Cancer Chemotherapeutic Agents Lecture 6 Dr. M Casely-Hayford: DNA Topoisomerases and Cancer Drug Development
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Questions and Answers

What is the main biological function of DNA topoisomerases?

  • Enhance DNA supercoiling
  • Synthesize new DNA strands
  • Repair damaged DNA strands
  • Cleave both strands of double-stranded DNA simultaneously (correct)

    • In the context of cancer drug development, what role do topoisomerases play?

  • They induce apoptosis in cancer cells
  • They repair damaged DNA in cancer cells
  • They are targets for anticancer drug development (correct)
  • They prevent cancer cell growth

    • How do Teniposide and etoposide relate to the mayapple plant?

  • They are used as fertilizers for the mayapple plant
  • They are toxins found in the mayapple plant
  • They are developed from the main constituent of the mayapple plant (correct)
  • They inhibit growth of the mayapple plant

    • What is the initial segment that Topoisomerase II binds before cleaving both DNA strands?

    <p>G segment (gate segment)</p> Signup and view all the answers

    What happens after the ATP binds to the two N-terminal domains of Topoisomerase II?

    <p>Brings the two domains together for a conformational change</p> Signup and view all the answers

    How does Topoisomerase II reset after hydrolysis of ATP?

    <p>The G segment remains bound with the enzyme in a resealed state</p> Signup and view all the answers

    What is the major mechanism of antineoplastic action of podophylotoxins?

    <p>Stabilizing the DNA-topo II cleavable complex</p> Signup and view all the answers

    Which isoform of topoisomerase II has two DNA independent binding sites?

    <p>Topo IIα</p> Signup and view all the answers

    What is the main difference between etoposide and teniposide?

    <p>Differ in their cellular uptake due to lipophilicity</p> Signup and view all the answers

    What is the purpose of solubility enhancers in IV formulations of topoisomerase II inhibitors?

    <p>To minimize hypersensitivity reactions</p> Signup and view all the answers

    When do topoisomerase II inhibitors have the most devastating effect on cells?

    <p>In S or early G2 phase of the cell cycle</p> Signup and view all the answers

    What is the role of podophylotoxins in interacting with Topo IIα?

    <p>Disrupting RNA transcription processes</p> Signup and view all the answers

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