The CB1/VR1 agonist arvanil induces apoptosis through an FADD/caspase-8-dependent pathway

Functional Selectivity of Cannabinoid Type 1 G Protein-Coupled Receptor Agonists in Transactivating Glycosylated Receptors on Cancer Cells to Induce Epithelial-Mesenchymal Transition Metastatic Phenotype

Understanding the role of biased G protein-coupled receptor (GPCR) agonism in receptor signaling may provide novel insights into the opposing effects mediated by cannabinoids, particularly in cancer and cancer metastasis. GPCRs can have more than one active state, a phenomenon called either 'biased agonism', 'functional selectivity', or 'ligand-directed signaling'. However, there are increasing arrays of cannabinoid allosteric ligands with different degrees of modulation, called 'biased modulation', that can vary dramatically in a probe- and pathway-specific manner, not from simple differences in orthosteric ligand efficacy or stimulus-response coupling. Here, emerging evidence proposes the involvement of CB1 GPCRs in a novel biased GPCR signaling paradigm involving the crosstalk between neuraminidase-1 (Neu-1) and matrix metalloproteinase-9 (MMP-9) in the activation of glycosylated receptors through the modification of the receptor glycosylation state. The study findings highlighted the role of CB1 agonists AM-404, Aravnil, and Olvanil in significantly inducing Neu-1 sialidase activity in a dose-dependent fashion in RAW-Blue, PANC-1, and SW-620 cells. This approach was further substantiated by findings that the neuromedin B receptor inhibitor, BIM-23127, MMP-9 inhibitor, MMP9i, and Neu-1 inhibitor, oseltamivir phosphate, could specifically block CB1 agonist-induced Neu-1 sialidase activity. Additionally, we found that CB1 receptors exist in a multimeric receptor complex with Neu-1 in naïve, unstimulated RAW-Blue, PANC-1, and SW-620 cells. This complex implies a molecular link that regulates the interaction and signaling mechanism among these molecules present on the cell surface. Moreover, the study results demonstrate that CB1 agonists induce NFκB-dependent secretory alkaline phosphatase (SEAP) activity in influencing the expression of epithelial-mesenchymal markers, E-cadherin, and vimentin in SW-620 cells, albeit the impact on E-cadherin expression is less pronounced compared to vimentin. In essence, this innovative research begins to elucidate an entirely new molecular mechanism involving a GPCR signaling paradigm in which cannabinoids, as epigenetic stimuli, may traverse to influence gene expression and contribute to cancer and cancer metastasis.

Cannabidiol regulates apoptosis and autophagy in inflammation and cancer: A review

Cannabidiol (CBD) is a terpenoid naturally found in plants. The purified compound is used in the treatment of mental disorders because of its antidepressive, anxiolytic, and antiepileptic effects. CBD can affect the regulation of several pathophysiologic processes, including autophagy, cytokine secretion, apoptosis, and innate and adaptive immune responses. However, several authors have reported contradictory findings concerning the magnitude and direction of CBD-mediated effects. For example, CBD treatment can increase, decrease, or have no significant effect on autophagy and apoptosis. These variable results can be attributed to the differences in the biological models, cell types, and CBD concentration used in these studies. This review focuses on the mechanism of regulation of autophagy and apoptosis in inflammatory response and cancer by CBD. Further, we broadly elaborated on the prospects of using CBD as an anti-inflammatory agent and in cancer therapy in the future.

Comparison of the Anticancer Effects of Arvanil and Olvanil When Combined with Cisplatin and Mitoxantrone in Various Melanoma Cell Lines-An Isobolographic Analysis

