Anti-apoptotic Bcl-2 proteins: structure, function and relevance for radiation biology.
OBJECTIVE
Bcl-2 family members mediate anti-apoptotic signals in a wide variety of human cell systems. Despite its proven antiapoptotic function, several results indicate that overexpression of Bcl-2 is not clearly associated with increased radiation resistance in vitro or in vivo. The reasons for this obvious contradiction are not understood.


METHODS
Current data on the function of Bcl-2 as an anti-apoptotic protein, its role for the modulation of radiation sensitivity in vitro and its value as prognostic marker in vivo are reviewed.


RESULTS
Bcl-2 and related proteins are currently perceived to be the most important anti-apoptotic proteins. Their function is related to their ability to interfere with mitochondrial apoptosis pathways. Contradictory data have been published on the relevance of Bcl-2 and related family members for in vitro and in vivo tumour response. The value of Bcl-2 as a prognostic marker thus remains unclear.


CONCLUSIONS
Although Bcl-2-related proteins are currently the most relevant anti-apoptotic modulators, their relevance for radiation responses in vivo or in vitro remain undefined. Furthermore, their determination in a routine clinical setting does not appear to be justified.
Department of Radiation Oncology, University Tübingen, Hoppe Seyler Str. 3, D-72076 Tübingen, Germany. claus.belka@uni-tuebingen.de
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D017209:Apoptosis; D004249:DNA Damage; D006801:Humans; D008954:Models, Biological; D009369:Neoplasms / Q000473:pathology / Q000532:radiotherapy; D010766:Phosphorylation; D011379:Prognosis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D015398:Signal Transduction
D019253:Proto-Oncogene Proteins c-bcl-2