Anti-cancer Activities Of Lactobacillus Helveticus NS8 And Underlying Mechanism

Colorectal cancer(CRC)is the third common malignant tumor in the world with high incidence and mortality.The anti-tumor activities of probiotics have been indicated by increasing evidences.However,strain-specificity has been widely considered.So it is necessary to find specific probiotic strains with definite anti-tumor attributes and mechanisms.In this study,the anti-tumor effects of Lactobacillus helveticus NS8 and underlying mechanisms were investigated.Firstly,we found that the viabilities of several cell strains of human colon carcinoma(HT29,Caco2 and SW480)were decreased when co-cultured with NS8,which indicated good anti-proliferative effect of NS8.In addition,NS8 induced the apoptosis of colorectal cancer cell as revealed by annexinV/DAPI double staining and TUNEL staining,and increased the activation of cellular Caspase-3.Then the Babl/c mice model with subcutaneous tumor homografts grown from implanted CT-26 colon cells was used in our in vivo experiments.Orally pre-administrated with NS8 for 14 days significantly inhibited the growth of tumors,by causing approximately 40% decrease in tumor weights and volumes,and also induced cell apoptosis in tumor tissues.Futhermore,the gene expressions of cyclooxygenase(Cox)-2 and angiogenine(Ang)in tumor tissues from mice treated with NS8 were significantly down-regulated,whereas the expression of interferon(IFN)-? was partly increased.The anti-tumor effect of NS8 may be relevant to the NS8-driven activation of corresponding anti-tumor immunity.Taken together,our findings provide confirmed evidence of anti-tumor properties of NS8 and support the application development of functional and therapeutic probiotics.