Ovarian Cancer Tumorigenesis Research Articles

PTP1B promotes the malignancy of ovarian cancer cells in a JNK-dependent mechanism

Ovarian cancer is the leading cause of death from gynecological malignancies in women. Diagnosis at the early stage remains challenging and efficient treatment is still highly needed. The development and progression of this cancer is associated with many genetic and epigenetic changes, representing the dysregulation of a highly complex signaling network. Previous studies found that protein-tyrosine phosphatase 1 B (PTP1B) was aberrantly expressed in many types of ovarian cancer cells. The exact role of this protein, however, remains controversial. We found that PTP1B was highly expressed in several ovarian carcinoma cell lines. Changing its expression level strongly affected the malignancy phenotypes of the cultured cancer cells and growth of tumors in nude mice. Further analysis at the molecular level found that overexpression of PTP1B activated the JNK (c-Jun N-terminal kinase) signaling pathway and impacted a set of factors involved in cancer metastasis. Overall, our study suggested that overexpression of PTP1B could be a driving factor in the tumorigenesis and progression of ovarian cancer and restoring the normal expression level of this signaling molecule may represent a promising strategy in treating this disease.

Abstract B22: Capturing L1 retrotransposon-mediated DNA transductions in endometriosis associated ovarian cancers as a way to track tumor development

Abstract Endometrioid ovarian cancer (ENOC) and clear cell ovarian cancer (CCOC) share a common precursor lesion, endometriosis (ectopic growth of uterine lining), hence the designation endometriosis-associated ovarian cancer (EAOC). Women with endometriosis have up to three-fold increased risk of developing ENOC and CCOC. Efforts have been made to look for biomarkers that can help identifying women at risk of developing cancer; however, there are currently no biomarkers that stratify risk of cancer development. We performed whole-genome sequencing (WGS) on 29 ENOC and 35 CCOC cases and observed a frequent transduction event originating from an active LINE-1 (L1) retrotransposable element in the TTC28 gene. Such event occurred in 34% (10/29) of ENOC, and 31% (11/35) of CCOC cases. L1 retrotransposons are repetitive, mobile genetic elements capable of taking downstream DNA fragments and inserting them into random genomic locations via a process called 3’ transduction. Approximately 70-100 different potentially active L1s are epigenetically silenced in normal tissues, but tend to be reactivated in cancers. We subsequently used PCR to validate these TTC28-L1 transductions, and compared their presence to single nucleotide variations (SNVs) and frameshift mutations in formalin-fixed, paraffin-embedded (FFPE) tumor tissues from different tumor sites for 4 ENOC and 3 CCOC cases. We found that these transduction events along with classical driver mutations were almost ubiquitous across the tumor sites, suggesting these L1 events likely occurred early in the malignant transformation of EAOCs. We developed a low-input, probe-based capture assay to test the presence of TTC28-L1 transductions as an alternative method to performing WGS. Oligonucleotide probes tiling 1 kb downstream of active L1s are used to capture DNA fragments containing the transduced DNA, and the fragments are sequenced on the MiSeq next-generation sequencing platform. Analyses are performed using the Geneious software and the published bioinformatics tool Socrates, specific for detecting DNA fragments with split reads (fragments with ends aligning to different parts of the genome). We successfully validated the assay on 9 cases with WGS data: 7 EAOC cases with TTC28-L1 transductions and 2 EAOC cases without TTC28-L1 transductions. DNA extracted from frozen tumor and buffy coat (normal control) were used for each case, and FFPE tissues were used for selected cases. All reads containing the transduction events aligned to genomic coordinates corresponding to the WGS data. While L1-mediated DNA transductions are often passenger events during tumorigenesis, our data suggest that they likely occur early in ovarian cancer tumorigenesis. Our data show that this probe-based capture assay provides an alternative method to WGS, and may be useful in detecting active 3’ transductions in novel cases to track the development of ovarian tumors. Citation Format: Zhouchunyang Xia, Dawn Cochrane, Michael Anglesio, Winnie Yang, Miguel Alcaide, Tayyebeh Nazeran, Janine Senz, Amy Lum, Ali Bashashati, Yikan Wang, Ryan Morin, Sohrab Shah, David Huntsman. Capturing L1 retrotransposon-mediated DNA transductions in endometriosis associated ovarian cancers as a way to track tumor development. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B22.

