R(+)-methanandamide-induced apoptosis of human cervical carcinoma cells involves a cyclooxygenase-2-dependent pathway

Bioelectric pharmacology of cancer: A systematic review of ion channel drugs affecting the cancer phenotype

Cancer is a pernicious and pressing medical problem; moreover, it is a failure of multicellular morphogenesis that sheds much light on evolutionary developmental biology. Numerous classes of pharmacological agents have been considered as cancer therapeutics and evaluated as potential carcinogenic agents; however, these are spread throughout the primary literature. Here, we briefly review recent work on ion channel drugs as promising anti-cancer treatments and present a systematic review of the known cancer-relevant effects of 109 drugs targeting ion channels. The roles of ion channels in cancer are consistent with the importance of bioelectrical parameters in cell regulation and with the functions of bioelectric signaling in morphogenetic signals that act as cancer suppressors. We find that compounds that are well-known for having targets in the nervous system, such as voltage-gated ion channels, ligand-gated ion channels, proton pumps, and gap junctions are especially relevant to cancer. Our review suggests further opportunities for the repurposing of numerous promising candidates in the field of cancer electroceuticals.

Melanoma and cannabinoids: A possible chance for cancer treatment

The endocannabinoid system is composed by a complex and ubiquitous network of endogenous lipid ligands, enzymes for their synthesis and degradation, and receptors, which can also be stimulated by exogenous compounds, such as those derived from the Cannabis sativa. Cannabis and its bioactive compounds, including cannabinoids and non-cannabinoids, have been extensively studied in different conditions. Recent data have shown that the endocannabinoid system is responsible for maintaining the homeostasis of various skin functions such as proliferation, differentiation and release of inflammatory mediators. Because of their role in regulating these key processes, cannabinoids have been studied for the treatment of skin cancers and melanoma; their anti-tumour effects regulate skin cancer progression and are mainly related to the inhibition of tumour growth, proliferation, invasion and angiogenesis, through apoptosis and autophagy induction. This review aims at summarising the current field of research on the potential uses of cannabinoids in the melanoma field.

In Vitro Evidence of Selective Pro-Apoptotic Action of the Pure Cannabidiol and Cannabidiol-Rich Extract

Plant cannabinoids, secondary metabolites of species belonging to the Cannabis genus, can mimic the endocannabinoids' action and exert biological effects. Considering the contribution of the endocannabinoid system in cell cycle and apoptotic regulation, there is an interest in exploring the potential anti-cancer activities of natural and synthetic cannabinoids. Cannabidiol (CBD), an abundant plant cannabinoid, reveals a low affinity to cannabinoid receptors and, contrary to various cannabinoids, lacks psychoactive action. Here, we present the in vitro assessment of the pro-apoptototic potential of CBD-rich extracts of Cannabis sativa L. (eCBD) compared to purified CBD (pCBD). As demonstrated, both eCBD and pCBD decreased the viability of breast cancer cell line MDA-MB-231 and human prostate cancer cell line PC-3 in a concentration-dependent fashion. Endoplasmic reticulum stress-related apoptosis and morphological changes were induced only in low-serum conditions. Moreover, the effects of eCDB and pCDB were also assessed in non-malignant cell lines (MCF-10A and PNT2) with no alterations of viability noted, ultimately suggesting a selective action of CBD in tumor cells. The results suggest the possible involvement of reactive oxygen species in the response mechanism to eCBD and pCBD, but no clear pattern was observed. We also demonstrated significant changes in gene expression involved in apoptosis and cell cycle control upon extract treatment. Altogether, our study shows the potential of eCBD and pCBD as novel pro-apoptototic agents that can be considered promising in future preclinical and clinical testing.

Multi-charged nanoemulsion for photodynamic treatment of glioblastoma cell line in 2D and 3D in vitro models

Multi-charged nanoemulsions (NE) were designed to deliver Cannabidiol (CBD), Indocyanine green (ICG), and Protoporphyrin (PpIX) to treat glioblastoma (GBM) through Photodynamic Therapy (PDT). The phase-inversion temperature (PIT) method resulted in a highly stable NE that can be scaled easily, with a six-month shelf-life. We observed the quasi-spherical morphology of the nanoemulsions without any unencapsulated material and that 89% (± 5.5%) of the material was encapsulated. All physicochemical properties were within the expected range for a nanostructured drug delivery system, making these multi-charged nanoemulsions promising for further research and development. NE-PIC (NE-Protoporphyrin + Indocyanine + CBD) was easily internalized on GBM cells after three hours of incubation. Nanoemulsion (NE and NE-PIC) did not result in significant cytotoxicity, even for GBM or non-tumorigenic cell lines (NHF). Phototoxicity was significantly higher for the U87MG cell than the T98G cell when exposed to: visible (430 nm) and infrared (810 nm) laser light, with a difference of about 20%. From 50 mJ.cm-2, the viability of GBM cell lines decreases significantly, ranging from 65% to 85%. The NE-PIC was also effective for inhibiting cell proliferation into a 3D spheroidal GBM cell model, which is promising for mimicking the tumor cell environment. Irradiation at 810 nm was more effective in treating spheroid due to its deeper penetration in complex structures. NE-PIC has the potential as a drug delivery system for photoinactivation and photo diagnostic of GBM cell lines, taking advantage of the versatility of its active components.

