Ovarian Cancer Tumorigenesis Research Articles

Loss of TAB3 expression by shRNA exhibits suppressive bioactivity and increased chemical sensitivity of ovarian cancer cell lines via the NF-κB pathway.

Ovarian cancer is a leading cause of death among gynaecologic malignancies. Despite many years of research, it still remains sparing in reliable diagnostic markers and methods for early detection and screening. Transforming growth factor β-activated protein kinase 1 (TAK1)-binding protein 3 (TAB3) was initially characterized as an adapter protein essential for TAK1 activation in response to IL-1β or TNFα, however, the physiological role of TAB3 in ovarian cancer tumorigenesis is still not fully understood. In this study, we evaluated the effects of TAB3 on ovarian cancer cell lines. Expressions of TAB3 and PCNA (proliferating cell nuclear antigen) were found to be gradually increased in EOC tissues and cell lines, by western blot analysis and qRT-PCR. Distribution of TAB3 was further analysed by immunohistochemistry. In vitro, knockdown of TAB3 expression in HO8910 or SKOV3 ovarian cancer cells significantly inhibited bioactivity of ovarian cancer cells, including proliferation and cell-cycle distribution, and promoted chemical sensitivity to cisplatin and paclitaxel treatment via inhibiting NF-κB pathways. In conclusion, our study strongly suggests a novel function of TAB3 as an oncogene that could be used as a biomarker for ovarian cancer. It provides a new insight into the potential mechanism for therapeutic targeting, in chemotherapy resistance, common in ovarian cancer.

Inhibition of the Wnt Pathway in Ovarian Cancer Tumorigenesis

Inhibition of the Wnt Pathway in Ovarian Cancer Tumorigenesis

The transcription factor SPDEF suppresses prostate tumor metastasis.

Emerging evidence suggests that the SAM pointed domain containing ETS transcription factor (SPDEF) plays a significant role in tumorigenesis in prostate, breast, colon, and ovarian cancer. However, there are no in vivo studies with respect to the role of SPDEF in tumor metastasis. The present study examined the effects of SPDEF on tumor cell metastasis using prostate tumor cells as a model. Utilizing two experimental metastasis models, we demonstrate that SPDEF inhibits cell migration and invasion in vitro and acts a tumor metastasis suppressor in vivo. Using stable expression of SPDEF in PC3-Luc cells and shRNA-mediated knockdown of SPDEF in LNCaP-Luc cells, we demonstrate for the first time that SPDEF diminished the ability of disseminated tumors cells to survive at secondary sites and establish micrometastases. These effects on tumor metastasis were not a result of the effect of SPDEF on cell growth as SPDEF expression had no effect on cell growth in vitro or subcutaneous tumor xenograft-growth in vivo. Transcriptional analysis of several genes associated with tumor metastasis, invasion, and the epithelial-mesenchymal transition demonstrated that SPDEF expression selectively down-regulated MMP9 and MMP13 in prostate cancer cells. Further analysis indicated that forced MMP9 or MMP13 expression rescued the invasive phenotype in SPDEF expressing PC3 cells in vitro, suggesting that the effects of SPDEF on tumor invasion are mediated, in part, through the suppression of MMP9 and MMP13 expression. These results demonstrate for the first time, in any system, that SPDEF functions as a tumor metastasis suppressor in vivo.

