Pathways mediating the effects of cannabidiol on the reduction of breast cancer cell proliferation, invasion, and metastasis

Abstract

Invasion and metastasis of aggressive breast cancer cells are the final and fatal steps during cancer progression. Clinically, there are still limited therapeutic interventions for aggressive and metastatic breast cancers available. Therefore, effective, targeted, and non-toxic therapies are urgently required. Id-1, an inhibitor of basic helix-loop-helix transcription factors, has recently been shown to be a key regulator of the metastatic potential of breast and additional cancers. We previously reported that cannabidiol (CBD), a cannabinoid with a low toxicity pro-file, down-regulated Id-1 gene expression in aggressive human breast cancer cells in culture. Using cell proliferation and invasion assays, cell flow cytometry to examine cell cycle and the formation of reactive oxygen species, and Western analysis, we determined pathways leading to the down-regulation of Id-1 expression by CBD and consequently to the inhibition of the proliferative and invasive phenotype of human breast cancer cells. Then, using the mouse 4T1 mammary tumor cell line and the ranksum test, two different syngeneic models of tumor metastasis to the lungs were chosen to determine whether treatment with CBD would reduce metastasis in vivo. We show that CBD inhibits human breast cancer cell proliferation and invasion through differential modulation of the extracellular signal-regulated kinase (ERK) and reactive oxygen species (ROS) pathways, and that both pathways lead to down-regulation of Id-1 expression. Moreover, we demonstrate that CBD up-regulates the pro-differentiation factor, Id-2. Using immune competent mice, we then show that treatment with CBD significantly reduces primary tumor mass as well as the size and number of lung metastatic foci in two models of metastasis. Our data demonstrate the efficacy of CBD in pre-clinical models of breast cancer. The results have the potential to lead to the development of novel non-toxic compounds for the treatment of breast cancer metastasis, and the information gained from these experiments broaden our knowledge of both Id-1 and cannabinoid biology as it pertains to cancer progression.

From Phytocannabinoids to Cannabinoid Receptors and Endocannabinoids: Pleiotropic Physiological and Pathological Roles Through Complex Pharmacology

“…In human prostate carcinoma cells, CBD induces apoptosis and expression of PUMA and CHOP, two markers of intrinsic apoptotic pathways (194). The production of ROS is at least in part responsible for the antitumor activity of the phytocannabinoid both in vitro (194,478,539,547) and in vivo (800).…”

“…It dampens nitric oxide (NO) production in animal models of acute and chronic inflammation (24,152,162,247,267,600,654,758), the expression of inflammatory cytokines and transcription factors [interleukin (IL)-1␤, IL-2, IL-6, IL-8, tumor necrosis factor (TNF)-␣, interferon (IFN)-␥, CCL3, CCL4, NF-B] (39, 419), and reactive oxygen species (ROS) production (320, 767). However, in many types of cancer cells, CBD is capable of generating ROS, thereby inducing cytotoxicity or apoptosis and autophagy (478,540,543,547,552,610,862). CBD also improves mithochondrial function and enhances mithochondrial biogenesis in vivo under pathological conditions (327).…”

Combined Antiproliferative Effects of the Aminoalkylindole WIN55,212-2 and Radiation in Breast Cancer Cells

“…A preponderance of studies in the literature investigating the effects of cannabinoids on cancer cells have been performed under low-serum conditions (Carracedo et al, 2006;Salazar et al, 2009;McAllister et al, 2011;Wasik et al, 2011). In contrast, the experiments presented in the present work were performed using media containing 10% serum.…”

“…The results of preclinical trials suggest that these agents may prove to be of use for patients experiencing nausea and vomiting due to radiation therapy (Darmani et al, 2007). Cannabinoids are also known to suppress growth or promote cell death in a variety of cancer cell lines, including glioma, pancreatic, melanoma, lymphoma, lung, and breast (Carracedo et al, 2006;Qamri et al, 2009;Salazar et al, 2009;McAllister et al, 2011;Preet et al, 2011;Scuderi et al, 2011;Wasik et al, 2011). Given that cannabinoid-based drugs are used for suppression of nausea and for appetite stimulation in patients with cancer, as well as their potential utility as adjunctive treatments along with conventional therapies such as radiation, the present studies were initiated to determine whether cannabinoids might augment the antiproliferative actions of radiation in breast tumor cells.…”

The Pharmacological Basis of Cannabis Therapy for Epilepsy

“…Owing to its lack of psychoactive properties and the low rate at which a tolerance develops, CBD is considered to have a much wider therapeutic potential for epilepsy compared with THC. CBD has anticonvulsant (Consroe et al, 1982, Martin et al, 1987Devinsky et al, 2014a), anti-inflammatory (Malfait et al, 2000;Li et al, 2013), and antitumorigenic activities (McAllister et al, 2011). Although CBD has a low affinity for both the CB 1 and CB 2 receptors, at high levels it can act as an indirect CB 1 antagonist and has been shown to affect the threshold of seizures in some animal studies (Wallace et al, 2003).…”