Loss of gastrokine-2 drives premalignant gastric inflammation and tumor progression
Trevelyan R. Menheniott, … , Louise M. Judd, Andrew S. Giraud
Trevelyan R. Menheniott, … , Louise M. Judd, Andrew S. Giraud
Published March 14, 2016
Citation Information: J Clin Invest. 2016;126(4):1383-1400. https://doi.org/10.1172/JCI82655.
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Research Article Oncology

Loss of gastrokine-2 drives premalignant gastric inflammation and tumor progression

Abstract

Chronic mucosal inflammation is associated with a greater risk of gastric cancer (GC) and, therefore, requires tight control by suppressive counter mechanisms. Gastrokine-2 (GKN2) belongs to a family of secreted proteins expressed within normal gastric mucosal cells. GKN2 expression is frequently lost during GC progression, suggesting an inhibitory role; however, a causal link remains unsubstantiated. Here, we developed Gkn2 knockout and transgenic overexpressing mice to investigate the functional impact of GKN2 loss in GC pathogenesis. In mouse models of GC, decreased GKN2 expression correlated with gastric pathology that paralleled human GC progression. At baseline, Gkn2 knockout mice exhibited defective gastric epithelial differentiation but not malignant progression. Conversely, Gkn2 knockout in the IL-11/STAT3-dependent gp130F/F GC model caused tumorigenesis of the proximal stomach. Additionally, gastric immunopathology was accelerated in Helicobacter pylori–infected Gkn2 knockout mice and was associated with augmented T helper cell type 1 (Th1) but not Th17 immunity. Heightened Th1 responses in Gkn2 knockout mice were linked to deregulated mucosal innate immunity and impaired myeloid-derived suppressor cell activation. Finally, transgenic overexpression of human gastrokines (GKNs) attenuated gastric tumor growth in gp130F/F mice. Together, these results reveal an antiinflammatory role for GKN2, provide in vivo evidence that links GKN2 loss to GC pathogenesis, and suggest GKN restoration as a strategy to restrain GC progression.

Authors

Trevelyan R. Menheniott, Louise O’Connor, Yok Teng Chionh, Jan Däbritz, Michelle Scurr, Benjamin N. Rollo, Garrett Z. Ng, Shelley Jacobs, Angelique Catubig, Bayzar Kurklu, Stephen Mercer, Toshinari Minamoto, David E. Ong, Richard L. Ferrero, James G. Fox, Timothy C. Wang, Philip Sutton, Louise M. Judd, Andrew S. Giraud

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Figure 1

Loss of GKN2 expression in human and mouse GC progression.

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Loss of GKN2 expression in human and mouse GC progression. (A) QRT-PCR a...
(A) QRT-PCR analysis of GKN2 mRNA in human GC. Scatter plots show mRNA fold changes for H. pylori–infected tissue (HP; n = 16), premalignant tissue adjacent to tumor with intestinal metaplasia (IM; n = 28), and GC tissue (n = 28) relative to normal (N; n = 6) gastric epithelial tissues. (B) Representative photomicrographs showing GKN2 immunostaining in human gastric tissues (see above). Normal and H. pylori–infected tissue show antral mucosa. Scale bar: 50 μm. Intestinal metaplasia shows corpus mucosa; presence of goblet cells is confirmed by AB-PAS staining of an adjacent section. GC shows adenocarcinoma in corpus mucosa. Scale bar: 100 μm (first and second columns and top image fourth column); 50 μm (third column and bottom image fourth column). (C) Immunoblots of mouse GKN2 protein. GAPDH verifies protein integrity. Two GKN2 bands represent unprocessed precursor (20-kDa) and secreted mature (18-kDa) protein, respectively. Oes, oesophagus; Duo, duodenum; PSI, proximal small intestine; MSI, middle small intestine; DSI, distal small intestine. (D) Immunofluorescent localization of mouse GKN2 protein in corpus and antrum mucosa. Scale bar: 50 μm (first and third image) and 25 μm (second and fourth image). (E) QRT-PCR analysis of Gkn2 mRNA in H. pylori SS1–infected WT (C57BL/6) mouse corpus, antrum, or whole stomach at 7 days (7 d), 2 months (2 mo), or 12 months (12 mo). Box plots show median mRNA fold change relative to uninfected mice. (F) QRT-PCR analysis of mouse genetic models described in B. (E and F) In box-and-whisker plots, horizontal bars indicate the medians, boxes indicate 25th to 75th percentiles, and whiskers indicate 10th and 90th percentiles. P values were determined using a 2-tailed Student’s t test: *P < 0.05; ***P < 0.001.