Cannabinoids for Cancer Treatment: Progress and Promise

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Cancer Research: 68 (2)

“Cannabinoid refers to a group of chemicals naturally found in the marijuana plant Cannabis sativa L. and includes compounds that are either structurally or pharmacologically similar to Δ(9)-tetrahydrocannabinol or those that bind to the cannabinoid receptors. Although anticancer effects of cannabinoids were shown as early as 1975 in Lewis lung carcinoma, renewed interest was generated little after the discovery of the cannabinoid system and cloning of the specific cannabinoid receptors.

Cannabinoids are a class of pharmacologic compounds that offer potential applications as antitumor drugs, based on the ability of some members of this class to limit inflammation, cell proliferation, and cell survival. In particular, emerging evidence suggests that agonists of cannabinoid receptors expressed by tumor cells may offer a novel strategy to treat cancer. Here, we review recent work that raises interest in the development and exploration of potent, nontoxic, and nonhabit forming cannabinoids for cancer therapy.”

Full Text: http://cancerres.aacrjournals.org/content/68/2/339.long

Cannabinoid derivatives induce cell death in pancreatic MIA PaCa-2 cells via a receptor-independent mechanism.

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“Cannabinoids (CBs) are implicated in the control of cell survival in different types of tumors, but little is known about the role of CB system in pancreatic cancer. Herein, we investigated the in vitro antitumor activity of CBs and the potential role of their receptors in human pancreatic cancer cells MIA PaCa-2…

These findings exclude the involvement of CB receptors in the regulation of MIA PaCa-2 cell growth and put AM251 forward as a candidate for the development of novel compounds worthy to be tested in this type of neoplasia.”

http://www.ncbi.nlm.nih.gov/pubmed/16500647

Cannabinoids Halt Pancreatic Cancer, Breast Cancer Growth, Studies Say

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“Compounds in cannabis inhibit cancer cell growth in human breast cancer cell lines and in pancreatic tumor cell lines, according to a pair of preclinical trials published in the July issue of the journal of the American Association for Cancer Research.

In one trial, investigators at Complutense University in Spain and the Institut National de la Sante et de la Recherche Medicale (INSERM) in France assessed the anti-cancer activity of cannabinoids in pancreatic cancer cell lines and in animals. Cannabinoid administration selectively increased apoptosis (programmed cell death) in pancreatic tumor cells while ignoring healthy cells, researchers found. In addition, “cannabinoid treatment inhibited the spreading of pancreatic tumor cells … and reduced the growth of tumor cells” in animals.

“These findings may contribute to … a new therapeutic approach for the treatment of pancreatic cancer,” authors concluded.

In the second trial, investigators at Spain’s Complutense University reported that THC administration “reduces human breast cancer cell proliferation [in vitro] by blocking the progression of the cell cycle and by inducing apoptosis.” Authors concluded that their findings “may set the bases for a cannabinoid therapy for the management of breast cancer.”

Previous preclinical data published in May in the Journal of Pharmacological and Experimental Therapeutics reported that non-psychoactive cannabinoids, particularly cannabidiol (CBD), dramatically halt the spread of breast cancer cells and recommended their use in cancer therapy.

Separate trials have also shown cannabinoids to reduce the size and halt the spread of glioma (brain tumor) cells in animals and humans in a dose dependent manner. Additional preclinical studies have demonstrated cannabinoids to inhibit cancer cell growth and selectively trigger malignant cell death in skin cancer cells, leukemic cells, lung cancer cells, and prostate carcinoma cells, among other cancerous cell lines.”

http://norml.org/news/2006/07/06/cannabinoids-halt-pancreatic-cancer-breast-cancer-growth-studies-say

The role of the pancreatic endocannabinoid system in glucose metabolism.

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“The endogenous cannabinoid system participates in the regulation of energy homeostasis, and this fact led to the identification of a new group of therapeutic agents for complicated obesity and diabetes. Cannabinoid receptor antagonists are now realities in clinical practice. The use of such antagonists for reducing body weight gain, lowering cholesterol and improving glucose homeostasis is based on the ability of the endocannabinoids to coordinately regulate energy homeostasis by interacting with central and peripheral targets, including adipose tissue, muscle, liver and endocrine pancreas. In this review we will analyse the presence of this system in the main cell types of the islets of Langerhans, as well as the physiological relevance of the endocannabinoids and parent acylethanolamides in hormone secretion and glucose homeostasis. We will also analyse the impact that these findings may have in clinical practice and the potential outcome of new therapeutic strategies for modulating glucose homeostasis and insulin/glucagon secretion.”

http://www.ncbi.nlm.nih.gov/pubmed/19285263

Presence of functional cannabinoid receptors in human endocrine pancreas.

