African American (AA) families have the highest risk of prostate cancer. However, the genetic factors contributing to prostate cancer susceptibility in AA families remain poorly understood. We performed whole-exome sequencing of one affected and one unaffected brother in an AA family with hereditary prostate cancer. The novel non-synonymous variants discovered only in the affected individuals were further analyzed in all affected and unaffected men in 20 AA-PC families. Here, we report one rare recurrent ADPRHL1 germline mutation (c.A233T; p.D78V) in four of the 20 families affected by prostate cancer. The mutation co-segregates with prostate cancer in two families and presents in two affected men in the other two families, but was absent in 170 unrelated healthy AA men. Functional characterization of the mutation in benign prostate cells showed aberrant promotion of cell proliferation, whereas expression of the wild-type ADPRHL1 in prostate cancer cells suppressed cell proliferation and oncogenesis. Mechanistically, the ADPRHL1 mutant activates PARP1, leading to an increased H2O2 or cisplatin-induced DNA damage response for prostate cancer cell survival. Indeed, the PARP1 inhibitor, olaparib, suppresses prostate cancer cell survival induced by mutant ADPRHL1. Given that the expression levels of ADPRHL1 are significantly high in normal prostate tissues and reduce stepwise as Gleason scores increase in tumors, our findings provide genetic, biochemical, and clinicopathological evidence that ADPRHL1 is a tumor suppressor in prostate tissue. A loss of function mutation in ADPRHL1 induces prostate tumorigenesis and confers prostate cancer susceptibility in high-risk AA families.
This study highlights a potential strategy for ADPRHL1 mutation detection in prostate cancer–risk assessment and a potential therapeutic application for individuals with prostate cancer in AA families.