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Am J Transl Res 2013;5(1):69-79

Original Article
Physically disconnected non-diffusible cell-to-cell communication be-
tween neuroblastoma SH-SY5Y and DRG primary sensory neurons

Victor V Chaban, Taehoon Cho, Christopher B Reid, Keith C Norris

Life Sciences Institute, Charles R. Drew University of Medicine and Science, Los Angeles, USA; Department of
Medicine, Geffen School of Medicine, UCLA, Los Angeles, USA

Received October 12, 2012; Accepted December 17, 2012; Epub January 21, 2013; Published January 30, 2013

Abstract: Background: Cell-cell communication occurs via a variety of mechanisms, including long distances
(hormonal), short distances (paracrine and synaptic) or direct coupling via gap junctions, antigen presentation, or
ligand-receptor interactions. We evaluated the possibility of neuro-hormonal independent, non-diffusible,
physically disconnected pathways for cell-cell communication using dorsal root ganglion (DRG) neurons.
Methods: We assessed intracellular calcium ([Ca2+]) in primary culture DRG neurons that express ATP-sensitive
P2X3, capsaicin-sensitive TRPV1 receptors modulated by estradiol. Physically disconnected (dish-in-dish
system; inner chamber enclosed) mouse DRG were cultured for 12 hours near: a) media alone (control 1), b)
mouse DRG (control 2), c) human neuroblastoma SHSY-5Y cells (cancer intervention), or d) mouse DRG treated
with KCl (apoptosis intervention). Results: Chemosensitive receptors [Ca2+]і signaling did not differ between
control 1 and 2. ATP (10 µM) and capsaicin (100nM) increased [Ca2+]і transients to 425.86 + 49.5 nM, and 399.21
± 44.5 nM, respectively. 17β-estradiol (100 nM) exposure reduced ATP (171.17 ± 48.9 nM) and capsaicin (175.01
±34.8 nM) [Ca2+]і transients. The presence of cancer cells reduced ATP- and capsaicin-induced [Ca2+]і by >50%
(p<0.05) and abolished the 17β-estradiol effect. By contrast, apoptotic DRG cells increased initial ATP-induced
[Ca2+]і, flux four fold and abolished subsequent [Ca2+]і, responses to ATP stimulation (p<0.001). Capsaicin
(100nM) induced [Ca2+]і responses were totally abolished. Conclusion: The local presence of apoptotic DRG or
human neuroblastoma cells induced differing abnormal ATP and capsaicin-mediated [Ca2+]і fluxes in normal
DRG. These findings support physically disconnected, non-diffusible cell-to-cell signaling. Further studies are
needed to delineate the mechanism(s) of and model(s) of communication. (AJTR1210003).

Keywords: Cell-cell communication, TRPV1, P2X3, DRG, SH-SY5Y

Address correspondence to: Dr. Keith Norris, Charles R. Drew University of Medicine and Science, 1731 East
120 St., Los Angeles, CA 90059, USA. E-mail: keithnorris@cdrewu.edu