Phenotypic alterations in fibroblasts and fibrosarcoma cells that overexpress latent transforming growth factor-beta 1.
Mouse embryo-derived AKR-2B fibroblasts and murine fibrosarcoma cells (the 1591 cell line) were transfected with a murine transforming growth factor-beta 1 (TGF beta 1) cDNA under the transcriptional control of either the simian virus-40 early promoter or the cytomegalovirus promoter/enhancer. Selected clones secreted 2- to 4-fold more TGF beta-competing activity into their media than the parental cell line or neomycin-transfected controls. The TGF beta 1 released into the cell-conditioned medium was latent. Despite the latency of the overexpressed TGF beta 1, TGF beta 1-transfected cells exhibited phenotypic features of TGF beta 1-treated cells. When confluent, the TGF beta 1-transfected cells had the morphological characteristics of the parental cells that have been treated with active TGF beta 1. AKR-2B cells that expressed higher levels of TGF beta 1 also expressed high levels of c-sis and c-myc mRNAs and decreased TGF beta 2 and TGF beta 3 mRNAs in the same manner as parental AKR-2B cells that had been treated with active TGF beta 1. The transfected 1591 cells that overexpressed TGF beta 1 bound less [125I]TGF beta 1 than did parental 1591 cells, but after a mild acid wash demonstrated an increase in [125I]TGF beta 1 binding. Our results suggest that these TGF beta 1-transfected fibroblast and fibrosarcoma cells have the capacity to activate TGF beta; however, as very little activated TGF beta is detected in the medium, it is hypothesized that these cells activate latent TGF beta 1 and bind the activated TGF beta 1, thus acquiring a phenotype consistent with TGF beta 1-treated cells.
Beauchamp
R D
RD
Department of Surgery, University of Texas Medical Branch, Galveston 77550.
Sheng
H M
HM
Bascom
C C
CC
Miller
D A
DA
Lyons
R M
RM
Torre-Amione
G
G
Moses
H L
HL
D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D004622:Embryo, Mammalian; D005347:Fibroblasts / Q000502:physiology; D005354:Fibrosarcoma; D015870:Gene Expression; D007700:Kinetics; D051379:Mice; D008809:Mice, Inbred C3H; D010641:Phenotype; D010957:Plasmids; D011061:Poly A / Q000235:genetics / Q000302:isolation & purification; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger; D011956:Receptors, Cell Surface / Q000378:metabolism; D018125:Receptors, Transforming Growth Factor beta; D012513:Sarcoma, Experimental; D013498:Suramin / Q000494:pharmacology; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism
D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D011061:Poly A; D013498:Suramin; D012313:RNA