What is Chemotherapy and How Does it Work?
Chemotherapy and radiation are the two most popular treatments given to cancer patients. Chemotherapy is usually given as a combination of multiple anti-cancer drugs, and one of the main ways in which these drugs work is by inhibiting mitosis, or cell division. However, there are different kinds of chemotherapy, and depending on the type of cancer one has, the different agents or combinations of agents are usually tailored to have curative benefits, and are usually administered in cycles.
TYPES OF CHEMOTHERAPY
Alkylating agents were originally derived from a sulphur molecule known as mustard gas, and they are termed alkylating agents due to their ability to alkylate molecules. Now alkylation means the transfer of an alkyl group from one molecule to another, and this transfer can have numerous effects including inducing stable or unstable molecules. In the body, these alkylating agents can transfer an alkyl group to DNA and can have anti-cancer benefits. In order for your cells to grow and divide, the double-stranded DNA in your body must come a part and replicate. Alkylating agents may bind twice to one DNA strand, or the may bind once to two strands. In this way, the cells are unable to undergo correct cell division and they can break. This leads to cell death, and thus the death of cancer cells.
These molecules are derived from plants and are also known as plant alkaloids. These agents work by blocking the cancer cell when it is dividing. They inhibit this cell division primarily by inhibiting the function of microtubules, which are molecules that help to provide structure and shape to cells. They also play a role in helping your DNA to move around the cell at certain stages when the cell is dividing. And thus, if microtubules are inhibited, you can not have successful cell division of cancer cells. The two most widely known anti-microtubule agents are Vinca alkaloids which are derived from the periwinkle plant, and taxanes. In addition, these plants may also affect the normal growth and function of blood vessels which are essential for tumor growth and metastasis.
Antimetabolites are a group of molecules that are responsible for interfering with DNA and RNA synthesis. The synthesis of DNA is a critical part of the cell cycle and if this process is impeded, then there cannot be successful growth and division of cancer cells. Antimetabolites resemble the building blocks of DNA and RNA and if they incorporate into the new strand of DNA, then the cell will recognize this as a mistake and cell death occurs. They also work by blocking important enzymes necessary for DNA synthesis. By this means, cancer cells aren't able to replicate.
In order for your cells to grow, I mentioned that DNA needs to be replicated so that the new cells have the same DNA. DNA consists of two strands, and in order for them to be replicated, the two strands must be opened so that the information can be copied. DNA is coiled very tightly, and so when enzymes open the double strands, molecules called topoisomerases hold the strand apart so that they don't coil again. Topoisomerase inhibitors interfere with the functioning of topoisomerases, and thus if the DNA molecules aren't able to stay open or apart, then new DNA cannot be synthesized, and new cancer cells cannot be produced.
CYTOTOXIC OR ANTI-TUMOR ANTIBIOTICS
This treatment is derived from the soil fungus Streptomyces, and they work by varied mechanisms whereby they disrupt cell division, and thus prevent new growth of cancer cells. They are specific, and different types interrupt the cell cycles at different stages. The three most common cytotoxic antibiotics include anthracylines, chromocyclins and bleomycins.