Research

Regulation of microRNA biosynthesis and expression in 2102Ep embryonal carcinoma stem cells is mirrored in ovarian serous adenocarcinoma patients

Michael F Gallagher^1,2* , Richard J Flavin^4* , Salah A Elbaruni^1,2* , Jamie K McInerney^1,2 , Paul C Smyth¹ , Yvonne M Salley^1,2 , Sebastian F Vencken^1,2 , Sharon A O'Toole³ , Alexandros Laios³ , Mathia YC Lee⁵ , Karen Denning¹ , Jinghuan Li¹ , Sinead T Aherne¹ , Kai Q Lao⁶ , Cara M Martin^1,2 , Orla M Sheils¹ and John J O'Leary^1,2

¹  Department of Histopathology, University of Dublin, Trinity College, Institute of Molecular Medicine, St James's Hospital, Dublin 8, Ireland

²  Department of Pathology, Coombe Women and Infants University Hospital, Dublin 8, Ireland

³  Department of Obstetrics and Gynaecology, University of Dublin, Trinity College, Institute of Molecular Medicine, St James's Hospital, Dublin 8, Ireland

⁴  The Centre for Molecular Oncologic Pathology, The Dana Faber Cancer Institute, Boston, MA02115, USA

⁵  NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore

⁶  Applied Biosystems, 850 Lincoln Centre Dr, Foster City, CA 94404, USA

author email corresponding author email* Contributed equally

Journal of Ovarian Research 2009, 2:19doi:10.1186/1757-2215-2-19

Published:	16 December 2009

Abstract

Background

Tumours with high proportions of differentiated cells are considered to be of a lower grade to those containing high proportions of undifferentiated cells. This property may be linked to the differentiation properties of stem cell-like populations within malignancies. We aim to identify molecular mechanism associated with the generation of tumours with differing grades from malignant stem cell populations with different differentiation potentials. In this study we assessed microRNA (miRNA) regulation in two populations of malignant Embryonal Carcinoma (EC) stem cell, which differentiate (NTera2) or remain undifferentiated (2102Ep) during tumourigenesis, and compared this to miRNA regulation in ovarian serous carcinoma (OSC) patient samples.

Methods

miRNA expression was assessed in NTera2 and 2102Ep cells in the undifferentiated and differentiated states and compared to that of OSC samples using miRNA qPCR.

Results

Our analysis reveals a substantial overlap between miRNA regulation in 2102Ep cells and OSC samples in terms of miRNA biosynthesis and expression of mature miRNAs, particularly those of the miR-17/92 family and clustering to chromosomes 14 and 19. In the undifferentiated state 2102Ep cells expressed mature miRNAs at up to 15,000 fold increased levels despite decreased expression of miRNA biosynthesis genes Drosha and Dicer. 2102Ep cells avoid differentiation, which we show is associated with consistent levels of expression of miRNA biosynthesis genes and mature miRNAs while expression of miRNAs clustering to chromosomes 14 and 19 is deemphasised. OSC patient samples displayed decreased expression of miRNA biosynthesis genes, decreased expression of mature miRNAs and prominent clustering to chromosome 14 but not 19. This indicates that miRNA biosynthesis and levels of miRNA expression, particularly from chromosome 14, are tightly regulated both in progenitor cells and in tumour samples.

Conclusion

miRNA biosynthesis and expression of mature miRNAs, particularly the miR-17/92 family and those clustering to chromosomes 14 and 19, are highly regulated in both progenitor cells and tumour samples. Strikingly, 2102Ep cells are not simply malfunctioning but respond to differentiation specifically, a mechanism that is highly relevant to OSC samples. Our identification and future manipulation of these miRNAs may facilitate generation of lower grade malignancies from these high-grade cells.