Role of cannabinoid receptor CB2 in HER2 pro-oncogenic signaling in breast cancer

Molecular mechanisms of mTOR-mediated cisplatin response in tumor cells

Cisplatin (CDDP) is one of the main chemotherapeutic drugs that is widely used in many cancers. However, CDDP resistance is a frequent therapeutic challenge that reduces prognosis in cancer patients. Since, CDDP has noticeable side effects in normal tissues and organs, it is necessary to assess the molecular mechanisms associated with CDDP resistance to improve the therapeutic methods in cancer patients. Drug efflux, detoxifying systems, DNA repair mechanisms, and drug-induced apoptosis are involved in multidrug resistance in CDDP-resistant tumor cells. Mammalian target of rapamycin (mTOR), as a serine/threonine kinase has a pivotal role in various cellular mechanisms such as autophagy, metabolism, drug efflux, and cell proliferation. Although, mTOR is mainly activated by PI3K/AKT pathway, it can also be regulated by many other signaling pathways. PI3K/Akt/mTOR axis functions as a key modulator of drug resistance and unfavorable prognosis in different cancers. Regarding, the pivotal role of mTOR in CDDP response, in the present review we discussed the molecular mechanisms that regulate mTOR mediated CDDP response in tumor cells.

Cannabinoids and triple-negative breast cancer treatment

Triple-negative breast cancer (TNBC) accounts for about 10-20% of all breast cancer cases and is associated with an unfavorable prognosis. Until recently, treatment options for TNBC were limited to chemotherapy. A new successful systemic treatment is immunotherapy with immune checkpoint inhibitors, but new tumor-specific biomarkers are needed to improve patient outcomes. Cannabinoids show antitumor activity in most preclinical studies in TNBC models and do not appear to have adverse effects on chemotherapy. Clinical data are needed to evaluate efficacy and safety in humans. Importantly, the endocannabinoid system is linked to the immune system and immunosuppression. Therefore, cannabinoid receptors could be a potential biomarker for immune checkpoint inhibitor therapy or a novel mechanism to reverse resistance to immunotherapy. In this article, we provide an overview of the currently available information on how cannabinoids may influence standard therapy in TNBC.

The clinical and pathological significance of increased expression of the cannabinoid receptors CB-1R and CB-2R in patients with papillary thyroid carcinomas compared to benign thyroid lesions

INTRODUCTION

Papillary thyroid carcinoma is the most common malignancy of the endocrine system. Most papillary thyroid carcinoma patients enjoy excellent outcomes. However, in patients with biologically aggressive features, additional prognostic and predictive data may aid disease management. Dysregulation of the endocannabinoid system including the cannabinoid receptors 1 and 2 (CB-1R and CB-2R) during carcinogenesis has been extensively studied over the last few decades. The aim of this study was to evaluate immunohistochemically the expression levels of both receptors in patients with papillary thyroid carcinoma and benign diseases, and to compare these rates and the histopathologically and clinically prognostic features.

METHODS

The pathological materials and clinical data of 100 patients with papillary thyroid carcinoma and 40 with benign diseases were retrospectively re-evaluated. All tissues were immunohistochemically stained for CB-1R and CB-2R. The expression levels of CB-1R and CB-2R in papillary thyroid carcinomas, and benign lesions were recorded and compared with the pathological and clinical features.

RESULTS

The expression levels of both receptors were significantly higher in papillary thyroid carcinoma patients than in those with benign conditions (P = 0.001). CB-1R expression correlated with both extrathyroidal extension (P = 0.022) and capsular invasion (P = 0.001). CB-2R expression was associated with the risk group of the American Thyroid Association stratification system (P = 0.004).

CONCLUSION

Our study suggests that increased cannabinoid receptor expression contributes to thyroid carcinogenesis. The CB-2R expression level could provide additional information aiding risk management. Furthermore, the CB-1R and CB-2R antibodies might increase the accuracy of papillary thyroid carcinoma diagnosis when combined with the papillary thyroid carcinoma biomarkers assayed after fine-needle aspiration of neoplastic cells.

Exploring the 1,3-benzoxazine chemotype for cannabinoid receptor 2 as a promising anti-cancer therapeutic

The discovery of selective agonists of cannabinoid receptor 2 (CB2) is strongly pursued to successfully tuning endocannabinoid signaling for therapeutic purposes. However, the design of selective CB2 agonists is still challenging because of the high homology with the cannabinoid receptor 1 (CB1) and for the yet unclear molecular basis of the agonist/antagonist switch. Here, the 1,3-benzoxazine scaffold is presented as a versatile chemotype for the design of CB2 agonists from which 25 derivatives were synthesized. Among these, compound 7b5 (CB2 EC50 = 110 nM, CB1 EC50 > 10 μM) demonstrated to impair proliferation of triple negative breast cancer BT549 cells and to attenuate the release of pro-inflammatory cytokines in a CB2-dependent manner. Furthermore, 7b5 abrogated the activation of extracellular signal-regulated kinase (ERK) 1/2, a key pro-inflammatory and oncogenic enzyme. Finally, molecular dynamics studies suggested a new rationale for the in vitro measured selectivity and for the observed agonist behavior.

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.

Overexpression of cannabinoid receptor 2 is associated with human breast cancer proliferation, apoptosis, chemosensitivity and prognosis via the PI3K/Akt/mTOR signaling pathway

INTRODUCTION

The cannabinoid receptor 2 (CB2) is mainly involved in the immune system. However, although CB2 has been reported to play an anti-tumor function in breast cancer (BC), its specific mechanism in BC remains unclear.