Abstract 763: Exosomal miR-6126 as a novel tumor suppressor in ovarian cancer

Abstract Tumor microenvironment has been known to play a key role in cancer by the development of drug resistance, epithelial-mesenchymal transition, metastasis and angiogenesis. There is emerging evidence that cancer originated exosomes may contribute to the tumor microenvironment to promote tumorigenesis. Exosomes are nano-sized vesicles that contain non-coding RNAs such as miRNAs or siRNAs. Non-coding RNAs are involved in the pathogenesis of the majority of cancer and reveals a new layer of complexity in the molecular architecture of tumorigenicity. The purpose of this study is to identify miRNA content of both sensitive and resistant ovarian cancer-cell derived exosomes for the identification of exosomal RNA-mediated tumorigenesis in ovarian cancer. Using miRNA microarray profiling, we identified differentially expressed exosomal miRNAs in three sensitive (Heya8, Skov3, A2780) and resistant (Heya8-MDR, Skov3-TR, A2780-CP20) isogenic ovarian cancer cell lines. miR-6126 was found to be only miRNA significantly up-regulated in all cancer cell exosomes released to tumor microenvironment. In vitro functional assays showed that miR-6126 act as a tumor suppressor by inhibiting proliferation, migration, invasion and tube formation. miR-6126 acts as a novel potential tumor suppressor through targeting integrin beta-1, leading to inhibition of PI3K/AKT and Ras/Raf signaling. In vivo experiments also demonstrated that administration of miR-6126 into the nude mice with established tumors inhibited tumor weight. Immunohistochemistry results showed that miR-6126 treatment inhibits many oncogenic functions such as proliferation and angiogenesis of ovarian cancer. We believe that these findings help the identification of exosomal RNA-mediated tumorigenesis in ovarian cancer. Citation Format: Pinar Kanlikilicer, Mohammed Mohammed H. S. Rashed, Recep Bayraktar, Rahul Mitra, Cristina Ivan, Burcu Aslan, Xinna Zhang, Rodriguez-Aguayo Cristian, Emine Bayraktar, Martin Picher, Bulent Ozpolat, George A. Calin, Anil K. Sood, Gabriel Lopez-Berestein. Exosomal miR-6126 as a novel tumor suppressor in ovarian cancer. [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 763.

Overexpression of TAZ promotes cell proliferation, migration and epithelial-mesenchymal transition in ovarian cancer.

The Hippo pathway is dysregulated in multiple types of human cancer, including ovarian cancer. Nuclear expression of yes-associated protein 1 (YAP1), a downstream transcription coactivator of the Hippo pathway, has been demonstrated to promote tumorigenesis in ovarian cancer and may serve as a poor prognostic indicator. However, transcriptional coactivator with PDZ binding motif (TAZ), a downstream target of the Hippo pathway and paralog of YAP in mammalian cells, has not been fully investigated in ovarian cancer. The present study aimed to investigate the dysregulation and biological function of TAZ in ovarian cancer. Reverse transcription-quantitative polymerase chain reaction and western blotting revealed that TAZ mRNA and protein levels, respectively, were upregulated in ovarian cancer, and a meta-analysis of ovarian cancer microarray datasets identified that increased expression of TAZ mRNA is correlated with poor prognosis in patients with ovarian cancer. In addition, TAZ-knockdown in ovarian cancer cells demonstrated that TAZ regulates the migration, proliferation and epithelial-mesenchymal transition of ovarian cancer cells. Furthermore, pharmacological disruption of the YAP/TAZ/TEA domain protein complex resulted in a decrease in ovarian cancer cell migration, proliferation and vimentin expression. The results of the present study indicate that the overexpression of TAZ is important in the development and progression of ovarian cancer, and may function as a potential drug target for treatment of this disease entity.

Clinical relevance of circulating cell-free microRNAs in ovarian cancer.