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“We examined the presence of functional cannabinoid receptors 1 and 2 (CB1, CB2) in isolated human islets, phenotyped the cells producing cannabinoid receptors and analysed the actions of selective cannabinoid receptor agonists on insulin, glucagon and somatostatin secretion in vitro. We also described the localisation on islet cells of: (1) the endocannabinoid-producing enzymes N-acyl-phosphatidyl ethanolamine-hydrolysing phospholipase D and diacylglycerol lipase; and (2) the endocannabinoid-degrading enzymes fatty acid amidohydrolase and monoacyl glycerol lipase.

RESULTS:

Human islets of Langerhans expressed CB1 and CB2 (also known as CNR1 and CNR2) mRNA and CB1 and CB2 proteins, and also the machinery involved in synthesis and degradation of 2-AG (the most abundant endocannabinoid, levels of which were modulated by glucose). Immunofluorescence revealed that CB1 was densely located in glucagon-secreting alpha cells and less so in insulin-secreting beta cells. CB2 was densely present in somatostatin-secreting delta cells, but absent in alpha and beta cells. In vitro experiments revealed that CB1 stimulation enhanced insulin and glucagon secretion, while CB2 agonism lowered glucose-dependent insulin secretion, showing these cannabinoid receptors to be functional.

CONCLUSIONS/INTERPRETATION:

Together, these results suggest a role for endogenous endocannabinoid signalling in regulation of endocrine secretion in the human pancreas.”

http://www.ncbi.nlm.nih.gov/pubmed/18092149

Gemcitabine/cannabinoid combination triggers autophagy in pancreatic cancer cells through a ROS-mediated mechanism

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“Pancreatic adenocarcinoma is one of the most aggressive and devastating human malignancies with a death-to-incidence ratio of 0.99. Although it represents only 2–3% of all cancers, pancreatic adenocarcinoma is the fourth cause of death by tumors…

In recent years, there has been increasing interest in cannabinoids as therapeutic drugs for their antineoplastic, anticachectic, and analgesic potential. Growth inhibitory activities of cannabinoids have been demonstrated for various malignancies, including brain, breast, prostate, colorectal, skin and, recently, pancreatic cancer…

In the present study, we have demonstrated that the combination between the standard chemotherapy agent GEM and cannabinoids synergistically inhibited pancreatic adenocarcinoma cell growth by a ROS-dependent autophagic cell death.

These findings support a key role of the ROS-dependent activation of an autophagic program in the synergistic growth inhibition induced by GEM/cannabinoid combination in human pancreatic cancer cells.

GEM and cannabinoids strongly inhibited growth of human pancreatic adenocarcinoma cells in vivo.”

Read more: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3122066/

US Investigators Praise Cannabinoids As Chemo Treatment

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“Cannabinoids inhibit cancer cell proliferation and should be clinically tested as chemotherapeutic agents, according to a review published in the January issue of the journal Cancer Research.

Investigators at the University of Wisconsin School of Medicine and Public Health reported that the administration of cannabinoids halts the spread of a wide range of cancers, including brain cancer, prostate cancer, breast cancer, lung cancer, skin cancer, pancreatic cancer, and lymphoma.

Researchers suggested that cannabinoids may offer significant advantages over standard chemotherapy treatments because the compounds are both non-toxic and can uniquely target malignant cells while ignoring healthy ones.

“Cannabinoids … offer potential applications as anti-tumor drugs, based on the ability of some members of this class to limit inflammation, cell proliferation, and cell survival,” authors concluded. “[T]here is overwhelming evidence to suggest that cannabinoids can be explored as chemotherapeutic agents for the treatment of cancer.””

Read more: http://norml.org/news/2008/01/31/us-investigators-praise-cannabinoids-as-chemo-treatment

Cannabinoids Induce Apoptosis of Pancreatic Tumor Cells

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 “Pancreatic adenocarcinomas are among the most malignant forms of cancer and, therefore, it is of especial interest to set new strategies aimed at improving the prognostic of this deadly disease. The present study was undertaken to investigate the action of cannabinoids, a new family of potential antitumoral agents, in pancreatic cancer. We show that cannabinoid receptors are expressed in human pancreatic tumor cell lines …

 Cannabinoids… reduced the growth of tumor cells in two animal models of pancreatic cancer. In addition, cannabinoid treatment inhibited the spreading of pancreatic tumor cells. Moreover, cannabinoid administration selectively increased apoptosis and TRB3 expression in pancreatic tumor cells but not in normal tissue… results presented here show that cannabinoids lead to apoptosis of pancreatic tumor cells via a CB2 receptor and de novo synthesized ceramide-dependent up-regulation of p8 and the endoplasmic reticulum stress–related genes ATF-4 and TRB3.

