Proinflammatory Interleukin-33 Induces Dichotomic Effects on Cell Proliferation in Normal Gastric Epithelium and Gastric Cancer.

Laura Francesca Pisani,Beatrice Marinoni,Emanuele Asti,Maurizio Vecchi,Isabella Teani,Luigi Bonavina,Gian Eugenio Tontini,Carmine Gentile,Pasquale Creo,Luca Pastorelli,Nicoletta Nandi

doi:10.3390/ijms22115792

Abstract

Interleukin (IL)-33 is a member of the interleukin (IL)-1 family of cytokines linked to the development of inflammatory conditions and cancer in the gastrointestinal tract. This study is designed to investigate whether IL-33 has a direct effect on human gastric epithelial cells (GES-1), the human gastric adenocarcinoma cell line (AGS), and the gastric carcinoma cell line (NCI-N87) by assessing its role in the regulation of cell proliferation, migration, cell cycle, and apoptosis. Cell cycle regulation was also determined in ex vivo gastric cancer samples obtained during endoscopy and surgical procedures. Cell lines and tissue samples underwent stimulation with rhIL-33. Proliferation was assessed by XTT and CFSE assays, migration by wound healing assay, and apoptosis by caspase 3/7 activity assay and annexin V assay. Cell cycle was analyzed by means of propidium iodine assay, and gene expression regulation was assessed by RT-PCR profiling. We found that IL-33 has an antiproliferative and proapoptotic effect on cancer cell lines, and it can stimulate proliferation and reduce apoptosis in normal epithelial cell lines. These effects were also confirmed by the analysis of cell cycle gene expression, which showed a reduced expression of pro-proliferative genes in cancer cells, particularly in genes involved in G0/G1 and G2/M checkpoints. These results were confirmed by gene expression analysis on bioptic and surgical specimens. The aforementioned results indicate that IL-33 may be involved in cell proliferation in an environment- and cell-type-dependent manner.

Highlights

Gastric cancer is a leading cause of cancer-related deaths and is the fourth most common type of cancer in the world [1,2]
In order to unravel some of these aspects, we investigate whether IL-33 has effects on the cell cycle and apoptosis in in vitro and ex vivo settings
By carrying out real-time PCR and Western blots, we have demonstrated the expression of IL-33 and its receptor ST2 in the GES-1, AGS, and NCI-N87 cell lines to validate our in vitro models (Figure S1)

Summary

Introduction

Gastric cancer is a leading cause of cancer-related deaths and is the fourth most common type of cancer in the world [1,2]. Major risks for the development of gastric cancer are Helicobacter pylori and Epstein–Barr virus infections, family history, dietary factors, alcohol consumption, smoking, and chronic gastritis [2,3]. Chronic inflammation plays a major role, and proinflammatory cytokines appear to promote progression from gastritis to cancer; in particular, the interleukin (IL)-1 family members, such as IL-1β and IL-18, have been shown to induce gastric carcinogenesis in animal models [6,7]. IL-33 is broadly expressed in many tissues, but its expression appears to be restricted by cell type [6]. Expression analysis of human and mouse cDNA libraries have revealed a high expression of IL-33 in barrier epithelia within organs/tissues in direct contact with the external environment, including skin, airway, and gut epithelia, suggesting a possible role of this cytokine in early immune responses against invasive pathogens [6]. IL-33 is predominantly present in stromal cells, including fibroblasts, smooth muscle cells, and endothelial and epithelial cells [11], and in restricted populations of hematopoietic cells, such as macrophages [6,12]

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Discussion

Conclusion