姜黄素通过激活过氧化物酶体增殖物激活受体-γ预防大鼠大肠癌变的实验研究

Curcumin Inhibited Rat Colorectal Carcinogenesis by Activating PPARγ: an Experimental Study

目的探讨姜黄素对二甲基肼(DMH)诱导的大鼠大肠癌发生的防治作用及其机制。方法Wistar大鼠按随机数字表法分为模型组(20只)和姜黄素组(20只),同时设正常对照组(10只)。应用DMH 20mg/kg皮下注射诱导制备大鼠大肠癌模型。计算各组大鼠大肠肿瘤的诱癌率及抑制率;利用免疫组化和Western blot方法观察姜黄素对大鼠大肠黏膜组织过氧化物酶体增殖物激活受体-γ(peroxisome proliferatoractivated receptor gamma,PPARγ)表达的影响。培养人结肠癌HT 29细胞株,分为正常对照组、姜黄素加2-氯-5-硝基-N-苯基苯酰胺(GW9662)干预组和姜黄素组。采用MTT法检测不同浓度姜黄素对人结肠癌HT 29细胞株生长的抑制作用,Western blot方法检测姜黄素对人结肠癌HT 29细胞株PPARγ表达的影响。结果模型组大鼠诱癌率为80.00%(12/15),明显高于姜黄素组58.82%(10/17)(P<0.05),姜黄素对DMH诱导的大鼠大肠癌的抑制率达26.46%。与正常对照组比较,模型组和姜黄素组PPARγ表达均明显增强(P<0.01);与模型组同期比较,姜黄素组PPARγ表达亦明显增强(P<0.05)。MTT实验表明姜黄素可以抑制体外培养人结肠癌细胞株HT 29的增殖,且呈剂量和时间依赖性。与对照组比较,GW9662干预组及姜素组PPARγ表达均增强(P<0.01);与GW9662干预组比较,姜黄素组PPARγ表达亦增强(P<0.05)。结论姜黄素可抑制DMH诱导的大鼠大肠癌的形成,抑制体外培养的大肠癌细胞增殖,这种作用可能是通过激活PPARγ途径实现。

Objective To explore the chemopreventive effect of curcumin on DMH induced color- ectal carcinogenesis and the underlining mechanism. Methods Totally 40 Wistar rats were divided into the model group and the curcumin group by random digit table, 20 in each group. Meanwhile, a normal control group was set up （n =10）. A colorectal cancer model was induced by subcutaneously injecting 20 mg/kg DMH. The tumor incidence and the inhibition rate were calculated. The effect of curcumin on the ex- pression of peroxisome proliferator-activated receptor gamma （PPARγ） in rat colon mucosal tissues was observed using immunohistochemistry and Western blot. HT 29 cell line were cultured and divided into a control group, the curcumin ＋ GW9662 （2-chloro-5-nitro-N-4-phenylbenzamide） intervention group, and the curcumin group. The inhibition of different concentrations curcumin on HT 29 cell line was detected u- sing MTT. The expression of curcumin on PPARγ was also detected using Western blot. Results The tumor incidence was 80.00% （12/15 cases） in the model group, obviously higher than that of the curcu- min group （58.82%, 10/17 cases, P 〈0.05）. The inhibition rate of curcumin on DMH induced colorected carcinoma reached 26.46%. Compared with the normal control group, the expression of PPARγ protein was significantly increased in the curcumin group and the model group （P 〈0.01 ）. Compared with the model group at the same time point, the expression of PPARγ protein was significantly enhanced in thecurcumin group （P 〈0.05）. MTT analysis showed that curcumin could inhibit the proliferation of in vitro HT 29 cells in dose and time dependent manners. The expression of PPARγ protein was significantly in- creased in the GW9662 group and the curcumin group, showing statistical difference when compared with the normal control group （P 〈0.01 ）. Compared with the GW9662 group, the expression of PPARγ, protein was significantly increased in the curcumin group （P 〈0.01 ）. Conclusion Curcumin could inhibit DMH- induced rat colorectal carcinogenesis and the growth of in vitro cultured HT 29 cell line, which might be achieved by activating PPARγ signal transduction pathway.