Answer to Question #147791 in Genetics for Renee

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

Cancer results from uncontrolled cell division, which occurs due to mutations in genes. The three types of skin cancer are: Basal cell carcinoma (non-melanoma type) Squamous cell carcinoma (non-melanoma type) and Melanoma. The common causes of skin cancer are exposure to UV-radiation and carcinogens, etc. For example, people with fair skin and more moles are at increased risk of developing melanoma.

Vincristine (vinca alkaloids), is marketed under the trade name of Oncovin and it is also called leurocristine. This drug mostly used for the treatment of acute myeloid and lymphocytic leukemia. This compound was first isolated in 1961 from Catharanthus roseus.

Vincristine and vinblastine can easily diffuse into the cells, so it interferes at the metaphase of the cell cycle by binding with tubulin proteins and stop the segregation of chromosomes thus, block cancer cells' “mitosis process”. Therefore, that particular cell will be driven into apoptosis. Although it has minor side effects, namely nausea, vomiting, abdominal discomfort, and dose-related bone marrow depression.

Mitomycin C and cis-platinum can cause inhibition of DNA synthesis by N-alkylation of nitrogen bases in DNA thus, crosslinking occurs at the time of DNA synthesis. This mechanism is leading to inhibition of tumor cell division due to lack of required protein synthesis.