The rs10993994 in the proximal MSMB promoter region is a functional polymorphism in Asian Indian subjects

BACKGROUND: The microseminoprotein gene encoding prostate secretory protein of 94 amino acids (PSP94) harbours a potential risk allele (rs10993994) for prostate cancer (PCa) in its promoter region. However, studies on rs10993994 have been sparse in Asian Indians. METHODS: The present study recruited a sample population of 44 benign prostatic hyperplasia patients, 33 PCa patients and 60 healthy participants, of which, participants without other confounding risk factors for PCa were retained. The serum PSP94 (sPSP94) levels were measured by a serum-based ELISA in an earlier study. A novel RFLP technique was developed to screen for rs10993994 which was validated with direct sequencing. RESULTS: Sequencing showed additional 4 SNPs (rs41274660, rs141211965, rs12770171, rs10669586) and 2 novel variants (GenBank accession nos. KM265191 and KM265192). In silico DNA topographical studies predicted that KM265192 would have higher cleavage intensity and more accessibility for binding of transcription factors. Even though, similar frequencies were observed for all the variants in all the three study groups, the risk allele ‘T’ (rs10993994) was seen to be associated with reduced PSP94 expression both at mRNA and protein level. Further, mRNA expression as studied by real-time PCR correlated positively with sPSP94 levels. Interestingly, CC genotype of rs10993994 showed highest sPSP94 levels in all the three study groups and was associated with Gleason score ≤7 in PCa patients. In contrast, TT genotype of rs10993994 was associated with lesser sPSP94 levels and with aggressiveness of PCa. CONCLUSION: rs10993994 was found to be a functional SNP in the studied Asian Indian population.