Future Aspects for Cannabinoids in Breast Cancer Therapy.

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“Cannabinoids (CBs) from Cannabis sativa provide relief for tumor-associated symptoms (including nausea, anorexia, and neuropathic pain) in the palliative treatment of cancer patients.

Additionally, they may decelerate tumor progression in breast cancer patients.

Indeed, the psychoactive delta-9-tetrahydrocannabinol (THC), non-psychoactive cannabidiol (CBD) and other CBs inhibited disease progression in breast cancer models.

The effects of CBs on signaling pathways in cancer cells are conferred via G-protein coupled CB-receptors (CB-Rs), CB1-R and CB2-R, but also via other receptors, and in a receptor-independent way.

THC is a partial agonist for CB1-R and CB2-R; CBD is an inverse agonist for both.

In breast cancer, CB1-R expression is moderate, but CB2-R expression is high, which is related to tumor aggressiveness. CBs block cell cycle progression and cell growth and induce cancer cell apoptosis by inhibiting constitutive active pro-oncogenic signaling pathways, such as the extracellular-signal-regulated kinase pathway.

They reduce angiogenesis and tumor metastasis in animal breast cancer models. CBs are not only active against estrogen receptor-positive, but also against estrogen-resistant breast cancer cells. In human epidermal growth factor receptor 2-positive and triple-negative breast cancer cells, blocking protein kinase B- and cyclooxygenase-2 signaling via CB2-R prevents tumor progression and metastasis.

Furthermore, selective estrogen receptor modulators (SERMs), including tamoxifen, bind to CB-Rs; this process may contribute to the growth inhibitory effect of SERMs in cancer cells lacking the estrogen receptor.

In summary, CBs are already administered to breast cancer patients at advanced stages of the disease, but they might also be effective at earlier stages to decelerate tumor progression.”

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WIN55,212-2 induces caspase-independent apoptosis on human glioblastoma cells by regulating HSP70, p53 and Cathepsin D.

Toxicology in Vitro

“Despite the standard approaches to treat the highly aggressive and invasive glioblastoma (GBM), it remains incurable.

In this sense, cannabinoids highlight as a promising tool, because this tumor overexpresses CB1 and/or CB2 receptors and being, therefore, can be susceptible to cannabinoids treatment.

Thus, this work investigated the action of the cannabinoid agonist WIN55-212-2 on GBM cell lines and non-malignant cell lines, in vitro and in vivo. WIN was selectively cytotoxic to GBM cells. These presented blebbing and nuclear alterations in addition to cell shrinkage and chromatin condensation. WIN also significantly inhibited the migration of GAMG and U251 cells.

Finally, the data also showed that the antitumor effects of WIN are exerted, at least to some extent, by the expression of p53 and increased cathepsin D in addition to the decreased expression of HSP70.This data can indicate caspase-independent cell death mechanism. In addition, WIN decreased tumoral perimeter as well as caused a reduction the blood vessels in this area, without causing lysis, hemorrhage or blood clotting.

So, the findings herein presented reinforce the usefulness of cannabinoids as a candidate for further evaluation in treatment in glioblastoma treatment.”

https://www.ncbi.nlm.nih.gov/pubmed/30776504

https://www.sciencedirect.com/science/article/pii/S0887233318307537?via%3Dihub

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On the influence of cannabinoids on cell morphology and motility of glioblastoma cells.

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“The mechanisms behind the anti-tumoral effects of cannabinoids by impacting the migratory activity of tumor cells are only partially understood. Previous studies demonstrated that cannabinoids altered the organization of the actin cytoskeleton in various cell types.

As actin is one of the main contributors to cell motility and is postulated to be linked to tumor invasion, we tested the following hypothesizes: 1) Can cannabinoids alter cell motility in a cannabinoid receptor dependent manner? 2) Are these alterations associated with reorganizations in the actin cytoskeleton? 3) If so, what are the underlying molecular mechanisms?

Three different glioblastoma cell lines were treated with specific cannabinoid receptor 1 and 2 agonists and antagonists. Afterwards, we measured changes in cell motility using live cell imaging and alterations of the actin structure in fixed cells. Additionally, the protein amount of phosphorylated p44/42 mitogen-activated protein kinase (MAPK), focal adhesion kinases (FAK) and phosphorylated FAK (pFAK) over time were measured.

Cannabinoids induced changes in cell motility, morphology and actin organization in a receptor and cell line dependent manner. No significant changes were observed in the analyzed signaling molecules. Cannabinoids can principally induce changes in the actin cytoskeleton and motility of glioblastoma cell lines. Additionally, single cell motility of glioblastoma is independent of their morphology. Furthermore, the observed effects seem to be independent of p44/42 MAPK and pFAK pathways.”

https://www.ncbi.nlm.nih.gov/pubmed/30753211

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0212037

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Therapeutic targeting of HER2-CB2R heteromers in HER2-positive breast cancer.