Ovarian cancer is the leading cause of death among gynecologic malignancies. Since ovarian cancer develops asymptomatically, it is often diagnosed at an advanced and incurable stage. Despite many years of research, there is still a lack of reliable diagnostic markers and methods for early detection and screening. Recently, it was discovered that cell-free microRNAs (miRNAs) circulate in the body fluids of healthy and diseased patients, suggesting that they may serve as a novel diagnostic marker. This review summarizes the current knowledge regarding the potential clinical relevance of circulating cell-free miRNA for ovarian cancer diagnosis, prognosis, and therapeutics. Despite the high levels of ribonucleases in many types of body fluids, most of the circulating miRNAs are packaged in microvesicles, exosomes, or apoptotic bodies, are binding to RNA-binding protein such as argonaute 2 or lipoprotein complexes, and are thus highly stable. Cell-free miRNA signatures are known to be parallel to those from the originating tumor cells, indicating that circulating miRNA profiles accurately reflect the tumor profiles. Since it is well established that the dysregulation of miRNAs is involved in the tumorigenesis of ovarian cancer, cell-free miRNAs circulating in body fluids such as serum, plasma, whole blood, and urine may reflect not only the existence of ovarian cancer but also tumor histology, stage, and prognoses of the patients. Several groups have successfully demonstrated that serum or plasma miRNAs are able to discriminate patients with ovarian cancer patients from healthy controls, suggesting that the addition of these miRNAs to current testing regimens may improve diagnosis accuracies for ovarian cancer. Furthermore, recent studies have revealed that changes in levels of cell-free circulating miRNAs are associated with the condition of cancer patients. Discrepancies between the results across studies due to the lack of an established endogenous miRNA control to normalize for circulating miRNA levels, as well as differing extraction and quantification methods, are the pitfalls to be resolved before clinical application. There is still a long way, however, before this can be achieved, and further evidence would make it possible to apply circulating cell-free miRNAs not only as biomarkers but also as potential therapeutic targets for ovarian cancer in the future.

Effect of AURKA Gene Expression Knockdown on Angiogenesis and Tumorigenesis of Human Ovarian Cancer Cell Lines.

Ovarian cancer is one of the most common malignant gynecological cancers. Higher expression of AURKA has been found in immortalized human ovarian epithelial cells in previous studies, implying the relationship between AURKA and ovarian cancer pathogenesis. We investigated the effect of AURKA on angiogenesis and tumorigenesis of human ovarian cancer cells. Firstly, the expression of AURKA in HO8910 and SKOV3 ovarian cancer cell lines was knocked down using a vector expressing a short hairpin small interfering RNA (shRNA). Next, the effect of knockdown of AURKA on cell angiogenesis, proliferation, migration, and invasion was determined by microtubule formation assay, proliferation assay, transwell migration, and invasion assays. In addition, the effect of AURKA knockdown on angiogenesis and tumorigenesis was also determined in a chicken chorioallantoic membrane (CAM) model and in nude mice. The results of the microtubule formation assay indicated that knockdown of AURKA significantly inhibited ovarian cancer cell-induced angiogenesis of endothelial cells compared to its control (P < 0.001). Knockdown of AURKA also significantly inhibited cell proliferation, migration, and invasion of HO8910 and SKOV3 cells in vitro. Furthermore, the Matrigel plug assay showed that knockdown of AURKA significantly repressed ovarian cancer cell-induced angiogenesis in nude mice (P < 0.05), and the CAMs model also showed that AURKA knockdown significantly attenuated the angiogenesis (P < 0.001) and tumorigenesis (P < 0.001) of HO8910 cells compared to the control. Finally, the tumorigenicity assay in vivo further indicated that AURKA shRNA reduced tumorigenesis in nude mice inoculated with ovarian cancer cells (P < 0.001). These results suggest the potential role of AURKA in angiogenesis and tumorigenesis of ovarian cancer, which may provide a potential therapeutic target for the disease.

HuR-regulated lncRNA NEAT1 stability in tumorigenesis and progression of ovarian cancer.

Long noncoding RNAs (lncRNAs) have recently emerged as pivotal regulators in governing fundamental biological processes, as well as in tumorigenesis. The nuclear paraspeckle assembly transcript 1 (NEAT1) is one of the most highly regulated lncRNAs in recent genomic datasets, however, its biological role and regulatory mechanism in ovarian cancer (OC) development and progression are poorly defined. In this study, we identified that NEAT1 was up‐regulated in OC patients and cell lines, and its expression was associated with the FIGO stage and lymph node metastasis. Furthermore, the ectopic expression of NEAT1_1 in OVCAR‐3 cell lines promoted cell proliferation and invasion, whereas knockdown of NEAT1_1 did the opposite. Furthermore, NEAT1_1 was stabilized by an RNA‐binding protein HuR, but suppressed by miR‐124‐3p in OC cells. Accordingly, the increased HuR mRNA and decreased miR‐124‐3p levels were observed in OC patients. These results suggested that lncRNA NEAT1, whose expression was collaboratively controlled by HuR and miR‐124‐3p, could regulate ovarian carcinogenesis and may serve as a potential target for antineoplastic therapies.