Prolactin signaling drives tumorigenesis in human high grade serous ovarian cancer cells and in a spontaneous fallopian tube derived model

The pathways responsible for tumorigenesis of high grade serous ovarian cancer (HGSOC) from the fallopian tube epithelium (FTE) are still poorly understood. A human prolactin (PRL) like gene, Prl2c2 was amplified >100 fold in a spontaneous model of FTE-derived ovarian cancer (MOEhigh - murine oviductal epithelium high passage). Prl2c2 stable knockdown in MOEhigh cells demonstrated a significant reduction in cell proliferation, 2-dimensional foci, anchorage independent growth, and blocked tumor formation. The overall survival of ovarian cancer patients from transcriptome analysis of 1868 samples was lower when abundant PRL and prolactin receptors (PRL-R) were expressed. A HGSOC cell line (OVCAR3) and a tumorigenic human FTE cell line (FT33-Tag-Myc) were treated with recombinant PRL and a significant increase in cellular proliferation was detected. A CRISPR/Cas9 mediated PRL-R deletion in OVCAR3 and FT33-Tag-Myc cells demonstrated significant reduction in cell proliferation and eliminated tumor growth using the OVCAR3 model. PRL was found to phosphorylate STAT5, m-TOR and ERK in ovarian cancer cells. This study identified Prl2c2 as a driver of tumorigenesis in a spontaneous model and confirmed that prolactin signaling supports tumorigenesis in high grade serous ovarian cancer.

Abstract 3071: The role of Apela in high-grade serous ovarian cancer

Abstract Objective: To assess the expression of Apela and evaluate its co-expression with cancer stem cell markers and angiogenesis markers in high-grade serous ovarian cancer and further elucidate the role of this poorly characterized gene. Background: High-grade serous ovarian cancer (HGSOC) presents a major therapeutic challenge due to advanced stage at diagnosis, aggressive metastatic behavior, and therapeutic resistance. A critical barrier to progress in early diagnosis and treatment is the lack of understanding of the mechanisms that underlie ovarian cancer tumorigenesis. Apela (Apelin early ligand A), also called Toddler and Elabela, is a novel ligand for the G-coupled protein receptor Apelin-R, which has been implicated in cancer tumorigenesis and angiogenesis through activation of the PIK3-AKT (phosphatidylinositol-4,5-bisphosphate 3-kinase and protein-kinase B) pathway. This signaling pathway plays an important role in embryonic stem cell growth and self-renewal. Current research indicate that Apela may be involved in cancer stem cells and angiogenesis pathways as well. Markers of angioneogenesis (Angptl4 [angiopoietin-like protein 4]) and cancer cell stemness (Nestin and CD133/PROM1), were selected for study with Apela because of known expression in HGSOC and other studies showing co-expression in other high-grade malignancies with Apela. Methods: RNA was extracted from established ovarian cancer cell lines (OVCAR3, OVCAR8, CAOV4, OV90, and SKOV3) and expression of Apela, Apelin (another ligand for the Apelin-R), Apelin-R and ANGPTL-4 was determined by qPCR and normalized to actin expression. Formalin-fixed paraffin-embedded (FFPE) slides of HGSOC tissue and normal adjacent ovarian tissue were subjected to RNAscope Multiplex Fluorescent in situ hybridization (ISH) using individual gene probes for Angptl4, Nestin, CD133 and Apela to detect expression at the mRNA level. Immunohistochemistry (IHC) was then performed to confirm Angptl4, Nestin, CD133 and Apela co-expression at the protein level in the FFPE HCSOC tissue. All images were analyzed by confocal microscopy. The TCGA database was analyzed to determine levels of upregulation of Apela in ovarian cancer. An ovarian cancer microarray using 10 paired matched controls was utilized to further validate the presence of the Results: Apela expression can be detected in FFPE tissue at the RNA level and the same pattern of protein expression is seen with IHC. Apela and Angptl4 co-localize with the cancer stem cell markers nestin and CD133. Apela is upregulated in HGSOC when examining the TCGA database compared to other forms of cancer. Conclusions: Apela is expressed at relatively low levels in established ovarian cancer cell lines. However, Apela is highly localized in ovarian cancer tissue, and is co-expressed with markers of angiogenesis and stem cells, possibly representing a stem cell niche that promotes tumorigenesis. Citation Format: Laura R. Daily, Debolina Ganguly, D Neil Hayes, Yinan Wang, Michelle M. Sims, Jinjun Cheng, Adam C. ElNaggar, Lawrence M. Pfeffer. The role of Apela in high-grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3071.

