Targeting cannabinoid receptors in gastrointestinal cancers for therapeutic uses: current status and future perspectives

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“A number of studies have consistently shown that cannabinoids are able to prevent or reduce carcinogenesis in different animal models of colon cancer.

Cannabinoids, via CB1 and possibly CB2 receptors, suppress proliferation and migration and stimulate apoptosis in colorectal cancer cells.

Convincing scientific evidence suggests that cannabinoids, in addition to their well-known use in palliative care in oncology (e.g. improvement of appetite, attenuation of nausea associated to antitumoral medicines, alleviation of moderate neuropathic pain) can reduce, via antiproliferative and proapoptotic as well as by inhibiting angiogenesis, invasion and metastasis or by attenuating inflammation, the growth of cancer cells and hinder the development of experimental colon carcinogenesis in vivo.”

https://www.tandfonline.com/doi/full/10.1080/17474124.2017.1367663?src=recsys

INSIGHT ON THE IMPACT OF ENDOCANNABINOID SYSTEM IN CANCER: A REVIEW.

British Journal of Pharmacology banner

“In the last decades, the endocannabinoid system has attracted a great interest in medicine and cancer disease is probably one of its most promising therapeutic areas.

On the one hand, endocannabinoid system expression has been found altered in numerous types of tumours compared to healthy tissue, and this aberrant expression has been related to cancer prognosis and disease outcome, suggesting a role of this system in tumour growth and progression that depends on cancer type.

On the other hand, it has been reported that cannabinoids exert an anticancer activity by inhibiting the proliferation, migration and/or invasion of cancer cells; and also tumour angiogenesis.

The endocannabinoid system may be considered as a new therapeutic target, although further studies to fully establish the effect of cannabinoids on tumour progression remain necessary.”

https://www.ncbi.nlm.nih.gov/pubmed/29663308

Cannabidiol Induces Cytotoxicity and Cell Death via Apoptotic Pathway in Cancer Cell Lines

“In view of obtaining potential anticancer compounds, we studied the inhibitory activity and the cytotoxic effects of a candidate compound in cancer cells. The cytotoxic effects of cannabidiol (CBD) in vitro were evaluated in NIH3T3 fibroblasts, B16 melanoma cells, A549 lung cancer cells, MDA-MB-231 breast cancer cells, Lenca kidney cells and SNU-C4 colon cancer cells.
The inhibitory activity of CBD was increased in all cancer cells and showed especially strong increment in breast cancer cells. The cytotoxicity of CBD increased in a dose- and time-dependent manner with growth inhibition in all cancer cell lines.
Therefore these results suggest that CBD has a possibility of anticancer agents and anticancer effects against cancer cells by modulation of apoptotic pathway in the range of 5-80 μM concentration.”

Rimonabant Kills Colon Cancer Stem Cells without Inducing Toxicity in Normal Colon Organoids

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“Colorectal cancer (CRC), like other tumor types, is a highly heterogeneous disease. Within the tumor bulk, intra-tumoral heterogeneity is also ascribable to Cancer Stem Cells (CSCs) subpopulation, characterized by high chemoresistance and the unique ability to retain tumorigenic potential, thus associated to tumor recurrence. High dynamic plasticity of CSCs, makes the development of winning therapeutic strategies even more complex to completely eradicate tumor fuel.

Rimonabant, originally synthesized as antagonist/inverse agonist of Cannabinoid Receptor 1, is able to inactivate Wnt signaling, both in vitro and in vivo, in CRC models, through inhibition of p300-histone acetyltransferase activity. Since Wnt/β-Catenin pathway is the main player underlying CSCs dynamic, this finding candidates Rimonabant as potential modulator of cancer stemness, in CRC.

Overall, results from this work provided new insights on anti-tumor efficacy of Rimonabant, strongly suggesting that it could be a novel lead compound for CRC treatment.