METHODS

We examined the expression and prognostic significance of CB2 in BC tissues by qPCR, second-generation sequencing, western blot, and immunohistochemistry. We assessed the impacts of overexpression and a specific agonist of CB2 on the growth, proliferation, apoptosis, and drug resistance of BC cells in vitro and in vivo using CCK-8, flow cytometry, TUNEL staining, immunofluorescence, tumor xenografts, western blot, and colony formation assays.

RESULTS

CB2 expression was significantly lower in BC compared with paracancerous tissues. It was also highly expressed in benign tumors and ductal carcinoma in situ, and its expression was correlated with prognosis in BC patients. CB2 overexpression and treatment of BC cells with a CB2 agonist inhibited proliferation and promoted apoptosis, and these actions were achieved by suppressing the PI3K/Akt/mTOR signaling pathway. Moreover, CB2 expression was increased in MDA-MB-231 cell treated with cisplatin, doxorubicin, and docetaxel, and sensitivity to these anti-tumor drugs was increased in BC cells overexpressing CB2.

CONCLUSIONS

These findings reveal that CB2 mediates BC via the PI3K/Akt/mTOR signaling pathway. CB2 could be a novel target for the diagnosis and treatment of BC.

Identification of fatty acid amide hydrolase as a metastasis suppressor in breast cancer

Clinical management of breast cancer (BC) metastasis remains an unmet need as it accounts for 90% of BC-associated mortality. Although the luminal subtype, which represents >70% of BC cases, is generally associated with a favorable outcome, it is susceptible to metastatic relapse as late as 15 years after treatment discontinuation. Seeking therapeutic approaches as well as screening tools to properly identify those patients with a higher risk of recurrence is therefore essential. Here, we report that the lipid-degrading enzyme fatty acid amide hydrolase (FAAH) is a predictor of long-term survival in patients with luminal BC, and that it blocks tumor progression and lung metastasis in cell and mouse models of BC. Together, our findings highlight the potential of FAAH as a biomarker with prognostic value in luminal BC and as a therapeutic target in metastatic disease.

Endocannabinoid signaling in glioma

High-grade gliomas constitute the most frequent and aggressive form of primary brain cancer in adults. These tumors express cannabinoid CB₁ and CB₂ receptors, as well as other elements of the endocannabinoid system. Accruing preclinical evidence supports that pharmacological activation of cannabinoid receptors located on glioma cells exerts overt anti-tumoral effects by modulating key intracellular signaling pathways. The mechanism of this cannabinoid receptor-evoked anti-tumoral activity in experimental models of glioma is intricate and may involve an inhibition not only of cancer cell survival/proliferation, but also of invasiveness, angiogenesis, and the stem cell-like properties of cancer cells, thereby affecting the complex tumor microenvironment. However, the precise biological role of the endocannabinoid system in the generation and progression of glioma seems very context-dependent and remains largely unknown. Increasing our basic knowledge on how (endo)cannabinoids act on glioma cells could help to optimize experimental cannabinoid-based anti-tumoral therapies, as well as the preliminary clinical testing that is currently underway.

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.

Endocannabinoid-Binding Receptors as Drug Targets

Cannabis plant has been used from ancient times with therapeutic purposes for treating human pathologies, but the identification of the cellular and molecular mechanisms underlying the therapeutic properties of the phytocannabinoids, the active compounds in this plant, occurred in the last years of the past century. In the late 1980s and early 1990s, seminal studies demonstrated the existence of cannabinoid receptors and other elements of the so-called endocannabinoid system. These G protein-coupled receptors (GPCRs) are a key element in the functions assigned to endocannabinoids and appear to serve as promising pharmacological targets. They include CB₁, CB₂, and GPR55, but also non-GPCRs can be activated by endocannabinoids, like ionotropic receptor TRPV₁ and even nuclear receptors of the PPAR family. Their activation, inhibition, or simply modulation have been associated with numerous physiological effects at both central and peripheral levels, which may have therapeutic value in different human pathologies, then providing a solid experimental explanation for both the ancient medicinal uses of Cannabis plant and the recent advances in the development of cannabinoid-based specific therapies. This chapter will review the scientific knowledge generated in the last years around the research on the different endocannabinoid-binding receptors and their signaling mechanisms. Our intention is that this knowledge may help readers to understand the relevance of these receptors in health and disease conditions, as well as it may serve as the theoretical basis for the different experimental protocols to investigate these receptors and their signaling mechanisms that will be described in the following chapters.

Cannabis Use in Patients With Cancer: A Clinical Review

Cannabis use and interest continues to increase among patients with cancer and caregivers. High-quality research remains scant in many areas, causing hesitancy or discomfort among most clinical providers. Although we have limitations on hard outcomes, we can provide some guidance and more proactively engage in conversations with patients and family about cannabis. Several studies support the efficacy of cannabis for various cancer and treatment-related symptoms, such as chemotherapy-induced nausea and cancer pain. Although formulations and dosing guidelines for clinicians do not formally exist at present, attention to tetrahydrocannabinol concentration and understanding of risks with inhalation can reduce risk. Conflicting information exists on the interaction between cannabis and immunotherapy as well as estrogen receptor interactions. Motivational interviewing can help engage in more productive, less stigmatized conversations.

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.

Cannabinoid receptor 2 expression in early-stage non-small cell lung cancers identifies patients with good prognosis and longer survival

BACKGROUND

Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related death with a 5-year survival of only 21%. Reliable prognostic and/or predictive biomarkers are needed to improve NSCLC patient stratification, particularly in curative disease stages. Since the endogenous cannabinoid system is involved in both carcinogenesis and anticancer immune defense, we hypothesized that tumor tissue expression of cannabinoid 1 and 2 receptors (CB1 and CB2) may affect survival.

