研究中草藥S10對多形性神經膠質母細胞瘤及其類癌幹細胞之存活抑制作用

Abstract

Glioblastoma (GBM) 是腦癌中常見的一種惡性腫瘤，現有的治療方式多以手術切除搭配化療進行，但現有的治療方式成效不彰，且由於GBM具有高度侵入性，因此預後大多不佳，現有藥物對其療效也有限。中草藥應用在中國傳統醫學治療長達數千年之久，但比起西方藥物，其研究相對較少，近年來也開始有研究指出中草藥對某些癌症細胞具有毒殺效果，因此我們也期望能從中發展出治療GBM的有效藥物。本篇研究中，我們使用 Human GBM cell line U251-MG 和 U373-MG，利用順天堂藥廠股份有限公司提供之水萃中草藥，篩選出具有抑癌成效的中草藥，另外也使用U251-MG衍生之類癌幹細胞以及利用CD133標記分離出之CD133+ 癌幹細胞，進一步的確認中草藥抑制癌幹細胞的效果。在我們的研究中發現，中草藥水萃物S10不僅對GBM癌細胞及類癌幹細胞的生長有抑制效果，同樣也能有效抑制CD133+ 的GBM癌幹細胞生長，而且S10並不會對正常小鼠星狀膠細胞的生長造成影響。另外，在分子機制上，我們用西方墨點法證明了S10會降低Akt及ERK的活化，並有效降低幹細胞相關蛋白質CD133及Sox2的表現。此外，為了研究S10在活體模式的效果，我們使用NOD.CB17-PrKdC-SCID/Jnarl 免疫缺陷小鼠異種移植U373-CD133+ 衍生之類癌幹細胞並發現 S10可以抑制腫瘤之形成與生長。而將長出的腫瘤取出體外，進行初級細胞培養後，也能看到給予藥物的組別，其形成群落的能力比控制組來的差。我們更進一步探討S10中的有效成分，其中S10-I2與S10相同皆可有效抑制GBM癌細胞及其類癌幹細胞的存活，並減少GBM的癌幹細胞特性，降低Akt與ERK的活化。S10-I2對初級培養的正常小鼠星狀膠細胞亦無毒性，後續若能釐清S10-I2之詳細作用機轉，以及在活體內的效果，將提升S10-I2在臨床應用上的可能。

Glioblastoma (GBM) is the most common brain tumor in adults. The current therapy is surgical removal combined with chemical therapy. However, its effect is limited, because of the highly invasiveness and drug resistance of GBM. The studies of Chinese Herbal Medicine (CHM) are scarce compared with those of Western medicines, but CHM has been used in Chinese society for thousands of years. Recently, more studies showed that CHM can effectively inhibit the growth of specific cancer cells. Therefore, we prospect to develop the potential herbs as new treatments for GBM. We used human GBM cell lines, U251-MG and U373-MG, as the drug screening platform to screen herb extracts from Sun Ten Pharmaceutical Company, and identified the herbs which effectively inhibit the growth of GBM cancer cells. The effects of herb extracts on GBM stemloids were further confirmed in U251-derived-tumorspheres and U251-CD133+-tumorspheres. We found that S10 herb extracts effectively inhibits the growth of GBM cancer cell lines, tumorspheres, and CD133+-cancer stem cells. We also showed that S10 does not affect the growth of primary-cultured normal mouse astrocytes. Moreover, we demonstrated that S10 reduces Akt and ERK activation and inhibits the expression of stem cell associated protein, CD133 and Sox2. To confirm the effects of S10 in vivo, we used NOD.CB17-PrKdC-SCID/Jnarl mice injected with CD133+-tumorspheres as xenotransplantation model. S10 extracts inhibits the growth of GBM tumors in mouse. The primary-cultured tumor cells from S10-treated mice showed reduced colony formation ability. Furthermore, we identified one active principle of S10, S10-I2, which also effectively inhibits the growth of GBM cancer cells and GBM stemloids without affect the growth of primary-cultured normal mouse astrocytes. S10-I2 also reduces Akt and ERK activation and inhibits the expression of stem cell associated protein, CD133 and Sox2. In conclusion, S10 and S10-I2 both have significant inhibitory effects on GBM. Moreover, S10-I2 is a potential compound which may be developed as the new treatment for GBM.