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Experimental Validation Of Candidate Genes From Breast Cancer Transcriptome Study Involving Progesterone Treatment Open Access

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A recent study shows that a single progesterone injection prior to tumor removal increases survival rates in node-positive breast cancer patients. In order to understand the molecular mechanism underlying the increased survival rates in patients the Gene expression patterns of the breast tumors before the progesterone injection and after surgical removal of the tumor post the progesterone injection were comparatively analyzed. A precursor study leading to this project attempted to understand the molecular basis behind the successful clinical study. This precursor study analyzed the gene signature profiles of breast transcriptome pre (biopsy) and post (tumor removal surgery) progesterone treatment. The clinical samples obtained from three different major groups of breast cancer patients: Triple negative breast cancer (TNBC), Human epidermal growth factor receptor (HER2) positive and Estrogen receptor positive were subjected to whole transcriptome RNA sequencing and eventual validation of top 10 in RNA from tissue samples to RNA-sequencing at the McCormick Center. Computational analyses of resulting data led to identification of progesterone modulated target genes for its subsequent validation of 10 target genes by Quantitative Real-Time PCR analysis. In an attempt to understand contribution of specific signaling pathways and to discern if pro-survival effects of progesterone observed in patients was indeed mediated via the progesterone receptor pathway, I used in-vitro cell-based models. Our analysis showed that there were key tumor suppressor genes that were up regulated post progesterone treatment namely DUSP1, DUSP12, EGR3 and FOXP3, along with this EZH2 a known oncogene is significantly down regulated post progesterone treatment. A similar trend for the target genes was observed in two different progesterone receptor positive cell lines T47D and BT474 upon treatment with progesterone. Preliminary results from cell lines studies showed that these genes were up regulated at either 6hrs or 9hrs post progesterone treatment. Following the validation of the target genes post progesterone treatment in cell lines, we attempted to understand the key pathways modulated by these genes which could play a role in increasing survival rates of patients post-surgery. Bioinformatics analysis using top 4 candidates reviled that these genes regulate the cell growth and proliferation pathway. All the above mechanism help provide evidence for the role of progesterone in helping increasing survival rates in patients post-surgery, this can be achieved by decreasing cell proliferation and metastasis during tumor removal surgery and thus reduce recurrence of tumor post-surgery.

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