Distribution of alpha 1(IV) and alpha 3(IV) chains of type IV collagen in lung tumours

Tumour invasion is associated with strong remodelling of the extracellular matrix, including the basement membrane (BM). The major structural component of BMs is type IV collagen, which is composed of an association of three a chains. In this study, the distribution of the alpha 1 and alpha 3 chains in both normal and neoplastic lung tissues has been examined by immunohistochemistry, using specific monoclonal antibodies. In normal tissues, the alpha 1(IV) chain was found in all BMs, whereas the alpha 3(IV) chain was only found in alveolar BMs. In 36 lung tumours, the alpha 1(IV) chain was detected in all cases, with irregular positivity around tumour clusters and in the stroma. It was noteworthy that this stromal distribution was particularly associated with the presence of cancer cells, whatever their invasive properties. In contrast, in 22 rumours out of 36, the alpha 3(IV) chain was only found at the interface between invasive tumour clusters and stroma, with a linear and disrupted pattern. These data show a distinctive distribution of type IV collagen chains in lung rumours, with expression of alpha 1(IV) chain and likely neosynthesis of the alpha 3(IV) chain around some invasive tumour clusters. The results suggest the involvement of these BM components in the process of tumour invasion. (C) 1997 by John Wiley & Sons, Ltd.