Cannabidiol enhances the inhibitory effects of delta9-tetrahydrocannabinol on human glioblastoma cell proliferation and survival

Phytocannabinoids in neuromodulation: From omics to epigenetics

BACKGROUND

Recent developments in metabolomics, transcriptomic and epigenetics open up new horizons regarding the pharmacological understanding of phytocannabinoids as neuromodulators in treating anxiety, depression, epilepsy, Alzheimer's, Parkinson's disease and autism.

METHODS

The present review is an extensive search in public databases, such as Google Scholar, Scopus, the Web of Science, and PubMed, to collect all the literature about the neurobiological roles of cannabis extract, cannabidiol, 9-tetrahydrocannabinol specially focused on metabolomics, transcriptomic, epigenetic, mechanism of action, in different cell lines, induced animal models and clinical trials. We used bioinformatics, network pharmacology and enrichment analysis to understand the effect of phytocannabinoids in neuromodulation.

RESULTS

Cannabidomics studies show wide variability of metabolites across different strains and varieties, which determine their medicinal and abusive usage, which is very important for its quality control and regulation. CB receptors interact with other compounds besides cannabidiol and Δ9-tetrahydrocannabinol, like cannabinol and Δ8-tetrahydrocannabinol. Phytocannabinoids interact with cannabinoid and non-cannabinoid receptors (GPCR, ion channels, and PPAR) to improve various neurodegenerative diseases. However, its abuse because of THC is also a problem found across different epigenetic and transcriptomic studies. Network enrichment analysis shows CNR1 expression in the brain and its interacting genes involve different pathways such as Rap1 signalling, dopaminergic synapse, and relaxin signalling. CBD protects against diseases like epilepsy, depression, and Parkinson's by modifying DNA and mitochondrial DNA in the hippocampus. Network pharmacology analysis of 8 phytocannabinoids revealed an interaction with 10 (out of 60) targets related to neurodegenerative diseases, with enrichment of ErbB and PI3K-Akt signalling pathways which helps in ameliorating neuro-inflammation in various neurodegenerative diseases. The effects of phytocannabinoids vary across sex, disease state, and age which suggests the importance of a personalized medicine approach for better success.

CONCLUSIONS

Phytocannabinoids present a range of promising neuromodulatory effects. It holds promise if utilized in a strategic way towards personalized neuropsychiatric treatment. However, just like any drug irrational usage may lead to unforeseen negative effects. Exploring neuro-epigenetics and systems pharmacology of major and minor phytocannabinoid combinations can lead to success.

The antitumor action of endocannabinoids in the tumor microenvironment of glioblastoma

Approximately 80% of all malignant brain tumors are gliomas, which are primary brain tumors. The most prevalent subtype of glioma, glioblastoma multiforme (GBM), is also the most deadly. Chemotherapy, immunotherapy, surgery, and conventional pharmacotherapy are currently available therapeutic options for GBM; unfortunately, these approaches only prolong the patient's life by 5 years at most. Despite numerous intensive therapeutic options, GBM is considered incurable. Accumulating preclinical data indicate that overt antitumoral effects can be induced by pharmacologically activating endocannabinoid receptors on glioma cells by modifying important intracellular signaling cascades. The complex mechanism underlying the endocannabinoid receptor-evoked antitumoral activity in experimental models of glioma may inhibit the ability of cancer cells to invade, proliferate, and exhibit stem cell-like characteristics, along with altering other aspects of the complex tumor microenvironment. The exact biological function of the endocannabinoid system in the development and spread of gliomas, however, is remains unclear and appears to rely heavily on context. Previous studies have revealed that endocannabinoid receptors are present in the tumor microenvironment, suggesting that these receptors could be novel targets for the treatment of GBM. Additionally, endocannabinoids have demonstrated anticancer effects through signaling pathways linked to the classic features of cancer. Thus, the pharmacology of endocannabinoids in the glioblastoma microenvironment is the main topic of this review, which may promote the development of future GBM therapies.

Research Progress on the Mechanism of the Antitumor Effects of Cannabidiol

Cannabidiol (CBD), a non-psychoactive ingredient extracted from the hemp plant, has shown therapeutic effects in a variety of diseases, including anxiety, nervous system disorders, inflammation, and tumors. CBD can exert its antitumor effect by regulating the cell cycle, inducing tumor cell apoptosis and autophagy, and inhibiting tumor cell invasion, migration, and angiogenesis. This article reviews the proposed antitumor mechanisms of CBD, aiming to provide references for the clinical treatment of tumor diseases and the rational use of CBD.

Effects of Cannabidiol, ∆9-Tetrahydrocannabinol, and WIN 55-212-22 on the Viability of Canine and Human Non-Hodgkin Lymphoma Cell Lines

In our previous study, we demonstrated the impact of overexpression of CB1 and CB2 cannabinoid receptors and the inhibitory effect of endocannabinoids (2-arachidonoylglycerol (2-AG) and Anandamide (AEA)) on canine (Canis lupus familiaris) and human (Homo sapiens) non-Hodgkin lymphoma (NHL) cell lines' viability compared to cells treated with a vehicle. The purpose of this study was to demonstrate the anti-cancer effects of the phytocannabinoids, cannabidiol (CBD) and ∆9-tetrahydrocannabinol (THC), and the synthetic cannabinoid WIN 55-212-22 (WIN) in canine and human lymphoma cell lines and to compare their inhibitory effect to that of endocannabinoids. We used malignant canine B-cell lymphoma (BCL) (1771 and CLB-L1) and T-cell lymphoma (TCL) (CL-1) cell lines, and human BCL cell line (RAMOS). Our cell viability assay results demonstrated, compared to the controls, a biphasic effect (concentration range from 0.5 μM to 50 μM) with a significant reduction in cancer viability for both phytocannabinoids and the synthetic cannabinoid. However, the decrease in cell viability in the TCL CL-1 line was limited to CBD. The results of the biochemical analysis using the 1771 BCL cell line revealed a significant increase in markers of oxidative stress, inflammation, and apoptosis, and a decrease in markers of mitochondrial function in cells treated with the exogenous cannabinoids compared to the control. Based on the IC50 values, CBD was the most potent phytocannabinoid in reducing lymphoma cell viability in 1771, Ramos, and CL-1. Previously, we demonstrated the endocannabinoid AEA to be more potent than 2-AG. Our study suggests that future studies should use CBD and AEA for further cannabinoid testing as they might reduce tumor burden in malignant NHL of canines and humans.

Cannabinoids in the treatment of glioblastoma

Glioblastoma (GBM) is the most prevalent primary malignant tumor of the nervous system. While the treatment of other neoplasms is increasingly more efficacious the median survival rate of GBM patients remains low and equals about 14 months. Due to this fact, there are intensive efforts to find drugs that would help combat GBM. Nowadays cannabinoids are becoming more and more important in the field of cancer and not only because of their properties of antiemetic drugs during chemotherapy. These compounds may have a direct cytotoxic effect on cancer cells. Studies indicate GBM has disturbances in the endocannabinoid system-changes in cannabinoid metabolism as well as in the cannabinoid receptor expression. The GBM cells show expression of cannabinoid receptors 1 and 2 (CB1R and CB2R), which mediate various actions of cannabinoids. Through these receptors, cannabinoids inhibit the proliferation and invasion of GBM cells, along with changing their morphology. Cannabinoids also induce an intrinsic pathway of apoptosis in the tumor. Hence the use of cannabinoids in the treatment of GBM may be beneficial to the patients. So far, studies focusing on using cannabinoids in GBM therapy are mainly preclinical and involve cell lines and mice. The results are promising and show cannabinoids inhibit GBM growth. Several clinical studies are also being carried out. The preliminary results show good tolerance of cannabinoids and prolonged survival after administration of these drugs. In this review, we describe the impact of cannabinoids on GBM and glioma cells in vitro and in animal studies. We also provide overview of clinical trials on using cannabinoids in the treatment of GBM.

