Amphiregulin is a factor for resistance of glioma cells to cannabinoid-induced apoptosis

Amphiregulin in infectious diseases: Role, mechanism, and potential therapeutic targets

Amphiregulin (AREG) serves as a ligand for the epidermal growth factor receptor (EGFR) and is involved in vital biological functions, including inflammatory responses, tissue regeneration, and immune system function. Upon interaction with the EGFR, AREG initiates a series of signaling cascades necessary for several physiological activities, such as metabolism, cell cycle regulation, and cellular proliferation. Recent findings have provided evidence for the substantial role of AREG in maintaining the equilibrium of homeostasis in damaged tissues and preserving epithelial cell structure in the context of viral infections affecting the lungs. The development of resistance to influenza virus infection depends on the presence of type 1 cytokine responses. Following the eradication of the pathogen, the lungs are subsequently colonized by several cell types that are linked with type 2 immune responses. These cells contribute to the process of repairing and resolving the tissue injury and inflammation caused by infections. Following influenza infection, the activation of AREG promotes the regeneration of bronchial epithelial cells, enhancing the tissue's structural integrity and increasing the survival rate of infected mice. In the same manner, mice afflicted with influenza experience rapid mortality due to a subsequent bacterial infection in the pulmonary region when both bacterial and viral infections manifest concurrently inside the same host. The involvement of AREG in bacterial infections has been demonstrated. The gene AREG experiences increased transcriptional activity inside host cells in response to bacterial infections caused by pathogens such as Escherichia coli and Neisseria gonorrhea. In addition, AREG has been extensively studied as a mitogenic stimulus in epithelial cell layers. Consequently, it is regarded as a prospective contender that might potentially contribute to the observed epithelial cell reactions in helminth infection. Consistent with this finding, mice that lack the AREG gene exhibit a delay in the eradication of the intestinal parasite Trichuris muris. The observed delay is associated with a reduction in the proliferation rate of colonic epithelial cells compared to the infected animals in the control group. The aforementioned findings indicate that AREG plays a pivotal role in facilitating the activation of defensive mechanisms inside the epithelial cells of the intestinal tissue. The precise cellular sources of AREG in this specific context have not yet been determined. However, it is evident that the increased proliferation of the epithelial cell layer in infected mice is reliant on CD4+ T cells. The significance of this finding lies in its demonstration of the crucial role played by the interaction between immunological and epithelial cells in regulating the AREG-EGFR pathway. Additional research is necessary to delve into the cellular origins and signaling mechanisms that govern the synthesis of AREG and its tissue-protective properties, independent of infection.

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.

Cancer Treatment: Preclinical & Clinical

The first evidence that cannabinoids may have in vitro and in vivo antineoplastic activity against tumor cell lines and animal tumor models was published in the Journal of the National Cancer Institute nearly 50 years ago. Cannabinoids appear to induce apoptosis in rodent brain tumors by way of direct interaction with the cannabinoid receptor. They may inhibit angiogenesis and tumor cell invasiveness. Despite preclinical findings, attempts to translate the benefits from bench to bedside have been limited. This session provides a review of the basic science supporting the use of cannabinoids in gliomas, paired with the first randomized clinical trial of a cannabis-based therapy for glioblastoma multiforme. Another preclinical presentation reports the effects of cannabinoids on triple-negative breast cancer cell lines and how cannabidiol may affect tumors. The session's second human trial raises concerns about the use of botanical cannabis in patients with advanced cancer receiving immunotherapy suggesting inferior outcomes.

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.

The Evaluation of AREG, MMP-2, CHI3L1, GFAP, and OPN Serum Combined Value in Astrocytic Glioma Patients' Diagnosis and Prognosis

Gliomas account for approximately 70% of primary brain tumors in adults. Of all gliomas, grade IV astrocytoma, also called glioblastoma, has the poorest overall survival, with <5% of patients surviving five years after diagnosis. Due to the aggressiveness, lethal nature, and impaired surgical accessibility of the tumor, early diagnosis of the tumor and, in addition, prediction of the patient's survival time are important. We hypothesize that combining the protein level values of highly recognizable glioblastoma serum biomarkers could help to achieve higher specificity and sensitivity in predicting glioma patient outcome as compared to single markers. The aim of this study was to select the most promising astrocytoma patient overall survival prediction variables from five secretory proteins-glial fibrillary acidic protein (GFAP), matrix metalloproteinase-2 (MMP-2), chitinase 3-like 1 (CHI3L1), osteopontin (OPN), and amphiregulin (AREG)-combining them with routinely used tumor markers to create a Patient Survival Score calculation tool. The study group consisted of 70 astrocytoma patients and 31 healthy controls. We demonstrated that integrating serum CHI3L1 and OPN protein level values and tumor isocitrate dehydrogenase 1 IDH1 mutational status into one parameter could predict low-grade astrocytoma patients' two-year survival with 93.8% accuracy.

