Platelet-derived growth factor (PDGF) B and A homodimers transform murine fibroblasts depending on the genetic background of the cell.

H R Kim,S Upadhyay,S Korsmeyer,T F Deuel

doi:10.1016/s0021-9258(18)43856-2

Abstract

The endogenously overexpressed c-sis (platelet-derived growth factor (PDGF) B-chain) proto-oncogene and its viral counterpart v-sis effectively transform NIH 3T3 cells by an autocrine mechanism, whereas the PDGF A-chain gene does not. However, PDGF B continuously cultured with confluent NIH 3T3 cells fails to induce phenotypic transformation as would be predicted by the autocrine model. We now have established conditions in which subconfluent, logarithmically growing NIH 3T3 cells are efficiently transformed by exogenous PDGF B but not PDGF A. Clonally selected cells from transformed foci remain transformed when continuously cultured with PDGF B but revert to the non-transformed phenotype without PDGF B or if PDGF A is substituted for PDGF B, suggesting that PDGF B complements a genetically stable NIH 3T3 cell phenotype to induce transformation and initiates a signal different from that of PDGF A required to induce transformation. Neither PDGF A nor PDGF B transform normal rat kidney (NRK) cells under identical conditions of culture. However, we now demonstrate that exogenous PDGF A and PDGF B independently transform NRK cells that endogenously overexpress the anti-apoptotic bcl-2 gene. These results suggest that both PDGF A and PDGF B effectively transform murine fibroblasts with a compatible genotype, that transformation by the PDGF isoforms requires complementation with a compatible genotype in a multistep transformational process, and that the autocrine mechanism is required but not sufficient for transformation of murine fibroblasts by PDGF.

Highlights

The endogenouslyoverexpressed c-sis (platelet-de- malignancy (Waterfield et al, 1983; Doolittle et al, 1983; Deuel rivedgrowthfactor(PDGF)B-chain)proto-oncogene et al, 1983)(reviewed by Deuel (1987))
Cally growing NIH 3T3 cells are efficiently transformed According to the autocrine hypothesis
The first evidence to the non-transformed phenotype without PDGF B or if directly support the autocrine hypothesis and to suggest the PDGF A is substituted for PDGFB, suggesting that PDGF B complements a genetically stable NIH 3T3 cell phenotype to induce transformation andinitiates a signal different from that of PDGF A required to induce transformation

Summary

Introduction

The endogenouslyoverexpressed c-sis (platelet-de- malignancy (Waterfield et al, 1983; Doolittle et al, 1983; Deuel rivedgrowthfactor(PDGF)B-chain)proto-oncogene et al, 1983)(reviewed by Deuel (1987)). NIH 3T3 cells were transfected with thev-sis gene undercontrol of the Moloney murine leukemiavirus long terminal repeat sequences (Bejcek et al, 19891, stable transfectants wereselected with G418, and theefficiencies of transformationinduced by external or internalstimulation were tivities of PDGF Aand B homodimers were assessed to establish opti- determined by comparison of positive colonies (diameter mum concentrations requirefdor a maximum mitogenic response and tgoreater than 1 mm) in soft agar after 2 weeks of growth.

Results

Conclusion