Anti-proliferative and apoptotic effect of cannabinoids on human pancreatic ductal adenocarcinoma xenograft in BALB/c nude mice model

Human pancreatic ductal adenocarcinoma (PDAC) is a highly malignant and lethal tumor of the exocrine pancreas. Cannabinoids extracted from the hemp plant Cannabis sativa have been suggested as a potential therapeutic agent in several human tumors. However, the anti-tumor effect of cannabinoids on human PDAC is not entirely clarified. In this study, the anti-proliferative and apoptotic effect of cannabinoid solution (THC:CBD at 1:6) at a dose of 1, 5, and 10 mg/kg body weight compared to the negative control (sesame oil) and positive control (5-fluorouracil) was investigated in human PDAC xenograft nude mice model. The findings showed that cannabinoids significantly decreased the mitotic cells and mitotic/apoptotic ratio, meanwhile dramatically increased the apoptotic cells. Parallelly, cannabinoids significantly downregulated Ki-67 and PCNA expression levels. Interestingly, cannabinoids upregulated BAX, BAX/BCL-2 ratio, and Caspase-3, meanwhile, downregulated BCL-2 expression level and could not change Caspase-8 expression level. These findings suggest that cannabinoid solution (THC:CBD at 1:6) could inhibit proliferation and induce apoptosis in human PDAC xenograft models. Cannabinoids, including THC:CBD, should be further studied for use as the potent PDCA therapeutic agent in humans.

Targeting Nrf2 Signaling Pathway in Cancer Prevention and Treatment: The Role of Cannabis Compounds

The development and progression of cancer are associated with the dysregulation of multiple pathways involved in cell proliferation and survival, as well as dysfunction in redox balance, immune response, and inflammation. The master antioxidant pathway, known as the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, regulates the cellular defense against oxidative stress and inflammation, making it a promising cancer prevention and treatment target. Cannabinoids have demonstrated anti-tumor and anti-inflammatory properties, affecting signaling pathways, including Nrf2. Increased oxidative stress following exposure to anti-cancer therapy prompts cancer cells to activate antioxidant mechanisms. This indicates the dual effect of Nrf2 in cancer cells-influencing proliferation and apoptotic processes and protecting against the toxicity of anti-cancer therapy. Therefore, understanding the complex role of cannabinoids in modulating Nrf2 might shed light on its potential implementation as an anti-cancer support. In this review, we aim to highlight the impact of cannabinoids on Nrf2-related factors, with a focus on cancer prevention and treatment. Additionally, we have presented the results of several research studies that combined cannabidiol (CBD) with other compounds targeting Nrf2. Further studies should be directed toward exploring the anti-inflammatory effects of cannabinoids in the context of cancer prevention and therapy.

The current role of cannabis and cannabinoids in health: A comprehensive review of their therapeutic potential

There has been an increased interest of the scientific community in cannabis and its constituents for therapeutic purposes. Although it is believed that cannabinoids can be effective for a few different conditions and syndromes, there are little objective data that clearly support the use of cannabis, cannabis extracts or even cannabidiol (CBD) oil. This review aims to explore the therapeutic potential of phytocannabinoids and synthetic cannabinoids for the treatment of several diseases. A broad search covering the past five years, was performed in PubMed and ClinicalTrial.gov databases, to identify papers focusing on the use of medical phytocannabinoids in terms of tolerability, efficacy and safety. Accordingly, there are preclinical data supporting the use of phytocannabinoids and synthetic cannabinoids for the management of neurological pathologies, acute and chronical pain, cancer, psychiatric disorders and chemotherapy-induced emetic symptoms. However, regarding the clinical trials, most of the collected data do not fully support the use of cannabinoids in the treatment of such conditions. Consequently, more studies are still needed to clarify ascertain if the use of these compounds is useful in the management of different pathologies.

Tetrahydrocannabinols: potential cannabimimetic agents for cancer therapy

Tetrahydrocannabinols (THCs) antagonize the CB1 and CB2 cannabinoid receptors, whose signaling to the endocannabinoid system is essential for controlling cell survival and proliferation as well as psychoactive effects. Most tumor cells express a much higher level of CB1 and CB2; THCs have been investigated as potential cancer therapeutic due to their cannabimimetic properties. To date, THCs have been prescribed as palliative medicine to cancer patients but not as an anticancer modality. Growing evidence of preclinical research demonstrates that THCs reduce tumor progression by stimulating apoptosis and autophagy and inhibiting two significant hallmarks of cancer pathogenesis: metastasis and angiogenesis. However, the degree of their anticancer effects depends on the origin of the tumor site, the expression of cannabinoid receptors on tumor cells, and the dosages and types of THC. This review summarizes the current state of knowledge on the molecular processes that THCs target for their anticancer effects. It also emphasizes the substantial knowledge gaps that should be of concern in future studies. We also discuss the therapeutic effects of THCs and the problems that will need to be addressed in the future. Clarifying unanswered queries is a prerequisite to translating the THCs into an effective anticancer regime.

Glioblastoma Biology, Genetics and Possible Therapies

Glioblastoma is the most aggressive intracranial tumor [...].

Should oncologists trust cannabinoids?

Cannabis enjoyed a "golden age" as a medicinal product in the late 19th, early 20th century, but the increased risk of overdose and abuse led to its criminalization. However, the 21st century have witnessed a resurgence of interest and a large body of literature regarding the benefits of cannabinoids have emerged. As legalization and decriminalization have spread around the world, cancer patients are increasingly interested in the potential utility of cannabinoids. Although eager to discuss cannabis use with their oncologist, patients often find them to be reluctant, mainly because clinicians are still not convinced by the existing evidence-based data to guide their treatment plans. Physicians should prescribe cannabis only if a careful explanation can be provided and follow up response evaluation ensured, making it mandatory for them to be up to date with the positive and also negative aspects of the cannabis in the case of cancer patients. Consequently, this article aims to bring some clarifications to clinicians regarding the sometimes-confusing various nomenclature under which this plant is mentioned, current legislation and the existing evidence (both preclinical and clinical) for the utility of cannabinoids in cancer patients, for either palliation of the associated symptoms or even the potential antitumor effects that cannabinoids may have.

Therapeutic targeting of the tumor microenvironments with cannabinoids and their analogs: Update on clinical trials

Cancer is a major global public health concern that affects both industrialized and developing nations. Current cancer chemotherapeutic options are limited by side effects, but plant-derived alternatives and their derivatives offer the possibilities of enhanced treatment response and reduced side effects. A plethora of recently published articles have focused on treatments based on cannabinoids and cannabinoid analogs and reported that they positively affect healthy cell growth and reverse cancer-related abnormalities by targeting aberrant tumor microenvironments (TMEs), lowering tumorigenesis, preventing metastasis, and/or boosting the effectiveness of chemotherapy and radiotherapy. Furthermore, TME modulating systems are receiving much interest in the cancer immunotherapy field because it has been shown that TMEs have significant impacts on tumor progression, angiogenesis, invasion, migration, epithelial to mesenchymal transition, metastasis and development of drug resistance. Here, we have reviewed the effective role of cannabinoids, their analogs and cannabinoid nano formulations on the cellular components of TME (endothelial cells, pericytes, fibroblast and immune cells) and how efficiently it retards the progression of carcinogenesis is discussed. The article summarizes the existing research on the molecular mechanisms of cannabinoids regulation of the TME and finally highlights the human studies on cannabinoids' active interventional clinical trials. The conclusion outlines the need for future research involving clinical trials of cannabinoids to demonstrate their efficacy and activity as a treatment/prevention for various types of human malignancies.

