Long noncoding RNA NEAT1, regulated by LIN28B, promotes cell proliferation and migration through sponging miR-506 in high-grade serous ovarian cancer.
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ABSTRACT:
SUBMITTER: Yong W
PROVIDER: S-EPMC6113267 | biostudies-literature | 2018 Aug
REPOSITORIES: biostudies-literature
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Project description:Molecular subtypes of serous ovarian cancer have been recently described. Using data from independent datasets including over 900 primary tumour samples, we show that deregulation of the Let-7 pathway is specifically associated with the C5 molecular subtype of serous ovarian cancer. DNA copy number and gene expression of HMGA2, alleles of Let-7, LIN28, LIN28B, MYC, MYCN, DICER1, and RNASEN were measured using microarray and quantitative reverse transcriptase PCR. Immunohistochemistry was performed on 127 samples using tissue microarrays and anti-HMGA2 antibodies. Fluorescence in situ hybridisation of bacterial artificial chromosomes hybridized to 239 ovarian tumours was used to measure translocation at the LIN28B locus. Short interfering RNA knockdown in ovarian cell lines was used to test the functionality of associations observed. Four molecular subtypes (C1, C2, C4, C5) of high-grade serous ovarian cancers were robustly represented in each dataset and showed similar pattern of patient survival. We found highly specific activation of a pathway involving MYCN, LIN28B, Let-7 and HMGA2 in the C5 molecular subtype defined by MYCN amplification and over-expression, over-expression of MYCN targets including the Let-7 repressor LIN28B, loss of Let-7 expression and HMGA2 amplification and over-expression. DICER1, a known Let-7 target, and RNASEN were over-expressed in C5 tumours. We saw no evidence of translocation at the LIN28B locus in C5 tumours. The reported interaction between LIN28B and Let-7 was recapitulated by siRNA knockdown in ovarian cancer cell lines. Our results associate deregulation of MYCN and downstream targets, including Let-7 and oncofetal genes, with serous ovarian cancer. We define for the first time how elements of an oncogenic pathway, involving multiple genes that contribute to stem cell renewal, is specifically altered in a molecular subtype of serous ovarian cancer. By defining the drivers of a molecular subtype of serous ovarian cancers we provide a novel strategy for targeted therapeutic intervention.
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Project description:High-grade serous ovarian cancer (HGSOC) harbours aberrant epigenetic features, including DNA methylation. In this study we delineate pathways and networks altered by DNA methylation and associated with HGSOC initiation and progression to a platinum-resistant state. By including tumours from patients who had been treated with the hypomethylating agent (HMA) guadecitabine, we also addressed the role of HMAs in treatment of HGSOC. Tumours from patients with primary (platinum-naïve) HGSOC (n = 20) were compared to patients with recurrent platinum-resistant HGSOC and enrolled in a recently completed clinical trial (NCT01696032). Human ovarian surface epithelial cells (HOSE; n = 5 samples) served as normal controls. Genome-wide methylation profiles were determined. DNA methyltransferase (DNMT) expression levels were examined by immunohistochemistry and correlated with clinical outcomes. Cancer-related and tumorigenesis networks were enriched among differentially methylated genes (DMGs) in primary OC vs. HOSE. When comparing platinum-resistant and primary tumours, 452 CpG island (CGI)-containing gene promoters acquired DNA methylation; of those loci, decreased (P < 0.01) methylation after HMA treatment was observed in 42% (n = 189 CGI). Stem cell pluripotency and cytokine networks were enriched in recurrent platinum-resistant OC tumours, while drug metabolism and transport-related networks were downregulated in tumours from HMA-treated patients compared to HOSE. Lower DNMT1 and 3B protein levels in pre-treatment tumours were associated with improved progression-free survival. The findings provide important insight into the DNA methylation landscape of HGSOC tumorigenesis, platinum resistance and epigenetic resensitization. Epigenetic reprogramming plays an important role in HGSOC aetiology and contributes to clinical outcomes.
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Project description:ObjectiveTo determine changes in the characteristics of low-grade serous ovarian cancer (LGSOC) and serous borderline ovarian tumor (serous-BOT) in a time-specific manner.MethodsWe conducted a population-based retrospective study examining the Surveillance, Epidemiology, and End Results Program from 1988 to 2000. Trends, demographics, and outcomes of 775 women with well-differentiated serous ovarian cancer, used as a surrogate for LGSOC, were compared to 3937 women with serous-BOT.ResultsIn the multivariable analysis, women with LGSOC were more likely to be older, have stage II-IV disease, and have undergone hysterectomy at surgery, but less likely to be a Western U.S. resident compared to those with serous-BOT (all, adjusted-P < 0.05). During the study period, the number of LGSOCs decreased by 25.9%, particularly stage I disease (37.6% relative decrease) compared to stage II-IV disease (21.1% relative decrease) (all, P < 0.05). With a median follow-up of 16.9 years, there was a decreasing trend in the 15-year overall survival rates among LGSOC (28.7% relative decrease, P = 0.056) but not in serous-BOT (2.5% relative increase, P = 0.416) as a whole cohort. The magnitude of hazard risk from all-cause death for women with LGSOC compared to those with serous-BOT increased by 68.9% from 1988 to 2000 (P < 0.001). LGSOC remained an independent prognostic factor for decreased overall survival compared to serous-BOT (adjusted-P < 0.05).ConclusionOur study suggests that the decreasing number and survival of LGSOC over time may be due to a diagnosis-shift from LGSOC to serous-BOT. Given the distinct characteristics and outcomes of LGSOC compared to serous-BOT, our study endorses the importance of making the correct diagnosis upfront. Whether this diagnostic-shift supports a hypothesis that serous-BOT is a precursor lesion of LGSOC merits further investigation.
