1. ¹Department of Histopathology, Trinity College Dublin, Dublin, Ireland
2. ²Department of Obstetrics and Gynaecology, Trinity College Dublin, Dublin, Ireland
3. ³Applied Biosystems, Foster City, CA, USA

Correspondence: Dr RJ Flavin, MB, FRCPath, Department of Histopathology, Phase 3 Trinity Centre for Health Sciences, St James's Hospital, James's Street, Dublin 8, Ireland. E-mail: flavinr@tcd.ie

Received 4 June 2008; Revised 1 July 2008; Accepted 2 July 2008; Published online 1 August 2008.

Abstract

MicroRNAs are a group of small non-coding RNAs approximately 22 nucleotides in length. Recent work has shown differential expression of mature microRNAs in human cancers. We characterized the alteration in expression of a select group of microRNAs in primary peritoneal carcinoma relative to matched cases of ovarian serous carcinoma. MicroRNA expression was analysed using semi-quantitative stem-loop RT-PCR on a set of 34 formalin-fixed paraffin-embedded samples. Protein expression of p53 and bcl-2 was quantified in the corresponding tissue microarray. We provide definitive evidence that there is downregulation of a select group of microRNAs in tumours meeting Gynaecological Oncology Group criteria for primary peritoneal carcinoma relative to ovarian serous carcinoma. Specifically, we show decreased p53 expression and downregulation of miR-195 and miR-497 from the microRNA cluster site at chromosome 17p13.1 in primary peritoneal carcinoma relative to ovarian serous carcinoma. miR-195 and miR-497 may have potential roles as tumour-suppressor genes in primary peritoneal tumourigenesis.