Evaluation of the role of extracellular matrix proteins, polyunsaturated fatty acids and c-myc expression in the inhibition of the serum-free growth of epithelial cells by TGF-beta 1.
Novel or modified serum-free media were developed for the anchorage-dependent growth of nontransformed murine mammary epithelial cells (MMEC) and Balb/MK murine keratinocytes respectively. Growth rates for both cell lines were similar in serum-containing and serum-free media. The serum-free media were used to evaluate potential mechanisms of epithelial cell growth regulation by type 1 transforming growth factor beta (TGF-beta 1). The growth of MMEC and Balb/MK cells was reversibly inhibited 40-65% in a time- and dose-dependent fashion by TGF-beta 1 under both serum-containing and serum-free conditions. Constitutive over-expression of a transfected c-myc oncogene in MMEC did not result in loss of sensitivity to growth inhibition by TGF-beta 1. In addition, Balb/MK and MMEC growth inhibition by TGF-beta 1 was not potentiated by polyunsaturated fatty acids or reversed by vitamin E. Exogenous type V collagen was able to mimic the inhibitory effects of TGF-beta 1 on the serum-free growth of Balb/MK and MMEC. In contrast, collagen types I and IV, fibronectin and laminin did not inhibit the growth of these cells. The type V collagen used was not contaminated with TGF-beta, and subsaturating, but not saturating concentrations of type V collagen and TGF-beta 1 were additive with respect to Balb/MK and MMEC growth inhibition. These results demonstrate that nontransformed epithelial cell growth inhibition by TGF-beta 1 is mediated by mechanisms distinct from those observed with certain carcinoma and melanoma cells. Our results also suggest the possible involvement of type V collagen in Balb/MK and MMEC growth inhibition by TGF-beta 1.
Sarubbi
D J
DJ
Roche Institute of Molecular Biology, Roche Research Center, Nutley, New Jersey 07110.
Narayanan
R
R
Telang
N T
NT
Newman
M J
MJ
D000818:Animals; D001769:Blood; D002455:Cell Division / Q000187:drug effects; D003094:Collagen / Q000494:pharmacology; D004848:Epithelium / Q000473:pathology; D016326:Extracellular Matrix Proteins / Q000494:pharmacology*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D015603:Keratinocytes / Q000166:cytology; D008321:Mammary Glands, Animal / Q000473:pathology*; D008325:Mammary Neoplasms, Experimental / Q000473:pathology*; D051379:Mice; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D016326:Extracellular Matrix Proteins; D005231:Fatty Acids, Unsaturated; D016271:Proto-Oncogene Proteins c-myc; D016212:Transforming Growth Factor beta; D003094:Collagen