Due to the unique structures of arvanil and olvanil, the drugs combine certain properties of both cannabinoids and vanilloids, which makes them able to stimulate both TPRV1 and CB1 receptors and causes them to be interesting agents in the setting of carcinoma treatment. The aim of this study was to investigate the cytotoxic and anti-proliferative effects of arvanil and olvanil when administered alone and in combination with cisplatin (CDDP) and mitoxantrone (MTX), using various primary (A375, FM55P) and metastatic (SK-MEL 28, FM55M2) human malignant melanoma cell lines. The results indicate that both arvanil and olvanil inhibited (dose-dependently) the viability and proliferation of various malignant melanoma cells, as demonstrated by MTT and BrdU assays. The safety profile of both arvanil and olvanil tested in human keratinocytes (HaCaT) and normal human melanocytes (HEMa-LP) revealed that neither arvanil nor olvanil caused significant cytotoxicity in HaCaT and HEMa-LP cell lines in LDH and MTT assays. Isobolographically, it was found that both arvanil and olvanil exerted additive interactions with MTX and antagonistic interactions with CDDP in the studied malignant melanoma cell lines. In conclusion, the combinations of arvanil or olvanil with MTX may be considered as a part of melanoma multi-drug therapy; however, the combination of these compounds with CDDP should be carefully considered due to the antagonistic interactions observed in the studied malignant melanoma cell lines.

Nonpungent N-AVAM Capsaicin Analogues and Cancer Therapy

Capsaicin displays robust growth-inhibitory activity in multiple human cancers. However, the feasibility of capsaicin as a clinically relevant anticancer drug is hampered by its adverse side effects. This concern has led to extensive research focused on the isolation and synthesis of second-generation nonpungent capsaicin analogues with potent antineoplastic activity. A major class of nonpungent capsaicin-like compounds belongs to the N-acyl-vanillylamide (N-AVAM) derivatives of capsaicin (hereafter referred as N-AVAM capsaicin analogues). This perspective discusses the isolation of N-AVAM capsaicin analogues from natural sources as well as their synthesis by chemical and enzymatic methods. The perspective describes the pharmacokinetic properties and anticancer activity of N-AVAM capsaicin analogues. The signaling pathways underlying the growth-inhibitory effects of N-AVAM capsaicin analogues have also been highlighted. It is hoped that the insights obtained in this perspective will facilitate the synthesis of a second generation of N-AVAM capsaicin analogues with improved stability and growth-suppressive activity in human cancer.

Anticancer Activity of Natural and Synthetic Capsaicin Analogs

The nutritional compound capsaicin is the major spicy ingredient of chili peppers. Although traditionally associated with analgesic activity, recent studies have shown that capsaicin has profound antineoplastic effects in several types of human cancers. However, the applications of capsaicin as a clinically viable drug are limited by its unpleasant side effects, such as gastric irritation, stomach cramps, and burning sensation. This has led to extensive research focused on the identification and rational design of second-generation capsaicin analogs, which possess greater bioactivity than capsaicin. A majority of these natural capsaicinoids and synthetic capsaicin analogs have been studied for their pain-relieving activity. Only a few of these capsaicin analogs have been investigated for their anticancer activity in cell culture and animal models. The present review summarizes the current knowledge of the growth-inhibitory activity of natural capsaicinoids and synthetic capsaicin analogs. Future studies that examine the anticancer activity of a greater number of capsaicin analogs represent novel strategies in the treatment of human cancers.

Involvement of TRPM2 and TRPV1 channels on hyperalgesia, apoptosis and oxidative stress in rat fibromyalgia model: Protective role of selenium

Fibromyalgia (FM) results in pain characterized by low selenium (Se) levels, excessive Ca2+ influx, reactive oxygen species (ROS) production, and acidic pH. TRPM2 and TRPV1 are activated by ROS and acid; nevertheless, their roles have not been elucidated in FM. Therefore, we investigated the contribution of TRPM2 and TRPV1 to pain, oxidative stress, and apoptosis in a rat model of FM and the therapeutic potential of Se. Thirty-six rats were divided into four groups: control, Se, FM, and FM + Se. The Se treatment reduced the FM-induced increase in TRPM2 and TRPV1 currents, pain intensity, intracellular free Ca2+, ROS, and mitochondrial membrane depolarization in the sciatic (SciN) and dorsal root ganglion (DRGN) neurons. Furthermore, Se treatment attenuated the FM-induced decrease in cell viability in the DRGN and SciN, glutathione peroxidase, and reduced glutathione and α-tocopherol values in the DRGN, SciN, brain, muscle, and plasma; however, lipid peroxidation levels were decreased. Se also attenuated PARP1, caspase 3, and 9 expressions in the SciN, DRGN, and muscle. In conclusion, Se treatment decreased the FM-induced increase in hyperalgesia, ROS, apoptosis, and Ca2+ entry through TRPM2 and TRPV1 in the SciN and DRGN. Our findings may be relevant to the elucidation and treatment of FM.

