Presenting Author University of the Incarnate Word
Breast cancer currently ranks second in leading causes of death in women in the United States. It is estimated that one in eight women will develop breast cancer over the course of their life, so finding treatment options for this disease is critical. Current treatment strategies include chemotherapy, radiation, and surgery, all of which can cause harmful side effects that can be damaging to the patient’s overall health. Furthermore, these strategies are not always effective, so personalized treatment has become an area of interest to those who are searching for alternative treatment options. With the current genome sequencing technology that is available, researchers are able to identify specific locations in the DNA that could be a potential target area for treatment. One of those locations is the Mediator subunit MED12 that has been shown to be mutated in up to 67% of breast cancer tumors. Our results from previous experiments show mutations in MED12 promote GLI3-dependent Sonic Hedgehog (SHH) signaling, thus indicating that tumor cells could potentially use this pathway to proliferate when MED12 is mutated. With these findings we hypothesize that MED12 mutations promote hyperactivated SHH signaling in breast cancer cells and that the compound Alisol B 23-acetate (AB23A), a natural triterpenoid, can target SHH signaling in these cells to suppress oncogenesis. To study the effects of MED12 mutation, the MCF-7 breast cancer cell line was infected with a lentivirus carrying a shRNA targeted against MED12. Most MED12 mutations in breast cancer cells lead to a loss of function in the protein, so we presume that a knockdown of MED12 would lead to similar presentation that is seen in tumors. To test for the effects of this knockdown on cell growth, proliferation assays were conducted which confirmed that MED12 knockdown promotes oncogenesis. Quantitative PCR was then conducted to determine the effects of MED12 on GLI3 target genes. Our results show that when MED12 is knocked down, there is an increase in the expression of GLI3 target genes. Next, MTT assays were performed to determine the effects of AB23A on both MCF-7 control and MCF-7 MED12 knockdown cells. These results indicate that AB23A does not affect the viability of MCF-7 control cells but does promote cell death in MCF-7 MED12 knockdown cells. Furthermore, through quantitative PCR analysis, we found that AB23A specifically promotes downregulation of GLI3 target genes, thus indicating that this compound likely targets the GLI3-dependent SHH signaling pathway. Overall, these results provide insight into AB23A as a potential therapeutic treatment for breast cancer with MED12 mutations.
