Tumor-associated macrophages regulate gastric cancer cell invasion and metastasis through TGFβ2/NF-κB/Kindlin-2 axis.

,Zhu Wang,Yansen Li,Kewei Jiang,Wei Zhang,Harri Mustonen,Zhiyong Lai,Yang Yang,Chao Wang,Shan Wang,Yancheng Cui,Yingjiang Ye,Zhanlong Shen,Pauli Puolakkainen

doi:10.21147/j.issn.1000-9604.2020.01.09

Abstract

ObjectiveRecent studies have shown that tumor-associated macrophages (TAMs) play an important role in cancer invasion and metastasis. Our previous studies have reported that TAMs promote the invasion and metastasis of gastric cancer (GC) cells through the Kindlin-2 pathway. However, the mechanism needs to be clarified.MethodsTHP-1 monocytes were induced by PMA/interleukin (IL)-4/IL-13 to establish an efficient TAM model in vitro and M2 macrophages were isolated via flow cytometry. A dual luciferase reporter system and chromatin immunoprecipitation (ChIP) assay were used to investigate the mechanism of transforming growth factor β2 (TGFβ2) regulating Kindlin-2 expression. Immunohistochemistry was used to study the relationships among TAM infiltration in human GC tissues, Kindlin-2 protein expression, clinicopathological parameters and prognosis in human GC tissues. A nude mouse oncogenesis model was used to verify the invasion and metastasis mechanisms in vivo. ResultsWe found that Kindlin-2 expression was upregulated at both mRNA and protein levels in GC cells cocultured with TAMs, associated with higher invasion rate. Kindlin-2 knockdown reduced the invasion rate of GC cells under coculture condition. TGFβ2 secreted by TAMs regulated the expression of Kindlin-2 through the transcription factor NF-кB. TAMs thus participated in the progression of GC through the TGFβ2/NF-κB/Kindlin-2 axis. Kindlin-2 expression and TAM infiltration were significantly positively correlated with TNM stage, and patients with high Kindlin-2 expression had significantly poorer overall survival than patients with low Kindlin-2 expression. Furthermore, Kindlin-2 promoted the invasion of GC cells in vivo. ConclusionsThis study elucidates the mechanism of TAMs participating in GC cell invasion and metastasis through the TGFβ2/NF-κB/Kindlin-2 axis, providing a possibility for new treatment options and approaches.

Highlights

Gastric cancer (GC) is the fifth most frequently diagnosed cancer and the third most lethal cancer worldwide [1]
THP-1 monocytes were differentiated into M1 macrophages with 6 h PMA stimulation followed by lipopolysaccharide (LPS) + interferon (IFN)-γ treatment for 18 h, while M2 macrophages were collected after stimulation with PMA for 6 h followed by interleukin (IL)4 + IL-13 treatment for 18 h
We examined the Kindlin-2 mRNA expression and the invasive ability of GC cells in two groups: a Tumor associated macrophages (TAMs)/GC coculture group and a conventional GC cell-only group

Summary

Introduction

Gastric cancer (GC) is the fifth most frequently diagnosed cancer and the third most lethal cancer worldwide [1]. The molecular mechanism of GC invasion and metastasis remains unclear. The M2 phenotype of macrophages may regulate the invasion and metastasis of various tumors [8,9,10]; the mechanisms involved in this process remain unclear. Our previous study found that Kindlin-2 protein expression was positively correlated with the infiltration depth and lymph node metastasis of GC at the mRNA and protein levels, but negatively correlated with prognosis [13]. We found that the invasive ability of GC cells enhanced by TAMs can be inhibited by interfering with Kindlin-2 expression. We speculate that Kindlin-2 may play an important role in TAM-mediated process of GC invasion and metastasis and that this mechanism is worth studying

Methods

Results

Conclusion