Cannabinoid receptor type 1 immunoreactivity and disease severity in human epithelial ovarian tumors

Cannabidiol attenuates lipid metabolism and induces CB1 receptor-mediated ER stress associated apoptosis in ovarian cancer cells

Ovarian cancer (OC) is the most deadly gynecological tumor. OC cells utilize cellular metabolic reprogramming to gain a survival advantage, particularly through aberrant lipid metabolic process. As the primary ingredient in exogenous cannabinoids, cannabidiol (CBD) has been confirmed to exhibit antitumor activity in preclinical studies. However, it is still unclear whether CBD can disrupt fatty acid metabolism and induce apoptosis in OC cells. In this study, we have demonstrated that CBD significantly inhibits the proliferation of OCs through a cannabinoid receptor type 1 (CB1R)-mediated manner. Fatty acid metabolic profiling and flow cytometry analysis revealed that CBD has the ability to decrease fatty acid levels and significantly suppress the transcription of genes involved in fatty acid uptake and synthesis in ES-2 cells. In addition, the analysis from RNA-seq and real-time RT-PCR revealed that CBD activated the endoplasmic reticulum (ER) stress pathway. Conversely, by supplementation with unsaturated fatty acid or blocking CB1R, ER stress or reactive oxygen species (ROS) signals with specific inhibitors could significantly relieve CBD induced, dose-dependent, ER stress associated apoptosis, G0-G1 phase arrest, and mitochondrial dysfunction. Taken collectively, these data indicate that CBD may disrupt lipid metabolism, and lead to ER stress-related apoptosis in OCs. Our findings may provide a theoretical mechanism for anti-ovarian cancer using CBD.

A Novel Non-Psychoactive Fatty Acid from a Marine Snail, Conus inscriptus, Signals Cannabinoid Receptor 1 (CB1) to Accumulate Apoptotic C16:0 and C18:0 Ceramides in Teratocarcinoma Cell Line PA1

The cannabinoid-type I (CB1) receptor functions as a double-edged sword to decide cell fate: apoptosis/survival. Elevated CB1 receptor expression is shown to cause acute ceramide accumulation to meet the energy requirements of fast-growing cancers. However, the flip side of continual CB1 activation is the initiation of a second ceramide peak that leads to cell death. In this study, we used ovarian cancer cells, PA1, which expressed CB1, which increased threefold when treated with a natural compound, bis(palmitoleic acid) ester of a glycerol (C2). This novel compound is isolated from a marine snail, Conus inscriptus, using hexane and the structural details are available in the public domain PubChem database (ID: 14275348). The compound induced two acute ceramide pools to cause G0/G1 arrest and killed cells by apoptosis. The compound increased intracellular ceramides (C:16 to 7 times and C:18 to 10 times), both of which are apoptotic inducers in response to CB1 signaling and thus the compound is a potent CB1 agonist. The compound is not genotoxic because it did not induce micronuclei formation in non-cancerous Chinese hamster ovarian (CHO) cells. Since the compound induced the cannabinoid pathway, we tested if there was a psychotropic effect in zebrafish models, however, it was evident that there were no observable neurobehavioral changes in the treatment groups. With the available data, we propose that this marine compound is safe to be used in non-cancerous cells as well as zebrafish. Thus, this anticancer compound is non-toxic and triggers the CB1 pathway without causing psychotropic effects.

Investigation of the cytotoxicity induced by cannabinoids on human ovarian carcinoma cells

Cannabinoids have been shown to induce anti-tumor activity in a variety of carcinoma cells such as breast, prostate, and brain. The aim of the present study is to investigate the anti-tumor activity of cannabinoids, CBD (cannbidiol), and CBG (cannabigerol) in ovarian carcinoma cells sensitive and resistant to chemotherapeutic drugs. Sensitive A2780 cells and resistant A2780/CP70 carcinoma cells and non-carcinoma cells were exposed to varying concentrations of CBD, CBG, carboplatin or CB1 and CB2 receptor antagonists, AM251 and AM630, respectively, alone or in combination, at different exposure times and cytotoxicity was measured by MTT assay. The mechanism of action of CBD and CB in inducing cytotoxicity was investigated involving a variety of apoptotic and cell cycle assays. Treatment with CBD and CBG selectively, dose and time dependently reduced cell viability and induced apoptosis. The effect of CBD was stronger than CBG in all cell lines tested. Both CBD and CBG induced stronger cytotoxicity than afforded by carboplatin in resistant cells. The cytotoxicity induced by CBD was not CB1 or CB2 receptor dependent in both carcinoma cells, however, CBG-induced cytotoxicity may involve CB1 receptor activity in cisplatin-resistant carcinoma cells. A synergistic effect was observed when cannabinoids at sublethal doses were combined with carboplatin in both carcinoma cells. The apoptotic event may involve loss of mitochondrial membrane potential, Annexin V, caspase 3/7, ROS activities, and cell cycle arrest. Further studies are required to investigate whether these results are translatable in the clinic. Combination therapies with conventional cancer treatments using cannabinoids are suggested.

The evolution of cannabinoid receptors in cancer

Cannabis sativa (cannabis) has been used as a therapeutic treatment for centuries treating various diseases and disorders. However, racial propaganda led to the criminalization of cannabis in the 1930s preventing opportunities to explore marijuana in therapeutic development. The increase in recreational use of cannabis further grew concern about abuse, and lead to further restrictions and distribution of cannabis in the 1970s when it was declared to be a Schedule I drug in the USA. In the late 1990s in some states, legislation assisted in legalizing the use of cannabis for medical purposes under physician supervision. As it has been proven that cannabinoids and their receptors play an essential role in the regulation of the physiological and biological processes in our bodies. The endocannabinoid system (ECS) is the complex that regulates the cell-signaling system consisting of endogenous cannabinoids (endocannabinoids), cannabinoid receptors, and the enzymes responsible for the synthesis and degradation of the endocannabinoids. The ECS along with phytocannabinoids and synthetic cannabinoids serves to be a beneficial therapeutic target in treating diseases as they play roles in cell homeostasis, cell motility, inflammation, pain-sensation, mood, and memory. Cannabinoids have been shown to inhibit proliferation, metastasis, and angiogenesis and even restore homeostasis in a variety of models of cancer in vitro and in vivo. Cannabis and its receptors have evolved into a therapeutic treatment for cancers. This article is categorized under: Cancer > Molecular and Cellular Physiology.

