Abstract 4236: Moscatilin inhibits invasion by suppressing urokinase plasminogen activator expression through Akt inactivation in human hepatocellular carcinoma cells

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Purpose: Hepatocellular carcinoma (HCC) frequently shows early invasion into blood vessels as well as intrahepatic metastasis. The innovations of novel small-molecule agents to block HCC invasion and subsequent metastasis are urgently needed. Moscatilin is a bibenzyl derivative extracted from the stems of a traditional Chinese medicine, Orchid Dendrobrium loddigesii. Previous studies demonstrated that moscatilin exerted potent cytotoxic effects against numerous lines of cancer cells. Recently, moscatilin has been reported to suppress tumor angiogenesis. However, the anti-metastatic property of moscatilin has not been elucidated. Methods: Multiple molecular and pharmacological approaches such as invasion assay, MTT assay, ELISA assay, zymography, real-time PCR, Western blot, luciferase reporter gene assay, and chorioallantoic membrane (CAM) intravasation assay were used to determine the anti-metastatic effects of moscatilin in SK-Hep-1 cells, a highly metastatic human HCC cell line. Results: We found moscatilin inhibited cell invasion in a concentration-dependent manner in SK-Hep-1 cells in the absence of cytotoxicity. Moscatilin did not affect proteolytic activities of matrix metalloproteinase (MMP) -2 and MMP-9, but profoundly suppressed urokinase plasminogen activator (uPA) activity. We next found that moscatilin substantially inhibited protein expression of uPA but did not obviously impair uPAR and PAI-1 expression. To examine the upstream signaling of uPA suppression, the ERK1/2, Akt, mTOR, and NF-κB signaling pathways were evaluated in moscatilin-treated cells. We demonstrated that moscatilin dramatically inhibited Akt phosphorylation, but not ERK1/2 phosphorylation. Moscatilin did not reduce the phosphorylation of mTOR as well as of components of the translational machinery including p70S6K, 4E-BP1 and eIF4E. Additionally, IKKα/β phosphorylation, IκBα phosphorylation, p65 phosphorylation at Ser536, and κB-luciferase activity were not inhibited by moscatilin. However, Moscatilin repressed the expression of uPA mRNA, suggesting that moscatilin regulated the uPA production in transcriptional level. Transfection of constitutively active Akt (Myr-Akt) partly restored the moscatilin induced Akt inactivation. The inhibition of cell invasion, uPA activity and gene expression in response to moscatilin were also attenuated. Moreover, we found that moscatilin significantly inhibited cell metastasis using CAM intravasation assay, a well established in vivo model for metastasis. Conclusions: This study provides evidence that moscatilin induces Akt inactivation and uPA suppression, which leads to inhibition of invasion and metastasis in human HCC cells. Our results suggest that moscatilin is a novel anti-metastatic agent, which has great potential for further development for treating cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4236. doi:10.1158/1538-7445.AM2011-4236