Restoration of growth control in malignantly transformed mouse fibroblasts grown in a chemically defined medium.
The expression of growth control and morphological transformation was studied in methylcholanthrene-transformed C3H/10T 1/2 CL8 cells serially propagated in CDM by first exposing cells to albumin (0.1%) before dispersing them with trypsin (50 microgram/ml). In serum-supplemented media, methylcholanthrene-transformed C3H/10T 1/2 CL8 cells exhibit various aspects of the transformed phenotype such as irregular morphology, extensive cell overlap, lack of density-dependent inhibition of division, a saturation density of 1.1 X 10(5) cells/sq cm and tumorigenicity in vivo. Cell phenotype in CDM was dramatically altered. Methylcholanthrene-transformed C3H/10T 1/2 1/2 CL8 cells adapted to CDM exhibited a regular epithelioid morphology with no cell overlap and formed confluent monolayers of nonproliferating cells at a saturation density of 5 X 10(4) cells/sq cm. The mean generation time of logarithmic-phase cells was 25 to 27 hr. Reversion to the transformed phenotype followed addition of albumin (0.1%) or serum (2%) to logarithmic-phase cultures or exposure (30 to 60 sec) to trypsin (10 microgram/ml). Cultures in CDM reexposed to serum remained highly tumorigenic in vivo. The data suggest that absorbed proteins may block transformation-sensitive cell surface sites responsible for growth control and that these sites are inactivated by trypsin.
D000418:Albumins; D000818:Animals; D001345:Autoradiography; D001769:Blood; D002455:Cell Division; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced*; D003470:Culture Media; D005347:Fibroblasts / Q000187:drug effects*; D066298:In Vitro Techniques; D008748:Methylcholanthrene; D051379:Mice; D008809:Mice, Inbred C3H; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental; D010641:Phenotype; D014184:Transplantation, Homologous; D014357:Trypsin
D000418:Albumins; D003470:Culture Media; D008748:Methylcholanthrene; D014357:Trypsin