Knockdown of Amphiregulin Triggers Doxorubicin-Induced Autophagic and Apoptotic Death by Regulating Endoplasmic Reticulum Stress in Glioblastoma Cells

Glioblastoma multiforme (GBM) is the most common type of malignant brain tumor. The present standard treatment for GBM has not been effective; therefore, the prognosis remains dramatically poor and prolonged survival after treatment is still limited. The new therapeutic strategies are urgently needed to improve the treatment efficiency. Doxorubicin (Dox) has been widely used in the treatment of many cancers for decades. In recent years, with the advancement of delivery technology, more and more research indicates that Dox has the opportunity to be used in the treatment of GBM. Amphiregulin (AREG), a ligand of the epidermal growth factor receptor (EGFR), has been reported to have oncogenic effects in many cancer cell types and is implicated in drug resistance. However, the biological function and molecular mechanism of AREG in Dox treatment of GBM are still unclear. Here, we demonstrate that knockdown of AREG can boost Dox-induced endoplasmic reticulum (ER) stress to trigger activation in both autophagy and apoptosis in GBM cells, ultimately leading to cell death. To explore the importance of AREG in the clinic, we used available bioinformatics tools and found AREG is highly expressed in GBM tumor tissues that are associated with poor survival. In addition, we also used antibody array analysis to dissect pathways that are likely to be activated by AREG. Taken together, our results revealed AREG can serve as a potential therapeutic target and a promising biomarker in GBM.

Cannabinoids as anticancer therapeutic agents

The recent announcement of marijuana legalization in Canada spiked many discussions about potential health benefits of Cannabis sativa. Cannabinoids are active chemical compounds produced by cannabis, and their numerous effects on the human body are primarily exerted through interactions with cannabinoid receptor types 1 (CB1) and 2 (CB2). Cannabinoids are broadly classified as endo-, phyto-, and synthetic cannabinoids. In this review, we will describe the activity of cannabinoids on the cellular level, comprehensively summarize the activity of all groups of cannabinoids on various cancers and propose several potential mechanisms of action of cannabinoids on cancer cells.

Differential Gene Expression in Erlotinib-Treated Fibroblasts

BACKGROUND

Therapies targeting the epidermal growth factor receptor (EGFR) result in a painful rash, the most common and debilitating toxicity among patients with non-small cell lung cancer (NSCLC) who take EGFR tyrosine kinase inhibitor (TKI) therapy; however, predicting the development and the severity of the rash is difficult.

OBJECTIVE

The aim of this study was to examine how erlotinib-an EGFR TKI that NSCLC patients take to stop or slow tumor growth-altered the transcriptome of dermal fibroblasts.

METHODS

Dermal fibroblasts (ATCC PCS-201-012) were seeded in cell culture flasks, grown under standard conditions, and transferred to cell culture dishes. Cells were treated once daily for 3 days with erlotinib 100 nM (n = 5), erlotinib 1 μM (n = 5), vehicle 1 μM (dimethyl sulfoxide) (n = 5), or no treatment (n = 5). Total RNA was extracted using a standard TRIzol method and hybridized using Affymetrix GeneChip Human Genome U133 Plus 2.0 arrays. Raw intensities generated from the arrays were normalized using a Robust Multiarray Average method and analyzed using analysis of variance in Limma R software. Differentially expressed genes were analyzed using Ingenuity Pathway Analysis to identify canonical or noncanonical signaling pathways enriched in this dataset.

RESULTS

We selected genes for investigation based on their potential role in wound healing (AQP3), rash development (CCL2), fibroblast activation (PALLD), cancer and cancer progression (GDF-15, SLC7A11, MMP12, and DIRAS3), and cell cycle control (CDC6). We were able to validate four of these genes by both Western blot analysis and quantitative polymerase chain reaction (MMP12, CCL2, CDC6, and SLC7A11).

