- 學位論文
青蒿素及其衍生物之抗癌機制研究
Investigation into cellular mechanisms underlying the anti-cancer effects of artemisinin and its derivatives
摘要
從中國東晉時期開始黃花蒿(Artemisia annua L.) 被當作抗瘧疾之中草藥使用，到現代發現其主要活性化合物為青蒿素 (artemisinin)。最近有研究指出青蒿素及其衍生物具有抗癌的潛力，能夠抗癌細胞增生、促使癌細胞凋亡和抗爬行，但是其詳細機制仍然不清楚。本研究欲使用人類子宮頸癌細胞(HeLa)、人類大腸癌細胞(SW480及 HCT 116-原位癌和SW620-轉移癌)、人類正常角質細胞(HaCaT)和人類正常大腸細胞(HCoEpiC)，來研究青蒿素及其衍生物的抗癌活性及其機制。在細胞存活率實驗中可以得知，青蒿琥酯(artesunate)在癌細胞HeLa、HCT 116、SW480和SW620中有顯著的細胞毒殺性，但是在對正常細胞HaCaT和HCoEpiC則不具有顯著的細胞毒殺性。雙氫青蒿素(dihydroartemisinin)雖對正常細胞表現出顯著的細胞毒殺性，但所需要IC50高於癌細胞所需要的IC50。蒿甲醚(artemether)和蒿乙醚(arteether)在HeLa細胞中不具有細胞毒殺性，但對大腸癌細胞有選擇性的細胞毒殺性。在細胞爬行實驗中可以得知，在HeLa的細胞只有雙氫青蒿素具有抑制HeLa細胞的爬行能力，但青蒿琥酯和雙氫青蒿素皆具有顯著抑制SW480和HCT 116的細胞爬行能力，唯獨青蒿素在三株癌細胞都不具有抑制效果。另有文獻指出，細胞內鈣離子的調節與癌細胞爬行和腫瘤的生長有關，所以我們使用細胞內鈣離子測定染劑Fura-2 AM測定青蒿素及其衍生物是否會影響細胞內鈣離子濃度。在SW480細胞內鈣離子測定中，我們發現到青蒿素及其衍生物對內質網的鈣離子釋放不具有抑制作用，但是在對細胞外鈣離子的流入則有顯著的抑制效果。總結來說，青蒿素及其衍生物可能透過影響細胞內鈣離子濃度的調節而達到抑制大腸癌細胞的細胞增生和細胞爬行。
關鍵字
青蒿素並列摘要
Artemisia annua L. (Compositae) has been used as a Chinese herbal medicine with significant efficacy against malaria. Artemisinin (ART) is the major anti-malarial compound in this plant. Recent studies have suggested that ART and its derivatives have anti-cancer potentials, including anti-proliferation, pro-apoptotic and anti-migration activities. However, the underlying mechanisms are still unclear. In this study, human cervix cancer (HeLa), human colon cancer (SW480-primary, SW620-metastatic site: lymph node and HCT 116), human normal keratinocyte (HaCaT) cells and human colonic epithelial cells (HCoEpiC) were used to investigate cellular mechanisms underlying the anti-cancer effects of artemisinin and its derivatives. For cell viability, artesunate showed potent cytotoxic activities in HeLa, SW480, SW620 and HCT 116 cells, but not in HaCaT and HCoEpiC cells. dihydroartemisinin showed potent cytotoxic activities in HeLa, SW480, SW620, HCT 116, HaCaT and HCoEpiC cells, and its IC50 in HaCaT and HCoEpiC cells is higher than that of cancer cells. artemether and arteether had no cytotoxic effects in HeLa cells, but showed cytotoxic effects in colon cancer cells. For migration, artesunate and dihydroartemisinin, but not ART, significantly inhibited cellular migration of SW480 cells. Remodeling of Ca2+ homeostasis is involved in the regulation of cancer cell migration and tumor growth. Store-operated Ca2+ entry (SOCE) is a predominant pathway of Ca2+ entry in non-excitable cells, and is widely distributed in various cell types. We investigated whether artemisinin and its derivatives affect intracellular Ca2+. In the intracellular Ca2+ measurement assay of SW480 cells, we found that ART and its derivatives showed the little effect on ER Ca2+ release, but had significant inhibition on SOCE in a dose-dependent manner. Taken together, ART and its derivatives inhibit the proliferation and migration of colon cancer cells, possibly by affecting the SOCE.