Increasing Antiproliferative Properties of Endocannabinoids in N1E-115 Neuroblastoma Cells through Inhibition of Their Metabolism

Abstract

The antitumoral properties of endocannabinoids received a particular attention these last few years. Indeed, these endogenous molecules have been reported to exert cytostatic, apoptotic and antiangiogenic effects in different tumor cell lines and tumor xenografts. Therefore, we investigated the cytotoxicity of three N-acylethanolamines – N-arachidonoylethanolamine (anandamide, AEA), N-palmitoylethanolamine (PEA) and N-oleoylethanolamine (OEA) - which were all able to time- and dose-dependently reduce the viability of murine N1E-115 neuroblastoma cells. Moreover, several inhibitors of FAAH and NAAA, whose presence was confirmed by RT-PCR in the cell line, induced cell cytotoxicity and favored the decrease in cell viability caused by N-acylethanolamines. The most cytotoxic treatment was achieved by the co-incubation of AEA with the selective FAAH inhibitor URB597, which drastically reduced cell viability partly by inhibiting AEA hydrolysis and consequently increasing AEA levels. This combination of molecules synergistically decreased cell proliferation without inducing cell apoptosis or necrosis. We found that these effects are independent of cannabinoid, TRPV1, PPARα, PPARγ or GPR55 receptors activation but seem to occur through a lipid raft-dependent mechanism. These findings further highlight the interest of targeting the endocannabinoid system to treat cancer. More particularly, this emphasizes the great potential benefit of designing novel anti-cancerous therapies based on the association of endocannabinoids and inhibitors of their hydrolysis.

Evidence for Bidirectional Endocannabinoid Transport across Cell Membranes

“…Therefore, when [ethanolamine-1-3 H]AEA is used in the presence of either FAAH or EMT inhibitors, the intracellular radioactivity from the lipophilic phase should be differentially affected. FAAH inhibition leads to higher intracellular levels of AEA compared with vehicletreated cells, as reported for URB597 (56,74,75), whereas blocking the cell membrane transport leads to a reduced cellular penetration of AEA, as reported for several inhibitors (19 -21). FAAH inhibitors can lead to different readouts, depending on many factors, such as AEA concentration, distinct incorporation of ethanolamine in different cell types, and method of detection (radioactivity versus absolute quantification).…”

“…FAAH inhibitors can lead to different readouts, depending on many factors, such as AEA concentration, distinct incorporation of ethanolamine in different cell types, and method of detection (radioactivity versus absolute quantification). This could be a major explanation for the different readouts reported for FAAH inhibitors on AEA cellular uptake (25,56,74,76). If FAAH is blocked, AEA is still transported inside the cell, where it segregates into cytoplasmic reservoirs, such as the recently described carrier proteins or adiposomes (9 -11, 73), whereas in FAAH-active cells, AEA is rapidly hydrolyzed.…”

Antitumor effect of pyrrolo-1,5-benzoxazepine-15 and its synergistic effect with Oxaliplatin and 5-FU in colorectal cancer cells

“…13 Moreover the FAAH inhibitor URB597 increased the antiproliferative effects of endocannabinoids in neuroblastoma, melanoma and non-small cell lung cancer cells. [25][26][27] Therefore, the identification of a novel compound that binds and inhibits FAAH raises the obvious question of whether this molecule may interfere with proliferation of target cells.…”

Palmitoylethanolamide: From endogenous cannabimimetic substance to innovative medicine for the treatment of cannabis dependence

“…Like THC, PEA could produce a direct or indirect activation of CB1 and CB2 receptors [56]. Furthermore, it acts as an agonist at PPARa, PPARc, GPR55 and TRPV1 receptors [57].…”