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Sarah Filliben

Fellow – Sarah Filliben

Mentor – Weston Porter

Project – Role of Singleminded-2s in Tumorigenicity of Human Breast Cancer Cell Line

Objective – To determine the role and differentiation switch of the short splice variant of the basic helix-loop-helix Per-Arnt-Sim transcription factor Singleminded-2 (SIM2s) through examination of the tumorigenicity of the human breast cancer cell line.

Procedures – The cells were transduced with pSil and PLPCx lentiviral vectors to yield a knockout of SIM2s in the DCIS 3116 cells and an over-expression of SIM2s in DCIS PLPCx SIM2s cells. Proliferation assays were done to measure the rate of growth of the breast cancer cells. Matrigel invasion assays were performed to demonstrate the ability of the cells to invade the basement membrane. Quantitative PCR was conducted on the adhered cells.

Results – Our results confirm that loss of SIM2s will lead to an increase in stem cell-like and invasive characteristics as seen in the DCIS 3116 cells as compared to the controls. In contrast, we found that an increase in SIM2s expression, as seen in the DCIS PLPCx SIM2s cells, will have decreased stem-like activity and invasiveness and elevated epithelial-like characteristics, including up-regulation of E-cadherin, p21, and GATA3.

Conclusions and Clinical Relevance – These results demonstrate that SIM2s is required to maintain breast epithelial characteristics, whereas loss of SIM2s leads to a cancer stem-like phenotype, resulting in proliferation and invasion. Thus, SIM2s could be a therapeutic target for treatment of human breast cancer.