Cannabinoids as Potential Cancer Therapeutics: The Concentration Conundrum

Background: Studies have reported that cannabinoids, in particular Δ⁹-tetrahydrocannabinol (Δ⁹-THC) and cannabidiol (CBD), significantly reduce cancer cell viability in vitro. Unfortunately, treatment conditions vary significantly across reports. In particular, a majority of reports utilize conditions with reduced serum concentrations (0-3%) that may compromise the growth of the cells themselves, as well as the observed results. Objectives: This study was designed to test the hypothesis that, based on their known protein binding characteristics, cannabinoids would be less effective in the presence of fetal bovine serum (FBS). Moreover, we wished to determine if the treatments served to be cytotoxic or cytostatic under these conditions. Methods: Six cancer cell lines, representing two independent lines of three different types of cancer (glioblastoma, melanoma, and colorectal cancer [CRC]), were treated with 10 μM pure Δ⁹-THC, CBD, KM-233, and HU-331 for 48 h (in the presence or absence of FBS). Cell viability was measured with the MTT assay. Dose-response curves were then generated comparing the potencies of the four cannabinoids under the same conditions. Results: We found that serum-free medium alone produces cell cycle arrest for CRC cells and slows cell growth for the other cancer types. The antineoplastic effects of three of the four cannabinoids (Δ⁹-THC, CBD, and KM-233) increase when serum is omitted from the media. In addition, dose-response curves for these drugs demonstrated lower IC₅₀ values for serum-free media compared with the media with 10% serum in all cell lines. The fourth compound, HU-331, was equally effective under both conditions. A further confound we observed is that omission of serum produces dramatic binding of Δ⁹-THC and CBD to plastic. Conclusions: Treatment of cancer cells in the absence of FBS appears to enhance the potency of cannabinoids. However, omission of FBS itself compromises cell growth and represents a less physiological condition. Given the knowledge that cannabinoids are 90-95% protein bound and have well-known affinities for plastic, it may be ill-advised to treat cells under conditions where the cells are not growing optimally and where known concentrations cannot be assumed (i.e., FBS-free conditions).

A Comprehensive Review on Cannabis sativa Ethnobotany, Phytochemistry, Molecular Docking and Biological Activities

For more than a century, Cannabis was considered a narcotic and has been banned by lawmakers all over the world. In recent years, interest in this plant has increased due to its therapeutic potential, in addition to a very interesting chemical composition, characterized by the presence of an atypical family of molecules known as phytocannabinoids. With this emerging interest, it is very important to take stock of what research has been conducted so far on the chemistry and biology of Cannabis sativa. The aim of this review is to describe the traditional uses, chemical composition and biological activities of different parts of this plant, as well as the molecular docking studies. Information was collected from electronic databases, namely SciFinder, ScienceDirect, PubMed and Web of Science. Cannabis is mainly popular for its recreational use, but it is also traditionally used as remedy for the treatment of several diseases, including diabetes, digestive, circulatory, genital, nervous, urinary, skin and respiratory diseases. These biological proprieties are mainly due to the presence of bioactive metabolites represented by more than 550 different molecules. Molecular docking simulations proved the presence of affinities between Cannabis compounds and several enzymes responsible for anti-inflammatory, antidiabetic, antiepileptic and anticancer activities. Several biological activities have been evaluated on the metabolites of Cannabis sativa, and these works have shown the presence of antioxidant, antibacterial, anticoagulant, antifungal, anti-aflatoxigenic, insecticidal, anti-inflammatory, anticancer, neuroprotective and dermocosmetic activities. This paper presents the up-to-date reported investigations and opens many reflections and further research perspectives.

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.

Interactions between Natural Products-A Review

Plant-based natural products have been used as a source for therapeutics since the dawn of civilization. According to the World Health Organization (WHO), more than 80% of the world's population relies on traditional medicine for their primary healthcare. Numerous natural extracts, widely known in Traditional Chinese Medicine, Indian Ayurveda medicine and other practices, have led to the modern discovery and development of new drugs. Plants continuously interact with their environment, producing new compounds and ever-changing combinations of existing ones. Interestingly, some of the compounds have shown lower therapeutic activity in comparison to the extract they were isolated from. These findings suggest that the higher therapeutic activity of the source extract was due to the synergistic effect of several compounds. In other words, the total therapeutic potential of the extract cannot be explained only by the sum of its parts alone. In traditional medicine, most herbal remedies are based on a mixture of plants, and it is the interaction between different constituents that amplifies their therapeutic potential. Considering the significant influence traditional medicine has on human healthcare, knowing and studying the synergistic effect of compounds is paramount in designing smart therapeutic agents.

Cannabinoids as Immune System Modulators: Cannabidiol Potential Therapeutic Approaches and Limitations

Introduction: Cannabidiol (CBD) is the second most abundant Phytocannabinoid in Cannabis extracts. CBD has a binding affinity for several cannabinoid and cannabinoid-associated receptors. Epidiolex (oral CBD solution) has been lately licensed by the Food and Drug Administration (FDA) for the treatment of pediatric epileptic seizures. Methods: In this review, we discussed the most promising applications of CBD for chronic inflammatory conditions, namely CBD's anti-inflammatory effects during inflammatory bowel disease, coronavirus disease (antiviral effect), brain pathologies (neuroprotective and anti-inflammatory properties), as well as CBD immunomodulatory and antitumoral activities in the tumor microenvironment. Special focus was shed on the main therapeutic mechanisms of action of CBD, particularly in the control of the immune system and the endocannabinoid system. Results: Findings suggest that CBD is a potent immunomodulatory drug as it has manifested immunosuppressive properties in the context of sterile inflammation (e.g., inflammatory bowel disease, rheumatoid arthritis, and neurodegenerative diseases), and immunoprotective effects during viral infections (e.g. COVID-19) Similarly, CBD has exhibited a selective response toward cancer types by engaging different targets and signaling pathways. These results are in favor of the primary function of the endocannabinoid system which is homeostatic maintenance. Conclusion: The presented evidence suggests that the endocannabinoid system is a prominent target for the treatment of inflammatory and autoimmune diseases, rheumatoid diseases, viral infections, neurological and psychological pathologies, and cancer. Moreover, the antitumoral activities of CBD have been suggested to be potentially used in combination with chemo- or immunotherapy during cancer. However, clinical results are still lacking, which raises a challenge to apply translational cannabis research to the human immune system.

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.

Expression of cannabinoid receptors CB1 and CB2 in canine cutaneous mast cell tumours

Cannabinoid receptors (CB1 and CB2) belong to endocannabinoid system (ECS), which is also composed from endocannabinoids and the enzymatic systems involved in their biosynthesis and degradation. The expression of CB1 and CB2 have been previously identified in normal canine mast cell and in atopic dermatitis. Canine cutaneous mast cell tumours (cMCTs) are among the most common cutaneous neoplasms in dogs and have a highly variable clinical behaviour. Expression of CB1-CB2 was assessed by means of immunohistochemistry in thirty-seven dogs (from 2019 to 2021) with proven histological diagnosis of cMCT. Dogs were divided in two groups according to the Kiupel's grading system: high-grade (HG) cMCT and low-grade (LG) cMCT. A semiquantitative (score 0-3) and quantitative assessment of immunoreactivity (IR) was performed for each case. Our results show that there CB1 and CB2 are highly expressed in LG- cMCT, in contrast to HG- cMCT.

The Combination of Δ9-Tetrahydrocannabinol and Cannabidiol Suppresses Mitochondrial Respiration of Human Glioblastoma Cells via Downregulation of Specific Respiratory Chain Proteins

Simple Summary

Cannabidiol (CBD) is a phytocannabinoid from Cannabis sativa L. that exhibits no psychoactivity and, like the psychoactive cannabinoid Δ⁹-tetrahydrocannabinol (THC), shows anticancer effects in preclinical cell and animal models. Previous studies have indicated a stronger cancer-targeting effect when THC and CBD are combined. Here, we investigated how the combination of THC and CBD in a 1:1 ratio affects glioblastoma cell survival. The compounds were found to synergistically enhance cell death, which was attributed to mitochondrial damage and disruption of energy metabolism. A detailed look at the mitochondrial electron transfer chain showed that THC/CBD selectively decreased certain subunits of complexes I and IV. These data highlight the fundamental changes in cellular energy metabolism when cancer cells are exposed to a mixture of cannabinoids and underscore the potential of combining cannabinoids in cancer treatment.