METHODS

Tumor tissue samples collected from 100 NSCLC patients undergoing radical surgery were analyzed for CB1 and CB2 gene and protein expression using the quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC). The gene and protein expression data were correlated with disease stage, histology, tumor grading, application of chemotherapy, and survival. Additional paired tumor and normal tissue samples of 10 NSCLC patients were analyzed independently for comparative analysis of CB1 and CB2 gene expression.

RESULTS

Patients with tumors expressing the CB2 gene had significantly longer overall survival (OS) (P<0.001), cancer specific survival (CSS) (P=0.002), and disease-free survival (DFS) (P<0.001). They also presented with fewer lymph node metastases at the time of surgery (P=0.011). A multivariate analysis identified CB2 tumor tissue gene expression as a positive prognostic factor for CSS [hazard ratio (HR) =0.274; P=0.013] and DFS (HR =0.322; P=0.009), and increased CSS. High CB2 gene and protein expression were detected in 79.6% and 31.5% of the tested tumor tissue samples, respectively. Neither CB1 gene nor CB1 or CB2 protein expression affected survival. When comparing paired tumor and tumor-free lung tissue samples, we observed reduced CB1 (P=0.008) and CB1 (P=0.056) gene expression in tumor tissues.

CONCLUSIONS

In NSCLC patients undergoing radical surgery, expression of the CB1 and CB2 receptor genes is significantly decreased in neoplastic versus tumor-free lung tissue. CB2 tumor tissue gene expression is strongly associated with longer survival (OS, CSS, DFS) and fewer lymph node metastases at the time of surgery. More studies are needed to evaluate its role as a biomarker in NSCLC and to investigate the potential use of CB2 modulators to treat or prevent lung cancers.

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.

Cannabis as a potential compound against various malignancies, legal aspects, advancement by exploiting nanotechnology and clinical trials

Various preclinical and clinical studies exhibited the potential of cannabis against various diseases, including cancer and related pain. Subsequently, many efforts have been made to establish and develop cannabis-related products and make them available as prescription products. Moreover, FDA has already approved some cannabis-related products, and more advancement in this aspect is still going on. However, the approved product of cannabis is in oral dosage form, which exerts various limitations to achieve maximum therapeutic effects. A considerable translation is on a hike to improve bioavailability, and ultimately, the therapeutic efficacy of cannabis by the employment of nanotechnology. Besides the well-known psychotropic effects of cannabis upon the use at high doses, literature has also shown the importance of cannabis and its constituents in minimising the lethality of cancer in the preclinical models. This review discusses the history of cannabis, its legal aspect, safety profile, the mechanism by which cannabis combats with cancer, and the advancement of clinical therapy by exploiting nanotechnology. A brief discussion related to the role of cannabinoid in various cancers has also been incorporated. Lastly, the information regarding completed and ongoing trials have also been elaborated.

Anti-cancer potential of cannabis terpenes in a taxol-resistant model of breast cancer

Chemotherapeutic resistance can limit breast cancer outcomes; therefore, the exploration of novel therapeutic options is warranted. Isolated compounds found in cannabis have previously been shown to exhibit anti-cancer effects, but little is known about their effects in resistant breast cancer. Our study aims to evaluate the effects of terpenes found in cannabis in in vitro chemotherapy-resistant model of breast cancer. We aimed to identify whether five terpenes found in cannabis produced anti-cancer effects, and if their effects were improved upon co-treatment with cannabinoids and flavonoids also found in cannabis. Nerolidol and β-caryophyllene produced the greatest cytotoxic effects, activated the apoptotic cascade and reduced cellular invasion. Combinations with the flavonoid kaempferol potentiated the cytotoxic effects of ocimene, terpinolene, and β-myrcene. Combinations of nerolidol and Δ9-tetrahydrocannabinol or cannabidiol produced variable responses ranging from antagonism and additivity to synergy, depending on concentrations used. Our results indicate that cannabis terpenes, alone or combined with cannabinoids and flavonoids, produced anti-cancer effects in chemotherapy-resistant breast cancer cell lines. This study is a first step in the identification of compounds that could have therapeutic potential in the treatment of resistant breast cancer.

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.

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.

Transcription Profile and Pathway Analysis of the Endocannabinoid Receptor Inverse Agonist AM630 in the Core and Infiltrative Boundary of Human Glioblastoma Cells

Background: We have previously reported that the endocannabinoid receptor inverse agonist AM630 is a potent inhibitor of isocitrade dehydrogenase-1 wild-type glioblastoma (GBM) core tumour cell proliferation. To uncover the mechanism behind the anti-tumour effects we have performed a transcriptional analysis of AM630 activity both in the tumour core cells (U87) and the invasive margin cells (GIN-8), the latter representing a better proxy of post-surgical residual disease. Results: The core and invasive margin cells exhibited markedly different gene expression profiles and only the core cells had high expression of a potential AM630 target, the CB1 receptor. Both cell types had moderate expression of the HTR2B serotonin receptor, a reported AM630 target. We found that the AM630 driven transcriptional response was substantially higher in the central cells than in the invasive margin cells, with the former driving the up regulation of immune response and the down regulation of cell cycle and metastatic pathways and correlating with transcriptional responses driven by established anti-neoplastics as well as serotonin receptor antagonists. Conclusion: Our results highlight the different gene sets involved in the core and invasive margin cell lines derived from GBM and an associated marked difference in responsiveness to AM630. Our findings identify AM630 as an anti-neoplastic drug in the context of the core cells, showing a high correlation with the activity of known antiproliferative drugs. However, we reveal a key set of similarities between the two cell lines that may inform therapeutic intervention.

