Submitted on May 7, 2004
Accepted on December 28, 2004
P2X and P2Y purinergic receptors on human intestinal epithelial carcinoma cells: effects of extracellular nucleotides on apoptosis and cell proliferation
Robson Coutinho-Silva1*, Lynn Stahl2, Kwok-Kuen Cheung3, Nathalia Enes de Campos4, Carolina de Oliveira Souza4, David M. Ojcius5, and Geoffrey Burnstock3
1 Autonomic Neuroscience Institute, Royal Free and University College Medical School, London, United Kingdom; Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
2 Institut Jacques Monod, Universite Paris 7, Paris, France
3 Autonomic Neuroscience Institute, Royal Free and University College Medical School, London, United Kingdom
4 Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
5 Institut Jacques Monod, Universite Paris 7, Paris, France; School of Natural Sciences, University of California, California, USA
* To whom correspondence should be addressed. E-mail: rcsilva{at}biof.ufrj.br.
Extracellular nucleotides interact with purinergic receptors, which regulate ion transport
in a variety of epithelia. Using two different human epithelial carcinoma cell lines
(HCT8 and Caco-2), we have shown by RT-PCR that the cells express mRNA for P2X1,
P2X3, P2X4, P2X5, P2X6, P2X7, P2Y1, P2Y2, P2Y4, P2Y6, P2Y11 and P2Y12 receptors.
Protein expression for P2Y1 and P2Y2 receptors was also demonstrated
immunohistochemically and P2X receptor subtype protein was present in the following
decreasing order: P2X4 > P2X7 > P2X1 > P2X3 > P2X6 > P2X5 >> P2X2. The functional
presence of P2X7, P2Y1, P2Y2, and P2Y4 receptors was shown based on the effect of
extracellular nucleotides on apoptosis or cell proliferation, and measurement of
nucleotide-dependent calcium fluxes using a Fluorometric Imaging Plate Reader in the
presence of different selective agonists and antagonists. ATP, at high concentrations,
induced apoptosis through ligation of P2X7 and P2Y1 receptors; conversely, ATP, at
lower concentrations, and UTP stimulated proliferation, probably acting via P2Y2
receptors. We therefore propose that stimulation or dysfunction of purinergic receptors
may contribute at least partially to modulation of epithelial carcinoma cell proliferation
and apoptosis.