Overcoming platinum resistance in ovarian cancer by targeting pregnancy-associated plasma protein-a

Objective: Pregnancy-associated plasma protein-A (PAPP-A) promotes insulin-like growth factor (IGF) pathway activity, which directly correlates to ovarian cancer (OC) tumorigenesis. Because inhibition of PAPP-A with a novel monoclonal antibody to PAPP-A (mAb-PA) had preliminary activity in an OC patient-derived xenograft (PDX) model, we hypothesize that adding mAb-PA to carboplatin/paclitaxel (CP) would partially overcome platinum resistance in a panel of OC PDX.

MiR-19a negatively regulated the expression of PTEN and promoted the growth of ovarian cancer cells

Ovarian cancer is the most lethal malignancy of the women genital tract. Exploring novel factors involved in the development of ovarian cancer and characterizing the molecular mechanisms by which regulate the tumorigenesis of ovarian cancer are quite necessary. Here, we found that miR-19a was highly expressed in ovarian cancer tissues and cell lines. Overexpression of miR-19a promoted the viability of ovarian cancer cells, while down-regulation of miR-19a inhibited the growth of ovarian cancer cells. To further understand the underlying molecular mechanism of miR-19a in regulating ovarian cancer cell growth, the downstream targets of miR-19a were predicted. The bioinformatics analysis showed that the tumor suppressor PTEN was found as one of the targeting candidates of miR-19a. MiR-19a bound the 3′-UTR of PTEN and highly expressed miR-19a decreased both the mRNA and protein levels of PTEN in ovarian cancer cells. Overexpression of PTEN suppressed the promoting effect of miR-19a on regulating the growth of ovarian cancer cells. Notably, the expression of miR-19a and PTEN was inversely correlated in ovarian cancer tissues. These results demonstrated the potential oncogenic role of miR-19a in ovarian cancer, which suggested that miR-19a might be a promising target in the diagnosis and treatment of ovarian cancer.

Advances of exosome in the development of ovarian cancer and its diagnostic and therapeutic prospect.

Ovarian cancer is the leading cause of female gynecological cancer mortality. Most patients with ovarian cancer are diagnosed with advanced stage because of lack of early symptoms, physical signs, and sensitive tumor biomarkers. The standard treatment includes cytoreductive surgery and platinum-based chemotherapy (usually platinum combined with paclitaxel). Despite that postoperative adjuvant chemotherapy prolongs survival time, most patients go through relapse within 6–12 months after the treatment. Thus, elucidating the molecular mechanism in cancer development is essential to promote early diagnosis and novel treatments. The role of exosome has been highlighted in multiple research fields in recent years. Exosome has been described as nano-sized vesicle secreted by multiple mammalian cell types, carrying cargos like proteins, miRNAs, mRNAs, and lipids. It participates in the formation of tumor microenvironment and the development of tumorigenesis and drug resistance in ovarian cancer. Meanwhile, it may also play a pivotal role in diagnosis, efficacy evaluation, and prognosis. Besides, studies show that exosome and its processed products have promising value in ovarian cancer treatment. The aim of the current review is to describe the characteristics of exosome in ovarian cancer, especially focusing on its role in immune modulation and drug resistance, hoping to provide new information on its implications in cancer diagnosis and treatment.

Estrogen receptor modulators genistein, daidzein and ERB-041 inhibit cell migration, invasion, proliferation and sphere formation via modulation of FAK and PI3K/AKT signaling in ovarian cancer

