S. Kizaka-kondoh et al., Role of TGF-beta in EGF-induced transformation of NRK cells is sustaining high-level EGF-signaling, FEBS LETTER, 466(1), 2000, pp. 160-164
We have been isolating and analyzing NRK cell mutants, which fail to transf
orm by epidermal growth factor (EGF) and transforming growth factor (TGF)-b
eta. One such mutant, R14, can respond to the growth inhibitory signal of T
GF-beta to the same extent as parental NRK but fail to respond to the growt
h stimulatory signal of EGF, This mutant has a defect in EGF receptor (EGFR
) expression. When R14 mutant expressed a high level of EGFR, however, EGF
not only induced proliferation in this mutant but also induced transformati
on without the aid of TGF-beta. These findings suggest that the major role
of TGF-beta in this transformation system should be to counteract the ligan
d-dependent down-regulation of EGFR, thereby sustaining high-level EGF-sign
aling. (C) 2000 Federation of European Biochemical Societies.