Klin Onkol 2000; 13(Speciál2 2000): 4-9.
Summary: Surgery, radiotherapy and chemotherapy are 3 most effective ways to treat malignant diseases today. One of the most serious complications and also reason of chemotherapy failure is an ability of tumor cells to resist cytotoxic agents. This paper reviews drug resistance issue of malignant cells and is focused on multidrug resistance (MDR). Criteria are given to divide MDR to 2 groups: typical (classical) MDR and atypical MDR. Classical MDR is caused by membrane P-glycoprotein (Pgp). This 170 kDa protein belongs to a superfamily of ABC-transport proteins. Pgp molecule is described here as for its structure, functions, and natural expression in human tissues. Hypothesis trying to explain its broad specificity are given as well as its presence in organisms ranging from bacteria to man. Studies dealing with significance of Pgp for clinical MDR in hematological malignancies and solid tumors are also reported.