BackgroundOvarian cancer is the most lethal gynaecological malignancy. Chemotherapy is the main stay of treatment for metastatic disease, with modest response rates but significant side effects. Therefore, there is a need for alternative therapies that can control the disease while offering good quality of life. Ovarian cancer cells express both estrogen receptor subtypes (ERα and ERβ). There is growing evidence that ERβ is anti-oncogenic. Genistein and daidzein are phytoestrogens found in soybeans and they display higher affinity to bind ERβ. ERB-041 is a potent selective ERβ agonist. In this study, we aimed to investigate the effects of genistein, daidzein and ERB-041 on ovarian cancer.MethodsOvarian cancer cell lines were treated with genistein, daidzein and ERB-041 in pharmacological doses. Cell migration, invasion, proliferation, cell cycle arrest, apoptosis and sphere formation were assessed by Transwell migration and invasion assays, XTT assay, focus formation, flow cytometry and sphere formation assay, respectively. Immunoblotting analysis was performed to determine the downstream signaling pathways.ResultsWe found that genistein, daidzein and ERB-041 significantly inhibited ovarian cancer cell migration, invasion, proliferation, as well as induced cell cycle arrest and apoptosis. Significantly inhibitory effect on the size and number of sphere formed in genistein, daidzein and ERB-041 treated cells was also demonstrated. Moreover, genistein, daidzein and ERB-041 treatment reduced p-FAK, p-PI3K, p-AKT, p-GSK3β, p21 or cyclin D1 expression in ovarian cancer cells.ConclusionGenistein, daidzein and ERB-041 decreased ovarian cancer cell migration, invasion, proliferation and sphere formation, and induced cell cycle arrest and apoptosis with altered FAK and PI3K/AKT/GSK signaling and p21/cyclin D1 expression, suggesting their roles on ovarian cancer cell metastasis, tumorigenesis and stem-like properties and their potential as alternative therapies for ovarian cancer patients.

LncSOX4 serves an oncogenic role in the tumorigenesis of epithelial ovarian cancer by promoting cell proliferation and inhibiting apoptosis

Epithelial ovarian cancer is one of the primary causes of gynecological cancer mortality. Increasing evidence has suggested that long non-coding RNAs (lncRNAs) may serve a pivotal role in cancer development. To determine whether Lnc SRY-box 4 (SOX4), an lncRNA, promotes the self-renewal of liver tumor cells and contributes to the development of epithelial ovarian cancer, the present study investigated the expression of LncSOX4 in clinical epithelial ovarian cancer tissues and non-cancer controls by reverse transcription-quantitative polymerase chain reaction analysis. In addition, siRNA targeting LncSOX4 was designed and transfected into epithelial ovarian cancer cells to further assess the effect of knocking out LncSOX4 on cellular apoptosis, cell viability, proliferation and the cell cycle. The results demonstrated that the LncSOX4 expression level was significantly upregulated in epithelial ovarian cancer tissues (3.98 vs. 1.71, P<0.001). Silencing LncSOX4 in the SKOV3 and OVCAR3 cell lines significantly impaired cell proliferation (P<0.001). Cell cycle assays revealed that the proportion of cells in the G0/G1 phase increased significantly, whereas those in the S phase and G2/M phase decreased. Apoptosis rate additionally increased following knockdown of LncSOX4 in the two cell lines. Furthermore, it was observed that an increased LncSOX4 expression level was positively associated with larger tumor sizes, more advanced tumor grade and more distant metastases.

Long non-coding RNA NNT-AS1 contributes to cell proliferation, metastasis and apoptosis in human ovarian cancer.

Ovarian cancer is a markedly heterogeneous malignancy characterized by various histological subtypes. Molecular biomarkers have been indicated to serve significant functions in the early diagnosis and treatment of early-stage ovarian cancer. However, the detailed mechanism underlying the tumorigenesis of ovarian cancer remains unclear. The present study aimed to identify a novel long non-coding RNA in patients with ovarian cancer. Nicotinamide nucleotide transhydrogenase-antisense 1 (NNT-AS1) was markedly downregulated in patients with ovarian cancer and in cultured human ovarian cancer cells. Knockdown of NNT-AS1 in the human ovarian cancer cell lines HO-8910 and SK-OV-3 promoted colony formation and arrested the cell cycle at G0/G1 phase. Furthermore, Transwell demonstrated that the downregulation of NNT-AS1 increased cell migration and invasion by ~60 and 70%, respectively, in HO-8910 and SK-OV-3 cells. Furthermore, cell apoptosis was inhibited by the transfection of siNNT-AS1 in the two cell lines, whereas the relative activities of caspase-3 and caspase-9 were decreased. These results indicated a protective function of NNT-AS1 in human ovarian cancer, providing novel insights into the diagnosis and treatment of ovarian cancer in clinical settings.

