DISTRIBUTION OF ALPHA-1(IV) AND ALPHA-3(IV) CHAINS OF TYPE-IV COLLAGEN IN LUNG-TUMORS

Tumour invasion is associated with strong remodelling of the extracell ular matrix, including the basement membrane (BM). The major structura l component of BMs is type IV collagen, which is composed of an associ ation 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 be en examined by immunohistochemistry, using specific monoclonal antibod ies. In normal tissues, the alpha 1(IV) chain was found in all BMs, wh ereas 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 irregu lar positivity around tumour clusters and in the stroma. It was notewo rthy that this stromal distribution was particularly associated with t he presence of cancer cells, whatever their invasive properties. In co ntrast, 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 l inear and disrupted pattern. These data show a distinctive distributio n 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 s ome invasive tumour clusters. The results suggest the involvement of t hese BM components in the process of tumour invasion. (C) 1997 by John Wiley & Sons, Ltd.