Patrizia Gazzerro

Pharmacological Actions of Statins: A Critical Appraisal in the Management of Cancer

Statins, among the most commonly prescribed drugs worldwide, are cholesterol-lowering agents used to manage and prevent cardiovascular and coronary heart diseases. Recently, a multifaceted action in different physiological and pathological conditions has been also proposed for statins, beyond anti-inflammation and neuroprotection. Statins have been shown to act through cholesterol-dependent and -independent mechanisms and are able to affect several tissue functions and modulate specific signal transduction pathways that could account for statin pleiotropic effects. Typically, statins are prescribed in middle-aged or elderly patients in a therapeutic regimen covering a long life span during which metabolic processes, aging, and concomitant novel diseases, including cancer, could occur. In this context, safety, toxicity, interaction with other drugs, and the state of health have to be taken into account in subjects treated with statins. Some evidence has shown a dichotomous effect of statins with either cancer-inhibiting or -promoting effects. To date, clinical trials failed to demonstrate a reduced cancer occurrence in statin users and no sufficient data are available to define the long-term effects of statin use over a period of 10 years. Moreover, results from clinical trials performed to evaluate the therapeutic efficacy of statins in cancer did not suggest statin use as chemotherapeutic or adjuvant agents. Here, we reviewed the pharmacology of the statins, providing a comprehensive update of the current knowledge of their effects on tissues, biological processes, and pathological conditions, and we dissected the disappointing evidence on the possible future use of statin-based drugs in cancer therapy.

Cannabinoids and cancer: pros and cons of an antitumour strategy

In the last two decades, research has dramatically increased the knowledge of cannabinoids biology and pharmacology. In mammals, compounds with properties similar to active components of Cannabis sativa, the so called ‘endocannabinoids’, have been shown to modulate key cell‐signalling pathways involved in cancer cell growth, invasion and metastasis. To date, cannabinoids have been licensed for clinical use as palliative treatment of chemotherapy, but increased evidences showed direct antiproliferative actions of cannabinoid agonists on several tumour cells in vitro and in animal models. In this article, we will review the principal molecular pathways modulated by cannabinoids on cancer and summarize pros and cons evidence on the possible future use of endocannabinoid‐based drugs in cancer therapy.

The Cannabinoid CB1 Receptor Antagonist Rimonabant (SR141716) Inhibits Human Breast Cancer Cell Proliferation through a Lipid Raft-Mediated Mechanism

The endocannabinoid system has been shown to modulate key cell-signaling pathways involved in cancer cell growth. In this study, we show that cannabinoid receptor type 1 (CB1) antagonist Rimonabant (SR141716) inhibited human breast cancer cell proliferation, being more effective in highly invasive metastatic MDA-MB-231 cells than in less-invasive T47D and MCF-7 cells. The SR141716 antiproliferative effect was not accompanied by apoptosis or necrosis and was characterized by a G1/S-phase cell cycle arrest, decreased expression of cyclin D and E, and increased levels of cyclin-dependent kinase inhibitor p27KIP1. We have also shown that SR141716 exerted a significant antiproliferative action, in vivo, by reducing the volume of xenograft tumors induced by MDA-MB-231 injection in mice. On the other hand, at the concentration range in which we observed the antiproliferative effect in tumor cells, we did not observe evidence of any genotoxic effect on normal cells. Our data also indicate that the SR141716 antiproliferative effect requires lipid raft/caveolae integrity to occur. Indeed, we found that CB1 receptor (CB1R) is completely displaced from lipid rafts in SR141716-treated MDA-MB-231 cells, and cholesterol depletion by methyl-β-cyclodextrin strongly prevented SR141716-mediated antiproliferative effect. Taken together, our results suggest that SR141716 inhibits human breast cancer cell growth via a CB1R lipid raft/caveolae-mediated mechanism.

The cannabinoid CB1 receptor antagonist rimonabant stimulates 2-deoxyglucose uptake in skeletal muscle cells by regulating the expression of phosphatidylinositol-3-kinase.

