title: Topoisomerase I activity in squamous cell carcinoma of the head and neck.
abstract: In recent preclinical and clinical trials, topoisomerase I inhibitors have shown great promise as antitumor agents. These agents are most effective against tumors with high topoisomerase I activity. Therefore, determining topoisomerase I activity in advance may predict response to topoisomerase I inhibitors. Squamous cell carcinoma of the head and neck and normal tissue samples were obtained from 12 patients. Cellular extracts were prepared, and topoisomerase I activity assays were performed. The results suggest that topoisomerase I activity in squamous cell carcinoma of the head and neck is increased approximately sixtyfold compared to normal tissue. Increased activity often correlates with clinical responsiveness; these results predict that topoisomerase I inhibitors should be effective and selective against squamous cell carcinoma of the head and neck.
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D005260:Female; D006258:Head and Neck Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D059004:Topoisomerase I Inhibitors
chemical_list: D004791:Enzyme Inhibitors; D059004:Topoisomerase I Inhibitors; D004264:DNA Topoisomerases, Type I