Targeting the Endocannabinoidome in Pancreatic Cancer

Pancreatic Ductal adenocarcinoma (PDAC), the most common malignancy of the pancreas, is an aggressive and lethal form of cancer with a very high mortality rate. High heterogeneity, asymptomatic initial stages and a lack of specific diagnostic markers result in an end-stage diagnosis when the tumour has locally advanced or metastasised. PDAC is resistant to most of the available chemotherapy and radiation therapy treatments, making surgery the most potent curative treatment. The desmoplastic tumour microenvironment contributes to determining PDAC pathophysiology, immune response and therapeutic efficacy. The existing therapeutic approaches such as FDA-approved chemotherapeutics, gemcitabine, abraxane and folfirinox, prolong survival marginally and are accompanied by adverse effects. Several studies suggest the role of cannabinoids as anti-cancer agents. Cannabinoid receptors are known to be expressed in pancreatic cells, with a higher expression reported in pancreatic cancer patients. Therefore, pharmacological targeting of the endocannabinoid system might offer therapeutic benefits in pancreatic cancer. In addition, emerging data suggest that cannabinoids in combination with chemotherapy can increase survival in transgenic pancreatic cancer murine models. This review provides an overview of the regulation of the expanded endocannabinoid system, or endocannabinoidome, in PDAC and will explore the potential of targeting this system for novel anticancer approaches.

Cannabidiol (CBD) in Cancer Management

Simple Summary

Cannabidiol (CBD) is one of the main constituents of the plant Cannabis sativa. Surveys suggest that medicinal cannabis is popular amongst people diagnosed with cancer. CBD is one of the key constituents of cannabis, and does not have the potentially intoxicating effects that tetrahydrocannabinol (THC), the other key phytocannabinoid has. Research indicates the CBD may have potential for the treatment of cancer, including the symptoms and signs associated with cancer and its treatment. Preclinical research suggests CBD may address many of the pathways involved in the pathogenesis of cancers. Preclinical and clinical research also suggests some evidence of efficacy, alone or in some cases in conjunction with tetrahydrocannabinol (THC, the other key phytocannabinoid in cannabis), in treating cancer-associated pain, anxiety and depression, sleep problems, nausea and vomiting, and oral mucositis that are associated with cancer and/or its treatment. Studies also suggest that CBD may enhance orthodox treatments with chemotherapeutic agents and radiation therapy and protect against neural and organ damage. CBD shows promise as part of an integrative approach to the management of cancer.

Abstract

The plant Cannabis sativa has been in use medicinally for several thousand years. It has over 540 metabolites thought to be responsible for its therapeutic effects. Two of the key phytocannabinoids are cannabidiol (CBD) and tetrahydrocannabinol (THC). Unlike THC, CBD does not have potentially intoxicating effects. Preclinical and clinical research indicates that CBD has a wide range of therapeutic effects, and many of them are relevant to the management of cancer. In this article, we explore some of the potential mechanisms of action of CBD in cancer, and evidence of its efficacy in the integrative management of cancer including the side effects associated with its treatment, demonstrating its potential for integration with orthodox cancer care.

Cannabinoids, their cellular receptors, and effects on the invasive phenotype of carcinoma and metastasis

BACKGROUND

The morbidity and mortality of cancer are significantly impacted by the invasive and metastatic potential of particular subgroups of malignant cells within a tumor. The particular pre-metastatic properties of cancerous cells are thus a critical target for novel therapeutics in the oncology field. Cannabinoid molecules have been investigated in recent years in the context of invasion and metastasis of various malignancies, with varying effects reported in the literature.

RECENT FINDINGS

There was substantial variability in the findings reported by the literature of the effects of cannabinoid molecules on cancer cell invasion and metastasis. These effects varied depending on which ligand and which of the CB1, CB2, or GPR55 receptors were investigated. These findings suggest a role for the phenomenon of biased signaling in explaining the diversity of effects of cannabinoid molecules on cancer cell invasion.

CONCLUSION

While substantially more investigation is required into the effects of cannabinoid molecules on cancer cell invasion and metastasis, we describe in this review the significant diversity in the responses of cancer cells to cannabinoid molecules in terms of their invasive and metastatic capacities.

Probing GPCR Dimerization Using Peptides

G protein-coupled receptors (GPCRs) are the largest class of membrane proteins and the most common and extensively studied pharmacological target. Numerous studies over the last decade have confirmed that GPCRs do not only exist and function in their monomeric form but in fact, have the ability to form dimers or higher order oligomers with other GPCRs, as well as other classes of receptors. GPCR oligomers have become increasingly attractive to investigate as they have the ability to modulate the pharmacological responses of the receptors which in turn, could have important functional roles in diseases, such as cancer and several neurological & neuropsychiatric disorders. Despite the growing evidence in the field of GPCR oligomerisation, the lack of structural information, as well as targeting the 'undruggable' protein-protein interactions (PPIs) involved in these complexes, has presented difficulties. Outside the field of GPCRs, targeting PPIs has been widely studied, with a variety of techniques being investigated; from small-molecule inhibitors to disrupting peptides. In this review, we will demonstrate several physiologically relevant GPCR dimers and discuss an array of strategies and techniques that can be employed when targeting these complexes, as well as provide ideas for future development.

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.

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.

