穿心蓮(Andrographis paniculata)為爵床科植物，以往被用為抗菌、消炎解熱及免疫促進之傳統治療藥物。其中被認為最主要的活性成分為雙萜類的穿心蓮內酯。近年來陸續有研究發現穿心蓮內酯亦表現出抑癌效果。因此，我們欲進一步證實並探討其抗癌活性。首先，利用多種人類及小鼠癌細胞株進行毒殺試驗、DAPI細胞核染色法及DNA片段分析，發現穿心蓮內酯的確對於癌細胞具有抑制增生並導致細胞凋亡的作用。接下來以流式細胞儀(FACS)分析細胞週期的變化，可觀察到癌細胞在處理藥物後，其細胞週期停滯在G0/G1期。為釐清其中所牽涉的細胞週期調控蛋白，我們藉由西方墨點法(Western blotting)觀察到穿心蓮內酯可提升癌細胞中細胞週期抑制因子(cyclin dependent kinase inhibitor, CDKI)，p21的表現量並降低細胞週期素依賴性激酶(cyclin dependent kinase, CDK)，CDK4的含量。此外，於小鼠原位癌模式中發現穿心蓮內酯在活體內亦有抑制腫瘤細胞生長的能力；另外發現在給予藥物後，腫瘤中血管新生情形相對於控制組有減少的現象。於是進一步利用大鼠主動脈環實驗觀察到穿心蓮內酯具有抑制主動脈微脈管形成的作用。而後，由酶譜(gelatin zymography) 以及細胞移行分析(cell migration assay)亦發現穿心蓮內酯可降低癌細胞移行能力並抑制與腫瘤轉移極具相關性的物質，基質金屬蛋白酶(Matrix Metalloproteinase, MMP)-2及-9，的分泌。最後，藉由小鼠黑色素瘤肺轉移模式證實穿心蓮內酯在動物體內具有抑制癌症轉移的效果。以上結果顯示穿心蓮內酯在活體內及活體外皆具有抗癌活性。然而，在抗癌治療策略走向多元化的現今，穿心蓮內酯在詳細抗癌機制以及在臨床所發揮的抗癌功效上，還有很大的空間值得去深究探討。

Andrographolide (AG) is a bicyclic diterpenoid lactone isolated from the leaves of Andrographis paniculata, an herbal medicine used traditionally as an anti-inflammatory drug for the treatments of laryngitis, diarrhea and rheumatoid arthritis. The present investigation aims at making a systemic study, both in vitro and in vivo, of the anti-cancer cell proliferation, cell cycle arrest, anti-angiogenesis, anti-metastasis and anti-tumor activities of AG. In vitro, AG shows anti-proliferative activity toward a variety of human cancer cell lines. FACS and Western blot analyses indicate that AG induces cells to undergo cell cycle arrest at the G0/G1 phase by inducing the expression of p21, a cyclin dependent kinase inhibitor (CDKI), and a concomitant decrease of cyclin dependent kinase 4 (CDK4). AG also exhibits anti-angiogenesis activity in both the immunostaining of CD31 and rat aortic ring assay. In a gelatin zymography assay for matrix metalloproteinase (MMP), AG inhibits the secretion of MMP-2 and -9 from A549 cells, suggesting AG is involved in suppressing metastasis. The notion is strengthened by the finding that AG inhibits the migrations of A549 and B16-F10 cells by either the Boyden chamber assay or the wound healing assay. The anti-metastasis of AG is finally supported in vivo by the reduction of number of metastasized lung nodules after a tail vein injection of B16-F10 melanoma cells into C57BL/6J mice. AG also significantly suppresses the primary implanted Lewis lung carcinoma tumor in the same mouse strain. Our data suggest that AG is an interesting pharmacophore with anti-cancer activities in vitro and in vivo. Its molecular mechanism of action deserves further elucidation in the future studies.

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