Involvement of apoptosis and autophagy in reducing mouse hepatoma ML-1 cell growth in inbred BALB/c mice by bacterial fermented soybean products

Abstract

Followed by the results of our previous in vitro report (Food Chem. Toxicol., 2007), the efficacy of the soybean fermentation products containing live bacteria (SCB) was demonstrated using a syngeneic animal model. Murine HBV-related hepatoma ML-1 cells, derived from inbred animals and tumorigenic in BALB/c mice, were implanted subcutaneously to the flank of BALB/c mice on day 0. Three days after implantation, SCB (1.0 or 1.3ml/mouse/day) or vehicle (water) was orally administrated daily until day 60. The results indicate that SCB significantly reduced (P<0.05) the volumes and weights of tumors during the experimental periods. Examination using TUNEL staining on section of tumors revealed apoptotic phenomenon of nuclear DNA double-strand breaks in the groups of mice received SCB. Immunohistochemistry further revealed an autophagic LC3-II punctate pattern. Of note, SCB induced autophagy in the absence or presence of apoptosis, whereas, apoptosis was observed only in combination with autophagy. In vitro study using autophagy inhibitor indicated that the induction of autophagy promoted apoptosis. These data imply that the suppression in tumor volumes and tumor weights by oral administration of SCB was due to the induction of apoptotic and autophagic cell death, which suggests therapeutic potential of SCB on HBV-related HCC.