Antibody to human topo 1

Camptothecin was a gift of the Drug Synthesis and Chemistry Branch, Developmental Therapeutic Program of NCI, NIH. Topotecan hydrochloride was obtained from Cayman Chemicals (Ann Arbor, MI). A stock solution of camptothecin was prepared in DMSO, TPT was dissolved in doubly distilled water, and solutions were stored at −80°C. Ascorbic acid and horseradish peroxidase (HRP) were obtained from Sigma-Aldrich Chemical Company (St. Louis, MO). Ascorbic acid (100 mM) was dissolved in chelex-treated phosphate buffer and the pH of the solution was adjusted to 7.2 and stored at −80°C. Human myeloperoxidase was purchased from Lee Biosolutions (St. Louis, MO). Human topo I, antibody to Human topo I, and SDS/KCl precipitation assay kits were obtained from Topogen (Buena Vista, CO). Primary antibody for the analysis of p53 was obtained from Santa Cruz Biochemicals (Dallas, TX). Primary antibody anti-gamma H2AX, for the detection of DNA double-strand breaks, anti-p21, and anti-β-actin were obtained from Abcam (Cambridge, MA). DMPO was purchased from Dojindo (Rockville, MD) and used without any further purification.