The endocannabinoid system and cancer: therapeutic implication

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“The endocannabinoid system is implicated in a variety of physiological and pathological conditions (inflammation, immunomodulation, analgesia, cancer and others).

The main active ingredient of cannabis, Δ(9) -tetrahydrocannabinol (Δ(9) -THC), produces its effects through activation of CB(1) and CB(2) receptors. CB(1) receptors are expressed at high levels in the central nervous system (CNS), whereas CB(2) receptors are concentrated predominantly, although not exclusively, in cells of the immune system.

Endocannabinoids are endogenous lipid-signalling molecules that are generated in the cell membrane from phospholipid precursors. The two best characterized endocannabinoids identified to date are anandamide (AEA) and 2-arachidonoylglycerol (2-AG). Here we review the relationship between the endocannabinoid system and anti-tumour actions (inhibition of cell proliferation and migration, induction of apoptosis, reduction of tumour growth) of the cannabinoids in different types of cancer.

This review will focus on examining how activation of the endocannabinoid system impacts breast, prostate and bone cancers in both in vitro and in vivo systems. The therapeutic potential of cannabinoids for cancer, as identified in clinical trials, is also discussed.

Identification of safe and effective treatments to manage and improve cancer therapy is critical to improve quality of life and reduce unnecessary suffering in cancer patients. In this regard, cannabis-like compounds offer therapeutic potential for the treatment of breast, prostate and bone cancer in patients.

Further basic research on anti-cancer properties of cannabinoids as well as clinical trials of cannabinoid therapeutic efficacy in breast, prostate and bone cancer is therefore warranted.” http://www.ncbi.nlm.nih.gov/pubmed/21410463

“The available literature suggests that the endocannabinoid system may be targeted to suppress the evolution and progression of breast, prostate and bone cancer as well as the accompanying pain syndromes. Many in vitro and in vivo studies have shown that cannabinoids are efficacious in reducing cancer progression (i.e. inhibition of tumour growth and metastases as well as induction of apoptosis and other anti-cancer properties) in breast, prostate and bone cancer. Although this review focuses on these three types of cancer, activation of the endocannabinoid signalling system produces anti-cancer effects in other types of cancer.” http://onlinelibrary.wiley.com/doi/10.1111/j.1476-5381.2011.01327.x/full

Delta9-tetrahydrocannabinol inhibits cell cycle progression in human breast cancer cells through Cdc2 regulation.

“It has been proposed that cannabinoids are involved in the control of cell fate. Thus, these compounds can modulate proliferation, differentiation, and survival in different manners depending on the cell type and its physiopathologic context. However, little is known about the effect of cannabinoids on the cell cycle, the main process controlling cell fate. Here, we show that Delta(9)-tetrahydrocannabinol (THC), through activation of CB(2) cannabinoid receptors, reduces human breast cancer cell proliferation by blocking the progression of the cell cycle and by inducing apoptosis. In particular, THC arrests cells in G(2)-M via down-regulation of Cdc2, as suggested by the decreased sensitivity to THC acquired by Cdc2-overexpressing cells. Of interest, the proliferation pattern of normal human mammary epithelial cells was much less affected by THC. We also analyzed by real-time quantitative PCR the expression of CB(1) and CB(2) cannabinoid receptors in a series of human breast tumor and nontumor samples. We found a correlation between CB(2) expression and histologic grade of the tumors. There was also an association between CB(2) expression and other markers of prognostic and predictive value, such as estrogen receptor, progesterone receptor, and ERBB2/HER-2 oncogene. Importantly, no significant CB(2) expression was detected in nontumor breast tissue. Taken together, these data might set the bases for a cannabinoid therapy for the management of breast cancer.

Breast cancer is the most common malignant disease among Western women. Although the rates of mortality of breast cancer patients have decreased as a result of early diagnosis by mammograms, certain breast tumors remain reluctant to conventional therapies, and current treatments have side effects that substantially affect the patient’s quality of life. Our findings might set the basis for new strategies for the management of breast cancer.”

http://cancerres.aacrjournals.org/content/66/13/6615.long

Synthetic cannabinoid receptor agonists inhibit tumor growth and metastasis of breast cancer.

“Cannabinoids have been reported to possess antitumorogenic activity. Not much is known, however, about the effects and mechanism of action of synthetic nonpsychotic cannabinoids on breast cancer growth and metastasis. We have shown that the cannabinoid receptors CB1 and CB2 are overexpressed in primary human breast tumors compared with normal breast tissue. We have also observed that the breast cancer cell lines MDA-MB231, MDA-MB231-luc, and MDA-MB468 express CB1 and CB2 receptors. Furthermore, we have shown that the CB2 synthetic agonist JWH-133 and the CB1 and CB2 agonist WIN-55,212-2 inhibit cell proliferation and migration under in vitro conditions. These results were confirmed in vivo in various mouse model systems. Mice treated with JWH-133 or WIN-55,212-2 showed a 40% to 50% reduction in tumor growth and a 65% to 80% reduction in lung metastasis. These effects were reversed by CB1 and CB2 antagonists AM 251 and SR144528, respectively, suggesting involvement of CB1 and CB2 receptors. In addition, the CB2 agonist JWH-133 was shown to delay and reduce mammary gland tumors in the polyoma middle T oncoprotein (PyMT) transgenic mouse model system. Upon further elucidation, we observed that JWH-133 and WIN-55,212-2 mediate the breast tumor-suppressive effects via a coordinated regulation of cyclooxygenase-2/prostaglandin E2 signaling pathways and induction of apoptosis. These results indicate that CB1 and CB2 receptors could be used to develop novel therapeutic strategies against breast cancer growth and metastasis.”

