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Primary and recurrent ovarian high-grade serous carcinomas display similar microRNA expression patterns relative to those of normal ovarian tissue.

ABSTRACT: Most patients with epithelial ovarian cancer eventually die due to recurrence. However, little is known about the microRNA (miRNA) expression pattern and its involvement in recurrent ovarian cancer. We analyzed miRNA expression profiles related to the recurrence of advanced ovarian high-grade serous carcinoma (HGSC) using miRNA microarrays. Between May 2006 and December 2012, 37 ovarian HGSC patients underwent secondary cyto-debulking surgery at recurrence. Among them, only 8 pairs of primary and recurrent tumor samples were deemed to be adequate for analysis. The expression profiles of primary ovarian HGSC compared with normal ovarian tissue were significantly consistent with those of recurrent ovarian HGSC compared with normal ovarian tissue (correlation coefficient = 0.81, P = 0.0078). Among 31 miRNAs that increased by more than 4-fold in primary tumors compared with normal ovarian tissue, 27 were also significantly increased in recurrent tumor samples. Likewise, among 35 miRNAs that decreased by more than 4-fold in primary tumors compared with normal ovarian tissue, 34 were also significantly decreased in recurrent tumor samples. We identified 60 miRNAs that were significantly increased in recurrent serous ovarian carcinoma compared with primary tumor tissue, including miR-630, miR-370, and miR-575. Additionally, 52 miRNAs were significantly decreased in recurrent samples, including miR-509-3p, miR-514a-3p, and miR-506-3p. Our results demonstrate that primary and recurrent ovarian HGSC displayed similar miRNA expression patterns. Nevertheless, altered miRNA expression could be implicated in the recurrence of ovarian HGSC, and further study is needed to validate these data in independent cases using a homogeneous methodology.

SUBMITTER: Nam EJ

PROVIDER: S-EPMC5342571 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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Primary and recurrent ovarian high-grade serous carcinomas display similar microRNA expression patterns relative to those of normal ovarian tissue.

Nam Eun Ji EJ Kim Sunghoon S Lee Taek Sang TS Kim Hee Jung HJ Lee Jung Yun JY Kim Sang Wun SW Kim Jae Hoon JH Kim Young Tae YT

Oncotarget 20161001 43

Most patients with epithelial ovarian cancer eventually die due to recurrence. However, little is known about the microRNA (miRNA) expression pattern and its involvement in recurrent ovarian cancer. We analyzed miRNA expression profiles related to the recurrence of advanced ovarian high-grade serous carcinoma (HGSC) using miRNA microarrays. Between May 2006 and December 2012, 37 ovarian HGSC patients underwent secondary cyto-debulking surgery at recurrence. Among them, only 8 pairs of primary an ...[more]

PMID: 27655640

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Project description:BackgroundOvarian low-grade serous carcinoma (LGSC) has fewer mutations than ovarian high-grade serous carcinoma (HGSC) and a less aggressive clinical course. However, an overwhelming majority of LGSC patients do not respond to conventional chemotherapy resulting in a poor long-term prognosis comparable to women diagnosed with HGSC. KRAS and BRAF mutations are common in LGSC, leading to clinical trials targeting the MAPK pathway. We assessed the stability of targetable somatic mutations over space and/or time in LGSC, with a view to inform stratified treatment strategies and clinical trial design.MethodsEleven LGSC cases with primary and recurrent paired samples were identified (stage IIB-IV). Tumor DNA was isolated from 1-4 formalin-fixed paraffin-embedded tumor blocks from both the primary and recurrence (n = 37 tumor and n = 7 normal samples). Mutational analysis was performed using the Ion Torrent AmpliSeqTM Cancer Panel, with targeted validation using Fluidigm-MiSeq, Sanger sequencing and/or Raindance Raindrop digital PCR.ResultsKRAS (3/11), BRAF (2/11) and/or NRAS (1/11) mutations were identified in five unique cases. A novel, non-synonymous mutation in SMAD4 was observed in one case. No somatic mutations were detected in the remaining six cases. In two cases with a single matched primary and recurrent sample, two KRAS hotspot mutations (G12V, G12R) were both stable over time. In three cases with multiple samplings from both the primary and recurrent surgery some mutations (NRAS Q61R, BRAF V600E, SMAD4 R361G) were stable across all samples, while others (KRAS G12V, BRAF G469V) were unstable.ConclusionsOverall, the majority of cases with detectable somatic mutations showed mutational stability over space and time while one of five cases showed both temporal and spatial mutational instability in presumed drivers of disease. Investigation of additional cases is required to confirm whether mutational heterogeneity in a minority of LGSC is a general phenomenon that should be factored into the design of clinical trials and stratified treatment for this patient population.

