Expression of the laminin gamma 2 chain in different histological types oflung carcinoma. A study by immunohistochemistry and in situ hybridization

Sixty-four malignant lung tumours and 12 of their regional lymph node metas tases were analysed for expression of the laminin gamma 2 chain by immunohi stochemistry and in situ hybridization. Expression of the laminin gamma 2 c hain was strongest in squamous cell carcinomas, followed by adenocarcinomas and large cell carcinomas. Positive cells, except for large cell carcinoma s, were located at the epithelial-stromal interface of tumour clusters. An important exception was small cell lung carcinoma, with only a low level of laminin gamma 2 chain expression. Apart from tumour type, this may reflect the relatively scanty fibrous stroma in these tumours and supports previou s observations that small cell lung carcinoma cells, contrary to other type s, lack surface expression of alpha(6)beta(4) integrin, the specific lamini n-5 binding receptor. In frozen sections, immunohistochemistry showed linea r basement membranes around tumour clusters in squamous cell carcinomas and adenocarcinomas. This shows that carcinoma cells are capable of heavy depo sition of the laminin gamma 2 chain around tumour clusters and suggests tha t a laminin gamma 2 chain-containing substrate may be of significance for t he spread and growth of malignant tumours. Copyright (C) 1999 Jolm Wiley & Sons, Ltd.