Knockdown of MALAT1 enhances chemosensitivity of ovarian cancer cells to cisplatin through inhibiting the Notch1 signaling pathway

Long non-coding RNAs (lncRNAs) are critical regulators in chemoresistance of various tumors including ovarian cancer. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been reported to be upregulated and contributed to ovarian cancer tumorigenesis. The aim of this study was to explore the roles of MALAT1 and the underlying molecular regulatory mechanism in the chemoresistance of ovarian cancer cells. Our data demonstrated that MALAT1 and Notch1 mRNA were upregulated in ovarian cancer tissues, as well as cisplatin (CDDP)-resistant ovarian cancer cells. A positive correlation between MALAT1 and Notch1 mRNA expression was observed. MALAT1 knockdown significantly attenuated CDDP resistance, and enhanced CDDP-induced apoptosis in CDDP-resistant ovarian cancer cells. MALAT1 knockdown enhanced CDDP-induced apoptosis in vivo, as indicated by upregulation of Bax protein expression and downregulation of Bcl-2 protein expression. Additionally, MALAT1 knockdown inhibited the Notch1 pathway and ABCC1 expression in CDDP-resistant ovarian cancer cells. MALAT1 was demonstrated to interact with Notch1. Notch1 knockdown attenuated CDDP resistance, and downregulated the protein expression of ABCC1 in ovarian cancer cells. Taken together, our findings suggested that knockdown of MALAT-1 enhanced chemosensitivity of ovarian cancer cells to CDDP through inhibiting Notch1 signaling pathway.

A comprehensive analysis of the predicted targets of miR-642b-3p associated with the long non-coding RNA HOXA11-AS in NSCLC cells.

Long non-coding RNA HOXA11 antisense RNA (HOXA11-AS) has been previously reported to be involved in the tumorigenesis and progression of ovarian cancer and glioma. However, the function of HOXA11-AS in lung cancer remains unclear. Following the knockdown of HOXA11-AS in A549 cells, a microarray analysis was performed in order to detect the differences in microRNA (miRNA/miR) profiles. Subsequently, miR-642b-3p was selected for further analysis. Four miRNA target prediction algorithms were used to identify potential target genes of miR-642b-3p. Bioinformatics analyses, including Gene Ontology (GO), Kyoto Encyclopaedia of Genes and Genomes, protein-protein interactions (PPIs) and network analysis, were performed to investigate the potential functions, pathways and networks of the target genes. Furthermore, the differential expression of miR-642b-3p and its target genes between normal lung and non-small cell lung cancer (NSCLC) tissues was verified using The Cancer Genome Atlas (TCGA) database. Six target genes [zinc finger protein 350, heterogeneous nuclear ribonucleoprotein U, high mobility group box 1, phosphodiesterase 4D (PDE4D), synaptotagmin binding cytoplasmic RNA interacting protein and basic helix-loop-helix family member B9] of miR-642b-3p were predicted using all 4 algorithms. It was revealed that miR-642b-3p was overexpressed in adenocarcinoma and squamous cell carcinoma tissues compared with non-cancerous lung tissues based on the TCGA database. From the 6 target genes, PDE4D was downregulated in lung adenocarcinoma and squamous cell carcinoma tissues, and a weak negative correlation between HOXA11-AS and PDE4D was identified. The area under the curve of PDE4D was 0.905 [95% confidence interval (CI), 0.879–0.931] for patients with lung adenocarcinoma and 0.665 (95% CI, 0.606–0.725) for patients with squamous cell carcinoma. Additionally, GO analysis of the target genes revealed that miR-642b-3p was specifically involved in complex cellular pathways. The target gene RAN binding protein 2 possessed the highest degree of interactions in the PPI network (degree=40). It was hypothesized that HOXA11-AS may have a function in NSCLC by regulating the expression of miR-642b-3p and PDE4D, which laid the foundation for the further elucidation of the potential molecular mechanisms of NSCLC.

LncRNA PVT1 promotes ovarian cancer progression by silencing miR-214.

