Apc⁃Kras⁃Cre肠腺瘤转基因小鼠模型构建

Establishment of intestinal polyp animal model with Apc⁃Kras⁃Cre genetic mutation

目的探讨构建Apc⁃Kras⁃Cre肠腺瘤小鼠模型最佳他莫昔芬诱导方式,建立小鼠模型。方法以C57BL/6J野生型小鼠为健康的对照组。以不同浓度、剂量、给药时长他莫昔芬腹腔注射于转基因小鼠,即组1以低剂量他莫昔芬(5 mg/kg)给药1 d,组2以低剂量他莫昔芬(5 mg/kg)给药3 d,组3以高剂量他莫昔芬(50 mg/kg)给药1 d,组4以高剂量他莫昔芬(50 mg/kg)给药3 d,给药4周后观察各组小鼠生存率、体重变化,药物诱导4周后观察各组小鼠肠道长度变化、肠内腺瘤生长数量以及大小,再通过苏木精伊红染色、显微镜下观察肠道组织、腺瘤的生理情况。结果第一部分实验发现雌鼠生存率低于雄鼠(P<0.001),死亡率高于雄鼠(P<0.05),各组不同浓度与剂量之间比较生存率差异具有统计学意义(P<0.01)。各组小鼠体重变化与对照组相比差异具有统计学意义(P<0.001),组1与组2,组2与组3,组1与组4之间差异各具统计学意义(P<0.001,P<0.01,P<0.05)。各组小鼠大肠长度与对照组相比未具统计学意义(P>0.05),组1与组3差异具有统计学意义(P<0.05)。各组小鼠大肠内都长有腺瘤,多数于结肠远端,组3与组4腺瘤较多也较大。给药组小鼠大肠病理情况与健康对照组相比出现腺瘤生长,腺体组织排列紊乱、上皮细胞排列不齐,肠道黏膜屏障松散,隐窝分歧不规则,组3、组4也有炎症发生,组4部分区域发现细胞坏死。结论他莫昔芬诱导Apc⁃Kras⁃Cre肠腺瘤转基因小鼠造模成功,并且由此判断,他莫昔芬浓度10 mg/mL、5 mg/kg的剂量诱导1 d的诱导方式最为合适。

Objective To create a mouse model of colorectal polyps with Apc⁃Kras⁃Cre gene mutations using the tamoxifen induction method.Methods Mice with Apc⁃Kras⁃Cre mutations were divided into four groups and injected intraperitoneally with different concentrations and dosages of tamoxifen for different durations,with group 1 injected with low dosage tamoxifen(5 mg/kg)for 1 day,group 2 injected with low dosage tamoxifen(5 mg/kg)for 3 days,group 3 injected with high dosage tamoxifen(50 mg/kg)for 1 day,group 4 injected with high dosage tamoxifen(50 mg/kg)for 3 days.C57BL/6J mice were used as a healthy control group and survival and changes in body weight were observed.All mice were euthanized 4 weeks post⁃tamoxifen induction and the colon length and number and size of intestinal polyps were observed.Histological changes in the intestinal tissue and polyps were detected by hematoxylin and eosin staining.Results The survival rate of male mice was higher(P<0.001)and the morbidity rate of male mice was lower compared with female mice(P<0.05).The survival rate differed significantly among the four groups(P<0.01).All groups showed significant changes in body weight compared with the healthy control group(P<0.001).There were also significant differences in weight changes between tamoxifen⁃induced groups 1 and 2,between groups 2 and 3,and between groups 1 and 4(P<0.001,P<0.01,P<0.05,respectively).There were no significant differences in colon length between any treated group and the healthy control group(P>0.05),but colon length did differ between tamoxifen⁃induced groups 1 and 3(P<0.05).Polyp size varied in each group of tamoxifen⁃treated mice,with most polyps occuring at the distal end of the colon,while mice in groups 3 and 4 had more and larger polyps.Histopathological examination showed intestinal polyps with uneven and misaligned glandular and epithelial arrangements,a loosely⁃packed intestinal mucosal barrier,and irregularly⁃distributed crypts in tamoxifen⁃induced mice compared with the healthy control group,while mice in tamoxifen⁃induced groups 3 and 4 showed signs of inflammation and mice in group 4 showed necrosis of cells in some regions.Conclusions Tamoxifen⁃induced Apc⁃Kras⁃Cre model mice were successfully established,with the group 3 induction method being the most suitable.