Immunohistopathological characterizatin of spontaneous metastases in a human lung mucoepidermoid adenocarcinoma (HLMC) xenograft.

The most common clinical form of lung cancer is a disseminated disease with distant metastases; several years of cancer progression precede presentation, and this ultimately limits the efficacy of curative therapy. In this immunohistochemical study, we examined a mucinous adenocarcinoma cell line, maintained by xenogeneic transplantation, and a spontaneous metastatic variant which produces distant tumors (in liver, spleen and kidney). The aim was to investigate possible parameters which characterize the metastatic process. Histopathological comparison between the two subcutaneous transplanted tumor lines showed that both lines presented a similar cellular morphology, a different pattern of cellular growth and an increased vascularization in the metastatic line with respect to its parent. All the tumor sections expressed differential immune reactivity with monoclonal antibodies against Lewis y (MAb C14), sialyl-Lewis x (MAb SNH3) and Lewis x (MAb FH2) determinants. Neither expressed MUC 1 mucins detectable with monoclonal antibodies reactive with the mucin protein core (MAbs C595 and SM3) nor was carcinoembryonic antigen (MAb C365) expressed. Neoplastic cells were reactive with an anti-pan cytokeratin monoclonal antibody confirming their epithelial histogenesis. Our findings have been evaluated with respect to defining metastatic phenotypes in lung cancer by examination of distinct histopathological and immunological parameters.