The conglomeration of diagnostic, prognostic and therapeutic potential of serum miR-199a and its association with clinicopathological features in epithelial ovarian cancer.

Epithelial ovarian cancer (EOC) is the most lethal cause of morbidity and mortality worldwide. miRNA deregulation evinces a remarkable role in ovarian cancer tumorigenesis. miRNA-199a (miR-199a) is known to be involved in cancer development and progression. Although miR-199a has been studied in various cell types, its correlation with clinicopathological features in EOC has not been documented. In this study, we identified the clinicopathological hallmarks which might be perturbed due to the downregulation of serum miR-199a in EOC. Seventy serum samples from histopathologically confirmed EOC patients and 70 controls were collected. Total RNA from serum was isolated by Trizol method, polyadenylated and reverse transcribed into cDNA. Expression level of miR-199a was detected by using miRNA qRT-PCR. Relative expression was determined with matched controls using U6 snRNA as reference. Level of miR-199a expression was compared with distinct clinicopathological features. Expression of miR-199a was found to be significantly downregulated in comparison with matched normal controls. The expression level of miR-199a was found to be significantly associated with tumor stage, lymph node metastasis, and distal metastasis. Receiver operating characteristic (ROC) curve for diagnostic potential yielded significant area under the curve (AUC) with a considerable sensitivity and specificity. ROC curves for prognosis yielded significant AUCs for histological grade, distal metastasis, lymph node status, and survival. Our findings suggest that miR-199a downregulation might be a potential indicator for disease progression promoting the aggressive tumor progression and be identified as a diagnostic marker to predict the prognosis and survival in EOC patients.

MiR-23b targets cyclin G1 and suppresses ovarian cancer tumorigenesis and progression.

BackgroundIt has been proposed that cyclin G1 (CCNG1) participates in p53-dependent G1–S and G2 checkpoints and might function as an oncogenic protein in the initiation and metastasis of ovarian carcinoma. MicroRNA 23b (miR-23b) is a critical regulatory factor in the progression of many cancer cell types that targets the relevant genes.MethodsMiR-23b expression in ovarian tissues was quantified by quantitative reverse transcription–PCR. The ovarian cancer cell lines OVCAR3, HO8910-PM, and SKOV3/DDP were transfected with miR-23b, after we assayed the cell phenotype and expression of the relevant molecules. Dual-luciferase reporter assay and a xenograft mouse model were used to examine the expression of miR-23b and its target gene CCNG1.ResultsMIR23B mRNA expression was significantly lower in epithelial ovarian carcinoma and borderline tumors than in normal ovarian tissues and benign tumors, and miR-23b expression among ages and pathological subtypes was significantly different. CCNG1 mRNA expression was significantly lower in normal ovarian tissues than in benign tumors, borderline tumors, and ovarian carcinomas, and expression among pathological subtypes was significantly different. MiR-23b overexpression inhibited ovarian cancer cell proliferation, invasion, and migration, and induced apoptosis. Dual-luciferase reporter assay showed that miR-23b bound with the 3′ untranslated region of CCNG1. MiR-23b overexpression significantly downregulated CCNG1, urokinase, survivin, Bcl-xL, P70S6K, and matrix metallopeptidase-9 (MMP9) mRNA and protein expression. Furthermore, miR-23b inhibited tumor growth and suppressed CCNG1 expression in vitro.ConclusionsOur findings show that miR-23b may inhibit ovarian cancer tumorigenesis and progression by downregulating CCNG1 and the expression of the relevant genes. MiR-23b is a potentially novel application for regulating ovarian carcinoma progression.

