Statin attenuates cell proliferative ability via TAZ (WWTR1) in hepatocellular carcinoma

Diabetes and obesity are associated with non-alcoholic steatohepatitis and an increased incidence of hepatocellular carcinoma (HCC). TAZ and YAP are equivalently placed downstream effectors of the Hippo pathway with oncogenic roles in human cancers. Statins are commonly used to patients with metabolic problems as hypercholesterolemia. Statins also have anti-cancer properties, and the cross-talk between mevalonate pathway and Hippo pathway was known. The aim of this study is to confirm the statin's anti-cancer effects on HCC cells and its survival benefits in HCC patients with curative surgery. TAZ expression level in HCC cell lines was analyzed by western blot. Two cell lines (HLF and HuH1) were used in this study. Then the mechanism of statin's anti-proliferative effect was examined in HLF and HuH1 cells. In clinical setting, overall survival and recurrence-free survival (RFS) rate were examined in comparison between statin intake and statin non-intake group. The proliferation assay using four different statins (atorvastatin, pravastatin, fluvastatin, simvastatin). Simvastatin and fluvastatin showed very strong growth suppressive effects, and induced apoptosis in HLF cells, but not HuH1 cells. TAZ expression was suppressed in HLF cells by fluvastatin and simvastatin treatment. The similar change pattern was confirmed in p-ERK1/2 and ERK. In HuH1 cells, such expression change was not confirmed. In clinical setting, statin intake was significantly associated with longer RFS in the HCC patients with hepatectomy (P = 0.038). The statin had the anti-proliferative effects and induced apoptosis in HCC cells and improved the prognosis of HCC patients.

Prevention of hepatocellular carcinoma by correction of metabolic abnormalities: Role of statins and metformin

Hepatocellular carcinoma is the third leading cause of cancer-related deaths in the world. It is associated with an important mortality rate and the incidence is increasing. Patients showing metabolic syndrome seem to have higher incidence and mortality rates from hepatocellular carcinoma than healthy subjects, especially those with type 2 diabetes mellitus and obesity. Thus, metformin and statins, both to treat features of metabolic syndrome, have been proposed to decrease the risk of hepatocellular carcinoma. Otherwise, liver cancer is the result of a complex process which impairs several signaling cascades, such as RAS/RAF/mitogen-activated protein kinase kinase (MEK)/extracellular-signal-regulated kinase (ERK), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) and Wnt/β-catenin signaling. Metformin (through 5′-adenosine monophosphate-activated protein kinase pathway activation) and statins (through 3-hydroxy-3-methylglutaryl coenzyme A inhibition) show anti-tumoral properties modifying several steps of RAS/RAF/MEK/ERK, PI3K/AKT/mTOR and Wnt/β-catenin signaling cascades. On the other hand, metformin and statins have been found to reduce the risk of hepatocellular carcinoma up to 50% and 60%, respectively. Furthermore, both drugs have shown a dose-dependent protective effect. However, information about chemopreventive role of metformin and statins is mainly obtained of observational studies, which could not take into account some bias. In conclusion, given the rising of incidence of hepatocellular carcinoma and the important morbidity and mortality rates associated with this cancer, looking for chemopreventive strategies is an essential task. Randomized controlled trials are needed to determine the definite role of metformin and statins on the prevention of hepatocellular carcinoma.

Chemically induced mouse liver tumors are resistant to treatment with atorvastatin

Background

Atorvastatin 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.

Methods

Hepatocellular 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.

Results

Atorvastatin 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.

Conclusion

In 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.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-766) contains supplementary material, which is available to authorized users.