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Project description:To examine clinicopathologic variables associated with survival among women with low-grade (grade 1) serous ovarian carcinoma enrolled in a phase III study.This was an ancillary data analysis of Gynecologic Oncology Group protocol 182, a phase III study of women with stage III-IV epithelial ovarian carcinoma treated with carboplatin and paclitaxel compared with triplet or sequential doublet regimens. Women with grade 1 serous carcinoma (a surrogate for low-grade serous disease) were included in the analysis.Among the 3,686 enrolled participants, 189 had grade 1 disease. The median age was 56.5 years and 87.3% had stage III disease. The median follow-up time was 47.1 months. Stratification according to residual disease after primary surgery was microscopic residual in 24.9%, 0.1-1.0 cm of residual in 51.3%, and more than 1.0 cm of residual in 23.8%. On multivariate analysis, only residual disease status (P=.006) was significantly associated with survival. Patients with microscopic residual had a significantly longer median progression-free (33.2 months) and overall survival (96.9 months) compared with those with residual 0.1-1.0 cm (14.7 months and 44.5 months, respectively) and more than 1.0 cm of residual disease (14.1 months and 42.0 months, respectively; progression-free and overall survival, P<.001). After adjustment for other variables, patients with low-grade serous carcinoma with measurable residual disease had a similar adjusted hazard ratio for death (2.12; P=.002) as their high-grade serous carcinoma counterparts with measurable disease (2.31; P<.001).Surgical cytoreduction to microscopic residual was associated with improved progression-free and overall survival in women with advanced-stage low-grade serous ovarian carcinoma.ClinicalTrials.gov, www.clinicaltrials.gov, NCT00011986.II.
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Project description:High-grade serous ovarian cancer (HGSOC) accounts for 70-80% of ovarian cancer deaths, and overall survival has not changed significantly for several decades. In this Opinion article, we outline a set of research priorities that we believe will reduce incidence and improve outcomes for women with this disease. This 'roadmap' for HGSOC was determined after extensive discussions at an Ovarian Cancer Action meeting in January 2015.
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Project description:Chemoresistance is a major challenge in cancer treatment. miR-506 is a potent inhibitor of the epithelial-to-mesenchymal transition (EMT), which is also associated with chemoresistance. We characterized the role of miR-506 in chemotherapy response in high-grade serous ovarian cancers. We used Kaplan-Meier and log-rank methods to analyze the relationship between miR-506 and progression-free and overall survival in The Cancer Genome Atlas (TCGA) (n = 468) and Bagnoli (n = 130) datasets, in vitro experiments to study whether miR-506 is associated with homologous recombination, and response to chemotherapy agents. We used an orthotopic ovarian cancer mouse model (n = 10 per group) to test the effect of miR-506 on cisplatin and PARP inhibitor sensitivity. All statistical tests were two-sided. MiR-506 was associated with better response to therapy and longer progression-free and overall survival in two independent epithelial ovarian cancer patient cohorts (PFS: high vs low miR-506 expression; Bagnoli: hazard ratio [HR] = 3.06, 95% confidence interval [CI] = 1.90 to 4.70, P < .0001; TCGA: HR = 1.49, 95% CI = 1.00 to 2.25, P = 0.04). MiR-506 sensitized cells to DNA damage through directly targeting the double-strand DNA damage repair gene RAD51. Systemic delivery of miR-506 in 8-12 week old female athymic nude mice statistically significantly augmented the cisplatin and olaparib response (mean tumor weight ± SD, control miRNA plus cisplatin vs miR-506 plus cisplatin: 0.36±0.05g vs 0.07±0.02g, P < .001; control miRNA plus olaparib vs miR-506 plus olaparib: 0.32±0.13g vs 0.05±0.02g, P = .045, respectively), thus recapitulating the clinical observation. MiR-506 is a robust clinical marker for chemotherapy response and survival in serous ovarian cancers and has important therapeutic value in sensitizing cancer cells to chemotherapy.
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Project description:BackgroundAberrant expression of microRNAs (miRNAs) contributes to the development of high grade serous ovarian cancer (HGSOC). However, the molecular mechanism by which miRNA-585-3p mediates high-grade serous ovarian carcinogenesis is unclear. This study aims to investigate the specific mechanism of action of miR-585-3p in HGSOC.MethodsExpression of miR-585-3p in HGSOC tissues and cell lines was detected by qRT-PCR. Cell viability and migration were detected using MTT and transwell system. The expression of target genes and target proteins of miR-585-3p was detected by dual luciferase reporter assay and western blot.ResultsThe expression of miR-585-3p was significantly lower in HGSOC tissues and cells than in normal ovarian tissues and cell lines. In HGSOC tissues, CAPN9 expression was inversely correlated with miR-585-3p expression. MiR-585-3p inhibited the proliferation and migration of HGSOC cells. MiR-585-3p bound to the 3'-untranslated region (UTR) of CAPN9 and inhibits CAPN9 expression. Overexpression of CAPN9 reduced the inhibitory effect of miR-585-3p in HGSOC cells.ConclusionsmiR-585-3p is significantly down-regulated in HGSOC tissues and cell lines. MiR-585-3p inhibits the proliferation and migration of HGSOC cells by targeting CAPN9.
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