Induction of apoptosis in CTLL-2 cells by protocatechualdehyde

The purpose of this study was to investigate the possible molecular mechani sms of the antiproliferative effect induced by protocatechualdehyde (PA, a dihydroxybenzene derivative). The viability of cytotoxic T cells (CfLL-2) s timulated by IL2 was significantly inhibited at 0.12 mM PA. This inhibitory effect was associated with the induction of apoptosis detected by DNA frag mentation assay. DNA ladder appeared at 0.12 mM PA and the intensity of DNA ladder was visible at 0.3 mM PA. PA inhibited the Ib2-dependent tyrosine p hosphorylation of 91, 80 and 55 KDa proteins, but did not affect IL2-depenc tent serine/threonine phosphorylation of proteins. The levels of bcl-2 prot ein and mRNA were suppressed by PA. An alteration in bax protein expression on the apoptosis process in CTLL-2 cells was not observed. However, caspas e-3 activity was increased by PA. Our results demonstrate that PA inhibited cell proliferation and induced apoptosis in CTLL-2 cells. It is concluded that PA is a potent anti-proliferative agent and is expected to be a promis ing candidate for novel therapeutics.