The Effects of Endogenous Cannabinoids on the Mammalian Respiratory System: A Scoping Review of Cyclooxygenase-Dependent Pathways

Introduction: The endogenous cannabinoid (endocannabinoid) system is an emerging target for the treatment of chronic inflammatory disease with the potential to advance treatment for many respiratory illnesses. The varied effects of endocannabinoids across tissue types makes it imperative that we explore their physiologic impact within unique tissue targets. The aim of this scoping review is to explore the impact of endocannabinoid activity on eicosanoid production as a measure of human airway inflammation. Methods: A scoping literature review was conducted according to PRISMA-ScR (Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews) guidelines. Search strategies using MeSH terms related to cannabinoids, eicosanoids, cyclooxygenase (COX), and the respiratory system were used to query Medline, Embase, Cochrane, CINAHL, Web of Science, and Biosis Previews in December 2021. Only studies that investigated the relationship between endocannabinoids and the eicosanoid system in mammalian respiratory tissue after 1992 were included. Results: Sixteen studies were incorporated in the final qualitative review. Endocannabinoid activation increases COX-2 expression, potentially through ceramide-dependent or p38 and p42/44 Mitogen-Activated Protein Kinase pathways and is associated with a concentration-dependent increase in prostaglandin (PG)E2. Inhibitors of endocannabinoid hydrolysis found either an increase or no change in levels of PGE2 and PGD2 and decreased levels of leukotriene (LT)B4, PGI2, and thromboxane A2 (TXA2). Endocannabinoids increase bronchial epithelial cell permeability and have vasorelaxant effects in human pulmonary arteries and cause contraction of bronchi and decreased gas trapping in guinea pigs. Inhibitors of endocannabinoid hydrolysis were found to have anti-inflammatory effects on pulmonary tissue and are primarily mediated by COX-2 and activation of eicosanoid receptors. Direct agonism of endocannabinoid receptors appears to play a minor role. Conclusion: The endocannabinoid system has diverse effects on the mammalian airway. While endocannabinoid-derived PGs can have anti-inflammatory effects, endocannabinoids also produce proinflammatory conditions, such as increased epithelial permeability and bronchial contraction. These conflicting findings suggest that endocannabinoids produce a variety of effects depending on their local metabolism and receptor agonism. Elucidation of the complex interplay between the endocannabinoid and eicosanoid pathways is key to leveraging the endocannabinoid system as a potential therapeutic target for human airway disease.

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.

Use of Cannabis and Cannabinoids for Treatment of Cancer

The endocannabinoid system (ECS) is an ancient homeostasis mechanism operating from embryonic stages to adulthood. It controls the growth and development of many cells and cell lineages. Dysregulation of the components of the ECS may result in uncontrolled proliferation, adhesion, invasion, inhibition of apoptosis and increased vascularization, leading to the development of various malignancies. Cancer is the disease of uncontrolled cell division. In this review, we will discuss whether the changes to the ECS are a cause or a consequence of malignization and whether different tissues react differently to changes in the ECS. We will discuss the potential use of cannabinoids for treatment of cancer, focusing on primary outcome/care-tumor shrinkage and eradication, as well as secondary outcome/palliative care-improvement of life quality, including pain, appetite, sleep, and many more factors. Finally, we will complete this review with the chapter on sex- and gender-specific differences in ECS and response to cannabinoids, and equality of the access to treatments with cannabinoids.

Cannabinoids as anticancer drugs: current status of preclinical research

Drugs that target the endocannabinoid system are of interest as pharmacological options to combat cancer and to improve the life quality of cancer patients. From this perspective, cannabinoid compounds have been successfully tested as a systemic therapeutic option in a number of preclinical models over the past decades. As a result of these efforts, a large body of data suggests that the anticancer effects of cannabinoids are exerted at multiple levels of tumour progression via different signal transduction mechanisms. Accordingly, there is considerable evidence for cannabinoid-mediated inhibition of tumour cell proliferation, tumour invasion and metastasis, angiogenesis and chemoresistance, as well as induction of apoptosis and autophagy. Further studies showed that cannabinoids could be potential combination partners for established chemotherapeutic agents or other therapeutic interventions in cancer treatment. Research in recent years has yielded several compounds that exert promising effects on tumour cells and tissues in addition to the psychoactive Δ9-tetrahydrocannabinol, such as the non-psychoactive phytocannabinoid cannabidiol and inhibitors of endocannabinoid degradation. This review provides an up-to-date overview of the potential of cannabinoids as inhibitors of tumour growth and spread as demonstrated in preclinical studies.

Enhancement of Conventional and Photodynamic Therapy for Treatment of Cervical Cancer with Cannabidiol

Cervical cancer (CC) is the fourth most diagnosed cancer in women worldwide. Conventional treatments include surgery, chemo- and radiotherapy, however these are invasive and may cause severe side effects. Furthermore, approximately 70% of late-stage CC patients experience metastasis, due to treatment resistance and limitations. Thus, there is a dire need to investigate alternative therapeutic combination therapies. Photodynamic therapy (PDT) is an alternative CC treatment modality that has been clinically proven to treat primary CC, as well as to limit secondary metastasis. Since PDT is a non-invasive localized treatment, with fewer side effects and lessened resistance to dose repeats, it is considered far more advantageous. However, more clinical trials are required to refine its delivery and dosing, as well as improve its ability to activate specific immune responses to eradicate secondary CC spread. Cannabidiol (CBD) isolates have been shown to exert in vitro CC anticancer effects, causing apoptosis post treatment, as well as inducing specific immune responses, which obstruct tumor invasion and angiogenesis, and so hinder CC metastatic spread. This review paper discusses the current conventional and alternative PDT treatment modalities for CC, as well as their limitations over the last 10 years. It has a particular focus on the combinative administration of CBD with these treatments in order to prevent CC secondary migration and so possibly encourage future research studies to focus on this synergistic effect to eradicate CC.

