植化素紫檀芪合併抗癌用藥誘發膀胱癌細胞產生細胞自噬

Abstract

Pterostilbene是Resveratrol的結構類似物，已有研究證實具抗氧化、抗發炎和抗癌的藥理功效。膀胱癌為泌尿道系統常見的惡性腫瘤，臨床用藥Gemcitabine搭配Cisplatin或Carboplatin是目前治療膀胱癌的一線化療藥物。為確保癌症病患的治療權益和安全性，以傳統的化療藥物為基準再結合具抗癌功效的化合物來治療患者比單一採用抗癌功效的化合物來得安全且接收度較高。本研究使用植化素Pterostilbene合併臨床用藥進行實驗。Pterostilbene與Resveratrol相比，在T24細胞中Pterostilbene有較佳的細胞抑制效果，且誘發較高細胞自噬比例。Pterostilbene合併臨床用藥後，顯著增加臨床用藥的生長抑制率且合併藥物指數在T24細胞中皆為協同效用，但在E7細胞中大多為結抗作用。Pterostilbene合併臨床用藥處理T24細胞後並沒有增加Sub-G1(細胞凋亡)比例，但顯著增加細胞自噬的比例，且誘發細胞自噬之相關機制為抑制class I PI3K/mTOR/p70S6K途徑和活化MEK/ERK1/2及class III PI3K途徑。此外，T24細胞經由同樣加藥處理後增加細胞衰老-galactosidase的活性，是藉由Ras-p-Rb pathway，但處理E7細胞後卻沒有發現細胞衰老現象。使用細胞自噬抑制劑3-methyladenine與U0126處理T24細胞來觀察細胞凋亡、細胞自噬和衰老的關聯性，發現細胞自噬與細胞凋亡呈現正相關，且生長抑制率涉及到細胞自噬，但細胞自噬抑制劑對細胞衰老卻無顯著影響。期望Pterostilbene能在臨床上輔助化療藥物治療，減低患者的臨床用藥，減少化療時的副作用，改善並提升醫療品質。Pterostilbene and its structural analog Resveratrol, produced naturally by plants when under attack by pathogens, have been reported to display anticarcinogenic effects. Bladder cancer is the ninth most common deadly cancer worldwide and the fourteenth cause of cancer death in Taiwan. Gemcitabine plus Cisplatin or Carboplatin has been used as the first-line treatment for patients with locally advanced and metastatic bladder cancer. To determine if addition of phytochemical Pterostilbene enhances cytotoxicity of the clinical drugs, grade III human bladder cancer T24 cells and immortalized human uroepithelial E7 cells was used. Pterostilbene elevated the percentages of cells with AVOs to a greater extent than Resveratrol using flow cytometry. Pterostilbene enhanced the cytotoxicity of the clinical drugs, producing a synergistic effect on T24 cells but an antagonism effect on E7 cells using MTT analysis. Pterostilbene induced senescence on T24 cells but not E7 cells examined by senescence-associated expression of -galactosidase activity using microscopy. The induced senescence in T24 cells may be mediated by the Ras-p-Rb pathway. Western blot analysis further indicated that Pterostilbene-induced autophagy may be mediated by inhibition of the class I PI3K/mTOR/p70S6K pathway as well as activation of the ERK1/2 pathway and the class III PI3K pathway in T24 cells. The use of autophagy inhibitor 3-methyladenine and U0126 separately demoted the anti-cancer drugs-induced cytotoxicity, percentages of cells at the Sub-G1 phase, but not the β-galactosidase activity. Taken together, our data suggested that addition of Pterostilbene exhibited better cytotoxicity on cancer T24 cells than immortalized E7 cells and the enhanced cytotoxicity on T24 cells was associated with induction of cytotoxic form of autophagy but not the senescence.