 Proceedings of the National Academy of Sciences: 116 (6)

“Although human epidermal growth factor receptor 2 (HER2)-targeted therapies have dramatically improved the clinical outcome of HER2-positive breast cancer patients, innate and acquired resistance remains an important clinical challenge. New therapeutic approaches and diagnostic tools for identification, stratification, and treatment of patients at higher risk of resistance and recurrence are therefore warranted.

Here, we unveil a mechanism controlling the oncogenic activity of HER2: heteromerization with the cannabinoid receptor CB2R. We show that HER2 physically interacts with CB2R in breast cancer cells, and that the expression of these heteromers correlates with poor patient prognosis.

The cannabinoid Δ9-tetrahydrocannabinol (THC) disrupts HER2-CB2R complexes by selectively binding to CB2R, which leads to (i) the inactivation of HER2 through disruption of HER2-HER2 homodimers, and (ii) the subsequent degradation of HER2 by the proteasome via the E3 ligase c-CBL. This in turn triggers antitumor responses in vitro and in vivo. Selective targeting of CB2R transmembrane region 5 mimicked THC effects.

Together, these findings define HER2-CB2R heteromers as new potential targets for antitumor therapies and biomarkers with prognostic value in HER2-positive breast cancer.”

https://www.ncbi.nlm.nih.gov/pubmed/30733293

https://www.pnas.org/content/early/2019/02/06/1815034116

“Pharmacological activation of cannabinoid receptors elicits antitumoral responses in different cancer models. Our findings reveal an unprecedented role of CB2 as a pivotal regulator of HER2 pro-oncogenic signaling in breast cancer” http://www.ncbi.nlm.nih.gov/pubmed/25855725
“Extensive preclinical research has demonstrated that cannabinoids, the active ingredients of Cannabis sativa, trigger antitumor responses in different models of cancer. Together, our results suggest that standardized cannabis drug preparations, rather than pure cannabinoids, could be considered as part of the therapeutic armamentarium to manage breast cancer.” https://www.ncbi.nlm.nih.gov/pubmed/29940172
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Potential Use of Cannabinoids for the Treatment of Pancreatic Cancer.

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Cannabinoid extracts may have anticancer properties, which can improve cancer treatment outcomes.

The aim of this review is to determine the potentially utility of cannabinoids in the treatment of pancreatic cancer.

Results: Cannabinol receptors have been identified in pancreatic cancer with several studies showing in vitroantiproliferative and proapoptotic effects. The main active substances found in cannabis plants are cannabidiol (CBD) and tetrahydrocannabinol (THC). There effects are predominately mediated through, but not limited to cannabinoid receptor-1, cannabinoid receptor-2, and G-protein-coupled receptor 55 pathways. In vitro studies consistently demonstrated tumor growth-inhibiting effects with CBD, THC, and synthetic derivatives. Synergistic treatment effects have been shown in two studies with the combination of CBD/synthetic cannabinoid receptor ligands and chemotherapy in xenograft and genetically modified spontaneous pancreatic cancer models. There are, however, no clinical studies to date showing treatment benefits in patients with pancreatic cancer.

Conclusions: Cannabinoids may be an effective adjunct for the treatment of pancreatic cancer. Data on the anticancer effectiveness of various cannabinoid formulations, treatment dosing, precise mode of action, and clinical studies are lacking.”

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Cannabidiol-induced apoptosis is mediated by activation of Noxa in human colorectal cancer cells.

Cancer Letters

“Cannabidiol (CBD), one of the compounds present in the marijuana plant, has anti-tumor properties, but its mechanism is not well known.

This study aimed to evaluate the apoptotic action of CBD in colorectal cancer (CRC) cells, and focused on its effects on the novel pro-apoptotic Noxa-reactive oxygen species (ROS) signaling pathway.

CBD experiments were performed using the CRC cell lines HCT116 and DLD-1. CBD induced apoptosis by regulating many pro- and anti-apoptotic proteins, of which Noxa showed significantly higher expression. To understand the relationship between Noxa and CBD-induced apoptosis, Noxa levels were downregulated using siRNA, and the expression of apoptosis markers decreased.

After ROS production was blocked, the level of Noxa also decreased, suggesting that ROS is involved in the regulation of Noxa, which along with ROS is a well-known pro-apoptotic signaling agents. As a result, CBD induced apoptosis in a Noxa-and-ROS-dependent manner.

