Remodeling of purinergic receptor-mediated Ca 2+ signaling as a consequence of EGF-induced epithelial-mesenchymal transition in breast cancer cells

Davis, Felicity M., Kenny, Paraic A., Soo, Eliza T.L., van Denderen, Bryce J.W., Thompson, Erik W., Cabot, Peter J., Parat, Marie-Odile, Roberts-Thomson, Sarah J., & Monteith, Gregory R. (2011) Remodeling of purinergic receptor-mediated Ca 2+ signaling as a consequence of EGF-induced epithelial-mesenchymal transition in breast cancer cells. PLoS ONE, 6(8), e23464.

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Abstract

Background

The microenvironment plays a pivotal role in tumor cell proliferation, survival and migration. Invasive cancer cells face a new set of environmental challenges as they breach the basement membrane and colonize distant organs during the process of metastasis. Phenotypic switching, such as that which occurs during epithelial-mesenchymal transition (EMT), may be associated with a remodeling of cell surface receptors and thus altered responses to signals from the tumor microenvironment.

Methodology/Principal Findings

We assessed changes in intracellular Ca 2+ in cells loaded with Fluo-4 AM using a fluorometric imaging plate reader (FLIPR TETRA) and observed significant changes in the potency of ATP (EC 50 0.175 μM (-EGF) versus 1.731 μM (+EGF), P<0.05), and the nature of the ATP-induced Ca 2+ transient, corresponding with a 10-fold increase in the mesenchymal marker vimentin (P<0.05). We observed no change in the sensitivity to PAR2-mediated Ca 2+ signaling, indicating that these alterations are not simply a consequence of changes in global Ca 2+ homeostasis. To determine whether changes in ATP-mediated Ca 2+ signaling are preceded by alterations in the transcriptional profile of purinergic receptors, we analyzed the expression of a panel of P2X ionotropic and P2Y metabotropic purinergic receptors using real-time RT-PCR and found significant and specific alterations in the suite of ATP-activated purinergic receptors during EGF-induced EMT in breast cancer cells. Our studies are the first to show that P2X 5 ionotropic receptors are enriched in the mesenchymal phenotype and that silencing of P2X 5 leads to a significant reduction (25%, P<0.05) in EGF-induced vimentin protein expression.

Conclusions

The acquisition of a new suite of cell surface purinergic receptors is a feature of EGF-mediated EMT in MDA-MB-468 breast cancer cells. Such changes may impart advantageous phenotypic traits and represent a novel mechanism for the targeting of cancer metastasis.

Impact and interest:

23 citations in Scopus
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ID Code: 72122
Item Type: Journal Article
Refereed: Yes
Additional Information: Cited By (since 1996):14
Export Date: 6 May 2014
Source: Scopus
Art. No.: e23464
PubMed ID: 21850275
Additional URLs:
DOI: 10.1371/journal.pone.0023464
ISSN: 1932-6203
Copyright Owner: Copyright 2011 Davis et al.
Copyright Statement: This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Deposited On: 26 May 2014 04:32
Last Modified: 27 May 2014 02:57

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