Objective:Emerging evidence indicates that long non-coding RNAs (lncRNAs) are critical in carcinogenesis and progression of ovarian cancer. This study aimed to explore the functions and molecular mechanisms of plasmacytoma variant translocation I (PVT1) in ovarian cancerMethods:PVT1 and miR-214 were detected by qRT-PCR assays in ovarian cancer tissues and cells. The cell proliferation, migration, and invasion abilities were detected by cell functional experiments, respectively. Western blot assay was performed to detect epithelial-mesenchymal transition (EMT) markers. MiR-214 expression regulated by PVT1 was studied by RNA immunoprecipitation (RIP) and chromatin immunoprecipitation (ChIP) assays.Results:The expression of PVT1 was up-regulated in ovarian cancer tissues and cell lines. Elevated PVT1 expression was associated with advanced stage and indicated poor prognosis for ovarian cancer patients. The knockdown of PVT1 impaired SKOV3 cell proliferation, migration, and invasion in vitro. The promotion of ovarian cancer progression by PVT1 involved in regulation of the epithelial-mesenchymal transition process and PVT1 interaction with EZH2 represses miR-214 expression in ovarian cancer cells. Conclusions:PVT1 plays an important role in ovarian cancer tumorigenesis, which might be as a novel diagnostic marker and therapeutic target for ovarian cancer.

LncRNA myocardial infarction-associated transcript promotes cell proliferation and inhibits cell apoptosis by targeting miR-330-5p in epithelial ovarian cancer cells.

IntroductionLong non-coding RNAs (lncRNAs) have been shown to have great importance in cancer development and progression. However, the mechanism of lncRNAs in epithelial ovarian cancer remains unclear. In the present study, we aimed to explore the role of the lncRNA myocardial infarction-associated transcript (MIAT) in epithelial ovarian cancer tumorigenesis.Material and methodsQuantitative real-time PCR (qRT-PCR) was used to determine MIAT expression in human epithelial ovarian cancer tissues and cell lines, and the effects of MIAT on cell proliferation and cell apoptosis were determined by CCK-8 assay or flow cytometry analysis. Dual-Luciferase Reporter assay and Western blot assay were used to explore the molecular mechanisms of MIAT in epithelial ovarian cancer cells progression.ResultsOur data showed that the expression of lncRNA MIAT was remarkably increased in human epithelial ovarian cancer tissues and cell lines (p < 0.05). High MIAT expression was associated with poor overall survival of epithelial ovarian cancer patients (p < 0.05). Function assays showed that knockdown of MIAT expression significantly inhibited epithelial ovarian cancer cell proliferation and promoted cell apoptosis in vitro (p < 0.05). Moreover, we revealed that MIAT might function as an endogenous miR-330-5p sponge to regulate the target gene of miR-330-5p in epithelial ovarian cancer progression.ConclusionsLncRNA MIAT was found to be a tumor oncogenic lncRNA in epithelial ovarian cancer tumorigenesis. LncRNA MIAT promoted cell proliferation and inhibited cell apoptosis by negative regulation of miR-330-5p in epithelial ovarian cancer cells. Our findings suggested that MIAT might act as a candidate prognostic biomarker and new therapeutic target for treating epithelial ovarian cancer patients.

LncRNA PCGEM1 Induces Ovarian Carcinoma Tumorigenesis and Progression Through RhoA Pathway

Background/Aims: Prostate cancer gene expression marker 1 (PCGEM1) is a long noncoding RNA (lncRNA) and is well known as a promoter in prostate cancer and osteoarthritis synoviocytes. However, the role PCGEM1 plays in epithelial ovarian cancer is unknown. Methods: PCGEM1 expression was examined in epithelial ovarian cancer and normal ovarian tissues using reverse transcription–PCR. Ovarian cancer cell phenotypes and genotypes were examined after PCGEM1 overexpression or downregulation in vitro; besides, the effects of PCGEM1 overexpression was also examined in vivo. Results: PCGEM1 expression level was higher in epithelial ovarian cancer tissues than in normal ovarian tissues and was positively associated with differentiation (Well vs. Mod/Poor). Upregulation of PCGEM1 induced cancer cell proliferation, migration, and invasion, but decreased cell apoptosis through upregulating RhoA, YAP (Yes-associated protein), MMP2 (matrix metalloproteinase 2), Bcl-xL, and P70S6K expression; while PCGEM1 downregulation had the opposite effect. The nude mouse xenograft assay demonstrated that PCGEM1 overexpression promoted tumor growth. Furthermore, silencing RhoA expression reversed the effect of PCGEM1 and significantly inhibited RhoA, YAP, MMP2, Bcl-xL, and P70S6K protein expression. Conclusion: In conclusion, we suggest that PCGEM1 may be an inducer in epithelial ovarian cancer tumorigenesis and progression by upregulating RhoA and the subsequent expression of YAP, P70S6K, MMP2, and Bcl-xL.