Abstract

Phytocannabinoids represent a promising approach in glioblastoma therapy. Previous work has shown that a combined treatment of glioblastoma cells with submaximal effective concentrations of psychoactive Δ⁹-tetrahydrocannabinol (THC) and non-psychoactive cannabidiol (CBD) greatly increases cell death. In the present work, the glioblastoma cell lines U251MG and U138MG were used to investigate whether the combination of THC and CBD in a 1:1 ratio is associated with a disruption of cellular energy metabolism, and whether this is caused by affecting mitochondrial respiration. Here, the combined administration of THC and CBD (2.5 µM each) led to an inhibition of oxygen consumption rate and energy metabolism. These effects were accompanied by morphological changes to the mitochondria, a release of mitochondrial cytochrome c into the cytosol and a marked reduction in subunits of electron transport chain complexes I (NDUFA9, NDUFB8) and IV (COX2, COX4). Experiments with receptor antagonists and inhibitors showed that the degradation of NDUFA9 occurred independently of the activation of the cannabinoid receptors CB₁, CB₂ and TRPV1 and of usual degradation processes mediated via autophagy or the proteasomal system. In summary, the results describe a previously unknown mitochondria-targeting mechanism behind the toxic effect of THC and CBD on glioblastoma cells that should be considered in future cancer therapy, especially in combination strategies with other chemotherapeutics.

Anti-cancer activities of Schedule E1 drugs used in ayurvedic formulations

Schedule E1 is an important part of Drugs and Cosmetics Act (Government of India) that comprises the list of poisonous drugs from plant, animal and mineral origins to be consumed under medical supervision. Ayurveda, the world's oldest medicinal system has a list of drugs represented in schedule E1 that are used since thousands of years. This review reports the anti-cancer activities of fifteen toxic ayurvedic drugs from plant origin represented in Drugs and Cosmetics Act, 1940. The information was collected from the various authentic sources, compiled and summarised. The plant extracts, formulations, phytoconstituents and other preparations of these drugs have shown effective activities against mammary carcinoma, neuroblastoma, non-small cell lung carcinoma, lymphocytic leukaemia, colorectal adenocarcinoma, Ehrlich ascites carcinoma, prostate adenocarcinoma, glioblastoma asterocytoma and other malignancies. They have various mechanisms of action including Bax upregulation, Bcl₂ downregulation, induction of cell cycle arrest at S phase, G2/M phase, inhibition of vascular endothelial growth factors, inhibition of Akt/mTOR signalling etc. Certain traditional ayurvedic preparations containing these plants are reported beneficial and the possibilities of these drugs as the alternative and adjuvant therapeutic agents in the current cancer care have been discussed. The studies suggest that these drugs could be utilised in future for the critical care of malignancies.

Epidemiology of Glioblastoma Multiforme–Literature Review

Simple Summary

Glioblastoma multiforme (GBM) is one of the most aggressive malignancies, accounting for 14.5% of all central nervous system tumors and 48.6% of malignant central nervous system tumors. The median overall survival (OS) of GBM patients is only 15 months. The aim of this review was to provide an overview of the epidemiology of GBM and factors that may have a significant impact on the risk of GBM.

Abstract

Glioblastoma multiforme (GBM) is one of the most aggressive malignancies, with a median overall survival of approximately 15 months. In this review, we analyze the pathogenesis of GBM, as well as epidemiological data, by age, gender, and tumor location. The data indicate that GBM is the higher-grade primary brain tumor and is significantly more common in men. The risk of being diagnosed with glioma increases with age, and median survival remains low, despite medical advances. In addition, it is difficult to determine clearly how GBM is influenced by stimulants, certain medications (e.g., NSAIDs), cell phone use, and exposure to heavy metals.

Cannabis Biomolecule Effects on Cancer Cells and Cancer Stem Cells: Cytotoxic, Anti-Proliferative, and Anti-Migratory Activities

Cancer is a complex family of diseases affecting millions of people worldwide. Gliomas are primary brain tumors that account for ~80% of all malignant brain tumors. Glioblastoma multiforme (GBM) is the most common, invasive, and lethal subtype of glioma. Therapy resistance and intra-GBM tumoral heterogeneity are promoted by subpopulations of glioma stem cells (GSCs). Cannabis sativa produces hundreds of secondary metabolites, such as flavonoids, terpenes, and phytocannabinoids. Around 160 phytocannabinoids have been identified in C. sativa. Cannabis is commonly used to treat various medical conditions, and it is used in the palliative care of cancer patients. The anti-cancer properties of cannabis compounds include cytotoxic, anti-proliferative, and anti-migratory activities on cancer cells and cancer stem cells. The endocannabinoids system is widely distributed in the body, and its dysregulation is associated with different diseases, including various types of cancer. Anti-cancer activities of phytocannabinoids are mediated in glioma cells, at least partially, by the endocannabinoid receptors, triggering various cellular signaling pathways, including the endoplasmic reticulum (ER) stress pathway. Specific combinations of multiple phytocannabinoids act synergistically against cancer cells and may trigger different anti-cancer signaling pathways. Yet, due to scarcity of clinical trials, there remains no solid basis for the anti-cancer therapeutic potential of cannabis compounds.

Cannabidiol on the Path from the Lab to the Cancer Patient: Opportunities and Challenges

Cannabidiol (CBD), a major non-psychotropic component of cannabis, is receiving growing attention as a potential anticancer agent. CBD suppresses the development of cancer in both in vitro (cancer cell culture) and in vivo (xenografts in immunodeficient mice) models. For critical evaluation of the advances of CBD on its path from laboratory research to practical application, in this review, we wish to call the attention of scientists and clinicians to the following issues: (a) the biological effects of CBD in cancer and healthy cells; (b) the anticancer effects of CBD in animal models and clinical case reports; (c) CBD’s interaction with conventional anticancer drugs; (d) CBD’s potential in palliative care for cancer patients; (e) CBD’s tolerability and reported side effects; (f) CBD delivery for anticancer treatment.

Chronic Administration of Cannabinoid Receptor 2 Agonist (JWH-133) Increases Ectopic Ovarian Tumor Growth and Endocannabinoids (Anandamide and 2-Arachidonoyl Glycerol) Levels in Immunocompromised SCID Female Mice

Cannabinoid-based therapies are increasingly being used by cancer patients to treat chemotherapy-induced nausea and vomiting. Recently, cannabinoids have gained increased attention for their effects on cancer growth. Indeed, the effect of CB₂ (JWH-015, JWH-133) agonists on breast cancer models have shown to reduce the size of breast cancer tumors. However, these studies assessing breast cancer progression were using CB₂ agonist administered early into the cancer progression therefore assessing their effects on already established tumors is a critical need. In our study, we evaluate tumor growth using an ectopic xenograft ovarian (SKOV-3 and OVCAR-5) cancer model. The impact of chronic (30 days) administration of CB₂ (JWH-133) agonist will be evaluated and started on 30 days of ectopic ovarian tumors. We will then evaluate and determine the mechanisms involved in ovarian cancer tumor growth by measuring levels of anandamide and 2-arachidonoyl glycerol as well as protein levels of CB₁, CB₂, ERα, ERβ, GPER, TNFα, IL-1β and IL-6 in ovarian and tumor tissues. Our results demonstrate a significant increase in ectopic ovarian tumor growth following chronic administration of JWH-133. Ovarian cancer tumor tissues chronically (30 days) treated with JWH-133 in comparison to vehicle treated groups showed an increase in endocannabinoid (AEA and 2-AG) and protein (CB₂ and TNFα) levels with a decrease in GPER protein levels. Interestingly, our study emphasizes the importance of studying the impact of cannabinoid compounds on already established tumors to improve our understanding of cannabinoid-based therapies and, therefore better address clinical needs in cancer patients.