Synergistic interaction of the cannabinoid and death receptor systems - a potential target for future cancer therapies?

Cannabinoid receptors have been shown to interact with other receptors, including tumor necrosis factor receptor superfamily (TNFRS) members, to induce cancer cell death. When cannabinoids and death-inducing ligands (including TNF-related apoptosis-inducing ligand) are administered together, they have been shown to synergize and demonstrate enhanced antitumor activity in vitro. Certain cannabinoid ligands have been shown to sensitize cancer cells and synergistically interact with members of the TNFRS, thus suggesting that the combination of cannabinoids with death receptor (DR) ligands induces additive or synergistic tumor cell death. This review summarizes recent findings on the interaction of the cannabinoid and DR systems and suggests possible clinical co-application of cannabinoids and DR ligands in the treatment of various malignancies.

Cannabidiol Reduces Leukemic Cell Size - But Is It Important?

The anti-cancer effect of the plant-derived cannabinoid, cannabidiol, has been widely demonstrated both in vivo and in vitro. However, this body of preclinical work has not been translated into clinical use. Key issues around this failure can be related to narrow dose effects, the cell model used and incomplete efficacy. A model of acute lymphoblastic disease, the Jurkat T cell line, has been used extensively to study the cannabinoid system in the immune system and cannabinoid-induced apoptosis. Using these cells, this study sought to investigate the outcome of those remaining viable cells post-treatment with cannabidiol, both in terms of cell size and tracking any subsequent recovery. The phosphorylation status of the mammalian Target of Rapamycin (mTOR) signaling pathway and the downstream target ribosomal protein S6, were measured. The ability of cannabidiol to exert its effect on cell viability was also evaluated in physiological oxygen conditions. Cannabidiol reduced cell viability incompletely, and slowed the cell cycle with fewer cells in the G2/M phase of the cell cycle. Cannabidiol reduced phosphorylation of mTOR, PKB and S6 pathways related to survival and cell size. The remaining population of viable cells that were cultured in nutrient rich conditions post-treatment were able to proliferate, but did not recover to control cell numbers. However, the proportion of viable cells that were gated as small, increased in response to cannabidiol and normally sized cells decreased. This proportion of small cells persisted in the recovery period and did not return to basal levels. Finally, cells grown in 12% oxygen (physiological normoxia) were more resistant to cannabidiol. In conclusion, these results indicate that cannabidiol causes a reduction in cell size, which persists post-treatment. However, resistance to cannabidiol under physiological normoxia for these cells would imply that cannabidiol may not be useful in the clinic as an anti-leukemic agent.

Non-pungent long chain capsaicin-analogs arvanil and olvanil display better anti-invasive activity than capsaicin in human small cell lung cancers

The nutritional compound capsaicin inhibits the invasion of many types of human cancers. The clinical development of capsaicin as an anti-cancer drug is limited due to its unfavorable side effects like burning sensation, stomach cramps, gut pain and nausea. This study compared the anti-invasive activity of capsaicin to non-pungent long chain capsaicin analogs, namely arvanil and olvanil, in human small cell lung cancer cells. Boyden chamber invasion assays revealed that arvanil and olvanil displayed improved anti-invasive activity relative to capsaicin in human SCLC cells. The results of the Boyden chamber assay were confirmed by the spherical invasion assay, and similar results were obtained. The anti-invasive activity of arvanil, olvanil and capsaicin were independent of TRPV and CB1 receptors. Furthermore, the anti-invasive activity of arvanil, olvanil and capsaicin was mediated by the AMPK pathway. Depletion of AMPK levels by siRNA methodology abrogated the anti-invasive activity of arvanil, olvanil and capsaicin. The non-pungent capsaicin analogs arvanil and olvanil display improved anti-invasive activity relative to capsaicin in human SCLC cells. These agents may represent the second generation of capsaicin-like compounds which are more potent than the parent molecule and have a better side effect profile.

