Prophylactic effects of secretion metabolites of dairy lactobacilli through downregulation of ErbB-2 and ErbB-3 genes on colon cancer cells
Colon cancer is one of the most prevalent cancers, and intestinal microbial community plays a pivotal role in colorectal tumor genesis. Probiotics as live microorganisms may be able to exert an anticancer effect in colon cancer. The aim of this study was to isolate and identify Lactobacillus spp. from traditional dairy products with probiotic properties and to investigate their anticancer effects through ErbB-2 and ErbB-3 gene expression in colon cancer cells. The isolated lactobacilli from yogurt and cheese samples were molecularly identified by blasting of 16–23s rDNA region PCR sequenced products. The probiotic properties, including acid and bile tolerance, antimicrobial activity, and antibiotic susceptibility, were assayed. The proliferation inhibition effects of lactobacilli secretion metabolites with probiotic potential on colon cancer cell lines (HT-29 and caco-2) were analyzed using MTT assay. The real-time PCR was used for assessment of ErbB-2 and ErbB-3 gene expression after being treated with probiotics. Four species of bacteria with the most probiotic properties, including Lactobacillus casei, Lactobacillus paracasei, Lactobacillus rhamnosus, and Lactobacillus plantarum, were characterized and their effects on different human cell lines were taken into consideration. Total bacterial secretions significantly reduced the viability of HT-29 and caco-2 cancer cells compared with untreated controls. The metabolites secreted by bacteria downregulated the expression of ErbB-2 and ErbB-3 genes in colon cancer cells. The present study indicated that probiotic bacteria isolated from traditional dairy products exert anticancer effect on colon cancer cells through the downregulation of ErbB-2 and ErbB-3 gene expression.