Background and Aims: Lymph node metastasis is a key factor affecting the prognosis of patients with colorectal cancer (CRC). Voltage gated sodium ion channels (Nav) are highly expressed in a variety of tumors and closely related to tumor metastasis. Therefore, this study was conducted to investigate the expressions of different Nav subtypes in CRC tissue, and relationship between the Nav expressions and lymph node metastasis as well as invasiveness of CRC. 
Methods: The surgical specimens of tumor tissue and adjacent tissues from 100 patients with first-onset of CRC were collected. After identification by HE staining, the expressions of different Nav subtypes in the two types of tissues were detected by qRT-PCR. The associations of different Nav subtypes with lymph node metastasis, vascular infiltration as well as neural invasion in CRC patients were analyzed. The difference in the expressions of relevant Navs in non-metastatic lymph nodes and metastatic lymph nodes was detected by immunohistochemical staining.
Results: A number of Nav subtypes were highly expressed in CRC tissue, especially the Nav1.1, Nav1.5, Nav1.6 and Nav1.8. Among these Nav subtypes, the expressions of Nav1.1 and Nav1.6 were significantly increased in tumor tissues from patients with positive lymph nodes, and the expression of Nav1.6 was significantly increased in tumor tissues from patients with vascular infiltration (all P<0.05). The results of correlation analysis showed that the expressions of Nav1.1 and Nav1.6 were positively correlated with lymph node metastasis (r=0.272, P=0.006; r=0.234, P=0.019), the expression of Nav1.6 was positively correlated with vascular infiltration (r=0.341, P=0.001) and the expression of Nav1.6 was positively correlated with neural invasion (r=0.330, P=0.001). The results of immunohistochemical staining showed that Nav1.6 was highly expressed in positive lymph nodes, while low expression of Nav1.1 was found in both positive and negative lymph nodes.
Conclusion: Various Nav subtypes are abnormally expressed in CRC tissue, among them, Nav1.1 and Nav1.6 are possibly the potential markers for lymph node metastasis in CRC, and Nav1.6 may be closely related to the invasiveness of CRC cells.