Endocannabinoid System and Tumour Microenvironment: New Intertwined Connections for Anticancer Approaches

The tumour microenvironment (TME) is now recognised as a hallmark of cancer, since tumour:stroma crosstalk supports the key steps of tumour growth and progression. The dynamic co-evolution of the tumour and stromal compartments may alter the surrounding microenvironment, including the composition in metabolites and signalling mediators. A growing number of evidence reports the involvement of the endocannabinoid system (ECS) in cancer. ECS is composed by a complex network of ligands, receptors, and enzymes, which act in synergy and contribute to several physiological but also pathological processes. Several in vitro and in vivo evidence show that ECS deregulation in cancer cells affects proliferation, migration, invasion, apoptosis, and metastatic potential. Although it is still an evolving research, recent experimental evidence also suggests that ECS can modulate the functional behaviour of several components of the TME, above all the immune cells, endothelial cells and stromal components. However, the role of ECS in the tumour:stroma interplay remains unclear and research in this area is particularly intriguing. This review aims to shed light on the latest relevant findings of the tumour response to ECS modulation, encouraging a more in-depth analysis in this field. Novel discoveries could be promising for novel anti-tumour approaches, targeting the microenvironmental components and the supportive tumour:stroma crosstalk, thereby hindering tumour development.

The Impact of TRPV1 on Cancer Pathogenesis and Therapy: A Systematic Review

The transient receptor potential cation channel subfamily V member 1 (TRPV1) is a transmembrane protein that can be activated by various physical and chemical stimuli and is associated with pain transduction. In recent years, TRPV1 was discovered to play essential roles in cancer tumorigenesis and development, as TRPV1 expression levels are altered in numerous cancer cell types. Several investigations have discovered direct associations between TRPV1 and cancer cell proliferation, cell death, and metastasis. Furthermore, about two dozen TRPV1 agonists/antagonists are under clinical trial, as TRPV1 is a potential drug target for treating various diseases. Hence, more researchers are focusing on the effects of TRPV1 agonists or antagonists on cancer tumorigenesis and development. However, both agonists and antagonists may reveal anti-cancer effects, and the effect may function via or be independent of TRPV1. In this review, we provide an overview of the impact of TRPV1 on cancer cell proliferation, cell death, and metastasis, as well as on cancer therapy and the tumor microenvironment, and consider the implications of using TRPV1 agonists and antagonists for future research and potential therapeutic approaches.

Molecular Mechanism of Cannabinoids in Cancer Progression

Cannabinoids are a family of heterogeneous compounds that mostly interact with receptors eliciting several physiological effects both in the central and peripheral nervous systems and in peripheral organs. They exert anticancer action by modulating signaling pathways involved in cancer progression; furthermore, the effects induced by their use depend on both the type of tumor and their action on the components of the endocannabinoid system. This review will explore the mechanism of action of the cannabinoids in signaling pathways involved in cancer proliferation, neovascularisation, migration, invasion, metastasis, and tumor angiogenesis.

(Endo)Cannabinoids and Gynaecological Cancers

Gynaecological cancers can be primary neoplasms, originating either from the reproductive tract or the products of conception, or secondary neoplasms, representative of metastatic disease. For some of these cancers, the exact causes are unknown; however, it is recognised that the precise aetiopathogeneses for most are multifactorial and include exogenous (such as diet) and endogenous factors (such as genetic predisposition), which mutually interact in a complex manner. One factor that has been recognised to be involved in the pathogenesis and progression of gynaecological cancers is the endocannabinoid system (ECS). The ECS consists of endocannabinoids (bioactive lipids), their receptors, and metabolic enzymes responsible for their synthesis and degradation. In this review, the impact of plant-derived (Cannabis species) cannabinoids and endocannabinoids on gynaecological cancers will be discussed within the context of the complexity of the proteins that bind, transport, and metabolise these compounds in reproductive and other tissues. In particular, the potential of endocannabinoids, their receptors, and metabolic enzymes as biomarkers of specific cancers, such as those of the endometrium, will be addressed. Additionally, the therapeutic potential of targeting selected elements of the ECS as new action points for the development of innovative drugs will be presented.

Cannabinoids in Gynecological Diseases

The endocannabinoid system (ECS) is a multifunctional homeostatic system involved in many physiological and pathological conditions. The ligands of the ECS are the endo-cannabinoids, whose actions are mimicked by exogenous cannabinoids, such as phytocannabinoids and synthetic cannabinoids. Responses to the ligands of the ECS are mediated by numerous receptors like the classical cannabinoid receptors (CB₁ and CB₂) as well as ECS-related receptors, e.g., G protein-coupled receptors 18 and 55 (GPR18 and GPR55), transient receptor potential ion channels, and nuclear peroxisome proliferator-activated receptors. The ECS regulates almost all levels of female reproduction, starting with oocyte production through to parturition. Dysregulation of the ECS is associated with the development of gynecological disorders from fertility disorders to cancer. Cannabinoids that act at the ECS as specific agonists or antagonists may potentially influence dysregulation and, therefore, represent new therapeutic options for the therapy of gynecological disorders.

