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J Nutr Biochem. 2015 Mar;26(3):250-8. doi: 10.1016/j.jnutbio.2014.10.013. Epub 2014 Dec 3.

Extravirgin olive oil up-regulates CB₁ tumor suppressor gene in human colon cancer cells and in rat colon via epigenetic mechanisms.

Author information

1
Faculty of Biosciences, University of Teramo, Teramo, Italy.
2
Faculty of Veterinary Medicine, University of Teramo, Teramo, Italy.
3
School of Pharmacy, Pharmacology Unit, University of Camerino, Camerino, MC, Italy.
4
Center of Integrated Research, Campus Bio-Medico University of Rome, Italy.
5
Departments of Oncology-Pathology Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
6
Faculty of Biosciences, University of Teramo, Teramo, Italy; European Center for Brain Research, Santa Lucia Foundation I.R.C.C.S., Rome, Italy.
7
Center of Integrated Research, Campus Bio-Medico University of Rome, Italy; European Center for Brain Research, Santa Lucia Foundation I.R.C.C.S., Rome, Italy. Electronic address: m.maccarrone@unicampus.it.
8
Faculty of Biosciences, University of Teramo, Teramo, Italy; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden. Electronic address: cdaddario@unite.it.

Abstract

Extravirgin olive oil (EVOO) represents the typical lipid source of the Mediterranean diet, an eating habit pattern that has been associated with a significant reduction of cancer risk. Diet is the more studied environmental factor in epigenetics, and many evidences suggest dysregulation of epigenetic pathways in cancer. The aim of our study was to investigate the effects of EVOO and its phenolic compounds on endocannabinoid system (ECS) gene expression via epigenetic regulation in both human colon cancer cells (Caco-2) and rats exposed to short- and long-term dietary EVOO. We observed a selective and transient up-regulation of CNR1 gene - encoding for type 1 cannabinoid receptor (CB₁) - that was evoked by exposure of Caco-2 cells to EVOO (100 ppm), its phenolic extracts (OPE, 50 μM) or authentic hydroxytyrosol (HT, 50 μM) for 24 h. None of the other major elements of the ECS (i.e., CB₂; GPR55 and TRPV1 receptors; and NAPE-PLD, DAGL, FAAH and MAGL enzymes) was affected at any time point. The stimulatory effect of OPE and HT on CB₁ expression was inversely correlated to DNA methylation at CNR1 promoter and was associated with reduced proliferation of Caco-2 cells. Interestingly, CNR1 gene was less expressed in Caco-2 cells when compared to normal colon mucosa cells, and again this effect was associated with higher level of DNA methylation at CNR1. Moreover, in agreement with the in vitro studies, we also observed a remarkable (~4-fold) and selective increase in CB₁ expression in the colon of rats receiving dietary EVOO supplementation for 10 days. Consistently, CpG methylation of rat Cnr1 promoter, miR23a and miR-301a, previously shown to be involved in the pathogenesis of colorectal cancer and predicted to target CB₁ mRNA, was reduced after EVOO administration down to ~50% of controls. Taken together, our findings demonstrating CB₁ gene expression modulation by EVOO or its phenolic compounds via epigenetic mechanism, both in vitro and in vivo, may provide a new therapeutic avenue for treatment and/or prevention of colon cancer.

KEYWORDS:

Bioactive lipids; Colon; Endocannabinoid system; Epigenetics; Hydroxytyrosol; Olive oil; Phenolic compounds

PMID:
25533906
DOI:
10.1016/j.jnutbio.2014.10.013
[Indexed for MEDLINE]

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