How do cancer cells develop resistance to chemotherapy?

How do cancer cells develop resistance to chemotherapy?

• A. MDR1 ATP-dependent efflux pump
• B. Increased apoptosis
• C. Decreased metabolism
• D. Increased immune clearance

Answer: (A)

Cancer cells often become resistant to chemotherapy by lowering the drug concentration inside the cell. A major way this happens is through overexpression of efflux pumps, such as MDR1, which encodes P-glycoprotein. This transporter uses ATP to actively push a wide range of chemotherapy drugs out of the cell, so intracellular drug levels stay too low to cause the intended damage. Because the pump affects many different drugs, it’s a classic mechanism of multidrug resistance. If apoptosis were increased, chemotherapy would kill more cancer cells instead of letting them survive. Decreased metabolism might alter some drug effects in specific contexts but doesn’t reliably explain resistance to many standard agents. Increased immune clearance would help remove cancer cells rather than enable resistance.

Cancer cells often become resistant to chemotherapy by lowering the drug concentration inside the cell. A major way this happens is through overexpression of efflux pumps, such as MDR1, which encodes P-glycoprotein. This transporter uses ATP to actively push a wide range of chemotherapy drugs out of the cell, so intracellular drug levels stay too low to cause the intended damage. Because the pump affects many different drugs, it’s a classic mechanism of multidrug resistance.

If apoptosis were increased, chemotherapy would kill more cancer cells instead of letting them survive. Decreased metabolism might alter some drug effects in specific contexts but doesn’t reliably explain resistance to many standard agents. Increased immune clearance would help remove cancer cells rather than enable resistance.