Many effective anticancer drugs function as such by interfering with processes of DNA replication. The drug, doxorubicin, is useful in the treatment of lymphomas and breast cancers because of its ability to interfere with which of the following enzyme activities?
A) DNA ligase
B) DNA polymerase a
C) primase
D) topoisomerase II
E) uracil N-glycosylase

Question

Quizplus · Accepted Answer

Doxorubicin interferes with the activity of topoisomerase II, an enzyme that helps manage DNA supercoiling and is crucial for DNA replication and cell division. By inhibiting this enzyme, doxorubicin disrupts DNA replication, leading to cell death, which is effective in treating certain cancers.  Doxorubicin is a drug of the class that functions by interfering with topoisomerases. In particular, doxorubicin inhibits topoisomerase II. During the process of DNA replication, the 2 strands of the DNA helix are separated. As the replication fork progresses toward sites of chromosomal attachment to the scaffold, there is an increase in the torsional stress on the helix due to supercoiling. These torsional stresses are relieved by the action of topoisomerases that introduce nicks into the DNA, which allows the strands to unwind the supercoils. Topoisomerase I introduces single-strand nicks, whereas topoisomerase II introduces double-strand nicks. Interference with the action of topoisomerases would thus impair the rate of DNA replication and this would be detrimental for rapidly proliferating cells such as cancer.

Many Effective Anticancer Drugs Function as Such by Interfering with Processes