of TCGA data revealed a striking correlation between CCNE1 and XRCC2 expression and knockdown of XRCC2 in Cyclin E1 overexpressing cell lines is synthetic lethal. Immunopurification of XRCC2 showed that it interacts with the Minichromosome Maintenance Complex Component 7 (MCM7) protein. This interaction appears to be critical for protecting replication forks as knockdown of XRCC2 leads to a strong increase in MCM7 ubiquitination with concomitant decrease in MCM7 protein levels, and reduced replication fork speed. Importantly, Overexpression of MCM7 rescues the effect of XRCC2 knockdown. Our data describe a new dependency of Cyclin E1 overexpressing tumors on factors that stabilize the replication fork.
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Cyclin E1 deregulation occurs early in secretory cell transformation to promote formation of fallopian tube derived high grade serous ovarian cancers
Cancer Research, 2014Co-Authors: Alison M Karst, Paul M Jones, Natalie Vena, Azra H Ligon, Joyce F Liu, Michelle S Hirsch, Dariush Etemadmoghadam, David D L Bowtell, Ronny DrapkinAbstract:Fallopian tube is now generally considered the dominant site of origin for high-grade serous ovarian carcinoma. However, the molecular pathogenesis of fallopian tube-derived serous carcinomas are poorly understood and there are few experimental studies examining the transformation of human fallopian tube cells. Prompted by recent genomic analyses that identified Cyclin E1 (CCNE1) gene amplification as a candidate oncogenic driver in serous ovarian carcinoma, we evaluated the functional role of CCNE1 in serous carcinogenesis. CCNE1 was expressed in early and late stage human tumor samples. In primary human fallopian tube secretory epithelial cells, CCNE1 expression imparted malignant characteristics to untransformed cells if p53 was compromised, promoting an accumulation of DNA damage and altered transcription of DNA damage response genes related to DNA replication stress. Together our findings corroborate the hypothesis that Cyclin E1 dysregulation acts to drive malignant transformation in fallopian tube secretory cells that are the site of origin of serous ovarian carcinomas.
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abstract pr02 Cyclin E1 deregulation occurs early during fallopian tube tumorigenesis and promotes secretory cell transformation
Clinical Cancer Research, 2013Co-Authors: Alison M Karst, Paul M Jones, Natalie Vena, Azra H Ligon, Joyce F Liu, Michelle S Hirsch, Dariush Etemadmoghadam, David D L Bowtell, Ronny DrapkinAbstract:The fallopian tube has been implicated as the dominant site of origin for high-grade serous ovarian carcinoma. However, the molecular pathogenesis of fallopian tube-derived serous cancer is poorly understood and there are few experimental studies examining the transformation of human fallopian tube cells. Recent genomic analyses have identified CCNE1 (Cyclin E1) gene amplification as a potential oncogenic driver of high-grade serous ovarian carcinoma development. Here, we examine the oncogenic role of Cyclin E1 in serous carcinogenesis, first by characterizing its expression in both late-stage and early-stage human tumor samples, and secondly, by generating an experimental model of Cyclin E1-mediated transformation using primary human fallopian tube secretory epithelial cells. Using fluorescent in situ hybridization and immunohistochemical analyses, we show that Cyclin E1 is strongly expressed in a subset of late-stage high-grade serous carcinomas harboring CCNE1 amplification and that aberrant Cyclin E1 expression can occur very early during serous tumorigenesis, evident in non-invasive tubal carcinoma and putative precursor lesions. To examine the effects of constitutive Cyclin E1 expression in untransformed cells, we immortalized human fallopian tube secretory epithelial cells with TERT (telomerase reverse transcriptase) and mutant TP53 R175H (representing early genetic alterations in serous tumorigenesis), followed by overexpression of CCNE1 or a vector control. Using a series of in vitro assays, we show that inappropriate Cyclin E1 expression imparts malignant characteristics to immortal fallopian tube secretory epithelial cells, including accelerated proliferation, loss of contact inhibition, and clonal growth ability. In addition, we use a combination of DNA damage assays and PCR array profiling to demonstrate that Cyclin E1 induces DNA double-strand and single-strand breaks, accompanied by up-regulation of DNA damage response genes involved in managing DNA replication stress. In sum, our results suggest that constitutive Cyclin E1 expression drives over-proliferation of untransformed but p53-compromised fallopian tube secretory epithelial cells, accompanied by an accumulation of DNA damage and altered expression of DNA damage response genes. Our data supports the hypothesis that Cyclin E1 promotes fallopian tube transformation by inducing replication stress-associated DNA damage, thus leading to chromosomal instability, and that CCNE1 amplification is a major driver of Cyclin E1 overexpression in high-grade serous carcinoma. This abstract is also presented as Poster A1. Citation Format: Alison M. Karst, Paul M. Jones, Natalie Vena, Azra H. Ligon, Joyce F. Liu, Michelle S. Hirsch, Dariush Etemadmoghadam, David D. Bowtell, Ronny Drapkin. Cyclin E1 deregulation occurs early during fallopian tube tumorigenesis and promotes secretory cell transformation. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr PR02.
