PARP degradation in apoptotic Syrian hamster embryo (SHE) cells compared to HL60 cell line

In this study, we attempted to identify apoptotic Syrian hamster embryo (SHE) cells by detecting the specific cleavage of poly(ADP-ribose)polymerase (PARP). Apoptosis was unequivocally identified in serum-deprived SHE cells. After protein electrophoresis and transfer, the anti-PARP antibody (C-2-10) was applied in order to visualize PARP degradation and the anti-polymer antibody (LP96-10) was used to identify PARP and its expected 89-kDa fragment on the membrane after renaturation and NAD+ addition. Results showed that PARP rapidly disappeared during apoptosis in SHE cells, but the resulting fragment remained undetectable with the anti-PARP antibody and no stable polymerase activity of this fragment was measured using anti-polymer antibody. Serum-starved SHE cells were compared to the etoposide-treated HL60 cell line as a control for typical apoptosis-related PARP cleavage. These results underline the fact that while PARP degradation is a criterion for apoptosis, the diagnosis of apoptosis can not rely exclusively on the appearance of its 89-kDa fragment as this signal may fail to appear in some cell systems.