Expression of a glypican-related 62-kDa antigen is decreased in hepatocellular carcinoma in correspondence to the grade of tumor differentiation

A monoclonal mouse antibody, Be-F4, was generated by means of immunization with a synthetic oligopeptide. In Western blots, this antibody recognizes a n antigen with an apparent molecular mass of 62 kDa. termed p62. Immunohist ochemical analysis of p62 in hepatocellular carcinoma (HCC) specimens (n = 33) and in corresponding non-cancerous liver tissue was performed using mon oclonal antibody Be-F4. All non-neoplastic hepatic cells showed, without ex ception, a moderate or strong staining intensity of the 62-kDa antigen, rec ognized by Be-F4. In contrast to the non-neoplastic hepatocytes, the cellul ar p62 content was unambiguously reduced in all malignant cells. The extent of decrease of p62 corresponded to the grade of histological differentiati on of HCC cells (P < 0.001). Using a semiquantitative scoring system, the m edian of p62 expression, which was 2.1 for normal hepatocytes, was signific antly reduced to 1.2 for G1, 1.0 for G2, and 0.2 for G3 HCCs. These data su ggest that neoplastic transformation is associated with a reduced p62 conte nt.