Establishment and characterization of arsenic trioxide resistant KB/ATO cells

Arsenic trioxide (ATO) is used as a chemotherapeutic agent for the treatment of acute promyelocytic leukemia. However, increasing drug resistance is reducing its efficacy. Therefore, a better understanding of ATO resistance mechanism is required. In this study, we established an ATO-resistant human epidermoid carcinoma cell line, KB/ATO, from its parental KB-3-1 cells. In addition to ATO, KB/ATO cells also exhibited cross-resistance to other anticancer drugs such as cisplatin, antimony potassium tartrate, and 6-mercaptopurine. The arsenic accumulation in KB/ATO cells was significantly lower than that in KB-3-1 cells. Further analysis indicated that neither application of P-glycoprotein inhibitor, breast cancer resistant protein (BCRP) inhibitor, or multidrug resistance protein 1 (MRP1) inhibitor could eliminate ATO resistance. We found that the expression level of ABCB6 was increased in KB/ATO cells. In conclusion, ABCB6 could be an important factor for ATO resistance in KB/ATO cells. The ABCB6 level may serve as a predictive biomarker for the effectiveness of ATO therapy.

Construction of wild-type and mutant ABCB6-DsRed fusion protein expression vectors / 医学研究生学报

Objective The mutation of the ABCB6 gene is involved in a variety of diseases , including dyschromatosis univer-salis hereditaria (DUH).This study aimed to construct the expression vectors for the ABCB 6-DsRed fusion proteins, pDsRed-wt-AB-CB6 and pDsRed-L356P-ABCB6, detect its cellular localization in A375 cells, and thus facilitate future studies on the pathogenesis of ABCB6-related diseases . Methods The recombinant plasmids pDsRed-wt/L356 P-ABCB6 were constructed based on the previously constructed pIRES2-ZsGreen1-ABCB6 vector and then transfected into A 375 cells.At 48 hours after transfection , the expression of AB-CB6 was detected by Western blot and the cellular localization of ABCB 6 determined under the laser scanning confocal microscope . Results The expression vectors pDsRed-wt/L356P-ABCB6 were verified by colony PCR, enzyme digestion, and DNA sequencing. The expression of ABCB 6 was significantly increased in the A 375 cells after transfected with the recombinant plasmids .Confocal mi-croscopy showed the localization of both wild-type and mutant ABCB6 in the cytoplasm. Conclusion The expression vectors for wild-type and mutant ABCB6-DsRed fusion protein were successfully constructed and the localization of ABCB 6 in A375 cells was de-termined, which may serve as a basis for further studies of ABCB 6 and the pathogenesis of ABCB 6-related diseases .