Leucine-rich repeat neuronal protein-1 suppresses apoptosis of gastric cancer cells through regulation of Fas/FasL.

Gastric cancer (GC) is a common cause of cancer-related death worldwide. As a result of the lack of reliable diagnostic or prognostic biomarkers for GC, patient prognosis is still poor. Therefore, there is an urgent need for studies examining the underlying pathogenesis of GC in order to find effective biomarkers. LRRN1 (leucine-rich repeat neuronal protein-1) is a type I transmembrane protein that plays an important role in the process of nerve development and regeneration. However, its role in cancer, especially in GC, remains unclear. In the present study, we found that LRRN1 expression is upregulated in GC tissues and that high LRRN1 expression is associated with poor prognosis. siRNA and shRNA-mediated knockdowns of LRRN1 expression promoted GC cell apoptosis and activation of the Fas/FasL pathway. LRRN1 knockdown also resulted in upregulation of JUN, a subunit of the transcription factor AP-1 (activator protein-1). This suggests that LRRN1 suppresses GC cell apoptosis by downregulating AP-1, resulting in inhibition of the Fas/FasL pathway. These results confirm that LRRN1 plays a significant role in GC pathogenesis. Moreover, LRRN1 may be a potential prognostic biomarker and therapeutic target for GC.