Thiopurine treatment of human leukemia cells deficient in components of the mismatch repair system (Nalm6) initiated apoptosis after incorporation into DNA, as revealed by caspase activation and terminal deoxynucleotidyl transferase-mediated nick end100-106 labeling assay. To elucidate the cellular sensor(s) responsible for recognition of DNA damage in cells with an inactive mismatch repair system, we isolated a multiprotein nuclear complex that preferentially binds DNA with thioguanine incorporated. The components of this nuclear multiprotein complex, as identified by protein mass spectroscopy, included high mobility group proteins 1 and 2 (HMGB1, HMGB2), heat shock protein HSC70, protein disulfide isomerase ERp60, and glyceraldehyde 3-phosphate dehydrogenase. The same complex was also shown to bind synthetic oligodeoxyribonucleotide duplexes containing the nonnatural nucleosides 1-β-D-arabinofuranosylcytosine or 5-fluoro-2′-deoxyuridine. Fibroblast cell line derived from Hmgb1-/- murine embryos had decreased sensitivity to thiopurines, with an IC50 10-fold greater than Hmgb1-proficient cells (P <0.0001) and exhibited comparable sensitivity to vincristine, a cytotoxic drug that is not incorporated into DNA. These findings indicate that the HMGB1-HMGB2-HSC70-ERp60-glyceraldehyde 3-phosphate dehydrogenase complex detects changes in DNA structure caused by incorporation of non-natural nucleosides and is a determinant of cell sensitivity to such DNA modifying chemotherapy.
|Number of pages||7|
|Publication status||Published - Jan 1 2003|
ASJC Scopus subject areas
- Cancer Research