Diagnostic significance of alanine aminotransferase isoenzymes in alcoholic and non-alcoholic fatty liver cancers

Objectives: Alanine aminotransferase (ALT) expression is highly elevated in the serum of patients with hepatocellular carcinoma. However, the role of ALT isoenzymes in the total ALT activity remains unclear. In the present study, we systematically investigated the role of ALT isoenzymes in alcoholic and non-alcoholic fatty liver cancer. Materials and methods: The expression of ALT1 and ALT2 at the mRNA and protein levels in 25 paired primary liver cancer tissues was detected by reverse transcription quantitative PCR (RT-qPCR), West-ern blotting, and immunohistochemistry. Serum ALT activity was determined using an au-tomated biochemical analyzer. Results: The mRNA and protein expression levels of ALT1 and ALT2 were lower in the tissues of alcoholic and non-alcoholic fatty liver cancers than in the paracancerous tissues. Notably, ALT2 was highly expressed in non-alcoholic fatty liver cancer tissues compared with alcoholic fatty liver cancer tissues. Total serum ALT activity was mainly contributed by ALT1 in alcoholic fatty liver cancer, whereas ALT1 contributed only marginally more to the total ALT activity than ALT2 in non-alcoholic fatty liver can-cer. ALT2/ALT1 ratio can well discriminate normal control group, alcoholic liver cancer and non-alcoholic liver cancer. Conclusion: ALT1 contributed more to the total ALT activity than ALT2 in both alcoholic and non-alcoholic fatty liver cancer. Serum ALT2 to ALT activity was higher in non-alcoholic fatty liver cancer than that in alcoholic fatty liver cancer. ALT2/ALT1 ratio has some diagnostic significance for alcoholic and non-alcoholic liver cancer.