羅布麻萃取物在人類前列腺癌細胞株的抗癌作用

前列腺癌不管在西方或東方的癌症死亡率都有逐年增高的趨勢;根據 2013 年台灣衛生福利部國民健康署統計,前列腺癌佔國人主要癌症死亡排名第七名;American Cancer Society 則指出前列腺癌佔美國男性死亡排名第二名。因此如何有效防治前列腺癌是目前醫學研究人員極欲深入了解的議題。相關文獻及資料持續提到中草藥對於抗癌的成效,過去的研究也證實中草藥中萃取出的多酚與黃酮類物質具有抗癌的效果。本研究以一系列羅布麻萃取物為主,探討其抑制惡性前列腺癌細胞株 PC3 生長及增生的潛力。細胞毒殺試驗(MTT assay)測試結果發現,編號 8 萃取物有最好的抑制癌細胞生長的效果(IC50:172 μg/mL,24h)。以流式細胞儀(flow cytometry)分析之結果發現羅布麻 8 號的萃取物會造成細胞週期 G2/M 停滯(G2/M arrest)及細胞凋亡(apoptosis)的現象,且此現象呈現劑量依賴性(dose-dependent)。化學分析實驗發現羅布麻萃取物內含有大量酚類(phenol)、黃酮類 (flavonoid),同時發現其有很強的抗氧化。經過核磁共振光譜儀及質譜儀進行結構鑑定和分析,可以得知有效抑制癌細胞生長/增生的羅布麻萃取物中的有效主成分是羽扇豆醇(Lupeol)。因此,我們利用市售羽扇豆醇標準品再次進行上述細胞試驗。結果發現其抑制癌細胞生長/增生的效果及特性與編號 8 羅布麻萃取物相似(IC50:23 μg/mL,24h);相同的,流式細胞儀分析和 DAPI 染色法也觀察到癌細胞 G2/M 停滯的現象。總結研究成果,本論文發現,編號 8 羅布麻萃取物對於開發成前列腺癌治療的藥物或保健食品具有相當的潛力。

關鍵字

羅布麻；前列腺癌；抗癌

並列摘要

Malignancy is most aware as a description of cancer, which is difficult to cure. Surgery is referred to as the oldest procedure in treating cancer, about 60 -70% of cancer patients will undergo surgery, either by itself or in combination with other therapies, such as chemotherapy. Prostate cancer is an age-related cancer, ranking as the seventh leading cause of cancer death among men in Taiwan, and the second in the United States. Several traditional herbal medicines have been found to have antitumor effects, previous studies indicated that numerous Chinese herbal medicines not only demonstrated anti-inflammatory, anti-oxidative and anti-tumor effect, but also exerted low toxic side effects. In this study, the possible cytotoxic or growth-inhibitory effect of the Apocynum venetum (Luobuma) extracts was investigated. MTT assays were performed and found out the #8 fraction of the Apocynum venetum extracts possessed the greatest ability in halting the growth/proliferation of the prostate cancer (PC3). Further, flow cytometric analysis were conduct to confirm the effects of Apocynum venetum extracts in inducing apoptosis in PC3, and it was found that Apocynum venetum extract #8 was able to increase the G2/M phase ratio during cell cycle progression. Moreover nuclear condensation was also confirmed by DAPI staining in PC3 cells. Further the total phenolic and total flavonoids contents were measured. The anti-oxidant ability of the Apocynum venetum extracts #8 was also determined by ABTS+, DPPH and FRASC assay, respectively. NMR and Mass spectrometric analyses confirmed the most abundant compound presented in Apocynum venetum extract fraction#8 is lupeol.Commercial lupeol standard was purchased to test its anti-proliferation effect on PC-3 cancer cells, similar results was observed. Based on the collective observations, it was thus concluded that Apocynum venetum extract containing lupeol plays an important role in activating/mediating apoptosis, and G2/M phase arrest in PC3 prostate cancer cells. Apocynum venetum may hold the great promise as one effective compound for treating prostate cancer or becoming a functional food ingredient to reduce risk of prostate cancer.