Abstract LB-208: Small interfering RNA library screen to identify therapeutic transcription factor.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Post-genomic analyses of major transcription factor families, in both malignant and non-malignant cell types, have resulted in a broader revision of understanding the biology of transcription factor families. A number of oncogenic transcription factors, such as activator protein (AP)-1, estrogen receptor(ER) and signal transducer and activator of transcription (STAT)-3/STAT-5, are overactivated in human carcinomas. Up to now, three main groups of transcription factors are known to be important in human cancer. Transcription factor-directed anticancer drug development has focused on membrane or cytosolic targeting of molecules acting as ligand receptors. Recent technologies, such as small interfering RNA (siRNA), have shifted transcription factor targeting toward a more sophisticated rationale to elucidate the mechanisms that govern gene expression by analyzing the functions of proteins commonly over-expressed in transformed and malignant cells. In this study, we've applied a cell spot microarray (CSMA) method which provides reproducible multi-parametric phenotypic readouts for large-scale gene knockdown genetic screens. A human transcription factor siRNA library including 350 transcription factor genes which were significantly overexpressed in human breast cancer was screened against 6 breast cancer cell lines including (Triple negative breast cancer, HER2 positive ER positive) SUM149, BT20, HCC1569, SKBR3, MDAMB361 and MCF7 for measuring cell proliferation using EdU incorporation, cell apoptosis with c-PARP staining. We ranked the candidate gene list by the change of the rate of EdU or level of c-PARP or the combination of both. Our data showed that the silencing of LHX1, BCL6, GABPA or SMAD1 increased the c-PARP levels in most of cell lines. The Knockdown of ZNF215, NFATC1, HOXD4 or ZNF169 reduced the levels of EdU staining. Selected siRNAs were then tested on more different breast cancer cell lines to confirm the spectrum of activity. In the near future, based on this pilot screen, a complete siRNA library of transcription factors including 1000 gene list will be tested on our panel of 50 breast cancer cell lines. Our screen will provide comprehensive information on the central role of transcription factor in breast cancer, and will lead to the identity of novel therapeutics selectively against transcription factors. Citation Format: Zhi Hu, Shenda Gu, Joe Gray, Juha Rantala. Small interfering RNA library screen to identify therapeutic transcription factor. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-208. doi:10.1158/1538-7445.AM2013-LB-208