Taken together, the results obtained in this study re-demonstrated the effects of CBD treatment in vivo, thus confirming its role as a novel, reliable anticancer drug.”

https://www.ncbi.nlm.nih.gov/pubmed/30660647

“Our results using cells, mice, and patient-derived cells strongly suggest, for the first time, that that CBD can cause Noxa-induced cell death. These results suggest that that CBD has important implications for the potential treatment of human CRC.”

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Naturally occurring compounds as pancreatic cancer therapeutics.

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“Naturally occurring small molecule compounds have long been in the spotlight of pancreatic cancer research as potential therapeutics to prevent cancer progression and sensitize chemoresistant tumors. The hope is that terminal pancreatic cancer patients receiving aggressive chemotherapy can benefit from an increase in treatment efficacy without adding further toxicity by way of utilizing natural compounds. While preclinical studies on a number of natural compounds, such as resveratrol, curcumin, rapalogs and cannabinoids, show promising preclinical results, little has translated into clinical practice, though a number of other compounds hold clinical potential. Nevertheless, recent advances in compound formulation may increase the clinical utility of these compounds.”

https://www.ncbi.nlm.nih.gov/pubmed/30459936

“The combination of natural products and standard of care chemotherapy has the potential to increase quality of life and lifespan in pancreatic cancer patients, even though a number of hurdles need to be overcome for routine clinical use.”  http://www.oncotarget.com/index.php?journal=oncotarget&page=article&op=view&path[]=26234&path[]=81769

“Cannabinoids Induce Apoptosis of Pancreatic Tumor Cells via Endoplasmic Reticulum Stress–Related Genes. In conclusion, results presented here show that cannabinoids exert a remarkable antitumoral effect on pancreatic cancer cells in vitro and in vivo due to their ability to selectively induce apoptosis of these cells via activation of the p8-ATF-4-TRB3 proapoptotic pathway.”  http://cancerres.aacrjournals.org/content/66/13/6748

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The endocannabinoid signaling system in cancer

Image result for trends in pharmacological sciences“Changes in lipid metabolism are intimately related to cancer. Several classes of bioactive lipids play roles in the regulation of signaling pathways involved in neoplastic transformation and tumor growth and progression.

The endocannabinoid system, comprising lipid-derived endocannabinoids, their G-protein-coupled receptors (GPCRs), and the enzymes for their metabolism, is emerging as a promising therapeutic target in cancer.

This report highlights the main signaling pathways for the antitumor effects of the endocannabinoid system in cancer and its basic role in cancer pathogenesis, and discusses the alternative view of cannabinoid receptors as tumor promoters.

We focus on new players in the antitumor action of the endocannabinoid system and on emerging crosstalk among cannabinoid receptors and other membrane or nuclear receptors involved in cancer. We also discuss the enzyme MAGL, a key player in endocannabinoid metabolism that was recently recognized as a marker of tumor lipogenic phenotype.”

https://www.cell.com/trends/pharmacological-sciences/fulltext/S0165-6147(13)00044-8?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0165614713000448%3Fshowall%3Dtrue

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Light-activatable cannabinoid prodrug for combined and target-specific photodynamic and cannabinoid therapy.

“Cannabinoids are emerging as promising antitumor drugs. However, complete tumor eradication solely by cannabinoid therapy remains challenging. In this study, we developed a far-red light activatable cannabinoid prodrug, which allows for tumor-specific and combinatory cannabinoid and photodynamic therapy. This prodrug consists of a phthalocyanine photosensitizer (PS), reactive oxygen species (ROS)-sensitive linker, and cannabinoid. It targets the type-2 cannabinoid receptor (CB2R) overexpressed in various types of cancers. Upon the 690-nm light irradiation, the PS produces cytotoxic ROS, which simultaneously cleaves the ROS-sensitive linker and subsequently releases the cannabinoid drug. We found that this unique multifunctional prodrug design offered dramatically improved therapeutic efficacy, and therefore provided a new strategy for targeted, controlled, and effective antitumor cannabinoid therapy.”

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Report of Objective Clinical Responses of Cancer Patients to Pharmaceutical-grade Synthetic Cannabidiol.

“Cannabinoids are widely used in the management of pain, nausea and cachexia in cancer patients. However, there has been no objective clinical evidence of any anticancer activity yet.

The aim of this study was to assess the effects of pharmaceutical-grade synthetic cannabidiol on a range of cancer patients.

RESULTS:

Clinical responses were seen in 92% of the 119 cases with solid tumours including a reduction in circulating tumour cells in many cases and in other cases, a reduction in tumour size, as shown by repeat scans. No side-effects of any kind were observed when using pharmaceutical grade synthetic cannabidiol.

CONCLUSION:

Pharmaceutical-grade synthetic cannabidiol is a candidate for treating breast cancer and glioma patients.”

https://www.ncbi.nlm.nih.gov/pubmed/30275207

http://ar.iiarjournals.org/content/38/10/5831

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