DISCUSSION

If found predictive of rash in future studies using patient samples, our findings may help to identify those at risk for severe rash so that (a) the dose of EGFR TKI therapy may be adjusted; (b) additional treatments for the rash can be developed; and/or (c) precise, patient-centered interventions can be developed so that patients with cancer can better self-manage their rash and adhere to EGFR TKI treatment.

Amphiregulin Regulates Phagocytosis-Induced Cell Death in Monocytes via EGFR and the Bcl-2 Protein Family

Neonates are extremely susceptible to bacterial infections, and evidences suggest that phagocytosis-induced cell death (PICD) is less frequently triggered in neonatal monocytes than in monocytes from adult donors. An insufficient termination of the inflammatory response, leading to a prolonged survival of neonatal monocytes with ongoing proinflammatory cytokine release, could be associated with the progression of various inflammatory diseases in neonates. Our previous data indicate that amphiregulin (AREG) is increasingly expressed on the cell surface of neonatal monocytes, resulting in remarkably higher soluble AREG levels after proteolytic shedding. In this study, we found that E. coli-infected neonatal monocytes show an increased phosphorylation of ERK, increased expression of Bcl-2 and Bcl-X_L, and reduced levels of cleaved caspase-3 and caspase-9 compared to adult monocytes. In both cell types, additional stimulation with soluble AREG further increased ERK activation and expression of Bcl-2 and Bcl-X_L and reduced levels of cleaved caspase-3 and caspase-9 in an EGFR-dependent manner. These data suggest that reduced PICD of neonatal monocytes could be due to reduced intrinsic apoptosis and that AREG can promote protection against PICD. This reduction of the intrinsic apoptosis pathway in neonatal monocytes could be relevant for severely prolonged inflammatory responses of neonates.

Secreted amphiregulin promotes vincristine resistance in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer. Despite advances in surgery, radiotherapy and chemotherapy, the overall 5‑year survival rate of patients with OSCC has not significantly improved. In addition, the prognosis of patients with advanced‑stage OSCC remains poor. Therefore, it is necessary to develop novel therapeutic modalities. Vincristine (VCR), a naturally occurring vinca alkaloid, is a classical microtubule‑destabilizing agent and is widely used in the treatment of a number of cancers. Despite the proven antitumor benefits of VCR treatment, one of the major reasons for the failure of treatment is drug resistance. Changes in the tumor microenvironment are responsible for cross‑talk between cells, which may facilitate drug resistance in cancers; secreted proteins may promote communication between cancer cells to induce the development of resistance. To identify the secreted proteins involved in VCR resistance, conditioned media was obtained, and an antibody array was conducted to screen a comprehensive secretion profile between VCR‑resistant (SAS‑VCR) and parental (SAS) OSCC cell lines. The results showed that amphiregulin (AREG) was highly expressed and secreted in SAS‑VCR cells. Pretreatment with exogenous recombinant AREG markedly increased drug resistance against VCR in OSCC cells, as assessed by an MTT assay. Colony formation, MTT and western blot assays were performed to investigate the effects of AREG knockdown on VCR sensitivity. The results indicated that AREG expression can regulate VCR resistance in OSCC cells; overexpression of AREG increased VCR resistance in parental cells, whereas AREG knockdown decreased the VCR resistance of resistant cells. In addition, it was also demonstrated that the glycogen synthase kinase‑3β pathway may be involved in AREG‑induced VCR resistance. These findings may provide rationale to combine VCR with blockade of AREG‑related pathways for the effective treatment of OSCC.

Valproic acid-induced amphiregulin secretion confers resistance to temozolomide treatment in human glioma cells

BACKGROUND

Glioblastoma multiforme (GBM) is the most severe type of primary brain tumor with a high mortality rate. Although extensive treatments for GBM, including resection, irradiation, chemotherapy and immunotherapy, have been tried, the prognosis is still poor. Temozolomide (TMZ), an alkylating agent, is a front-line chemotherapeutic drug for the clinical treatment of GBM; however, its effects are very limited because of the chemoresistance. Valproic acid (VPA), an antiepileptic agent with histone deacetylase inhibitor activity, has been shown to have synergistic effects with TMZ against GBM. The mechanism of action of VPA on TMZ combination therapy is still unclear. Accumulating evidence has shown that secreted proteins are responsible for the cross talking among cells in the tumor microenvironment, which may play a critical role in the regulation of drug responses.