The endocannabinoid system regulates food intake, energy, and glucose metabolism at both central and peripheral levels. We have investigated the mechanism by which it may control glucose uptake in skeletal muscle cells. Detectable levels of the cannabinoid receptor type 1 (CB1) were revealed in L6 cells. Exposure of differentiated L6 myotubes to the CB1 antagonist rimonabant (SR141716) selectively increased 2-deoxyglucose uptake (2-DG) in a time- and dose-dependent manner. A similar effect was induced by genetic silencing of CB1 by small interfering RNA. Protein expression profiling revealed that both the regulatory p85 and the catalytic p110 subunits of the phosphatidylinositol-3-kinase (PI3K) were increased by SR141716. No significant change in the cellular content of other known molecules regulating PI3K was observed. However, phosphoinositide-dependent kinase-1, Akt/protein kinase B, and protein kinase Cζ activities were rapidly induced after SR141716 treatment of L6 cells in a PI3K-dependent manner. The stimulatory effect of SR141716 on PI3K expression and activity was largely prevented by N-[2-(4-bromocinnamylamino)ethyl]-5-isoquinoline (H-89), an inhibitor of the cAMP-dependent protein kinase. Moreover, SR141716-stimulated 2-DG uptake was blunted by the coincubation either with H-89 or with the PI3K inhibitor 2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride (LY294002), both in L6 cells and in mouse primary myocytes. Thus, modulation of CB1 regulates glucose uptake at the level of the PI3K signaling system in skeletal muscle cells. Interfering with CB1 signaling may therefore ameliorate glucoregulatory functions in peripheral tissues.

Association between cannabinoid type-1 receptor polymorphism and body mass index in a southern Italian population.

Context:Endocannabinoids control food intake via both central and peripheral mechanisms, and cannabinoid type-1 receptor (CB1) modulates lipogenesis in primary adipocyte cell cultures and in animal models of obesity.Objectives:We aimed to evaluate, at the population level, the frequency of a genetic polymorphism of CB1 and to study its correlation with body mass index.Design, setting and participants:Healthy subjects from a population survey carried out in southern Italy examined in 1992–1993 and older than 65 years (n=419, M=237, F=182) were divided into quintiles by body mass index (BMI). Two hundred and ten subjects were randomly sampled from the first, third and fifth quintile of BMI (BMI, respectively: 16.2–23.8=normal, 26.7–28.4=overweight, 31.6–49.7=obese) to reach a total of 70 per quintile. Their serum and white cells from the biological bank were used to measure the genotype and the blood variables for the study.Measurements:Anthropometric parameters, blood pressure, serum glucose and lipid levels were measured with standard methods; genotyping for the CB1 1359G/A polymorphism was performed using multiplex PCR. Statistical methods included χ 2 for trend, binomial and multinomial multiple logistic regression to model BMI on the genotype, controlling for potential confounders.Results:We found a clear trend of increasing relative frequency of the CB1 wild-type genotype with the increase of BMI (P=0.03) and, using a multiple logistic regression model, wild-type genotype, female gender, age, glycaemia and triglycerides were directly associated with both overweight (third quintile of BMI) and obesity (fifth quintile of BMI).Conclusions:Although performed in a limited number of subjects, our results show that the presence of the CB1 polymorphic allele was significantly associated with a lower BMI.

Plasma membrane and lysosomal localization of CB1 cannabinoid receptor are dependent on lipid rafts and regulated by anandamide in human breast cancer cells

In this report we show, by confocal analysis of indirect immunofluorescence, that the type‐1 cannabinoid receptor (CB1R), which belongs to the family of G‐protein‐coupled receptors, is expressed on the plasma membrane in human breast cancer MDA‐MB‐231 cells. However, a substantial proportion of the receptor is present in lysosomes. We found that CB1R is associated with cholesterol‐ and sphyngolipid‐enriched membrane domains (rafts). Cholesterol depletion by methyl‐β‐cyclodextrin (MCD) treatment strongly reduces the flotation of the protein on the raft‐fractions (DRM) of sucrose density gradients suggesting that CB1 raft‐association is cholesterol dependent. Interestingly binding of the agonist, anandamide (AEA) also impairs DRM‐association of the receptor suggesting that the membrane distribution of the receptor is dependent on rafts and is possibly regulated by the agonist binding. Indeed MCD completely blocked the clustering of CB1R at the plasma membrane. On the contrary the lysosomal localization of CB1R was impaired by this treatment only after AEA binding.

