RARB associated with MSI, affects progression and prognosis of gastric cancer

Abstract

Microsatellite instability (MSI) has been widely acknowledged as an important factor regulating tumor intrinsic biological behavior and affecting the survival of gastric cancer patients. Here, we firstly identified the RARB as a gene associated with MSI gastric cancer. RARB was downregulated in human gastric cancer tissues compared to paired paracancerous tissues, Knockdown of RARB accelerated the proliferation, invasion and migration of cancer cells in vitro. Mechanismly, RARB knockdown promoted epithelial-mesenchymal transition (EMT) process of gastric cancer. However, RARB^Low patients exhibited better survival compared to RARB^High patients. Further study revealed that RARB expression was inversely correlated with MSI status and immune infiltrates in vivo. Thus, RARB may be a potential target for the treatment of gastric cancer.

Keywords: Gastric cancer; MSI; RARB; Tumor immune microenvironment.

Fig. 1

RARB was identified as an important MSI associated gene (A, B): Heatmap of mantis score and sensors score; (C, D): VENN diagram shows 24 downregulated genes and 1 upregulated gene associated with MSI; (E, F,G): GO pathway analysis in terms of biological process, cellular component and molecular function; (H): Activity of Candidate Genes in Cancer-Related Pathways. (I): RARB and AR were the main genes participating in the cancer pathway

Fig. 2

The Clinical relevance of RARB. (A, B, C, D): Relationship between the expression of RARB and MMR system-related proteins; E: Relationship between RARB expression and MSI status in gastric cancer patients; (F, G, H, I, J, K, L, M, N): Relationship between RARB expression and clinical characteristics of RARB. *, P < 0.05;**, P < 0.01;***, P < 0.001

Fig. 3

Knockdown of RARB accelerated the proliferation, invasion and migration of cancer cells in vitro. A: Representative immunohistochemical images of RARB expression in normal gastric tissues and gastric cancer tissues; B: The mRNA level of RARB in gastric cancer cells detected by qRT-PCR; (C, D): The expression level of RARB after knockdown by siRNA in two gastric cancer cells, MKN-7 and HGC-27; (E, F): The CCK-8 assay revealed the growth trend of gastric cancer cells after RARB knockdown; (G): The effect of RARB knockdown on the proliferation of gastric cancer cells via colony formation assay; (H): The cell migration and invasion capacity of gastric cancer cells detected by transwell assay after RARB knockdown. *,P < 0.05;**,P < 0.01;***,P < 0.001.

Fig. 4

RARB knockdown promoted epithelial-mesenchymal transition (EMT) process of gastric cancer. (A, B, C): GESA analysis of relationship between RARB and advanced cancer process, lymphatic vessels invasion, and EMT; (D): Effect of knockdown of RARB on EMT makers’ expression in gastric cancer cells by Western blot. *, P < 0.05;**, P < 0.01;***, P < 0.001

Fig. 5

RARB controls different transcriptional programs in gastric cancer. A: DEGs histogram; B: DEGs volcano plot; C: DEGs heatmap; D: GO enrichment analysis; E: KEGG enrichment analysis

Fig. 6

RARB expression is inversely correlated with survival of gastric cancer patients. A: Kaplan-Meier analysis of disease free survival for gastric cancer patients with high (n = 192) and low (n = 192) RARB expression. B: Kaplan-Meier analysis of overall survival for gastric cancer patients with high (n = 192) and low (n = 192) RARB expression; Representative immunohistochemical images of CD3, CD8 and CD68 expression in RARB RARB^High and RARB^Low gastric cancer tissues