CLONALITY OF LARGE REGENERATIVE NODULES IN LIVER-CIRRHOSIS

The role of the large regenerative nodule (RN) in hepatocarcinogenesis is not clear, although the incidence of hepatocellular carcinoma (HCC ) is high in cirrhotic liver. This study was aimed at clarifying the p reneoplastic nature of large RN without atypia. We analyzed the clonal ity of HCCs and large RNs, ranging in size from 0.6 to 1.2 cm, of cirr hotic liver by X-linked human androgen receptor (HUMARA) gene assay, u sing the principle of random X chromosome methylation and inactivation in females. Eleven cases of HCC and five cases of large RN without at ypia from ten female patients were selected. All HCCs, large RNs and p aired non-tumorous tissue from adjacent liver were selectively microdi ssected from deparaffinized hematoxylin and eosin stained slides. Geno mic DNA was isolated and digested with Hha I. Polymerase chain reactio n (PCR) amplification of the HUMARA gene was performed using a PCR mix ture containing [alpha-P-32]-dCTP. The PCR products were separated by gel electrophoresis and analysed by autoradiography. HUMARA was inform ative in nine out of ten female patients. In the informative 10 HCCs f rom nine patients, 9 HCCs were monoclonal and one case was polyclonal. The HCC case that showed polyclonality contained many inflammatory ce lls in the tumor. All of the large RNs were polyclonal. No allelic los s of chromosome 18q was present in the large RNs in constrast to the 3 out of 7 HCCs, which showed allelic deletion in chromosome 18q. We co nclude that all or most of the cells composing the large RNs without a typia are polyclonal and the size of a nodule may not be important in hepatocarcinogenesis. This clonality assay may be informative for the differentiation between regenerative and preneoplastic nodules in cirr hotic liver.