Dronabinol has preferential antileukemic activity in acute lymphoblastic and myeloid leukemia with lymphoid differentiation patterns

Background

It has been previously demonstrated in several cancer models, that Dronabinol (THC) may have anti-tumor activity – however, controversial data exists for acute leukemia. We have anecdotal evidence that THC may have contributed to disease control in a patient with acute undifferentiated leukemia.

Methods

To test this hypothesis, we evaluated the antileukemic efficacy of THC in several leukemia cell lines and native leukemia blasts cultured ex vivo. Expression analysis for the CB1/2 receptors was performed by Western immunoblotting and flow cytometry. CB-receptor antagonists as well as a CRISPR double nickase knockdown approach were used to evaluate for receptor specificity of the observed proapoptotic effects.

Results

Meaningful antiproliferative as well as proapoptotic effects were demonstrated in a subset of cases – with a preference of leukemia cells from the lymphatic lineage or acute myeloid leukemia cells expressing lymphatic markers. Induction of apoptosis was mediated via CB1 as well as CB2, and expression of CB receptors was a prerequisite for therapy response in our models. Importantly, we demonstrate that antileukemic concentrations are achievable in vivo.

Conclusion

Our study provides rigorous data to support clinical evaluation of THC as a low-toxic therapy option in a well defined subset of acute leukemia patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-2029-8) contains supplementary material, which is available to authorized users.

Synthetic and Biological Studies of Sesquiterpene Polygodial: Activity of 9-Epipolygodial against Drug-Resistant Cancer Cells

Polygodial, a terpenoid dialdehyde isolated from Polygonum hydropiper L., is a known agonist of the transient receptor potential vanilloid 1 (TRPV1). In this investigation a series of polygodial analogues were prepared and investigated for TRPV1-agonist and anticancer activities. These experiments led to the identification of 9-epipolygodial, which has antiproliferative potency significantly exceeding that of polygodial. 9-Epipolygodial was found to maintain potency against apoptosis-resistant cancer cells as well as those displaying the multidrug-resistant (MDR) phenotype. In addition, the chemical feasibility for the previously proposed mechanism of action of polygodial, involving the formation of a Paal-Knorr pyrrole with a lysine residue on the target protein, was demonstrated by the synthesis of a stable polygodial pyrrole derivative. These studies reveal rich chemical and biological properties associated with polygodial and its direct derivatives. These compounds should inspire further work in this area aimed at the development of new pharmacological agents, or the exploration of novel mechanisms of covalent modification of biological molecules with natural products.

Submembraneous microtubule cytoskeleton: biochemical and functional interplay of TRP channels with the cytoskeleton

Much work has focused on the electrophysiological properties of transient receptor potential channels. Recently, a novel aspect of importance emerged: the interplay of transient receptor potential channels with the cytoskeleton. Recent data suggest a direct interaction and functional repercussion for both binding partners. The bi-directionality of physical and functional interaction renders therefore, the cytoskeleton a potent integration point of complex biological signalling events, from both the cytoplasm and the extracellular space. In this minireview, we focus mostly on the interaction of the cytoskeleton with transient receptor potential vanilloid channels. Thereby, we point out the functional importance of cytoskeleton components both as modulator and as modulated downstream effector. The resulting implications for patho-biological situations are discussed.

Effect of anandamide on erythrocyte survival

The endocannabinoid anandamide (Arachidonylethanolamide, AEA) is known to induce apoptosis in a wide variety of nucleated cells. The present study explored whether anandamide induces suicidal death of erythrocytes or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine exposure at the erythrocyte surface. Eryptotic cells are phagocytosed and thus cleared from circulating blood. Triggers of eryptosis include increase of cytosolic Ca2+ activity, formation of PGE(2), oxidative stress and excessive cell shrinkage. Erythrocyte Ca2+ activity was estimated from Fluo3 fluorescence, phosphatidylserine exposure from annexin V binding, and erythrocyte volume from forward scatter in FACS analysis. Exposure of erythrocytes to anandamide (= 2.5 microM) increased cytosolic Ca2+ activity, enhanced the percentage of annexin V binding erythrocytes and decreased erythrocyte forward scatter, effects significantly blunted in the presence of cycloxygenase inhibitors acetylsalicylic acid (50 microM) or ibuprofen (100 microM) and in the nominal absence of extracellular Ca2+. Anandamide further enhanced the stimulating effects of hypertonic (addition of 550 mM sucrose) or isotonic (isosmotic replacement of Cl- with gluconate) cell shrinkage on annexin V binding. The present observations demonstrate that anandamide increases cytosolic Ca2+ activity, thus leading to cell shrinkage and cell membrane scrambling of mature erythrocytes.