Cannabinoid Drugs-Related Neuroprotection as a Potential Therapeutic Tool Against Chemotherapy-Induced Cognitive Impairment

In recent years, and particularly associated with the increase of cancer patients’ life expectancy, the occurrence of cancer treatment sequelae, including cognitive impairments, has received considerable attention. Chemotherapy-induced cognitive impairments (CICI) can be observed not only during pharmacological treatment of the disease but also long after cessation of this therapy. The lack of effective tools for its diagnosis together with the limited treatments currently available for alleviation of the side-effects induced by chemotherapeutic agents, demonstrates the need of a better understanding of the mechanisms underlying the pathology. This review focuses on the comprehensive appraisal of two main processes associated with the development of CICI: neuroinflammation and oxidative stress, and proposes the endogenous cannabinoid system (ECS) as a new therapeutic target against CICI. The neuroprotective role of the ECS, well described in other cognitive-related neuropathologies, seems to be able to reduce the activation of pro-inflammatory cytokines involved in the neuroinflammatory supraspinal processes underlying CICI. This review also provides evidence supporting the role of cannabinoid-based drugs in the modulation of oxidative stress processes that underpin cognitive impairments, and warrant the investigation of endocannabinoid components, still unknown, that may mediate the molecular mechanism behind this neuroprotective activity. Finally, this review points forward the urgent need of research focused on the understanding of CICI and the investigation of new therapeutic targets.

Anticancer agents based on Plastoquinone analogs with N-phenylpiperazine: Structure-activity relationship and mechanism of action in breast cancer cells

2,3-Dimethyl-1,4-benzoquinones named as Plastoquinone (PQ) analogs have antiproliferative activity and are promising new members of molecules that can be used to cope with cancer. In an attempt to develop effective and potentially safe antiproliferative agents, previously reported twelve Plastoquinone analogs (PQ1-12) have been obtained to understand their antiproliferative profile. All PQ analogs have been selected by the National Cancer Institute (NCI) of Bethesda based on the NCI Developmental Therapeutics Program and tested against the panel of 60 cancer cell lines. Based on those studies, the cytotoxicity of the selected PQ analogs (PQ8, PQ9, PQ11, and PQ12) was determined using four breast cancer cell lines (MCF7, UACC-2087, MDA-MB-231, and MDA-MB-435) and a normal cell line (HaCaT). For better understanding, apoptosis induction, changes in cell proliferation, cell migration, and reactive oxygen species (ROS) generation were investigated for the selected PQ analog (PQ11) on MCF7 and UACC-2087 cell lines. According to the study results, PQ11 showed the most promising anticancer activity against MCF7 cell line through increased oxidative stress and apoptosis and suppression of cell proliferation. Based on the biological activity profile, we hypothesize that PQ11 could be a modulator of the cannabinoid 2 (CB2) receptor. Accordingly, we analyzed molecular level interaction of PQ11 with CB2 receptor through molecular docking simulation and it was also predicted to have a favorable ADMET profile. Overall, our findings suggest that integration of the N-phenylpiperazine moiety can be a good strategy for the structural optimization of PQ analogs as anticancer agents, especially in breast cancer.

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.

Association of Breast Tumour Expression of Cannabinoid Receptors CBR1 and CBR2 with Prognostic Factors and Survival in Breast Cancer Patients

Cannabinoid receptors (CBR) are potential therapeutic targets for breast cancer. However, the role of CBR in breast cancer survival remains poorly understood. Data from a prospective cohort of 522 women diagnosed with invasive breast cancer between 2010 and 2012 were analysed. Clinical and pathological features were retrieved from electronic medical records. CBR expression was measured by immunohistochemistry. Adjusted partial Spearman correlations and multivariate Cox models were used to estimate associations with breast cancer prognostic factors and survival, respectively. The median follow-up was 92.0 months (range 7.0-114.0). CBR expression was heterogenous in tumours. Cytoplasmic expression of CBR1 was positively correlated with lymph node invasion (r_s = 0.110; p = 0.0155) and positive status of the human epidermal growth factor receptor 2 (HER2) (r_s = 0.168; p = 0.0002), while nuclear CBR2 was negatively correlated with grade (r_s = -0.171; p = 0.0002) and positively correlated with oestrogen receptor and progesterone receptor-positive status (r_s = 0.173; p = 0.0002 and r_s = 0.121; p = 0.0084, respectively). High cytoplasmic expression of CBR2 was associated, with 13% higher locoregional and distant recurrences (HR = 1.13 [0.97-1.33]), though this association did not reach statistical significance. Although the few events occurring during follow-up may have limited the detection of significant associations, these results indicate that CBR expression in breast cancer deserves further investigation.

Cannabinoid receptor CB1 and CB2 interacting proteins: Techniques, progress and perspectives

Cannabinoid receptors 1 and 2 (CB₁ and CB₂) are implicated in a range of physiological processes and have gained attention as promising therapeutic targets for a number of diseases. Protein-protein interactions play an integral role in modulating G protein-coupled receptor (GPCR) expression, subcellular distribution and signaling, and the identification and characterization of these will not only improve our understanding of GPCR function and biology, but may provide a novel avenue for therapeutic intervention. A variety of techniques are currently being used to investigate GPCR protein-protein interactions, including Förster/fluorescence and bioluminescence resonance energy transfer (FRET and BRET), proximity ligation assay (PLA), and bimolecular fluorescence complementation (BiFC). However, the reliable application of these methodologies is dependent on the use of appropriate controls and the consideration of the physiological context. Though not as extensively characterized as some other GPCRs, the investigation of CB₁ and CB₂ interacting proteins is a growing area of interest, and a range of interacting partners have been identified to date. This review summarizes the current state of the literature regarding the cannabinoid receptor interactome, provides commentary on the methodologies and techniques utilized, and discusses future perspectives.

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.

