Abstract:

Abstract:Objective  To investigate the reversal effects of tetramethylpyrazine (TMP) and cyclosporin A(CsA) on multidrug resistance(MDR) of human erythroleukemia cells with gene transfer K562/MDR and to discuss the possible correlative mechanism. Methods K562/MDR cells in culture medium were      treated with TMP （50—6 400  mg·L^-1）　and CsA（0.5—256  mg·L^-1 ） respectively. The growth rates of these cells were measured by MTT assay.Non-cytotoxic doses of TMP and CsA were determined.There were 5 growps in the experiment:G1（TMP+ADM+K562/MDR）,G2（CsA+ADM+K562/MDR）,G3（TMP+CsA+ADM+K562/MDR）,negative control （K562/MDR subsitituted by K562/S）,control（drugs subsitituted by 1640 culture medium）,the inhibitory effects of adriamycin (ADM) used alone or in combination with TMP or/and CsA on the proliferation of K562/S and K562/MDR cells were observed by resisting fold and reversal folds.The effects of TMP and CsA on ADM accumulation in K562/S and K562/MDR cells were analyzed by fluorospectrophotometry.The protein level of P-glycoprotein (P-gp) was detected by flow cytometry (FCM).
Results The non-cytotoxic doses of TMP and CsA were 320 and 2.0 mg·L^-1,respectively.The resistance of K562/MDR cells to ADM was 19.2 folds of that of K562/S cells.When TMP and CsA were added along with ADM to the K562/MDR culture,the reversal folds were 5.2 and 9.6.When TMP in combination with CsA was added along with ADM to the K562/MDR culture,the reversal folds were 15.6.When various concentrations ADM were added to the K562/MDR culture,TMP and CsA could increase the intracellular accumulation of ADM.The effect of TMP in combination with CsA was more evident.Compared with  control,TMP and CsA could inhibit the overexpression of P-gp protein（P<0.01）.Conclusion The single or combinated application of TMP and CsA could increase the drug concentration of K562/MDR cells and reverse the MDR of tumor cells.Its activity may be related to the inhibition of P-gp protein overexpression.
Key words：tetramethylpyrazine;cyclosporin A;multidrug resistance reverse;K562/MDR cells

Key words: tetramethylpyrazine;cyclosporin A;multidrug resistance reverse;K562/MDR cells