Ehrlich ascites tumor cells produce a transforming growth factor-beta (TGFbeta)-like activity but lack receptors with TGFbeta-binding capacity.
Ehrlich ascites tumor cells incorporate [methyl-3H]thymidine into DNA independently of exogenous growth factors or fetal calf serum. Using an acid/ethanol extraction procedure we have obtained from these tumor cells a fraction that induces both the proliferation and the formation of cell foci by Swiss 3T3 mouse fibroblasts in the presence of insulin; inhibits the proliferation of Mv1Lu mink lung epithelial cells; and stimulates the growth of NRK rat kidney fibroblasts in soft-agar in the presence of epidermal growth factor. An antibody against transforming growth factor-beta (TGFbeta) prevents both the tumor extract-induced proliferation of Swiss 3T3 fibroblasts and the tumor extract-induced proliferative arrest of Mv1Lu cells. The tumor cells secrete a TGF beta-like activity to the extracellular medium in a partially-activated form. However, authentic TGFbeta does not affect their proliferation, and no TGFbeta receptors were detected using [125I]TGFbeta as a ligand. Therefore, the absence of TGFbeta receptors with ligand-binding capacity in these tumor cells may bypass the negative control that this factor exerts on the proliferation of their normal cell counterparts.
Elexpuru
A
A
Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
Martín-Nieto
J
J
Jimenez
A
A
Gómez
C
C
Villalobo
A
A
D016475:3T3 Cells; D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000503:physiopathology*; D002448:Cell Adhesion / Q000187:drug effects; D002455:Cell Division; D002460:Cell Line; D017077:Culture Media, Conditioned; D004247:DNA / Q000096:biosynthesis; D004815:Epidermal Growth Factor / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D008168:Lung; D051379:Mice; D008907:Mink; D051381:Rats; D018125:Receptors, Transforming Growth Factor beta / Q000032:analysis*; D014020:Tissue Extracts / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000096:biosynthesis* / Q000378:metabolism / Q000494:pharmacology*
D017077:Culture Media, Conditioned; D007328:Insulin; D018125:Receptors, Transforming Growth Factor beta; D014020:Tissue Extracts; D016212:Transforming Growth Factor beta; D004815:Epidermal Growth Factor; D004247:DNA