Monoacylglycerol lipase promotes progression of hepatocellular carcinoma via NF-κB-mediated epithelial-mesenchymal transition

BACKGROUND: Monoacylglycerol lipase (MAGL), a critical lipolytic enzyme, has emerged as a key regulator of tumor progression, yet its biological function and clinical significance in hepatocellular carcinoma (HCC) is still unknown. METHODS: In this study, we used a tissue microarray containing samples from 170 HCC patients to evaluate the expression of MAGL and its correlation with other clinicopathologic characteristics. In addition, we investigated the regulating effects of MAGL on various HCC lines. Finally, we identified the NF-κB signaling pathway participated in MAGL-mediated epithelial-mesenchymal transition (EMT) using HCC cell lines with different metastatic potentials. RESULTS: The expression of MAGL was significantly higher in HCC tumors than in matched peritumor tissues. Specifically, high MAGL expression was found in tumors with larger tumor size, microvascular invasion, poor differentiation, or advanced TNM stage. In addition, the clinical prognosis for the MAGL(high) group was markedly poorer than that for the MAGL(low) group in the 1-, 3-, and 5-year overall survival times and recurrence rates of HCC patients. MAGL expression was an independent prognostic factor for both survival and recurrence after curative resection. Furthermore, the upregulation of MAGL in HCC cells promoted cell growth and invasiveness abilities, and accompanied by EMT. In contrast, downregulation of MAGL obviously inhibited these characteristics. Moreover, further investigations verified that MAGL facilitates HCC progression via NF-κB-mediated EMT process. CONCLUSIONS: Our findings demonstrate MAGL could promote HCC progression by the induction of EMT and suggest a potential therapeutic target, as well as a biomarker for prognosis, in patients with HCC. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13045-016-0361-3) contains supplementary material, which is available to authorized users.