Project Title: Determining the role of genetic variants linked to PIK3CA and metabolic regulators in breast cancer
Project Mentor: Amanda Toland – Cancer Biology and Genetics
The PI3K/AKT/mTOR pathway is central to cancer proliferation and has a wide range of effects including apoptosis, migration, and glucose metabolism in various cancer types. Breast cancer, in particular, has activation of this pathway through oncogenic mutations in the PIK3CA gene, informing potential treatments and therapies. A phenomenon connected to the PI3K pathway is the Warburg effect, a tendency for cancer cells to use glycolysis for energy, even under aerobic conditions. Within the well-described PI3K pathway, there is a lack of understanding regarding the changes in tumor metabolism caused by PIK3CA mutations, as well as potential effects of PIK3CA mutations when combined with other mediators in glycolysis. In preliminary work, I conducted an in silico search of a list of germline genetic variants associated with the PIK3CA mutation status in breast cancer for relevance to genes involved in glucose metabolism pathways. One gene identified was KDM8 (also known as JMJD5), which is 30kb from rs4493040, a single nucleotide variant (SNV) identified in our lab as associating with PIK3CA mutation status. Existing data shows that rs4493040 maps to a region with enhancer activity in breast cancer cell lines and mammary epithelial cells. KDM8 is a co-activator of HIF-1A, an inducible hypoxia regulator linked to expression of glycolytic genes. Similarly, PI3K is a significant regulator of HIF-1A through mTOR. Based on these studies, we hypothesize that the rs4493040 variant impacts KDM8/JMJD5 gene expression and subsequent HIF-1A activation. Additionally, we expect that KDM8 levels will act synergistically with PIK3CA mutations to enhance HIF-1A metabolism gene targets in glycolysis. Here, we aim to test the correlation and impact of effects of the rs4493040 variant on KDM8 expression through luciferase assays and chromatin immunoprecipitation (ChIP) studies. We hope to demonstrate a synergistic effect between the PI3K pathway and the KDM8 gene in vitro in existing MCF10A breast epithelial cells with and without CRISPR-induced PIK3CA mutations to test the association with the HIF-1A complex and expression of glycolytic genes. From the characterization of these mutations and pathway alterations, we hope to better understand tumor biology and metabolism to identify therapeutic targets for breast cancer treatment.