METHODS

To understand the effect of VPA on secreted proteins in GBM cells, we first used the antibody array to analyze the cell culture supernatant from VPA-treated and untreated GBM cells. The results were further confirmed by lentivirus-mediated knockdown and exogenous recombinant administration.

RESULTS

Our results showed that amphiregulin (AR) was highly secreted in VPA-treated cells. Knockdown of AR can sensitize GBM cells to TMZ. Furthermore, pretreatment of exogenous recombinant AR significantly increased EGFR activation and conferred resistance to TMZ. To further verify the effect of AR on TMZ resistance, cells pre-treated with AR neutralizing antibody markedly increased sensitivity to TMZ. In addition, we also observed that the expression of AR was positively correlated with the resistance of TMZ in different GBM cell lines.

CONCLUSIONS

The present study aimed to identify the secreted proteins that contribute to the modulation of drug response. Understanding the full set of secreted proteins present in glial cells might help reveal potential therapeutic opportunities. The results indicated that AR may potentially serve as biomarker and therapeutic approach for chemotherapy regimens in GBM.

Epidermal growth factor receptor and ligand family expression and activity in glioblastoma

Epidermal growth factor family of receptor tyrosine kinases (ERBB) family cell surface receptors, including epidermal growth factor receptor (EGFR/ERBB1), are phosphorylated upon binding by various EGF family ligands and signal via multiple kinase pathways. EGFR signaling is enhanced because of mutational activation of EGFR in almost half of glioblastomas, the most common malignant primary brain tumor. Therapeutic targeting of EGFR in glioblastoma has remained largely unsuccessful. Here, we profiled nine long-term (LTC) and five glioma-initiating (GIC) cell lines for expression and activation of ERBB family receptors and expression of their ligands. Receptors and ligands were abundantly expressed, with patterns overall similar to glioblastoma expression profiles in vivo as deposited in The Cancer Genome Atlas database. No differences between LTC and GIC emerged. Irrespective of ligand or receptor expression, neither an EGFR antibody, erbitux, nor an EGFR tyrosine kinase inhibitor, gefitinib, were particularly active against LTC or GIC at clinically relevant concentrations. Self-renewal capacity of GIC was severely compromised by epidermal growth factor (EGF) withdrawal, but rescued by transforming growth factor alpha (TGF-α), although not by neuregulin-1 (NRG-1). Subcellular fractionation indicated high levels of nuclear phosphorylated EGFR in all LTC and GIC. In LN-229 cells, pERBB2 and pERBB3 were also detected in the nucleus. Nuclear pERBB2 was less sensitive, whereas pERBB3 was induced, in response to gefitinib. This study provides an extensive characterization of human glioma cell models, including stem-like models, with regard to ERBB receptor/ligand expression and signaling. Redundant signaling involving multiple ERBB family ligands and receptors may contribute to the challenges of developing more effective EGFR-targeted therapies for glioblastoma.

Space Invaders: Brain Tumor Exploitation of the Stem Cell Niche

Increasing evidence indicates that the adult neurogenic niche of the ventricular-subventricular zone (V-SVZ), beyond serving as a potential site of origin, affects the outcome of malignant brain cancers. Glioma contact with this niche predicts worse prognosis, suggesting a supportive role for the V-SVZ environment in tumor initiation or progression. In this review, we describe unique components of the V-SVZ that may permit or promote tumor growth within the region. Cell-cell interactions, soluble factors, and extracellular matrix composition are discussed, and the role of the niche in future therapies is explored. The purpose of this review is to highlight niche intrinsic factors that may promote or support malignant cell growth and maintenance, and point out how we might leverage these features to improve patient outcome.

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

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

Cannabinoids as Modulators of Cell Death: Clinical Applications and Future Directions

Endocannabinoids are bioactive lipids that modulate various physiological processes through G-protein-coupled receptors (CB1 and CB2) and other putative targets. By sharing the activation of the same receptors, some phytocannabinoids and a multitude of synthetic cannabinoids mimic the effects of endocannabinoids. In recent years, a growing interest has been dedicated to the study of cannabinoids properties for their analgesic, antioxidant, anti-inflammatory and neuroprotective effects. In addition to these well-recognized effects, various studies suggest that cannabinoids may affect cell survival, cell proliferation or cell death. These observations indicate that cannabinoids may play an important role in the regulation of cellular homeostasis and, thus, may contribute to tissue remodelling and cancer treatment. For a long time, the study of cannabinoid receptor signalling has been focused on the classical adenylyl cyclase/cyclic AMP/protein kinase A (PKA) pathway. However, this pathway does not totally explain the wide array of biological responses to cannabinoids. In addition, the diversity of receptors and signalling pathways that endocannabinoids modulate offers an interesting opportunity for the development of specific molecules to disturb selectively the endogenous system. Moreover, emerging evidences suggest that cannabinoids ability to limit cell proliferation and to induce tumour-selective cell death may offer a novel strategy in cancer treatment. This review describes the main properties of cannabinoids in cell death and attempts to clarify the different pathways triggered by these compounds that may help to understand the complexity of respective molecular mechanisms and explore the potential clinical benefit of cannabinoids use in cancer therapies.

