Phytocannabinoids for Cancer Therapeutics: Recent Updates and Future Prospects.

“Phytocannabinoids (pCBs) are lipid-soluble phytochemicals present in the plant, Cannabis sativa L. and non-cannabis plants which have a long history in traditional and recreational medicine.

The plant and constituents were central in the discovery of the endocannabinoid system, the most new target for drug discovery.

The endocannabinoid system includes two G protein-coupled receptors; the cannabinoid receptors-1 and -2 (CB1 and CB2) for marijuana’s psychoactive principle ∆(9)-tetrahydrocannabinol (∆9-THC), their endogenous small lipid ligands; namely anandamide (AEA) and 2-arachidonoylglycerol (2-AG), also known as endocannabinoids and the proteins for endocannabinoid biosynthesis and degradation such as fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL).

The endocannabinoid system has been suggested as a pro-homeostatic and pleiotropic signaling system activated in a time- and tissue-specific way during pathological conditions including cancer.

Targeting the CB1 receptors become a concern because of adverse psychotropic reactions. Hence, targeting the CB2 receptors or the endocannabinoid metabolizing enzyme by phytocannabinoids obtained from non-cannabis plant lacking psychotropic adverse reactions has garnered interest in drug discovery.

These pCBs derived from plants beyond cannabis appear safe and effective with a wider access and availability.

In recent years, several pCBs derived other than non-cannabinoid plants have been reported to bind to and functionally interact with cannabinoid receptors and appear promising candidate for drug development in cancer therapeutics.

Several of them also target the endocannabinoid metabolizing enzymes that control endocannabinoid levels. In this article, we summarize, critically discuss the updates and future prospects of the pCBs as novel and promising candidates for cancer therapeutics.”

http://www.ncbi.nlm.nih.gov/pubmed/26179998

http://www.thctotalhealthcare.com/category/cancer/

Endocannabinoid 2-arachidonylglycerol protects primary cultured neurons against LPS-induced impairments in rat caudate nucleus.

“Inflammation plays a pivotal role in the pathogenesis of many diseases in the central nervous system.

Caudate nucleus (CN), the largest nucleus in the brain, is also implicated in many neurological disorders.

2-Arachidonoylglycerol (2-AG), the most abundant endogenous cannabinoid and the true natural ligand for CB1 receptors, has been shown to exhibit neuroprotective effects through its anti-inflammatory action from proinflammatory stimuli in hippocampus.

In the present study, we discovered that 2-AG significantly protects CN neurons in culture against lipopolysaccharide (LPS)-induced inflammatory response.

Our study suggests the therapeutic potential of 2-AG for the treatment of some inflammation-induced neurological disorders and pain.”

http://www.ncbi.nlm.nih.gov/pubmed/24510751

Endocannabinoid 2-arachidonylglycerol protects primary cultured neurons against homocysteine-induced impairments in rat caudate nucleus through CB1 receptor.

“Homocysteine (Hcy) is a high risk factor for Alzheimer’s disease (AD). Caudate nucleus (CN), the major component of basal ganglia in the brain, is also involved in many neurological disorders.

2-Arachidonoylglycerol (2-AG), the true natural ligand for cannabinoid type-1 (CB1) receptors and the most abundant endogenous cannabinoid, has been shown to exhibit neuroprotective effects through its anti-inflammatory action from proinflammatory stimuli in the hippocampus and CN.

In the present work, we explored that 2-AG significantly protects CN neurons in culture against Hcy-induced response.

2-AG is capable of inhibiting elevation of Hcy-induced cyclooxygenase-2 expression associated with nuclear factor-kappaB/p38MAPK/ERK1/2 signaling pathway through CB1 receptors-dependent way in primary cultured CN neurons.

Our study reveals the therapeutic potential for 2-AG for the treatment of neurodegenerative diseases, such as AD.”

http://www.ncbi.nlm.nih.gov/pubmed/25007951

Effect of Homocysteine on Voltage-Gated Sodium Channel Currents in Primary Cultured Rat Caudate Nucleus Neurons and Its Modulation by 2-Arachidonylglycerol.

“Homocysteine (Hcy) is an important risk factor for Alzheimer’s disease (AD) and other neurodegenerative diseases. Caudate nucleus (CN), the largest nucleus in the brain, is also implicated in many neurological disorders.

2-Arachidonoylglycerol (2-AG), the most abundant endogenous cannabinoid, has been shown to exhibit neuroprotective effects from many stimuli in the central nervous system (CNS).

Furthermore, it has been reported that voltage-gated sodium channels (VGSCs) are the common targets of many neuronal damages and drugs.

However, it is still not clear whether VGSCs are involved in the neurotoxicity of Hcy and the neuroprotective effect of 2-AG in CN neurons. In the present study, whole-cell patch clamp recording was used to invest the action of Hcy on sodium currents in primary cultured rat CN neurons and its modulation by 2-AG.

