Prevention of hepatocarcinogenesis with phosphatidylcholine and menaquinone-4: In vitro and in vivo experiments

Background/Aims We examined whether phosphatidylcholine inhibited growth of hepatic cancer, as previously shown for menaquinone-4 (vitamin K2). Methods Growth inhibitions by phosphatidylcholine and/or menaquinone-4 and apoptosis induction by phosphatidylcholine were evaluated in vitro using human hepatic cancer cell lines (Hep-3B, Hep-G2, HuH-7, and Alexander). Effects of these agents were then investigated in male Sprague–Dawley rats against hepatocarcinogenesis induced by diethylnitrosamine plus phenobarbital. All rats were killed to examine livers to evaluate inhibitory potential macroscopically and immunohistochemically using an antibody against the marker of carcinogenesis, glutathione S-transferase and apoptotic induction by phosphatidylcholine using TUNEL staining. Blood samples were obtained by cardiac puncture. Results In vitro, phosphatidylcholine and menaquinone-4 each inhibited cancer cell growth and phosphatidylcholine induced apoptosis dose-dependently. Moreover, exposure to both synergistically inhibited growth in Hep-3B. In vivo, diets containing phosphatidylcholine with or without menaquinone-4 significantly reduced the number of macroscopic hepatic tumor nodules and the extent of abnormally immunoreactive foci conserving hepatic function on serum examinations compared with controls given only the carcinogens. Moreover, phosphatidylcholine supplementation induced apoptosis on TUNEL staining of liver sections. Conclusions Given together, phosphatidylcholine and menaquinone-4 may exhibit synergy against hepatocarcinogenesis conserving hepatic function that could benefit patients at high risk for hepatocellular carcinoma.