Cannabinoids as Prospective Anti-Cancer Drugs: Mechanism of Action in Healthy and Cancer Cells

Endogenous and exogenous cannabinoids modulate many physiological and pathological processes by binding classical cannabinoid receptors 1 (CB1) or 2 (CB2) or non-cannabinoid receptors. Cannabinoids are known to exert antiproliferative, apoptotic, anti-migratory and anti-invasive effect on cancer cells by inducing or inhibiting various signaling cascades. In this chapter, we specifically emphasize the latest research works about the alterations in endocannabinoid system (ECS) components in malignancies and cancer cell proliferation, migration, invasion, angiogenesis, autophagy, and death by cannabinoid administration, emphasizing their mechanism of action, and give a future perspective for clinical use.

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.

Therapeutic and prognostic potential of GPCRs in prostate cancer from multi-omics landscape

Prostate cancer (PRAD) is a common and fatal malignancy. It is difficult to manage clinically due to drug resistance and poor prognosis, thus creating an urgent need for novel therapeutic targets and prognostic biomarkers. Although G protein-coupled receptors (GPCRs) have been most attractive for drug development, there have been lack of an exhaustive assessment on GPCRs in PRAD like their molecular features, prognostic and therapeutic values. To close this gap, we herein systematically investigate multi-omics profiling for GPCRs in the primary PRAD by analyzing somatic mutations, somatic copy-number alterations (SCNAs), DNA methylation and mRNA expression. GPCRs exhibit low expression levels and mutation frequencies while SCNAs are more prevalent. 46 and 255 disease-related GPCRs are identified by the mRNA expression and DNA methylation analysis, respectively, complementing information lack in the genome analysis. In addition, the genomic alterations do not exhibit an observable correlation with the GPCR expression, reflecting the complex regulatory processes from DNA to RNA. Conversely, a tight association is observed between the DNA methylation and mRNA expression. The virtual screening and molecular dynamics simulation further identify four potential drugs in repositioning to PRAD. The combination of 3 clinical characteristics and 26 GPCR molecular features revealed by the transcriptome and genome exhibit good performance in predicting progression-free survival in patients with the primary PRAD, providing candidates as new biomarkers. These observations from the multi-omics analysis on GPCRs provide new insights into the underlying mechanism of primary PRAD and potential of GPCRs in developing therapeutic strategies on PRAD.

Delta-9-tetrahydrocannabinol increases vascular endothelial growth factor (VEGF) secretion through a cyclooxygenase-dependent mechanism in rat granulosa cells

While the effects of delta-9-tetrahydrocannabinol (THC), the psychoactive component of cannabis, have been studied extensively in the central nervous system, there is limited knowledge about its effects on the female reproductive system. The aim of this study was to assess the effect of THC on the expression and secretion of the angiogenic factor vascular endothelial growth factor (VEGF) in the ovary, and to determine if these effects were mediated by prostaglandins. Spontaneously immortalized rat granulosa cells (SIGCs) were exposed to THC for 24hours. Gene expression, proliferation and TNFα-induced apoptosis were evaluated in the cells and concentrations of VEGF and prostaglandin E2 (PGE₂), a known regulator of VEGF production, were determined in the media. To evaluate the role of the prostanoid pathway, cells were pre-treated with cyclooxygenase (COX) inhibitors prior to THC exposure. THC-exposed SIGCs had a significant increase in VEGF and PGE₂ secretion, along with an increase in proliferation and cell survival when challenged with an apoptosis-inducing factor. Pre-treatment with COX inhibitors reversed the THC-induced increase in both PGE₂ and VEGF secretion. Alterations in granulosa cell function, such as the ones observed after THC exposure, may impact essential ovarian processes including folliculogenesis and ovulation, which could in turn affect female reproductive health and fertility. With the ongoing increase in cannabis use and potency, further study on the impact of cannabis and its constituents on female reproductive health is required.

Cannabinoids orchestrate cross-talk between cancer cells and endothelial cells in colorectal cancer

Medical marijuana has been approved by the FDA for treating chemotherapy-induced nausea and vomiting. However, less is known about its direct effects on tumor cells and the tumor microenvironment. In this study, RNA-sequencing datasets in the NCBI GEO repository were first analyzed; upregulation of cannabinoid receptors was observed in both primary and metastatic colorectal cancer (CRC) tumor tissues. An increase of cannabinoid receptors was also found in patients with CRC, azoxymethane/dextran sulfate sodium-induced CRC and CRC metastatic mouse models. Δ⁹-Tetrahydrocannabinol (Δ⁹-THC)-induced tumor progression in both primary and metastatic mouse models and also increased angiogenesis. A human growth factor antibody array indicated that Δ⁹-THC promoted the secretion of angiogenic growth factors in CRC, leading to the induction of tube formation and migration in human-induced pluripotent stem cell-derived vascular endothelial cells. The nuclear translocation of STAT1 played important roles in Δ⁹-THC-induced angiogenesis and tumor progression. Pharmacological treatment with STAT1 antagonist or abrogation of STAT1 with CRISPR/Cas9-based strategy rescued those effects of Δ⁹-THC in CRC. This study demonstrates that marijuana might increase the risk of CRC progression and that inhibition of STAT1 is a potential strategy for attenuating these side effects.

