Data from Amplification of <i>PVT1</i> Contributes to the Pathophysiology of Ovarian and Breast Cancer

Abstract

<div>Abstract<p><b>Purpose:</b> This study was designed to elucidate the role of amplification at 8q24 in the pathophysiology of ovarian and breast cancer because increased copy number at this locus is one of the most frequent genomic abnormalities in these cancers.</p><p><b>Experimental Design:</b> To accomplish this, we assessed the association of amplification at 8q24 with outcome in ovarian cancers using fluorescence <i>in situ</i> hybridization to tissue microarrays and measured responses of ovarian and breast cancer cell lines to specific small interfering RNAs against the oncogene <i>MYC</i> and a putative noncoding RNA, <i>PVT1</i>, both of which map to 8q24.</p><p><b>Results:</b> Amplification of 8q24 was associated with significantly reduced survival duration. In addition, small interfering RNA–mediated reduction in either <i>PVT1</i> or <i>MYC</i> expression inhibited proliferation in breast and ovarian cancer cell lines in which they were both amplified and overexpressed but not in lines in which they were not amplified/overexpressed. Inhibition of <i>PVT1</i> expression also induced a strong apoptotic response in cell lines in which it was overexpressed but not in lines in which it was not amplified/overexpressed. Inhibition of <i>MYC</i>, on the other hand, did not induce an apoptotic response in cell lines in which <i>MYC</i> was amplified and overexpressed.</p><p><b>Conclusions:</b> These results suggest that <i>MYC</i> and <i>PVT1</i> contribute independently to ovarian and breast pathogenesis when overexpressed because of genomic abnormalities. They also suggest that <i>PVT1</i>-mediated inhibition of apoptosis may explain why amplification of 8q24 is associated with reduced survival duration in patients treated with agents that act through apoptotic mechanisms.</p></div>