摘要：
ObjectiveTo investigate the potential and mechanism of rAd/p53 in the reversal resistance to 5-fu in human colon cancerin vivo.Methods Nude mice with human colon cancer SW480/5-FU (5-FU resistance) were randomly assigned into four groups (25 per group): control group, 5-FU group, rAd/p53 group, rAd/p53+5-FU. At 24 h, 48 h, 72 h, 120 h and 168 h after treatment, 5 mice were selected randomly from each group and sacrificed with an overdose of anesthetic. Their tumors were removed and detected the protein expression of p53, PKC, P-gp and MPR1 (Western blot) and apoptosis (TUNNEL). Repeat analysis of variance, SNK test and Pearson's correlation were used for statistical analysis.Results There were no significant differences of tumor cell apoptosis and the protein expression of p53, PKC, P-gp and MPR1 between 5-FU group and control group at the observed time point (P>0.05). The area ratios of tumor cell apoptosis in the rAd/p53+5-FU group (0.33±0.03 to 0.62±0.07) were significant larger than that of control group (0.24±0.04 to 0.29±0.02), 5-FU group (0.27±0.03 to 0.31±0.02) and rAd/p53 group (0.29±0.02 to 0.46±0.06) (P<0.05). The area ratios of tumor cell apoptosis in the rAd/p53 group were significant larger than that of control group (P<0.05). More than 48 h after treatment, the area ratios of tumor cell apoptosis in the rAd/p53 group were significant larger than that of 5-FU group (P<0.05). The p53 expression in the rAd/p53 and the rAd/p53+5-FU group was more than that of control group at the observed time point (P<0.05) and increased with time increasing, the peak expression appeared at 120 h. The p53 expression in rAd/p53+5-FU group were significantly higher that of rAd/p53 group (P<0.05). The expression of PKC, P-gp and MRP1 in the rAd/p53+5-FU group gradually decreased and the expression of P-gp and MRP1 were significantly lower that of control group and 5-FU group at the observed time point. More than 48 h after treatment, the expression of PKC in the rAd/p53+5-FU group were significantly lower that of control group, 5-FU group and rAd/p53 group. In rAd/p53 group, the expression of P-gp and MRP1 were significantly lower that of control group and 5-FU group more than 48 h, the expression of PKC were significantly lower that of control group and 5-FU group more than 120 h. ConclusionsExogenous wild-type p53 gene from rAd/p53 can decrease expression of PKC, P-gp, MRP1 in SW480/5-FU (5-FU resistance) and promote apoptosis of tumor cell, which contribute to reverse 5-FU resistance. 5-FU can increase the expression of exogenous wild-type p53, so 5-FU combined with rAd/p53 has a synergisticanticancer effect.%目的：活体探讨腺病毒介导的 p53逆转结肠癌对5-氟尿嘧啶（5-FU）耐药的可能性及其机制。方法对5-FU耐药的人类结肠癌SW480/5-FU荷瘤裸鼠随机分成4组：对照组、5-FU治疗组、rAd/p53治疗组和rAd/p53＋5-FU治疗组，各25只。各组于治疗后24 h、48 h、72 h、120 h、168 h分别随机取5只荷瘤鼠，腹腔注射过量水合氯醛处死，即切下肿瘤检测肿瘤组织的癌细胞凋亡和肿瘤的p53、PKC、P-gp、MRP1蛋白表达。用方差分析与SNK检验比较各组的癌细胞凋亡、各蛋白表达量，用Pearson相关检验分析各观察指标的相关性。结果5-FU组不同时间点裸鼠肿瘤细胞凋亡范围、p53蛋白表达、PKC、P-gp、MRP1蛋白表达与对照组差别没统计意义（P＞0.05）。rAd/p53＋5-FU 组细胞凋亡（0.33±0.03～0.62±0.07）明显高于对照组（0.24±0.04～0.29±0.02）、5-FU组（0.27±0.03～0.31±0.02）与rAd/p53组（0.29±0.02～0.46±0.06）（P＜0.05）；rAd/p53组肿瘤凋亡范围明显高于对照组（P＜0.05），48 h以后明显高于5-FU组（P＜0.05）。rAd/p53和rAd/p53＋5-FU组随时间增加p53蛋白表达明显逐渐增加，120 h达峰值表达，明显高于对照组（P＜0.05），Ad/p53＋5-FU组p53蛋白表达明显高于rAd/p53（P＜0.05）。rAd/p53＋5-FU组在不同观察时间点PKC、P-gp、MRP1蛋白表达量呈逐渐降低趋势，P-gp、MRP1的表达在各时间点明显低于对照组、5-FU组（P＜0.05）；48 h后PKC表达明显低于对照组、5-FU组、rAd/p53组（P＜0.05）。 rAd/p53组治疗48 h后，P-gp、MRP1的表达量明显低于对照组、5-FU组（P＜0.05）；120 h后PKC表达明显低于对照组、5-FU组（P＜0.05）。结论 rAd/p53携带的外源野生型p53基因能降低活体耐药的结肠癌细胞的PKC、P-gp、MRP1等耐药基因蛋白表达，同时促进癌细胞凋亡而逆转癌细胞对5-FU的抗性；5-FU也可增加外源野生型p53的表达产生两者的协同抗癌作用。
