gms | German Medical Science

Question: It has already been shown that cannabinoids have anti-tumorous effects against malignant gliomas. Cannabinoids activate the receptors TRPV1, TRPV2, CB1 and CB2 in the CNS, which are summarized as the receptors of the endogenous cannabinoid system. The endogenous transmitters are endocannabinoids which are modified fatty acids as anandamide and 2-arachidonoylglycerol. It has been proven that the stimulation of these receptors leads to apoptosis of glioma cells.In our research we want to characterize the expression of those receptors in gliomas. Furthermore we want to perform a functional characterization in order to find out under which condition a treatment with cannabinoids is most effective.

Methods: We performed mRNA expression analyses of the receptors in over 90 samples of gliomas and normal healthy brain tissues.We treated six glioblastoma cell lines with different concentrations of Arvanil which is a chemical analogon to anandamide. Using FACS we monitored intracellular calcium shifts after applying Arvanil. We further treated the cell lines with cannabidiol and cannabinol in order to show their dose-dependent cytotoxic effects. In a next step we added AM404 to the cannabis treatment. AM404 is an active metabolite of paracetamol. It inhibits the degradation of anandamide in the synaptic cleft thus elevating the concentration of endogenous cannabinoids and also acts as an agonist on the TRPV1 and CB1 receptor.

Results: The mRNA analyses showed a significantly different expression of TRPV1 and TRPV2 in gliomas compared to healthy brain. We saw significantly different expression levels of CB1 in gliomas compared to healthy brain which correlated inversely to the malignancy of the tumor.Arvanil has a dose-dependend cytotoxic effect on all tested cell lines. It caused an increase of intracelluluar calcium. In qPCR we saw an increase of spliced Xbp1 mRNA after the treatment with Arvanil which indicates that the tumor cells suffered from endoplasmatic reticulum stress.First results indicate that the cytotoxic effects of cannabis treatment are enhanced by the addition of AM404.

Conclusions: The combined treatment with a cannabinoid and AM404 has a more potent cytotoxic effect on glioma cells than the cannabinoid alone. Given that AM404 is fairly harmless in low doses, we can assume that the combination effect is created by the interaction of both substances. This might suggest that simple paracetamol can foster the efficiency of anti-cancer treatment in this setting.