Correlation between connexin 43 expression in circulating tumor cells and biological characteristics of breast cancer

BACKGROUND: Connexin 43 (Cx43) has been closely linked to the occurrence and progression of breast cancer. Distant metastasis of breast cancer is aided by the epithelial-mesenchymal transition of circulating tumor cells (CTCs). However, the impact of Cx43 expression on CTCs and the extent of its role in the disease remain unclear. METHODS: We determined CTCs in 156 patients, who had breast cancer with a disease course of two or more years. We also measured the expression of Cx43 in the CTCs. The CTCs were detected in the blood of 139 of these patients. These 139 patients were divided into two groups: the Cx43 group and the non-Cx43 group based on their Cx43 expression. RESULTS: Overall, Cx43 expression was found in 83 of the 139 patients (59.7%, 83/139 cases). The two groups significantly differed in terms of the number of mixed biphenotypic type CTCs and the total number of CTCs (P < 0.05). There were significant correlations between Cx43 expression and Ki67 expression, tumor size, lymph node metastasis, and TNM stage (P < 0.05 for all). The data suggested that patients with Cx43 expression had a higher risk of distant metastasis and had later-stage disease. The difference in Cx43 expression between patients with and without epidermal growth factor receptor 2 (Her2) overexpression was statistically significant (P < 0.05). The difference in disease-free survival (DFS) between the two groups was statistically significant (P = 0.03), and the Cx43 group had a shorter duration of DFS. Univariate Cox regression analysis revealed that Cx43 expression, Her2 expression, and tumor size were significantly correlated with DFS (P = 0.03, 0.0023, and 0.01, respectively). CONCLUSION: Cx43 expression in the CTCs of patients with breast cancer is a cancer-promoting factor.