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Ovarian tumor AND Ovarian functional and neoplastic tumors [keywords]
- In vivo multiplexed interrogation of amplified genes identifies GAB2 as an ovarian cancer oncogene. [Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't]
- Proc Natl Acad Sci U S A 2014 Jan 21; 111(3):1102-7.
High-grade serous ovarian cancers are characterized by widespread recurrent copy number alterations. Although some regions of copy number change harbor known oncogenes and tumor suppressor genes, the genes targeted by the majority of amplified or deleted regions in ovarian cancer remain undefined. Here we systematically tested amplified genes for their ability to promote tumor formation using an in vivo multiplexed transformation assay. We identified the GRB2-associated binding protein 2 (GAB2) as a recurrently amplified gene that potently transforms immortalized ovarian and fallopian tube secretory epithelial cells. Cancer cell lines overexpressing GAB2 require GAB2 for survival and show evidence of phosphatidylinositol 3-kinase (PI3K) pathway activation, which was required for GAB2-induced transformation. Cell lines overexpressing GAB2 were as sensitive to PI3K inhibition as cell lines harboring mutant PIK3CA. Together, these observations nominate GAB2 as an ovarian cancer oncogene, identify an alternative mechanism to activate PI3K signaling, and underscore the importance of PI3K signaling in this cancer.
- Cyclin E1 deregulation occurs early in secretory cell transformation to promote formation of fallopian tube-derived high-grade serous ovarian cancers. [Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't]
- Cancer Res 2014 Feb 15; 74(4):1141-52.
The 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 is 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 high-grade serous ovarian carcinoma, we evaluated the functional role of cyclin E1 in serous carcinogenesis. Cyclin E1 was expressed in early- and late-stage human tumor samples. In primary human fallopian tube secretory epithelial cells, cyclin E1 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 high-grade serous ovarian carcinomas.
- c-FOS suppresses ovarian cancer progression by changing adhesion. [Journal Article, Research Support, Non-U.S. Gov't]
- Br J Cancer 2014 Feb 4; 110(3):753-63.
C-Fos was initially described as oncogene, but was associated with favourable prognosis in ovarian cancer (OvCa) patients. The molecular and functional aspects underlying this effect are still unknown.Using stable transfectants of SKOV3 and OVCAR8 cells, proliferation, migration, invasion and apoptotic potential of c-FOS-overexpressing clones and controls were compared. Adherence to components of the extracellular matrix was analysed in static assays, and adhesion to E-selectin, endothelial and mesothelial cells in dynamic flow assays. The effect of c-FOS in vivo was studied after intraperitoneal injection of SKOV3 clones into SCID mice, and changes in gene expression were determined by microarray analysis.Tumour growth after injection into SCID mice was strongly delayed by c-FOS overexpression, with reduction of lung metastases and circulating tumour cells. In vitro, c-FOS had only weak influence on proliferation and migration, but was strongly pro-apoptotic. Adhesion to components of the extracellular matrix (collagen I, IV) and to E-selectin, endothelial and mesothelial cells was significantly reduced in c-FOS-overexpressing OvCa cells. This corresponds to deregulation of adhesion proteins and glycosylation enzymes in microarray analysis.In addition to its known pro-apoptotic effect, c-FOS might influence OvCa progression by changing the adhesion of OvCa cells to peritoneal surfaces.
- Fine-scale mapping of the FGFR2 breast cancer risk locus: putative functional variants differentially bind FOXA1 and E2F1. [Journal Article]
- Am J Hum Genet 2013 Dec 5; 93(6):1046-60.
The 10q26 locus in the second intron of FGFR2 is the locus most strongly associated with estrogen-receptor-positive breast cancer in genome-wide association studies. We conducted fine-scale mapping in case-control studies genotyped with a custom chip (iCOGS), comprising 41 studies (n = 89,050) of European ancestry, 9 Asian ancestry studies (n = 13,983), and 2 African ancestry studies (n = 2,028) from the Breast Cancer Association Consortium. We identified three statistically independent risk signals within the locus. Within risk signals 1 and 3, genetic analysis identified five and two variants, respectively, highly correlated with the most strongly associated SNPs. By using a combination of genetic fine mapping, data on DNase hypersensitivity, and electrophoretic mobility shift assays to study protein-DNA binding, we identified rs35054928, rs2981578, and rs45631563 as putative functional SNPs. Chromatin immunoprecipitation showed that FOXA1 preferentially bound to the risk-associated allele (C) of rs2981578 and was able to recruit ERα to this site in an allele-specific manner, whereas E2F1 preferentially bound the risk variant of rs35054928. The risk alleles were preferentially found in open chromatin and bound by Ser5 phosphorylated RNA polymerase II, suggesting that the risk alleles are associated with changes in transcription. Chromatin conformation capture demonstrated that the risk region was able to interact with the promoter of FGFR2, the likely target gene of this risk region. A role for FOXA1 in mediating breast cancer susceptibility at this locus is consistent with the finding that the FGFR2 risk locus primarily predisposes to estrogen-receptor-positive disease.
