Epithelial-mesenchymal transition leads to NK cell–mediated metastasis-specific immunosurveillance in lung cancer
Peter J. Chockley, … , Theodore J. Standiford, Venkateshwar G. Keshamouni
Peter J. Chockley, … , Theodore J. Standiford, Venkateshwar G. Keshamouni
Published January 11, 2018
Citation Information: J Clin Invest. 2018;128(4):1384-1396. https://doi.org/10.1172/JCI97611.
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Research Article Immunology Oncology

Epithelial-mesenchymal transition leads to NK cell–mediated metastasis-specific immunosurveillance in lung cancer

Abstract

During epithelial-mesenchymal transition (EMT) epithelial cancer cells transdifferentiate into highly motile, invasive, mesenchymal-like cells, giving rise to disseminating tumor cells. Few of these disseminated cells successfully metastasize. Immune cells and inflammation in the tumor microenvironment were shown to drive EMT, but few studies investigated the consequences of EMT for tumor immunosurveillance. In addition to initiating metastasis, we demonstrate that EMT confers increased susceptibility to natural killer (NK) cells and contributes, in part, to the inefficiency of the metastatic process. Depletion of NK cells allowed spontaneous metastasis without affecting primary tumor growth. EMT-induced modulation of E-cadherin and cell adhesion molecule 1 (CADM1) mediated increased susceptibility to NK cytotoxicity. Higher CADM1 expression correlates with improved patient survival in 2 lung and 1 breast adenocarcinoma patient cohorts and decreased metastasis. Our observations reveal a novel NK-mediated, metastasis-specific immunosurveillance in lung cancer and present a window of opportunity for preventing metastasis by boosting NK cell activity.

Authors

Peter J. Chockley, Jun Chen, Guoan Chen, David G. Beer, Theodore J. Standiford, Venkateshwar G. Keshamouni

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Figure 5

CADM1 expression is modulated by EMT-MET cycling and mediates tumor cell susceptibility to NK cytotoxicity.

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CADM1 expression is modulated by EMT-MET cycling and mediates tumor cell...
(A) A549 cells were treated with TGF-β (5 ng/ml) to induce EMT, and total proteins were extracted at the indicated times. After 72 hours, cells were washed 3 times and replaced with fresh media to induce mesenchymal-epithelial transition (MET), and total proteins were extracted at the indicated times. Protein expression of E-cad, CADM1, vimentin, and GAPDH was assessed by Western immunoblotting. (B) A549 cells treated with and without TGF-β for 72 hours were fixed and assessed for E-cad and CADM1 expression by immunofluorescence staining. Scale bars: 100 μm. (C) To stably knock out CADM1, Cas9-expressing A549 cells were transduced with lentiviruses expressing 3 different CADM1-specific CRISPR sgRNAs and a nontargeting (NT) control sgRNA. CADM1 knockout was assessed by Western immunoblotting using 2 different CADM1 antibodies raised against C-terminal (CADM1-c) and N-terminal (CADM1-n) portions. (D and E) Susceptibility of CADM1-KO A549 cells to NK cytotoxicity was assessed by coculturing with either NK92mi cells or primary human blood–derived NK cells from 4 different donors. In D, mean ± SEM is shown; 2-way ANOVA with Tukey’s post hoc analysis was performed, **P < 0.01, ****P < 0.0001. In E, EMT controls are from Figure 1H, as these experiments were performed simultaneously. Mean ± SEM is shown; 2-tailed, unpaired t tests were performed, *P < 0.05, **P < 0.01.