ABSTRACT
BACKGROUND/AIMS: In human hepatocarcinogenesis the tumor precursor lesions and the sequence of genetic aberrations are not known. We therefore compared genetic alterations of different types of benign liver lesions to those of hepatocellular carcinoma. METHODS: By comparative genomic hybridisation (CGH) 40 cases, including cirrhotic liver (CL), focal nodular hyperplasia (FNHs), hepatocellular adenoma (HCAs), dysplastic nodules (DNs), primary hepatocellular carcinoma (HCCs), and hepatocellular metastases to the lung were studied. RESULTS: FNHs and HCAs exhibited few chromosomal abnormalities. Frequency and pattern of genetic alterations in DNs highly resembled those in HCCs: gains of DNA clustered in chromosome arms 1p/q, 7q, 15q, 16p, 17q, and 20q and losses were often found at 3p, 4q, 9p, and 11q. Aberrations on 1p, 6q, 8p/q, and 13q occurred almost exclusively in HCCs; the gain at 8q encompassed amplification of c-myc, as verified by fluorescence in situ hybridisation. CONCLUSIONS: The pattern of genetic alterations in HCCs resembled more the alterations found in DNs than in FNHs and HCAs, suggesting that DNs may be the actual tumor precursors. Furthermore, alterations at 4q, 9p, 11q, 16p, and 17q appear as early genetic events being crucial for hepatocarcinogenesis.
Subject(s)
Carcinoma, Hepatocellular/genetics , Chromosome Aberrations , Liver Neoplasms/genetics , Precancerous Conditions/genetics , Adenoma, Liver Cell/genetics , Adolescent , Adult , Aged , Base Sequence , Carcinoma, Hepatocellular/etiology , Chromosomes, Human/genetics , DNA, Neoplasm/genetics , Female , Genes, myc , Humans , Hyperplasia , In Situ Hybridization, Fluorescence , Liver/pathology , Liver Cirrhosis/genetics , Liver Neoplasms/etiology , Male , Middle AgedABSTRACT
Lung resistance-related protein (LRP) plays an important role in chemoresistance of tumor cells probably by altering nuclear-cytoplasmic transport processes. We analyzed the association between LRP expression and hepatocarcinogenesis in humans and rats by RT-PCR, immunoblotting, and immunohistochemistry. LRP was found in hepatocytes and bile epithelia of normal human and rat liver showing distinct interindividual variations. In human tissues, the LRP expression levels of dysplastic liver nodules, hepatocellular adenomas, and carcinomas were highly variable, including decreased but also distinctly increased staining intensities. Mean expression levels, however, were comparable to the surrounding tissue. Considerable levels of LRP mRNA and protein were also found in human hepatoma cell lines. To study LRP expression from the beginning of hepatocarcinogenesis onward, rats were subjected to a tumor initiation/promotion protocol leading to preneoplastic hepatocytes present as single cells or multicellular clones, followed by adenoma and carcinoma. All of the (pre)neoplastic rat liver lesions expressed, comparable to the surrounding tissue, considerable amounts of LRP. We conclude that LRP might be one mechanism involved in the intrinsically high but variable chemoresistance of normal and (pre)neoplastic hepatocytes.
