Association between -174 G/C promoter polymorphism of the interleukin-6 gene and progression of prostate cancer in North Indian population

The cellular alterations that give rise to cancer initiate changes in cytokine expression. Though IL-6 is known to play a major role in proliferation of tumor cells, IL-4 upregulates androgen receptors and prostate-specific antigen (PSA). The present study was undertaken to evaluate the association of IL-4 and IL-6 gene polymorphisms for the susceptibility to prostate cancer (PCa) risk. Our study included 200 controls and 200 histologically confirmed cases of PCa. Polymorphisms in IL-4 (intron 3, by VNTR analysis) and IL-6 (-174 G/C, by amplification refractory mutation system, i.e., ARMS-PCR) were genotyped in all the subjects. There was no significant association of IL-4 and IL-6 gene polymorphisms with the risk of PCa. Nevertheless, twofold risk with progression to bone metastasis (odds ratio = 2.09; 95% confidence interval = 1.16-3.75; p = 0.014) in PCa patients was observed. No association with other confounding factors such as PSA level, Gleason score, and lifestyle-associated risk factors like tobacco chewing and cigarette smoking was seen. Our study suggests that an IL-6 gene variant may be associated with prostate progression and bone metastasis.