Prostate cancer incidence and mortality rates are higher in African-American (AA) than in European-American (EA) men. The main objective of this study was to elucidate the role of miR-130b as a contributor to prostate cancer health disparity in AA patients. We also determined whether miR-130b is a prognostic biomarker and a new therapeutic candidate for AA prostate cancer. A comprehensive approach of using cell lines, tissue samples, and the TCGA database was employed. We performed a series of functional assays such as cell proliferation, migration, invasion, RT2-PCR array, qRT-PCR, cell cycle, luciferase reporter, immunoblot, and IHC. Various statistical approaches such as Kaplan–Meier, uni-, and multivariate analyses were utilized to determine the clinical significance of miR-130b. Our results showed that elevated levels of miR-130b correlated with race disparity and PSA levels/failure and acted as an independent prognostic biomarker for AA patients. Two tumor suppressor genes, CDKN1B and FHIT, were validated as direct functional targets of miR-130b. We also found race-specific cell-cycle pathway activation in AA patients with prostate cancer. Functionally, miR-130b inhibition reduced cell proliferation, colony formation, migration/invasion, and induced cell-cycle arrest. Inhibition of miR-130b modulated critical prostate cancer–related biological pathways in AA compared with EA prostate cancer patients. In conclusion, attenuation of miR-130b expression has tumor suppressor effects in AA prostate cancer. miR-130b is a significant contributor to prostate cancer racial disparity as its overexpression is a risk factor for poor prognosis in AA patients with prostate cancer. Thus, regulation of miR-130b may provide a novel therapeutic approach for the management of prostate cancer in AA patients.
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