TGF-beta1 inhibition of apoptosis through the transcriptional up-regulation of Bcl-X(L) in human monocytic leukemia U937 cells.
To characterize the TGF-beta1 response of monocytic leukemia cells, we analyzed the effects of TGF-beta1 on cell proliferation, differentiation, and apoptosis of human monoblastic U937 cells. Treatment of cells with TGF-beta1 in the absence of growth factors significantly enhanced cell viability. Flow cytometric analysis of DNA content and CD14 expression revealed that TGF-beta1 does not affect cell proliferation and differentiation. Consistent with these results was the finding that no transcriptional induction of Cdk inhibitors such as p21Waf1, p15Ink4b, and p27Kip1 was detected following TGF-beta1 treatment. Interestingly, however, pretreatment of TGF-beta1 significantly inhibited Fas-, DNA damage-, and growth factor deprivation-induced apoptosis. This antiapoptotic effect was totally abrogated by anti-TGF-beta1 antibody. Quantitative RT-PCR analysis demonstrated a dose- and time-dependent transcriptional up-regulation of Bcl-X(L), suggesting its implication in the TGF-1-mediated antiapoptotic pathway. We also observed elevated expression of c-Fos and PTEN/MMAC1. But, no detectable change was recognized in expression of c-Jun, Fas, Fadd, Fap-1, Bcl-2, and Bax. Taken together, our study shows that TGF-beta1 enhancement of cellular viability is associated with its antiapoptotic effect, which may result from the transcriptional up-regulation of Bcl-X(L).
Lee
J
J
Department of Pathology, College of Medicine, Kyung Hee University, Seoul, Korea. Leejuhie@chollian.net
Park
B J
BJ
Park
J H
JH
Yang
M H
MH
Chi
S G
SG
D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004247:DNA / Q000032:analysis; D004249:DNA Damage; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D016147:Genes, Tumor Suppressor / Q000235:genetics; D006801:Humans; D007951:Leukemia, Myeloid / Q000235:genetics; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D051059:PTEN Phosphohydrolase; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D025521:Tumor Suppressor Proteins; D020298:U937 Cells; D015854:Up-Regulation; D051020:bcl-X Protein; D019014:fas Receptor / Q000378:metabolism
C494811:BCL2L1 protein, human; D018950:Lipopolysaccharide Receptors; D009363:Neoplasm Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D016212:Transforming Growth Factor beta; D025521:Tumor Suppressor Proteins; D051020:bcl-X Protein; D019014:fas Receptor; D004247:DNA; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human