Withaferin A與TRAIL引起人類口腔癌細胞株細胞 凋亡協力作用之研究

Abstract

Withaferin A是純化自一種印度傳統草藥 withania somnifera 的withanolide類化合物。它具有增強免疫、抗菌、抗發炎、抗血管新生的效果。 在台灣，口腔癌占男性癌症死亡的第四名，雖然化療和放療的技術被廣泛使用在治療口腔癌，但病患的五年存活率沒有明顯的改善。 Withaferin A 被發現能誘導許多癌細胞株細胞凋亡，如:乳癌、腎癌、肺癌、子宮頸癌等，因此有成為抗癌藥的潛力。 我們的研究發現，Withaferin A 可明顯抑制口腔癌細胞株 SAS和Ca9-22生長，且濃度愈高或作用時間愈長，抑制效應就愈明顯 (SAS與Ca9-22 之24 小時 IC50 分別為1.1μM及1.2μM)。 藉由流式細胞儀分析細胞之細胞週期結果顯示，以 1.1μM與1.2μM的 Withaferin A 處理 SAS 及 Ca9-22 細胞株 分別在12及24小時後，會明顯增加sub-G1 期細胞的百分比，可見得 Withaferin A 也可引起人類口腔癌細胞的細胞凋亡。西方墨點法和caspase抑制劑的實驗結果指出Withaferin A誘導Fas、DR4和DR5的表現，造成caspase 8(膜受體路徑)和caspase 9(粒線體路徑)活化，最後導致細胞凋亡。次毒性濃度(0.6μM)的 Withaferin A與TRAIL(5ng/ml)對口腔癌細胞株細胞凋亡有協力的效果。對於Withaferin A是否可當作口腔癌抗癌藥物則需要再以更精確的動物實驗及臨床試驗作更深入的評估其抗癌的功效。

Withanolide-like compound, Withaferin A, is purified from an Indian traditional herb, withania somnifera. Withanolide is one of steroidal lactones, it is antioxidant and has clinical medical activities, such as immunity increasing, anti-bacteria, anti-inflammatory, anti-angiogenesis, and antitumor. The last is the most striking activity. In Taiwan, oral cancer is the fourth cancer causing dead, although the technologies in radiotherapy and chemotherapy have been promoted, the five-years-survival rate of patients was no significant improvement. Withaferin A has been found to induce apoptosis in many kinds of cancer cell lines and regarded as a potential anti-cancer drug, ex: breast cancer’ kidney cancer’ lung cancer’ cervical cancer. In this study, we showed the Withaferin A inhibited strongly the growths of oral cancer cell lines, SAS and Ca9-22 with dose-dependent and time-dependent manners(IC50 value 1.1μM and 1.2μM respectively). Withaferin A increased the percentage of sub-G0/G1 dramatically (1.1μM and 1.2μM respectively). With the results of Western blot and trial of caspase inhibitor treatments, the results showed Withaferin A induced Fas’ DR4 and DR5 expressions, then activated caspase 8 (death receptor pathway) and also caspase 9 (mitochondrial pathway) , and final induce cell death. Withaferin A in sub-toxic concentration (0.6μM) could facilitate the sensitivity of oral cancer cell line to TRAIL (5ng/ml) and let to apoptosis. In conclusion, Withaferin A can be used as oral cancer drugs but needs to further research to confirm it efficacy.