miRNA Landscape in Stage I Epithelial Ovarian Cancer Defines the Histotype Specificities

Abstract

Purpose: Epithelial ovarian cancer (EOC) is one of the most lethal gynecologic diseases, with survival rate virtually unchanged for the past 30 years. EOC comprises different histotypes with molecular and clinical heterogeneity, but up till now the present gold standard platinum-based treatment has been conducted without any patient stratification. The aim of the present study is to generate microRNA (miRNA) profiles characteristic of each stage I EOC histotype, to identify subtype-specific biomarkers to improve our understanding underlying the tumor mechanisms.Experimental Design: A collection of 257 snap-frozen stage I EOC tumor biopsies was gathered together from three tumor tissue collections and stratified into independent training (n ¼ 183) and validation sets (n ¼ 74). Microarray and quantitative real-time PCR (qRT-PCR) were used to generate and validate the histotype-specific markers. A novel dedicated resampling inferential strategy was developed and applied to identify the highest reproducible results. mRNA and miRNA profiles were integrated to identify novel regulatory circuits.Results: Robust miRNA markers for clear cell and mucinous histotypes were found. Specifically, the clear cell histotype is characterized by a five-fold (log scale) higher expression of miR-30a and miR-30a à , whereas mucinous histotype has five-fold (log scale) higher levels of miR-192/194. Furthermore, a mucinous-specific regulatory loop involving miR-192/194 cluster and a differential regulation of E2F3 in clear cell histotype were identified. Conclusions: Our findings showed that stage I EOC histotypes have their own characteristic miRNA expression and specific regulatory circuits. Clin Cancer Res; 19(15); 4114-23. Ó2013 AACR.

Wiring miRNAs to pathways: a topological approach to integrate miRNA and mRNA expression profiles

“…Only samples with a RNA integrity number (RIN) larger than six and a Nanodrop A260:280 ratio between 1.8 and 2.1 were further processed and aliquots stored at −80°C until use. Array experiments were performed using standard procedures as previously published by (20). Briefly, 100 ng of total RNA was reverse transcribed into Cy3-labeled cRNA using LowInput QuickAmp labeling kit (Agilent Technologies, Palo Alto, CA, USA) and hybridized with a RNA labeling and hybridization kit according to the manufacturer's instructions (Agilent Technologies).…”

The Role of MicroRNAs in Ovarian Cancer

“…Calura et al analyzed miR profiles characteristic of each EOC histotype at stage 1 and found robust miR markers for clear cell and mucinous histotypes. The clear cell histotype is characterized by higher expression of miR-30a-5p and miR-30a-3p, whereas mucinous histotype displays higher levels of miR-192 and miR-194 [22]. Nam et al reported the miR expression profiles of 20 serous ovarian carcinomas using a miRNA microarray and compared them with normal samples [23].…”

MicroRNAs in gynecological cancers: Small molecules with big implications

“…Calura et al identified miRNAs that could be used as diagnostic markers [301]. These miRNAs could specifically discriminate clear cell and mucinous histotypes of OC-higher expression of miR-30a and miR-30a* was specific to clear cell carcinoma while that of miR-192/194 was specific to mucinous histotype.…”