Identification and Functional Validation of Reciprocal microRNA–mRNA Pairings in African American Prostate Cancer Disparities

Abstract

Purpose African Americans (AA) exhibit higher rates of prostate cancer (PCa) incidence and mortality compared to European American (EA) men. In addition to socioeconomic influences, biological factors are believed to play a critical role in PCa disparities. We investigated whether population-specific and -enriched miRNA-mRNA interactions might contribute to PCa disparities. Experimental Design Integrative genomics was employed, combining miRNA and mRNA profiling, miRNA target prediction, pathway analysis and functional validation, to map miRNA-mRNA interactions associated with PCa disparities. Results We identified 22 AA-specific and 18 EA-specific miRNAs in PCa versus patient-matched normal prostate, and 10 ‘AA-enriched/-depleted’ miRNAs in AA PCa versus EA PCa comparisons. Many of these population-specific/-enriched miRNAs could be paired with target mRNAs that exhibited an inverse pattern of differential expression. Pathway analysis revealed epidermal growth factor receptor (EGFR or ERBB) signaling as a critical pathway significantly regulated by AA-specific/-enriched mRNAs and miRNA-mRNA pairings. Novel miRNA-mRNA pairings were validated by qRT-PCR, western blot and/or IHC analyses in PCa specimens. Loss/gain of function assays performed in population-specific PCa cell lines confirmed miR-133a/MCL1, miR-513c/STAT1, miR-96/FOXO3A, miR-145/ITPR2 and miR-34a/PPP2R2A as critical miRNA-mRNA pairings driving oncogenesis. Manipulating the balance of these pairings resulted in decreased proliferation and invasion, and enhanced sensitization to docetaxel-induced cytotoxicity in AA PCa cells. Conclusion Our data suggest that AA-specific/-enriched miRNA-mRNA pairings may play a critical role in the activation of oncogenic pathways in AA PCa. Our findings also suggest that miR-133a/MCL1, miR-513c/STAT1 and miR-96/FOXO3A may have clinical significance in the development of novel strategies for treating aggressive PCa.

Racial differences in microRNA and gene expression in hypertensive women

“…We observed that MCL1 mRNA is elevated in AAHT compared with AANT and WHT, and decreased in WHT compared with WNT. Consistent with our findings in AAs, male AA prostate cancer patients have higher levels of MCL1 mRNA and protein compared to white males35. That study also identified miR-133a as a negative regulator of MCL1 35.…”

“…Consistent with our findings in AAs, male AA prostate cancer patients have higher levels of MCL1 mRNA and protein compared to white males35. That study also identified miR-133a as a negative regulator of MCL1 35. miR-133a has previously been associated with hypertension17; however, miR-133a expression was not differentially-expressed in our cohort, suggesting that additional regulatory factors (e.g.…”

Racial disparities in prostate cancer a molecular perspective

“…Computational pathway analysis suggested that miRNA–mRNA pairs predict the enhanced activation of EGFR–PI3K–AKT signaling in AA compared with EA cancers. Loss of function of these miRNA–mRNA pairs in AA prostate cancer cells reduced their proliferation, aggressiveness and increased docetaxel-induced cytotoxicity, while their converse manipulation in EA cell lines enhanced their aggressive potential (41). …”

Alternative splicing promotes tumour aggressiveness and drug resistance in African American prostate cancer

“…Possible mechanisms that could drive differences in AS events include differential expression of trans -acting splicing factors47 and/or single-nucleotide polymorphisms in cis -acting splicing elements of alternatively spliced genes50. In fact, a number of splicing factor mRNAs appear to be overexpressed ( SRSF2 , SRSF7 ) in AA PCa compared with EA PCa910. Regarding the in-frame variants ( PIK3CD-L , FGFR3-L and TSC2-L ) detected in EA PCa, each conferred a less aggressive oncogenic phenotype compared with the corresponding in-frame variants detected in AA PCa ( PIK3CD-S , FGFR3-S and TSC2-S ).…”

“…The in vitro functional assays, including cell proliferation and invasion, were performed following siRNA transfections for 24 h. Cell proliferation and invasion assays were performed using 5-bromodeoxyuridine Cell Proliferation Assay kit (Calbiochem, Billerica, MA, USA) and the Matrigel Invasion Chambers (BD Biosciences, San Jose, CA, USA), respectively, as per the manufacturers’ protocol910.…”