The endogenous cannabinoid, anandamide, induces COX-2-dependent cell death in apoptosis-resistant colon cancer cells

• Published in: International journal of oncology Vol. 37; no. 1; pp. 187 - 193
• Main Authors: PATIOS, Helena A, GREENHOUGH, Alexander, HICKS, Diane J, MANAL AL KHARUSI, COLLARD, Tracey J, LANE, Jon D, PARASKEVA, Christos, WILLIAMS, Ann C
• Format: Journal Article
• Language: English
• Published: Athens Editorial Academy of the International Journal of Oncology 01-07-2010
• Subjects: Apoptosis - drug effects; Apoptosis - genetics; Arachidonic Acids - pharmacology; bcl-2-Associated X Protein - genetics; Biological and medical sciences; Cannabinoid Receptor Modulators - pharmacology; Carcinoma - genetics; Carcinoma - pathology; Cell Death - drug effects; Cell Death - genetics; Cell Line, Tumor; Colonic Neoplasms - genetics; Colonic Neoplasms - pathology; Cyclooxygenase 2 - genetics; Cyclooxygenase 2 - physiology; Cyclooxygenase 2 Inhibitors - pharmacology; Drug Evaluation, Preclinical; Drug Resistance, Neoplasm - genetics; Endocannabinoids; Gastroenterology. Liver. Pancreas. Abdomen; Gene Expression Regulation, Neoplastic - drug effects; HCT116 Cells; HT29 Cells; Humans; Medical sciences; Polyunsaturated Alkamides - pharmacology; RNA, Small Interfering - pharmacology; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Tumors; Up-Regulation - drug effects; Up-Regulation - genetics; Rectal disease; Enzyme; Arachidonic acid derivatives; Colorectal carcinoma; Cyclooxygenase 2; Colorectal cancer; cyclooxygenase-2; Malignant tumor; Cannabinoid; Anandamide; Colonic disease; Resistance; Colon cancer; Cancerology; Endogenous; Cell death; arachidonoylethanolamide (anandamide, AEA); Digestive diseases; Intestinal disease; non-apoptotic cell death; Oxidoreductases; Tumor cell; Cancer; Apoptosis
• ISSN: 1019-6439; 1791-2423
• DOI: 10.3892/ijo_00000666

Despite recent advances in understanding colorectal tumour biology, there is still a need to improve the 5-year survival rate of patients with colorectal cancer as approximately 40% of patients presenting with advanced disease will remain resistant to therapy. One of the major contributing factors in resistance to therapy is the failure of colorectal tumour cells to undergo apoptosis. Hence there is an urgent need to develop novel therapeutic approaches that can target apoptosis-resistant cells. To this end, we investigated the potential efficacy of the endogenous cannabinoid anandamide to induce cell death in apoptosis-resistant colon cancer cells. Here, for the first time, we show that anandamide can induce cell death in the apoptosis-resistant HCT116 Bax-/- colorectal cell line. Importantly, we provide direct genetic evidence that this induction of cell death is dependent on COX-2 expression. Interestingly, increased COX-2 expression also sensitised the SW480 colorectal cancer cell line (low endogenous COX-2) to anandamide-induced death, whereas COX-2 suppression by RNAi inhibited anandamide-induced cell death in the HCA7 colorectal cancer cell line (high endogenous COX-2 expression). This COX-2-dependent death was independent of cannabinoid receptor engagement (CB1 or CB2), and not a direct consequence of reactive oxygen species (ROS) formation. This study demonstrates a novel utilisation for COX-2 expression, targeting apoptotic defective colorectal cancer cells for destruction by anandamide. As COX-2 is not expressed in the normal colorectal epithelium, but highly expressed in colorectal tumours and apoptosis resistance contributes to treatment failure, these data suggest that anandamide has the potential to be an effective therapeutic in colorectal cancer.