Immunohistochemical assessment of cannabinoid type-1 receptor (CB1R) and its correlation with clinicopathological parameters in glioma

Background

Glioma is the most frequent primary brain tumor and one of the most aggressive forms of cancer. Recently, numerous studies have focused on cannabinoids as a new therapeutic approach due to their antineoplastic effects through activation of the cannabinoid receptors. This study aimed to investigate the immunohistochemical expression level of cannabinoid type-1 receptors (CB1R) in human glioma samples and evaluate its clinicopathologic significance.

Materials and methods

We analyzed the expression of CB1R in 61 paraffin-embedded glioma and 4 normal brain tissues using automated immunohistochemical assay. CB1R expression was categorized into high versus low expression levels. Statistical analyses were performed to evaluate the association between CB1R and phosphorylated extracellular signal-related kinase (p-ERK) expression levels and the clinicopathologic features of glioma.

Results

Our results showed that CB1R immunopositivity was seen in 59 of 61 cases (96.7%). CB1R was down-expressed in glioma compared to normal brain tissues. However, CB1R expression was not correlated with clinicopathological parameters except for p-ERK.

Conclusion

Our findings indicate the down-expression of CB1R in glioma tissues when compared to non-cancerous brain tissues. This change in CB1R expression in gliomas should be further tested regardless of the clinicopathological findings to provide a therapeutic advantage in glioma patients.

Cannabinoid Cancer Biology and Prevention

Plant-based, synthetic, and endogenous cannabinoids have been shown to control a diverse array of biological processes, including regulation of cell fate across cancers. Their promise as broad-based antitumor agents in preclinical models has led to the initiation of pilot clinical trials. Session 5 of the National Cancer Institute's Cannabis, Cannabinoids and Cancer Research Symposium provides an overview of this research topic. Overall, the presentations highlight cannabinoid signal transduction and specific molecular mechanisms underlying cannabinoid antitumor activity. They also demonstrate the broad-based antitumor activity of the plant-based, synthetic, and endogenous cannabinoid compounds. Importantly, evidence is presented demonstrating when cannabinoids may be contraindicated as a treatment for cancer, as in the case of human papilloma virus-meditated oropharynx cancer or potentially other p38 MAPK pathway-driven cancers. Finally, it is discussed that a key to advancing cannabinoids into the clinic is to conduct well-designed, large-scale clinical trials to determine whether cannabinoids are effective antitumor agents in cancer patients.

The Endocannabinoid System as a Pharmacological Target for New Cancer Therapies

Simple Summary

Cannabinoids have been shown to suppress tumour cell proliferation, tumour invasion, metastasis, angiogenesis, chemoresistance and epithelial-mesenchymal transition and to induce tumour cell apoptosis, autophagy and immune response. This review focuses on the current status of investigations on the impact of inhibitors of endocannabinoid-degrading enzymes on tumour growth and spread in preclinical oncology research.

Abstract

Despite the long history of cannabinoid use for medicinal and ritual purposes, an endogenous system of cannabinoid-controlled receptors, as well as their ligands and the enzymes that synthesise and degrade them, was only discovered in the 1990s. Since then, the endocannabinoid system has attracted widespread scientific interest regarding new pharmacological targets in cancer treatment among other reasons. Meanwhile, extensive preclinical studies have shown that cannabinoids have an inhibitory effect on tumour cell proliferation, tumour invasion, metastasis, angiogenesis, chemoresistance and epithelial-mesenchymal transition (EMT) and induce tumour cell apoptosis and autophagy as well as immune response. Appropriate cannabinoid compounds could moreover be useful for cancer patients as potential combination partners with other chemotherapeutic agents to increase their efficacy while reducing unwanted side effects. In addition to the direct activation of cannabinoid receptors through the exogenous application of corresponding agonists, another strategy is to activate these receptors by increasing the endocannabinoid levels at the corresponding pathological hotspots. Indeed, a number of studies accordingly showed an inhibitory effect of blockers of the endocannabinoid-degrading enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) on tumour development and spread. This review summarises the relevant preclinical studies with FAAH and MAGL inhibitors compared to studies with cannabinoids and provides an overview of the regulation of the endocannabinoid system in cancer.

Pros and Cons of the Cannabinoid System in Cancer: Focus on Hematological Malignancies

The endocannabinoid system (ECS) is a composite cell-signaling system that allows endogenous cannabinoid ligands to control cell functions through the interaction with cannabinoid receptors. Modifications of the ECS might contribute to the pathogenesis of different diseases, including cancers. However, the use of these compounds as antitumor agents remains debatable. Pre-clinical experimental studies have shown that cannabinoids (CBs) might be effective for the treatment of hematological malignancies, such as leukemia and lymphoma. Specifically, CBs may activate programmed cell death mechanisms, thus blocking cancer cell growth, and may modulate both autophagy and angiogenesis. Therefore, CBs may have significant anti-tumor effects in hematologic diseases and may synergistically act with chemotherapeutic agents, possibly also reducing chemoresistance. Moreover, targeting ECS might be considered as a novel approach for the management of graft versus host disease, thus reducing some symptoms such as anorexia, cachexia, fatigue, anxiety, depression, and neuropathic pain. The aim of the present review is to collect the state of the art of CBs effects on hematological tumors, thus focusing on the essential topics that might be useful before moving into the clinical practice.

Can Cannabidiol Affect the Efficacy of Chemotherapy and Epigenetic Treatments in Cancer?

The success of cannabinoids with chronic neuropathic pain and anxiety has been demonstrated in a multitude of studies. With the high availability of a non-intoxicating compound, cannabidiol (CBD), an over-the-counter medication, has generated heightened interest in its use in the field of oncology. This review focuses on the widespread therapeutic potential of CBD with regard to enhanced wound healing, lowered toxicity profiles of chemotherapeutics, and augmented antitumorigenic effects. The current literature is sparse with regard to determining the clinically relevant concentrations of CBD given the biphasic nature of the compound’s response. Therefore, there is an imminent need for further dose-finding studies in order to determine the optimal dose of CBD for both intermittent and regular users. We address the potential influence of regular or occasional CBD usage on therapeutic outcomes in ovarian cancer patients. Additionally, as the development of chemoresistance in ovarian cancer results in treatment failure, the potential for CBD to augment the efficacy of conventional chemotherapeutic and epigenetic drugs is a topic of significant importance. Our review is focused on the widespread therapeutic potential of CBD and whether or not a synergistic role exists in combination with epigenetic and classic chemotherapy medications.