Inhibition of enhancer of zeste homolog 2 increases the expression of p16 and suppresses the proliferation and migration of ovarian carcinoma cells in vitro and in vivo.

Enhancer of zeste homolog 2 (EZH2) is a histone methyltransferase, which targets histone H3 lysine 27. Studies have reported that EZH2 is involved in the development of several types of tumor, including ovarian cancer. p16, a well-known cell cycle regulator, has been demonstrated to be a tumor suppressor gene in a variety of malignant cells. However, the regulatory association between EZH2 and p16 in ovarian cancer remains to be fully elucidated. The present study aimed to determine whether EZH2 is involved in the development of ovarian cancer by regulating the expression of p16. An EZH2 short hairpin RNA (shRNA) lentiviral vector was constructed and used for transducing A2780 and SKOV3 ovarian cancer cell lines. The expression levels of EZH2 and p16 in the ovarian cancer cells were detected using a reverse transcription-quantitative polymerase chain reaction and western blot analyses, respectively. The function of the inhibition of EZH2 in cell proliferation and migration were determined using a CCK-8 assay and Transwell assay. In addition, a nude mouse xenograft model was used to determine the function of EZH2 and p16 in the formation of ovarian cancer in vivo. The results revealed that the inhibition of EZH2 increased the expression of p16, and suppressed the proliferation and migration capabilities of ovarian cancer in vitro. The downregulated expression of EZH2 suppressed ovarian tumor formation in vivo. The results of the study revealed that p16 was negatively regulated by EZH2 in ovarian cancer, and that p16 and EZH2 are important in the tumorigenesis of ovarian cancer. EZH2 and p16 represent potential biomarkers for the diagnosis of ovarian cancer and as targets for ovarian cancer gene therapy.

Association of MGMT promoter methylation with tumorigenesis features in patients with ovarian cancer: A systematic meta-analysis.

BackgroundThe MGMT is a key tumor suppressor gene and aberrant promoter methylation has been reported in many cancers. However, the relationship between MGMT promoter methylation and ovarian cancer remains controversial. This meta‐analysis was first conducted to estimate the clinical significance of MGMT promoter methylation in ovarian carcinoma.MethodsLiterature search was performed in the PubMed, Embase, EBSCO and Cochrane Library databases. The pooled odds ratio (OR) and their corresponding 95% confidence interval (95% CI) were summarized.ResultsFinal 10 studies with 910 ovarian tissue samples were included in this meta‐analysis. MGMT promoter methylation was significantly higher in ovarian cancer than in normal ovarian tissues (OR = 4.13, 95% CI = 2.32–7.33, p < .001). The MGMT had a similar methylation status in cancer versus benign lesions and low malignant potential (LMP) samples (OR = 2.01, 95% CI = 0.67–6.04, p = .212; OR = 1.42, 95% CI = 0.46–4.40, p = .543; respectively). MGMT promoter methylation was correlated with pathological types in which it was significantly lower in serous cancer than in nonserous cancer (OR = 0.29, 95% CI = 0.14–0.59, p = .001). The methylation of the MGMT promoter was not associated with clinical stage and tumor grade (OR = 1.46, 95% CI = 0.71–3.02, p = .301; OR = 1.13, 95% CI = 0.51–2.46, p = .767; respectively).Conclusions MGMT promoter methylation may be correlated with the tumorigenesis of ovarian cancer. It was associated with tumor histotypes, but not correlated with clinical stage and tumor grade. More prospective studies with lager sample sizes are necessary in the future.

