Effects of transforming growth factor β (TGF-β) receptor on lung carcinogenesis

Transforming growth factor beta (TGF-beta) type-II receptor mutations have been reported in several epithelial-type human malignancies. To elucidate the role of TGF-beta RII in lung cancer progression, we prepared gene-modified clones of the human lung cancer cell line NCI-H23. NCI-H23, a human non-small-cell lung adenocarcinoma cell line which has a frameshift mutation in, and reduced expression of, the TGF-beta type-II receptor (TGF-beta RII), exhibits resistance to growth inhibition by TGF-beta, in vitro. Transfection of NCI-H23 with a retroviral vector expressing wild-type TGF-beta RII restored the responsiveness of cells to exogenous TGF-beta, with reduced cell proliferation. Immunocytochemical analysis demonstrated nuclear translocation of Smad3 after TGF-beta(1) treatment in RII-restored NCI-H23 cells. Underphosphorylation of the retinoblastoma protein accompanying p21 up-regulation was observed after TGF-beta(1) treatment of NCI-H23-RII cells. Receptor restoration also changed the levels of VEGF mRNA induced by TGF-beta(1). However. impairment of TGF-beta signalling did not alter microvessel formation in vivo in transplanted tumours. Instead, in vivo tumorigenesis experiments revealed a remarkable difference in the number and sizes of the tumours derived from NCI-H23-RII cells and dominant negative NCI-H23-dnRII cells (P < 0.01). Collectively, these observations suggest that impairment of TGF-beta signal transduction contributes significantly to tumour progression, mainly by cell proliferation rather than by modulation of angiogenesis in human NCI-H23 lung carcinoma cells. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.