Restricted Expression of miR-30c-2-3p and miR-30a-3p in Clear Cell Renal Cell Carcinomas Enhances HIF2a Activity

Inactivation of the von-Hippel Lindau ( VHL ) tumor suppressor gene occurs in 90% of human clear cell renal cell carcinomas (ccRCC) and leads to the stable expression of the hypoxia-inducible factors HIF1α and HIF2α. The constitutive expression of HIF1α in a majority of VHL defi cient tumors is counterintuitive, given that HIF1α functions as a tumor suppressor in ccRCC, whereas HIF2α clearly enhances tumor growth. We demonstrate here that miR-30c-2-3p and miR-30a-3p specifi cally bind and inhibit expression of HIF2A transcripts, and that the locus encoding miR-30c-2-3p and miR-30a-3p is selectively repressed in “H1H2” VHL -defi cient tumors expressing both HIF1α and HIF2α proteins. Inhibiting miR-30a-3p expression increases HIF2α levels in H1H2 ccRCC cells and promotes cellular proliferation, angiogenesis, and xenograft tumor growth. Our results indicate that miR-30c-2-3p and miR-30a-3p repression enhances HIF2α expression and suggests a mechanism whereby the tumorsuppressive effects of constitutive HIF1α expression are attenuated in VHL -defi cient H1H2 tumors. SIGNIFICANCE: HIF1α is constitutively expressed in a majority of VHL -defi cient ccRCCs, despite its tumor suppressor activity in these malignancies. This study demonstrates that repression of miR-30c2-3p / miR-30a-3p increases HIF2α levels to promote tumor growth, thereby ameliorating the inhibitory effects of HIF1α in ccRCCs. Cancer Discov; 4(1); 53–60. ©2013 AACR. See related commentary by Moch and Lukamowicz-Rajska, p. 22. Authors’ Affi liations: 1 Abramson Family Cancer Research Institute; 2 Howard Hughes Medical Institute; 3 Department of Cell and Developmental Biology; 4 Penn Molecular Profi ling Facility, Bioinformatics Group; 5 Department of Pathology and Laboratory Medicine; 6 Department of Cancer Biology; 7 Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; and 8 INSERM U1037, Institut Claudius Regaud, Rue du Pont St Pierre, Toulouse, France Note: Supplementary data for this article are available at Cancer Discovery Online (http://cancerdiscovery.aacrjournals.org/). Corresponding Authors: M. Celeste Simon, Scientifi c Director and Investigator, Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, 456 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160. Phone: 215-746-5532; Fax: 215-746-5511; E-mail: [email protected] ; and Priti Lal, Hospital of the University of Pennsylvania, Pathology and Laboratory Medicine, 3400 Spruce Street, Philadelphia, PA 19104-4283. E-mail: [email protected] doi: 10.1158/2159-8290.CD-13-0291 ©2013 American Association for Cancer Research. INTRODUCTION Clear cell renal cell carcinoma (ccRCC) is the most commonly diagnosed form of kidney cancer and accounts for the majority of renal cancer–related deaths. A characteristic feature of nearly 90% of sporadic ccRCCs is mutation or silencing of the von Hippel-Lindau ( VHL ) tumor suppressor gene ( 1 ). pVHL, the protein encoded by VHL , is a critical component of a ubiquitin ligase complex that regulates hypoxiainducible factor (HIF) accumulation ( 1 ). HIFs are heterodimeric on June 19, 2017. © 2014 American Association for Cancer Research. cancerdiscovery.aacrjournals.org Downloaded from Published OnlineFirst November 4, 2013; DOI: 10.1158/2159-8290.CD-13-0291