Modulation of the Endocannabinoid System as a Potential Anticancer Strategy

Currently, the involvement of the endocannabinoid system in cancer development and possible options for a cancer-regressive effect of cannabinoids are controversially discussed. In recent decades, a number of preclinical studies have shown that cannabinoids have an anticarcinogenic potential. Therefore, especially against the background of several legal simplifications with regard to the clinical application of cannabinoid-based drugs, an extended basic knowledge about the complex network of the individual components of the endocannabinoid system is required. The canonical endocannabinoid system consists of the endocannabinoids N-arachidonoylethanolamine (anandamide) and 2-arachidonoylglycerol as well as the G_i/o protein-coupled transmembrane cannabinoid receptors CB₁ and CB₂. As a result of extensive studies on the broader effect of these factors, other fatty acid derivatives, transmembrane and intracellular receptors, enzymes and lipid transporters have been identified that contribute to the effect of endocannabinoids when defined in the broad sense as “extended endocannabinoid system.” Among these additional components, the endocannabinoid-degrading enzymes fatty acid amide hydrolase and monoacylglycerol lipase, lipid transport proteins of the fatty acid-binding protein family, additional cannabinoid-activated G protein-coupled receptors such as GPR55, members of the transient receptor family, and peroxisome proliferator-activated receptors were identified as targets for possible strategies to combat cancer progression. Other endocannabinoid-related fatty acids such as 2-arachidonoyl glyceryl ether, O-arachidonoylethanolamine, N-arachidonoyldopamine and oleic acid amide showed an effect via cannabinoid receptors, while other compounds such as endocannabinoid-like substances exert a permissive action on endocannabinoid effects and act via alternative intracellular target structures. This review gives an overview of the modulation of the extended endocannabinoid system using the example of anticancer cannabinoid effects, which have been described in detail in preclinical studies.

Effect of endocannabinoid signalling on cell fate: life, death, differentiation and proliferation of brain cells

Cell fate events are regulated by different endogenous developmental factors such as the cell micro-environment, external or remote signals and epigenetic factors. Among the many regulatory factors, endocannabinoid-associated signalling pathways are known to conduct several of these events in the developing nervous system and in the adult brain. Interestingly, endocannabinoids exert modulatory actions in both physiological and pathological conditions. Endocannabinoid signalling can promote cell survival by acting on non-transformed brain cells (neurons, astrocytes or oligodendrocytes) and can have either a protumoural or antitumoural effect on transformed cells. Moreover, endocannabinoids are able to attenuate the detrimental effects on neurogenesis and neuroinflammation associated with ageing. Thus, the endocannabinoid system emerges as an important regulator of cell fate, controlling cell survival/cell death decisions depending on the cell type and its environment. LINKED ARTICLES: This article is part of a themed section on 8th European Workshop on Cannabinoid Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.10/issuetoc.

Targeting the endocannabinoid system as a potential anticancer approach

The endocannabinoid system is currently under intense investigation due to the therapeutic potential of cannabinoid-based drugs as treatment options for a broad variety of diseases including cancer. Besides the canonical endocannabinoid system that includes the cannabinoid receptors CB₁ and CB₂ and the endocannabinoids N-arachidonoylethanolamine (anandamide) and 2-arachidonoylglycerol, recent investigations suggest that other fatty acid derivatives, receptors, enzymes, and lipid transporters likewise orchestrate this system as components of the endocannabinoid system when defined as an extended signaling network. As such, fatty acids acting at cannabinoid receptors (e.g. 2-arachidonoyl glyceryl ether [noladin ether], N-arachidonoyldopamine) as well as endocannabinoid-like substances that do not elicit cannabinoid receptor activation (e.g. N-palmitoylethanolamine, N-oleoylethanolamine) have raised interest as anticancerogenic substances. Furthermore, the endocannabinoid-degrading enzymes fatty acid amide hydrolase and monoacylglycerol lipase, lipid transport proteins of the fatty acid binding protein family, additional cannabinoid-activated G protein-coupled receptors, members of the transient receptor potential family as well as peroxisome proliferator-activated receptors have been considered as targets of antitumoral cannabinoid activity. Therefore, this review focused on the antitumorigenic effects induced upon modulation of this extended endocannabinoid network.

Cannabinoids Modulate Neuronal Activity and Cancer by CB1 and CB2 Receptor-Independent Mechanisms

Cannabinoids include the active constituents of Cannabis or are molecules that mimic the structure and/or function of these Cannabis-derived molecules. Cannabinoids produce many of their cellular and organ system effects by interacting with the well-characterized CB1 and CB2 receptors. However, it has become clear that not all effects of cannabinoid drugs are attributable to their interaction with CB1 and CB2 receptors. Evidence now demonstrates that cannabinoid agents produce effects by modulating activity of the entire array of cellular macromolecules targeted by other drug classes, including: other receptor types; ion channels; transporters; enzymes, and protein- and non-protein cellular structures. This review summarizes evidence for these interactions in the CNS and in cancer, and is organized according to the cellular targets involved. The CNS represents a well-studied area and cancer is emerging in terms of understanding mechanisms by which cannabinoids modulate their activity. Considering the CNS and cancer together allow identification of non-cannabinoid receptor targets that are shared and divergent in both systems. This comparative approach allows the identified targets to be compared and contrasted, suggesting potential new areas of investigation. It also provides insight into the diverse sources of efficacy employed by this interesting class of drugs. Obtaining a comprehensive understanding of the diverse mechanisms of cannabinoid action may lead to the design and development of therapeutic agents with greater efficacy and specificity for their cellular targets.

The Role of Nuclear Hormone Receptors in Cannabinoid Function

Since the early 2000s, evidence has been accumulating that most cannabinoid compounds interact with the nuclear hormone family peroxisome proliferator-activated receptors (PPARs). This can be through direct binding of these compounds to PPARs, metabolism of cannabinoid to other PPAR-activating chemicals, or indirect activation of PPAR through cell signaling pathways. Delivery of cannabinoids to the nucleus may be facilitated by fatty acid-binding proteins and carrier proteins. All PPAR isoforms appear to be activated by cannabinoids, but the majority of evidence is for PPARα and γ. To date, little is known about the potential interaction of cannabinoids with other nuclear hormones. At least some (but not all) of the well-known biological actions of cannabinoids including neuroprotection, antiinflammatory action, and analgesic effects are partly mediated by PPAR-activation, often in combination with activation of the more traditional target sites of action. This has been best investigated for the endocannabinoid-like compounds palmitoylethanolamide and oleoylethanolamine acting at PPARα, and for phytocannabinoids or their derivatives activation acting at PPARγ. However, there are still many aspects of cannabinoid activation of PPAR and the role it plays in the biological and therapeutic effects of cannabinoids that remain to be investigated.

