Nuclear matrix of calreticulin in hepatocellular carcinoma

Nuclear matrix protein profiles of malignant cells vary from their normal c ounterparts. By two-dimensional gel electrophoresis, we analyzed nuclear ma trix proteins in 11 hepatocellular carcinomas and compared them with corres ponding non-neoplastic liver tissue, Although the compositions were mostly similar, several peptides were noted predominantly in the former, The most prominent one was an acidic protein of apparent M-r 62,000, which was ident ified to be calreticulin upon NH2-terminal amino acid sequencing, By immuno blotting, calreticulin was confirmed to be present abundantly in the nuclea r matrix fraction of carcinomas but not in that of the nonmalignant liver t issue. Interestingly, the total content of calreticulin was similar between them. By immunofluorescence microscopy, evident nuclear immunostaining was detected in carcinomas. Cal-reticulin was also found to be in the nuclear matrices of various carcinoma cell lines. We conclude that calreticulin Is a component of the nuclear matrix. The formation and/or expansion of the ca lreticulin-nuclear matrix may be related to the activated cell growth.