There are many types of chemotherapy drugs physicians use to treat cancer patients and they vary in how they attack and destroy cancer cells. Some types of chemotherapy are more effective with certain types of cancers, and some work best in tandem with other drugs. Chemotherapy treatment is very complex and triggers a cascade of reactions within the body.
Sometimes, patients become resistant to chemotherapy and it becomes much less effective. Oncologists have found this particularly prevalent in patients who receive multiple chemotherapy treatments. So, one active avenue of cancer research is finding ways to overcome this challenge.
Scientists have found that certain proteins seem to predict resistance to chemotherapy, including Paclitaxel, a new class of anticancer drugs often used with patients who have ovarian, breast, lung, head, or neck cancers, and non-small cell lung cancer. Paclitaxel can be administered alone or in combination with other drugs.
A new study identifies a specific protein, called Abcc10, which resists chemotherapy drugs, specifically those that work to interrupt the growth and spread of cancer cells by disrupting cell division, like Paclitaxel.
In this newest study, researchers found that mice without the Abcc10 protein were much more sensitive to drugs. This is important because if drugs are developed that inhibit the action of Abbc10, it may increase the effectiveness of chemotherapy.
Abcc10 is part of a family of transporter proteins, which include multi-drug resistant (MDR) proteins. Transporters act like little pumps that force chemotherapy out of cells, reducing the concentration of anticancer drugs and thus reducing their intentional toxic effect. These transporter proteins are actually a built in mechanism to protect our body against powerful drugs like chemotherapy.
Scientists have also identified two drugs (Imatinib and Nilotinib) that seem to reverse the resistance of cancer cells with MDR proteins. Imatinib and Nilotinib are called Tyrosine Kinase Inhibitors. Tyrosine Kinases are enzymes that function as on-off switches in many cellular functions. So, in effect, by disabling the on-off switch and preventing cells from pumping drugs out of cells, it should improve the effectiveness of chemotherapy.
Although this line of research is still relatively new, scientists are making progress towards understanding how to extend the effectiveness of chemotherapy in patients who stop responding to treatment.
Sources:
Fox Chase Cancer Center. "New Findings Show that the Protein Abcc10 May be Effective in Counteracting Resistance and Extending the Effectiveness of Some Anticancer Drugs." Press release. Web. 16 May 2011.
http://www.fccc.edu/news/2011/2011-05-16-hopper.html
Shen,Tong, Kuang, Ye-Hong, Ashby, Charles, R. Jr, Lei, Yu, Chen, Angel, Zhou, Ying, Chen, Xiang, Tiwari, Amit K., Hopper-Borge, Elizabeth, Ouyang, Jiangyong, and Chen, Zhe-Sheng. "Imatinib and Nilotinib Reverse Multidrug Resistance in Cancer Cells by Inhibiting the Efflux Activity of the MRP7 (ABCC10)." PLoS One 4(10) (2009): e7520. Web. 20 October 2009.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2759525/
U.S. National Library of Medicine. Medline Plus. "Paclitaxel Injection." Web. 2 January 2011.
http://www.nlm.nih.gov/medlineplus/druginfo/meds/a607070.html
National Cancer Institute. "Paclitaxel." Web. 2 July 2010.
http://www.cancer.gov/cancertopics/druginfo/paclitaxel
