Increased expression of TIMP-1 mediates an anti-invasive effect of cannabinoids. Cannabinoids may therefore offer a therapeutic option in the treatment of highly invasive cancers.

Although cannabinoids exhibit a broad variety of anticarcinogenic effects, their potential use in cancer therapy is limited by their psychoactive effects. Here we evaluated the impact of cannabidiol, a plant-derived non-psychoactive cannabinoid, on cancer cell invasion. Using Matrigel invasion assays we found a cannabidiol-driven impaired invasion of human cervical cancer (HeLa, C33A) and human lung cancer cells (A549) that was reversed by antagonists to both CB 1 and CB 2 receptors as well as to transient receptor potential vanilloid 1 (TRPV1). Additionally, in vivo studies in thymic-aplastic nude mice revealed a significant inhibition of A549 lung metastasis in cannabidiol-treated animals as compared to vehicle-treated controls.Altogether, these findings provide a novel mechanism underlying the anti-invasive action of cannabidiol and imply its use as a therapeutic option for the treatment of highly invasive cancers. Page 3 of 40A c c e p t e d M a n u s c r i p t 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

The antitumorigenic mechanism of cannabidiol is still controversial. This study investigates the role of COX-2 and PPAR-g in cannabidiol's proapoptotic and tumor-regressive action. In lung cancer cell lines (A549, H460) and primary cells from a patient with lung cancer, cannabidiol elicited decreased viability associated with apoptosis. Apoptotic cell death by cannabidiol was suppressed by NS-398 (COX-2 inhibitor), GW9662 (PPAR-g antagonist), and siRNA targeting COX-2 and PPAR-g. Cannabidiol-induced apoptosis was paralleled by upregulation of COX-2 and PPAR-g mRNA and protein expression with a maximum induction of COX-2 mRNA after 8 hours and continuous increases of PPAR-g mRNA when compared with vehicle. In response to cannabidiol, tumor cell lines exhibited increased levels of COX-2-dependent prostaglandins (PG) among which PGD 2 and 15-deoxy-D 12,14 -PGJ 2 (15d-PGJ 2 ) caused a translocation of PPAR-g to the nucleus and induced a PPAR-g-dependent apoptotic cell death. Moreover, in A549-xenografted nude mice, cannabidiol caused upregulation of COX-2 and PPAR-g in tumor tissue and tumor regression that was reversible by GW9662. Together, our data show a novel proapoptotic mechanism of cannabidiol involving initial upregulation of COX-2 and PPAR-g and a subsequent nuclear translocation of PPAR-g by COX-2-dependent PGs. Mol Cancer Ther; 12(1); 69-82. Ó2012 AACR.

Cannabinoids inhibit cancer cell invasion via increasing tissue inhibitor of matrix metalloproteinases-1 (TIMP-1). This study investigates the role of intercellular adhesion molecule-1 (ICAM-1) within this action. In the lung cancer cell lines A549, H358, and H460, cannabidiol (CBD; 0.001-3 μM) elicited concentration-dependent ICAM-1 up-regulation compared to vehicle via cannabinoid receptors, transient receptor potential vanilloid 1, and p42/44 mitogen-activated protein kinase. Up-regulation of ICAM-1 mRNA by CBD in A549 was 4-fold at 3 μM, with significant effects already evident at 0.01 μM. ICAM-1 induction became significant after 2 h, whereas significant TIMP-1 mRNA increases were observed only after 48 h. Inhibition of ICAM-1 by antibody or siRNA approaches reversed the anti-invasive and TIMP-1-upregulating action of CBD and the likewise ICAM-1-inducing cannabinoids Δ(9)-tetrahydrocannabinol and R(+)-methanandamide when compared to isotype or nonsilencing siRNA controls. ICAM-1-dependent anti-invasive cannabinoid effects were confirmed in primary tumor cells from a lung cancer patient. In athymic nude mice, CBD elicited a 2.6- and 3.0-fold increase of ICAM-1 and TIMP-1 protein in A549 xenografts, as compared to vehicle-treated animals, and an antimetastatic effect that was fully reversed by a neutralizing antibody against ICAM-1 [% metastatic lung nodules vs. isotype control (100%): 47.7% for CBD + isotype antibody and 106.6% for CBD + ICAM-1 antibody]. Overall, our data indicate that cannabinoids induce ICAM-1, thereby conferring TIMP-1 induction and subsequent decreased cancer cell invasiveness.

The endocannabinoid system has emerged as an important target for the treatment of many diverse diseases. In addition to the well-established palliative effects of cannabinoids in cancer therapy, phytocannabinoids, synthetic cannabinoid compounds and inhibitors of endocannabinoid degradation have attracted attention as possible systemic anticancer drugs. Results emerging from preclinical studies suggest cannabinoids elicit effects at different levels of cancer progression, including inhibition of proliferation, neovascularization, invasion and chemoresistance, induction of apoptosis and autophagy as well as enhancement of tumour immune surveillance. Although the clinical use of cannabinoid receptor ligands is limited by their psychoactivity, non-psychoactive compounds, such as cannabidiol, have gained attention due to preclinically established anticancer properties and a favourable risk-to-benefit profile. Thus, cannabinoids may complement the currently used collection of chemotherapeutic agents, as a broadly diversified option for cancer treatment, while counteracting some of their severe side effects.