Cannabidiol and Other Phytocannabinoids as Cancer Therapeutics

Preclinical models provided ample evidence that cannabinoids are cytotoxic against cancer cells. Among the best studied phytocannabinoids, cannabidiol (CBD) is most promising for the treatment of cancer as it lacks the psychotomimetic properties of delta-9-tetrahydrocannabinol (THC). In vitro studies and animal experiments point to a concentration- (dose-)dependent anticancer effect. The effectiveness of pure compounds versus extracts is the subject of an ongoing debate. Actual results demonstrate that CBD-rich hemp extracts must be distinguished from THC-rich cannabis preparations. Whereas pure CBD was superior to CBD-rich extracts in most in vitro experiments, the opposite was observed for pure THC and THC-rich extracts, although exceptions were noted. The cytotoxic effects of CBD, THC and extracts seem to depend not only on the nature of cannabinoids and the presence of other phytochemicals but also largely on the nature of cell lines and test conditions. Neither CBD nor THC are universally efficacious in reducing cancer cell viability. The combination of pure cannabinoids may have advantages over single agents, although the optimal ratio seems to depend on the nature of cancer cells; the existence of a 'one size fits all' ratio is very unlikely. As cannabinoids interfere with the endocannabinoid system (ECS), a better understanding of the circadian rhythmicity of the ECS, particularly endocannabinoids and receptors, as well as of the rhythmicity of biological processes related to the growth of cancer cells, could enhance the efficacy of a therapy with cannabinoids by optimization of the timing of the administration, as has already been reported for some of the canonical chemotherapeutics. Theoretically, a CBD dose administered at noon could increase the peak of anandamide and therefore the effects triggered by this agent. Despite the abundance of preclinical articles published over the last 2 decades, well-designed controlled clinical trials on CBD in cancer are still missing. The number of observations in cancer patients, paired with the anticancer activity repeatedly reported in preclinical in vitro and in vivo studies warrants serious scientific exploration moving forward.

Small Molecule Compounds of Natural Origin Target Cellular Receptors to Inhibit Cancer Development and Progression

Receptors are macromolecules that transmit information regulating cell proliferation, differentiation, migration and apoptosis, play key roles in oncogenic processes and correlate with the prognoses of cancer patients. Thus, targeting receptors to constrain cancer development and progression has gained widespread interest. Small molecule compounds of natural origin have been widely used as drugs or adjuvant chemotherapeutic agents in cancer therapies due to their activities of selectively killing cancer cells, alleviating drug resistance and mitigating side effects. Meanwhile, many natural compounds, including those targeting receptors, are still under laboratory investigation for their anti-cancer activities and mechanisms. In this review, we classify the receptors by their structures and functions, illustrate the natural compounds targeting these receptors and discuss the mechanisms of their anti-cancer activities. We aim to provide primary knowledge of mechanistic regulation and clinical applications of cancer therapies through targeting deregulated receptors.

Cannabidiol Inhibits RAD51 and Sensitizes Glioblastoma to Temozolomide in Multiple Orthotopic Tumor Models

Background

Cannabidiol (CBD), a nonpsychoactive cannabinoid with a low toxicity profile, has been shown to produce antitumor activity across cancers in part through selective production of reactive oxygen species (ROS) in tumor cells. The alkylating agent, temozolomide (TMZ), is standard of care for treatment of glioblastoma (GBM). It can trigger increased ROS to induce DNA damage. It has also been reported that downregulating the expression of RAD51, an important DNA damage repair protein, leads to sensitization of GBM to TMZ.

Methods

We determined the extent to which CBD enhanced the antitumor activity of TMZ in multiple orthotopic models of GBM. In addition, we investigated the potential for CBD to enhance the antitumor activity of TMZ through production of ROS and modulation of DNA repair pathways.

Results

CBD enhanced the activity of TMZ in U87 MG and U251 GBM cell lines and in patient-derived primary GBM163 cells leading to stimulation of ROS, activation of the ROS sensor AMP-activated protein kinase (AMPK), and upregulation of the autophagy marker LC3A. CBD produced a sensitization of U87 and GBM163-derived intracranial (i.c.) tumors to TMZ and significantly increased survival of tumor-bearing mice. However, these effects were not observed in orthotopic models derived from GBM with intact methylguanine methyltransferase (MGMT) expression. We further demonstrate that CBD inhibited RAD51 expression in MGMT-methylated models of GBM, providing a potential mechanism for tumor sensitization to TMZ by CBD.

Conclusion

These data support the potential therapeutic benefits of using CBD to enhance the antitumor activity of TMZ in GBM patients.

Bee Venom Effect on Glioblastoma Cells Viability and Gelatinase Secretion

Background

The involvement of MMP-2 and MMP-9 in the pathogenesis of various kinds of cancers including glioblastoma is well documented. The evaluation of the anticancer potential of honey bee (Apis mellifera) venom (BV) consisting of the inhibition of MMP-2 and MMP-9 secretion in a glioblastoma cell culture model was the aim of the study.

Methods

8-MG-BA and GAMG human primary glioblastoma cell lines vs. HT-22 mouse hippocampal neuronal cells were applied for the study. The BV dose (0.5, 1.0, 1.25, 1.5, 1.75, 2.0, 2.5, and 5.0 μg/ml) and time-dependent (24, 48, 72 h) cytotoxicity was evaluated with the tetrazolium-based colorimetric assay (MTT test). MMP-2 and MMP-9 activities in the cell culture medium under different BV concentrations were determined by gelatin zymography.

Results

A dose and time-dependent BV effect on cytotoxicity of both glioblastoma cell lines and hippocampus line was observed. The weakest, but statistically important effect was exerted by BV on HT-22 cells. The greatest cytotoxic effect of BV was observed on the 8-MG-BA line, where a statistically significant reduction in viability was observed at the lowest BV dose and the shortest incubation time. The reduction of both gelatinases secretion was observed at 8-MG-BA and GAMG lines without significant effect of HT-22 cell line.

Conclusion

In vitro studies indicate that BV has both cytotoxic and inhibitory effects on the secretion of MMP-2 and MMP-9 in selected lines of glioma, suggesting anticancer properties of BV.

Applications of Cannabis Sativa L. in Food and Its Therapeutic Potential: From a Prohibited Drug to a Nutritional Supplement

Hemp (Cannabis sativa L.) is a herbaceous anemophilous plant that belongs to the Cannabinaceae family. The cannabis seed (hemp) has long been utilized as a food source and is commercially important as an edible oil source. In this review, the positive and negative health effects of cannabis, the relationship between cannabis and various diseases, and the use of cannabis in various food products have been discussed. In addition, the scientific literature on the potential use of cannabis and its derivatives as a dietary supplement for the prevention and treatment of inflammatory and chronic degenerative diseases in animals and humans has been reviewed. Cannabis is being developed as a key ingredient in a variety of food items, including bakery, confectionery, beverages, dairy, fruits, vegetables, and meat. Hemp seeds are high in readily digestible proteins, lipids, polyunsaturated fatty acids (PUFA), insoluble fiber, carbs, and favorable omega-6 PUFA acid to omega-3 PUFA ratio and have high nutritional value. The antioxidants of cannabis, such as polyphenols, help with anxiety, oxidative stress, and the risk of chronic illnesses, including cancer, neurological disorders, digestive problems, and skin diseases. Cannabis has been shown to have negative health impacts on the respiratory system, driving, and psychomotor functions, and the reproductive system. Overall, the purpose of this research is to stimulate more in-depth research on cannabis's adaptation in various foods and for the treatment of chronic illnesses.

