[Lani]

Int J Cancer. 2009 Oct 28. [Epub ahead of print]
The anti-cancer effect of probiotic Bacillus polyfermenticus on human colon cancer cells is mediated through ErbB2 and ErbB3 inhibition.
Ma EL, Choi YJ, Choi J, Pothoulakis C, Rhee SH, Im E.

Inflammatory Bowel Disease Center, Division of Digestive Diseases, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA.
A wealth of data implicates that ErbB receptors have essential roles in tumor development. Probiotic bacteria are known to exert an anti-cancer activity in animal studies. Bacillus polyfermenticus (B.P.), a probiotic bacterium, has been clinically used for a variety of gastrointestinal disorders in East Asia. Here we investigated the effect of B.P. on the growth of tumors and its putative mechanism of actions. Conditioned medium of B.P. cultures (B.P. CM) inhibited the growth of human colon cancer cells including HT-29, DLD-1 and Caco-2 cells. Moreover, B.P. CM suppressed colony formation of HT-29 cells cultured on soft agar and reduced carcinogen-induced colony formation of normal colonocytes. Furthermore, data from the mouse xenograft model of human colon cancer cells showed reduced tumor size in B.P. CM-injected mice when compared to E.coli conditioned medium-injected mice. Exposure of B.P. CM to HT-29 cells for 24 h, 48 h and 2 weeks reduced ErbB2 and ErbB3 protein expression as well as mRNA levels. Moreover, cyclin D1 expression which is required for ErbB-dependent cell transformation was decreased by B.P. CM. Furthermore, transcription factor E2F-1 which regulates cyclin D1 expression was also decreased by B.P. CM. These results show that B.P. inhibits tumor growth and its anti-cancer activity occurs, at least in part, through suppressing ErbB2 and ErbB3. Taken together, our study suggests that this probiotic may be clinically used as a prophylactic treatment to prevent colon cancer development. (c) 2009 UICC.

PMID: 19876926