[Bcl-2 inhibits p53-induced apoptosis after genotoxic damage by inhibitors of nuclear import of p53].
The tumor suppressor gene p53 in overexpressed in 50% of colorectal carcinomas and is an interesting target for gene therapeutic approaches. Furthermore the protooncogen bcl-2 is known to inhibit p53 induced apoptosis and is expressed in some colorectal carcinomas. In this study mechanism of bcl-2 cell death inhibition after p53 induction were evaluated. The human colon carcinoma cell line RKO posses wild-type p53 and also expresses bcl-2 protein. RKO cells were treated with liposomal bcl-2 antisense oligonucleotides (AS), control oligonucleotides (CO) and empty liposomes (EL) resulting in decreased bcl-2 expression. After induction of p53 with gamma-irradiation p53 protein expression was induced in AS, CO and EL pretreated cells. Microscopy and immunoblotting was used to characterize subcellular localization of p53 protein. Further p53 subcellular localisation was examined after p53 transfer of wt p53 cDNA in three bcl-2 expressing cell lines. Most of the p53 protein remained localized in the cytosol and apoptosis was decreased in bcl-2 expressing cells assessed by flow cytometric analysis (Ao). Our data suggests that bcl-2 is able to modulate transmembrane trafficking of p53. This resulted in inhibition of cell death implicating that bcl-2 function is involved in regulation of transmembrane gradients.
D021581:Active Transport, Cell Nucleus / Q000235:genetics / Q000528:radiation effects; D017209:Apoptosis / Q000235:genetics* / Q000528:radiation effects; D002467:Cell Nucleus / Q000473:pathology*; D003110:Colonic Neoplasms / Q000235:genetics* / Q000473:pathology*; D015972:Gene Expression Regulation, Neoplastic / Q000528:radiation effects; D006801:Humans; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D020320:Oligoribonucleotides, Antisense / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology*; D014407:Tumor Cells, Cultured / Q000473:pathology* / Q000528:radiation effects; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors* / Q000235:genetics*
D020320:Oligoribonucleotides, Antisense; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53