Effect of thiabendazole on 17β-estradiol-induced mammary tumor in rats

Abstract

現代文明病倍增，癌症更是現代人最大隱憂，惡性腫瘤已躍居十大死因之首，乳癌為女性最主要癌症之一，發生率第一位，死亡率第四位，由於飲食西化及生活型態改變影響下，乳癌發生率年年增高，因此預防與治療乳癌乃新藥重要挑戰。本實驗室先前研究顯示，染劑Rhodamine B口服投予懷孕大鼠第0-20天時誘發胚胎早死亡現象，而該染劑具促進環化酶（Aromatase ）作用，因此增加睪固酮（testosterone）轉化為雌二醇濃度，因此本實驗室接著再設計共同以Rhodamine B與咪唑類藥物Thiabendazole（TBZ）口服處理懷孕大鼠第0-20天，目的在以具環化酶拮抗作用之TBZ緩解Rhodamine B對大鼠胚胎早死亡之影響。結果顯示，TBZ可緩解胚胎死亡影響。 基於此一原則，本研究目的在探討TBZ是否可以拮抗以雌二醇誘發大鼠乳腺腫瘤。實驗設計為以雌二醇5、10及15 mg/pellet/rat個別混合處理TBZ 50、100及200 mg/pellet/rat。處理動物為10週齡Wistar品系雌大鼠。處理方法為埋植錠劑於大鼠背頸部皮下，觀察期間10個月。結果顯示，大部分大鼠體重隨處理埋植時間增加而增加，肉眼與病理組織判斷腫瘤發生率，雌二醇處理組隨劑量增加而增加，但最高劑量與中劑量相同。TBZ則未誘發乳腺腫瘤，混合處理雌二醇5 mg/pellet/rat與TBZ 50、100及200 mg/pellet/rat未緩解乳腺腫瘤，但混合處理雌二醇10或15 mg/pellet/rat個別與TBZ 50、100及200 mg/pellet/rat，儘管統計上不顯著但有減少乳腺腫瘤現象。免疫染色結果顯示，乳腺腫瘤與動情素受體（ERα、ERβ） 及環化酶表現，雌二醇處理組顯著誘發ERα表現但ERβ與環化酶則否；TBZ處理對ERα、ERβ與環化酶表現不明顯；雌二醇單一劑與TBZ不同劑量混合處理則具劑量反應關係減少ERα表現。 本研究利用TBZ拮抗環化酶作用對雌二醇誘發乳癌緩解作用似乎具快達統計上顯著水準程度，但因乳癌形成機制仍不明朗，環化酶作用機制在乳癌形成究竟扮演何種程度有待進一步探討。The diseases are increasing with industrialization especially in cancer, which is one of top ten. Breast cancer is one of the most serious diseases with number one in incidence and number four in death rate. Due to the westernized food and change of live style the incidence of breast cancer is increasing with year. It is quite important for us to develop new drugs for breast cancer. Our previous study showed that pregnant rat was orally administered in utero exposure with stain Rhodamine B resulted in severe embryo lethality. Previous report showed that Rhodamine B increased the aromatase activity, which transfer testosterone into estradiol. Based on the aromatase antagonistic activity by thiabendazole our laboratory conduct a study to investigate the effect of co-treatment with thiabendazole and Rhodamine B on embryo lethality in rats. Results showed that thiabendazole completely relieved the embryo lethality in rats. Based on the hypothesis this study aim to investigate if the thiabendazole antagonize the estradiol-induced mammary tumors in rats. Wistar rats were implanted with 5, 10 and 15 mg 17β-estradiol/pellet/rat, 50, 100 and 200 mg/pellet/rat thiabendazole, 5, 10 and 15 mg 17β-estradiol/pellet/rat each and 50, 100 and 200 mg/pellet/rat thiabendazole. Wistar rats, 10 week old, were implanted for 10 months. Results showed that body weight were increased with treatment period. The incidence of breast tumor with gross and pathology were as follows. Positive control 17β-estradiol induced breast tumor with dose response while thiabendazole did not. Though the result is not statistically significant, co-treatment with 10 and 15 mg 17β-estradiol/pellet/rat and 50, 100 and 200 mg/pellet/rat thiabendazole decreased the incidence of breast cancer when compared with 17β-estradiol alone. Immunohistochemistry data showed that 17β-estradiol induced ERα activity but not in ERβ and aromatase. Co-treatment with 17β-estradiol each and various thiabendazole significantly decreased the ERα activity with dose response. We concluded that the thiabendazole antagonistic effect on the 17β-estradiol induced breast cancer and the result is near the significant level statistically. Owing to the unclear underlying mechanism of breast cancer and the role of aromatase in caner induction it is need to be done for the prevention.摘要(中文).............................................i 摘要(英文)............................................iii 目次...................................................V 圖目次................................................vii 第一章、前言...........................................1 第二章、文獻探討.......................................2 第一節、乳癌流行病學...............................2 第二節、乳癌的形成因素.............................2 　　第三節、乳癌的治療.................................4 　　第四節、雌激素與乳癌...............................5 　　第五節、雌激素受體.................................7 　　第六節、乳腺腫瘤動物模式...........................8 　　第七節、腦下垂體...................................9 　　第八節、Thiabendazole..............................10 第三章、材料與方法.....................................12 　　第一節、動物處理...................................12 　　第二節、H&E染色....................................12 　　第三節、免疫組織化學染色法.........................13 　　第四節、西方墨點法.................................14 　　第五節、統計方法...................................17 第四章、結果...........................................18 　　第一節、動物臨床症狀觀察...........................18 　　第二節、乳腺腫瘤發生率.............................19 第三節、H&E染色....................................19 　　第四節、免疫組織化學染色法.........................20 　　第五節、西方墨點法.................................21 第五章、討論...........................................23 第六章、結論...........................................26 參考書目...............................................5