Acquisition of resistance to apoptosis and necrosis by Bcl-xL over-expression in rat hepatoma McA-RH8994 cells.
BACKGROUND
Bcl-xL is the predominant anti-apoptotic Bcl-2 family member in the liver. Suppression of cell death promotes carcinogenesis and contributes to resistance to radiation and chemotherapeutic agents.


METHODS
Direct effects of Bcl-xL protein on apoptosis and necrosis were investigated in rat hepatoma cells. Rat hepatoma cell line McA-RH8994 cells were transfected with expression plasmids containing a whole coding sequence of rat bcl-xL cDNA of sense orientation. Stable transfectant cell lines expressing bcl-xL cDNA (designated as RH8994/Bcl-xL-S), or control plasmid DNA (designated as RH8994/pT) were established.


RESULTS
Cellular amounts of Bcl-xL in RH8994/Bcl-xL-S cells were demonstrated to be more than 20-fold that of RH8994/pT and parental cells. Three independent clones of RH8994/Bcl-xL-S were isolated and their susceptibility to various cell death stimuli was compared with that of the control cells. Transforming growth factor-beta1 and tumour necrosis factor-alpha induced apoptosis dose dependently in these cells, but the 50% cytotoxicity concentrations of these factors in RH8994/Bcl-xL-S cells were more than 10-fold higher than those in RH8994/pT and parental cells. Similarly, RH8994/Bcl-xL-S cells were shown to be significantly less susceptible to necrotic cell death induced by a calcium ionophore, A23187; a mutagen, N-methyl-N'-nitro-N-nitrosoguanidine; and UV-irradiation when compared with the control cells.


CONCLUSIONS
Over-expression of Bcl-xL was shown to provide protection against apoptotic and necrotic cell death in rat hepatoma cells.
Fukuda
K
K
Department of Oriental Medicine, Gifu University School of Medicine, Japan. kfukuda@cc.gifu-u.ac.jp
Yamamoto
M
M
D000818:Animals; D017209:Apoptosis; D000001:Calcimycin / Q000494:pharmacology; D016923:Cell Death / Q000235:genetics / Q000528:radiation effects; D015870:Gene Expression; D007476:Ionophores / Q000494:pharmacology; D008114:Liver Neoplasms, Experimental / Q000378:metabolism* / Q000473:pathology*; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D009153:Mutagens / Q000494:pharmacology; D009336:Necrosis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014466:Ultraviolet Rays; D051020:bcl-X Protein
C494813:Bcl2l1 protein, rat; D007476:Ionophores; D009153:Mutagens; D019253:Proto-Oncogene Proteins c-bcl-2; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D051020:bcl-X Protein; D008769:Methylnitronitrosoguanidine; D000001:Calcimycin