中文摘要：

目的：探讨结直肠癌耐药细胞增殖及侵袭力与Na＋，F＋-ATP酶活性及其β1亚单位和P糖蛋白（p-gP）表达的关系，及哇巴因增加化疗敏感性的可能机制。方法：以人结直肠癌亲本细胞（sw480）和耐奥沙利铂细胞（Sw480／OxR）为研究对象，采用MTS法、Transwell小室、生化酶学、实时定量PCR（Realtimequantitative，RT—PCR）及流式细胞技术等方法比较SW480细胞与SW480／OxR细胞的增殖及侵袭力、Na＋，K＋-ATP酶活性及其β-亚单位和P—gp表达的差异，观察哇巴因对SW480／OxR细胞上述指标的影响。结果：与SW480细胞比较，SW480／OxR细胞增殖活力无明显变化（P〉0．05），而细胞侵袭力却显著增加，Na＋，K＋-ATP酶活性下降，β-亚单位表达下调，P—gp表达上调（P均〈0．01）；哇巴因能显著抑制SW480／OxR细胞增殖活力，减弱其侵袭力，下调SW480／OxR细胞P—gP蛋白表达，上调SW480／OxR细胞B。亚单位蛋白表达，增加SW480／OxR细胞Na＋，K＋-ATP酶活性（P均〈0．01）。结论：Na＋，K＋-ATP酶活性下降可能源于B。亚单位表达下调，并参与结直肠癌的耐药；哇巴因能部分逆转结直肠癌耐药细胞MDR，可能与增加Na＋，K＋-ATP酶活性及下调P—gp表达有关。

英文摘要：

Objective： This work aimed to explore the effects of Na＋/K＋-ATPase activity and the expression of its β1-subunit and P-glycoprotein （ P-gp ） on the proliferation and invasion of human colorectal cancer parental cells （ SW480 ） and oxaliplatin-resistant cells （ SW480/OxR ）. The molecular mechanisms of ouabain for reversing the multidrug resistance （ MDR ） of human colorectal cancer oxaliplatin-resistant cells were also examined. Methods： SW480 and SW480/OxR cells derived from the same patient were treated with or without ouabain at the physiological concentration of 1 nM. The SW480 and SW480/OxR cell proliferation capacity was assessed by the MTS assay. The invasion capacity was deteremined using a Transwell chamber. The Na＋/K＋-ATPase activity was mea- sured by biochemical and enzymological techniques. The expression of the β1-subunit and P-gp of Na＋/K＋-ATPase was determined by real-time quantitative PCR, Western blotting, and flow cytometry. Results： The capacity of invasion significantly increased in the SW480/OxR cells compared with the SW480 cells （ P 〈 0.01 ）. There was no difference between the SW480 and SW480/OxR cell pro- liferation capacities （ P 〉 0.05 ）. The Na＋/K＋-ATPase activity significantly decreased in SW480/OxR cells compared with SW480 cells （ P 〈 0.01 ）. The expression of the Na＋/K＋-ATPase β 1-subunit in mRNA and protein levels was lower in SW480/OxR cells than in SW480 cells （ P 〈 0.01 ）. However, the expression of P-gp in mRNA and protein levels was higher in SW480/OxR cells than in SW480 cells （ P 〈 0.01 ）. Interestingly, ouabain at the physiological concentration of 1 nM significantly enhanced the activity of Na＋/K＋-ATPase in SW480/OxR cells （ P 〈 0.05 ）. The expression of the β1-subunit was also upregulated and that of P-gp was downregulated at the protein level, thereby inducing a decrease in the capacity of SW480/OxR cell growth inhibition and invasion. Nevertheless, after ouabain treatment for 48 h, the