Supplementary Material for: PROX1 was associated with LGR5 and Wnt signaling and contributed to poor prognosis in gastric cancer

Introduction: We investigated prospero homeobox protein-1 (PROX1) expression in gastric cancer (GC) as a prognostic marker and its relationship with LGR5 and Wnt/β-catenin activity in GC. Methods: A total of 196 cases of patients who underwent GC surgery were retrospectively collected and reviewed. PROX1, LGR5, Wnt3a, and β-catenin expression was evaluated by using immunohistochemistry. The relationship between PROX1 expression and clinicopathological features was also evaluated. Results: The PROX1 low-expression group had 105 patients (53.6%) and the high-expression group 91 patients (46.4%). For LGR5, 76 patients (38.8%) had low expression and 120 (61.2%) high expression. The PROX1 low-expression group was significantly younger (p = 0.0095), had more intestinal type (p = 0.014), and smaller tumor size (p = 0.013). The PROX1 high-expression group significantly correlated with high LGR5 expression (p < .0001) and high Wnt3a expression (p = 0.012). There were more cases of postoperative recurrence in the PROX1 high-expression group (p = 0.013). Conclusion: Our findings show that PROX1 correlates with LGR5 and Wnt3a signaling in GC and has a poor prognosis with postoperative recurrence.