Resveratrol causes arrest in the S-phase prior to Fas-independent apoptosis in CEM-C7H2 acute leukemia cells

Resveratrol (3,5,4'-trihydroxy-trans-stilbene), in the concentration range of 20 mu M and above, induced arrest in the S-phase and apoptosis in the T cell-derived I-ALL lymphocytic leukemia cell line CEM-C7H2 which is deficie nt in functional p53 and p16, Expression of transgenic p16/INK4A, which cau ses arrest in G0/G1, markedly reduced the percentage of apoptotic cells, An tagonist antibodies to Fas or FasL, or constitutive expression of crmA did not diminish the extent of resveratrol-induced apoptosis, Furthermore, a ca spase-8-negative, Fas-resistant Jurkat cell line was sensitive to resveratr ol-induced apoptosis which could be strongly inhibited in the Jurkat as wel l as in the CEM cell line by z-VAD-fmk and z-IETD-fmk. The almost complete inhibition by z-IETD-fmk and the lack of inhibition by crmA suggested caspa se-6 to be the essential initiator caspase, Western blots revealed the mass ive conversion of procaspase-6 to its active form, while caspase-3 and casp ase-2 were proteolytically activated to a much lesser extent.