Hexamethylene bisacetamide (HMBA)-induced nuclear damage indicative of apoptosis.

(A) CCRF and A7 CEM cells were untreated or cultured for 48 hours with 10 mmol/L HMBA or for 4 hours with 100 ng/mL anti-Fas antibody (CH-11). Genomic DNA was extracted and run on a 2% agarose gel. CCRF and A7 CEM cells were treated for 48 hours with 10 mmol/L HMBA and assayed by TUNEL for DNA fragmentation as denoted by an increase in mean channel fluorescence (B) and Hoechst 33 258 staining (C) for chromatin condensation. The percentage of TUNEL-positive cells are shown above each histogram, and cells displaying chromatin condensation are indicated by an arrow. Lysates from CCRF and A7 cells treated for 72 hours with 0-20 mmol/L HMBA were separated by SDS-PAGE, and Western blots were performed using polyclonal anti-PARP antibody (D). The active form of PARP migrates as a 118-kD protein and cleaved to an inactive form of approximately 89 kd.