Unveiling the mechanism of action behind the anti-cancer properties of cannabinoids in ER+ breast cancer cells: Impact on aromatase and steroid receptors

Breast cancer is the leading cause of cancer-related death in women worldwide. In the last years, cannabinoids have gained attention in the clinical setting and clinical trials with cannabinoid-based preparations are underway. However, contradictory anti-tumour properties have also been reported. Thus, the elucidation of the molecular mechanisms behind their anti-tumour efficacy is crucial to better understand its therapeutic potential. Considering this, our work aims to clarify the molecular mechanisms underlying the anti-cancer properties of the endocannabinoid anandamide (AEA) and of the phytocannabinoids, cannabidiol (CBD) and Δ⁹-tetrahydrocannabinol (THC), in estrogen receptor-positive (ER⁺) breast cancer cells that overexpress aromatase (MCF-7aro). Their in vitro effects on cell proliferation, cell death and activity/expression of aromatase, ERα, ERβ and AR were investigated. Our results demonstrated that cannabinoids disrupted MCF-7aro cell cycle progression. Unlike AEA and THC that induced apoptosis, CBD triggered autophagy to promote apoptotic cell death. Interestingly, all cannabinoids reduced aromatase and ERα expression levels in cells. On the other hand, AEA and CBD not only exhibited high anti-aromatase activity but also induced up-regulation of ERβ. Therefore, all cannabinoids, albeit by different actions, target aromatase and ERs, impairing, in that way, the growth of ER⁺ breast cancer cells, which is dependent on estrogen signalling. As aromatase and ERs are key targets for ER⁺ breast cancer treatment, cannabinoids can be considered as potential and attractive therapeutic compounds for this type of cancer, being CBD the most promising one. Thus, from an in vitro perspective, this work may contribute to the growing mass of evidence of cannabinoids and cannabinoids-based medicines as potential anti-cancer drugs.

UXT antisense RNA 1 sever as a novel prognostic long non-coding RNA in early stage pancreatic ductal adenocarcinoma patients after receiving pancreaticoduodenectomy

Objective: The principal objective of this project was to investigate the prognostic value of UXT antisense RNA 1 (UXT-AS1) in pancreatic ductal adenocarcinoma (PDAC), as well as its biological function mechanisms and the screening of targeted drugs using The Cancer Genome Atlas (TCGA) PDAC genome-wide RNA sequencing (RNA-seq) dataset.

Methods: We used TCGA 112 early stage PDAC patients to screen the prognostic value of UXT-AS1. Biological functions and mechanisms of UXT-AS1 were investigated by co-expression analysis, differentially expressed genes (DEGs) and gene set enrichment analysis, while targeted drug screening was investigated by connectivity Map (CMap).

Results: By analyzing the dataset from TCGA cohort, we found that UXT-AS1 was significantly up-regulated in pancreatic cancer tissues. Multivariate survival analysis demonstrated that PDAC patients with high UXT-AS1 expression had an unfavourable prognosis (adjusted P=0.033, HR=1.830, 95%CI=1.051-3.188). Genome-wide co-expression analysis and gene set enrichment analysis suggested that UXT-AS1 may act as a pivotal part in PDAC by participating in nuclear factor kappa beta, regulation of tumor necrosis factor, cell adhesion, T cell receptor signaling pathway, and numerous immune-related biological processes and signaling pathways. Functional enrichment analysis of DEGs between high- and low-UXT-AS1 expression groups suggested that these DEGs were significant enriched in B cell receptor complex, response to drug chemical carcinogenesis and drug metabolism-cytochrome P450. CMap analysis revealed that quipazine and terazosin may be targeted drugs for UXT-AS1 in PDAC.

Conclusion: Our current study has identified UXT-AS1 as a novel biomarker for the prognosis of early stage PDAC. We also clarified its biological functional mechanisms and identified two targeted drugs of UXT-AS1 in PDAC.

Relevance of Peroxisome Proliferator Activated Receptors in Multitarget Paradigm Associated with the Endocannabinoid System

Cannabinoids have shown to exert their therapeutic actions through a variety of targets. These include not only the canonical cannabinoid receptors CB1R and CB2R but also related orphan G protein-coupled receptors (GPCRs), ligand-gated ion channels, transient receptor potential (TRP) channels, metabolic enzymes, and nuclear receptors. In this review, we aim to summarize reported compounds exhibiting their therapeutic effects upon the modulation of CB1R and/or CB2R and the nuclear peroxisome proliferator-activated receptors (PPARs). Concomitant actions at CBRs and PPARα or PPARγ subtypes have shown to mediate antiobesity, analgesic, antitumoral, or neuroprotective properties of a variety of phytogenic, endogenous, and synthetic cannabinoids. The relevance of this multitargeting mechanism of action has been analyzed in the context of diverse pathologies. Synergistic effects triggered by combinatorial treatment with ligands that modulate the aforementioned targets have also been considered. This literature overview provides structural and pharmacological insights for the further development of dual cannabinoids for specific disorders.

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.

Cannabinoids in Medicine: Cancer, Immunity, and Microbial Diseases

Recently, there has been a growing interest in the medical applications of Cannabis plants. They owe their unique properties to a group of secondary metabolites known as phytocannabinoids, which are specific for this genus. Phytocannabinoids, and cannabinoids generally, can interact with cannabinoid receptors being part of the endocannabinoid system present in animals. Over the years a growing body of scientific evidence has been gathered, suggesting that these compounds have therapeutic potential. In this article, we review the classification of cannabinoids, the molecular mechanisms of their interaction with animal cells as well as their potential application in the treatment of human diseases. Specifically, we focus on the research concerning the anticancer potential of cannabinoids in preclinical studies, their possible use in cancer treatment and palliative medicine, as well as their influence on the immune system. We also discuss their potential as therapeutic agents in infectious, autoimmune, and gastrointestinal inflammatory diseases. We postulate that the currently ongoing and future clinical trials should be accompanied by research focused on the cellular and molecular response to cannabinoids and Cannabis extracts, which will ultimately allow us to fully understand the mechanism, potency, and safety profile of cannabinoids as single agents and as complementary drugs.