Estrogen receptor-mediated miR-486-5p regulation of OLFM4 expression in ovarian cancer.

Estrogen signaling influences the development and progression of ovarian tumors, but the underlying mechanisms are not well understood. In a previous study we demonstrated that impairment of estrogen receptor alpha (ERα)-mediated olfactomedin 4 (OLFM4) expression promotes the malignant progression of endometrioid adenocarcinoma, and we identified OLFM4 as a potential target of miR-486-5p. In this study we investigated the role of OLFM4 in ovarian serous adenocarcinoma. Ovarian serous adenocarcinoma tissues had reduced OLFM4 expression. Expression of OLFM4 was positively correlated with ERα expression, and estrogen (E2) treatment in ovarian cancer cells induced OLFM4 expression in an ERα-dependent manner. In contrast to ERα, miR-486-5p levels were inversely correlated with OLFM4 expression in ovarian serous adenocarcinoma. Ovarian cancer cells transfected with miR-486-5p mimics showed decreased OLFM4 mRNA expression, and ovarian cancer cells treated with E2 showed reduced cellular miR-486-5p levels. OLFM4 knockdown enhanced proliferation, migration, and invasion by ovarian cancer cells. Low expression of OLFM4 was also associated with high tumor FIGO stage and poor tumor differentiation. These results suggest OLFM4 is downregulated by miR-486-5p, which contributes to ovarian cancer tumorigenesis. Conversely, estrogen receptor signaling downregulates miR-486-5p and upregulates OLFM4 expression, slowing the development and progression of ovarian cancer.

Abstract A83: Profiling potent, novel protein tyrosine phosphatase 4A3 small molecule inhibitors for ovarian cancer.

Abstract PTP4A3 (also known as PRL-3) is a unique protein tyrosine phosphatase that is highly expressed in human ovarian cancer patient samples. Genetic knockdown studies implicate PTP4A3 in ovarian cancer tumorigenesis and the maintenance of the malignant phenotype. Interestingly, cBioportal data mining reveals that PTP4A3 is one of the most highly amplified genes in ovarian cancer, implicating PTP4A3 as a novel, and to date, largely underexplored potential molecular therapeutic target. Unfortunately, the lack of potent and selective PTP4A3 inhibitors impedes the validation of PTP4A3 as a drug target for ovarian cancer. To drive target validation studies and complement our ongoing cell-based genetic PTP4A3 knockdown strategies, we have developed novel PTP4A3 small molecule inhibitors to delineate its mechanistic role in ovarian cancer and therapeutic potential as a drug target. We resynthesized the most potent published PTP4A3 inhibitor (thienopyridone or JMS-631-050). Concurrently, we discovered a new, more active thienopyridone analog, JMS-631-053. Additionally, we identified a structurally related inactive analog, JMS-557-038, which could be used as a pharmacologically powerful control. JMS-631-050 and JMS-631-053 inhibited recombinant PTP4A3 in vitro phosphatase activity with IC50 values of 138 and 7 nM, respectively. We then profiled the impact of JMS-631-050, JMS-631-053 and JMS-557-038 on cell adhesion-based survival using a panel of eight ovarian cancer cell lines, which included a representative high serous grade ovarian cancer cell line (i.e., OVCAR4) and several drug sensitive/resistant cell line pairs. In all ovarian cancer cells lines tested, both JMS-631-050 and JMS-631-053 inhibited cell adhesion-mediated survival. However, JMS-631-053 displayed more potent cell-based effects than JMS-631-050 in all cell lines evaluated. A2780 cells were the most sensitive to JMS-631-053 effects (EC50=0.60±0.2 μM). Significantly, OVCAR4 cells were also highly sensitive to JMS-631-053 with an EC50=1.5±0.3 μM. Both JMS-631-050 and JMS-631-053 maintained cell-based activity when evaluated in three dimensional cell culture models. As expected the PTP4A3 inactive analog, JMS-557-038 had no effect on cell-adhesion-mediated survival (EC50s&amp;gt;50 μM) in any of the ovarian cancer cell lines tested. Thus, JMS-631-050 and JMS-631-053 are attractive chemotypes for further evaluation as single agents for ovarian cancer. Moreover, as the drug resistant cell lines A2780CP20 and HeyA8MDR retained sensitivity to JMS-631-050 and JMS-631-053, these chemotypes are under evaluation in combination studies using existing ovarian cancer therapies. Hence, JMS-631-050 and JMS-631-053 will be valuable reagents for further validation of PTP4A3 as an ovarian cancer target as well as potential leads for future drug dis. Citation Format: Elizabeth R. Sharlow, Joseph M. Salamoun, Kelley E. McQueeney, Sophie Lewandowski, Jennifer Bryant, Alex Cheung, Paula Pekic, Charles N. Landen, Jr., Peter Wipf, John S. Lazo. Profiling potent, novel protein tyrosine phosphatase 4A3 small molecule inhibitors for ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr A83.

