Paracrine Stimulation of P2X7 Receptor by ATP Activates a Proliferative Pathway in Ovarian Carcinoma Cells

Authors

  • Francisco G. Vázquez-Cuevas,

    Corresponding author
    1. Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, México
    • Correspondence to: Dr. Francisco Gabriel Vázquez-Cuevas, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Juriquilla Querétaro, CP 76230, Mexico.

      E-mail: fvazquezc132005@yahoo.com.mx

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  • Angélica S. Martínez-Ramírez,

    1. Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, México
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  • Leticia Robles-Martínez,

    1. Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, México
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  • Edith Garay,

    1. Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, México
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  • Alejandro García-Carrancá,

    1. Laboratorio de Virus y Cáncer Unidad de Investigación Biomédica en Cáncer, Instituto de Investigaciones Biomédicas-Universidad Nacional Autónoma de México, DF, México
    2. División de Investigación Básica, Instituto Nacional de Cancerología, Secretaría de Salud, México, Tlalpan, DF, México
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  • Delia Pérez-Montiel,

    1. Departamento de Patología, Instituto Nacional de Cancerología, Tlalpan, DF, México
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  • Carolina Castañeda-García,

    1. Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, México
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  • Rogelio O. Arellano

    1. Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, México
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ABSTRACT

P2X7 is a purinergic receptor-channel; its activation by ATP elicits a broad set of cellular actions, from apoptosis to signals for survival. Here, P2X7 expression and function was studied in human ovarian carcinoma (OCA) cells, and biopsies from non-cancerous and cancer patients were analyzed by immunohistochemistry. Ovarian surface epithelium in healthy tissue expressed P2X7 at a high level that was maintained throughout the cancer. The cell lines SKOV-3 and CAOV-3 were used to investigate P2X7 functions in OCA. In SKOV-3 cells, selective stimulation of P2X7 by 2′(3′)-O-(4-benzoylbenzoyl) adenosine-5′-triphosphate (BzATP) induced a dose-dependent increase of intracellular Ca2+ concentration ([Ca2+]i) but not cell death. Instead, BzATP increased the levels of phosphorylated ERK and AKT (pERK and pAKT), with an EC50 of 44 ± 2 and 1.27 ± 0.5 μM, respectively; 10 μM BzATP evoked a maximum effect within 15 min that lasted for 120 min. Interestingly, basal levels of pERK and pAKT were decreased in the presence of apyrase in the medium, strongly suggesting an endogenous, ATP-mediated phenomenon. Accordingly: (i) mechanically stimulated cells generated a [Ca2+]i increase that was abolished by apyrase; (ii) apyrase induced a decrease in culture viability, as measured by the MTS assay for mitochondrial activity; and (iii) incubation with 10 μM AZ10606120, a specific P2X7 antagonist and transfection with the dominant negative P2X7 mutant E496A, both reduced cell viability to 70.1 ± 8.9% and to 76.5 ± 5%, respectively, of control cultures. These observations suggested that P2X7 activity was auto-induced through ATP efflux; this increased pERK and pAKT levels that generated a positive feedback on cell viability. J. Cell. Biochem. 115: 1955–1966, 2014. © 2014 Wiley Periodicals, Inc.

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