Cannabinoid Receptor Activation Induces Apoptosis through Tumor Necrosis Factor α–Mediated Ceramide De novo Synthesis in Colon Cancer Cells
- Fabio Cianchi1,
- Laura Papucci2,
- Nicola Schiavone2,
- Matteo Lulli2,
- Lucia Magnelli2,
- Maria Cristina Vinci3,
- Luca Messerini4,
- Clementina Manera6,
- Elisa Ronconi5,
- Paola Romagnani5,
- Martino Donnini2,
- Giuliano Perigli1,
- Giacomo Trallori1,
- Elisabetta Tanganelli2,
- Sergio Capaccioli2 and
- Emanuela Masini3
Authors’ Affiliations: Departments of 1Medical and Surgical Critical Care, 2Experimental Pathology and Oncology, 3Preclinical and Clinical Pharmacology, 4Human Pathology and Oncology, and 5Excellence Center for Research, Transfer and High Education De Novo Therapies, University of Florence, Florence, Italy; and 6Department of Pharmaceutical Sciences, University of Pisa, Pisa, Italy
- Requests for reprints:
Sergio Capaccioli, Dipartimento Patologia e Oncologia Sperimentale Medical School, University of Florence, Viale G.B. Morgagni 85, Firenze 50134, Italy. Phone: 3955-4598208; Fax: 3955-4598900; E-mail: firstname.lastname@example.org.
Purpose: Cannabinoids have been recently proposed as a new family of potential antitumor agents. The present study was undertaken to investigate the expression of the two cannabinoid receptors, CB1 and CB2, in colorectal cancer and to provide new insight into the molecular pathways underlying the apoptotic activity induced by their activation.
Experimental Design: Cannabinoid receptor expression was investigated in both human cancer specimens and in the DLD-1 and HT29 colon cancer cell lines. The effects of the CB1 agonist arachinodyl-2′-chloroethylamide and the CB2 agonist N-cyclopentyl-7-methyl-1-(2-morpholin-4-ylethyl)-1,8-naphthyridin-4(1H)-on-3-carboxamide (CB13) on tumor cell apoptosis and ceramide and tumor necrosis factor (TNF)-α production were evaluated. The knockdown of TNF-α mRNA was obtained with the use of selective small interfering RNA.
Results: We show that the CB1 receptor was mainly expressed in human normal colonic epithelium whereas tumor tissue was strongly positive for the CB2 receptor. The activation of the CB1 and, more efficiently, of the CB2 receptors induced apoptosis and increased ceramide levels in the DLD-1 and HT29 cells. Apoptosis was prevented by the pharmacologic inhibition of ceramide de novo synthesis. The CB2 agonist CB13 also reduced the growth of DLD-1 cells in a mouse model of colon cancer. The knockdown of TNF-α mRNA abrogated the ceramide increase and, therefore, the apoptotic effect induced by cannabinoid receptor activation.
Conclusions: The present study shows that either CB1 or CB2 receptor activation induces apoptosis through ceramide de novo synthesis in colon cancer cells. Our data unveiled, for the first time, that TNF-α acts as a link between cannabinoid receptor activation and ceramide production.
Grant support: Italian Ministry of University, Scientific and Technological Research, the Ente Cassa di Risparmio di Firenze, and the Associazione Italiana Ricerca sul Cancro.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Note: Supplementary data for this article are available at Clinical Cancer Research Online (http://clincancerres.aacrjournals.org/).
- Accepted July 28, 2008.
- Received March 27, 2008.
- Revision received July 25, 2008.