The results showed that in cultured CN neurons, pathological concentration of Hcy (100 μM) significantly increased the voltage-gated sodium currents (I Na) and produced a hyperpolarizing shift in the activation-voltage curve of I Na.

The further data demonstrated 2-AG is capable of suppressing elevation of Hcy-induced increase in I Na and hyperpolarizing shift of activation curves most partly through CB1 receptor-dependent way.

Our study provides a better understanding of Hcy-associated neurological disorders and suggests the therapeutic potential for 2-AG for the treatment of these diseases.”

http://www.ncbi.nlm.nih.gov/pubmed/26179279

Opposing actions of endocannabinoids on cholangiocarcinoma growth: recruitment of Fas and Fas ligand to lipid rafts.

The Journal of Biological Chemistry

“Cholangiocarcinomas are devastating cancers of biliary origin with limited treatment options…

Marijuana and its derivatives have been used in medicine for many centuries, and presently there is an emerging renaissance in the study of the therapeutic effects of cannabinoids…

In addition, cannabinoids might be effective antitumoral agents because of their ability to inhibit the growth of various types of cancer cell lines in culture and in laboratory animals.

Modulation of the endocannabinoid system is being targeted to develop possible therapeutic strategies for a number of cancers; therefore, we evaluated the effects of the two major endocannabinoids, anandamide and 2-arachidonylglycerol, on numerous cholangiocarcinoma cell lines…

These findings suggest that modulation of the endocannabinoid system may be a target for the development of possible therapeutic strategies for the treatment of this devastating cancer.

Consistent with our observation that AEA has antiproliferative and proapoptotic properties, cannabinoids of various origins (endogenous, plant-derived, or synthetic analogues) have been shown to suppress cancer cell growth in vitro as well as in vivo.

In conclusion, we have clearly demonstrated opposing actions of the endocannabinoids AEA and 2-AG on cholangiocarcinoma cell proliferation and have shown that these actions are via a cannabinoid receptor-independent but lipid raft-mediated pathway. Furthermore we have shown that the antiproliferative/proapoptotic actions of AEA are mediated via an accumulation of ceramide and the recruitment of the Fas death receptor into the lipid rafts. Cholangiocarcinoma has a very poor prognosis and survival rate; therefore we propose that the development of novel therapeutic strategies aimed at modulating the endocannabinoid system or mimicking the mode of action of AEA would prove beneficial for the treatment of this devastating disease.”

http://www.jbc.org/content/282/17/13098.long

Endocannabinoid signaling in female reproductive events: a potential therapeutic target?

“Nearly 30 years after the discovery in 1964 of the psychoactive ingredient of cannabis (Cannabis sativa), Δ9-tetrahydrocannabinol, its endogenous counterparts were discovered and collectively termed endocannabinoids (eCBs): N-arachidonoylethanolamine (anandamide) in 1992 and 2-arachidonoylglycerol in 1995.

Since then, intense research has identified additional eCBs and an ensemble of proteins that bind, synthesize and degrade them, the so-called eCB system.

Altogether, these new compounds have been recognized as key mediators of several aspects of human pathophysiology, and in particular of female fertility.

Here, the main features of the eCB system are presented, in order to put in a better perspective the relevance of eCB signaling in virtually all steps of human reproduction and to highlight emerging hopes that elements of this system might indeed become novel targets to combat fertility problems.”

http://www.ncbi.nlm.nih.gov/pubmed/26126134

The endogenous cardiac cannabinoid system: a new protective mechanism against myocardial ischemia.

“The pharmacological (and recreational) effects of cannabis have been known for centuries.

However, it is only recently that one has identified two subtypes of G-protein-coupled receptors, namely CB1 and CB2-receptors, which mediate the numerous effects of delta9-tetrahydrocannabinol and other cannabinoids.

Logically, the existence of cannabinoid-receptors implies that endogenous ligands for these receptors (endocannabinoids) exist and exert a physiological role.

Hence, arachidonoylethanolamide (anandamide) and sn-2 arachidonoylglycerol, the first two endocannabinoids identified, are formed from plasma membrane phospholipids and act as CB1 and/or CB2 agonists.

The presence of both CB1 and CB2-receptors in the rat heart is noteworthy.

This endogenous cardiac cannabinoid system is involved in several phenomena associated with cardioprotective effects.

Endocannabinoids and synthetic cannabinoids, the latter through either CB1 or CB2-receptors, exert direct cardioprotective effects in rat isolated hearts.

The ability of cannabinoids to reduce infarct size has been confirmed in vivo in anesthetized mice and rats.

This latter effect appears to be mediated through CB2-receptors.

Thus, the endogenous cardiac cannabinoid system, through activation of CB2-receptors, appears to be an important mechanism of protection against myocardial ischemia.”

http://www.ncbi.nlm.nih.gov/pubmed/16618028

[Cardiovascular effects of cannabinoids].

