Extracellular matrix in preneoplastic lesions and early cancer of the lung.

Characterization of preneoplastic lesions mainly concentrated on cellular, nuclear and epithelial atypias. The extracellular matrix was almost neglected, although malignant tumour cells interact with extracellular matrix molecules during tumour invasion. Until now systematic investigations of extracellular matrix components in preneoplastic lesions and early stages of lung cancer are lacking. 150 preneoplastic lesions, 10 specimens of early cancer and 30 specimens of normal bronchial mucosa were examined by means of immunofluorescence microscopy. The distribution of collagen type I and III and the non-collagenous glycoproteins laminin and fibronectin have been investigated by an indirect immunohistochemical method. With an increasing degree of preneoplasia an increased matrix disarrangement of the basement membrane zone could be observed. In severe dysplasia and carcinoma in situ neosynthesis of collagen type III and especially laminin in close association to neoangiogenesis could be demonstrated besides a disintegration of extracellular matrix components. In early lung cancer numerous laminin positive basement membrane like structures are situated around tumour cells. An enhanced deposition of collagen type I and III fibres could be demonstrated around tumour cell islets. The results indicate a partial loss of function in preneoplastic basal cells in cases of dysplasia and carcinoma in situ. In early stages of invasive squamous cell carcinoma of the bronchus, extracellular matrix components obviously could be produced by tumour cells.