MOR1 expression in gastric cancer: a biomarker associated with poor outcome

Abstract

Background: At present, the expression of MOR1 and its function in gastric cancer remains unclear with evidence suggesting that it is to be involved in tumor progression and metastasis. The study was to assess the clinicopathologic relevance and prognostic value of MOR1 expression in gastric cancer.

Methods: Real-time quantitative RT-PCR and immunohistochemical staining were used to detect MOR1 expression in primary gastric cancerous surgical specimens and adjacent nontumorous tissues.

Results: High MOR1 expression was detected in cancerous tumor compared with their adjacent nontumorous tissues. In addition, the chi-square test revealed that high MOR1 expression was significantly correlated with depth of invasion (p = 0.006), lymph node metastasis (p = 0.001), distant metastasis (p = 0.017), and TNM staging (p = 0.027). Moreover, Kaplan-Meier analysis revealed a significant association between MOR1 expression and overall survival. High expression of MOR1 was identified as an independent and significant predictor gene of reduced postoperative survival.

Conclusion: We conclude that MOR1 expression may be a useful biomarker for better prediction of the clinical outcome and management of gastric cancer patients.

Keywords: MOR1; gastric cancer; metastasis; prognosis.

Figure 1

Immunohistochemical staining of MOR1 expression in gastric cancer MOR1 expression was stained in the cytoplasm or membranous of cells. (a) Negative control; (b) Weakly positive staining for MOR1, ×400; (c) Moderately positive staining for MOR1, ×400; (d) Strongly positive staining for MOR1, ×400.

Figure 2

Real‐time quantitative RT‐PCR analysis of MOR1 expression in gastric cancer surgical specimens. The relative mRNA expression of MOR1 was significantly lower in 30 of 46 (65.0%) gastric cancer tissues compared with the corresponding nontumorous tissues. (MOR1/GAPDH; n = 46; p = 0.03)

Figure 3

Kaplan–Meier survival curves for postoperational gastric cancer patients. (a) OS curves stratified by MOR1 expression in gastric cancer tissues (low, high expression). (b) Strata based on stage (stage I–II, III–IV); (c) Strata based on lymph node status (negative, positive); (d) Strata based on lymph node status (negative, positive).