Killer cell lectin-like receptor G2 facilitates aggressive phenotypes of gastric cancer cells via dual activation of the ERK1/2 and JAK/STAT pathways.

BACKGROUND: Advanced gastric cancer (GC) has a poor prognosis. This study aimed to identify novel GC-related genes as potential therapeutic targets.

METHODS: Killer cell lectin-like receptor G2 (KLRG2) was identified as a candidate gene by transcriptome analysis of metastatic GC tissues. Small interfering RNA-mediated KLRG2 knockdown in human GC cell lines was used to investigate KLRG2 involvement in signaling pathways and functional behaviors in vitro and in vivo. Clinicopathological data were analyzed in patients stratified according to tumor KLRG2 mRNA expression.

RESULTS: KLRG2 knockdown in GC cells decreased cell proliferation, migration, and invasion; caused cell cycle arrest in G2 /M phase; induced apoptosis via caspase activation; suppressed JAK/STAT and MAPK-ERK1/2 pathway activities; and upregulated p53 and p38 MAPK activities. In mouse xenograft models of peritoneal metastasis, the number and weight of disseminated GC nodules were decreased by KLRG2 knockdown. High tumor levels of KLRG2 mRNA were significantly associated with lower 5-year overall survival (OS) and relapse-free survival (RFS) rates in patients with Stage I-III GC (5-year OS rate: 64.4% vs. 80.0%, P = 0.009; 5-year RFS rate: 62.8% vs. 78.1%, P = 0.030).

CONCLUSIONS: KLRG2 knockdown attenuated the malignant phenotypes of GC cells via downregulation of JAK/STAT and MAPK-ERK1/2 pathway activity and upregulation of p38 MAPK and p53. Targeted suppression of KLRG2 may serve as a new treatment approach for GC.