Monthly Archives: December 2012

Cannabinoid Receptor Agonist-induced Apoptosis of Human Prostate Cancer Cells LNCaP Proceeds through Sustained Activation of ERK1/2 Leading to G1 Cell Cycle Arrest

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“Prostate cancer (CaP)2 ranks as the most common noncutaneous malignancy and the second leading cause of cancer-related deaths in American males, with similar trends in many Western countries…The major cause of mortality from this disease is metastasis of hormone refractory cancer cells that fail to respond to hormone ablation therapy. Because surgery and current treatment options have proven to be inadequate in treating and controlling CaP, the search for novel targets and mechanism-based agents for prevention and treatment of this disease has become a priority.”

“In recent years, cannabinoids the active components of Cannabis sativa linnaeus (marijuana) and their derivatives are drawing renewed attention because of their diverse pharmacological activities such as cell growth inhibition, anti-inflammatory effects, and tumor regression. Further interest in cannabinoid research came from the discovery of the cannabinoid system and the cloning of specific cannabinoid receptors. Two cannabinoid receptors have been identified: the “central” CB1 and the “peripheral” CB2 receptor. In a recent study, we have shown that WIN 55,212-2 a mixed CB1/CB2 receptor agonist imparts cell growth inhibitory effects in LNCaP cells via an induction of apoptosis. An important observation of this study was that WIN 55,212-2 treatment did not result in apoptosis of the normal prostate epithelial cell at similar doses.”

“Cannabinoids and their derivatives are drawing considerable attention in the treatment of cancer because of their diverse activities such as cell growth inhibition, anti-inflammatory effects, and tumor regression. Accumulated evidence indicates that cannabinoid receptor(s) could be an important target for the treatment of cancer. We have earlier shown that WIN-55,212-2 induced apoptosis of prostate cancer LNCaP cells is mediated through CB1 and CB2 receptors and suggested that these receptors could be an important targets for the treatment of prostate cancer…”

“Hence, we conclude that cannabinoid receptor agonist should be considered as an effective agent for the treatment of prostate cancer. If our hypothesis is supported by in vivo experiments, the long term implications of our study could be to develop nonhabit-forming cannabinoid agonist (s) for the management of prostate cancer.”

http://www.jbc.org/content/281/51/39480.long

Delta9-tetrahydrocannabinol induces apoptosis in human prostate PC-3 cells via a receptor-independent mechanism.

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Abstract

“The effect of delta9-tetrahydrocannabinol (THC), the major psycho-active component of marijuana, in human prostate cancer cells PC-3 was investigated. THC caused apoptosis in a dose-dependent manner. Morphological and biochemical changes induced by THC in prostate PC-3 cells shared the characteristics of an apoptotic phenomenon. First, loss of plasma membrane asymmetry determined by fluorescent anexin V binding. Second, presence of apoptotic bodies and nuclear fragmentation observed by DNA staining with 4′,6-diamino-2-phenylindole (DAPI). Third, presence of typical ‘ladder-patterned’ DNA fragmentation. Central cannabinoid receptor expression was observed in PC-3 cells by immunofluorescence studies. However, several results indicated that the apoptotic effect was cannabinoid receptor-independent, such as lack of an effect of the potent cannabinoid agonist WIN 55,212-2, inability of cannabinoid antagonist AM 251 to prevent cellular death caused by THC and absence of an effect of pertussis toxin pre-treatment.”

http://www.ncbi.nlm.nih.gov/pubmed/10570948

CYCLOOXYGENASE-2 AND PEROXISOME PROLIFERATOR ACTIVATED RECEPTOR γ CONFER CANNABIDIOL-INDUCED APOPTOSIS OF HUMAN LUNG CANCER CELLS.

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Abstract

“The antitumorigenic mechanism of cannabidiol (CBD) is still controversial. This study investigates the role of cyclooxygenase-2 (COX-2) and peroxisome proliferator activated receptor γ (PPARγ) in CBDs proapoptotic and tumor-regressive action. In lung cancer cell lines (A549, H460) and primary cells from a lung cancer patient CBD elicited decreased viability associated with apoptosis. Apoptotic cell death by CBD was suppressed by NS-398 (COX-2 inhibitor), GW-9662 (PPARγ antagonist) and siRNA targeting COX-2 and PPARγ. CBD-induced apoptosis was paralleled by upregulation of COX-2 and PPARγ mRNA and protein expression with a maximum induction of COX-2 mRNA after 8 h and continuous increases of PPARγ mRNA when compared to vehicle. In response to CBD tumor cell lines exhibited increased levels of COX-2-dependent prostaglandins (PGs) among which PGD2 and 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2) caused a translocation of PPARγ to the nucleus and induced a PPARγ-dependent apoptotic cell death. Moreover, in A549-xenografted nude mice CBD caused upregulation of COX-2 and PPARγ in tumor tissue, and tumor regression that was fully reversible by GW-9662. Together, our data demonstrate a novel proapoptotic mechanism of CBD involving initial upregulation of COX-2 and PPARγ and a subsequent nuclear translocation of PPARγ by COX-2-dependent PGs.”

http://www.ncbi.nlm.nih.gov/pubmed/23220503

Neuroprotective agents: cannabinoids.