Arvanil and anandamide up-regulate CD36 expression in human peripheral blood mononuclear cells

In this study we analysed the regulation of gene expression by arvanil and anandamide in human peripheral blood mononuclear cells (PBMCs) to clarify their immunosuppressive properties. PBMCs were activated, leading to CD36 down regulation, that was normalized by arvanil and anandamide. We used microarray technology to identify a regulatory pattern associated with cell proliferation in the presence of both substances. CD3-CD28 stimulated PBMCs showed a pattern of up-regulated and down-regulated genes after treatment with these substances. We selected and analysed several genes chosen by their function in the regulation of cell proliferation. We showed a transcriptional control of the CD36 gene by arvanil and anandamide associated with an increased protein expression, thus suggesting a possible role of CD36 in anandamide and arvanil anti-inflammatory pattern.

Vanilloid receptor agonists and antagonists are mitochondrial inhibitors: how vanilloids cause non-vanilloid receptor mediated cell death

Time-lapse photomicroscopy of human H460 lung cancer cells demonstrated of the transient receptor potential V1 (TRPV1) channel agonists, (E)-capsaicin and resiniferatoxin, and the TRPV1 antagonists, capsazepine, and SB366791, were able to bring about morphological changes characteristic of apoptosis and/or necrosis. Immunoblot analysis identified immunoreactivity for the transient receptor potential V1 (TRPV1) channel in rat brain samples, but not in rat heart mitochondria or in H460 cells. In isolated rat heart mitochondria, all four ligands caused concentration-dependent decreases in oxygen consumption and mitochondrial membrane potential. (E)-Capsaicin and capsazepine evoked concentration-dependent increases and decreases, respectively, in mitochondrial hydrogen peroxide production, whilst resiniferatoxin and SB366791 were without significant effect. These data support the hypothesis that (E)-capsaicin, resiniferatoxin, capsazepine, and SB366791 are all mitochondrial inhibitors, able to activate apoptosis and/or necrosis via non-receptor mediated mechanisms, and also support the use of TRPV1 ligands as anti-cancer agents.

The acetaminophen-derived bioactive N-acylphenolamine AM404 inhibits NFAT by targeting nuclear regulatory events

AM404 is a synthetic TRPV1/CB(1) hybrid ligand with inhibitory activity on the anandamide transporter and is used for the pharmacological manipulation of the endocannabinoid system. It has been recently described that acetaminophen is metabolised in the brain to form the bioactive N-acylphenolamine AM404 and therefore, we have evaluated the effect of this metabolite in human T cells, discovering that AM404 is a potent inhibitor of TCR-mediated T-cell activation. Moreover, we found that AM404 specifically inhibited both IL-2 and TNF-alpha gene transcription and TNF-alpha synthesis in CD3/CD28-stimulated Jurkat T cells in a FAAH independent way. To further characterize the biochemical inhibitory mechanisms of AM404, we examined the signaling pathways that regulate the activation of the transcription factors NF-kappaB, NFAT and AP-1 in Jurkat cells. We found that AM404 inhibited both the binding to DNA and the transcriptional activity of endogenous NFAT and the transcriptional activity driven by the over expressed fusion protein Gal4-NFAT (1-415). However, AM404 did not affect early steps in NFAT signaling such as CD3-induced calcium mobilization and NFAT1 dephosphorylation. The NFAT inhibitory activity of AM404 seems to be quite specific since this compound did not interfere with the signaling pathways leading to AP-1 or NF-kappaB activation. These findings provide new mechanistic insights into the immunological effects of AM404 which in part could explain some of the activities ascribed to the widely used acetaminophen.