Knockdown of NUPR1 inhibits the proliferation of glioblastoma cells via ERK1/2, p38 MAPK and caspase-3

Nuclear protein-1 (NUPR1), located on chromosome 16p11.2, is a stress response factor that plays an important role in the growth and migration of human malignant tumor cells. However, the role of NUPR1 in glioblastoma remains poorly understood. The expression level of NUPR1 was detected by quantitative real-time PCR and immunohistochemistry (IHC). Wound healing, MTT, cell counting and BrdU assays were used to analyze the migration and proliferation of glioblastoma cells after down-regulating NUPR1 expression using a lentiviral vector. FACS analysis and a signaling antibody array kit were used to detect the mechanism by which NUPR1 modulates cell cycle and apoptosis activities in glioblastoma cells. We confirmed that NUPR1 was up-regulated in glioblastoma tissues compared to NB tissues. Down-regulation of NUPR1 suppressed cell migration and proliferation, arrested the cell cycle in the G0/G1 phase and promoted apoptosis in U251 and U87 cells in vitro. Furthermore, the expression levels of phosphorylated ERK1/2, p38 MAPK and cleaved caspase-3 were decreased upon silencing NUPR1 expression in U251 and U87 cells. In summary, NUPR1 plays an important role in the growth and migration of human glioblastoma cells. Knockdown of NUPR1 suppressed glioblastoma cell growth by arresting the cell cycle and inducing cell apoptosis via decreases in the expression of ERK1/2, p38 MAPK and caspase-3.

Enhanced Expression of Trib3 during the Development of Myelin Breakdown in dmy Myelin Mutant Rats

The demyelination (dmy) rat exhibits hind limb ataxia and severe myelin breakdown in the central nervous system. The causative gene of dmy rats is the MRS2 magnesium transporter gene. Tribbles homolog 3 (Trib3) is a pseudokinase molecule that modifies certain signal pathways, and its expression is increased in response to various stresses. Here we sought to clarify the mechanism of myelin breakdown by focusing Trib3, which is remarkably up-regulated in dmy rats. The expression of Trib3 mRNA was significantly increased at 4, 5, 6, 7 and 8 weeks of age in the dmy rats, prior to the prominent myelin breakdown between 7 and 10 weeks of age. The expression level of Trib3 was increased concurrently with the progression of the clinical and pathological conditions in the dmy rats. Double immunofluorescence demonstrated that TRIB3 was mainly expressed in neurons and oligodendrocytes and localized in the Golgi apparatus. Our findings indicate that Trib3 may be associated with the pathogenic mechanism of dmy rats.

Nupr1/Chop signal axis is involved in mitochondrion-related endothelial cell apoptosis induced by methamphetamine

Methamphetamine (METH) abuse has been a serious global public health problem for decades. Previous studies have shown that METH causes detrimental effects on the nervous and cardiovascular systems. METH-induced cardiovascular toxicity has been, in part, attributed to its destructive effect on vascular endothelial cells. However, the underlying mechanism of METH-caused endothelium disruption has not been investigated systematically. In this study, we identified a novel pathway involved in endothelial cell apoptosis induced by METH. We demonstrated that exposure to METH caused mitochondrial apoptosis in human umbilical vein endothelial cells and rat cardiac microvascular endothelial cells in vitro as well as in rat cardiac endothelial cells in vivo. We found that METH mediated endothelial cell apoptosis through Nupr1–Chop/P53–PUMA/Beclin1 signaling pathway. Specifically, METH exposure increased the expression of Nupr1, Chop, P53 and PUMA. Elevated p53 expression raised up PUMA expression, which initiated mitochondrial apoptosis by downregulating antiapoptotic Bcl-2, followed by upregulation of proapoptotic Bax, resulting in translocation of cytochrome c (cyto c), an apoptogenic factor, from the mitochondria to cytoplasm and activation of caspase-dependent pathways. Interestingly, increased Beclin1, upregulated by Chop, formed a ternary complex with Bcl-2, thereby decreasing the dissociative Bcl-2. As a result, the ratio of dissociative Bcl-2 to Bax was also significantly decreased, which led to translocation of cyto c and initiated more drastic apoptosis. These findings were supported by data showing METH-induced apoptosis was significantly inhibited by silencing Nupr1, Chop or P53, or by PUMA or Beclin1 knockdown. Based on the present data, a novel mechanistic model of METH-induced endothelial cell toxicity is proposed. Collectively, these results highlight that the Nupr1–Chop/P53–PUMA/Beclin1 pathway is essential for mitochondrion-related METH-induced endothelial cell apoptosis and may be a potential therapeutic target for METH-caused cardiovascular toxicity. Future studies using knockout animal models are warranted to substantiate the present findings.

