骨肉瘤是最常見的惡性骨腫瘤。手術徹底切除是最典型的治療方法。然而高轉移能力及轉移後五年存活率大約僅60%。全新、有效、低毒性及符合成本效益的天然或人工化合物有可能成為抗癌輔助的療法選擇。甘草查爾酮A (Licochalcone A)是由甘草根萃取出的類黃酮且有廣泛的藥理活性。在本次研究中將利用細胞及動物實驗，探討甘草查爾酮A對於人類骨肉瘤細胞的抗癌能力及可能的作用機轉。結果發現甘草查爾酮A能降低人類骨肉瘤細胞存活及誘導凋亡。甘草查爾酮A能誘導凋亡蛋白?-3及凋亡蛋白?-9活化及聚ADP-核糖聚合?裂解。甘草查爾酮A誘導的細胞凋亡同時伴隨促凋亡調節因子及抗凋亡調控因子不平衡所引起的粒線體膜電位功能喪失進而活化凋亡蛋白?-9。甘草查爾酮A誘導的細胞凋亡能被凋亡蛋白?抑制劑及粒線體膜電位抑制劑所緩轉。磷酸化p38有絲分裂原活化蛋白激?在甘草查爾酮A誘導的細胞凋亡中有明顯增加。使用p38有絲分裂原活化蛋白激?抑制劑BIRB796及p38有絲分裂原活化蛋白激?小分子干擾核糖核酸皆可使細胞免於被甘草查爾酮A誘導凋亡。最後的動物實驗證明甘草查爾酮A能抑制異體移植的143B骨肉瘤細胞成長。我們的結論發現，經細胞及動物實驗結果顯示甘草查爾酮A對於人類骨肉瘤細胞的抗癌能力是藉由p38有絲分裂原活化蛋白激?調節粒線體內生性凋亡路徑而產生。
Osteosarcoma is the most common malignant bone tumor. Complete radical en bloc resection is generally the typical treatment. However, the high metastatic ability of osteosarcoma and the five-year survival rate for patients with metastasis is only approximately 60%. New, effective, less-toxic, cost-effective natural compounds could be useful as novel anti-cancer therapeutics. Licochalcone A (LicA) has wide spectrum of pharmacological activities and is a flavonoid isolated from the root of Glycyrrhiza glabra. In the present study, we investigated the anti-cancer effects and potential mechanisms of LicA in human osteosarcoma cell lines in vitro and in vivo. LicA decreased cell viability and induced apoptosis in human osteosarcoma cells. In addition, LicA induced caspase-3 and caspase-9 activation and poly-ADP-ribose polymerase (PARP) cleavage, which displayed features of apoptotic signals. LicA-induced apoptosis accompanies loss of mitochondrial membrane potentials (MMPs) by inducing the imbalance of Bax/Bcl-2 leading to the activated process of caspase-9. LicA-induced apoptosis was blocked by Z-VAD (caspase inhibitor) or tauroursodeoxycholic acid (MMPs inhibitor). Phosphorylated p38 MAPK was speci?cally activated in LicA-induced apoptotic pathway. BIRB796 (p38 MAPK inhibitor) and p38 MAPK siRNA can prevent cells from LicA-induced apoptosis. Finally, an in vivo study revealed that LicA significantly inhibited 143B xenograft tumor growth. In conclusion, these findings demonstrate that LicA has antitumor activities against human osteosarcoma cells through p38 MAPK regulation of mitochondria-mediated intrinsic apoptotic pathways in vitro and in vivo.
