An alteration in the structure of topoisomerase II that maintained its functional activity but prevented the action of inhibitory compounds would render useless the action of which of the following chemotherapeutic agents?
A) alkylating drugs
B) anthracyclins
C) antimetabolites
D) camptothecins
E) taxanes

Question

Quizplus · Accepted Answer

Anthracyclins work by inhibiting topoisomerase II, so if the enzyme's structure is altered to prevent inhibition by these compounds, the drugs would be ineffective.  The anthracyclins were originally isolated from the fungus, Streptomyces. Doxorubicin (Adriamycin, Doxil, Rubex) and daunorubicin (Cerubidine, DaunoXome, Daunomycin, Rubidomycin) have similar modes of action, although doxorubicin is the more potent of the 2 and is used in the treatment of breast cancers, lymphomas, and sarcomas. The anthracyclins inhibit the actions of topoisomerase II.

An Alteration in the Structure of Topoisomerase II That Maintained