MiR-29b regulates cell proliferation and invasion in human ovarian clear cell carcinoma by targeting Lysyl oxidase (LOX)

Ovarian cancer is the leading cause of death from gynecologic cancer, reflecting its chemoresistance and frequent late diagnosis, and suggesting that a more effective treatment approach is needed. Lysyl oxidase (LOX) is involved in important biological processes such as gene regulation, cell signaling and cell motility, its deregulation contributing to tumor formation and development. Although it is known that LOX is involved in proliferation, migration and invasion in several types of tumors, studies of LOX in ovarian cancers are scarce. To explore the molecular regulation mechanisms in ovarian cancer tumorigenesis, the expression change and the function of LOX was confirmed in ovarian tissues and cells, which suggested that LOX is a tumor suppressor gene. To further understand how LOX expression is regulated in ovarian cancer, microRNAs(miRNAs) were considered because of their role in post-transcriptional regulation of many genes. Recent work has described differential expression of mature miRNAs in human cancers. Bioinformatics prediction which was used to find the appropriate miRNA regulating LOX, revealed that miR-29b regulates LOX protein level via its binding site on the 3'UTR of LOX mRNAin ES-2 cells, a human ovarian clear cell carcinoma cell line. miR-29b knockdown inhibited proliferation and invasion in ES-2 cells. Taken together, these findings suggest that influencing LOX regulation bychanging the level of miR-29b expression could provide a novel potential approachfor treating human ovarian clear cell carcinoma.

The RNA-binding protein LARP1 is a post-transcriptional regulator of survival and tumorigenesis in ovarian cancer.

RNA-binding proteins (RBPs) are increasingly identified as post-transcriptional drivers of cancer progression. The RBP LARP1 is an mRNA stability regulator, and elevated expression of the protein in hepatocellular and lung cancers is correlated with adverse prognosis. LARP1 associates with an mRNA interactome that is enriched for oncogenic transcripts. Here we explore the role of LARP1 in epithelial ovarian cancer, a disease characterized by the rapid acquisition of resistance to chemotherapy through the induction of pro-survival signalling. We show, using ovarian cell lines and xenografts, that LARP1 is required for cancer cell survival and chemotherapy resistance. LARP1 promotes tumour formation in vivo and maintains cancer stem cell-like populations. Using transcriptomic analysis following LARP1 knockdown, cross-referenced against the LARP1 interactome, we identify BCL2 and BIK as LARP1 mRNA targets. We demonstrate that, through an interaction with the 3′ untranslated regions (3′ UTRs) of BCL2 and BIK, LARP1 stabilizes BCL2 but destabilizes BIK with the net effect of resisting apoptosis. Together, our data indicate that by differentially regulating the stability of a selection of mRNAs, LARP1 promotes ovarian cancer progression and chemotherapy resistance.