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.

3-Hydroxypropane-1,2-Diyl Dipalmitoleate-A Natural Compound with Dual Roles (CB1 Agonist/FAAH1 Blocker) in Inhibiting Ovarian Cancer Cell Line

Though it was once known that upregulated Cannabinoid Receptor (CB1) and downregulated Fatty Acid Amide Hydrolase (FAAH1) are associated with tumour aggressiveness and metastasis, it is now clear that upregulated CB1 levels more than a certain point cause accumulation of ceramide and directs cells to apoptosis. Hence, CB1 analogues/FAAH1 blockers are explored widely as anticancer drugs. There are reports on CB1-agonists and FAAH1-blockers separately, however, dual activities along with ovarian cancer-specific links are not established for any natural compound. With this setting, we describe for the first time the isolation of 3-hydroxypropane-1,2-diyl dipalmitoleate (564.48 Da) from a marine snail, Conus inscriptus, which binds to both CB1 and FAAH1 (glide energies: −70.61 and −30.52 kcal/mol, respectively). MD simulations indicate stable compound–target interaction for a minimum of 50 nanoseconds with relative invariabilities in R_g. The compound inhibited ovarian cancer cell line, PA1 at 1.7 μM. Structural and chemical interpretation of the compound (C2) was done using FT-IR, GC-MS, ESI-MS, ¹H and ¹³C-NMR (1 and 2D). Furthermore, a probable route for gram-scale synthesis of C2 is hinted herein. With the available preliminary data, molecular mechanisms involving dual roles for this potent molecule must be elucidated to understand the possibilities of usage as an anticancer drug.

(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.

The Interplay between Cancer Biology and the Endocannabinoid System-Significance for Cancer Risk, Prognosis and Response to Treatment

The various components of the endocannabinoid system (ECS), such as the cannabinoid receptors (CBRs), cannabinoid ligands, and the signalling network behind it, are implicated in several tumour-related states, both as favourable and unfavourable factors. This review analyses the ECS's complex involvement in the susceptibility to cancer, prognosis, and response to treatment, focusing on its relationship with cancer biology in selected solid cancers (breast, gastrointestinal, gynaecological, prostate cancer, thoracic, thyroid, CNS tumours, and melanoma). Changes in the expression and activation of CBRs, as well as their ability to form distinct functional heteromers affect the cell's tumourigenic potential and their signalling properties, leading to pharmacologically different outcomes. Thus, the same ECS component can exert both protective and pathogenic effects in different tumour subtypes, which are often pathologically driven by different biological factors. The use of endogenous and exogenous cannabinoids as anti-cancer agents, and the range of effects they might induce (cell death, regulation of angiogenesis, and invasion or anticancer immunity), depend in great deal on the tumour type and the specific ECS component that they target. Although an attractive target, the use of ECS components in anti-cancer treatment is still interlinked with many legal and ethical issues that need to be considered.

Cannabidiol (CBD) as a Promising Anti-Cancer Drug

Recently, cannabinoids, such as cannabidiol (CBD) and Δ9 -tetrahydrocannabinol (THC), have been the subject of intensive research and heavy scrutiny. Cannabinoids encompass a wide array of organic molecules, including those that are physiologically produced in humans, synthesized in laboratories, and extracted primarily from the Cannabis sativa plant. These organic molecules share similarities in their chemical structures as well as in their protein binding profiles. However, pronounced differences do exist in their mechanisms of action and clinical applications, which will be briefly compared and contrasted in this review. The mechanism of action of CBD and its potential applications in cancer therapy will be the major focus of this review article.

Anti-Cancer Potential of Cannabinoids, Terpenes, and Flavonoids Present in Cannabis

In recent years, and even more since its legalization in several jurisdictions, cannabis and the endocannabinoid system have received an increasing amount of interest related to their potential exploitation in clinical settings. Cannabinoids have been suggested and shown to be effective in the treatment of various conditions. In cancer, the endocannabinoid system is altered in numerous types of tumours and can relate to cancer prognosis and disease outcome. Additionally, cannabinoids display anticancer effects in several models by suppressing the proliferation, migration and/or invasion of cancer cells, as well as tumour angiogenesis. However, the therapeutic use of cannabinoids is currently limited to the treatment of symptoms and pain associated with chemotherapy, while their potential use as cytotoxic drugs in chemotherapy still requires validation in patients. Along with cannabinoids, cannabis contains several other compounds that have also been shown to exert anti-tumorigenic actions. The potential anti-cancer effects of cannabinoids, terpenes and flavonoids, present in cannabis, are explored in this literature review.

PLGA Nanoparticles for the Intraperitoneal Administration of CBD in the Treatment of Ovarian Cancer: In Vitro and In Ovo Assessment

The intraperitoneal administration of chemotherapeutics has emerged as a potential route in ovarian cancer treatment. Nanoparticles as carriers for these agents could be interesting by increasing the retention of chemotherapeutics within the peritoneal cavity. Moreover, nanoparticles could be internalised by cancer cells and let the drug release near the biological target, which could increase the anticancer efficacy. Cannabidiol (CBD), the main nonpsychotropic cannabinoid, appears as a potential anticancer drug. The aim of this work was to develop polymer nanoparticles as CBD carriers capable of being internalised by ovarian cancer cells. The drug-loaded nanoparticles (CBD-NPs) exhibited a spherical shape, a particle size around 240 nm and a negative zeta potential (-16.6 ± 1.2 mV). The encapsulation efficiency was high, with values above 95%. A controlled CBD release for 96 h was achieved. Nanoparticle internalisation in SKOV-3 epithelial ovarian cancer cells mainly occurred between 2 and 4 h of incubation. CBD antiproliferative activity in ovarian cancer cells was preserved after encapsulation. In fact, CBD-NPs showed a lower IC₅₀ values than CBD in solution. Both CBD in solution and CBD-NPs induced the expression of PARP, indicating the onset of apoptosis. In SKOV-3-derived tumours formed in the chick embryo model, a slightly higher-although not statistically significant-tumour growth inhibition was observed with CBD-NPs compared to CBD in solution. To sum up, poly-lactic-co-glycolic acid (PLGA) nanoparticles could be a good strategy to deliver CBD intraperitoneally for ovarian cancer treatment.

