Expression of voltage-gated sodium channel Nav1.5 in non-metastatic colon cancer and its associations with estrogen receptor (ER)-β expression and clinical outcomes.

BACKGROUND: Voltage-gated sodium channel 1.5 (Nav1.5) potentially promotes the migratory and invasive behaviors of colon cancer cells. Hitherto, the prognostic significance of Nav1.5 expression remains undetermined. The present study aimed to explore the associations of Nav1.5 expression with clinical outcomes and estrogen receptor-β (ER-β) expression in non-metastatic colon cancer patients receiving radical resection.

METHODS: A total of 269 consecutive patients with pathologically confirmed stages I-III colon cancer who underwent radical resection were selected. Nav1.5 and ER-β expression was detected by using immunohistochemistry (IHC) on tissue microarray constructed from paraffin-embedded specimens. IHC score was determined according to the percentage and intensity of positively stained cells. Statistical analysis was performed with the X-tile method, k coefficient, Chi square test or Fisher's exact test, logistic regression, log-rank test, and Cox proportional hazards models.

RESULTS: We found that Nav1.5 was commonly expressed in tumor tissues with higher mean IHC score as compared with matched tumor-adjacent normal tissues (5.1 ± 3.5 vs. 3.5 ± 2.7, P < 0.001). The high expression of Nav1.5 in colon cancer tissues was associated with high preoperative carcinoembryonic antigen level [odds ratio (OR) = 2.980; 95% confidential interval (CI) 1.163-7.632; P = 0.023] and high ER-β expression (OR = 2.808; 95% CI 1.243-6.343; P = 0.013). Log-rank test results showed that high Nav1.5 expression contributed to a low 5-year disease-free survival (DFS) rate in colon cancer patients (77.2% vs. 92.1%, P = 0.048), especially in patients with high ER-β expression tumor (76.2% vs. 91.3%, P = 0.032). Analysis with Cox proportional hazards model demonstrated that high Nav1.5 expression [hazard ratio (HR) = 2.738; 95% CI 1.100-6.819; P = 0.030] and lymph node metastasis (HR = 2.633; 95% CI 1.632-4.248; P < 0.001) were prognostic factors for unfavorable DFS in colon cancer patients.

CONCLUSIONS: High expression of Nav1.5 was associated with high expression of ER-β and indicated unfavorable oncologic prognosis in patients with non-metastatic colon cancer.