Receptor-independent actions of cannabinoids on cell membranes: Focus on endocannabinoids

Cannabinoids are a structurally diverse group of mostly lipophilic molecules that bind to cannabinoid receptors. In fact, endogenous cannabinoids (endocannabinoids) are a class of signaling lipids consisting of amides and esters of long-chain polyunsaturated fatty acids. They are synthesized from lipid precursors in plasma membranes via Ca(2+) or G-protein-dependent processes and exhibit cannabinoid-like actions by binding to cannabinoid receptors. However, endocannabinoids can produce effects that are not mediated by these receptors. In pharmacologically relevant concentrations, endocannabinoids modulate the functional properties of voltage-gated ion channels including Ca(2+) channels, Na(+) channels, various types of K(+) channels, and ligand-gated ion channels such as serotonin type 3, nicotinic acetylcholine, and glycine receptors. In addition, modulatory effects of endocannabinoids on other ion-transporting membrane proteins such as transient potential receptor-class channels, gap junctions and transporters for neurotransmitters have also been demonstrated. Furthermore, functional properties of G-protein-coupled receptors for different types of neurotransmitters and neuropeptides are altered by direct actions of endocannabinoids. Although the mechanisms of these effects are currently not clear, it is likely that these direct actions of endocannabinoids are due to their lipophilic structures. These findings indicate that additional molecular targets for endocannabinoids exist and that these targets may represent novel sites for cannabinoids to alter either the excitability of the neurons or the response of the neuronal systems. This review focuses on the results of recent studies indicating that beyond their receptor-mediated effects, endocannabinoids alter the functions of ion channels and other integral membrane proteins directly.

Iodinated N-Acylvanillamines: Potential “Multiple-Target” Anti-Inflammatory Agents Acting via the Inhibition of T-Cell Activation and Antagonism at Vanilloid TRPV1 Channels

Synthetic N-acylvanillamines were designed and developed as metabolically stable compounds with pharmacological potential in analgesia and inflammation because of their interaction with cannabinoid receptors and the vanilloid receptor (TRPV1). Here, we show that arvanil inhibits early events in T-cell receptor (TCR)-mediated T-cell activation, such as calcium mobilization and nuclear factor of activated T-cell activation, and in late events in TCR-mediated activation, such as interleukin (IL)-2 gene transcription, IL-2R expression, and cell-cycle progression. Arvanil also prevents tumor necrosis factor-alpha-induced nuclear factor-kappaB (NF-kappaB) activation by direct inhibition of IkappaBalpha degradation, NF-kappaB binding to DNA, and NF-kappaB-dependent transcription. Aromatic iodination meta to the phenolic hydroxyl (on the 6'-carbon atom) converts arvanil and olvanil from TRPV1 agonists into antagonists. However, this structural modification did not affect the immunosuppressive and proapoptotic activity of these compounds. In summary, we described here novel activities of arvanil on T-cell functions and the development of two novel inhibitors of neurogenic inflammation (6'-I-olvanil and 6'-I-arvanil) endowed with a unique combination of TRPV1 antagonistic-, immunosuppressive-, and NF-kappaB-inhibitory properties. Our findings provide new mechanistic insights into the biological activities of N-alkylvanillamines and should foster the synthesis of improved analogs amenable to pharmaceutical development as analgesic and anti-inflammatory agents.

Arvanil inhibits T lymphocyte activation and ameliorates autoimmune encephalomyelitis

This study examined the immunomodulatory effect of arvanil, a synthetic capsaicin-anandamide hybrid. Arvanil inhibits lymphocyte proliferation and IFN-gamma production. The phenotype of activated CD4+T cells treated with arvanil shows a down-regulation of T cell activation markers such as CD25, HLA-DR and CD134/OX40. Arvanil and anandamide do not induce apoptosis on CD4+T cells. Arvanil blocks the G1/S phase transition of the cell cycle in stimulated peripheral blood mononuclear cells, inducing activation of p21waf-1/cip-1 and phosphorylation of Akt/PKB. In vivo, arvanil ameliorates experimental autoimmune encephalomyelitis in the SJL/J mouse. Our findings have relevance for the use of arvanil and related compounds as a novel immunotherapeutic approach in the treatment of multiple sclerosis.