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Abstract

“Chronic inflammation and neurodegeneration are the main pathological traits of multiple sclerosis that coexist in all stages of the disease course, with complex and still nonclarified relationships. Currently licensed medications have efficacy to control aspects related to inflammation, but have been unable to modify pure progression. Experimental work has provided robust evidence of the immunomodulatory and neuroprotective properties that cannabinoids exert in animal models of multiple sclerosis. Through activation of the CB2 receptor, cannabinoids modulate peripheral blood lymphocytes, interfere with migration across the blood-brain barrier and control microglial/macrophage activation. CB1 receptors present in neural cells have a fundamental role in direct neuroprotection against several insults, mainly excitotoxicity. In multiple sclerosis, several reports have documented the disturbance of the endocannabinoid system. Considering the actions demonstrated experimentally, cannabinoids might be promising agents to target the main aspects of the human disease.”

http://www.ncbi.nlm.nih.gov/pubmed/21420365

The neuroprotective effect of cannabidiol in an in vitro model of newborn hypoxic-ischemic brain damage in mice is mediated by CB(2) and adenosine receptors.

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Abstract

“To investigate the mechanisms involved in cannabidiol (CBD)-induced neuroprotection in hypoxic-ischemic (HI) immature brain, forebrain slices from newborn mice underwent oxygen and glucose deprivation in the presence of vehicle, or CBD alone or with selective antagonists of cannabinoid CB(1) and CB(2), and adenosine A(1) and A(2) receptors. CBD reduced acute (LDH efflux to the incubation medium) and apoptotic (caspase-9 concentration in tissue) HI brain damage by reducing glutamate and IL-6 concentration, and TNFalpha, COX-2, and iNOS expression. CBD effects were reversed by the CB(2) antagonist AM630 and by the A(2A) antagonist SCH58261. The A(1A) antagonist DPCPX only counteracted the CBD reduction of glutamate release, while the CB(1) antagonist SR141716 did not modify any effect of CBD. In conclusion, CBD induces robust neuroprotection in immature brain, by acting on some of the major mechanisms underlying HI cell death; these effects are mediated by CB(2) and adenosine, mainly A(2A), receptors.”

http://www.ncbi.nlm.nih.gov/pubmed/19900555

Cannabinoids provide neuroprotection against 6-hydroxydopamine toxicity in vivo and in vitro: relevance to Parkinson’s disease.

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Abstract

“Cannabinoids have been reported to provide neuroprotection in acute and chronic neurodegeneration. In this study, we examined whether they are also effective against the toxicity caused by 6-hydroxydopamine, both in vivo and in vitro, which may be relevant to Parkinson’s disease (PD). First, we evaluated whether the administration of cannabinoids in vivo reduces the neurodegeneration produced by a unilateral injection of 6-hydroxydopamine into the medial forebrain bundle. As expected, 2 weeks after the application of this toxin, a significant depletion of dopamine contents and a reduction of tyrosine hydroxylase activity in the lesioned striatum were noted, and were accompanied by a reduction in tyrosine hydroxylase-mRNA levels in the substantia nigra. None of these events occurred in the contralateral structures. Daily administration of delta9-tetrahydrocannabinol (delta9-THC) during these 2 weeks produced a significant waning in the magnitude of these reductions, whereas it failed to affect dopaminergic parameters in the contralateral structures. This effect of delta9-THC appeared to be irreversible since interruption of the daily administration of this cannabinoid after the 2-week period did not lead to the re-initiation of the 6-hydroxydopamine-induced neurodegeneration. In addition, the fact that the same neuroprotective effect was also produced by cannabidiol (CBD), another plant-derived cannabinoid with negligible affinity for cannabinoid CB1 receptors, suggests that the antioxidant properties of both compounds, which are cannabinoid receptor-independent, might be involved in these in vivo effects, although an alternative might be that the neuroprotection exerted by both compounds might be due to their anti-inflammatory potential. As a second objective, we examined whether cannabinoids also provide neuroprotection against the in vitro toxicity of 6-hydroxydopamine. We found that the non-selective cannabinoid agonist HU-210 increased cell survival in cultures of mouse cerebellar granule cells exposed to this toxin. However, this effect was significantly lesser when the cannabinoid was directly added to neuronal cultures than when these cultures were exposed to conditioned medium obtained from mixed glial cell cultures treated with HU-210, suggesting that the cannabinoid exerted its major protective effect by regulating glial influence to neurons. In summary, our results support the view of a potential neuroprotective action of cannabinoids against the in vivo and in vitro toxicity of 6-hydroxydopamine, which might be relevant for PD. Our data indicated that these neuroprotective effects might be due, among others, to the antioxidant properties of certain plant-derived cannabinoids, or exerted through the capability of cannabinoid agonists to modulate glial function, or produced by a combination of both mechanisms.”

http://www.ncbi.nlm.nih.gov/pubmed/15837565

Neuroprotection by Δ9-Tetrahydrocannabinol, the Main Active Compound in Marijuana, against Ouabain-Induced In Vivo Excitotoxicity

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“These results provide evidence that the cannabinoid system can serve to protect the brain against neurodegeneration.”