Lovastatin lactone elicits human lung cancer cell apoptosis via a COX-2/PPARγ-dependent pathway

Statins (3-hydroxy-3-methylglutaryl coenzyme A [HMG-CoA] reductase inhibitors) are well-established agents to treat hyperlipidemic states. Experimental and epidemiological evidence further implies an anticancer effect of these substances. This study investigates the mechanism underlying human lung cancer cell death by lovastatin and the role of the prostaglandin (PG)-synthesizing enzyme cyclooxygenase-2 (COX-2) in this process. In A549 and H358 lung carcinoma cells the lipophilic prodrug lovastatin lactone led to a concentration-dependent decrease of viability and induction of DNA fragmentation, whereas its HMG-CoA-inhibitory, ring-open acid form was inactive in this respect. Apoptotic cell death by lovastatin was accompanied by high intracellular levels of the lactone form, by upregulation of COX-2 mRNA and protein, as well as by increased formation of peroxisome proliferator-activated receptor γ (PPARγ)-activating PGD₂ and 15-deoxy-Δ^12,14-PGJ₂. Cells were significantly less sensitive to lovastatin-induced apoptotic cell death, when the expression or activity of COX-2 was suppressed by siRNA or by the COX-2 inhibitor NS-398. Apoptosis by lovastatin was likewise reversed by the PPARγ antagonist GW9662. Fluorescence microscopy analyses revealed a lovastatin-induced cytosol-to-nucleus translocation of PPARγ that was inhibited by NS-398. Collectively, this study demonstrates COX-2 induction and subsequent COX-2-dependent activation of PPARγ as a hitherto unknown mechanism by which lovastatin lactone induces human lung cancer cell death.

Heparin exerts anti-apoptotic effects on uterine explants by targeting the endocannabinoid system

Miscarriage caused by Gram-negative bacteria infecting the female genital tract is one of the most common complications of human pregnancy. Intraperitoneal administration of LPS to 7-days pregnant mice induces embryo resorption after 24 h. Here, we show that LPS induced apoptosis on uterine explants from 7-days pregnant mice and that CB1 receptor was involved in this effect. On the other hand, heparin has been widely used for the prevention of pregnancy loss in women with frequent miscarriage with or without thrombophilia. Besides its anticoagulant properties, heparin exerts anti-inflammatory, immunomodulatory and anti-apoptotic effects. Here, we sought to investigate whether the administration of heparin prevented LPS-induced apoptosis in uterine explants from 7-days pregnant mice. We found that heparin enhanced cell survival in LPS-treated uterine explants and that this effect was mediated by increasing uterine FAAH activity. Taken together, our results point towards a novel mechanism involved in the protective effects of heparin.

An update on PPAR activation by cannabinoids

Some cannabinoids activate the different isoforms of PPARs (α, β and γ), as shown through the use of reporter gene assays, binding studies, selective antagonists and knockout studies. Activation of all isoforms, but primarily PPARα and γ, mediates some (but not all) of the analgesic, neuroprotective, neuronal function modulation, anti-inflammatory, metabolic, anti-tumour, gastrointestinal and cardiovascular effects of some cannabinoids, often in conjunction with activation of the more traditional target sites of action such as the cannabinoid CB1 and CB2 receptors and the TRPV1 ion channel. PPARs also mediate some of the effects of inhibitors of endocannabinoid degradation or transport. Cannabinoids may be chaperoned to the PPARs by fatty acid binding proteins. The aims of this review are to update the evidence supporting PPAR activation by cannabinoids and to review the physiological responses to cannabinoids that are mediated, and not mediated, by PPAR activation.

Anandamide and decidual remodelling: COX-2 oxidative metabolism as a key regulator

Recently, endocannabinoids have emerged as signalling mediators in reproduction. It is widely accepted that anandamide (AEA) levels must be tightly regulated, and that a disturbance in AEA levels may impact decidual stability and regression. We have previously characterized the endocannabinoid machinery in rat decidual tissue and reported the pro-apoptotic action of AEA on rat decidual cells. Cyclooxygenase-2 (COX-2) is an inducible enzyme that plays a crucial role in early pregnancy, and is also a key modulator in the crosstalk between endocannabinoids and prostaglandins. On the other hand, AEA-oxidative metabolism by COX-2 is not merely a mean to inactivate its action, but it yields the formation of a new class of mediators, named prostaglandin-ethanolamides, or prostamides. In this study we found that AEA-induced apoptosis in decidual cells involves COX-2 metabolic pathway. AEA induced COX-2 expression through p38 MAPK, resulting in the formation of prostamide E2 (PME2). Our findings also suggest that AEA-induced effect is associated with NF-kB activation. Finally, we describe the involvement of PME2 in the induction of the intrinsic apoptotic pathway in rat decidual cells. Altogether, our findings highlight the role of COX-2 as a gatekeeper in the uterine environment and clarify the impact of the deregulation of AEA levels on the decidual remodelling process.

