Lab In The News
The Murphy Laboratory
The Murphy laboratory focuses on two cancer-critical proteins involved in tumor cell survival and death: HSP70 and p53. p53 is the most frequently mutated gene in human cancer and is widely regarded as the most important anti-cancer defense protein in the body. The lab studies genetic variants of the p53 gene that exist in different ethnic groups. This work seeks to understand the impact of these genetic variants on the increased cancer burden experienced by these groups. Work in the Murphy lab also aims to identify novel cancer therapies that are more effective on tumors that contain genetic variants of p53 that exist in African Americans and Ashkenazi Jewish populations to improve personalized medicine.
The HSP70 protein is highly expressed in the majority of human tumors but is largely undetectable in normal cells, making it an ideal cancer target. The Murphy lab uses a series of novel HSP70 inhibitors they have created for the therapy of human tumors, with focus on colorectal cancer and melanoma. They also seek to understand why tumors that express high levels of HSP70 are more aggressive and are associated with poorer prognosis.
Chunlei Shao, Ph.D.
David Stieg, Ph.D.
James “Fitz” Dougherty
The tumor suppressor p53
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 inhibitors for cancer therapy
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.
Powers, J., Pinto, E.M., Barnoud, T., Leung, J.C., Martynyuk, T., Kossenkov, A.V., Philips, A.H., Desai, H., Hausler, R., Kelly, G., et al. “A Rare TP53 Mutation Predominant in Ashkenazi Jews Confers Risk of Multiple Cancers.” Cancer Res. 2020 Sep 1;80(17):3732-3744.doi: 10.1158/0008-5472.CAN-20-1390. Epub 2020 Jul 16.
Singh, K.S., Leu, J.I., Barnoud, T., Vonteddu, P., Gnanapradeepan, K., Lin, C., Liu, Q., Barton, J.C., Kossenkov, A.V., George, D.L., et al. “African-centric TP53 Variant Increases Iron Accumulation and Bacterial Pathogenesis but Improves Response to Malaria Toxin.” Nat Commun. 2020 Jan 24;11(1):473. doi: 10.1038/s41467-019-14151-9.
Leu, J.I., Murphy, M.E., George, D.L. “Mechanistic Basis for Impaired Ferroptosis in Cells Expressing the African-centric S47 Variant of p53.” Proc Natl Acad Sci U S A. 2019 Apr 23;116(17):8390-8396. doi: 10.1073/pnas.1821277116. Epub 2019 Apr 8.
Barnoud, T., Budina-Kolomets, A., Basu, S., Leu, J.I., Good, M., Kung, CP., Liu, J., Liu, Q., Villanueva, J., Zhang, R., et al. “Tailoring Chemotherapy for the African-Centric S47 Variant of TP53.” Cancer Res. 2018 Oct 1;78(19):5694-5705. doi: 10.1158/0008-5472.CAN-18-1327. Epub 2018 Aug 16.
Murphy, M.E., Liu, S., Yao, S., Huo, D., Liu, Q., Dolfi, S.C., Hirshfield, K.M., Hong, CC., Hu, Q., Olshan, A.F., et al. “A functionally significant SNP in TP53 and breast cancer risk in African-American women.” NPJ Breast Cancer. 2017 Feb 27;3:5. doi: 10.1038/s41523-017-0007-9. eCollection 2017.
Luis J. Montaner, D.V.M., D.Phil.
Vice President, Scientific Operations
Associate Director for Shared Resources, Ellen and Ronald Caplan Cancer Center
Herbert Kean, M.D., Family Professor; Director, HIV-1 Immunopathogenesis Laboratory and Leader, HIV Research Program, Vaccine & Immunotherapy Center
Immunology, Microenvironment & Metastasis Program, Ellen and Ronald Caplan Cancer Center
Scientific Director, Humanized Models of Disease Facility