共價鍵結基因毒性藥物與葡萄糖轉運蛋白抑制劑作為治療結直腸癌藥物的研究

Abstract

鈉依賴型葡萄糖轉運蛋白第一型(SGLT 1)和葡萄糖轉運蛋白第一型(GLUT1)在癌細胞中不正常地大量表現，以及癌細胞藉由大量攝取葡萄糖而對基因毒殺藥物產生抗藥性，顯見藉由葡萄糖轉運蛋白為標的的抗癌藥物設計為一個可行的方向。本論文根據以上因素，合成了以5-FU和irinotecan透過酸敏感與高還原力的生物可分解的linker設計，鍵結到SGLT1的抑制劑phlorizin和GLUT的抑制劑phloretin的複合分子，並進一步探討這兩種複合分子的活性。 在本論文中我們設計了兩種linker，單一釋放機轉是選擇利用酯鍵將抗癌藥物(5-FU和irinotecan)與標靶基團(phlorizin和phloretin)結合得到化合物30-33。另外，雙重釋放機轉乃是使用同時具有酯鍵和thiol-maleimide的linker，它將抗癌藥物(5-FU和irinotecan)與標靶基團(phlorizin和phloretin)結合得到化合物34-37，利用酸性或高還原條件下不穩定的特性，作為雙重釋放機轉 5-FU衍生物的化合物30在pH 6、7和8會進行水解，三天後水解程度分別為4.1%、47.7%和88.9% ，中性偏鹼性下水解程度會提升。在人類血漿中24小時釋放約為52%。 化合物31在高還原力的10 mM GSH下三天後仍無與GSH進行交換而釋放活性藥物。 5-FU衍生物30、31、34、35在HCT-116和HT29癌細胞中進行活性測試。發現IC50略低於5-FU。5-FU在HCT-116和HT29癌細胞中的IC50分別為9.6 μM和8.3 μM，化合物30、31、34、35在HCT-116和HT29癌細胞中的IC50分別落在6.0-7.5 μM和4.4-6.8 μM。 本論文針對葡萄糖轉運蛋白為標的的研究雖未能有效抑制癌細胞株生長，但以此方向為藥物設劑的方式可提供抗癌藥物設計的新方向。

Sodium-dependent glucose cotransporter1 (SGLT1) and glucose transporter (GLUT) are abnormally expressed in cancer cells. Increase of glucose uptake in cancer cells causes the resistance of genotoxic agents. Combining above observations, glucose transporter as a target for designing anticancer agents is feasible. Based on this point, 5-FU and irinotecan, which were conjugated to SGLT1 inhibitor (phlorizin) or GLUT inhibitor (phloretin) by tailor-made biodegradable linker, were designed as novel anticancer agents and their cytotoxicities were performed. In this thesis, two kind of linkers were designed. Anticancer agents (5-FU or irinotecan) and targering groups (phlorizin and phloretin) were conjugated with a acid-labile ester bond to give compounds 30-33 which was considered as the single release mechanism, and conjugated not only through a acid-labile ester bond but also through a bio-reductive thio-maleimide bond to give compounds 34-37 which were considered as the double release mechanism. 5-FU derivatives 30 would undergo hydrolysis under pH 6, 7 and 8 buffer and the percentage of release after 3 days incubation was 4.1%, 47.7%, 88.9%, respectively. Thy level of hydrolysis would increase as the pH increase. In rat plasma, the conjugate 30 was completely realeased within 5 min and in human plasma, the percentage of release was 52% within 24h. It showed more stable in human plasma than in rat plasma. Compound 31 was not exchanged with high concentration of GSH to release 5-FU even after 3 days incubation. The cytotoxicities of 5-FU derivatives 30, 31, 34, 35 in HCT-116 and HT29 cancer cell were found slightly increase compared to 5-FU. IC50 of 5-FU in HCT-116 and HT29 cancer cells was 9.6 μM and 8.3 μM, respectively. IC50 of 30, 31, 34, 35 were ranged form 6.0-7.5 μM and 4.4-6.8 μM for HCT-116 and HT29, respectively. Although using glucose transporter as a target for designing new anticancer agents did not prove to be efficient in current study, for the study focus on this topic might lead to open a new avenue for anticancer drug development.