Telomerase activity in precancerous hepatic nodules

BACKGROUND: Recent studies have demonstrated that telomerase, a reverse transcriptase linked to cellular "immortalization," is activated in a variety of malignant human tumors. This study was conducted to determine whether telomerase activity represents a marker of malignant transformation in precancerous (dysplastic) nodules arising in patients with cirrhosis. METHODS: Telomerase activity was evaluated in frozen tissue samples of 14 cirrhotic liver specimens and 30 large nodular lesions contained therein, including 13 large regenerative nodules/low grade dysplastic nodules, 10 high grade dysplastic nodules, and 7 hepatocellular carcinomas (HCCs). A modified telomeric repeat amplification protocol was used. RESULTS: There was a clear-cut difference in telomerase activity levels between HCC (positive or strongly positive) and cirrhotic liver samples (weakly positive or negative). The majority of large noncancerous nodules (86%) exhibited telomerase activity levels similar to HCCs. However, such activity was not limited to dysplastic lesions but also was detected in some large regenerative nodules. CONCLUSIONS: These findings suggest that telomerase activation is an early event in large nodule formation in cirrhosis, which may facilitate the action of other factors in the process of carcinogenesis. Telomerase activity in large hepatic nodules is not always indicative of malignant transformation.