- MiR-145 is downregulated in human ovarian cancer and modulates cell growth and invasion by targeting p70S6K1 and MUC1. [Journal Article, Research Support, Non-U.S. Gov't]
- Biochem Biophys Res Commun 2013 Nov 29; 441(4):693-700.
MicroRNAs (miRNAs) are a family of small non-coding RNA molecules that regulate gene expression at post-transcriptional levels. Previous studies have shown that miR-145 is downregulated in human ovarian cancer; however, the roles of miR-145 in ovarian cancer growth and invasion have not been fully demonstrated. In the present study, Northern blot and qRT-PCR analysis indicate that miR-145 is downregulated in ovarian cancer tissues and cell lines, as well as in serum samples of ovarian cancer, compared to healthy ovarian tissues, cell lines and serum samples. Functional studies suggest that miR-145 overexpression leads to the inhibition of colony formation, cell proliferation, cell growth viability and invasion, and the induction of cell apoptosis. In accordance with the effect of miR-145 on cell growth, miR-145 suppresses tumor growth in vivo. MiR-145 is found to negatively regulate P70S6K1 and MUC1 protein levels by directly targeting their 3'UTRs. Importantly, the overexpression of p70S6K1 and MUC1 can restore the cell colony formation and invasion abilities that are reduced by miR-145, respectively. MiR-145 expression is increased after 5-aza-CdR treatment, and 5-aza-CdR treatment results in the same phenotype as the effect of miR-145 overexpression. Our study suggests that miR-145 modulates ovarian cancer growth and invasion by suppressing p70S6K1 and MUC1, functioning as a tumor suppressor. Moreover, our data imply that miR-145 has potential as a miRNA-based therapeutic target for ovarian cancer.
- Knockdown of CRM1 inhibits the nuclear export of p27(Kip1) phosphorylated at serine 10 and plays a role in the pathogenesis of epithelial ovarian cancer. [Journal Article, Research Support, Non-U.S. Gov't]
- Cancer Lett 2014 Feb 1; 343(1):6-13.
In a previous study, the nuclear export protein chromosomal region maintenance (CRM1) was correlated with p27(Kip1) in glioma. The aims of the present study were to investigate the expression of CRM1 and pSer10p27 and their functional roles in epithelial ovarian cancer (EOC) tissues. Using immunohistochemical analysis, CRM1 and pSer10p27 expression levels were shown to be associated with histologic stage and grade (P<0.05). High CRM1 and pSer10p27 expression levels were prognostic indicators of overall survival (P<0.05). Knockdown of CRM1 and pSer10p27 expression arrested cell cycle progression and inhibited the proliferation of SKOV3 cells both in vitro and in vivo. These data support the idea that pSer10p27 and CRM1 play cooperative roles in EOC.
- FGF18 as a prognostic and therapeutic biomarker in ovarian cancer. [Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't]
- J Clin Invest 2013 Oct 1; 123(10):4435-48.
High-throughput genomic technologies have identified biomarkers and potential therapeutic targets for ovarian cancer. Comprehensive functional validation studies of the biological and clinical implications of these biomarkers are needed to advance them toward clinical use. Amplification of chromosomal region 5q31-5q35.3 has been used to predict poor prognosis in patients with advanced stage, high-grade serous ovarian cancer. In this study, we further dissected this large amplicon and identified the overexpression of FGF18 as an independent predictive marker for poor clinical outcome in this patient population. Using cell culture and xenograft models, we show that FGF18 signaling promoted tumor progression by modulating the ovarian tumor aggressiveness and microenvironment. FGF18 controlled migration, invasion, and tumorigenicity of ovarian cancer cells through NF-κB activation, which increased the production of oncogenic cytokines and chemokines. This resulted in a tumor microenvironment characterized by enhanced angiogenesis and augmented tumor-associated macrophage infiltration and M2 polarization. Tumors from ovarian cancer patients had increased FGF18 expression levels with microvessel density and M2 macrophage infiltration, confirming our in vitro results. These findings demonstrate that FGF18 is important for a subset of ovarian cancers and may serve as a therapeutic target.