http://www.ncbi.nlm.nih.gov/pubmed/19887554

7-Oxo-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxamides as Selective CB2 Cannabinoid Receptor Ligands: Structural Investigations around a Novel Class of Full Agonists

“Cannabinoid receptor agonists have gained attention as potential therapeutic targets of inflammatory and neuropathic pain. Here, we report the identification and optimization of a series of 7-oxo-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxamide derivatives as a novel chemotype of selective cannabinoid CB2 receptor agonists… 7-Oxo-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxamides as Selective CB2 Cannabinoid Receptor Ligands: Structural Investigations around a Novel Class of Full Agonists.”

http://www.ncbi.nlm.nih.gov/pubmed/22738271

Cannabidiol protects oligodendrocyte progenitor cells from inflammation-induced apoptosis by attenuating endoplasmic reticulum stress

“Cannabidiol (CBD) is the most abundant cannabinoid in Cannabis sativa that has no psychoactive properties. CBD has been approved to treat inflammation, pain and spasticity associated with multiple sclerosis (MS), of which demyelination and oligodendrocyte loss are hallmarks. Thus, we investigated the protective effects of CBD against the damage to oligodendrocyte progenitor cells (OPCs) mediated by the immune system… Cannabidiol protects oligodendrocyte progenitor cells… These findings suggest that attenuation of the ER stress pathway is involved in the ‘oligoprotective’ effects of CBD during inflammation.”

http://www.ncbi.nlm.nih.gov/pubmed/22739983

Alternative targets within the endocannabinoid system for future treatment of gastrointestinal diseases

“Alternative targets within the endocannabinoid system for future treatment of gastrointestinal diseases… Many beneficial effects of herbal cannabinoids on gut motility and inflammation have been demonstrated, suggesting a vast potential for these compounds in the treatment of gastrointestinal disorders….endocannabinoid system’ (ECS), a cooperating network of molecules that regulate themetabolism of the body’s own and of exogenously administered cannabinoids. The ECS… offering many potential targets for pharmacological intervention. Of major therapeutic interest are nonpsychoactive cannabinoids that do not directly target cannabinoid receptors but still possess cannabinoid-like properties… promising alternative therapeutic tools to manipulate the ECS.”

http://www.ncbi.nlm.nih.gov/pubmed/21876860

Unraveling the complexities of cannabinoid receptor 2 (CB2) immune regulation in health and disease

CB2 is a potent regulator of immune responses making it a prime target for the treatment of inflammatory diseases.”

http://www.ncbi.nlm.nih.gov/pubmed/21626285

The endocannabinoid system in amyotrophic lateral sclerosis

“The endocannabinoid system in amyotrophic lateral sclerosis… Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative condition… there is significant evidence that several neurotoxic mechanisms including excitotoxicity, inflammation and oxidative stress, all contribute to disease pathogenesis… there is increasing evidence that cannabinoids and manipulation of the endocannabinoid system may have therapeutic value in ALS, in addition to other neurodegenerative conditions. Cannabinoids exert anti-glutamatergic and anti-inflammatory actions through activation of the CB(1) and CB(2) receptors… cannabinoid agents also exert anti-oxidant actions… the ability of cannabinoids to target multiple neurotoxic pathways in different cell populations increase their therapeutic potential in the treatment of ALS.”

http://www.ncbi.nlm.nih.gov/pubmed/18781981

The endocannabinoid system and neurogenesis in health and disease.

Consuming plant cannabinoids leads to neurogenesis (birth of neurons), thanks to the endocannabinoid system.

“The endocannabinoid system exerts an important neuromodulatory function in different brain areas and is also known to be involved in the regulation of neural cell fate.

Thus, CB(1) cannabinoid receptors are neuroprotective in different models of brain injury, and their expression is altered in various neurodegenerative diseases. Recent findings have demonstrated the presence of a functional endocannabinoid system in neural progenitor cells that participates in the regulation of cell proliferation and differentiation.

In this Research Update, the authors address the experimental evidence regarding the regulatory role of cannabinoids in neurogenesis and analyze them in the context of those pathological disorders in which cannabinoid function and altered neuronal or glial generation is most relevant, for example, stroke and multiple sclerosis.”