The expression of nuclear lamins in human liver: an immunohistochemical study.

The nuclear lamina is a meshwork of intermediate filaments adjacent to the inner nuclear membrane that in mammalian cells is predominantly composed of three proteins: lamin A, lamin B, and lamin C. Because lamin A and C (A-type lamins) expression has been shown to be lacking in several types of undifferentiated or rapidly proliferating cells, we investigated lamin expression in the human liver in conditions with hepatocellular regeneration (cirrhosis of various etiologies and macroregenerative nodules) and in hepatocellular carcinomas of various grades of differentiation. Immunohistochemical stains for A-type lamins and lamin B were performed on frozen tissue sections with the avidin-biotin complex method. Normal and regenerating hepatocytes, biliary epithelial cells (ductal and ductular cells), and hepatocellular carcinoma cells invariably expressed both A-type lamins and lamin B. These findings indicate that in hepatocellular regeneration and malignant transformation the production of both A-type lamins and lamin B is preserved.