Cannabinoid Receptor-2 Regulates Embryonic Hematopoietic Stem Cell Development via Prostaglandin E2 and P-Selectin Activity

Cannabinoids (CB) modulate adult hematopoietic stem and progenitor cell (HSPCs) function, however, impact on the production, expansion, or migration of embryonic HSCs is currently uncharacterized. Here, using chemical and genetic approaches targeting CB-signaling in zebrafish, we show that CB receptor (CNR) 2, but not CNR1, regulates embryonic HSC development. During HSC specification in the aorta-gonad-mesonephros (AGM) region, CNR2 stimulation by AM1241 increased runx1;cmyb(+) HSPCs, through heightened proliferation, whereas CNR2 antagonism decreased HSPC number; FACS analysis and absolute HSC counts confirmed and quantified these effects. Epistatic investigations showed AM1241 significantly upregulated PGE2 synthesis in a Ptgs2-dependent manner to increase AGM HSCs. During the phases of HSC production and colonization of secondary niches, AM1241 accelerated migration to the caudal hematopoietic tissue (CHT), the site of embryonic HSC expansion, and the thymus; however these effects occurred independently of PGE2. Using a candidate approach for HSC migration and retention factors, P-selectin was identified as the functional target of CNR2 regulation. Epistatic analyses confirmed migration of HSCs into the CHT and thymus was dependent on CNR2-regulated P-selectin activity. Together, these data suggest CNR2-signaling optimizes the production, expansion, and migration of embryonic HSCs by modulating multiple downstream signaling pathways.

The evolving role of the endocannabinoid system in gynaecological cancer

BACKGROUND

The 'endocannabinoid system' (ECS), comprising endogenous ligands (endocannabinoids) and their regulating enzymes, together with the cannabinoid receptors, has attracted a great deal of attention because it affects not only all facets of human reproduction, from gametogenesis through to parturition and beyond, but also targets key mechanisms affecting some hallmarks of cancer. Recent evidence showing that cannabinoid receptors play a very important role in the development of malignancies outside of the reproductive organs suggests a similar role for the ECS in the establishment or continued development of gynaecological malignancy.

METHODS

Primary papers and review articles, and primary sources within these papers, up to December 2014, on the evolving role of the ECS in cancer, with a special focus on gynaecological cancers, were obtained by Medline and PubMed searches using the search terms: 'cancer', 'cannabinoid', 'endocannabinoid', 'gynaecology' and 'malignancy'. Non-English manuscripts were excluded.

RESULTS

More than 2100 sources were obtained from which only 112 were specifically important to the topic. Analysis of those articles supports a role of the ECS in gynaecological cancers but leaves many gaps in our knowledge that need to be filled. How some of the relevant receptors are activated and cause changes in cell phenotypes that progress to malignancy remains undiscovered and an area for future research. Increasing evidence suggests that malignant transformation within the female genital tract could be accompanied by deregulation of components of the ECS, acting through rather complex cannabinoid receptor-dependent and receptor-independent mechanisms.

CONCLUSIONS

The paucity of studies in this area suggests that research using animal models is needed to evaluate endocannabinoid signalling in cancer networks. Future randomized clinical studies should reveal whether endocannabinoids or their derivatives prove to be useful therapeutic targets for gynaecological and other cancers.

Induction but not inhibition of COX-2 confers human lung cancer cell apoptosis by celecoxib

The antitumorigenic mechanism of the selective cyclooxygenase-2 (COX-2) inhibitor celecoxib is still a matter of debate. Among different structurally related COX-2 inhibitors, only celecoxib was found to cause apoptosis and cell death of human lung cancer cells (IC₅₀ values of 19.96 µM [A549], 12.48 µM [H460], and 41.39 µM [H358]) that was paralleled by a time- and concentration-dependent upregulation of COX-2 and peroxisome proliferator-activated receptor γ (PPARγ) at mRNA and protein levels. Apoptotic death of celecoxib-treated cancer cells was suppressed by the PPARγ antagonist GW9662 and by siRNA targeting PPARγ and, surprisingly, also by the selective COX-2 inhibitor NS-398 and siRNA targeting COX-2. NS-398 (1 µM) was shown to suppress celecoxib-induced COX-2 activity. Among the COX-2-dependent prostaglandins (PG) induced upon celecoxib treatment, PGD₂ and 15-deoxy-Δ¹²,¹⁴-PGJ₂ were found to induce a cytosol-to-nucleus translocation of PPARγ as well as a PPARγ-dependent apoptosis. Celecoxib-elicited PPARγ translocation was inhibited by NS-398. Finally, a COX-2- and PPARγ-dependent cytotoxic action of celecoxib was proven for primary human lung tumor cells. Together, our data demonstrate a proapoptotic mechanism of celecoxib involving initial upregulation of COX-2 and PPARγ and a subsequent nuclear translocation of PPARγ by COX-2-dependent PGs.

Target-based molecular signature characteristics of cervical adenocarcinoma and squamous cell carcinoma

There is an urgent need for molecular marker studies of adenocarcinoma (AC) and squamous cell carcinoma (SCC) of the uterine cervix. This study utilized oligomicroarray and pathway analyses to characterize a transcriptomic signature with molecular networks associated with AC and SCC. A 10K oligomicroarray was used to identify potential transcripts that were differentially expressed in cervical cancers from 28 patients and common reference RNAs from 17 different normal cervixes. Molecular networks were correlated using genomics tools to globally explore cellular pathways. Gene expression levels of 46 transcripts separated cancer samples into AC and SCC groups. Genes including: KRT17, IGFBP2, CALCA and VIPR1 were differentially expressed in AC and SCC. In addition, we identified a transcriptomic signature that predicted tumor classification and progression based upon its cellular processes. The downregulated signatures for SCC were cell death of pheochromocytoma cells (P=0.0037), apoptosis of neurons (P=0.009) and damage to DNA (P=0.0038). By contrast, the upregulated molecular signatures in AC were immunological disorder (P=0.006), splenomegaly (P=0.0053) and hepatic system disorder (P=0.006). The G2/M DNA damage checkpoint regulation pathway (P=0.05) was found to be significantly linked to IGF1R as a new regulatory component of a putative cytoplasmic signaling cascade in SCC. By contrast, the antigen presenting canonical pathway (P=0.038) appeared to be linked to PPARγ in AC. Taken together, these experiments provide important new information regarding the role of molecular networks in mediating SCC and AC, possibly through two independent pathways, and contribute to provide new targets for the prevention and treatment of cervical cancer.