“In summary, we have shown that in an in vivo model of neurodegeneration Δ9-THC reduces neuronal damage via a CB1-receptor-mediated mechanism. This holds in both the acute and late phase after induction of excitotoxicity. Δ9-THC inhibits astrogliosis via a non-CB1-receptor-controlled mechanism. The results strengthen the concept that the endogenous cannabinoid system may serve to establish a defense system for the brain. This system may be functional in several neurodegenerative diseases in which excitotoxicity is thought to play a role, such as amyotrophic lateral sclerosis, Huntington’s and Parkinson’s diseases, and also in acute neuronal damage as found in stroke and traumatic brain injury. It is conceivable that the endogenous cannabinoid system can be exploited for therapeutic interventions in these types of primarily incurable diseases.”

http://www.jneurosci.org/content/21/17/6475.long

The seek of neuroprotection: introducing cannabinoids.

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Abstract

“The cannabinoid system is constituted by some endogenous ligands (endocannabinoids), usually arachydonic acid derivatives, and their specific receptors. The endogenous cannabinoid system (ECS) is involved in the control of synaptic transmission, modulating memory, motivation, movement, nociception, appetite and thermoregulation. ECS also exert extraneural effects, mainly immunomodulation and vasodilation. Two cannabinoid receptors have been cloned so far: CB(1) receptors are expressed in the central nervous system (CNS) but can also be found in glial cells and in peripheral tissues; CB(1) receptors are Gi/o protein coupled receptors that modulate the activity of several plasma membrane proteins and intracellular signaling pathways. CB(2) receptors are also Gi/o protein-coupled receptors; although it is accepted that CB(2) receptors are not expressed in forebrain neurons, they have been described in activated glia. Some of the cannabinoids activate other receptors, for instance vanilloid receptors (TRPV1). Lately, the ECS is emerging as a natural system of neuroprotection. This consideration is based on some properties of cannabinoids as their vasodilatory effect, the inhibition of the release of excitotoxic amino acids and cytokines, and the modulation of oxidative stress and toxic production of nitric oxide. Such effects have been demonstrated in adult and newborn animal models of acute and chronic neurodegenerative conditions, and postulate cannabinoids as valuable neuroprotective agents. Patents related to cannabinoid receptors are also discussed.”

http://www.ncbi.nlm.nih.gov/pubmed/18221224

The therapeutic potential of the cannabinoids in neuroprotection.

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Abstract

“After thousands of years of interest the last few decades have seen a huge increase in our knowledge of the cannabinoids and their mode of action. Their potential as medical therapeutics has long been known. However, very real concerns over their safety and efficacy have lead to caution and suspicion when applying the legislature of modern medicine to these compounds. The ability of this diverse family of compounds to modulate neurotransmission and act as anti-inflammatory and antioxidative agents has prompted researchers to investigate their potential as neuroprotective agents. Indeed, various cannabinoids rescue dying neurones in experimental forms of acute neuronal injury, such as cerebral ischaemia and traumatic brain injury. Cannabinoids also provide symptomatic relief in experimental models of chronic neurodegenerative diseases, such as multiple sclerosis and Huntington’s disease. This preclinical evidence has provided the impetus for the launch of a number of clinical trials in various conditions of neurodegeneration and neuronal injury using compounds derived from the cannabis plant. Our understanding of cannabinoid neurobiology, however, must improve if we are to effectively exploit this system and take advantage of the numerous characteristics that make this group of compounds potential neuroprotective agents.”

http://www.ncbi.nlm.nih.gov/pubmed/12387700

Cannabinoids and neuroprotection.

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Abstract

“Cannabinoid compounds are endowed with pharmacological properties that make them interesting candidates for therapeutic development. These properties have been known since antiquity. However, in the last decade extremely important advances in the understanding of the physiology, pharmacology, and molecular biology of the cannabinoid system have given this field of research fresh impetus and have renewed the interest in the possible clinical exploitation of these compounds. In the present review we summarize the effects elicited, at the cellular level, by cannabinoids acting through receptor-dependent and receptor-independent mechanisms. These data suggest different ways by which cannabinoids may act as neuroprotective agents (prevention of excitotoxicity by inhibition of glutamate release, antioxidant effects, anti-inflammatory actions, etc.). The experimental evidence supporting these hypotheses are presented and discussed with regard to both preclinical and clinical studies in disease states such as cerebral ischemia, brain trauma, and Multiple Sclerosis.”

http://www.ncbi.nlm.nih.gov/pubmed/11831553