Overexpression of HE4 (human epididymis protein 4) enhances proliferation, invasion and metastasis of ovarian cancer.

Overexpression of Human epididymis protein 4 (HE4) related with a role in ovarian cancer tumorigenesis while little is known about the molecular mechanism alteration by HE4 up regulation. Here we reported that overexpressed HE4 promoted ovarian cancer cells proliferation, invasion and metastasis. Furthermore, human whole genome gene expression profile microarrays revealed that 231 differentially expressed genes (DEGs) were altered in response to HE4, in which MAPK signaling, ECM receptor, cell cycle, steroid biosynthesis pathways were involved. The findings suggested that overexpressed HE4 played an important role in ovarian cancer progression and metastasis and that HE4 has the potential to serve as a novel therapeutic target for ovarian cancer.

PBOV1 correlates with progression of ovarian cancer and inhibits proliferation of ovarian cancer cells.

Prostate and breast cancer overexpressed 1 (PBOV1) is significantly upregulated in prostate, breast and bladder cancer, while its expression status in ovarian cancer and its clinical significance are unclear. We examined the expression levels of PBOV1 mRNA and protein in ovarian cancer cell lines and primary tissues using real-time PCR and western blotting. Immunohistochemistry was employed to analyze PBOV1 expression in 17 normal ovaries, 13 cystadenoma tissues, 14 borderline tumor tissues, and 165 clinicopathologically characterized ovarian cancers. There was negative PBOV1 expression in the 17 normal ovarian epithelial tissues. Compared to the normal ovarian epithelial cells, PBOV1 mRNA and protein were overexpressed in ovarian cancer cell lines. There was high PBOV1 protein expression in the ovarian cancer tissues from 59 of the 165 (35.8%) patients; PBOV1 expression was weak in 106 (64.2%) patients. Notably, there were significant negative associations between high PBOV1 expression and ascending histological grade, late pT/pN/pM, and International Federation of Gynecology and Obstetrics (FIGO) stage (P<0.05). Patients with high PBOV1 expression had longer overall survival; patients with low PBOV1 expression had shorter survival. Multivariate analysis revealed that PBOV1 upregulation is an independent prognostic indicator for ovarian cancer and might serve as a tumor-suppressor gene. Furthermore, PBOV1 overexpression inhibited ovarian cancer cell proliferation and tumorigenesis in vitro and in a tumor transplantation nude mouse model. In conclusion, our results suggest that PBOV1 may play an important role in suppressing ovarian cancer proliferation and carcinogenesis. PBOV1 may be a novel and useful prognostic marker and potential target for treating human ovarian cancer.

NFATC1 promotes cell growth and tumorigenesis in ovarian cancer up-regulating c-Myc through ERK1/2/p38 MAPK signal pathway

It has been reported that nuclear factor of activated T cells (NFATC1) was up-regulated in cancers mediating malignant behaviors. However, the role of NFATC1 in ovarian cancer has not been elucidated. In the present study, we undertook to explore the clinicopathological significance of NFATC1 expression and the mechanism by which NFATC1 works in ovarian cancer. Expression status of NFATC1 was examined using immunohistochemistry. Both knockdown and re-expression of NFATC1 on ovarian cancer cells were employed to observe the effect overgrowth. It was found that NFATC1 was significantly overexpressed in ovarian cancer tissues in comparison with paired normal control tissues and that overexpression of NFATC1 was significantly associated with metastasis and poor prognosis on clinical tissue level. In in vitro ovarian cancer cell lines, we found that NFATC1 can promote proliferation up-regulating c-myc through activation of ERK1/2/p38/MAPK signal pathway. Together, the results we obtained demonstrated that NFATC1 played oncogenic role in ovarian cancer. Mechanistically, NFATC1 promoted growth of ovarian cancer cells up-regulating c-myc through activation of ERK1/2/p38/MAPK signal pathway, suggesting that NFATC1 might be used as a therapeutic target for ovarian cancer.