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.

Cannabis and the Cancer Patient

Session 2 of the National Cancer Institute's Cannabis, Cannabinoids, and Cancer Research Workshop opened with testimony from a lymphoma survivor who detailed medicinal cannabis-related improvements in nausea, low appetite, insomnia, and mental health and the limited clinical counsel she received regarding cannabis use. Discussion next turned to the evolution of the legal landscape of cannabis in the United States, one in which state and federal laws frequently conflict and the Controlled Substance Act renders cannabis Schedule I. This legal climate creates conundrums for US medicinal cannabis researchers who contend with limited funding opportunities, avenues to source trial drug, and procedural red tape and for oncology clinicians who recommend medicinal cannabis to patients with some frequency while perceiving themselves as ill equipped to make such clinical recommendations. Ultimately, it creates challenges for cancer patients who find themselves turning to nonmedical and anecdotal information sources. The risks of cannabis use by the cancer patient were discussed next. These include infection, pharmacodynamic and pharmacokinetic drug-botanical interactions, cyclic nausea and vomiting, e-cigarette or vaping product use-associated illness, legal issues, and high cost. The session concluded with a broad survey of the research supporting oncologic cannabinoid use, conclusive evidence for chemotherapy-induced nausea and vomiting, and suggestive evidence for cancer-related pain.

Cannabidiol Induces Cell Death in Human Lung Cancer Cells and Cancer Stem Cells

Currently, there is no effective therapy against lung cancer due to the development of resistance. Resistance contributes to disease progression, recurrence, and mortality. The presence of so-called cancer stem cells could explain the ineffectiveness of conventional treatment, and the development of successful cancer treatment depends on the targeting also of cancer stem cells. Cannabidiol (CBD) is a cannabinoid with anti-tumor properties. However, the effects on cancer stem cells are not well understood. The effects of CBD were evaluated in spheres enriched in lung cancer stem cells and adherent lung cancer cells. We found that CBD decreased viability and induced cell death in both cell populations. Furthermore, we found that CBD activated the effector caspases 3/7, increased the expression of pro-apoptotic proteins, increased the levels of reactive oxygen species, as well as a leading to a loss of mitochondrial membrane potential in both populations. We also found that CBD decreased self-renewal, a hallmark of cancer stem cells. Overall, our results suggest that CBD is effective against the otherwise treatment-resistant cancer stem cells and joins a growing list of compounds effective against cancer stem cells. The effects and mechanisms of CBD in cancer stem cells should be further explored to find their Achilles heel.

The strengths and limits of cannabinoids and their receptors in cancer: Insights into the role of tumorigenesis-underlying mechanisms and therapeutic aspects

Cancer, as a mysterious and complex disease, has a multi-stage molecular process that uses the cellular molecular machine and multiple signaling pathways to its advantage. Cannabinoids, as terpenophenolic compounds and their derivatives, showed influences on immune system responses, inflammation, and cell growth that have sparked a growing interest in exploring their effects on cancer cell fate, as well. A large body of evidence in experimental models indicating the involvement of cannabinoids and their related receptors in cancer cell growth, development, and fate. In accordance, the present study provided insights regarding the strengths and limits of cannabinoids and their receptors in critical steps of tumorigenesis and its underlying molecular pathways such as; cancer cell proliferation, type of cell death pathway, angiogenesis, invasion, metastasis and, immune system response. Based on the results of the present study and due to the contribution of cannabinoids in various cancer cell growth control processes, these compounds cancer can be considered worthwhile in finding new alternatives for cancer therapy.

The Current and Potential Application of Medicinal Cannabis Products in Dentistry

Oral and dental diseases are a major global burden, the most common non-communicable diseases (NCDs), and may even affect an individual's general quality of life and health. The most prevalent dental and oral health conditions are tooth decay (otherwise referred to as dental caries/cavities), oral cancers, gingivitis, periodontitis, periodontal (gum) disease, Noma, oro-dental trauma, oral manifestations of HIV, sensitive teeth, cracked teeth, broken teeth, and congenital anomalies such as cleft lip and palate. Herbs have been utilized for hundreds of years in traditional Chinese, African and Indian medicine and even in some Western countries, for the treatment of oral and dental conditions including but not limited to dental caries, gingivitis and toothaches, dental pulpitis, halitosis (bad breath), mucositis, sore throat, oral wound infections, and periodontal abscesses. Herbs have also been used as plaque removers (chew sticks), antimicrobials, analgesics, anti-inflammatory agents, and antiseptics. Cannabis sativa L. in particular has been utilized in traditional Asian medicine for tooth-pain management, prevention of dental caries and reduction in gum inflammation. The distribution of cannabinoid (CB) receptors in the mouth suggest that the endocannabinoid system may be a target for the treatment of oral and dental diseases. Most recently, interest has been geared toward the use of Cannabidiol (CBD), one of several secondary metabolites produced by C. sativa L. CBD is a known anti-inflammatory, analgesic, anxiolytic, anti-microbial and anti-cancer agent, and as a result, may have therapeutic potential against conditions such burning mouth syndrome, dental anxiety, gingivitis, and possible oral cancer. Other major secondary metabolites of C. sativa L. such as terpenes and flavonoids also share anti-inflammatory, analgesic, anxiolytic and anti-microbial properties and may also have dental and oral applications. This review will investigate the potential of secondary metabolites of C. sativa L. in the treatment of dental and oral diseases.

Cannabinoids in the landscape of cancer

INTRODUCTION

Cannabinoids are a group of terpenophenolic compounds derived from the Cannabis sativa L. plant. There is a growing body of evidence from cell culture and animal studies in support of cannabinoids possessing anticancer properties.

METHOD

A database search of peer reviewed articles published in English as full texts between January 1970 and April 2021 in Google Scholar, MEDLINE, PubMed and Web of Science was undertaken. References of relevant literature were searched to identify additional studies to construct a narrative literature review of oncological effects of cannabinoids in pre-clinical and clinical studies in various cancer types.

RESULTS

Phyto-, endogenous and synthetic cannabinoids demonstrated antitumour effects both in vitro and in vivo. However, these effects are dependent on cancer type, the concentration and preparation of the cannabinoid and the abundance of receptor targets. The mechanism of action of synthetic cannabinoids, (-)-trans-Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD) has mainly been described via the traditional cannabinoid receptors; CB1 and CB2, but reports have also indicated evidence of activity through GPR55, TRPM8 and other ion channels including TRPA1, TRPV1 and TRPV2.

CONCLUSION

Cannabinoids have shown to be efficacious both as a single agent and in combination with antineoplastic drugs. These effects have occurred through various receptors and ligands and modulation of signalling pathways involved in hallmarks of cancer pathology. There is a need for further studies to characterise its mode of action at the molecular level and to delineate efficacious dosage and route of administration in addition to synergistic regimes.

The Endocannabinoid System: A Potential Target for the Treatment of Various Diseases

The Endocannabinoid System (ECS) is primarily responsible for maintaining homeostasis, a balance in internal environment (temperature, mood, and immune system) and energy input and output in living, biological systems. In addition to regulating physiological processes, the ECS directly influences anxiety, feeding behaviour/appetite, emotional behaviour, depression, nervous functions, neurogenesis, neuroprotection, reward, cognition, learning, memory, pain sensation, fertility, pregnancy, and pre-and post-natal development. The ECS is also involved in several pathophysiological diseases such as cancer, cardiovascular diseases, and neurodegenerative diseases. In recent years, genetic and pharmacological manipulation of the ECS has gained significant interest in medicine, research, and drug discovery and development. The distribution of the components of the ECS system throughout the body, and the physiological/pathophysiological role of the ECS-signalling pathways in many diseases, all offer promising opportunities for the development of novel cannabinergic, cannabimimetic, and cannabinoid-based therapeutic drugs that genetically or pharmacologically modulate the ECS via inhibition of metabolic pathways and/or agonism or antagonism of the receptors of the ECS. This modulation results in the differential expression/activity of the components of the ECS that may be beneficial in the treatment of a number of diseases. This manuscript in-depth review will investigate the potential of the ECS in the treatment of various diseases, and to put forth the suggestion that many of these secondary metabolites of Cannabis sativa L. (hereafter referred to as "C. sativa L." or "medical cannabis"), may also have potential as lead compounds in the development of cannabinoid-based pharmaceuticals for a variety of diseases.

