Question

Multidrug resistance to chemotherapeutic drugs occurs because a. cancer cells can use plasma membrane carriers to pump drugs out of the cell. b. one drug may interfere with the activity of another drug. c. using several drugs at once will overtax the patient's immune system. d. using several drugs at once decreases the effectiveness of radiation therapy.

Short answer

Multidrug resistance to chemotherapeutic drugs occurs mainly because cancer cells can use plasma membrane carriers, such as ATP-binding cassette (ABC) transporters, to pump drugs out of the cell, leading to a decreased accumulation of the drugs inside cancer cells and making them less effective. The correct answer is option a.

Step-by-step solution

Option a: Cancer cells can use plasma membrane carriers to pump drugs out of the cell.

Option a is the correct answer. Cancer cells can develop multidrug resistance by using specific transport proteins in their plasma membrane, such as ATP-binding cassette (ABC) transporters, to pump chemotherapeutic drugs out of the cell. This process ultimately leads to the decreased accumulation of the drugs inside cancer cells, making the drugs less effective.

Option b: One drug may interfere with the activity of another drug.

Option b is incorrect. Although drug interactions can sometimes affect the effectiveness of individual drugs, the phenomenon of multidrug resistance in cancer cells is not primarily due to drug interactions. Instead, it is a result of cellular mechanisms like the increased expression of drug efflux transporters which decrease the intracellular drug concentrations.

Option c: Using several drugs at once will overtax the patient's immune system.

Option c is incorrect. The use of multiple drugs can sometimes place a considerable burden on the patient's body, but it is not the main reason for multidrug resistance in cancer cells. In fact, combination chemotherapy can often lead to better outcomes, as different drugs can target various aspects of cancer cell growth and survival, lowering the risk of developing resistance to one specific drug.

Option d: Using several drugs at once decreases the effectiveness of radiation therapy.

Option d is incorrect. The simultaneous use of several drugs does not necessarily decrease the effectiveness of radiation therapy. Rather, some chemotherapeutic drugs can actually enhance the effects of radiation therapy by making cancer cells more sensitive to radiation-induced damage.