Question

Malignant tumors are sometimes treated with drugs that halt mitosis, and thus stop the production of new cancer cells. Two such drugs, vincristine sulfate and vinblastine sulfate, interfere with the formation of spindle fibers. How could this action halt mitosis? Antibiotics such as mitomycin C and inorganic compounds such as cis-platinum also can be used to stop the growth of tumors. These drugs interfere with DNA synthesis in treated cells. How could this action halt mitosis?

Answer 1

Answer:

The inhibition of the formation of the mitotic spindle leads to the arrest of cells in metaphase, stopping cancer cells from dividing. Moreover, the inhibition of the DNA synthesis may also lead to cell cycle arrest, thereby also stopping cancer cells from proliferating.

Explanation:

Vinblastine Sulfate is a natural alkaloid that binds to the microtubules of the spindle apparatus in the S phase of the cell cycle, thereby arresting tumor cells in metaphase. Moreover, vinblastine sulfate is another alkaloid drug that alters the formation of microtubules in the cell cycle (mitosis). Mitomycin C  is a chemotherapeutic agent that produces interstrand DNA cross-links, thereby inhibiting DNA synthesis in tumor cells. Finally, cis-platinum is another chemotherapy agent that produces cross-links between DNA and proteins and thus arrests the cell cycle of tumor cells in the G1 phase.