Cannabinoids Promote Progression of HPV-Positive Head and Neck Squamous Cell Carcinoma via p38 MAPK Activation

PURPOSE

Human papillomavirus (HPV)-related head and neck squamous cell carcinoma (HNSCC) is associated with daily marijuana use and is also increasing in parallel with increased marijuana use in the United States. Our study is designed to define the interaction between cannabinoids and HPV-positive HNSCC.

EXPERIMENTAL DESIGN

The expression of cannabinoid receptors CNR1 and CNR2 was analyzed using The Cancer Genome Atlas (TCGA) HNSCC data. We used agonists, antagonists, siRNAs, or shRNA-based models to explore the roles of CNR1 and CNR2 in HPV-positive HNSCC cell lines and animal models. Cannabinoid downstream pathways involved were determined by Western blotting and analyzed in a primary HPV HNSCC cohort with single-sample gene set enrichment analysis (ssGSEA) and the OncoGenome Positioning System (Onco-GPS).

RESULTS

In TCGA cohort, the expression of CNR1 and CNR2 was elevated in HPV-positive HNSCC compared with HPV-negative HNSCC, and knockdown of CNR1/CNR2 expression inhibited proliferation in HPV-positive HNSCC cell lines. Specific CNR1 and CNR2 activation as well as nonselective cannabinoid receptor activation in cell lines and animal models promoted cell growth, migration, and inhibited apoptosis through p38 MAPK pathway activation. CNR1/CNR2 antagonists suppressed cell proliferation and migration and induced apoptosis. Using whole-genome expression analysis in a primary HPV HNSCC cohort, we identified specific p38 MAPK pathway activation signature in tumors from HPV HNSCC patients with objective measurement of concurrent cannabinoid exposure.

CONCLUSIONS

Cannabinoids can promote progression of HPV-positive HNSCC through p38 MAPK pathway activation.

The (endo)cannabinoid signaling in female reproduction: What are the latest advances?

Cannabis extracts like marijuana have the highest consumption rate worldwide. Yet, their societal acceptance as recreational and therapeutic drugs could represent a serious hazard to female human reproduction, because cannabis ingredients [termed (phyto)cannabinoids] can perturb an endogenous system of lipid signals known as endocannabinoids. Accumulated evidence on animal models and humans has demonstrated a crucial role of these endogenous signals on different aspects of female reproduction, where they act through an ensamble of proteins that synthesize, transport, degrade and traffic them. Several reports have recently evidenced the potential role of endocannabinoids as biomarkers of female infertility for disease treatment and prevention, as well as their possible epigenetic effects on pregnancy. The purpose of this review is to provide an update of data collected in the last decade on the effects of cannabinoids and endocannabinoids on female reproductive events, from development and maturation of follicles and oocytes, to fertilization, oviductal transport, implantation and labor. In this context, a particular attention has been devoted to the ovary and the production of fertilizable oocytes, because recent studies have addressed this hot topic with conflicting results among species.

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.

The role of the endocannabinoid system in female reproductive tissues

There has been increasing interest in the role of endocannabinoids as critical modulators of the female reproductive processes. Endocannabinoids are natural ligands of cannabinoid, vanilloid, and peroxisome proliferator-activated receptors. Together with their receptors, enzymes and downstream signaling targets, they form the endocannabinoid system (ECS). While the ECS is known to modulate pain and neurodevelopment, it is also known to impact the female reproductive system where it affects folliculogenesis, oocyte maturation, and ovarian endocrine secretion. In addition, the ECS affects oviductal embryo transport, implantation, uterine decidualization and placentation. There is a complex interplay between the ECS and the hypothalamic-pituitary-ovarian axis, and an intricate crosstalk between the ECS and steroid hormone production and secretion. Exogenous cannabinoids, derived from plants such as Cannabis sativa, are also ligands for cannabinoid receptors. These have been shown to have clinical outcomes related to ECS dysregulation, including multiple sclerosis, Alzheimer's disease, and amyotrophic lateral sclerosis, along with adverse effects on female reproduction. The aim of this review is to describe and discuss data from human, animal, and in vitro studies that support the important role of the endocannabinoid system in female reproductive tissues and processes. In particular, we will discuss some of the mechanisms by which endocannabinoid signaling can affect ovarian function in both physiological and pathophysiological states.

Cannabis sativa L. and Nonpsychoactive Cannabinoids: Their Chemistry and Role against Oxidative Stress, Inflammation, and Cancer