Anticancer mechanisms of cannabinoids

In addition to the well-known palliative effects of cannabinoids on some cancer-associated symptoms, a large body of evidence shows that these molecules can decrease tumour growth in animal models of cancer. They do so by modulating key cell signalling pathways involved in the control of cancer cell proliferation and survival. In addition, cannabinoids inhibit angiogenesis and decrease metastasis in various tumour types in laboratory animals. In this review, we discuss the current understanding of cannabinoids as antitumour agents, focusing on recent discoveries about their molecular mechanisms of action, including resistance mechanisms and opportunities for their use in combination therapy. Those observations have already contributed to the foundation for the development of the first clinical studies that will analyze the safety and potential clinical benefit of cannabinoids as anticancer agents.

The use of cannabinoids as anticancer agents

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

Cannabinoids as therapeutic agents in cancer: current status and future implications

The pharmacological importance of cannabinoids has been in study for several years. Cannabinoids comprise of (a) the active compounds of the Cannabis sativa plant, (b) endogenous as well as (c) synthetic cannabinoids. Though cannabinoids are clinically used for anti-palliative effects, recent studies open a promising possibility as anti-cancer agents. They have been shown to possess anti-proliferative and anti-angiogenic effects in vitro as well as in vivo in different cancer models. Cannabinoids regulate key cell signaling pathways that are involved in cell survival, invasion, angiogenesis, metastasis, etc. There is more focus on CB1 and CB2, the two cannabinoid receptors which are activated by most of the cannabinoids. In this review article, we will focus on a broad range of cannabinoids, their receptor dependent and receptor independent functional roles against various cancer types with respect to growth, metastasis, energy metabolism, immune environment, stemness and future perspectives in exploring new possible therapeutic opportunities.

Delta(9) -tetrahydrocannabinol and cannabidiol as potential curative agents for cancer: A critical examination of the preclinical literature

An Internet search with search words "cannabis cures cancer" produce a wealth of sites claiming that cannabis has this effect. These sites are freely accessible to the general public and thus contribute to public opinion. But do delta(9) -tetrahydrocannabinol (Δ(9) -THC) and cannabidiol (CBD) cure cancer? In the absence of clinical data other than a safety study and case reports, preclinical data should be evaluated in terms of its predictive value. Using a strict approach where only concentrations and/or models relevant to the clinical situation are considered, the current preclinical data do not yet provide robust evidence that systemically administered Δ(9) -THC will be useful for the curative treatment of cancer. There is more support for an intratumoral route of administration of higher doses of Δ(9) -THC. CBD produces effects in relevant concentrations and models, although more data are needed concerning its use in conjunction with other treatment strategies.

Endocannabinoids and Cancer

A large body of evidence shows that cannabinoids, in addition to their well-known palliative effects on some cancer-associated symptoms, can reduce tumour growth in animal models of cancer. They do so by modulating key cell signalling pathways involved in the control of cancer cell proliferation and survival. In addition, cannabinoids inhibit angiogenesis and cell proliferation in different types of tumours in laboratory animals. By contrast, little is known about the biological role of the endocannabinoid system in cancer physio-pathology, and several studies suggest that it may be over-activated in cancer. In this review, we discuss our current understanding of cannabinoids as antitumour agents, focusing on recent advances in the molecular mechanisms of action, including resistance mechanisms and opportunities for combination therapy approaches.

