Abstract A79: Elucidating the role of E2F2 transcription factor in mediating human breast cancer metastasis

Abstract

Abstract In human breast cancer metastasis, it is not the primary tumor that is the cause of mortality but metastasis to distant sites. Therefore, it is important to elucidate the biological mechanism that underlies the metastatic processes. To address this, we utilized bioinformatic methods in combination with biochemical assays and genetic studies. Specifically, we crossed a MMTV-Myc mouse model with various activator E2Fs mutants and found that the tumor incidence decreased in the MMTV-Myc mice crossed with E2F2 and E2F3 mutant background. Surprisingly, we also found that the loss of E2F2 sharply increased lung metastasis in MMTV-Myc mice. Here, we test whether these observations in mice translate to human breast cancer and identify the genes under the control of E2F2 transcription factor that are responsible for mediating breast cancer metastasis. To achieve these aims, we examined the probability of activation of the E2F2 transcription factors in human breast cancer. We calculated the probability of E2F2 activation and used this data to stratify the human breast cancer samples and their associated metastatic clinical data. We performed hierarchical clustering of human and mouse gene expression datasets and uncovered two clusters of human breast tumors in which E2F2 played distinctly different roles in mediating metastasis. The human breast cancer samples that clustered with our mouse gene expression data exhibited the same role for E2F2 whereby it increased time to distant metastasis. We then examined genes that were differentially regulated within this cluster and found that there was a set of genes that were associated with a difference in human metastasis survival times and with the E2F2 knockout in the mouse model. To further explore the mechanism by which E2F2 mediates human breast cancer metastasis, we have identified four genes asputative E2F2 target genes including KLK1, MYH2, PTPRD and TNNC2. We found that partial knockdown of KLK1 promotes the migratory capacity of MCF7 cell in vitro. In addition, partial knockdown of PTPRD affected cellular morphology, where they were found to grow in discreet clusters while having little effect on the migration capacity in a scratch assay. We are currently exploring the effects of MYH2 and TNNC2 ablation on these cells. Taken together, we have begun to elucidate the roles of E2F2 transcription factor in mediating breast cancer metastasis as well as establishing a mechanism by which E2F2 regulates metastasis. Citation Format: Inez Yuwanita, Danielle Barnes, Eran Andrechek. Elucidating the role of E2F2 transcription factor in mediating human breast cancer metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr A79.