吲哚-3-甲醇对DMBA诱导大鼠乳腺肿瘤的预防效果

Prevention effect of indole-3-carbinol on DMBA-induced mammary tumors in rats

背景与目的:近年来,乳腺癌化学预防成为热门研究方向,目前临床常用的化学预防药物,如他莫昔芬(三苯氧胺)在发挥防癌作用的同时,也出现了很多副作用。这样就促使人们从多方面寻找高效无毒的化学预防药物。通过流行病学的研究发现天然食物中有效成分与降低癌症的发病率存在着一定关系,如β-胡萝卜素、维甲酸、绿茶素等,从日常食物中提取防癌剂便为化学预防药物的发展指明了新的方向。本研究探讨了十字花科植物(花椰菜,结球甘蓝等)中的有效成分吲哚-3-甲醇(I3C)对大鼠乳腺癌的预防作用以及对大鼠乳腺肿瘤中ER受体表达抑制作用。方法:①将40只43d龄SD大鼠40只按体重分层后随机分为不预防给药组(DMBA灌胃)、高剂量给药组(I3C,100mg/d)、低剂量给药组(I3C,50mg/d)、溶剂对照组,每组各10只。高剂量给药组与低剂给药量组预防性给予吲哚-3-甲醇1周,1周后不预防给药组、高剂量给药组与低剂量给药组分别30mg/mlDMBA致癌剂一次性灌胃造模(1ml/只),之后高剂量给药组与低剂量给药组分别给于吲哚-3-甲醇100mg/d,与50mg/d至实验结束(共100d),观察各组乳腺肿瘤发生时间,记录数目并计算肿瘤体积,光镜下对乳腺肿瘤进行病理分类。②对各组大鼠乳腺肿瘤用免疫组化S-P方法测定ERα及ERβ的表达情况。结果:①各组大鼠乳腺肿瘤数目及体积均值(x±s):高剂量给药组荷瘤大鼠3只,低剂量给药组荷瘤大鼠3只,与不预防给药组荷瘤大鼠9只比较,差异有显著性(P<0.05);高剂量给药组荷瘤7个,平均肿瘤体积(8±5)×102mm3,低剂量给药组荷瘤总数13个,平均肿瘤体积(23±4)×102mm3,与不预防给药组荷瘤总数21个,平均肿瘤体积(31±5)×102mm3,差异有显著性(P<0.05);而高剂量给药组与低剂量给药组之间进行比较P>0.05,差异无显著性。②光镜下组织学观察,高剂量给药组与低剂量给药组的乳腺肿瘤浸润性导管癌发生,分化程度高,侵袭性均明显低于不预防给药组。③ER受体在各组乳腺肿瘤中的表达:吲哚-3-甲醇高剂量给药组和低剂量给药组(高剂量给药组+低剂量给药组)ER受体阳性表达率为50%(10/20),不预防给药组ER受体阳性表达率85.7%(18/21);而高剂量给药组和低剂量给药组ER受体阴性表达率50%(10/20),不预防给药组的14.2%(3/21),它们之间比较均有显著差异(χ2=6.0341,P<0.05)。其中ERα与ERβ在高剂量给药组和低剂量给药组中的阳性表达亦明显低于不预防给药组(P<0.05),有显著差异。结论:吲哚-3-甲醇在抑制乳腺肿瘤发生中有明显效果,但高剂量与低剂量之间并没有显著差异;并且能够有效阻断肿瘤中ER受体的表达,使其表达下调。

Background and purpose： In recent years, chemo-prevention of breast cancer has been heavily investigated, the current clinical chemical prevention drug, such as tamoxifen, plays a role in the prevention of cancer, but it also has many side effects. This prompts many people to seek effectively non-toxic chemical prevention drugs. Epidemiological studies found that there was a certain relationship between active ingredients in natural food and the prevention of the breast cancer, such as 13 - carotene, retinoic acid, and green tea etc. It points to a new direction of development of chemical prevention drugs that are extracted from anti-cancer agents in the human daily food. This experiment studies indole-3-carbinol, which is the active ingredient from cruciferous plants （ broccoli, cabbage, etc. ）, on the prevention of the cancer in experimental animal models （ mammary tumor model in rats）, and the inhibition of ER receptor expression in mammary tumors. Methods： ①40 Wistar rats 43 days old were randomly divided into the model groups （ only DMBA lavage）, high-dose group （ I3C, 100 mg/d）, low-dose group （ I3C, 50 mg/d）, and the control group. Each group contained 10 animals. High-dose group and low-dose group were given indole-3-carbinol for a week, the model group, the high-dose group and low-dose group were intragastrically administrated DMBA 30 mg/ml at 1 ml per rats, then the high-dose group and low-dose group were given indole-3-carbinol 100 mg/d and 50 mg/d to the last date of the experiment （ approximately 100 days）, respectively. The incidence of mammary tumors was observed, the number of tumors was recorded and the volumes were measured. The histological structures were observed under the light microscopy and the tumors were classified by pathological standard. ②ER alpha and ER beta expression was observed in all mammary tumors of each group by S-P immunohisto- chemical method. Results： ①The number of rat mammary tumor and the average size of tumor volumes （ x ± s） ： the number of rats beating the tumor was 3 in high-dose group and 3 in low-dose, there were statistically significant differences from the number in the control group （ 9 tumors, P 〈 0.05） ; the number of tumors was 7 in high-dose group, 13 in low-dose group, and 21 in the control group, respectively, and the average tumor size was （ 8 ± 5） × 10^2 mm^3 in high-dose group , （23 ±4） × 10^2 mm^3 in low-dose group compared to （31 ± 5） × 10^2 mm^3 in model group, there was also significant difference （ P 〈 0.05） ; but the volumes of tumors in the high-dose group and low-dose group were not statistically different （ P 〉 0.05）. Conclusions： Indole-3-carbinol has significant effects on the prevention of breast cancer, but it is not dose dependent; and it can effectively block ER receptor expression of tumors.