Project description:Ovarian tumors of low malignant potential and low-grade ovarian serous carcinomas are thought to represent different stages on a tumorigenic continuum and to develop along pathways distinct from high-grade ovarian serous carcinoma. We performed gene expression profiling on three normal human ovarian surface epithelia samples, and 10 low-grade and 10 high-grade ovarian serous carcinomas. Analysis of gene expression profiles of these samples has identified 80 genes upregulated and 232 genes downregulated in low-grade ovarian serous carcinomas. PAX2 was found to be one of the most upregulated genes in low-grade ovarian serous carcinoma. The upregulation of PAX2 was validated by real-time quantitative RT-PCR, western blot and immunohistochemical analyses. Real-time RT-PCR showed a statistically significant difference in PAX2 mRNA expression (expressed as fold change in comparison to normal human ovarian surface epithelia) among ovarian tumors of low malignant potential (1837.38, N=8), low-grade (183.12, N=17), and high-grade (3.72, N=23) carcinoma samples (P=0.015). Western blot analysis revealed strong PAX2 expression in ovarian tumors of low malignant potential (67%, N=3) and low-grade carcinoma samples (50%, N=10) but no PAX2 protein expression in high-grade carcinomas (0%, N=10). Using immunohistochemistry, tumors of low malignant potential (59%, N=17) and low-grade carcinoma (63%, N=16) samples expressed significantly stronger nuclear staining than high-grade ovarian carcinoma samples (9.1%, N=263). Furthermore, consistent with earlier immunohistochemical findings, PAX2 expression was expressed in the epithelial cells of fallopian tubes but not in normal ovarian surface epithelial cells. Our findings further support the two-tiered hypothesis that tumors of low malignant potential and low-grade ovarian serous carcinoma are on a continuum and are distinct from high-grade ovarian carcinomas. In addition, the absence of PAX2 expression in normal ovarian epithelia but expression in fallopian tube fimbria and ciliated epithelial inclusions would suggest the potential development of tumors of low malignant potential and of low-grade ovarian serous carcinomas from secondary Müllerian structures.

Project description:While TP53 mutation is widely considered to be a defining feature of tubo-ovarian high-grade serous carcinoma (HGSC), rare TP53-mutation-negative cases have been reported. To gain further insight into this rare subset, a retrospective review was conducted on 25 TP53-wildtype tubo-ovarian HGSCs, constituting 2.5% of 987 HGSCs profiled by the MSK-IMPACT sequencing platform. Consistent with serous differentiation, positive staining for Pax8 and WT1 was present in virtually all TP53-wildtype HGSCs. Other characteristic features of HGSC, such as serous tubal intraepithelial carcinoma, or genetic alterations of CCNE1 and BRCA1/2 were identified in these tumors, furthering supporting their classification as bona fide HGSC, despite lacking TP53 mutations. Overall, the level of chromosomal instability of TP53-wildtype HGSCs was intermediate between low-grade serous carcinoma (LGSC) and TP53-mutated HGSC. Morphologic assessment by observers blinded to mutation status revealed a significant subset of tumors with Grade 2 nuclear atypia (which exceeds the degree of atypia allowed for LGSC, but less than typically encountered for HGSC) combined with micropapillary features (6/19, 32%, chemotherapy-naive TP53-wildtype HGSCs compared to 0/21, 0%, TP53-mutated HGSCs; p = 0.007). Some TP53-wildtype HGSCs harbored driver mutations in KRAS (n = 3), BRAF (n = 1) or NRAS (n = 2). Overall, 10 (40%) cases had "LGSC-like" morphology (i.e., Grade 2 nuclear atypia and micropapillary features) and/or RAS/RAF mutation, and most of these showed a wildtype p53 pattern of expression by immunohistochemistry (7/9, 78%). The remaining TP53-wildtype HGSCs (n = 15, 60%) exhibited severe nuclear atypia (Grade 3) and were morphologically indistinguishable from conventional TP53-mutated HGSC. Despite lacking genetic alterations of TP53, these "usual HGSC-like" tumors often showed evidence of p53 dysfunction, including downregulation of expression ('null' or equivocal p53 staining in 9/14, 64%) or MDM2 amplification (n = 2). Our results support the existence of TP53-wildtype HGSCs, which comprise a heterogeneous group of tumors which may arise via distinct pathogenic mechanisms.

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Primary and recurrent ovarian high-grade serous carcinomas display similar microRNA expression patterns relative to those of normal ovarian tissue.

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Primary and recurrent ovarian high-grade serous carcinomas display similar microRNA expression patterns relative to those of normal ovarian tissue.

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