Towards the use of cannabinoids as antitumour agents

Various reports have shown that cannabinoids (the active components of marijuana and their derivatives) can reduce tumour growth and progression in animal models of cancer, in addition to their well-known palliative effects on some cancer-associated symptoms. This Opinion article discusses our current understanding of cannabinoids as antitumour agents, focusing on recent insights into the molecular mechanisms of action, including emerging resistance mechanisms and opportunities for combination therapy approaches. Such knowledge is required for the optimization of preclinical cannabinoid-based therapies and for the preliminary clinical testing that is currently underway.

Tribbles: 'puzzling' regulators of cell signalling

Sensing and interpreting extracellular signals in response to changes in the environment has been a fundamental feature of all life forms from the very beginning of evolution. To fulfil this function, networks of proteins have evolved, forming the intracellular signal transduction machinery. Whereas the appropriate control of these signal transduction systems is essential to homoeostasis, dysregulation of signalling leads to disease and often the death of the organism. The tribbles family of pseudokinases have emerged in recent years as key controllers of signal transduction via their interactions with several key kinases, ubiquitin ligases and transcription factors. In line with their role in regulating fundamentally important signalling pathways, members of the tribbles family have been implicated in the development of a range of human diseases. Whereas our mechanistic understanding of how these proteins contribute to disease is far from complete, the present paper attempts to summarize some of the most important recent developments in this field of research.

The multiple roles of amphiregulin in human cancer

Amphiregulin (AREG) is one of the ligands of the epidermal growth factor receptor (EGFR). AREG plays a central role in mammary gland development and branching morphogenesis in organs and is expressed both in physiological and in cancerous tissues. Various studies have highlighted the functional role of AREG in several aspects of tumorigenesis, including self-sufficiency in generating growth signals, limitless replicative potential, tissue invasion and metastasis, angiogenesis, and resistance to apoptosis. The oncogenic activity of AREG has already been described in the most common human epithelial malignancies, such as lung, breast, colorectal, ovary and prostate carcinomas, as well as in some hematological and mesenchymal cancers. Furthermore, AREG is also involved in resistance to several cancer treatments. In this review, we describe the various roles of AREG in oncogenesis and discuss its translational potential, such as the development of anti-AREG treatments, based on AREG activity. In the last decade, independent groups have reported successful but sometimes contradictory results in relation to the potential of AREG to serve as a prognostic and/or predictive marker for oncology, especially with regard to anti-EGFR therapies. Thus, we also discuss the potential usefulness of using AREG as a therapeutic target and validated biomarker for predicting cancer outcomes or treatment efficacy.

Stimulation of the midkine/ALK axis renders glioma cells resistant to cannabinoid antitumoral action

Identifying the molecular mechanisms responsible for the resistance of gliomas to anticancer treatments is an issue of great therapeutic interest. Δ(9)-Tetrahydrocannabinol (THC), the major active ingredient of marijuana, and other cannabinoids inhibit tumor growth in animal models of cancer, including glioma, an effect that relies, at least in part, on the stimulation of autophagy-mediated apoptosis in tumor cells. Here, by analyzing the gene expression profile of a large series of human glioma cells with different sensitivity to cannabinoid action, we have identified a subset of genes specifically associated to THC resistance. One of these genes, namely that encoding the growth factor midkine (Mdk), is directly involved in the resistance of glioma cells to cannabinoid treatment. We also show that Mdk mediates its protective effect via the anaplastic lymphoma kinase (ALK) receptor and that Mdk signaling through ALK interferes with cannabinoid-induced autophagic cell death. Furthermore, in vivo Mdk silencing or ALK pharmacological inhibition sensitizes cannabinod-resistant tumors to THC antitumoral action. Altogether, our findings identify Mdk as a pivotal factor involved in the resistance of glioma cells to THC pro-autophagic and antitumoral action, and suggest that selective targeting of the Mdk/ALK axis could help to improve the efficacy of antitumoral therapies for gliomas.

Tumour Cannabinoid CB(1) receptor and phosphorylated epidermal growth factor receptor expression are additive prognostic markers for prostate cancer

BACKGROUND

In cultured prostate cancer cells, down-regulation of epidermal growth factor receptor (EGFR) has been implicated in mediating the antiproliferative effect of the endogenous cannabinoid (CB) ligand anandamide. Using a well-characterised cohort of prostate cancer patients, we have previously reported that expression levels of phosphorylated EGFR (pEGFR-IR) and CB(1) receptor (CB(1)IR) in tumour tissue at diagnosis are markers of disease-specific survival, but it is not known whether the two markers interact in terms of their influence on disease severity at diagnosis and disease outcome.

