Lekooporność nowotworów - problem nie tylko u ludzi

Chemoresistance is the main problem in human and veterinary oncology. The most important mechanism of chemoresistance is the expression of efflux pumps from the ABC superfamily, which remove drugs from cancer cells, thus rendering the treatment ineffective. The most important efflux pumps are P-glycoprotein (PGP), multidrug resistance protein 1 (MRP1), multidrug resistance protein 3 (MRP3), and breast cancer resistance protein (BCRP). In humans the expression of efflux pumps, their mechanism of action, and substrates are well described. Little is known, however, about chemoresistance in veterinary medicine. Only a few experiments have been performed, using canine mammary tumors, but the expression of efflux pumps and their substrates are still insufficiently researched. Moreover, preliminary data suggest great differences between various species. This fact underlines the need for a thorough examination of efflux pump substrates in animals because veterinary patients are usually treated according to human chemotherapy protocols.