In the last decades, a lot of attention has been paid to the compounds present in medicinal Cannabis sativa L., such as Δ⁹-tetrahydrocannabinol (Δ⁹-THC) and cannabidiol (CBD), and their effects on inflammation and cancer-related pain. The National Cancer Institute (NCI) currently recognizes medicinal C. sativa as an effective treatment for providing relief in a number of symptoms associated with cancer, including pain, loss of appetite, nausea and vomiting, and anxiety. Several studies have described CBD as a multitarget molecule, acting as an adaptogen, and as a modulator, in different ways, depending on the type and location of disequilibrium both in the brain and in the body, mainly interacting with specific receptor proteins CB₁ and CB₂. CBD is present in both medicinal and fibre-type C. sativa plants, but, unlike Δ⁹-THC, it is completely nonpsychoactive. Fibre-type C. sativa (hemp) differs from medicinal C. sativa, since it contains only few levels of Δ⁹-THC and high levels of CBD and related nonpsychoactive compounds. In recent years, a number of preclinical researches have been focused on the role of CBD as an anticancer molecule, suggesting CBD (and CBD-like molecules present in the hemp extract) as a possible candidate for future clinical trials. CBD has been found to possess antioxidant activity in many studies, thus suggesting a possible role in the prevention of both neurodegenerative and cardiovascular diseases. In animal models, CBD has been shown to inhibit the progression of several cancer types. Moreover, it has been found that coadministration of CBD and Δ⁹-THC, followed by radiation therapy, causes an increase of autophagy and apoptosis in cancer cells. In addition, CBD is able to inhibit cell proliferation and to increase apoptosis in different types of cancer models. These activities seem to involve also alternative pathways, such as the interactions with TRPV and GRP55 receptor complexes. Moreover, the finding that the acidic precursor of CBD (cannabidiolic acid, CBDA) is able to inhibit the migration of breast cancer cells and to downregulate the proto-oncogene c-fos and the cyclooxygenase-2 (COX-2) highlights the possibility that CBDA might act on a common pathway of inflammation and cancer mechanisms, which might be responsible for its anticancer activity. In the light of all these findings, in this review we explore the effects and the molecular mechanisms of CBD on inflammation and cancer processes, highlighting also the role of minor cannabinoids and noncannabinoids constituents of Δ⁹-THC deprived hemp.

Identification of Genes and Pathways Involved in Ovarian Epithelial Cancer by Bioinformatics Analysis

Ovarian epithelial cancer (OEC) is an often fatal disease with poor prognosis in women with high-stage disease. In contrast, ovarian low malignant potential (LMP) tumors with favorable prognosis behaves as a disease between benign and malignant tumors. The involved genes and pathways between benign-like LMP and aggressive OEC are largely unknown. This study integrated two cohorts profile datasets to investigate the potential key candidate genes and pathways associated with OEC. Gene expression in two datasets (GSE9891 and GSE12172), including 327 OECs and 48 LMP tumors, were analyzed. 559 differentially expressed genes were found to overlap, 251 up-regulated and 308 down-regulated. Subsequently, analysis of gene ontology, signaling pathway enrichment and protein-protein interaction (PPI) network was performed. Gene ontology analysis clustered the up-regulated and down-regulated genes based on significant enrichment. 282 nodes/ differentially expressed genes (DEGs) were identified from DEGs PPI network complex, and two most significant k-clique modules were identified from PPI. In a summary, using integrated bioinformatics analysis, we are able to identify biomarkers potentially significant in the pathogenesis of OEC, which can improve our understanding of the cause and molecular events. These candidate genes and pathways could be used for further confirmation, and lead to better disease diagnose and therapy.

Insights into the effects of the endocannabinoid system in cancer: a review

In the last few decades, the endocannabinoid system has attracted a great deal of interest in terms of its applications to clinical medicine. In particular, its applications in cancer probably represent one of the therapeutic areas with most promise. On the one hand, expression of the endocannabinoid system is altered in numerous types of tumours, compared to healthy tissue, and this aberrant expression has been related to cancer prognosis and disease outcome, suggesting a role of this system in tumour growth and progression that depends on cancer type. On the other hand, cannabinoids exert an anticancer activity by inhibiting the proliferation, migration and/or invasion of cancer cells and also tumour angiogenesis. However, some cannabinoids, at lower concentrations, may increase tumour proliferation, inducing cancer growth. Enough data has been provided to consider the endocannabinoid system as a new therapeutic target in cancer, although further studies to fully establish the effect of cannabinoids on tumour progression are still needed.

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.

Gαs signalling of the CB1 receptor and the influence of receptor number

BACKGROUND AND PURPOSE

CB1 receptor signalling is canonically mediated through inhibitory Gαi proteins, but occurs through other G proteins under some circumstances, Gαs being the most characterized secondary pathway. Determinants of this signalling switch identified to date include Gαi blockade, CB1 /D2 receptor co-stimulation, CB1 agonist class and cell background. Hence, we examined the effects of receptor number and different ligands on CB1 receptor signalling.

EXPERIMENTAL APPROACH

CB1 receptors were expressed in HEK cells at different levels, and signalling characterized for cAMP by real-time BRET biosensor -CAMYEL - and for phospho-ERK by AlphaScreen. Homogenate and whole cell radioligand binding assays were performed to characterize AM6544, a novel irreversible CB1 receptor antagonist.

KEY RESULTS

In HEK cells expressing high levels of CB1 receptors, agonist treatment stimulated cAMP, a response not known to be mediated by receptor number. Δ9 -THC and BAY59-3074 increased cAMP only in high-expressing cells pretreated with pertussis toxin, and agonists demonstrated more diverse signalling profiles in the stimulatory pathway than the canonical inhibitory pathway. Pharmacological CB1 receptor knockdown and Gαi 1 supplementation restored canonical Gαi signalling to high-expressing cells. Constitutive signalling in both low- and high-expressing cells was Gαi -mediated.

CONCLUSION AND IMPLICATIONS

CB1 receptor coupling to opposing G proteins is determined by both receptor and G protein expression levels, which underpins a mechanism for non-canonical signalling in a fashion consistent with Gαs signalling. CB1 receptors mediate opposite consequences in endpoints such as tumour viability depending on expression levels; our results may help to explain such effects at the level of G protein coupling.

