Plasma long noncoding RNA protected by exosomes as a potential stable biomarker for gastric cancer.

Long intergenic non-protein-coding RNA 152 (LINC00152) is one of the long noncoding RNAs (lncRNAs) abnormally expressed in gastric cancer tissues. However, its value in the diagnosis of gastric cancer is unclear. The aim of this study is to evaluate the clinical significance of plasma LINC00152 as a biomarker in the screening of gastric cancer and to explore the possible mechanism underling its stable existence in blood. We analyzed the levels of plasma LINC00152 in patients with gastric cancer and gastric epithelial dysplasia and healthy controls using quantitative reverse transcription polymerase chain reaction and then confirmed by sequencing. We also compared its levels in paired preoperative and postoperative plasma samples. In addition, we compared the levels of LINC00152 in plasma and in exosomes, which were extracted from the same plasma and confirmed by transmission electron microscopy. The levels of plasma LINC00152 were significantly elevated in gastric cancer patients compared with healthy controls. The sensitivity and specificity of plasma LINC00152 in the diagnosis of gastric cancer were 48.1 and 85.2%, respectively. There were no significant differences of LINC00152 levels between gastric epithelial dysplasia patients and healthy controls. LINC00152 levels in preoperative plasma samples were lower than those in postoperative ones. There were also no differences between LINC00152 levels in plasma and in exosomes. All these results suggested that LINC00152 can be detected in plasma, and one of the possible mechanisms of its stable existence in blood was protected by exosomes. It has the possibility to be applied in gastric cancer diagnosis as a novel blood-based biomarker.