氟哌啶醇在K562/Dox细胞中对P-糖蛋白及氯离子通道的影响

目的　探讨氟哌啶醇 (Hal)对人红白血病耐药细胞K5 6 2 /Dox的逆转耐药作用 ,以及对P 糖蛋白 (P gp)和肿胀激活的氯离子通道的影响。方法　应用乳酸脱氢酶法 (LDH) ,测定Hal对瘤细胞增殖的抑制作用。以半定量逆转录聚合酶链反应 (RT PCR) ,分析经Hal处理后 3种耐药基因mRNA表达的变化。将瘤细胞荷载氯离子敏感染料MQAE后 ,以荧光分光光度计测定低渗环境中Hal对K5 6 2 /Dox细胞肿胀激活的氯离子通道的影响 ;应用ZM库尔特血球计数仪及 2 5 6频道测定仪 ,测定低渗环境中瘤细胞的体积变化 ,以判断Hal对细胞调节性体积减小 (RVD)的影响。结果　Hal对K5 6 2 /Dox细胞的耐药性具有明显的逆转作用 ,在 12 .5 0 ,6 .2 5和 3.12 μmol/L浓度时 ,其对K5 6 2 /Dox细胞耐药性的逆转倍数分别为 8.6 1,4 .35和 2 .2 5。RT PCR结果显示 ,用 12 .5 0 μmol/LHal处理K5 6 2 /Dox细胞后 ,P gp和多药耐药相关蛋白 (MRP)mRNA表达水平均降低 ,并呈现时间依赖性 ,分别较原水平下降 76 .3%和 6 4 .6 % (P <0 .0 5 ) ;谷胱甘肽硫转移酶π(GSTπ)mRNA的表达水平于用药后第 2天下降6 6 .1% ,第 3天回升 (P <0 .0 5 )。K5 6 2 /Dox细胞的氯离子浓度检测结果显示 ,单纯低渗刺激可使K5 6 2 /Dox细胞中MQAE荧光强度下降 (34.4 6± 5 .91

Reversal effect of haloperidol on doxorubicin resistance and chloride channel inhibition in erythroleukemic cell K562/Dox

OBJECTIVE: To investigate the reversal effect of haloperidol (Hal) on doxorubicin (Dox) resistance and its inhibition effect on P-glycoprotein and swelling-activated chloride channel in Dox-resistant erythro-leukemic cell line K562/Dox. METHODS: Tumor cell proliferation was measured by LDH assay. mRNA expressions of P-glycoprotein (MDR1), glutathione S-transferase Pi (GSTpi) and MDR-associated protein (MRP) of K562/Dox treated with Hal were assayed by RT-PCR. Chloride-sensitive dye MQAE was loaded into K562/Dox cells and the intracellular fluorescence intensity was measured to evaluate the effect of Hal on chloride channel in swelling-activated K562/Dox cells. Coulter counter ZM and Channelyzer 256 were used to measure cell volume regulation. RESULTS: Hal significantly reversed Dox resistance in K562/Dox cells after 12.50, 6.25 and 3.12 micromol/L Hal treatment, the chemosensitivity to Dox increased by 8.61, 4.35 and 2.25 times respectively. After treatment with Hal 12.50 micromol/L, MDR1 and MRP mRNA expression were gradually down-regulated in a time-dependent manner on d1-d3, reducing to 76.3% and 64.6% of the control level on d3 (P < 0.05), while GSTpi mRNA expression decreased by 66.1% (P < 0.05) on d1-d2, and began to recover on d3. The swelling-activated chloride channel and cell regulatory volume decreased (RVD) in K562/Dox cells were also inhibited by Hal. Under hypotonic challenge the cellular fluorescence intensity which represented chloride concentration declined by (34.46 +/- 5.91)%. After adding 6.25 micromol/L and 18.75 micromol/L Hal, the hypotonic challenge only caused decrease in fluorescence intensity by (24.43 +/- 3.25)% and (16.63 +/- 4.98)% (P < 0.01). RVD in hypotonic condition was (84.95 +/- 5.69)%. RVD under hypotonic condition with 6.25 micromol/L and 18.75 micromol/L Hal were (51.12 +/- 6.01)% and (39.51 +/- 4.79)% respectively (P < 0.01). CONCLUSION: A nontoxic concentration of haloperidol can significantly reverse drug resistance through a multi-pathway effect, including down-regulating mRNA expressions of MDR, GSTpi and MRP, inhibition of swelling-activated chloride channel and RVD in K562/Dox cells.