 Anti-tumor action of cannabinoids in CRC was strongly supported by several authors.
The Endocannabinoid (EC) system role in the progression of CRC has been analyzed in vivo in the mouse model of azoxymethane-induced colon carcinogenesis, where cannabinoids-mediated reduction of precancerous lesions in the mouse colon was found.
In CRC cells, agonists and antagonists of both cannabinoid receptors, CB1 and CB2, showed anti-tumor action through induction of cell death with different mechanisms ranging from apoptosis to mitotic catastrophe”

Anti-Inflammatory Activity in Colon Models Is Derived from Δ9-Tetrahydrocannabinolic Acid That Interacts with Additional Compounds in Cannabis Extracts.

“Inflammatory bowel diseases (IBDs) include Crohn’s disease, and ulcerative colitis. Cannabis sativa preparations have beneficial effects for IBD patients. However, C. sativa extracts contain hundreds of compounds. Although there is much knowledge of the activity of different cannabinoids and their receptor agonists or antagonists, the cytotoxic and anti-inflammatory activity of whole C. sativa extracts has never been characterized in detail with in vitro and ex vivo colon models.

Material and Methods: The anti-inflammatory activity of C. sativa extracts was studied on three lines of epithelial cells and on colon tissue. C. sativa flowers were extracted with ethanol, enzyme-linked immunosorbent assay was used to determine the level of interleukin-8 in colon cells and tissue biopsies, chemical analysis was performed using high-performance liquid chromatography, mass spectrometry and nuclear magnetic resonance and gene expression was determined by quantitative real-time PCR.

Results: The anti-inflammatory activity of Cannabis extracts derives from D9-tetrahydrocannabinolic acid (THCA) present in fraction 7 (F7) of the extract. However, all fractions of C. sativa at a certain combination of concentrations have a significant increased cytotoxic activity. GPR55 receptor antagonist significantly reduces the anti-inflammatory activity of F7, whereas cannabinoid type 2 receptor antagonist significantly increases HCT116 cell proliferation. Also, cannabidiol (CBD) shows dose dependent cytotoxic activity, whereas anti-inflammatory activity was found only for the low concentration of CBD, and in a bell-shaped rather than dose-dependent manner. Activity of the extract and active fraction was verified on colon tissues taken from IBD patients, and was shown to suppress cyclooxygenase-2 (COX2) and metalloproteinase-9 (MMP9) gene expression in both cell culture and colon tissue.

Conclusions: It is suggested that the anti-inflammatory activity of Cannabis extracts on colon epithelial cells derives from a fraction of the extract that contains THCA, and is mediated, at least partially, via GPR55 receptor. The cytotoxic activity of the C. sativa extract was increased by combining all fractions at a certain combination of concentrations and was partially affected by CB2 receptor antagonist that increased cell proliferation. It is suggested that in a nonpsychoactive treatment for IBD, THCA should be used rather than CBD.”

Cannabidiol and Palmitoylethanolamide are anti-inflammatory in the acutely inflamed human colon.

Clinical Science “We sought to quantify the anti-inflammatory effects of two cannabinoid drugs: cannabidiol (CBD) and palmitoylethanolamide (PEA), in cultured cell lines and compared this effect with experimentally inflamed explant human colonic tissue.  These effects were explored in acutely and chronically inflamed colon, using inflammatory bowel disease and appendicitis explants.

Results:   IFNγ and TNFα treatment increased phosphoprotein and cytokine levels in Caco-2 cultures and colonic explants.  Phosphoprotein levels were significantly reduced by PEA or CBD in Caco-2 cultures and colonic explants.  CBD and PEA prevented increases in cytokine production in explant colon, but not in Caco-2 cells. CBD effects were blocked by the CB2antagonist AM630 and TRPV1 antagonist SB366791.  PEA effects were blocked by the PPARα antagonist GW6471.  PEA and CBD were anti-inflammatory in IBD and appendicitis explants.