COX-2 and PPAR-γ confer cannabidiol-induced apoptosis of human lung cancer cells

The antitumorigenic mechanism of cannabidiol is still controversial. This study investigates the role of COX-2 and PPAR-γ in cannabidiol's proapoptotic and tumor-regressive action. In lung cancer cell lines (A549, H460) and primary cells from a patient with lung cancer, cannabidiol elicited decreased viability associated with apoptosis. Apoptotic cell death by cannabidiol was suppressed by NS-398 (COX-2 inhibitor), GW9662 (PPAR-γ antagonist), and siRNA targeting COX-2 and PPAR-γ. Cannabidiol-induced apoptosis was paralleled by upregulation of COX-2 and PPAR-γ mRNA and protein expression with a maximum induction of COX-2 mRNA after 8 hours and continuous increases of PPAR-γ mRNA when compared with vehicle. In response to cannabidiol, tumor cell lines exhibited increased levels of COX-2-dependent prostaglandins (PG) among which PGD(2) and 15-deoxy-Δ(12,14)-PGJ(2) (15d-PGJ(2)) caused a translocation of PPAR-γ to the nucleus and induced a PPAR-γ-dependent apoptotic cell death. Moreover, in A549-xenografted nude mice, cannabidiol caused upregulation of COX-2 and PPAR-γ in tumor tissue and tumor regression that was reversible by GW9662. Together, our data show a novel proapoptotic mechanism of cannabidiol involving initial upregulation of COX-2 and PPAR-γ and a subsequent nuclear translocation of PPAR-γ by COX-2-dependent PGs.

The synthetic cannabinoid R(+)WIN55,212-2 augments interferon-β expression via peroxisome proliferator-activated receptor-α

We have demonstrated that R(+)WIN55,212-2, a synthetic cannabinoid that possesses cannabimimetic properties, acts as a novel regulator of Toll-like receptor 3 (TLR3) signaling to interferon (IFN) regulatory factor 3 (IRF3) activation and IFN-β expression, and this is critical for manifesting its protective effects in a murine multiple sclerosis model. Here we investigated the role of peroxisome proliferator-activated receptor-α (PPARα) in mediating the effects of R(+)WIN55,212-2 on this pathway. Data herein demonstrate that the TLR3 agonist poly(I:C) promotes IFN-β expression and R(+)WIN55,212-2 enhances TLR3-induced IFN-β expression in a stereoselective manner via PPARα. R(+)WIN55,212-2 promotes increased transactivation and expression of PPARα. Using the PPARα antagonist GW6471, we demonstrate that R(+)WIN55,212-2 acts via PPARα to activate JNK, activator protein-1, and positive regulatory domain IV to transcriptionally regulate the IFN-β promoter. Furthermore, GW6471 ameliorated the protective effects of R(+)WIN55,212-2 during the initial phase of experimental autoimmune encephalomyelitis. Overall, these findings define PPARα as an important mediator in manifesting the effects of R(+)WIN55,212-2 on the signaling cascade regulating IFN-β expression. The study adds to our molecular appreciation of potential therapeutic effects of R(+)WIN55,212-2 in multiple sclerosis.

Arachidonoyl ethanolamide (AEA)-induced apoptosis is mediated by J-series prostaglandins and is enhanced by fatty acid amide hydrolase (FAAH) blockade

The endocannabinoid arachidonoyl ethanolamide (AEA) is a potent inducer of tumor cell apoptosis however its mechanism of cytotoxicity is unclear. A previous report from our laboratory showed that AEA induced cell death in a cyclooxygenase-2 (COX-2)-dependent manner and in this report our data indicate that AEA-induced apoptosis is mediated by COX-2 metabolic products of the J-series. In experiments conducted with JWF2 keratinocytes which over-express COX-2, AEA caused a concentration-regulated increase in J-series prostaglandin production and apoptosis. Similarly, cell treatment with exogenously added J-series prostaglandins (15-deoxy, Δ(12,14) PGJ(2) and PGJ(2)) induced apoptosis. AEA-induced apoptosis was inhibited by the antioxidant, N-acetyl cysteine, indicating that reactive oxygen species generation was required for apoptosis. Using antagonists of cannabinoid receptor 1, cannabinoid receptor 2, or transient receptor potential cation channel, subfamily V, member 1, it was observed that cannabinoid receptor inhibition did not block AEA-mediated cell death. In contrast, an inhibitor of fatty acid amide hydrolase (FAAH) potentiated AEA-induced J-series PG synthesis and apoptosis. These results suggest that the metabolism of AEA to J-series PGs regulates the induction of apoptosis in cells with elevated COX-2 levels. Our data further indicate that the proapoptotic activity of AEA can be enhanced by combining it with an inhibitor of FAAH. As such, AEA may be an effective agent to eliminate tumor cells that over-express COX-2.