The Immune Endocannabinoid System of the Tumor Microenvironment

Leukocytes are part of the tumor microenvironment (TME) and are critical determinants of tumor progression. Because of the immunoregulatory properties of cannabinoids, the endocannabinoid system (ECS) may have an important role in shaping the TME. Members of the ECS, an entity that consists of cannabinoid receptors, endocannabinoids and their synthesizing/degrading enzymes, have been associated with both tumor growth and rejection. Immune cells express cannabinoid receptors and produce endocannabinoids, thereby forming an “immune endocannabinoid system”. Although in vitro effects of exogenous cannabinoids on immune cells are well described, the role of the ECS in the TME, and hence in tumor development and immunotherapy, is still elusive. This review/opinion discusses the possibility that the “immune endocannabinoid system” can fundamentally influence tumor progression. The widespread influence of cannabinoids on immune cell functions makes the members of the ECS an interesting target that could support immunotherapy.

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.

The pharmacological basis for application of cannabidiol in cancer chemotherapy

Chemotherapy is one of the therapeutic approaches for cancer treatment and has demonstrated great success with the introduction of selectively acting molecules against specific biomarkers of some types of tumors. Despite this success there is a large unmet need for novel therapies that provide effective control on the progression of advanced or drug-resistant cancer diseases. In this review, we briefly summarized our knowledge of cannabinoids and the endocannabinoid system, as possible agents for cancer therapy. We analyzed the anticancer properties and mechanism of action of cannabidiol (CBD), the main non-psychoactive cannabinoid received from hemp of Cannabis plant. Despite of data for pleiotropic effects of CBD, we here present the results for the efficacy of CBD in the modulation of different stages of cancer development. The analysis of the anticancer properties of CBD is made in relation to the proposed or newly discovered molecular targets of action. Thereafter, we consider the specific effects of CBD on primary tumors, their invasiveness and metastases, whether the influence on identified tumor markers in different types of tumors reflect the therapeutic potential of CBD. The studies reviewed herein indicate that CBD elicit activity through the cannabinoid receptor dependent and independent pathways. The processes such as ceramide production, ER-stress, autophagy and apoptosis, angiogenesis and matrix remodeling also appear to regulate the anticancer activity of CBD. So, the pharmacological basis for therapeutic application of CBD is constructed on the scientific data for its antitumor activity, extensively provided studies in vitro and in vivo in animal tumor models, and available data on the safety profile of clinically approved CBD products. We also try to reduce the deficits of our understanding in relation of pharmacological synergistic interactions of CBD with cytostatic drugs, where data remains limited. It is recognized that more studies for defining the specific molecular and signaling mechanisms of anticancer action of cannabinoids, particularly CBD, requires further evaluation. We believe that the therapeutic advantages of CBD are associated not only with its non-psychoactive behavior, but also are related to its influence on the important biochemical pathways and signal molecules, defining the genome instability and specific changes of the malignant tumor cells.

Cannabinoids: A Guide for Use in the World of Gastrointestinal Disease

Cannabinoids have been known as the primary component of cannabis for decades, but the characterization of the endocannabinoid system (ECS) in the 1990s opened the doors for cannabis' use in modern medicine. The 2 main receptors of this system, cannabinoid receptors 1 and 2, are found on cells of various tissues, with significant expression in the gastrointestinal (GI) tract. The characterization of the ECS also heralded the understanding of endocannabinoids, naturally occurring compounds synthesized in the human body. Via secondary signaling pathways acting on vagal nerves, nociceptors, and immune cells, cannabinoids have been shown to have both palliative and detrimental effects on the pathophysiology of GI disorders. Although research on the effects of both endogenous and exogenous cannabinoids has been slow due to the complicated legal history of cannabis, discoveries of cannabinoids' treatment potential have been found in various fields of medicine, including the GI world. Medical cannabis has since been offered as a treatment for a myriad of conditions and malignancies, including cancer, human immunodeficiency virus/acquired immunodeficiency syndrome, multiple sclerosis, chronic pain, nausea, posttraumatic stress disorder, amyotrophic lateral sclerosis, cachexia, glaucoma, and epilepsy. This article hopes to create an overview of current research on cannabinoids and the ECS, detail the potential advantages and pitfalls of their use in GI diseases, and explore possible future developments in this field.

Functionalized Cannabinoid Subtype 2 Receptor Ligands: Fluorescent, PET, Photochromic and Covalent Molecular Probes

Cannabinoid subtype 2 receptors (CB2 Rs) are G protein-coupled receptors (GPCRs) belonging to the endocannabinoid system, a complex network of signalling pathways leading to the regulation of key physiological processes. Interestingly, CB2 Rs are strongly up-regulated in pathological conditions correlated with the onset of inflammatory events like cancer and neurodegenerative diseases. Therefore, CB2 Rs represent an important biological target for therapeutic as well as diagnostic purposes. No CB2 R-selective drugs are yet on the market, thus underlining a that deeper comprehension of CB2 Rs' complex activation pathways and their role in the regulation of diseases is needed. Herein, we report an overview of pharmacological and imaging tools such as fluorescent, positron emission tomography (PET), photochromic and covalent selective CB2 R ligands. These molecular probes can be used in vitro as well as in vivo to investigate and explore the unravelled role(s) of CB2 Rs, and they can help to design suitable CB2 R-targeted drugs.

