Targeted inhibition of the extracellular signal-regulated kinase kinase pathway with AZD6244 (ARRY-142886) in the treatment of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a common malignancy in Asia and Africa. We previously reported that overexpression of extracellular signal-regulated kinase (ERK) kinase 1/2 (MEK1/2) and ERK1/2 was detected in HCC, and that their activation was required for liver cancer cell proliferation and survival. In the present study, we determined the efficacy of a specific MEK1/2 inhibitor AZD6244 (ARRAY-142886) in treatment of HCC. Treatment of primary HCC cells with AZD6244 led to growth inhibition, elevation of the cleavage of caspase-3 and caspase-7, and cleaved poly(ADP)ribose polymerase, but inhibition of ERK1/2 and p90RSK phosphorylation. Studying the protein expression profile of seven HCC xenografts revealed that their growth rate was positively correlated with the levels of phosphorylated MEK. AZD6244, when given p.o. to mice bearing these xenografts, resulted in a dose-dependent inhibition of tumor growth. AZD6244-induced growth suppression was associated with inactivation of ERK1/2 and p90RSK, and up-regulation of activated caspase-3 and caspase-7, and cleaved poly(ADP)ribose polymerase. Our data suggest that the MEK-ERK pathway plays an important role in the growth and survival of liver cancer cells and that the HCC xenograft models are excellent tools for screening preclinical drugs. Targeted inhibition of the MEK-ERK pathway with AZD6244 may represent an alternative approach for the treatment of this disease.