Telomerase activation in human hepatocarcinogenesis

Active telomerase is present in the majority of malignant human tumors, including most cases of hepatocellular carcinoma (HCC). Telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase, has been found to be expressed in HCCs, dysplastic (precancerous) nodules (DNs), and regenerative nodules arising in cirrhosis. In a study reported in this issue of the journal, hTERT mRNA levels were assessed by quantitative real-time RT-PCR in various nodular lesions dissected from liver specimens of patients with chronic hepatitis B. High levels of hTERT mRNA were present in HCCs, high-grade DNs, and occasional low-grade DNs, whereas low levels were found in normal livers, livers with chronic hepatitis B (with or without cirrhosis), large regenerative nodules, and most low-grade DNs. Therefore, quantitative assessment of hTERT mRNA may provide a useful adjunct to histopathologic evaluation of large hepatic nodules. Indeed, emerging data from gene expression analyses of DNs and HCCs suggest that hTERT can be included in sets of select genes that provide "molecular signatures" with utility in the diagnosis and management of nodular hepatic lesions. Most importantly, tackling the mechanisms of telomerase activation may provide new means of therapy for HCC and other cancers.