Conclusion: PEA and CBD are anti-inflammatory in the human colon.  This effect is not seen in cultured epithelial cells. Appropriately sized clinical trials should assess their efficacy.”

https://www.ncbi.nlm.nih.gov/pubmed/28954820

http://www.clinsci.org/content/early/2017/09/26/CS20171288

Inhibition of Wnt/β-Catenin pathway and Histone acetyltransferase activity by Rimonabant: a therapeutic target for colon cancer.

 

“In a high percentage (≥85%) of both sporadic and familial adenomatous polyposis forms of colorectal cancer (CRC), the inactivation of the APC tumor suppressor gene initiates tumor formation and modulates the Wnt/β-Catenin transduction pathways involved in the control of cell proliferation, adhesion and metastasis.

Increasing evidence showed that the endocannabinoids control tumor growth and progression, both in vitro and in vivo.

We evaluated the effect of Rimonabant, a Cannabinoid Receptor 1 (CB1) inverse agonist, on the Wnt/β-Catenin pathway in HCT116 and SW48 cell lines carrying the genetic profile of metastatic CRC poorly responsive to chemotherapies.

Obtained data heavily supported the rationale for the use of cannabinoids in combined therapies for metastatic CRC harbouring activating mutations of β-Catenin.”

https://www.ncbi.nlm.nih.gov/pubmed/28916833

https://www.nature.com/articles/s41598-017-11688-x

G protein-coupled receptor GPR55 promotes colorectal cancer and has opposing effects to cannabinoid receptor 1.

International Journal of Cancer

“The putative cannabinoid receptor GPR55 has been shown to play a tumor-promoting role in various cancers, and is involved in many physiological and pathological processes of the gastrointestinal (GI) tract.

While the cannabinoid receptor 1 (CB1 ) has been reported to suppress intestinal tumor growth, the role of GPR55 in the development of GI cancers is unclear. We, therefore, aimed at elucidating the role of GPR55 in colorectal cancer (CRC), the third most common cancer worldwide.

Collectively, our data suggest that GPR55 and CB1 play differential roles in colon carcinogenesis where the former seems to act as oncogene and the latter as tumor suppressor.”

https://www.ncbi.nlm.nih.gov/pubmed/28875496

http://onlinelibrary.wiley.com/doi/10.1002/ijc.31030/abstract

A Review of the Therapeutic Antitumor Potential of Cannabinoids.

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“The aim of this review is to discuss cannabinoids from a preclinical and clinical oncological perspective and provide the audience with a concise, retrospective overview of the most significant findings concerning the potential use of cannabinoids in cancer treatment.

RESULTS:

Cannabis sativa is a plant rich in more than 100 types of cannabinoids. Besides exogenous plant cannabinoids, mammalian endocannabinoids and synthetic cannabinoid analogues have been identified. Cannabinoid receptors type 1 (CB1) and type 2 (CB2) have been isolated and characterized from mammalian cells. Through cannabinoid receptor and non-receptor signaling pathways, cannabinoids show specific cytotoxicity against tumor cells, while protecting healthy tissue from apoptosis. The dual antiproliferative and proapoptotic effects of cannabinoids and associated signaling pathways have been investigated on a large panel of cancer cell lines. Cannabinoids also display potent anticancer activity against tumor xenografts, including tumors that express high resistance to standard chemotherapeutics. Few studies have investigated the possible synergistic effects of cannabinoids with standard oncology therapies, and are based on the preclinically confirmed concept of “cannabinoid sensitizers.” Also, clinical trials aimed to confirm the antineoplastic activity of cannabinoids have only been evaluated on a small number of subjects, with no consensus conclusions regarding their effectiveness.

CONCLUSIONS:

A large number of cannabinoid compounds have been discovered, developed, and used to study the effects of cannabinoids on cancers in model systems. However, few clinical trials have been conducted on the use of cannabinoids in the treatment of cancers in humans. Further studies require extensive monitoring of the effects of cannabinoids alone or in combination with standard anticancer strategies. With such knowledge, cannabinoids could become a therapy of choice in contemporary oncology.”

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

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“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.”

https://www.ncbi.nlm.nih.gov/pubmed/28425013