Cannabidiol, a non-psychoactive cannabinoid compound, affects metalloproteinases and pro-survival intracellular pathways in u87-mg human glioma cell line

Malignant gliomas are the most common primary brain tumors characterized by a high ability to invade the surrounding brain parenchyma as leading cause of tumor recurrence and treatment failure. Recently, we have shown that the non-psychoactive cannabinoid compound cannabidiol (CBD) induced apoptosis of human glioma cells in vitro and tumor regression in vivo (1, 2). It has been reported that glioma cell migration and invasiveness are hallmarks of gliomas that account in large part for their poor prognosis. To this aim, the first goal of the present study was to investigate the anti-migratory action of CBD by assessing the ability to inhibit U87-MG human glioblastoma cell migration. We found that U87-MG cells exposed to CBD for 16 and 24 h, induced a significant inhibition in the rate of cell motility in scratch wound healing assay. Since among the various factors involved in motility and invasion, matrix metalloproteinases (MMPs) play a pivotal role in promoting tissue breakdown through degradation of extracellular matrix components, we decided to investigate the capability of CBD to interfere with MMPs function. We found that U87-MG cells exposed for 24 h to different concentrations of CBD showed a significant inhibition of MMP-2 release in the supernatants of cell cultures, as evaluated by ELISA assay. CBD also decreased the MMP-2 gelatinolytic activity, as detected by gelatine zymography analysis. Besides, CDB inhibited the expression profile of a set of proteins specifically involved in tumor invasion such as MMP-9, TIMP-1, TIMP-2, TIMP-4, uPa and SerpinE-1. The exposure of U87-MG cells to CBD significantly down-regulated signalling pathways critical for cell survival and proliferation as Akt and Erk. Finally, we tested the effect of CBD on hypoxia-inducible factor HIF-1, one of the most important transcriptional factors involved in tumor invasion and angiogenesis, under experimental conditions mimicking hypoxic state (i.e. exposure to 50 M CoCl2 or 1% pO2 for 24 h). We found that CBD induced a significant decrease of HIF-1 levels under both simulated and actual hypoxic conditions. In conclusion, the present investigation adds further insights into the antitumoral action of the non-psychoactive CBD, showing multiple mechanisms through which the cannabinoid inhibits glioma cell growth and motility. As CBD is a natural compound without psychotropic and side effects, these data lead us to consider CBD as a new potential anticancer drug useful in the management of gliomas.