Maureen E. Murphy, Ph.D.

p53 is the most important gene in human cancer. Up to 60 percent of human tumors contain mutations in p53, making it the most frequently mutated gene in human cancer. In addition, germline mutations in p53 cause a syndrome called Li Fraumeni disease where people affected develop multiple tumors of the brain, breast, bone, and adrenal cortex before their second decade of life. Therefore, alterations that reduce p53 function have tremendous potential to increase cancer risk.

Unlike other tumor suppressor genes and oncogenes, p53 is unique because it possesses a number of coding region variants that differ in different ethnic populations. Our work has identified two coding region variants in p53 that exist in individuals of African descent. We find that these variants show impaired tumor suppressor function and may contribute to the increased cancer risk and reduced efficacy of cancer therapy, currently experienced by African Americans. Most recently, we have identified chemotherapeutic drugs that preferentially eradicate tumors that contain these African-centric variants of p53. A major goal in the laboratory is to improve the treatment of cancers from individuals of African descent.

HSP70 is a cancer-critical chaperone protein that allows tumor cells to survive under conditions of stress and aneuploidy by preventing proteotoxic stress. We identified a novel series of inhibitors for HSP70 that are potent and effective anti-cancer agents. More recently, we discovered that a significant fraction of HSP70 in tumors is localized to mitochondria. We modified our inhibitor to target mitochondrial HSP70, and found that this compound, which we call AP-4-139B, can effectively target melanoma tumors in mice, and can inhibit melanoma metastasis, with no evidence for toxicity to normal tissues. We also find that this compound extends the response of melanoma to current therapies like BRAF and MEK inhibitors. Our studies in this area seek to position our HSP70 inhibitors for eventual use in humans. These studies are done in collaboration with the Salvino laboratory at Wistar.