Sequence Variation in Mature MicroRNA-499 Confers Unfavorable Prognosis of Lung Cancer Patients Treated with Platinum-Based Chemotherapy.

PURPOSE This study was implemented to investigate the associations between SNP in mature microRNA (miRNA) sequence and lung cancer prognosis and to verify the function of those SNP. EXPERIMENTAL DESIGN Eight SNPs (rs3746444T>C in hsa-mir-499, rs4919510C>G in hsa-mir-608, rs13299349G>A in hsa-mir-3152, rs12220909G>C in hsa-mir-4293, rs2168518G>A in hsa-mir-4513, rs8078913T>C in hsa-mir-4520a, rs11237828T>C in hsa-mir-5579, and rs9295535T>C in hsa-mir-5689) were analyzed in a southern Chinese population with 576 patients with lung cancer, and the significant results were validated in two additional cohorts of 346 and 368 patients, respectively. A series of experiments were performed to evaluate the relevancies of those potentially functional SNPs. RESULTS We found that the microRNA-499 rs3746444T>C polymorphism exhibited a consistently poor prognosis for patients with lung cancer in the discovery set [HR, 1.24; 95% confidence interval (CI), 1.02-1.49; P = 0.028], in the validation set I (HR, 1.31; 95% CI, 1.01-1.71; P = 0.048) and in the validation set II (HR, 1.45; 95% CI, 1.12-1.86; P = 0.004). The adverse effect of CT/CC variants was more remarkable in patients receiving platinum-based chemotherapy. Further functional assays demonstrated that the rs3746444C variant allele influences the expression of several cancer-related genes and affects lung cancer cells' proliferation and tumor growth in vivo and in vitro via the cisplatinum resistance. CONCLUSION Our findings suggested that the rs3746444T>C polymorphism in mature miR-499 sequence could contribute to poor prognosis by modulating cancer-related genes' expression and thus involve tumorigenesis and anti-chemotherapy, which may be a useful biomarker to predict lung cancer patients' prognosis.