LAUSR

Gastric cancer (GC) is one of the most common malignancies in the world, and the search for better markers has become one of the challenges today. It has been found that the L6 superfamily regulates the biological functions of numerous tumors, but transmembrane 4 L six family member 18 (TM4SF18) has been rarely reported. We found that TM4SF18 expression is upregulated in GC tissues and cells, which can be effectively diagnosed and dynamically monitored to assess the prognosis of GC patients. Furthermore, knockdown of TM4SF18 effectively inhibited proliferation, migration, and invasion of GC cells, and affected the epithelial‐mesenchymal transition process. TM4SF18 was found to be an independent prognostic factor for GC by univariate and multifactorial Cox analyses as well as by establishing nomogram plots. In addition, in TM4SF18 and immune correlation analysis, TM4SF18 expression levels were found to be negatively correlated with most immune cell marker genes and associated with numerous immune cells and immune pathways, resulting in less benefit from treatment with immune checkpoint inhibitors. In summary, we found that TM4SF18 is a promising GC biomarker that promotes the proliferation, migration, and invasion abilities of GC cells, and is associated with immune response.