Differential involvement of DNases in HeLa cell apoptosis induced by etoposide and long term-culture

Abstract

We have applied to human HeLa cells two different stimuli of apoptosis: the antitumoral drug etoposide, and a morè physiological' death condition, obtained by growing cells in the same medium for long time periods, for up to 10 days. Analysis of different parameters demonstrated that in both experimental systems the same apoptotic features are visible. However, the DNA degradation pattern appeared to be different, suggesting the involvement of different DNases. In this view, we have analyzed the activity and expression of Ca 2+ -Mg 2+ -dependent and acid DNases. We have observed that DNase I is not modulated during apoptosis. In contrast, the acid L-DNase II (derived from Leukocyte Elastase Inhibitor by post-translational modification), recently identified in our laboratory, is mainly active in the apoptotic pathway induced by long term-culture. Furthermore, we have provided evidence that while caspase 3 is activated by both inducers, caspase 1 is essential only for the etoposide-induced apoptosis.

An antagonist of retinoic acid receptors more effectively inhibits growth of human prostate cancer cells than normal prostate epithelium

“…Endonuclease G is an apoptotic DNAase that is released from the mitochondria (Li et al, 2001), and etoposideinduced apoptosis in the HeLa cells involves caspase-independent activation of endonucleases (Torriglia et al, 1999). Indeed, triggering of caspase-independent cell death has been proposed as a means of combating cancer (reviewed in Sun et al, 2000;Mathiasen and Jaattela, 2002;Lewis et al, 2003).…”

Induction of acetylcholinesterase expression during apoptosis in various cell types

“…AChE activity was only observed in apoptotic cells. One such example is shown in Figure 1, where only apoptotic HLF human fibroblast cells ( Figure 1B) in long term-culture 33 appeared dark brown upon AChE cytochemical staining.…”

Activation of DNA-degrading enzymes during apoptosis

“…The conversion of LEI into L-DNase II is promoted by intracellular acidification (Altairac et al 2003a). In different cell lines, we showed an increased expression and a nuclear translocation of L-DNase II during apoptosis (Torriglia et al 1999;Belmokhtar et al 2000;Gorrini et al 2003). In Figure 2, western blot analysis of the conversion of LEI into L-DNase in apoptotic cells is reported.…”