Loss of heterozygosity of the retinoblastoma gene in liver cirrhosis accompanying hepatocellular carcinoma

Carcinogenesis is a multistep process. Most hepatocellular carcinoma (HCC) is preceded by liver cirrhosis, but the genetic changes involved in cirrhosis are not known well. The present study was conducted to evaluate aberration of the retinoblastoma (RB) gene in HCC and adjacent non-tumorous liver using 22 patients with chronic liver damage accompanying HCC. The specimens obtained by microdissection from paraffinembedded tissues were analyzed using an assay based on the polymerase chain reaction for highly polymorphic nucleotide sequences of microsatellites in theRB gene. Out of 22 cases, 15 showed constitutional heterozygosity for the microsatellite markers. In 11 (73.3%) of these 15 informative cases, the primary HCC foci showed loss of heterozygosity (LOH). In 8 of these 11 doubly informative (informative and LOH-positive in primary HCC) cases, LOH was found in 20 (64.5%) of 31 microdissected non-tumorous foci. All of the non-tumorous foci showingRB loss were cirrhotic lesions but there were no foci of chronic hepatitis. The remaining 4 cases without LOH in HCC foci showed no LOH in non-tumorous lesions. In our study, LOH of theRB gene was frequently observed in liver cirrhosis surrounding tumor.Abbreviations RB retinoblastoma - HCC hepatocellular carcinoma - LOH loss of heterozygosity - PCR polymerase chain reaction - (CA)_n cytosine-adenine - (AT)_n adenine-thymine - n number of repeats