International Union of Basic and Clinical Pharmacology. LXXIX. Cannabinoid receptors and their ligands: beyond CB₁ and CB₂

There are at least two types of cannabinoid receptors (CB(1) and CB(2)). Ligands activating these G protein-coupled receptors (GPCRs) include the phytocannabinoid Δ(9)-tetrahydrocannabinol, numerous synthetic compounds, and endogenous compounds known as endocannabinoids. Cannabinoid receptor antagonists have also been developed. Some of these ligands activate or block one type of cannabinoid receptor more potently than the other type. This review summarizes current data indicating the extent to which cannabinoid receptor ligands undergo orthosteric or allosteric interactions with non-CB(1), non-CB(2) established GPCRs, deorphanized receptors such as GPR55, ligand-gated ion channels, transient receptor potential (TRP) channels, and other ion channels or peroxisome proliferator-activated nuclear receptors. From these data, it is clear that some ligands that interact similarly with CB(1) and/or CB(2) receptors are likely to display significantly different pharmacological profiles. The review also lists some criteria that any novel "CB(3)" cannabinoid receptor or channel should fulfil and concludes that these criteria are not currently met by any non-CB(1), non-CB(2) pharmacological receptor or channel. However, it does identify certain pharmacological targets that should be investigated further as potential CB(3) receptors or channels. These include TRP vanilloid 1, which possibly functions as an ionotropic cannabinoid receptor under physiological and/or pathological conditions, and some deorphanized GPCRs. Also discussed are 1) the ability of CB(1) receptors to form heteromeric complexes with certain other GPCRs, 2) phylogenetic relationships that exist between CB(1)/CB(2) receptors and other GPCRs, 3) evidence for the existence of several as-yet-uncharacterized non-CB(1), non-CB(2) cannabinoid receptors; and 4) current cannabinoid receptor nomenclature.

Cyclooxygenase-2 and tissue inhibitor of matrix metalloproteinases-1 confer the antimigratory effect of cannabinoids on human trabecular meshwork cells

Cannabinoids have received considerable attention as potential antiglaucomatous drugs. Recently, prostaglandins (PG) have been suggested to contribute to this effect. Within the factors conferring the development of glaucoma, depletion of the aqueous humor outflow-regulating trabecular meshwork (TM) cells elicited by migration from the outflow system is considered to play a pivotal role. This study therefore investigates the impact of two cannabinoids, Delta(9)-tetrahydrocannabinol (THC) and R(+)-methanandamide (MA), on the migration of human TM cells and the involvement of the PG-synthesizing enzyme cyclooxygenase-2 (COX-2) and one of its potential downstream targets, the tissue inhibitor of matrix metalloproteinases-1 (TIMP-1), to this response. Using Boyden chamber assays cannabinoids were shown to elicit an antimigratory effect that was reversed by antagonists for CB(1) as well as CB(2) receptors and accompanied by upregulation of COX-2 and TIMP-1 expression and PGE(2) synthesis. Knockdown of cannabinoid-induced COX-2 or TIMP-1 expression by siRNA or inhibition of COX-2 activity by NS-398 led to a significant suppression of this antimigratory action. Migration was also diminished by the major COX-2 product PGE(2) and by recombinant TIMP-1. Experiments using selective E prostanoid (EP) receptor agonists and antagonists revealed that decreased migration by PGE(2), THC and MA was mediated via EP(2) and EP(4) receptors. Finally, the cannabinoid-mediated increases of TIMP-1 levels were abolished by NS-398, and PGE(2) was shown to elicit a concentration-dependent increase of TIMP-1. Collectively, this data demonstrate a COX-2-dependent upregulation of TIMP-1 conferring the antimigratory action of cannabinoids. A decreased migration reducing TM cell loss in glaucoma might be involved in the antiglaucomatous action of cannabinoids.

The role of prostacyclin in lung cancer

Prostanoids are bioactive lipids that interact with 7-membrane-spanning G-protein-coupled receptors on target cells to impart their biologic effects. They include prostaglandins, prostacyclin, and thromboxane. Prostanoids are widely distributed; mediate several diverse biologic effects like platelet aggregation and smooth-muscle contraction; and are known to be involved in allergies, acquired immunity, and cancer metastasis. Prostanoids have also been associated with breast and endometrial cancer promotion, and with the inhibition of melanoma. The role of prostanoids in the development of lung disease has been poorly understood. In particular, prostacyclin possesses significant anti-inflammatory and antimetastatic properties and is the main product of cyclooxygenase-2 activity in the lung. In fact, the balance of the various members of the prostanoids family, specifically the prostaglandins PGE(2) and prostacyclin (PGI(2)), seems to play an increasingly important role in the development of lung cancer. Gaining a better understanding of prostanoids and their associated pathways is critical to the future development of molecular-based and pharmaceutical treatments of lung disease.

The cannabinoid R+ methanandamide induces IL-6 secretion by prostate cancer PC3 cells

In the present study, we have investigated the effect of the cannabinoid R+ methanandamide (MET) in the androgen-resistant prostate cancer PC3 cells. MET induced a dose-dependent decrease in PC3 cell viability as well as a dose-dependent increase in the secretion of the cytokine IL-6. Looking deeper into the mechanisms involved, we found that MET-induced de novo synthesis of the lipid mediator ceramide that was blocked by the ceramide synthase inhibitor Fumonisin B1. Pre-incubation of cells with the cannabinoid receptor CB2 antagonist SR 144528 (SR2), but not the CB1 antagonist Rimonabant or the TRPV1 antagonist capsazepine, partially prevented the anti-proliferative effect, the ceramide accumulation, and the IL-6-induced secretion, suggesting a CB2 receptor-dependent mechanism. Fumonisin B1 did not have any effect in the IL-6 secretion increase induced by MET. However, even an incomplete down-regulation of (i.e., not a total silencing of) ceramide kinase expression by specific siRNA prevented the MET-induced IL-6 secretion. These results suggest that MET regulates ceramide metabolism in prostate PC3 cells which is involved in cell death as well as in IL-6 secretion. Our findings also suggest that CB2 agonists may offer a novel approach in the treatment of prostate cancer by decreasing cancer epithelial cell proliferation. However, the interaction of prostate cancer cells with their surrounding, and in particular with the immune system in vivo, needs to be further explored.