RNAi-mediated knockdown of the CLN3 gene inhibits proliferation and promotes apoptosis in drug-resistant ovarian cancer cells.

CLN3 is a recently identified anti-apoptotic gene, which has been demonstrated to be highly expressed in a diverse range of cancer cell lines, including ovarian cancer. In the present study, RNA interference, mediated by a lentivirus expressing CLN3 short hairpin RNA (shRNA) was utilized to knockdown the expression of CLN3 in the A2780 human ovarian cancer cell line, and its cisplatin-resistant and carboplatin-resistant sublines, A2780/DDP and A2780/CBP cells. It was revealed that the mRNA and protein expression levels of CLN3 were significantly reduced in the CLN3-specific shRNA-transduced cells, compared with the untransduced and control shRNA-transduced cells. In addition, specific knockdown of CLN3 in these cells inhibited cell proliferation and led to cell cycle arrest at the G0/G1 phase, with eventual apoptosis. CLN3 knockdown caused increases in the levels of Bax, FAX, cleaved-caspase 3, cleaved-caspase 8 and cleaved-RARP, but decreased the level of Bcl-2. Finally, it was observed that CLN3 depletion markedly reduced the half maximum inhibitory concentration in the A2780/DDP and A2780/CBP cells. Taken together, these data suggested that CLN3 is involved in tumorigenesis and drug resistance in ovarian cancer, and may serve as a promising therapeutic target for its treatment.

Overexpression of SOX2 is involved in paclitaxel resistance of ovarian cancer via the PI3K/Akt pathway.

Paclitaxel is recommended as a first-line chemotherapeutic agent against ovarian cancer, but drug resistance becomes a major limitation of its success clinically. The key molecule or mechanism associated with paclitaxel resistance in ovarian cancer still remains unclear. Sex-determining region Y-box 2 (SOX2) is of vital importance in the regulation of stem cell proliferation and carcinogenesis. The aim of this study was to evaluate the role of SOX2 in ovarian cancer tumorigenesis and paclitaxel resistance. In the present study, the expression of SOX2 was examined by immunohistochemistry (IHC) and real-time PCR in 40 clinical samples and in SKOV3 cells and SKOV3/TAX cells (paclitaxel-resistant human ovarian adenocarcinoma cell line). The effects of SOX2 knockdown on ovarian cancer cell proliferation, migration, and invasion were also studied. The IHC and real-time PCR results showed that the difference of SOX2 expression between ovarian cancer and the adjacent non-tumorous ovarian tissues was statistically significant. Western blot analysis revealed that the PI3K/Akt signaling pathway was inhibited in cells overexpressing SOX2. Western blot analysis showed that the SOX2 protein was overexpressed in paclitaxel-resistant cells and weakly detectable in paclitaxel-sensitive cells. SOX2 silencing significantly potentiated apoptosis induced by paclitaxel in SKOV3-TR with SOX2 knockdown compared to SKOV3-TR transfected with control small interfering RNA (siRNA). Our work indicates SOX2 will become both a rational indicator of ovarian cancer prognosis and a promising target for ovarian cancer gene therapy.

Promoter DNA methylation is associated with KLF11 expression in epithelial ovarian cancer.

As a transforming growth factor-β (TGF-β)-inducible gene, the expression of Krüppel-like transcription factor 11 (KLF11) is altered in several types of cancer. In the current study, through using human 9K CpG island array, KLF11 was identified as one of hypermethylated genes in RAS-transformed ovarian T29H cells. Methylation of the KLF11 promoter was also observed in ovarian cancer tissue samples accompanied by significantly reduced KLF11 gene expression. Interestingly, the expression of SMAD2, SMAD3, and SMAD7 genes was reduced in the tumour, whilst no change was found in TGF-β expression. Our data suggest a relationship between promoter DNA methylation and KLF11 gene expression in ovarian cancer tumorigenesis.