TREM1 promotes cancer associated malignant phenotype through activated MAPK signaling pathway and predicts poor prognosis in gastric cancer

Abstract

Background: CD molecules plays a vital role in gastric cancer (GC). We used bioinformatics analysis methods to develop prognosis related CD molecules risk signature; On the other hand, we used the experiments to further explore the function and mechanism of differentially expressed prognostic CD molecules (TREM1) in GC.

Methods: Kaplan-Meier survival and univariate Cox regression analysis were used to evaluate the overall survival of CD molecule genes in gastric cancer. ROC curve and Kaplan-Meier curves were used to analyze the predictive value of CD molecule related genes risk signature by "survival and timeROC" R packages. GSEA, and Cibersortx software were used to analyze the functional enrichment. Finally, we verified the function and mechanism of TREM1 in GC by gene silencing and MAPK inhibitor (SB203580) in vitro and vivo.

Results: A total of 41 prognosis related risk factors in gastric cancer were identified based on CD molecules, including TREM1 and ect. The high-risk patients had higher risk score and shorter survival time. ROC curves revealed that this risk signature accurately predicted survival times of gastric cancer patients at the 1-, 2-, 3-, 4- and 5-year. The frequency of T cells follicular helper and NK cells activated were added in low-risk group. Next, differentially expressed prognostic CD molecules analysis revealed that TREM1 was identified as key genes in GC progression based on TCGA and GES158662 and GSE15459 datasets of GC. In vitro experiments, TREM1 silencing significantly inhibited GC cell proliferation and migration, induced cell apoptosis. GSEA revealed that TREM1 activated cancer related signaling pathway, including MAPK signaling pathway and ect. High expression of TREM1 was related Macrophages M2 and Mast cells resting in GC tissues. Moreover, knockdown of TREM1 inhibited tumor growth through downregulated MAPK signaling pathway in vivo.

Conclusion: These results identified that CD molecule related genes as a novel prognostic and diagnostic biomarker in gastric cancer. TREM1 acts as an oncogene role in GC by activated MAPK signaling pathway.

Keywords: CD molecules; Gastric cancer; MAPK signaling pathway; Prognosis; TREM1.

Fig. 1

Univariate Cox regression analyses of CD molecules influencing overall survival in gastric cancer.

Fig. 2

The landscape of TME. (A) The heatmap of tumor infiltrating immune cells expression. Red indicates high risk group; Blue indicates low risk group. (B) Differentially analysis of 22 tumor infiltrating immune cells by Wilcoxon test analysis. (C) The expression of immune checkpoint molecules in low- and high -risk groups of gastric cancer patients. (*P < 0.05; **P < 0.01; ***P < 0.001).

Fig. 3

The expression and CNA of CD molecules genes in GC. (A) The differentially expressed CD molecule genes in tumor compared with normal group based on the GC-TCGA dataset, Red font indicates upregulated genes, Blue font indicates downregulated genes (*P < 0.05; **P < 0.01; ***P < 0.001). (B) copy number alteration frequency of CD molecule genes in gastric cancer. (C) Veen diagram shows total of 2 differentially expressed CD molecule genes in between GC tissue with normal tissues base on TCGA and GSE158662 datasets. (D) The mRNA expression of TREM1 and CD36 was detected in GES-1, AGS, HGC27 cells lines (*P < 0.05; ***P < 0.001).

Fig. 4

Effects of TREM1 on the proliferation, migration and apoptosis of AGS and HGC27 cells. (A) TREM1 expression was analyzed by RT-qPCR assay. (B) CCK-8 assay detected the AGS and HGC27 cells proliferation. (C) Colon formation assay was used to detected cell growth number of AGS and HGC27 cells. (D) colony number was calculated. (E) Flow cytometry assay was used to detect the apoptosis of AGS and HGC27 cell lines. (F) Cell apoptosis rate was calculated. (G) Transwell assay was performed to explore the migration of AGS and HGC27 cell lines. (H) Cell migration number were calculated. Data are represented as mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001.

Fig. 5

Gene set enrichment analysis. (A) The HALLMARK pathway enrichment of high/low expression of TREM1 in gastric cancer. (B) The KEGG pathway enrichment of high/low expression of TREM1 in gastric cancer.

Fig. 6

TREM1 silencing inhibited tumor growth and tumor volume by downregulated MAPK signaling pathway. (A and B) Tumor growth of TREM1 shRNA, Control, TREM1 shRNA + SB203580. (C) Tumor weight was measured. (D) Tumor volume was measured at 0, 3, 5, 7, 10, 13, 15, 18, 21 days. Data are presented as mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001.