Chemically induced mouse liver tumors are resistant to treatment with atorvastatin.

backgroundAtorvastatin is a potent inhibitor of the mevalonate pathway and widely used as a hypolipidemic drug. Some epidemiological studies and animal experiments indicate that the long-term use of atorvastatin and structurally related drugs might be associated with a reduced risk of developing hepatocellular carcinoma (HCC), the most common hepatocellular malignancy in humans. However, the potential of atorvastatin to inhibit HCC formation is controversially discussed.

methodsHepatocellular tumors were chemically induced by treatment of C3H/He mice with 10 μg/g body weight N-nitrosodiethylamine and the ability of atorvastatin to interfere with tumor formation was investigated by treatment of mice with 0.1% atorvastatin in the diet for 6 months. Tumor size and tumor multiplicity were analyzed, as were tissue levels of cholesterol and atorvastatin.

resultsAtorvastatin treatment efficiently reduced serum cholesterol levels. However, the growth of tumors driven by activated MAPK (mitogen-activated protein kinase) signaling was not attenuated by the presence of the drug, as evidenced by a lack of reduction of tumor volume or tumor multiplicity by atorvastatin. Levels of the atorvastatin uptake transporters Oatp1a4 and Oatp1b2 were down-regulated at the mRNA and protein levels in chemically induced mouse liver tumors, but without striking effects on atorvastatin concentrations in the tumor tissue.

conclusionIn summary, the present data provide substantial evidence that atorvastatin does not beneficially influence tumor growth in mouse liver and thereby challenge the hypothesis that statin use might protect against hepatocellular cancer.