Laminin gamma 2 chain is an extracellular matrix protein that plays an important role in cell migration and tumor invasion. We report altered expression and characteristic localization of this chain in a series of 105 cases of intrahepatic cholangiocarcinomas examined immunohistochemically. All tumors were grossly classified into the following three types: intraductal growth type (n=9), periductal infiltrating type (n=8) and mass-forming type (n=88). The tumors exhibited three distinct staining types: basement membrane staining, cytoplasmic staining and stromal staining. The basement membranous staining of laminin gamma 2 chain was more frequent in biliary dysplasia, intraductal growth and periductal infiltrating type than in mass-forming type. The cytoplasmic staining of carcinoma cells was observed especially at the cancer-stromal interface or at the invasive front of tumors. Stromal staining of laminin gamma 2 chain was essentially localized in the stroma around cancer cells at the invasive area, and the expression was significantly correlated with tumor aggressive factors and a poor prognosis in patients with intrahepatic cholangiocarcinoma. We conclude that laminin gamma 2 chain exhibits aberrant expression in a stepwise manner through different aggressive stages of tumor progression.