Cannabinoids as Anticancer Drugs

The endocannabinoid system encompassing cannabinoid receptors, endogenous receptor ligands (endocannabinoids), as well as enzymes conferring the synthesis and degradation of endocannabinoids has emerged as a considerable target for pharmacotherapeutical approaches of numerous diseases. Besides palliative effects of cannabinoids used in cancer treatment, phytocannabinoids, synthetic agonists, as well as substances that increase endogenous endocannabinoid levels have gained interest as potential agents for systemic cancer treatment. Accordingly, cannabinoid compounds have been reported to inhibit tumor growth and spreading in numerous rodent models. The underlying mechanisms include induction of apoptosis, autophagy, and cell cycle arrest in tumor cells as well as inhibition of tumor cell invasion and angiogenic features of endothelial cells. In addition, cannabinoids have been shown to suppress epithelial-to-mesenchymal transition, to enhance tumor immune surveillance, and to support chemotherapeutics' effects on drug-resistant cancer cells. However, unwanted side effects include psychoactivity and possibly pathogenic effects on liver health. Other cannabinoids such as the nonpsychoactive cannabidiol exert a comparatively good safety profile while exhibiting considerable anticancer properties. So far experience with anticarcinogenic effects of cannabinoids is confined to in vitro studies and animal models. Although a bench-to-bedside conversion remains to be established, the current knowledge suggests cannabinoid compounds to serve as a group of drugs that may offer significant advantages for patients suffering from cancer diseases. The present review summarizes the role of the endocannabinoid system and cannabinoid compounds in tumor progression.

Spatial distribution of cannabinoid receptor 1 and fatty acid amide hydrolase in the cat ovary and oviduct

Involvement of the endocannabinoid system in female reproduction has been extensively described in humans with the cognate receptors and ligands being found in the ovaries and genital tract. In human, an imbalance of the endocannabinoid system is linked with both ectopic pregnancy and infertility. In bovine species anandamide levels regulate aspects of sperm-oviduct interaction. Here we report the immunohistochemical distribution of cannabinoid receptor 1 (CB1R) and fatty acid amide hydrolase (FAAH) in cat ovary and oviduct, using paraffin-embedded tissue samples and commercially available antibodies. We found a differential expression of both CB1R and FAAH during different stages of ovarian function and in the oviduct. CB1R was detected only in tertiary follicle granulosa cells while more immature follicles were negative. FAAH was instead found in ovarian pre-antral follicles, the oocyte cytoplasm, and in granulosa cells of primary, secondary and tertiary follicles. Secondary and tertiary follicles were also FAAH immunoreactive. Luteal cells were immunopositive for both CB1R and FAAH. Because CBR1 in oviduct was found only in ciliated cells, it might represent a specific marker at least in cats. In contrast, FAAH immunoreactivity was observed in both ciliated and non-ciliated cells. The present study may thus serve as the starting point for further investigations on the role of the endocannabinoid system in cat reproduction. Additional work will be needed to assess whether the morphological distribution of CB1R and FAAH changes in different conditions such as pre-pubertal age, follicular phase of the sexual cycle and pregnancy.

Endocannabinoid system and anticancer properties of cannabinoids

Cannabinoids impact human body by binding to cannabinoids receptors (CB1 and CB2). The two main phytocannabinoids are Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD). THC interacts with CB1 receptors occurring in central nervous system and is responsible for psychoactive properties of marijuana. CBD has low affinity to CB1 receptor, has no psychoactive characteristics and its medical applications can be wider. CB receptors are part of a complex machinery involved in regulation of many physiological processes – endocannabinoid system. Cannabinoids have found some applications in palliative medicine, but there are many reports concerning their anticancer affects. Agonists of CB1 receptors stimulate accumulation of ceramides in cancer cells, stress of endoplasmic reticulum (ER stress) and, in turn, apoptosis. Effects of cannabinoids showing low affinity to CB receptors is mediated probably by induction of reactive oxygen species production.  Knowledge of antitumor activity of cannabinoids is still based only on preclinical studies and there is a necessity to conduct more experiments to assess the real potential of these compounds.

Phyto-, endo- and synthetic cannabinoids: promising chemotherapeutic agents in the treatment of breast and prostate carcinomas

INTRODUCTION

The term 'cannabinoids' designates a family of compounds with activity upon cannabinoid receptors. Cannabinoids are classified in three groups: phytocannabinoids, endocannabinoids, and the synthetic analogues of both groups. They have become a promising tool in the treatment of cancer disease, not only as palliative agents, but also as antitumor drugs, due to their ability to inhibit the proliferation, adhesion, migration, invasion, and angiogenesis of tumour cells. Two of the cancers where they have shown high anticancer activity are breast and prostate tumours. Despite this potential clinical interest, several studies have also reported that cannabinoids can stimulate the proliferation of cancer cells at very low concentrations. Areas covered: The aim of this review is to evaluate the promising chemotherapeutic utility of phytocannabinoids, endocannabinoids, and synthetic cannabinoids in breast and prostate cancer. Expert opinion: Cannabinoids, in particular the non-psychoactive CBD, may be promising tools in combination therapy for breast and prostate cancer, due to their direct antitumor effects, their ability to improve the efficacy of conventional antitumor drugs and their usefulness as palliative treatment. Nevertheless, deeper studies to fully establish the mechanisms responsible for their antitumour and pro-tumour properties and their formulation in efficient delivery systems remain to be established.

Endocannabinoid system as a regulator of tumor cell malignancy - biological pathways and clinical significance

The endocannabinoid system (ECS) comprises cannabinoid receptors (CBs), endogenous cannabinoids, and enzymes responsible for their synthesis, transport, and degradation of (endo)cannabinoids. To date, two CBs, CB1 and CB2, have been characterized; however, orphan G-protein-coupled receptor GPR55 has been suggested to be the third putative CB. Several different types of cancer present abnormal expression of CBs, as well as other components of ECS, and this has been shown to correlate with the clinical outcome. Although most effects of (endo)cannabinoids are mediated through stimulation of classical CBs, they also interact with several molecules, either prosurvival or proapoptotic molecules. It should be noted that the mode of action of exogenous cannabinoids differs significantly from that of endocannabinoid and results from the studies on their activity both in vivo and in vitro could not be easily compared. This review highlights the main signaling pathways involved in the antitumor activity of cannabinoids and the influence of their activation on cancer cell biology. We also discuss changes in the expression pattern of the ECS in various cancer types that have an impact on disease progression and patient survival. A growing amount of experimental data imply possible exploitation of cannabinoids in cancer therapy.

