芥菜籽预防化学诱导小鼠大肠肿瘤的实验研究

The experimental study on chemopreventive effect of mustard seed on chemically induced colorectal tumor in mice

目的评价芥菜籽(MS)对氧化偶氮甲烷(AOM)诱导的小鼠大肠肿瘤的预防作用及其机制。方法选择60只昆明种小鼠,随机均分为AOM模型组、AOM+5%MS干预组、AOM+10%MS干预组和正常对照组(生理盐水)。记录各组小鼠有无肿瘤发生及发生数目、大小和位置,计算平均肿瘤数和肿瘤发生率;HE染色确定肿瘤的组织学类型;免疫组化染色检测肿瘤组织中PCNA蛋白的表达,计算增殖指数(PI);TUNEL染色检测肿瘤组织凋亡情况,计算凋亡指数(AI)。结果正常对照组小鼠无肿瘤发生,AOM模型组、5%MS干预组和10%MS干预组小鼠肿瘤发生率分别为86.7%、60.0%、41.7%,组间差异有统计学意义(P=0.048);5%MS干预组平均肿瘤数为1.07±1.10,10%MS干预组为0.67±0.89,均较AOM模型组的2.20±1.21少(P<0.05);10%MS干预组PI为32.0±3.9,均低于AOM模型组和5%MS干预组的59.9±4.4和41.7±4.9(P<0.05);10%MS干预组AI为15.0±2.4,均高于AOM模型组和5%MS干预组的6.9±1.4和9.3±1.5(P<0.05)。结论 MS对AOM诱导的小鼠大肠肿瘤具有化学预防作用,其机制为抑制肿瘤细胞增殖和诱导肿瘤细胞凋亡。

Objective To investigate the chemopreventive effects of mustard seed （MS） on azzoxymethane （AOM） induced colorectal tumor in mice and to explore its anticancer-related mechanisms. Methods A total of 60 mice of Kunming species were ran- domly divided into 4 groups of 15 each： AOM alone, AOM ＋5% MS, AOM ＋ 10% MS and the control group （ normal saline）. Colorec- tal tumorigenesis was induced by injecting AOM 10 mg/kg, subcutaneously, once a week for three weeks. Different doses of MS were given in diet during the study. Thirty-six weeks later, mice were sacrificed under cervical dislocation. The large intestine was isolated and flushed with ice-cold normal saline. The site, size and number of tumors were recorded. The incidence, the average number and the inhibitory rate of colorectal tumor in each group was determined. Tumor tissues were fixed, dehydrated and paraffin-embedded. The histological type was determined by HE staining. Expression of PCNA protein in tumor tissue was detected by immunohistochemical staining and tumor cell proliferation index （PI） was calculated. Apoptosis of tumor tissue was detected by TUNEL staining and tumor cell apoptosis index （AI） was calculated too. Results No tumor was found in control group. The colorectal tumor incidence, as com- pared to AOM model group （86. 7% ）, was reduced to 60. 0% by the 5% diet of mustard seeds and to 41.7% by the 10% diet of mustard seeds. The tumor incidence rates of the three groups were significantly different（P = 0. 048）, with the highest incidence rate in AOM model group, followed by 5% MS intervention group, 10% MS intervention group minimum. Tumor burden （tumors/mouse）was 2. 20 ± 1.21 in the AOM model group. Compared with model group, tumor burden was 1.07 ± 1.10 in 5% MS intervention group, and 0. 67 ± 0. 89 in 10% MS intervention group（P 〈 0.05）. PI in 10% MS intervention group was 32.0 ±3.9, which was lower than that in the AOM model group （59.9± 4.4） and 5 % MS intervention group （41.7 ± 4. 9）, with significant differences （ P 〈 0.05 ）. AI in 10% MS intervention group was 15.0 ± 2. 4,which was higher than that in the AOM model group （6. 9 ± 1.4） and 5 % MS intervention group （9. 3 ± 1.5）, with significant differences （P 〈 0. 05）. Conclusion The mustard seeds possess chemopreventive activity against colorectal cancer induced by AOM in mice, and can reduce the incidence of tumor and average number of tumor. The mustard seeds can reduce the expression of PCNA in colorectal tumor tissue, inhibit tumor cell proliferation and induce apoptosis of tumor cells.