ABSTRACT
This study was aimed to investigate the relevance of nilotinib in combination with tetrandrine (Tet) on reversing multidrug resistance and inducing apoptosis of K562/A02 cell line and its mechanism. Methyl-thiazol tetrazolium (MTT) assay was employed to examine the pharmacological effect of nilotinib or Tet alone on K562/A02 cell line, the IC(50) of daunorubicin (DNR) on K562/A02 cell line treated with nilotinib and Tet was calculated; the flow cytometry (FCM) was employed to detect the apoptosis rate of K562/A02. The expression of bax/survivin mRNA was determined by RT-PCR, and the expression of bax/survivin protein was assayed by Western blot. The results showed that after being treated by 5 nmol/L nilotinib or 1.0 µml/L Tet for 48 hours, IC(50) of DNR to K562/A02 was 5.71 ± 0.72 mg/L or 6.52 ± 0.43 mg/L, respectively, while in their combined treatment, IC(50) decreased to 3.12 ± 0.13 mg/L. Nilotinib or Tet alone could increase DNR-inducing apoptosis rate of K562/A02 cell, while the apoptosis rate of K562/A02 increased remarkably in combination treatment of nilotinib with Tet. After being treated with 5 nmol/L nilotinib or 1.0 µml/L Tet alone for 48 hours, the expressions of bax mRNA and BAX protein was up-regulated, while both effects were more obvious in combination treatment of nilotinib with Tet. Treatment with 5 nmol/L nilotinib or 1.0 µmol/L Tet alone for 48 hours down-regulated the expression of survivin mRNA and its protein, while treatment of nilotinib in combination with Tet had more significant effect on down-regulation of their expression. It is concluded that the K562/A02 cells are resistant to DNR, nilotinib or Tet alone both can partially reverse resistance of K562/A02 cells to DNR, increase the apoptosis rate of K562/A02 cells. Combination of nilotinib with Tet shows obvious synergistic action, mechanism of which may associate with up-regulation of bax mRNA and BAX protein expressions and down-regulation of survivin mRNA and its protein expressions.
Subject(s)
Humans , Apoptosis , Benzylisoquinolines , Pharmacology , Daunorubicin , Pharmacology , Drug Resistance, Multiple , Drug Resistance, Neoplasm , Gene Expression Regulation, Leukemic , Inhibitor of Apoptosis Proteins , Genetics , K562 Cells , Pyrimidines , Pharmacology , bcl-2-Associated X Protein , GeneticsABSTRACT
<p><b>OBJECTIVE</b>To investigate the reversible effect of nilotinib, BrTet (5-bromotetrandrine) and their combination on multidrug resistance cell line K562/A02 and its mechanism.</p><p><b>METHODS</b>Cell proliferation inhibition was assessed by MTT method and cell apoptosis by flow cytometry (FCM). The expression of mdr1 mRNA was determined by RT-PCR, and the expression of P-gp was assessed by Western blot.</p><p><b>RESULTS</b>After 48 h 5 nmol/L nilotinib or 0.5 µmol/L BrTet treatment, IC(50) of daunorubicin (DNR) to K562/A02 was 4.52 mg/L or 5.41 mg/L respectively; While on combinative treatment, its IC(50) decreased to 2.98 mg/L. Nilotinib or BrTet alone was not able to increase the DNR induced apoptosis rate of K562/A02 cell (P > 0.05), while on combination treatment the apoptosis rate increased remarkably. After 48 h 5 nmol/L nilotinib or 0.5 µmol/L BrTet treatment alone, gray-scale value of mdr1 mRNA was 0.48 ± 0.04 or 0.64 ± 0.01, respectively; while on combinative treatment the value decreased to 0.35 ± 0.04. The P-gp expression level in K562/A02 cells was 0.61 ± 0.05, or 0.52 ± 0.02 when treated with 5 nmol/L nilotinib or 0.5 µmol/L BrTet alone for 48 h, but on combination treatment, the level decreased to 0.44 ± 0.03.</p><p><b>CONCLUSION</b>Nilotinib or BrTet alone can partially reverse drug resistance of K562/A02 cells. The mechanism may be associated with the decrease of mdr1 mRNA and P-gp expression and increase of the apoptosis rate. And there is a synergistic action with these two agants in combination.</p>
Subject(s)
Humans , ATP Binding Cassette Transporter, Subfamily B, Member 1 , Metabolism , Daunorubicin , Pharmacology , Drug Resistance, Multiple , Drug Resistance, Neoplasm , K562 CellsABSTRACT
This study was aimed to explore the effects and mechanisms of transplantation tolerance induced by "TBI + cyclophosphamide (CTX)" regimen combined with intra-bone marrow injection of allogenic BMCs. On day 0 C57BL/6 (H-2(b), B6) mice received sublethal dose of total body irradiation (TBI) ((60)Co gamma-ray) followed by intrabone marrow-bone marrow transplantation (IBM-BMT) of 3 x 10(7) cells/30 microl BMCs from BALB/c (H-2(d)) mice. The recipient mice were given CTX intraperitoneally 2 days after IBM-BMT. On day 7 skin grafting was performed and the skin survival was observed. The tolerance mechanism was investigated by mixed lymphocyte reaction (MLR), IL-2 reverse test, adoptive transfer assay in vitro. The results showed that the mean survival time (MST) of skin allografts in group treated with TBI + CTX + BMT was significantly longer, compared with that of other groups (P < 0.01). On day 90 after IBM-BMT, the phenotypic character of the recipient mice (black color) began to convert to that of the donor mice (white color). The MLR demonstrated that the immune responses of recipient mice were donor-specific tolerance. Suppressive activity in the spleen cells of tolerant B6 mice was observed in adoptive transfer assay in vitro. IL-2 reversal and the phenotypic conversion showed that the tolerance mechanisms were involved in clonal anergy and the development of chimerism. It is concluded that the nonmyeloablative regimen combined with IBM-BMT can induce a long-term tolerance, and the multiple mechanisms including clonal anergy, suppressor cells and chimerism were involved in transplantation immune tolerance.