Inhibition of fatty acid amide hydrolase activates Nrf2 signalling and induces heme oxygenase 1 transcription in breast cancer cells

Abstract

BACKGROUND AND PURPOSE Endocannabinoids such as anandamide (AEA) are important lipid ligands regulating cell proliferation, differentiation and apoptosis. Their levels are regulated by hydrolase enzymes, the fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MGL). Here, we investigated whether FAAH or AEA are involved in NF (erythroid-derived 2)-like 2 (Nrf2)/antioxidant responsive element (ARE) pathway. EXPERIMENTAL APPROACH The aim of this study was to analyse the effects of AEA or FAAH inhibition by the URB597 inhibitor or FAAH/siRNA on the activation of Nrf2-ARE signalling pathway and heme oxygenase-1 (HO-1) induction and transcription. KEY RESULTS Endogenous AEA was detected in the immortalized human mammary epithelial MCF-10A cells (0.034 ng per 10 6 cells) but not in MCF-7 or MDA-MB-231 breast cancer cells. Because breast tumour cells express FAAH abundantly, we examined the effects of FAAH on Nrf2/antioxidant pathway. We found that inhibition of FAAH by the URB597 inhibitor induced antioxidant HO-1 in breast cancer cells and MCF-10A cells. RNAi-mediated knockdown of FAAH or treatment with AEA-activated ARE-containing reporter induced HO-1 mRNA and protein expression, independent of the cannabinoid receptors, CB1, CB2 or TRPV1. Furthermore, URB597, AEA and siRNA-FAAH treatments induced the nuclear translocation of Nrf2, while siRNA-Nrf2 treatment and Keap1 expression blocked AEA, URB597 and si-FAAH from activation of ARE reporter and HO-1 induction. siRNA-HO-1 treatment decreased the viability of breast cancer cells and MCF-10A cells. CONCLUSIONS AND IMPLICATIONS These data uncovered a novel mechanism by which inhibition of FAAH or exposure to AEA induced HO-1 transcripts and implicating AEA and FAAH as direct modifiers in signalling mediated activation of Nrf2-HO-1 pathway, independent of cannabinoid receptors.

N-palmitoyl serotonin alleviates scopolamine-induced memory impairment via regulation of cholinergic and antioxidant systems, and expression of BDNF and p-CREB in mice

“…Consistent with this, this study demonstrated that scopolamine significantly increased lipid peroxidation in the brain, while significantly restored by Pal-5HT (1 mg/kg). Probably in support of this, previous report [22] indicated that antioxidant enzymes such as HO-1, GCLC and NQO-1 were remarkably induced by Pal-5HT through Nrf2 activation via PI3K/Akt or p-38 MAPK signaling pathways, irrespective of cannabinoids receptor activation in HT-22 cells challenged with glutamate. From these, it is suggested that the Pal-5HT-mediated restoration of cognitive function may be related primarily to its antioxidant action, as well evidenced from the suppression of scopolamine-induced oxidative damage in brain tissue.…”

“…Meanwhile, cannabinoids, lipid mediators in nervous systems [20], have been observed to show anti-inflammatory or anti-allergy activities [21,22]. Recently, phenolic cannabinoids such as N-acyl dopamines or N-arachidonoyl 5-hydroxytryptamine (5HT), present in the M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 4 brain as well as other tissues, were reported to show anti-inflammatory and immunosuppressive action [23].…”

“…Recently, phenolic cannabinoids such as N-acyl dopamines or N-arachidonoyl 5-hydroxytryptamine (5HT), present in the M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 4 brain as well as other tissues, were reported to show anti-inflammatory and immunosuppressive action [23]. Furthermore, a recent publication [22] suggested that some endogenous cannabinoids could exert anti-inflammatory action via the activation of Nrf2 signaling pathway, independent of cannabinoid receptors (CBs).…”

N-Stearoyltyrosine Protects Against Glutamate-Induced Oxidative Toxicity by an Apoptosis-Inducing Factor (AIF)-Mediated Caspase-Independent Cell Death Pathway

“…Agents with the potential to intervene in multiple injuries would offer a novel therapeutic strategy for stroke/cerebral ischemia (4,5). Endocannabinoid AEA can protect neurons from damages through intervening in multiple injuries, such as inhibiting glutamate release (19 -21), scavengering free radicals (6,22,23), reduc ing Ca 2+ influx (24,25), and decreasing inflammatory response (8). However, it is difficult to use AEA in clinical practice because it is rapidly degraded (26).…”

Anti-Inflammatory and Antioxidant Actions of <b><i>N</i></b>-Arachidonoyl Serotonin in RAW264.7 Cells

“…Recently, N -acyl 5HTs were reported to show anti-allergic and anti-inflammatory actions in mast cells or nerve cells [13,14] . Besides, some endocannabinoids were known to induce antioxidant enzymes via the activation of nuclear factor-E2-related factor-2 (Nrf2) pathway [15] . Our recent study showed that N -palmitoyl 5HT remarkably augmented the level of antioxidant enzymes such as heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic subunit (GCLC) or NAD(P)H quinine oxidoreductase-1 (NQO-1) via the activation of Nrf2 pathway in HT-22 cells [14] .…”