Question

Be able to explain the mechanism of action of the following anti-cancer drugs: Methotrexate, cisplatin, doxorubicin, Taxol, Vinblastine, Herceptin, and Avastin.

I NEED HELP IN ORDER TO UNDERSTAND BETTER. THANK YOU.

Answer 1

1. Methotrexate competitively inhibits dihydrofolate reductase enzyme (DHFR), thus inhibiting de novo synthesis of thymine in DNA synthesis. It is an antimetabolite.

2. Cisplatin is cytotoxix to cancer cells. It causes abnormal DNA linkages, thereby affecting G1, S phases. and ultimately promoting apoptosis.

3. Duxorubicin causes intercalation in the DNA. It is also known to inhibit the enzyme topoisomerase 2 which interferes in DNA transcription and replication. It also enhances quinone free radical production increasing cytotoxicity.

4. Taxol inhibits mitosis by inhibiting microtubule function. This causes disruption of spindle assembly, chromosome separation and ultimately division.

5. Vinblastine affects the mitotic spindles during replication. This causes arresting of replicating cells in M phase.

6. Herceptin (or Trastuzumab) is a monoclonal antibody and works by attching itslef to the Her2+ cells thus inhibiting the cells from receiving the growth signals. This is used for treatment of breast cancer.

7. Avastin (or Bevacizumab) binds to the vascular endothelial growth factor or VEGF. This helps prevent formation of new blood vessels thus impairing blood supply to cancer cells.