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.

Bioactive lipids, inflammation and chronic diseases

Endogenous bioactive lipids are part of a complex network that modulates a plethora of cellular and molecular processes involved in health and disease, of which inflammation represents one of the most prominent examples. Inflammation serves as a well-conserved defence mechanism, triggered in the event of chemical, mechanical or microbial damage, that is meant to eradicate the source of damage and restore tissue function. However, excessive inflammatory signals, or impairment of pro-resolving/anti-inflammatory pathways leads to chronic inflammation, which is a hallmark of chronic pathologies. All main classes of endogenous bioactive lipids - namely eicosanoids, specialized pro-resolving lipid mediators, lysoglycerophopsholipids and endocannabinoids - have been consistently involved in the chronic inflammation that characterises pathologies such as cancer, diabetes, atherosclerosis, asthma, as well as autoimmune and neurodegenerative disorders and inflammatory bowel diseases. This review gathers the current knowledge concerning the involvement of endogenous bioactive lipids in the pathogenic processes of chronic inflammatory pathologies.

Cannabinoids and Hormone Receptor-Positive Breast Cancer Treatment

Breast cancer (BC) is the most common cancer in women worldwide. Approximately 70–80% of BCs express estrogen receptors (ER), which predict the response to endocrine therapy (ET), and are therefore hormone receptor-positive (HR+). Endogenous cannabinoids together with cannabinoid receptor 1 and 2 (CB1, CB2) constitute the basis of the endocannabinoid system. Interactions of cannabinoids with hypothalamic–pituitary–gonadal axis hormones are well documented, and two studies found a positive correlation between peak plasma endogenous cannabinoid anandamide with peak plasma 17β-estradiol, luteinizing hormone and follicle-stimulating hormone levels at ovulation in healthy premenopausal women. Do cannabinoids have an effect on HR+ BC? In this paper we review known and possible interactions between cannabinoids and specific HR+ BC treatments. In preclinical studies, CB1 and CB2 agonists (i.e., anandamide, THC) have been shown to inhibit the proliferation of ER positive BC cell lines. There is less evidence for antitumor cannabinoid action in HR+ BC in animal models and there are no clinical trials exploring the effects of cannabinoids on HR+ BC treatment outcomes. Two studies have shown that tamoxifen and several other selective estrogen receptor modulators (SERM) can act as inverse agonists on CB1 and CB2, an interaction with possible clinical consequences. In addition, cannabinoid action could interact with other commonly used endocrine and targeted therapies used in the treatment of HR+ BC.

The Endocannabinoid System: A Target for Cancer Treatment

In recent years, the endocannabinoid system has received great interest as a potential therapeutic target in numerous pathological conditions. Cannabinoids have shown an anticancer potential by modulating several pathways involved in cell growth, differentiation, migration, and angiogenesis. However, the therapeutic efficacy of cannabinoids is limited to the treatment of chemotherapy-induced symptoms or cancer pain, but their use as anticancer drugs in chemotherapeutic protocols requires further investigation. In this paper, we reviewed the role of cannabinoids in the modulation of signaling mechanisms implicated in tumor progression.

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.

Genetic landscape of prognostic value in pancreatic ductal adenocarcinoma microenvironment

Background

The prognosis of pancreatic ductal adenocarcinoma (PDAC) remains dismally poor and is widely considered as an intricate genetic disorder. The mutational landscape of PDAC may directly reflect cancer immunogenicity and dictate the extent and phenotype of immune cell infiltration. In adverse, the microenvironment may also effect the gene expression of cancer cells, which is associated with clinical prognosis. Thus, it is crucial to identify genomic alterations in PDAC microenvironment and its impacts on clinical prognosis.

Methods

The gene expression profiles, mutation data and clinical information of 179 pancreatic cancer patients with an initial pathologic diagnosis ranging from 2001 to 2013 were retrieved from The Cancer Genome Atlas (TCGA) database. The MAlignant Tumor tissues using Expression data (ESTIMATE) algorithm for calculating immune scores and stromal scores and Tumor IMmune Estimation Resource (TIMER) resource for cell infiltrations were applied in this study.

Results

The average immune score or stromal score of PDAC subtype was significantly higher than that of other specific subtypes. KRAS mutant cases had significantly lower immune scores (P=0.001) and stromal scores (P=0.007), in concert with lower immune scores in TP53 mutant cases (P=0.030). However, no significant difference was found in SMAD4 and CDKN2A mutations. In the cohort OS/RFS, the infiltration levels of CD8+ T cells, B cells, Macrophages, Neutrophils and DCs in high stromal score group were higher than those in the low score group (all P<0.001), as well as in immune score groups except for Macrophages in the cohort RFS. In the cohort OS/RFS, 317/379 upregulated genes and 9/6 downregulated genes were observed in the high immune score group, while 227/205 upregulated genes and 17/6 downregulated genes in the high stromal score group. With the analysis for prognostic value of DEGs, 82 and 58 DEGs respectively in the high immune and stromal score group were verified to be significantly associated with better OS (P<0.05), while 53 and 17 DEGs respectively with longer RFS (P<0.05). Functional enrichment analysis showed genes of prognostic values were significantly related to immune response.

Conclusions

A list of genes with prognostic value in PDAC microenvironment were obtained from functional enrichment analysis based on immune and stromal scores, which indicates a series of potential auxiliary prognostic biomarkers for PDAC are available. Further research on these genes may be valuable and helpful to understand the crosstalk between tumor and microenvironment, new immune evasion mechanisms and underlying novel therapeutic targets in an integrated manner.