Role of the lncRNA ABHD11-AS1 in the tumorigenesis and progression of epithelial ovarian cancer through targeted regulation of RhoC

BackgroundThere is increasing evidence in support of the role of lncRNAs in tumor cell proliferation, differentiation and apoptosis.MethodsWe examined the expression of the lncRNA ABHD11-AS1 in epithelial ovarian cancer (EOC) tissues and normal ovarian tissues by real-time quantitative PCR (qRT-PCR). After inducing ABHD11-AS1 downregulation by small interfering RNA (siRNA) or ABHD11-AS1 overexpression by plasmid transfection, we examined the EOC cell phenotypes and expression of related molecules.ResultsExpression of the lncRNA ABHD11-AS1 in EOC tissues was higher than that in normal ovarian tissue. It was positively associated with the tumor stage (stage I/II vs. stage III/IV), and it was lower in the well-differentiated group than in the poorly/moderately differentiated group. Overexpression of ABHD11-AS1 in the ovarian cancer cell lines A2780 and OVCAR3 promoted ovarian cancer cell proliferation, invasion and migration, and inhibited apoptosis. Silencing of ABHD11-AS1 had the opposite effect. Subcutaneous injection of tumor cells in nude mice showed that ABHD11-AS1 could significantly promote tumor growth. In addition, intraperitoneal injection of tumor cells in the nude mice resulted in an increase in the metastatic ability of the tumor. Further, overexpression of ABHD11-AS1 upregulated the expression of RhoC and its downstream molecules P70s6k, MMP2 and BCL-xL. Silencing of ABHD11-AS1 had the opposite effect. The RNA pull-down assay showed that ABHD11-AS1 can combine directly with RhoC. Silencing of RhoC was found to inhibit the cancer-promoting effects of lncRNA ABHD11-AS1. Thus, it seems that RhoC is a major target of the lncRNA ABHD11-AS1.ConclusionsThis is the first study to demonstrate the role of RhoC in the tumor-promoting effects of the lncRNA ABHD11-AS1. The present findings shed light on new therapeutic targets for ovarian cancer treatment.

Knockdown of anion exchanger 2 suppressed the growth of ovarian cancer cells via mTOR/p70S6K1 signaling

Anion exchanger 2 (AE2, encoded by SLC4A2) is a sodium-independent chloride/bicarbonate transporter and implicated in the regulation of intracellular pH and membrane potential. Previous studies have linked AE2 to the tumorigenesis of various cancers. Here, AE2 was identified as an up-regulated protein in ovarian cancer tissues compared to adjacent non-tumor lesions based on quantitative proteomics analysis. AE2 mRNA was also overexpressed in human ovarian cancer samples, and that AE2 overexpression correlated with the shortened survival time of ovarian cancer patients. Short-hairpin RNA-mediated knockdown of AE2 in A2780 and SK-OV-R3 cells inhibited cell growth and induced cell cycle G1 phase arrest. In nude mice, its stable knockdown inhibited the tumorigenicity of A2780 cells. Gene set enrichment analysis on The Cancer Genome Atlas dataset identified that the cell cycle process and mTOR pathway were correlatively with the AE2 expression. Expression of key regulators of G1/S transition (Cyclin D1 and CDK4), and phosphorylation levels of p70S6K were notably reduced in AE2 knockdown cells. Moreover, experiments with mTOR inhibitor suggested that AE2 may promote cell cycle progression through mTOR/p70S6K1 pathway. Together, our results suggest up-regulated AE2 promotes ovarian cancer tumorigenesis by activating mTOR/p70S6K1 pathway and implicate the potential application of AE2 in cancer therapy.

Comparison of the protein expression of calpain-1, calpain-2, calpastatin and calmodulin between gastric cancer and normal gastric mucosa.

The understanding of molecular mechanisms that are involved in the development and the progression of gastric cancer (GC) are of importance for the diagnosis and treatment. The calpain system, which contains the calpains and the endogenous inhibitor, has been suggested as an important factor in the tumorigenesis and migration of colorectal adenocarcinoma, breast and ovarian cancer, and as a prognostic marker for GC. However, the expression level of calpain system proteins in GC and normal-appearing peritumoral gastric mucosa remain unknown. The present study investigated the expression of calpain-1 (CAPN1), calpain-2 (CAPN2), calpastatin and calmodulin (CaM) in GC and uninvolved gastric mucosa tissues with immunohistochemistry. Results demonstrated that CAPN2 protein level increased in GCs compared with normal tissues, while calpastatin and CaM protein level decreased. No evident alterations were observed for CAPN1. Although the protein expression of all these four proteins was not in association with the clinical variables of GC in the present study, higher calpain enzyme activity could be a negative prognostic marker, since calpains are responsible for the generation of active forms of certain proteins that facilitate the progression of cancer. The ratio of (CAPN1 × CAPN2)/(calpastatin × CaM) may serve as a potential index for diagnosis of GC.