Absence of expression of transforming growth factor-beta type II receptor is associated with an aggressive growth pattern in a @entity19 XXXX cell line, Renca.

@entity20357 @entity641 @entity19 @entity5 @entity665 @entity15136 @entity703
@entity641 ( @entity641 ) inhibits the proliferation of many @entity5 cells. However, @entity5 cells frequently become resistant to this inhibitory effect due to the absence of TGF-beta receptor (TbetaR) expression. This study reports the nature of TGF-beta sensitivity in an aggressive @entity19 @entity703 cell line, Renca, investigated in a series of experiments. The growth of Renca cells, in tissue culture, was not sensitive to the inhibitory effect of @entity641 with doses ranging from 0.1 to 10 ng./ml., nor was this cell line sensitive to the effect of @entity641 in inducing the expression of plasminogen activator inhibitor-I. Renca cells expressed @entity641 mRNA and protein, as determined by RT-PCR and ELISA, respectively. The level of @entity641 production by Renca cells was moderate, thus eliminating the possibility that endogenous @entity641 production might be masking the effect of TGF-beta sensitivity. Furthermore, Renca cells expressed @entity20357 mRNA, but did not express @entity15136 mRNA, suggesting that the absence of this receptor may be the cause of TGF-beta insensitivity. Additionally, a vector containing the @entity15136 cDNA was transiently transfected into Renca cells. The inhibitory effect of @entity641 was introduced in Renca cells after transfection with this receptor. At the same time, the growth rate of these cells diminished significantly when compared with that of the wild type Renca cells, as judged by the rate of @entity665 incorporation in the absence of any exogenous @entity641 . These observations demonstrated that Renca cells lack the functional @entity15136 and suggest that their aggressive growth pattern is due, at least in part, to their insensitivity to TGF-beta.
