“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.”
“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.”
“Cannabinoid receptor type 2 (CB2) is the primary receptor pathway mediating the immunologic consequences of cannabinoids.
We recently reported that human peripheral blood B cells express CB2 on both the extracellular membrane and at intracellular sites, where-as monocytes and T cells only express intracellular CB2. To better understand the pattern of CB2 expression by human B cells, we examined CD20+ B cells from three tissue sources.
Both surface and intracellular expression were present and uniform in cord blood B cells, where all cells exhibited a naïve mature phenotype (IgD+/CD38Dim). While naïve mature and quiescent memory B cells (IgD–/CD38–) from tonsils and peripheral blood exhibited a similar pattern, tonsillar activated B cells (IgD–/CD38+) expressed little to no surface CB2.
We hypothesized that regulation of the surface CB2 receptor may occur during B cell activation. Consistent with this, a B cell lymphoma cell line known to exhibit an activated phenotype (SUDHL-4) was found to lack cell surface CB2 but express intracellular CB2.
Furthermore, in vitro activation of human cord blood resulted in a down-regulation of surface CB2 on those B cells acquiring the activated phenotype but not on those retaining IgD expression. Using a CB2 expressing cell line (293 T/CB2-GFP), confocal microscopy confirmed the presence of both cell surface expression and multifocal intracellular expression, the latter of which co-localized with endoplasmic reticulum but not with mitochondria, lysosomes, or nucleus.
Our findings suggest a dynamic multi-compartment expression pattern for CB2 in B cells that is specifically modulated during the course of B cell activation.”
“The irritant properties of all smoke will naturally tend to promote a pro-inflammatory immune response with the corresponding production of potentially carcinogenic free radicals. However, cannabis promotes immune deviation to an anti-inflammatory Th2 response via immune-system specific CB2 receptors. Thus, the natural pharmacological properties of marijuana’s cannabinoids, that are not present in tobacco smoke, would minimize potential irritant initiated carcinogenesis. In contrast, the pharmacological activities of tobacco smoke would tend to amplify its carcinogenic potential by inhibiting the death of genetically damaged cells. Together these observations support the epidemiological study of the Kaiser Foundation that did not find cannabis smoking to be associated with cancer incidence. Additionally, the demonstrated cancer killing activities of cannabinoids has been ignored. Cannabinoids have been shown to kill some leukemia and lymphoma, breast and prostate, pheochromocytoma, glioma and skin cancer cells in cell culture and in animals.” http://www.bmj.com/rapid-response/2011/10/29/science-based-evaluation-cannabis-and-cancer
“Ceramide accumulation is a widely described event in cancers after various treatments.
Ceramide levels are elevated in Mantle Cell Lymphoma (MCL) cells following treatment with cannabinoids.
In previous publications we and others observed that induction of ceramide accumulation by cannabinoids leads to apoptosis in MCL, glioma and pancreatic cancer.
Here, we investigated the pathways of ceramide accumulation in the MCL cell line Rec-1 using the stable endocannabinoid analogue R(+)-methanandamide (R-MA).
Our findings suggest that R-MA induces cell death in MCL via CB1-mediated upregulation of the de novo ceramide synthesis pathway.
This is the first study showing that the cytotoxic effect of a cannabinoid can be enhanced by modulation of ceramide metabolism.
The results suggest that interference with ceramide conversion may provide a tool to enhance the targeted cell death-promoting effects of cannabinoids in MCL and other malignant lymphomas overexpressing the CB1 receptor.
Cannabinoids have been suggested as a new non-toxic therapeutic option for cancer treatment.”
“Mantle cell lymphoma (MCL) is a non-curable B cell lymphoma that in several independent studies have been shown to express higher levels of CB1 and CB2 than non-malignant B cells.
The endocannabinoid system is dysregulated in many types of cancer and is involved in the regulation of survival and proliferation of cancer cells and cancer stem cells, in cancer metabolism, as well as in pro-metastatic events such as angiogenesis, migration and invasion.
Previous in vitro studies of MCL cell lines and primary ex vivo isolated tumor cells have demonstrated that high concentrations of cannabinoid receptor ligands induced proliferation arrest and programmed cell death.
All together, the data suggest that perturbations in the endocannabinoid system participate in the regulation of multi-functional cell responses regarding proliferation, migration and cell death control.
Therefore, it can be concluded that further studies on pharmacological modulation of endocannabinoid accumulation and/or signaling offers an interesting option for novel anti-lymphoma therapy.”
“We have recently shown that cannabinoids induce growth inhibition and apoptosis in mantle cell lymphoma (MCL), a malignant B-cell lymphoma that expresses high levels of cannabinoid receptor types 1 and 2 (CB(1) and CB(2)).
In the current study, the role of each receptor and the signal transduction triggered by receptor ligation were investigated.
The present data suggest that targeting CB(1)/CB(2) may have therapeutic potential for the treatment of mantle cell lymphoma.”
“In conclusion, we have found that cannabinoid receptor ligands induce decreased viability, growth suppression and cell death by apoptosis in MCL cells, which express high levels of the CB1 receptor and moderate levels of CB2.
“The initiating oncogenic event in mantle cell lymphoma (MCL) is the translocation of cyclin D1, t(11;14)(q13;q32). However, other genetic aberrations are necessary for an overt lymphoma to arise. Like other B cell lymphomas, MCL at some points during the oncogenesis is dependent on interactions with other cells and factors in the microenvironment.
The G protein coupled receptors cannabinoid receptors 1 and 2 (CB1 and CB2) are expressed at low levels on non-malignant lymphocytes and at higher levels in MCL and other lymphoma subtypes.
In this review we give an overview of what is known on the role of the cannabinoid receptors and their ligands in lymphoma as compared to non-malignant T and B lymphocytes.
In MCL cannabinoids mainly reduce cell proliferation and induce cell death.
Importantly, our recent findings demonstrate that cannabinoids may induce either apoptosis or another type of programmed cell death, cytoplasmic vacuolation/paraptosis in MCL.”