What enzyme is inhibited by etoposide -
Ans. is 'b' i.e., Topoismerase II Etoposide* It is a semisynthetic derivative of podophyllotoxin, a plant glycoside.* It is not a mitotic inhibitor, but arrests cells in the G2 phase and causes DNA breaks by affecting DNA topoisomerase-2 function.* While the cleaving of double stranded DNA is not interfered, the subsequent resealing of the strand is prevented.* Etoposide is used in testicular tumours, lung cancer, Hodgkin's and other lymphomas, carcinoma bladder and stomach. Alopecia, leucopenia and g.i.t. disturbances are the main toxicity. Oral bioavailability is 50%; oral dose is double than i.v. dose.
Topoisomerase I
Topoismerase II
Dihydrofolate reductase
Dihydro orotate oxidase
Anti-Cancer