RAI3 is overexpressed in gastric adenocarcinoma but unrelated to prognosis

PURPOSE: Retinoic acid-induced gene 3 (RAI3) has been associated with tumorigeneses in several cancer types. To clarify the clinical significance of RAI3 expression in premalignant and malignant gastric epithelium, RAI3 protein expression was assessed by immunohistochemistry on tissue microarrays (TMAs) containing 140 gastric dysplasia and 230 GC samples.

FINDINGS: RAI3 protein expression was predominantly localized in the cell membrane and was detectable in low intensities in most of the benign gastric tissue samples. RAI3 expression was found in increased intensities in premalignant and malignant epithelium relative to non-malignant gastric epithelium (P < 0.0001). High RAI3 expression was found in 66.2% of interpretable gastric adenocarcinomas and was associated with advanced pathological tumor stage (P = 0.0014) and positive lymph node status (P = 0.0137) but was unrelated to overall survival of patients (P = 0.3743).

CONCLUSION: The deregulation of RAI3 in premalignant and gastric epithelium suggests a relevant role of RAI3 during gastric carcinogenesis. Additionally, RAI3 overexpression defines a subset of GCs with aggressive tumor features. However, since RAI3 expression was not associated with clinical outcome of patients, RAI3 cannot be considered as a prognostic biomarker in patients with GCs.