Transient Receptor Potential (TRP) Ion Channels Involved in Malignant Glioma Cell Death and Therapeutic Perspectives

Among the most biologically, thus clinically, aggressive primary brain tumors are found malignant gliomas. Despite recent advances in adjuvant therapies, which include targeted and immunotherapies, after surgery and radio/chemotherapy, the tumor is recurrent and always lethal. Malignant gliomas also contain a pool of initiating stem cells that are highly invasive and resistant to conventional treatment. Ion channels and transporters are markedly involved in cancer cell biology, including glioma cell biology. Transient receptor potential (TRP) ion channels are calcium-permeable channels implicated in Ca²⁺ changes in multiple cellular compartments by modulating the driving force for Ca²⁺ entry. Recent scientific reports have shown that these channels contribute to the increase in glioblastoma aggressiveness, with glioblastoma representing the ultimate level of glioma malignancy. The current review focuses on each type of TRP ion channel potentially involved in malignant glioma cell death, with the ultimate goal of identifying new therapeutic targets to clinically combat malignant gliomas. It thus appears that cannabidiol targeting the TRPV2 type could be such a potential target.

Efficacy of cannabinoids against glioblastoma multiforme: A systematic review

INTRODUCTION

The increased incidence of Glioblastoma Multiforme, the most aggressive and most common primary brain tumour, is evident worldwide. Survival rates are reaching only 15 months due to its high recurrence and resistance to current combination therapies including oncotomy, radiotherapy and chemotherapy. Light has been shed in the recent years on the anticancer properties of cannabinoids from Cannabis sativa.

OBJECTIVE

To determine whether cannabinoids alone or in combination with radiotherapy and/or chemotherapy inhibit tumour progression, induce cancer cell death, inhibit metastasis and invasiveness and the mechanisms that underlie these actions.

METHOD

PubMed and Web of Science were used for a systemic search to find studies on the anticancer effects of natural cannabinoids on glioma cancer cells in vitro and/or in vivo.

RESULTS

A total of 302 papers were identified, of which 14 studies were found to fit the inclusion criteria. 5 studies were conducted in vitro, 2 in vivo and 7 were both in vivo and in vitro. 3 studies examined the efficacy of CBD, THC and TMZ, 1 study examined CBD and radiation, 2 studies examined efficacy of THC only and 3 studies examined the efficacy of CBD only. 1 study examined the efficacy of CBD, THC and radiotherapy, 2 studies examined the combination of CBD and THC and 2 more studies examined the efficacy of CBD and TMZ.

CONCLUSION

The evidence in this systematic review leads to the conclusion that cannabinoids possess anticancer potencies against glioma cells, however this effect varies with the combinations and dosages used. Studies so far were conducted on cells in culture and on mice as well as a small number of studies that were conducted on humans. Hence in order to have more accurate results, higher quality studies mainly including human clinical trials with larger sample sizes are necessitated urgently for GBM treatment.

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.

Cancer Initiation, Progression and Resistance: Are Phytocannabinoids from Cannabis sativa L. Promising Compounds?

Cannabis sativa L. is a source of over 150 active compounds known as phytocannabinoids that are receiving renewed interest due to their diverse pharmacologic activities. Indeed, phytocannabinoids mimic the endogenous bioactive endocannabinoids effects through activation of CB1 and CB2 receptors widely described in the central nervous system and peripheral tissues. All phytocannabinoids have been studied for their protective actions towards different biological mechanisms, including inflammation, immune response, oxidative stress that, altogether, result in an inhibitory activity against the carcinogenesis. The role of the endocannabinoid system is not yet completely clear in cancer, but several studies indicate that cannabinoid receptors and endogenous ligands are overexpressed in different tumor tissues. Recently, in vitro and in vivo evidence support the effectiveness of phytocannabinoids against various cancer types, in terms of proliferation, metastasis, and angiogenesis, actions partially due to their ability to regulate signaling pathways critical for cell growth and survival. The aim of this review was to report the current knowledge about the action of phytocannabinoids from Cannabis sativa L. against cancer initiation and progression with a specific regard to brain, breast, colorectal, and lung cancer as well as their possible use in the therapies. We will also report the known molecular mechanisms responsible for such positive effects. Finally, we will describe the actual therapeutic options for Cannabis sativa L. and the ongoing clinical trials.

Repurposing Cannabidiol as a Potential Drug Candidate for Anti-Tumor Therapies

In recent years, evidence has accumulated that cannabinoids-especially the non-psychoactive compound, cannabidiol (CBD)-possess promising medical and pharmacological activities that might qualify them as potential anti-tumor drugs. This review is based on multiple studies summarizing different mechanisms for how CBD can target tumor cells including cannabinoid receptors or other constituents of the endocannabinoid system, and their complex activation of biological systems that results in the inhibition of tumor growth. CBD also participates in anti-inflammatory activities which are related to tumor progression, as demonstrated in preclinical models. Although the numbers of clinical trials and tested tumor entities are limited, there is clear evidence that CBD has anti-tumor efficacy and is well tolerated in human cancer patients. In summary, it appears that CBD has potential as a neoadjuvant and/or adjuvant drug in therapy for cancer.

Specific Compositions of Cannabis sativa Compounds Have Cytotoxic Activity and Inhibit Motility and Colony Formation of Human Glioblastoma Cells In Vitro

Glioblastoma multiforme (GBM) is the most lethal subtype of glioma. Cannabis sativa is used for the treatment of various medical conditions. Around 150 phytocannabinoids have been identified in C. sativa, among them Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) that trigger GBM cell death. However, the optimal combinations of cannabis molecules for anti-GBM activity are unknown. Chemical composition was determined using high-performance liquid chromatography (HPLC) and gas chromatography mass spectrometry (GC/MS). Cytotoxic activity was determined by XTT and lactate dehydrogenase (LDH) assays and apoptosis and cell cycle by fluorescence-activated cell sorting (FACS). F-actin structures were observed by confocal microscopy, gene expression by quantitative PCR, and cell migration and invasion by scratch and transwell assays, respectively. Fractions of a high-THC cannabis strain extract had significant cytotoxic activity against GBM cell lines and glioma stem cells derived from tumor specimens. A standard mix (SM) of the active fractions F4 and F5 induced apoptosis and expression of endoplasmic reticulum (ER)-stress associated-genes. F4 and F5 inhibited cell migration and invasion, altered cell cytoskeletons, and inhibited colony formation in 2 and 3-dimensional models. Combinations of cannabis compounds exert cytotoxic, anti-proliferative, and anti-migratory effects and should be examined for efficacy on GBM in pre-clinical studies and clinical trials.

Functional Fine-Tuning of Metabolic Pathways by the Endocannabinoid System-Implications for Health and Disease

The endocannabinoid system (ECS) employs a huge network of molecules (receptors, ligands, and enzymatic machinery molecules) whose interactions with other cellular networks have still not been fully elucidated. Endogenous cannabinoids are molecules with the primary function of control of multiple metabolic pathways. Maintenance of tissue and cellular homeostasis by functional fine-tuning of essential metabolic pathways is one of the key characteristics of the ECS. It is implicated in a variety of physiological and pathological states and an attractive pharmacological target yet to reach its full potential. This review will focus on the involvement of ECS in glucose and lipid metabolism, food intake regulation, immune homeostasis, respiratory health, inflammation, cancer and other physiological and pathological states will be substantiated using freely available data from open-access databases, experimental data and literature review. Future directions should envision capturing its diversity and exploiting pharmacological options beyond the classical ECS suspects (exogenous cannabinoids and cannabinoid receptor monomers) as signaling through cannabinoid receptor heteromers offers new possibilities for different biochemical outcomes in the cell.

