Immunotherapy of Prostate Cancer may Change mRNA Level of Virulence Factor Genes in E.Faecalis of Microflora

FDA has approved the immunotherapy for prostate cancer in 2010. Immunotherapy is the treatment of disease by inducing, enhancing, or suppressing an immune response and is well known as specific and noninvasive method for cancer treatment; but side effects of this method are not clarified. Enterococci are Gram positive coccies, which are intestinal commensals and microflora of humans and other mammalians. Most enterococcal infections in human such as gastroenteritis, intestinal infections, prostatitis and endocarditic are causing by Enterococcus faecalis. Present study aimed to evaluate the side effects of immunotherapy on E. faecalis of microflora. Methods: mRNA level of 10 virulent genes (gelE, esp, asa1, aggA, cylA, cylB, cylM, Eep, efaA and enlA) which are involved in pathogenesis of E. faecalis, were examined in stool samples of two groups of men by quantitative real time PCR. Group A includes 359 prostate cancer patients and group B contains 360 normal family members of patients, which were lived with them at least for recent 12 months. Gene expression assessments in patient’s group were operated before start and after finishing a six weeks’ period of cancer vaccines immunotherapy. Results: Results were showed significant (P<0.05) over expression of 8 genes (gelE(P=0.001). asa1(P=0.001), esp (P=0.002), aggA(P=0.001), efaA(P=0.002), enlA(P=0.001), cylA(P=0.003) and cylB(P=0.003) in patients after treatment compared to before treatment. Also significant over expression of these 8 genes has been detected in patients after treatment in compare with normal related subjects. No significant alterations were observed in expression of virulence genes between normal subjects and patients before treatment. Conclusions: it seems that immunotherapy may carry side effects such as increasing the pathogenicity risk of microflora in treated patients. These side effects could cause further infections after ending the immunotherapy of cancer. Based on these results, antibiotic treatments after immunotherapy for prevention of potential infections could be recommended.