Gastroenterology

Gastroenterology

Volume 125, Issue 3, September 2003, Pages 677-687
Gastroenterology

Clinical-alimentary tract
Possible endocannabinoid control of colorectal cancer growth

https://doi.org/10.1016/S0016-5085(03)00881-3Get rights and content

Abstract

Background & Aims: The endocannabinoids anandamide and 2-arachidonoylglycerol (2-AG) inhibit cancer cell proliferation by acting at cannabinoid receptors (CBRs). We studied (1) the levels of endocannabinoids, cannabinoid CB1 and CB2 receptors, and fatty acid amide hydrolase (FAAH, which catalyzes endocannabinoid hydrolysis) in colorectal carcinomas (CRC), adenomatous polyps, and neighboring healthy mucosa; and (2) the effects of endocannabinoids, and of inhibitors of their inactivation, on human CRC cell proliferation. Methods: Tissues were obtained from 21 patients by biopsy during colonoscopy. Endocannabinoids were measured by liquid chromatography-mass spectrometry (LC-MS). CB1, CB2, and FAAH expression were analyzed by RT-PCR and Western immunoblotting. CRC cell lines (CaCo-2 and DLD-1) were used to test antiproliferative effects. Results: All tissues and cells analyzed contain anandamide, 2-AG, CBRs, and FAAH. The levels of the endocannabinoids are 3- and 2-fold higher in adenomas and CRCs than normal mucosa. Anandamide, 2-AG, and the CBR agonist HU-210 potently inhibit CaCo-2 cell proliferation. This effect is blocked by the CB1 antagonist SR141716A, but not by the CB2 antagonist SR144528, and is mimicked by CB1-selective, but not CB2-selective, agonists. In DLD-1 cells, both CB1 and CB2 receptors mediate inhibition of proliferation. Inhibitors of endocannabinoid inactivation enhance CaCo-2 cell endocannabinoid levels and block cell proliferation, this effect being antagonized by SR141716A. CaCo-2 cell differentiation into noninvasive cells results in increased FAAH expression, lower endocannabinoid levels, and no responsiveness to cannabinoids. Conclusions: Endocannabinoid levels are enhanced in transformed colon mucosa cells possibly to counteract proliferation via CBRs. Inhibitors of endocannabinoid inactivation may prove useful anticancer agents.

Section snippets

Drugs

AEA and 2-AG were purchased from Cayman Chemicals, and ACEA, Met-Fluoro-anandamide, and BML-190 from Tocris. HU-210 was a kind gift from Prof. R. Mechoulam, Hebrew University of Jerusalem, and SR14176A and SR144528 were donated by Sanofi Recherche. Indomethacin N-methyl-ester was obtained from Sigma. VDM-11, VDM-13, and arachidonoyl-serotonin were synthesized from the corresponding amines and arachidonoyl-chloride, as described previously.21

Biopsy

Biopsy specimens were obtained in agreement with

Endocannabinoid levels and CB1, CB2, and FAAH expression in human colorectal tissues

We found that human colon mucosa tissues contain both AEA and 2-AG (Figure 1A) , as determined by using an ultrasensitive LC-MS technique, and express mRNA transcripts of the size expected for CB1 and CB2 receptors as well as FAAH (Figure 1B), as determined by RT-PCR. The finding of CB1 receptors was also confirmed by Western immunoblot of proteins from biopsy specimens of normal colon mucosa (not shown). The levels of both AEA and 2-AG increased when passing from normal mucosa to transformed

Discussion

We found that human colon mucosa tissues contain both AEA and 2-AG and express CB1 and CB2 receptors as well as FAAH. The endocannabinoids and FAAH previously have been described to occur in mouse and rat whole colon,24, 25 but we found here that the levels of both AEA and 2-AG increase dramatically when passing from normal mucosa to adenomatous polyps and then slightly decrease in CRC tissue. These changes are likely to result in corresponding changes in endocannabinoid tissue concentrations.

Acknowledgements

The authors thank Drs. Filomena Fezza and Pierangelo Orlando for valuable assistance and Dr. Gabriella Caruso (I.R.C.C.S. “S. de Bellis,” Bari, Italy) for the kind gift of DLD-1 cells.

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  • Cited by (0)

    Supported by funds from the Italian National Research Council, MURST (3933 to V.D.M.) and the Associazione Italiana per la Ricerca sul Cancro (to M.B.).

    1

    A.L. and T.B. contributed equally to this work.

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