Sulindac-induced Apoptosis without Oligonucleosomal DNA Fragmentation in HT-29 Cells: Its Special References to Mitochondrial Pathway

ABSTRACT

PURPOSE: This study was undertaken to reveal the molecular mechanism underlying sulindac-induced apoptosis in the human colon cancer cell line HT-29 (mutant p53). METHODS: Apoptosis was determined by using Hoechst 33342 staining, and translocation of proteins was established by using immunofluorescence, immunoelectron microscopy, and Western blotting after ultra- fractionation. RESULTS: This type of apoptosis was associated with decreased mitochondrial membrane potential, a translocation of the apoptosis-inducing factor (AIF) to the nucleus, and morphological evidence of nuclear condensation. However, DNA electrophoresis did not elucidate the ladder pattern of DNA fragments. Instead, a pulse-field gel electrophoresis showed that sulindac led to disintegration of nuclear DNA into-high- molecular-weight DNA fragments of about 100~300 kbp. CONCLUSIONS: Our findings indicate that sulindac induces large-scale DNA fragmentation, suggesting a predominantly AIF-mediated cell-death process, through translocation of the AIF to the nucleus in HT-29 cells.