Transient induction of apoptosis in serum-starved glioma cells by insulin and IGF-1.
Insulin has a wide variety of biological effects. One of them is a mitogen-like activity whereby cell proliferation is stimulated. In this study we found a heretofore unreported insulin-elicited transient apoptosis of glioma cells. When serum-starved glioma cells were fed with a fresh regular medium, in the 6- to 12-h post-starvation period, the growth rate as determined by cell number was significantly suppressed by insulin, although cell cycle progression and DNA synthesis were actually accelerated. Increase in apoptosis in those growth-retarded cultures was demonstrable by Hoechst staining, detection of histone-associated DNA fragment, and in situ cell death detection. Apoptosis occurred among cells in all stages of cell cycle. After 24 h post-starvation, insulin increased the total cell number like a typical growth-promoting mitogen. In this regard, IGF-1, but not EGF nor TGF-beta 1, behaved like insulin.
Yang
B C
BC
Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC. y1357@mail.ncku.edu.tw
Chang
H M
HM
Wang
Y S
YS
Chen
R F
RF
Lin
S J
SJ
D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D016895:Culture Media, Serum-Free; D004261:DNA Replication; D004815:Epidermal Growth Factor / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D016895:Culture Media, Serum-Free; D007328:Insulin; D016212:Transforming Growth Factor beta; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I