Antitumorigenic targets of cannabinoids - current status and implications

INTRODUCTION

Molecular structures of the endocannabinoid system have gained interest as potential pharmacotherapeutical targets for systemic cancer treatment.

AREAS COVERED

The present review covers the contribution of the endocannabinoid system to cancer progression. Particular focus will be set on the accumulating preclinical data concerning antimetastatic, anti-invasive and anti-angiogenic mechanisms induced by cannabinoids.

EXPERT OPINION

The main goal of targeting endocannabinoid structures for systemic anticancer treatment is the comparatively good safety profile of cannabinoid compounds. In addition, antitumorigenic mechanisms of cannabinoids are not restricted to a single molecular cascade but involve multiple effects on various levels of cancer progression such as angiogenesis and metastasis. Particularly the latter effect has gained interest for pharmacological interventions. Thus, drugs aiming at the endocannabinoid system may represent potential 'antimetastatics' for an upgrade of a future armamentarium against cancer diseases.

Cannabinoid receptor CB1 regulates STAT3 activity and its expression dictates the responsiveness to SR141716 treatment in human glioma patients' cells

Herein we show that a majority of human brain tumor samples and cell lines over-expressed cannabinoid receptor CB1 as compared to normal human astrocytes (NHA), while uniformly expressed low levels of CB2. This finding prompted us to investigate the therapeutic exploitation of CB1 inactivation by SR141716 treatment, with regard to its direct and indirect cell-mediated effects against gliomas. Functional studies, using U251MG glioma cells and primary tumor cell lines derived from glioma patients expressing different levels of CB1, highlighted SR141716 efficacy in inducing apoptosis via G1 phase stasis and block of TGF-β1 secretion through a mechanism that involves STAT3 inhibition. According to the multivariate role of STAT3 in the immune escape too, interestingly SR141716 lead also to the functional and selective expression of MICA/B on the surface of responsive malignant glioma cells, but not on NHA. This makes SR141716 treated-glioma cells potent targets for allogeneic NK cell-mediated recognition through a NKG2D restricted mechanism, thus priming them for NK cell antitumor reactivity. These results indicate that CB1 and STAT3 participate in a new oncogenic network in the complex biology of glioma and their expression levels in patients dictate the efficacy of the CB1 antagonist SR141716 in multimodal glioma destruction.

The endocannabinoid system in the human granulosa cell line KGN

Ovarian steroidogenesis is embedded in a sensitive network of regulatory mechanisms crucial for human fertility. The endocannabinoid system (ECS) represents an intrinsic modulating system involved in the regulation of endocrine functions. In the present study we characterized the ECS in the human granulosa cell line KGN and its impact on gonadotropin sensitivity and steroid hormone synthesis under basal and FSH-stimulated conditions. Expression studies were performed and estradiol was measured. CB1, CB2, DAGL, FAAH, GPR55, MAGL, NAPE-PLD and TRPV1 were expressed without FSH-dependent effects. Treatment with selective cannabinoid receptor agonists reduced basal but not FSH-stimulated estradiol and CYP19. Progesterone was not altered by ECS manipulation. CB1 agonist changed the expression of miRNAs associated with granulosa cell function, e.g. miR-23a, miR-24, miR-181a and miR-320a. Present data indicate a modulating role of the intrinsic ovarian ECS in the regulation of estradiol synthesis.

The use of cannabinoids as anticancer agents

It is well-established that cannabinoids exert palliative effects on some cancer-associated symptoms. In addition evidences obtained during the last fifteen years support that these compounds can reduce tumor growth in animal models of cancer. Cannabinoids have been shown to activate an ER-stress related pathway that leads to the stimulation of autophagy-mediated cancer cell death. In addition, cannabinoids inhibit tumor angiogenesis and decrease cancer cell migration. The mechanisms of resistance to cannabinoid anticancer action as well as the possible strategies to develop cannabinoid-based combinational therapies to fight cancer have also started to be explored. In this review we will summarize these observations (that have already helped to set the bases for the development of the first clinical studies to investigate the potential clinical benefit of using cannabinoids in anticancer therapies) and will discuss the possible future avenues of research in this area.

Potential upstream regulators of cannabinoid receptor 1 signaling in prostate cancer: a Bayesian network analysis of data from a tissue microarray

BACKGROUND

The endocannabinoid system regulates cancer cell proliferation, and in prostate cancer a high cannabinoid CB1 receptor expression is associated with a poor prognosis. Down-stream mediators of CB1 receptor signaling in prostate cancer are known, but information on potential upstream regulators is lacking.

RESULTS

Data from a well-characterized tumor tissue microarray were used for a Bayesian network analysis using the max-min hill-climbing method. In non-malignant tissue samples, a directionality of pEGFR (the phosphorylated form of the epidermal growth factor receptor) → CB1 receptors were found regardless as to whether the endocannabinoid metabolizing enzyme fatty acid amide hydrolase (FAAH) was included as a parameter. A similar result was found in the tumor tissue, but only when FAAH was included in the analysis. A second regulatory pathway, from the growth factor receptor ErbB2 → FAAH was also identified in the tumor samples. Transfection of AT1 prostate cancer cells with CB1 receptors induced a sensitivity to the growth-inhibiting effects of the CB receptor agonist CP55,940. The sensitivity was not dependent upon the level of receptor expression. Thus a high CB1 receptor expression alone does not drive the cells towards a survival phenotype in the presence of a CB receptor agonist.

CONCLUSIONS

The data identify two potential regulators of the endocannabinoid system in prostate cancer and allow the construction of a model of a dysregulated endocannabinoid signaling network in this tumor. Further studies should be designed to test the veracity of the predictions of the network analysis in prostate cancer and other solid tumors.