TY - JOUR
T1 - Selective activation of Ha-ras(Val12) oncogene increases susceptibility of NIH/3T3 cells to TNF-α
AU - Chang, Meng Yao
AU - Won, Shen Jeu
AU - Yang, Bei Chang
AU - Jan, Ming Shiou
AU - Liu, Hsiao Sheng
N1 - Funding Information:
We thank H. J. Chang for correction of the manuscript. This work was supported by grants from the National Science Council, Taiwan, Republic of China (NSC86-2314-B-006-050 and NSC88-2314-B006-018).
PY - 1999/5/1
Y1 - 1999/5/1
N2 - This is the first report demonstrating that NIH/3T3 fibroblasts utilize the Raf-1/MAPK pathway to sensitize themselves to tumor necrosis factor-α (TNF-α) cytotoxicity under Ha-ras(Val12) oncogene-overexpressed conditions. This paper clearly shows that the sensitivity of NIH/3T3 cells to TNF-α cytotoxicity positively correlated with the expression level of activated Ha- ras transgene, which was manipulated either positively by isopropyl-β-D- thiogalactoside (IPTG) induction or negatively by a ribozyme or a dominant negative Ras suppression. Further analysis revealed that after TNF-α treatment, Ha-ras-overexpressed transformants underwent apoptosis. Overexpression of dominant negative Raf-1, Rac1, or RhoA in the Ha-ras transformants clarified that among these factors, only dominant negative Raf- 1 could reverse the cell sensitivity to TNF-α, indicating that Raf-1, as a proapoptotic factor, indeed participates in TNF-α cytotoxicity. The anti- apoptotic roles of Bcl-2 and PI(3) kinase are also demonstrated by the Ha-ras transformants which became more resistant to TNF-α while overexpressing Bcl- 2 or the activated p110 catalytic subunit. The analyses of the cell cycle and nuclear transcription factor activities revealed that TNF-α treatment caused the Ha-ras overexpressed transformants to shift from S to G0/G1 phase and increased the responses of AP-1, c-fos, and c-myc. Taken together, we suggest that the possible action of Ha-ras overexpression to sensitize TNF-α-treated fibroblasts is predominantly through the Ras/Raf-1/MAPK pathway to increase the responses of AP-1, c-fos, and c-myc, which are possibly involved in the aberration of cell cycle machinery, and subsequently to turn on the death pro- gram.
AB - This is the first report demonstrating that NIH/3T3 fibroblasts utilize the Raf-1/MAPK pathway to sensitize themselves to tumor necrosis factor-α (TNF-α) cytotoxicity under Ha-ras(Val12) oncogene-overexpressed conditions. This paper clearly shows that the sensitivity of NIH/3T3 cells to TNF-α cytotoxicity positively correlated with the expression level of activated Ha- ras transgene, which was manipulated either positively by isopropyl-β-D- thiogalactoside (IPTG) induction or negatively by a ribozyme or a dominant negative Ras suppression. Further analysis revealed that after TNF-α treatment, Ha-ras-overexpressed transformants underwent apoptosis. Overexpression of dominant negative Raf-1, Rac1, or RhoA in the Ha-ras transformants clarified that among these factors, only dominant negative Raf- 1 could reverse the cell sensitivity to TNF-α, indicating that Raf-1, as a proapoptotic factor, indeed participates in TNF-α cytotoxicity. The anti- apoptotic roles of Bcl-2 and PI(3) kinase are also demonstrated by the Ha-ras transformants which became more resistant to TNF-α while overexpressing Bcl- 2 or the activated p110 catalytic subunit. The analyses of the cell cycle and nuclear transcription factor activities revealed that TNF-α treatment caused the Ha-ras overexpressed transformants to shift from S to G0/G1 phase and increased the responses of AP-1, c-fos, and c-myc. Taken together, we suggest that the possible action of Ha-ras overexpression to sensitize TNF-α-treated fibroblasts is predominantly through the Ras/Raf-1/MAPK pathway to increase the responses of AP-1, c-fos, and c-myc, which are possibly involved in the aberration of cell cycle machinery, and subsequently to turn on the death pro- gram.
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U2 - 10.1006/excr.1999.4436
DO - 10.1006/excr.1999.4436
M3 - Article
C2 - 10222151
AN - SCOPUS:0033134102
SN - 0014-4827
VL - 248
SP - 589
EP - 598
JO - Experimental Cell Research
JF - Experimental Cell Research
IS - 2
ER -