Abstract 2138: Functional characterization of the 19q12 amplicon in grade 3 breast cancers

Abstract

Abstract Grade III (GIII) invasive ductal carcinomas of no special type (IDC-NST) comprise up to 60% of all invasive breast cancers and have an aggressive clinical behavior. We have previously identified 19q12 amplification in a subgroup of estrogen receptor (ER)-negative HER2 amplified (4%) and basal-like (16%) subtypes of breast cancer. This amplicon comprises 9 genes, including cyclin E1 (CCNE1), which has been proposed as its driver due to a strong association with gene over-expression. The aims of this study were to identify functionally the genes within the 19q12 amplicon whose expression is required for the survival of cancer cells harboring this amplification. We analyzed a series of 48 micro-dissected GIII IDC-NSTs using high-resolution microarray CGH and mRNA expression arrays and identified 19q12 amplification in 7.6% of ER negative GIII tumors. Of the 9 genes mapping to the smallest region of amplification, UQCRFS1, POP4, C19ORF12, CCNE1 and C19ORF2 were significantly over-expressed when amplified (P<0.05). Breast cancer cell lines with (MDAMB157 and HCC1569) and without (Hs578T, MCF7, MDAMB231 and ZR75.1) 19q12 amplification were screened with an RNAi library targeting the 9 genes mapping to the smallest region of amplification on 19q12. Individual short interfering RNA (siRNA) SMARTpools targeting these genes were plated in 96-well plates and cell viability was assessed after 9 days using CellTiter-Glo Luminescent Cell viability assay. Silencing of POP4, PLEKHF1, ZNF536 and ZNF537 selectively inhibited cell viability in 19q12-amplified cells compared to control cells. CCNE1 silencing was neither selectively lethal to cells harboring 19q12 amplification, nor lethal in all cells with this amplification. Our results demonstrate that expression of POP4, PLEKHF1, ZNF536 and ZNF537 is required for the survival of cancer cells displaying their amplification and suggest that the 19q12 amplicon may harbor more than one ‘driver’. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2138.