| Abstract: | 惡性腫瘤中蟬聯十大癌症死亡原因第一位的就是肺癌，肺癌早期幾乎沒有什麼症狀，加上早期偵測相當困難，肺癌發現後的治療不易、容易轉移增加治療困難度，是肺癌與高死亡率劃上等號的主要原因。因此，研發有效的肺癌治療策略是一刻不容緩的課題。Withaferin A是從天然植物睡茄中萃取純化的類固醇內酯，近期研究顯示它具有誘導多種腫瘤細胞走向凋亡、降低炎症反應、抑制血管增生等功效。但是withaferin A在肺癌細胞是否也能呈現相同抗癌效果，還未被探討。本實驗即分析withaferin A對肺癌細胞的抗癌效果及作用機制。我們選用肺癌發生率高的「非小細胞」肺癌細胞株，進行實驗；且其中又以p53不同的三種表現型選出了三株細胞，分別進行withaferin A處理，觀察其對測試細胞造成的影響。實驗結果顯示，withaferin A對於不同p53表現型的肺癌細胞具有毒殺的效果，並測試caspase activity，發現caspase 3、8、9都有顯著表現，進一步利用JC-1分析，表示肺癌細胞凋亡與粒線體路徑相關，同時，withaferin A也會增加細胞內ROS的產生，且造成DNA的損傷。而在withaferin A低劑量處理時，可達到降低肺癌細胞轉移能力的效果，同時抑制癌細胞轉移的分子，E-cadherin會增加，而促進癌細胞轉移的分子vimentin的表現減少。此外，與癌症轉移能力相關的微小核醣核酸mir-10b，及與凋亡相關的mir-27a，也會受到withaferin A的抑制。本研究結果顯示，withaferin A可誘導肺癌細胞之凋亡，並可抑制肺癌細胞轉移，是一具有潛力開發為治療肺癌的天然化合物。
Lung cancer is the word-wide leading cause of tumor-associated deaths, in which the non-small cell lung cancer (NSCLC) accounts for 85% of all types of lung cancer. Most lung cancer patients are presented with advanced stages when diagnosed, which is a major reason of poor prognosis. Although the great development in clinical treatments of NSCLC, the overall five-year survival rate is still unsatisfied. Therefore, the development of more effective drugs for NSCLC is of great significance in clinic. Withaferin A (WA) is a steroidal lactone purified from the leaves of medicinal plant, Withania somnifera. Previous studies indicate that WA is one of the main biologically active withanolides, exerting a wide variety of pharmacological activities, including anti-inflammatory, cell death inducing, anti-tumor, radiosensitizing, as well as anti-angiogenic effects. However, the effects of WA in lung cancer remain unclear. In the current study, we examined the effects and underlying mechanisms of WA in lung cancer A549, H1299 and H1355 cell lines. Our results showed that treatment with WA induced cell death in both dose- and time-dependent manners. Interestingly, the cytotoxic effect of WA in lung cancer cells was independent of the status of p53, implying a broad therapeutic potential of WA for cancer patients treatment. Additionally, WA induced an apoptotic cell death in three tested lung cancer cells. This event was accompanied with the activation of caspase-3, caspase-9 and caspase-8. Data from JC-1 staining indicated that exposure to WA significantly disrupted the membrane potential of mitochondria, suggesting that WA might induce apoptosis via a mitochondrial pathway. Moreover, WA stimulated ROS generation and induced DNA damage in these tested cell lines. Besides, treatment with non-cytotoxic concentrations of WA impaired the migration of lung cancer A549 cells. Moreover, the expression of E-cadherin was up-regulated and vimentin was down-regulated upon WA exposure. Furthermore, two oncogenic microRNAs, mir-10b and mir-27a were significantly reduced when engaging with WA in lung cancer cells, these results are consistent with our observations that the increasing expressions of E-cadherin and Bax, which is a target protein of mir-10b and mir-27a, respectively. This study shows that WA induces the apoptosis or reduces the migration of human lung cancer cells, and has the potential to develop as a therapeutic agent for treatment of lung cancer patients. |
