EXPRESSION OF ALPHA(3)BETA(1) INTEGRIN RECEPTOR AND ITS LIGANDS IN HUMAN LUNG-TUMORS

Increasing experimental evidence demonstrates that malignant transform ation is associated with changes in the repertoire of expression of th e integrin family of molecules, which mediate cell-matrix and cell-cel l interactions. We have analyzed immunohistochemically and immunochemi cally the expression of VLA-3 integrin and its known ligands, namely, laminin (LM), fibronectin (FN), collagen type IV (Cell IV), nicein (NI C), and entactin/nidogen (ENT), in lung tumors of various histological types. alpha(3) beta(1) was detectable in normal bronchial epithelium and along basement membranes of alveolar walls. In non-small cell lun g carcinomas (NSCLC) the integrin was expressed in 82% of the cases, i ndependently of histological type and degree of differentiation of the tumors. On the other hand, only 13% of the small cell lung carcinomas (SCLC) displayed a weak and heterogeneous distribution of the alpha(3 ) beta(1) complex. Our findings were confirmed immunochemically using long-term tumor cell lines. While the expression of both alpha(3) beta (1) and ligands LM, FN, Coll IV, and Ent correlated in NSCLC with the presence of basement membranes, FN was the only ligand detectable in t he stroma of SCLCs. A selective loss of nicein in basement membranes w as demonstrated in NSCLC indicating an impairment of expression of thi s glycoprotein following malignant transformation. (C) 1995 Wiley-Liss , Inc.