Ion channel TRPV1-dependent activation of PTP1B suppresses EGFR-associated intestinal tumorigenesis
Petrus R. de Jong, … , Maripat Corr, Eyal Raz
Petrus R. de Jong, … , Maripat Corr, Eyal Raz
Published August 1, 2014
Citation Information: J Clin Invest. 2014;124(9):3793-3806. https://doi.org/10.1172/JCI72340.
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Research Article Oncology

Ion channel TRPV1-dependent activation of PTP1B suppresses EGFR-associated intestinal tumorigenesis

Abstract

The intestinal epithelium has a high rate of turnover, and dysregulation of pathways that regulate regeneration can lead to tumor development; however, the negative regulators of oncogenic events in the intestinal epithelium are not fully understood. Here we identified a feedback loop between the epidermal growth factor receptor (EGFR), a known mediator of proliferation, and the transient receptor potential cation channel, subfamily V, member 1 (TRPV1), in intestinal epithelial cells (IECs). We found that TRPV1 was expressed by IECs and was intrinsically activated upon EGFR stimulation. Subsequently, TRPV1 activation inhibited EGFR-induced epithelial cell proliferation via activation of Ca2+/calpain and resulting activation of protein tyrosine phosphatase 1B (PTP1B). In a murine model of multiple intestinal neoplasia (ApcMin/+ mice), TRPV1 deficiency increased adenoma formation, and treatment of these animals with an EGFR kinase inhibitor reversed protumorigenic phenotypes, supporting a functional association between TRPV1 and EGFR signaling in IECs. Administration of a TRPV1 agonist suppressed intestinal tumorigenesis in ApcMin/+ mice, similar to — as well as in conjunction with — a cyclooxygenase-2 (COX-2) inhibitor, which suggests that targeting both TRPV1 and COX-2 has potential as a therapeutic approach for tumor prevention. Our findings implicate TRPV1 as a regulator of growth factor signaling in the intestinal epithelium through activation of PTP1B and subsequent suppression of intestinal tumorigenesis.

Authors

Petrus R. de Jong, Naoki Takahashi, Alexandra R. Harris, Jihyung Lee, Samuel Bertin, James Jeffries, Michael Jung, Jen Duong, Amy I. Triano, Jongdae Lee, Yaron Niv, David S. Herdman, Koji Taniguchi, Chang-Whan Kim, Hui Dong, Lars Eckmann, Stephanie M. Stanford, Nunzio Bottini, Maripat Corr, Eyal Raz

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Figure 2

TRPV1 signaling inhibits cell proliferation and EGFR activity in vivo.

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TRPV1 signaling inhibits cell proliferation and EGFR activity in vivo. (...
(A) Increased IEC proliferation in colons from naive Trpv1–/– versus WT mice, as shown by Ki67 immunostaining. (B) Increased EGFRY1068 phosphorylation in Trpv1–/– IECs was reversed by gefitinib treatment. Mice were treated with 2 doses of gefitinib (50 mg/kg, gavage) with a 6-hour interval, followed by IEC harvesting and Western blotting. Shown are representative results from 3 experiments. (C) Immunostaining for p-EGFRY1068 of distal colon tissues. (D) Quantification with ImageJ. 3 representative areas were used for analysis, with 3 mice per group. (E) Hyperproliferation of Trpv1–/– IECs was reversed by EGFR inhibition with gefitinib (50 mg/kg) for 5 consecutive days before tissue harvesting. (F) Quantification of Ki67+ cells by ImageJ (ImmunoRatio plugin). (G) Capsaicin administration suppressed transcription of EGFR target genes in a TRPV1-dependent manner, comparable to gefitinib. Mice received DMSO, capsaicin (3 mg/kg), gefitinib (50 mg/kg), or capsaicin plus gefitinib by gavage, and IECs were prepared 6 hours later. Shown is Q-PCR analysis for c-Fos or Fosl2, relative to the respective DMSO control. (H) Q-PCR analysis for c-Jun. (I) Generation of transgenic TRPV1IEC mice. (J) TRPV1fl/fl and TRPV1IEC mice were analyzed for p-EGFRY1068 by Western blotting. IEC-specific TRPV1 overexpression inhibited constitutive EGFR signaling in IECs. (K) IEC-specific TRPV1 overexpression suppressed EGF-induced EGFRY1068 phosphorylation in IECs. Data are mean ± SEM (D and F; n = 3 per group) or mean ± SD (G and H; n = 2 per group). *P < 0.05, t test (D) or ANOVA (F–H). Scale bars: 100 μm.