Research Summary
My laboratory is interested in understanding the roles of the Y chromosome genes and their X homologues in human development, physiology and diseases. Current interests focus on identifying the roles of sex chromosome genes in human cancers, particularly on prostate cancer, testicular germ cell tumors, and liver cancer; and in sexual dimorphic diseases, such as neurological disorders and cardiovascular disease. Various advanced genetic, genomic, proteomic, and transgenic mouse strategies are used in our research.
There are three categories of genes on the human Y chromosome: 1) those on the pseudoautosomal regions (PARs) which have identical homologues on the X chromosome; 2) those on the male-specific region on the Y chromosome (MSY), which have highly conserved homologues on the X chromosome and expressed widely in various tissues; and 3) those on the MSY, relatively diverged from their X homologues and specifically expressed in the testis. The first two categories of Y chromosome genes and their X homologues likely serve dosage-dependent and essential functions. Mosaic loss of the entire Y chromosome or inactivation of PAR and highly conserved MSY genes could result in dosage deficiency and disease predisposition. On the other hand, aberrant expression of Y-located and testis-specific genes in somatic tissues could exert male-specific effects on normal development, physiology and disease pathogeneses. Collectively such abnormalities could contribute genetically to various aspects of sex differences between males and females. Our research focuses on the ectopic activation of Y-linked genes, such as the sex-determining SRY gene and the spermatogonia factor TSPY, in male-biased diseases, including neurological disorders, cardiovascular disease, non-alcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma.
One major project focuses on the contrasting roles of the Y-located TSPY gene and its X homologue TSPX in various cancers and sex hormone-associated functions/diseases. TSPY is the gene for the gonadoblastoma locus on the Y chromosome (GBY), the only oncogenic locus on the male-specific chromosome. It serves normal functions as a spermatogenic factor. When aberrantly activated in incompatible cells, it behaves as an oncogene and promotes cell proliferation by stimulating the cyclin B-CDK1 phosphorylation activities, important for G2/M transition in the cell cycle. Significantly, TSPX, possesses contrasting property in suppressing the cyclin B-CDK1 activities, and maintaining the orderly G2/M transition and checkpoint integrity. Hence it is an X-linked tumor suppressor gene. Accordingly, aberrant activation of the Y-located TSPY oncogene and/or inactivation of the X-located TSPX tumor suppressor could collectively predispose males to oncogenesis. Importantly, both TSPY and TSPX could interact with the male sex hormone receptor, androgen receptor (AR) and its constitutively active variants, such as AR-V7. TSPY exacerbates and TSPX represses the transactivation of AR and AR-V7 functions in ligand-dependent and independent manners respectively. Further, TSPY is regulated by androgen via direct binding of AR and AR-V7 on its promoter, thereby supporting the notion that the male-specific oncogene TSPY and the male sex hormone receptors form a positive feedback loop in the oncogenesis of various male-specific and/or male-biased cancers and amplify synergistically their oncogenic actions. Since androgen, AR and AR-V7 play key roles in prostatic oncogenesis and advances to castration resistant prostate cancer (CRPC) and the lethal neuroendocrine prostate cancer, the differential actions of TSPY and TSPX on AR and AR-V7 suggest that they are important modulators for such lethal evolution of this important cancer in men. Our research in this project is designed to understand the molecular mechanisms of TSPY and TSPX actions and their translational applications for diagnosis, prognosis and treatments on male sex hormone-associated cancers, such prostate cancer and hepatocellular carcinoma.
Research Funding
October 1, 2019 - September 30, 2024 - Research Career Scientist Award , Principal Investigator . Sponsor: Department of Veterans Affairs, Sponsor Award ID: 1IK6BX004854
July 1, 2019 - June 30, 2024 - Molecular Mechanisms of a Male-Specific Positive Feedback Loop in Liver Cancer , Principal Investigator . Sponsor: Department of Veterans Affairs, Sponsor Award ID: 1IO1BX004446
September 1, 2019 - September 30, 2020 - Single-Cell Next-Generation Sequencing Library Preparation System , Principal Investigator . Sponsor: Department of Veterans Affairs, Sponsor Award ID: 1IS1BX005014-01
April 1, 1994 - September 30, 2019 - RESEARCH CAREER SCIENTIST AWARD , PRINCIPAL INVESTIGATOR . Sponsor: VA, Sponsor Award ID: RESEARCH CAREER SCIENTIST
Education
Harpur College, Binghamton University, B.A., 1973, Chemistry
MD Anderson Cancer Center-UTHealth, M.S., 1976, Cell Biology
MD Anderson Cancer Center-UTHealth, Ph.D., 1979, Genetics
University of California, San Francisco, Postdoctoral Fellowship,1979-1984, Human Genetics