urb-597 and Brain-Neoplasms

Inhibition of endocannabinoid degradation has been suggested as tool for activation of endogenous tumor defense. One of these strategies lies in blockade of fatty acid amide hydrolase (FAAH) which catalyzes the degradation of endocannabinoids (anandamide [AEA], 2-arachidonoylglycerol [2-AG]) and endocannabinoid-like substances (N-oleoylethanolamine [OEA], N-palmitoylethanolamine [PEA]). This study addressed the impact of two FAAH inhibitors (arachidonoyl serotonin [AA-5HT], URB597) on A549 lung cancer cell metastasis and invasion. LC-MS analyses revealed increased levels of FAAH substrates (AEA, 2-AG, OEA, PEA) in cells incubated with either FAAH inhibitor. In athymic nude mice FAAH inhibitors were shown to elicit a dose-dependent antimetastatic action yielding a 67% and 62% inhibition of metastatic lung nodules following repeated administration of 15 mg/kg AA-5HT and 5 mg/kg URB597, respectively. In vitro, a concentration-dependent anti-invasive action of either FAAH inhibitor was demonstrated, accompanied with upregulation of tissue inhibitor of matrix metalloproteinases-1 (TIMP-1). Using siRNA approaches, a causal link between the TIMP-1-upregulating and anti-invasive action of FAAH inhibitors was confirmed. Moreover, knockdown of FAAH by siRNA was shown to confer decreased cancer cell invasiveness and increased TIMP-1 expression. Inhibitor experiments point toward a role of CB2 and transient receptor potential vanilloid 1 in conferring anti-invasive effects of FAAH inhibitors and FAAH siRNA. Finally, antimetastatic and anti-invasive effects were confirmed for all FAAH substrates with AEA and OEA causing a TIMP-1-dependent anti-invasive action. Collectively, the present study provides first-time proof for an antimetastatic action of FAAH inhibitors. As mechanism of its anti-invasive properties an upregulation of TIMP-1 was identified.

Topics: Aged; Amidohydrolases; Animals; Apoptosis; Arachidonic Acids; Benzamides; Biomarkers, Tumor; Brain Neoplasms; Carbamates; Carcinoma, Non-Small-Cell Lung; Cell Movement; Cell Proliferation; Female; Gene Expression Regulation, Enzymologic; Humans; Lung Neoplasms; Male; Mice; Mice, Nude; Neoplasm Invasiveness; Receptor, Cannabinoid, CB2; Serotonin; Tissue Inhibitor of Metalloproteinase-1; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Opioids do not effectively manage pain in many patients with advanced cancer. Because anandamide (AEA) activation of cannabinoid type-1 receptors (CB1R) on nociceptors reduces nociception, manipulation of AEA metabolism in the periphery may be an effective alternative or adjuvant therapy in the management of cancer pain. AEA is hydrolyzed by the intracellular enzyme fatty acid amide hydrolase (FAAH), and this enzyme activity contributes to uptake of AEA into neurons and to reduction of AEA available to activate CB1R. We used an in vitro preparation of adult murine dorsal root ganglion (DRG) neurons co-cultured with fibrosarcoma cells to investigate how tumors alter the uptake of AEA into neurons. Evidence that the uptake of [(3)H]AEA into dissociated DRG cells in the co-culture model mimicked the increase in uptake that occurred in DRG cells from tumor-bearing mice supported the utility of the in vitro model to study AEA uptake. Results with the fluorescent AEA analog CAY10455 confirmed that an increase in uptake in the co-culture model occurred in neurons. One factor that contributed to the increase in [(3)H]AEA uptake was an increase in total cellular cholesterol in the cancer condition. Treatment with the FAAH inhibitor URB597 reduced CAY10455 uptake in the co-culture model to the level observed in DRG neurons maintained in the control condition (i.e., in the absence of fibrosarcoma cells), and this effect was paralleled by OMDM-1, an inhibitor of AEA uptake, at a concentration that had no effect on FAAH activity. Maximally effective concentrations of the two drugs together produced a greater reduction than was observed with each drug alone. Treatment with BMS309403, which competes for AEA binding to fatty acid binding protein-5, mimicked the effect of OMDM-1 in vitro. Local injection of OMDM-1 reduced hyperalgesia in vivo in mice with unilateral tumors in and around the calcaneous bone. Intraplantar injection of OMDM-1 (5μg) into the tumor-bearing paw reduced mechanical hyperalgesia through a CB1R-dependent mechanism and also reduced a spontaneous nocifensive behavior. The same dose reduced withdrawal responses evoked by suprathreshold mechanical stimuli in naive mice. These data support the conclusion that OMDM-1 inhibits AEA uptake by a mechanism that is independent of inhibition of FAAH and provide a rationale for the development of peripherally restricted drugs that decrease AEA uptake for the management of cancer pain.

Topics: Animals; Arachidonic Acids; Benzamides; Brain Neoplasms; Cannabinoid Receptor Antagonists; Carbamates; Cells, Cultured; Coculture Techniques; Disease Models, Animal; Endocannabinoids; Enzyme Inhibitors; Fibrosarcoma; Fluorescent Dyes; Ganglia, Spinal; Hyperalgesia; Indoles; Lactones; Male; Mice; Mice, Inbred C3H; Pain; Pain Threshold; Polyunsaturated Alkamides; Sensory Receptor Cells; Statistics, Nonparametric; Tritium

Inhibitors of the enzyme fatty acid amide hydrolase (FAAH), the principal enzyme involved in the metabolism of the endogenous cannabinoid anandamide, have potential utility in the treatment of disorders including inflammation and inflammatory pain. The carbamate compound URB597 (3'-carbamoyl-biphenyl-3-yl-cyclohexylcarbamate) potently and selectively inhibits FAAH by forming a covalent bond with a key serine residue of the enzyme. Little is known as to the pH dependency of this inhibition. Using a preincubation time of 10min, URB597 inhibited rat brain anandamide hydrolysis with pI(50) values of 7.19+/-0.02 and 7.75+/-0.06 at pH 6 and 8, respectively. The inhibition was time-dependent, and second order rate constants of approximately 0.15x10(6)M(-1)min(-1) (pH 6) and approximately 1.2x10(6)M(-1)min(-1) (pH 8) could be estimated. In intact C6 glioma cells and using a preincubation time of 10min, URB597 inhibited the hydrolysis of 250nM [(3)H]AEA hydrolysis with pI(50) values of 5.58+/-0.07 and 6.45+/-0.07 at extracellular pH values of 6 and 8, respectively. Since tissue pH is affected by inflammation, these data would suggest that the pH selectivity of the inhibition can contribute to the potency of the compound in vivo.

Topics: Amidohydrolases; Animals; Benzamides; Brain; Brain Neoplasms; Carbamates; Enzyme Inhibitors; Ethanolamine; Glioma; Hydrogen-Ion Concentration; Male; Rats; Rats, Sprague-Dawley; Rats, Wistar