A Vitro Study Of The Relationship Between NF κB And The Effects Of Iron-deprivation On The Expression Of Multidrug Resistance Gene Of Leukemia Cells

Background and Purpose: Multidrug Resistance (MDR) of leukemic cells is one of the major factors leading to therapy failure and relapse of leukemia. The study of the mechanism of MDR and how to reversing or decreasing MDR has been a focus of attention in the field of leukemia. The overexpression of multidrug resistance gene 1 (MDR1) and P-glycoprotein (P-gp/P170) is the main mechanism of MDR. Most of tumor cells ,including acute or chronic leukemic cells, express abnormal Nuclear factor κB (NF-κB) .Many factors (such as cytotoxicity substances, chemotherapeutic drugs, ionic radiation, et al. ) which can induce the expression of MDR1, at the same times,can activate NF- κB. However, up to now, the relationship of NF-κB and MDR1 has not been clear. Iron is oneof the important elements of all live cells. It has been comfirmed that there have disorders of iron metabolism in the patients with malignant tumor diseases. The expressions of ferritin and transferritin receptor in leukemic cells are higher than in normal hemacytes. In the experiment, we study the roles that chemotherapeutic drugs play in the development of MDR of leukemia cells and the possible mechanism of them by using K562 cell as the research object and examing the expression of MDR1, Pgp/P170 and NF- k B. The purpose of this research is to provide experiment evidence for resolving MDR of leukemia in clinic.Methods: In the experiment, we used K562 cell as the study object. The research could be divided into three parts: 1, RT-PCR and flowcytometry were respectively used to detect the expression of MDRlmRNA and P-gp of K562 cells which were incubated with different concentration of daunorubicin for different time. 2, RT-PCR , flowcytometry and immunochemistry were respectively used to detect the expression of MDRlmRNA , P-gp and NF- k B of K562 cells which incubated with daunorubicin(DNR) for different time. 3^ To detect the effect of desferrioxamine(DFO) or ferric chloride (FeCl:i) combined with DNR on the expression of MDRlmRNA and P~gp and the activation of NF- k B in K562 cells, the same methods has been used .Results: K DNR upregulated the expression of MDRlmRNA and P-gp of K562 cells in a dose-time-dependent mode. 2> DNR activated NF-kB of K562 cells in a time-dependent mode. 3^ Compared with the control, the expression of MDRlmRNA was upregulatedimmediately after the activation of NF- k B. The expression of MDRlmRNA and the activation of NF- k B increased in the same mode. A^ Compared with the DNR group, iron-deprivation decreased the DNR-induced activation of NF- k B, but FeCl3 increased the DNR-induced activation of NF- k B. 5s Compared with the DNR group, iron-deprivation decreased the expression of MDRlmRNA and P-gp induced by DNR, but Fed., play the reverse role.Conclusion: K DNR can upregulate the expression of MDRlmRNA and P-gp in K562 cells in a dose - time-dependent mode, the mechanism of which may be related to the activation of NF- k B. 2> iron-deprivation can inhibit the upregulation of expression of MDRlmRNA and P-gp induced by DNR in K562 cells, the mechanism of which may be that iron-deprivation decreased the activation of NF-k B induced by DNR through its antioxidation, and then inhibited the expression of MDRlmRNA and P-gp.