How Does Chemotherapy Resistance Happen

Cancer in itself is a very dangerous and life threatening disease. Where chemotherapy is supposedly a messiah in the land of the hopeless, the hopeless often returns with renewed interest in destroying life. One of the greatest obstacles to chemotherapy is drug resistant behavior of the cancer cells. This occurs when the cancer cells somehow obstruct the entry of chemotherapy drugs. The problem is that if this kind of cell mutates, it may produce many others like itself. [Read: How is Chemotherapy Given?]

This interesting phenomenon happens when the cancer cells emit a substance called p-glycoprotein. This substance can actually remove the chemotherapy drug from the cancer cell and this process repeats many times. The resistant nature of cancer cells is not restricted to just one or two types of cancer cells, but many others. The types of drugs that can be resisted by cancer cells are paclitaxel, docetaxel, vinorelbine, vincristine, vinblastine, doxorubicin, daunorubicin, epirubicin, etoposide, teniposide, topotecan, dactinomycin and mitomycin C. Moreover, these are common drugs used to treat a variety of cancers ranging from big tumors to lymphoma. Cancer cells at times may stop taking these drugs or pump them out. This is because of the substance p-glycoprotein and the inability of the protein, which transports the drug across the cell wall, to work.[Read: How Does Chemotherapy Work?]

These resistant cells as found by a study contain amplified MDR1 genes resulting in an increased expression of genes. This MDR1 gene encodes in them p-glycoprotein. The other mechanism that causes this is the release of a gene known as the multi-drug resistant associated protein. Both these genes have been identified as members of a super family that are ATP depended transporters. There are many other genes probably out there that are members of this super family yet to be identified.

Doctors, several times, try to fight the cells’ brash behavior by giving a combination of chemotherapy drugs. This is done with the hope of catching the resistant cells off guard so that the cancer cell will fail to resist at least one type of drug. It is important for the doctor to identify the correct combination to make sure that the cells do not become resistant to the others. The moment this happens, another possibility is lost. [Read: Types of Chemotherapy Treatments]

In the world of patients whose chemotherapy drugs are failing every day, hope has yet again been replaced by hopeless. Let us wait for Science to save the day.