[Show abstract][Hide abstract]ABSTRACT: The present study was undertaken to estimate the therapeutic benefit to down-regulate the Na(+)/H(+) exchanger 1 (NHE1) for reversing chemoresistance of BCR-ABL-positive leukemia patient cells and cell lines. As a result, after treatment with specific NHE1 inhibitor Cariporide or high K(+) buffer to decrease intracellular pH (pH(i)), cells from relapsed patients exhibited decreased Pgp level, enhanced Rhodamine123 and drug accumulation, decreased colony-forming ability and the modulations of mitogen-activated protein kinases (MAPKs) activities. Furthermore, we used BCR-ABL-positive cell line K562 and its resistant counterparts K562/DOX and K562/G01 cell lines for further study. Together, these findings suggest that Pgp may be associated with the reversal of drug resistance in BCR-ABL-positive leukemia patients and cell lines by the inhibition of NHE1 though MAPK pathways.
[Show abstract][Hide abstract]ABSTRACT: Multidrug resistance (MDR) induced by drug efflux has been identified as the major clinical obstacle in the treatment of childhood acute lymphoblastic leukemia (ALL). To explore the possible effects of midkine (MK) gene on the chemotherapeutic drugs efflux, we examined the MK gene expression in 139 B-lineage ALL patients and 15 children with nonmalignant hematological diseases. Meanwhile, we detected the degree of drug accumulation in 30 progressing B-lineage ALL patients and the 15 control individuals (as control). The results showed that the significant statistic difference in MK gene expression was found among the normal group, the complete remission (CR), and progressing B-lineage ALL patients (p < 0.01). In the Rhodamine 123 (Rh123) efflux test, mean fluorescence intensity (MFI) in the leukemia cells was obviously lower than that in normal pre-B cells (p < 0.01). Furthermore, there was an evident negative correlation between the MFI and MK mRNA expression (r = -0.869, p < 0.001) but no correlation with the MDR1 mRNA expression (p > 0.05). We concluded that there was powerful drug efflux ability in lymphoblastic leukemia cells with high MK gene expression. MK gene may take part in multidrug resistance.
Full-text · Article · Jul 2010 · International journal of hematology