 These findings may contribute to set the basis for a new therapeutic approach for the treatment of pancreatic cancer.

In conclusion, results presented here show that cannabinoids exert a remarkable antitumoral effect on pancreatic cancer cells in vitro and in vivo…

 These findings may help to set the basis for a new therapeutic approach for the treatment of this deadly disease.”

http://www.420magazine.com/forums/pancreatic-cancer/145013-cannabinoids-induce-apoptosis-pancreatic-tumor-cells.html

 

“Cannabinoids Induce Apoptosis of Pancreatic Tumor Cells via Endoplasmic Reticulum Stress–Related Genes“

 

Full text: http://cancerres.aacrjournals.org/content/66/13/6748.long

Regulation, function, and dysregulation of endocannabinoids in models of adipose and beta-pancreatic cells and in obesity and hyperglycemia.

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“Cannabinoid CB(1) receptor blockade decreases weight and hyperinsulinemia in obese animals and humans in a way greatly independent from food intake.

The objective of this study was to investigate the regulation and function of the endocannabinoid system in adipocytes and pancreatic beta-cells.

Endocannabinoid enzyme and adipocyte protein expression, and endocannabinoid and insulin levels were measured.

RESULTS:

Endocannabinoids are present in adipocytes with levels peaking before differentiation, and in RIN-m5F beta-cells, where they are under the negative control of insulin. Chronic treatment of adipocytes with insulin is accompanied by permanently elevated endocannabinoid signaling, whereas culturing of RIN-m5F beta-cells in high glucose transforms insulin down-regulation of endocannabinoid levels into up-regulation. Epididymal fat and pancreas from mice with diet-induced obesity contain higher endocannabinoid levels than lean mice. Patients with obesity or hyperglycemia caused by type 2 diabetes exhibit higher concentrations of endocannabinoids in visceral fat or serum, respectively, than the corresponding controls. CB(1) receptor stimulation increases lipid droplets and decreases adiponectin expression in adipocytes, and it increases intracellular calcium and insulin release in RIN-m5F beta-cells kept in high glucose.

CONCLUSIONS:

Peripheral endocannabinoid overactivity might explain why CB(1) blockers cause weight-loss independent reduction of lipogenesis, of hypoadiponectinemia, and of hyperinsulinemia in obese animals and humans.”

http://jcem.endojournals.org/content/91/8/3171.long

Mechanisms for the coupling of cannabinoid receptors to intracellular calcium mobilization in rat insulinoma beta-cells.

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“In RIN m5F rat insulinoma beta-cells, agonists at cannabinoid CB(1) receptors modulate insulin release. Here we investigated in these cells the effect of the activation of cannabinoid CB(1) and CB(2) receptors on intracellular Ca(2+) ([Ca(2+)](i)). The CB(1) agonist arachidonoyl-chloro-ethanolamide (ACEA), and the CB(2) agonist JWH133, elevated [Ca(2+)](i) in a way sensitive to the inhibitor of phosphoinositide-specific phospholipase C (PI-PLC), U73122 (but not to pertussis toxin and forskolin), and independently from extracellular Ca(2+). PI-PLC-dependent Ca(2+) mobilization by ACEA was entirely accounted for by activation of inositol-1,3,4-phosphate (IP(3)) receptors on the endoplasmic reticulum (ER), whereas the effect of JWH133 was not sensitive to all tested inhibitors of IP(3) and ryanodine receptors. ACEA, but not JWH133, significantly inhibited the effect on [Ca(2+)](i) of bombesin, which acts via G(q/11)- and PI-PLC-coupled receptors in insulinoma cells. The endogenous CB(1) agonists, anandamide and N-arachidonoyldopamine, which also activate transient receptor potential vanilloid type 1 (TRPV1) receptors expressed in RIN m5F cells, elevated [Ca(2+)](i) in the presence of extracellular Ca(2+) in a way sensitive to both CB(1) and TRPV1 antagonists. These results suggest that, in RIN m5F cells, CB(1) receptors are coupled to PI-PLC-mediated mobilization of [Ca(2+)](i) and might inhibit bombesin signaling.”

http://www.ncbi.nlm.nih.gov/pubmed/17585904