A functional variant in miR-143 promoter contributes to prostate cancer risk.

MicroRNAs are important regulators in numerous cellular processes, including cell differentiation, proliferation, and apoptosis. Recently, miR-143 was identified as a tumor suppressor in prostate cancer (PCa). To explore the mechanism of dysregulation and anti-tumor function of miR-143 in PCa, we first found a single-nucleotide polymorphism rs4705342T>C in the promoter region of miR-143 through bioinformatics tools and then performed a case-control study including 608 PCa patients and 709 controls. Results suggested that subjects with TC/CC genotypes had significantly decreased risk of PCa compared with those with TT genotype (adjusted OR 0.68, 95 % CI 0.55-0.85). Further functional assays showed that the risk-associated T allele increased the protein-binding affinity and reduced the activity of the promoter compared with C allele. In addition, restoration of miR-143 by mimics in PCa cells significantly inhibited cell proliferation and migration and down-regulated the expression level of kallikrein-related peptidase 2 (KLK2) mRNA and protein. The miR-143-KLK2 axis was also confirmed by luciferase reporter assay in vitro. In conclusion, our findings demonstrate that there is the significant association between the functional promoter variant rs4705342T>C in miR-143 and PCa risk and newly describe the miR-143-KLK2 interaction which provided another potential mechanism for miR-143 anti-tumor function.