Antiangiogenic activity of the endocannabinoid anandamide: Correlation to its tumor-suppressor efficacy†

Endocannabinoids are now emerging as suppressors of key cell‐signaling pathways involved in cancer cell growth, invasion, and metastasis. We have previously observed that the metabolically stable anandamide analog, 2‐methyl‐2′‐F‐anandamide (Met‐F‐AEA) can inhibit the growth of thyroid cancer in vivo. Our hypothesis was that the anti‐tumor effect observed could be at least in part ascribed to inhibition of neo‐angiogenesis. Therefore, the aim of this study was to assess the anti‐angiogenic activity of Met‐F‐AEA, to investigate the molecular mechanisms underlying this effect and whether Met‐F‐AEA could antagonize tumor‐induced endothelial cell sprouting. We show that Met‐F‐AEA inhibited bFGF‐stimulated endothelial cell proliferation, in a dose‐dependent manner, and also induced apoptosis, both effects reliant on cannabinoid CB1 receptor stimulation. Analyzing the signaling pathways implicated in angiogenesis, we observed that the bFGF‐induced ERK phosphorylation was antagonized by Met‐F‐AEA, and we found that p38 MAPK was involved in Met‐F‐AEA‐induced apoptosis. Moreover, Met‐F‐AEA was able to inhibit bi‐dimensional capillary‐like tube formation and activity of matrix metalloprotease MMP‐2, a major matrix degrading enzyme. Importantly, we demonstrated that Met‐F‐AEA is also functional in vivo since it inhibited angiogenesis in the chick chorioallantoic neovascularization model. Finally, Met‐F‐AEA inhibited tumor‐induced angiogenesis in a three‐dimensional model of endothelial and thyroid tumor cell (KiMol) spheroids co‐cultures in different 3‐D polymeric matrices that resemble tumor microenvironment and architecture. Thus, our results suggest that anandamide could be involved in the control of cancer growth targeting both tumor cell proliferation and the angiogenic stimulation of the vasculature. J. Cell. Physiol. 211: 495–503, 2007.

Rimonabant: Just an Antiobesity Drug? Current Evidence on Its Pleiotropic Effects

The advent of the highly selective cannabinoid receptor (CB1) antagonist, rimonabant (SR141716; Acomplia) can revolutionize the ability of the clinicians to manage obesity. Large-scale clinical trials have demonstrated that rimonabant therapy can reduce obesity. Although, the precise mechanisms of action of rimonabant have to be further dissected, it is emerging, from both preclinical and clinical research, that not only is rimonabant an antiobesity drug, but also its pleiotropic functions affect a broad range of diseases, from obesity-related comorbidities to drug dependence and cancer. Here we review recent data from the literature and discuss the full pharmacological potential of this drug.

Investigation of CNR1 and FAAH endocannabinoid gene polymorphisms in bipolar disorder and major depression.

Experimental data suggest that the endogenous cannabinoid system is involved in mood regulation, but no study has been performed so far to investigate the role of endocannabinoid genes in the susceptibility to major depression (MD) and/or bipolar disorder (BD). We assessed the CB1 receptor gene (CNR1) single nucleotide polymorphism (SNP) rs1049353 (1359 G/A) and the fatty acid amide hydrolase (FAAH) gene rs324420 SNP (cDNA 385C to A) for their associations with MD and/or BD in 83 Caucasian patients with recurrent MD, 134 Caucasian individuals with BD, and 117 Caucasian healthy subjects. The distribution of the CNR1 1359 G/A genotypes and alleles significantly differed among the groups (chi(2)=12.595; df=4, P=0.01 for genotypes; chi(2)=13.773; df=2, P=0.001 for alleles) with MD patients showing a higher frequency of both AG, GG genotypes and A allele as compared to healthy controls. The distribution of the FAAH cDNA 385C to A genotypes, according to the CC dominant model (AA+AC vs. CC), significantly differed among the groups (chi(2)=6.626; df=2, P=0.04), with both BD patients and MD patients showing a non-significant slightly higher frequency of the AC genotype. These findings, although preliminary, suggest that the CNR1 1359 G/A and the FAAH cDNA 385C to A gene variants may contribute to the susceptibility to mood disorders.

Use of cannabinoid receptor agonists in cancer therapy as palliative and curative agents

Cannabinoids (the active components of Cannabis sativa) and their derivatives have received renewed interest in recent years due to their diverse pharmacological activities. In particular, cannabinoids offer potential applications as anti-tumour drugs, based on the ability of some members of this class of compounds to limit cell proliferation and to induce tumour-selective cell death. Although synthetic cannabinoids may have pro-tumour effects in vivo due to their immunosuppressive properties, predominantly inhibitory effects on tumour growth and migration, angiogenesis, metastasis, and also inflammation have been described. Emerging evidence suggests that agonists of cannabinoid receptors expressed by tumour cells may offer a novel strategy to treat cancer. In this chapter we review the more recent results generating interest in the field of cannabinoids and cancer, and provide novel suggestions for the development, exploration and use of cannabinoid agonists for cancer therapy, not only as palliative but also as curative drugs.