MODULATION OF COLLAGEN SYNTHESIS IN LUNG FIBROBLASTS

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Bleomycin is a glycopeptide which is used to treat various carcinomas. One of the toxicities of bleomycin therapy is lung fibrosis which is the major and limiting toxicity of this antineoplastic drug. The purpose of the proposed studies is to determine the mechanism(s) of bleomycin induced increased collagen synthesis and collagen deposition in lung. This proposal encompasses the role of transforming growth factor beta (TGF-beta) and interleukin-1 (IL-1) in mediating the bleomycin-induced response of lung to increased type I procollagen mRNAs and type I procollagen synthesis. These collagen parameters are both increased by bleomycin, TGF-beta and IL-1. Bleomycin-treated rat lung fibroblasts will be assayed for type I procollagen synthesis and amount, type I procollagen mRNA transcription, IL-1 mRNAs and TGF-beta MRNA, growth factor mRNA synthesis and degradation. We have already demonstrated that TGF-beta mRNA and TGF-beta MRNA synthesis are increased in rat lung fibroblasts treated with bleomycin. To assess the in vivo situation we will determine type I procollagen synthesis and amount, type I procollagen MRNA transcription, the cellular amounts of TGF-beta mRNA, IL-1 mRNAs and the synthesis and degradation of these growth factor mRNAs in fibroblasts isolated from lung of control and bleomycin-treated rats. We will determine the direct effects of TGF-beta and IL-1 on type I procollagen synthesis and amount, the cellular levels of type I procollagen mRNAs, MRNA synthesis and degradation. We will use DNA deletion constructs to determine the specific DNA sequence(s) in the 5'flanking region of the type I procollagen gene which possibly are required for bleomycin, TGF-beta and IL-1 regulation of procollagen gene expression. The proposed studies will define a molecular basis for bleomycin-induced lung fibrosis and possibly a mechanism for other fibrogenic agents of lung. These studies will also establish an interrelationship between bleomycin-induced lung fibrosis, increased collagen synthesis and the growth factors, IL-1 and TGF-4.