- Expression proteomics predicts loss of RXR-γ during progression of epithelial ovarian cancer. [Journal Article, Research Support, Non-U.S. Gov't]
- PLoS One 2013; 8(8):e70398.
The process of cellular transformation involves cascades of molecular changes that are modulated through altered epigenetic, transcription, post-translational and protein regulatory networks. Thus, identification of transformation-associated protein alterations can provide an insight into major regulatory pathways activated during disease progression. In the present protein expression profiling approach, we identified differential sets of proteins in a two-dimensional gel electrophoresis screen of a serous ovarian adenocarcinoma progression model. Function-based categorization of the proteins exclusively associated with pre-transformed cells identified four cellular processes of which RXR-γ is known to modulate cellular differentiation and apoptosis. We thus probed the functional relevance of RXR-γ expression and signaling in these two pathways during tumor progression. RXR-γ expression was observed to modulate cellular differentiation and apoptosis in steady-state pre-transformed cells. Interestingly, retinoid treatment was found to enhance RXR-γ expression in transformed cells and sensitize them towards apoptosis in vitro, and also reduce growth of xenografts derived from transformed cells. Our findings emphasize that loss of RXR-γ levels appears to provide mechanistic benefits to transformed cells towards the acquisition of resistance to apoptosis hallmark of cancer, while effective retinoid treatment may present a viable approach towards sensitization of tumor cells to apoptosis through induction of RXR-γ expression.
- Cisplatin causes cell death via TAB1 regulation of p53/MDM2/MDMX circuitry. [Journal Article, Research Support, N.I.H., Extramural]
- Genes Dev 2013 Aug 15; 27(16):1739-51.
The interdependence of p53 and MDM2 is critical for proper cell survival and cell death and, when altered, can lead to tumorigenesis. Mitogen-activated protein kinase (MAPK) signaling pathways function in a wide variety of cellular processes, including cell growth, migration, differentiation, and death. Here we discovered that transforming growth factor β-activated kinase 1 (TAK1)-binding protein 1 (TAB1), an activator of TAK1 and of p38α, associates with and inhibits the E3 ligase activity of MDM2 toward p53 and its homolog, MDMX. Depletion of TAB1 inhibits MDM2 siRNA-mediated p53 accumulation and p21 induction, partially rescuing cell cycle arrest induced by MDM2 ablation. Interestingly, of several agents commonly used as DNA-damaging therapeutics, only cell death caused by cisplatin is mitigated by knockdown of TAB1. Two mechanisms are required for TAB1 to regulate apoptosis in cisplatin-treated cells. First, p38α is activated by TAB1 to phosphorylate p53 N-terminal sites, leading to selective induction of p53 targets such as NOXA. Second, MDMX is stabilized in a TAB1-dependent manner and is required for cell death after cisplatin treatment. Interestingly TAB1 levels are relatively low in cisplatin-resistant clones of ovarian cells and in ovarian patient's tumors compared with normal ovarian tissue. Together, our results indicate that TAB1 is a potential tumor suppressor that serves as a functional link between p53-MDM2 circuitry and a key MAPK signaling pathway.
- Integrating multiple types of data to identify microRNA-gene co-modules. [Journal Article, Research Support, Non-U.S. Gov't]
- Methods Mol Biol 2013.:215-29.
MicroRNAs (miRNAs) and genes work cooperatively to form the kernel part of gene regulatory system and affect many crucial biological processes. However, the detailed combinatorial roles of most miRNAs and genes in cellular processes and diseases are still unclear. The huge amount of diverse functional genomic data provides unprecedented opportunities to study the miRNA-gene co-regulations. How to integrate diverse genomic data to identify the regulatory modules of miRNAs and genes is a challenging problem in computational biology. Recently, we have proposed a mathematical data integration framework to discover the miRNA-gene regulatory co-modules. We have applied the proposed method to integrate a set of heterogeneous data sources including the expression profiles of miRNAs and genes on 385 human ovarian cancer samples as well as miRNA-gene interactions and gene-gene interactions. The revealed co-modules show significant biological relevance and potential associations with ovarian cancers and others.