“The psychoactive properties of cannabinoids, the biologically active constituents of the marijuana plant, have long been recognized. Recent research has revealed that cannabinoids elicit not only neurobehavioral, and immunological, but also profound cardiovascular effects.

Similar effects can be elicited by the endogenous ligand arachidonyl ethanolamine (anandamide) and 2-arachidonoyl-glycerol.

The biological effects of cannabinoids are mediated by specific receptors.

Two cannabinoid receptors have been identified so far: CB1-receptors are expressed by different cells of the brain and in peripheral tissues, while CB2-receptors were found almost exclusively in immune cells.

Through the use of a selective CB1 receptor antagonist and CB1 receptor-knockout mice the hypotensive and bradycardic effects of cannabinoids in rodents could be attributed to activation of peripheral CB1 receptors. In hemodynamic studies using the radioactive microsphere technique in anesthetized rats, cannabinoids were found to be potent CB1-receptor dependent vasodilators in the coronary and cerebrovascular beds.

Recent findings implicate the endogenous cannabinoid system in the pathomechanism of haemorrhagic, endotoxic and cardiogenic shock.

Finally, there is evidence that the extreme mesenteric vasodilation, portal hypertension and systemic hypotension present in advanced liver cirrhosis are also mediated by the endocannabinoid system.

These exciting, recent research developments indicate that the endogenous cannabinoid system plays an important role in cardiovascular regulation, and pharmacological manipulation of this system may offer novel therapeutic approaches in a variety of pathological conditions.”

Cannabinoid pharmacology in the cardiovascular system: potential protective mechanisms through lipid signalling.

“Cannabinoids include not only plant-derived compounds (of which delta9-tetrahydrocannabinol is the primary psychoactive ingredient of cannabis), but also synthetic agents and endogenous substances termed endocannabinoids which include anandamide (2-arachidonoylethanolamide) and 2-arachidonoylglycerol.

Cannabinoids act on specific, G-protein-coupled, receptors which are currently divided into two types, CB1 and CB2. Relatively selective agonists and antagonists for these receptors have been developed, although one agent (SR141716A) widely used as an antagonist at CB1 receptors has non-cannabinoid receptor-mediated effects at concentrations which are often used to define the presence of the CB1 receptor.

Both cannabinoid receptors are primarily coupled to Gi/o proteins and act to inhibit adenylyl cyclase. Stimulation of CB1 receptors also modulates the activity of K+ and Ca2+ channels and of protein kinase pathways including protein kinase B (Akt) which might mediate effects on apoptosis. CB, receptors may activate the extracellular signal-regulated kinase cascade through ceramide signalling.

Cannabinoid actions on the cardiovascular system have been widely interpreted as being mediated by CB1 receptors although there are a growing number of observations, particularly in isolated heart and blood vessel preparations, that suggest that other cannabinoid receptors may exist.

Interestingly, the currently identified cannabinoid receptors appear to be related to a wider family of lipid receptor, those for the lysophospholipids, which are also linked to Gi/o protein signalling.

Anandamide also activates vanilloid VR1 receptors on sensory nerves and releases the vasoactive peptide, calcitonin gene-related peptide (CGRP), which brings about vasodilatation through its action on CGRP receptors.

Current evidence suggests that endocannabinoids have important protective roles in pathophysiological conditions such as shock and myocardial infarction.

Therefore, their cardiovascular effects and the receptors mediating them are the subject of increasing investigative interest.”

http://www.ncbi.nlm.nih.gov/pubmed/15005177

Endocannabinoids drive the acquisition of an alternative phenotype in microglia.

“The ability of microglia to acquire diverse states of activation, or phenotypes, reflects different features that are determinant for their contribution to homeostasis in the adult CNS, and their activity in neuroinflammation, repair or immunomodulation.

Despite the widely reported immunomodulatory effects of cannabinoids in both the peripheral immune system and the CNS, less is known about how the endocannabinoid signaling system (eCBSS) influence the microglial phenotype.

The general aim of the present study was to investigate the role of endocannabinoids in microglia polarization by using microglia cell cultures.

We show that alternative microglia (M2a) and acquired deactivated microglia (M2c) exhibit changes in the eCB machinery that favor the selective synthesis of 2-AG and AEA, respectively.

Once released, these eCBs might be able to act through CB1 and/or CB2 receptors in order to influence the acquisition of an M2 phenotype.

We present three lines of evidence that the eCBSS is critical for the acquisition of the M2 phenotype: (i) M2 polarization occurs on exposure to the two main endocannabinoids 2-AG and AEA in microglia cultures; (ii)cannabinoid receptor antagonists block M2 polarization; and, (iii) M2 polarization is dampened in microglia from CB2 receptor knockout mice.

Taken together, these results indicate the interest of eCBSS for the regulation of microglial activation in normal and pathological conditions.”

http://www.ncbi.nlm.nih.gov/pubmed/26086345