THC Reduces Ki67-Immunoreactive Cells Derived from Human Primary Glioblastoma in a GPR55-Dependent Manner

Glioblastoma (GBM) is the most frequent malignant tumor of the central nervous system in humans with a median survival time of less than 15 months. ∆⁹-Tetrahydrocannabinol (THC) and cannabidiol (CBD) are the best-characterized components of Cannabis sativa plants with modulating effects on cannabinoid receptors 1 and 2 (CB₁ and CB₂) and on orphan receptors such as GPR18 or GPR55. Previous studies have demonstrated anti-tumorigenic effects of THC and CBD in several tumor entities including GBM, mostly mediated via CB₁ or CB₂. In this study, we investigated the non-CB₁/CB₂ effects of THC on the cell cycle of GBM cells isolated from human tumor samples. Cell cycle entry was measured after 24 h upon exposure by immunocytochemical analysis of Ki67 as proliferation marker. The Ki67-reducing effect of THC was abolished in the presence of CBD, whereas CBD alone did not cause any changes. To identify the responsible receptor for THC effects, we first characterized the cells regarding their expression of different cannabinoid receptors: CB₁, CB₂, GPR18, and GPR55. Secondly, the receptors were pharmacologically blocked by application of their selective antagonists AM281, AM630, O-1918, and CID16020046 (CID), respectively. All examined cells expressed the receptors, but only in presence of the GPR55 antagonist CID was the THC effect diminished. Stimulation with the GPR55 agonist lysophosphatidylinositol (LPI) revealed similar effects as obtained for THC. The LPI effects were also inhibited by CBD and CID, confirming a participation of GPR55 and suggesting its involvement in modifying the cell cycle of patient-derived GBM cells.

Assessment of Cannabidiol and Δ9-Tetrahydrocannabiol in Mouse Models of Medulloblastoma and Ependymoma

Simple Summary

Phytocannabinoids Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) have been demonstrated to exhibit anti-cancer activity in preclinical models of brain cancer leading to new clinical trials for adults with glioblastoma. We describe here the first report that has investigated a role for THC and CBD in pediatric brain cancer. Cannabinoids had cytotoxic activity against medulloblastoma and ependymoma cells in vitro, functioning in part through the inhibition of cell cycle progression and the induction of autophagy. Despite these effects in vitro, when tested in orthotopic mouse models of medulloblastoma or ependymoma, no impact on animal survival was observed. Furthermore, cannabinoids neither enhanced nor impaired conventional chemotherapy in a medulloblastoma mouse model. These data show that while THC and CBD do have some effects on medulloblastoma and ependymoma cells, are well tolerated, and have minimal adverse effects, they do not appear to elicit any survival benefit in preclinical models of pediatric brain cancer.

Abstract

Children with medulloblastoma and ependymoma are treated with a multidisciplinary approach that incorporates surgery, radiotherapy, and chemotherapy; however, overall survival rates for patients with high-risk disease remain unsatisfactory. Data indicate that plant-derived cannabinoids are effective against adult glioblastoma; however, preclinical evidence supporting their use in pediatric brain cancers is lacking. Here we investigated the potential role for Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in medulloblastoma and ependymoma. Dose-dependent cytotoxicity of medulloblastoma and ependymoma cells was induced by THC and CBD in vitro, and a synergistic reduction in viability was observed when both drugs were combined. Mechanistically, cannabinoids induced cell cycle arrest, in part by the production of reactive oxygen species, autophagy, and apoptosis; however, this did not translate to increased survival in orthotopic transplant models despite being well tolerated. We also tested the combination of cannabinoids with the medulloblastoma drug cyclophosphamide, and despite some in vitro synergism, no survival advantage was observed in vivo. Consequently, clinical benefit from the use of cannabinoids in the treatment of high-grade medulloblastoma and ependymoma is expected to be limited. This study emphasizes the importance of preclinical models in validating therapeutic agent efficacy prior to clinical trials, ensuring that enrolled patients are afforded the most promising therapies available.

The effect of cannabidiol on canine neoplastic cell proliferation and mitogen-activated protein kinase activation during autophagy and apoptosis

Low tetrahydrocannabinol Cannabis sativa products, also known as hemp products, have become widely available and their use in veterinary patients has become increasingly popular. Despite prevalence of use, the veterinary literature is lacking and evidence-based resource for cannabinoid efficacy. The most prevailing cannabinoid found in hemp is cannabidiolic acid (CBDA) and becomes cannabidiol (CBD) during heat extraction; CBD has been studied for its direct anti-neoplastic properties alone and in combination with standard cancer therapies, yielding encouraging results. The objectives of our study were to explore the anti-proliferative and cell death response associated with in vitro treatment of canine cancer cell lines with CBD alone and combination with common chemotherapeutics, as well as investigation into major proliferative pathways (eg, p38, JNK, AKT and mTOR) potentially involved in the response to treatment with CBD. CBD significantly reduced canine cancer cell proliferation far better than CBDA across five canine neoplastic cell lines when treated with concentrations ranging from 2.5 to 10 μg/mL. Combinatory treatment with CBD and vincristine reduced cell proliferation in a synergistic or additive manner at anti-proliferative concentrations with less clear results using doxorubicin in combination with CBD. The cellular signalling effects of CBD treatment, showed that autophagy supervened induction of apoptosis and may be related to prompt induction of ERK and JNK phosphorylation prior to autophagy. In conclusion, CBD is effective at hindering cell proliferation and induction of autophagy and apoptosis rapidly across neoplastic cell lines and further clinical trials are needed to understand its efficacy and interactions with traditional chemotherapy.

Therapeutic potential of cannabinoids in combination cancer therapy

Derivatives of the plant Cannabis sativa have been used for centuries for both medical and recreational purposes, as well as industrial. The first proof of its medicinal use comes from ancient China, although there is evidence of its earlier utilization in Europe and Asia. In the 19th century, European practitioners started to employ cannabis extracts to treat tetanus, convulsions, and mental diseases and, in 1851, cannabis made its appearance in the Pharmacopoeia of the United States as an analgesic, hypnotic and anticonvulsant. It was only in 1937 that the Marijuana Tax Act prohibited the use of this drug in the USA. The general term Cannabis is commonly used by the scientific and scholar community to indicate derivatives of the plant Cannabis sativa. The word cannabinoid is a term describing chemical compounds that are either derivate of Cannabis (phytocannabinoids) or artificial analogues (synthetic) or are produced endogenously by the body (endocannabinoids). A more casual term "marijuana" or "weed", a compound derived from dried Cannabis flower tops and leaves, has progressively superseded the term cannabis when referred to its recreational use. The 2018 World health organisation (WHO) data suggest that nearly 2.5% of the global population (147 million) uses marijuana and some countries, such as Canada and Uruguay, have already legalised it. Due to its controversial history, the medicinal use of cannabinoids has always been a centre of debate. The isolation and characterisation of Δ⁹ tetrahydrocannabinol (THC), the major psychoactive component of cannabis and the detection of two human cannabinoid receptor (CBRs) molecules renewed interest in the medical use of cannabinoids, boosting research and commercial heed in this sector. Some cannabinoid-based drugs have been approved as medications, mainly as antiemetic, antianorexic, anti-seizure remedies and in cancer and multiple sclerosis patients' palliative care. Nevertheless, due to the stigma commonly associated with these compounds, cannabinoids' potential in the treatment of conditions such as cancer is still largely unknown and therefore underestimated.