METHODOLOGY/PRINCIPAL FINDINGS

Data from a cohort of 419 patients who were diagnosed with prostate cancer at transurethral resection for voiding difficulties was used. Scores for both tumour CB(1)IR and pEGFR-IR were available in the database. Of these, 235 had been followed by expectancy until the appearance of metastases. For patients scored for both parameters, Cox proportional-hazards regression analyses using optimal cut-off scores indicated that the two measures provided additional diagnostic information not only to each other, but to that provided by the tumour stage and the Gleason score. When the cases were divided into subgroups on the basis of these cut-off scores, the patients with both CB(1)IR and pEGFR-IR scores above their cut-off had a poorer disease-specific survival and showed a more severe pathology at diagnosis than patients with high pEGFR-IR scores but with CB(1)IR scores below the cut-off.

CONCLUSIONS/SIGNIFICANCE

These data indicate that a high tumour CB(1) receptor expression at diagnosis augments the deleterious effects of a high pEGFR expression upon disease-specific survival.

Fatty acid amide hydrolase in prostate cancer: association with disease severity and outcome, CB1 receptor expression and regulation by IL-4

Background

Recent data have indicated that there may be a dysregulation of endocannabinoid metabolism in cancer. Here we have investigated the expression of the endocannabinoid metabolising enzyme fatty acid amide hydrolase (FAAH) in a well characterised tissue microarray from patients diagnosed with prostate cancer at transurethral resection for voiding problems.

Methodology/Principal Findings

FAAH immunoreactivity (FAAH-IR) was assessed in formalin-fixed paraffin-embedded non-malignant and tumour cores from 412 patients with prostate cancer. CB₁ receptor immunoreactivity (CB₁IR) scores were available for this dataset. FAAH-IR was seen in epithelial cells and blood vessel walls but not in the stroma. Tumour epithelial FAAH-IR was positively correlated with the disease severity at diagnosis (Gleason score, tumour stage, % of the specimen that contained tumour) for cases with mid-range CB₁IR scores, but not for those with high CB₁IR scores. For the 281 cases who only received palliative therapy at the end stages of the disease, a high tumour epithelial FAAH-IR was associated with a poor disease-specific survival. Multivariate Cox proportional-hazards regression analyses indicated that FAAH-IR gave additional prognostic information to that provided by CB₁IR when a midrange, but not a high CB₁IR cutoff value was used. Interleukin-4 (IL-4) receptor IR was found on tumour epithelial cells and incubation of prostate cancer PC-3 and R3327 AT1 cells with IL-4 increased their FAAH activity.

Conclusions/Significance

Tumour epithelial FAAH-IR is associated with prostate cancer severity and outcome at mid-range, but not high, CB₁IR scores. The correlation with CB₁IR in the tumour tissue may be related to a common local dysregulation by a component of the tumour microenvironment.

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

The cannabinoid 1 (CB(1)) and cannabinoid 2 (CB(2)) receptor agonist Delta(9)-tetrahydrocannabinol (THC) has been shown to be a broad-range inhibitor of cancer in culture and in vivo, and is currently being used in a clinical trial for the treatment of glioblastoma. It has been suggested that other plant-derived cannabinoids, which do not interact efficiently with CB(1) and CB(2) receptors, can modulate the actions of Delta(9)-THC. There are conflicting reports, however, as to what extent other cannabinoids can modulate Delta(9)-THC activity, and most importantly, it is not clear whether other cannabinoid compounds can either potentiate or inhibit the actions of Delta(9)-THC. We therefore tested cannabidiol, the second most abundant plant-derived cannabinoid, in combination with Delta(9)-THC. In the U251 and SF126 glioblastoma cell lines, Delta(9)-THC and cannabidiol acted synergistically to inhibit cell proliferation. The treatment of glioblastoma cells with both compounds led to significant modulations of the cell cycle and induction of reactive oxygen species and apoptosis as well as specific modulations of extracellular signal-regulated kinase and caspase activities. These specific changes were not observed with either compound individually, indicating that the signal transduction pathways affected by the combination treatment were unique. Our results suggest that the addition of cannabidiol to Delta(9)-THC may improve the overall effectiveness of Delta(9)-THC in the treatment of glioblastoma in cancer patients.