Chromosomal allelic imbalance evolving from liver cirrhosis to hepatocellular carcinoma

Abstract

Background & Aims: Cirrhotic nodules have long been assumed to be the precancerous lesions of hepatocellular carcinoma (HCC). We thus investigated the allelic imbalance (Al) in cirrhotic nodules to define the genetic aberrations in early hepatocarcinogenesis. Methods: One hundred eighty cirrhotic nodules from 7 female patients with HCC were collected by microdissection. Their clonality nature was assessed by examining the X chromosome methylation pattern. Al in monoclonal cirrhotic nodules and the corresponding HCCs were analyzed with microsatellite polymorphic markers. Results: One hundred one out of 180 nodules (56.1%) were monoclonal and the average fractional Al (FAI) was 21%, lower than the 40% in HCC. Their overall Al patterns differed significantly from that in HCC (P < 0.001) with FAI on 2q, 4q, 8p, and Xq higher than the mean value. Comparison of FAI in nodules (stratified by increasing total Al events) further revealed a progressive increase of FAI on 4q, 8p, and Xq. In contrast, FAI on 1p, 13q, 16q, and 17p were low in nodules but rose above the mean only in HCC. Conclusions: About half of the cirrhotic nodules are monoclonal and already have chromosome aberrations. Al on 4q, 8p, and Xq may be the earlier mutations, whereas Al on 1p, 13q, 16q, and 17p occurs late in hepatocarcinogenesis.