Overexpression of L1 cell adhesion molecule correlates with aggressive tumor progression of patients with breast cancer and promotes motility of breast cancer cells.

BACKGROUND AND PURPOSE L1 cell adhesion molecule (L1CAM) has been observed to be aberrantly expressed and implicated in progression of several types of human cancers. However, its roles in breast cancer have not been fully elucidated. In this study, we aimed to investigate the clinical significance of L1CAM in human breast cancer and to validate whether it participates in cancer cell migration and invasion. METHODS Immunohistochemical analysis of 100 breast cancer and matched non-cancerous breast tissues was performed to detect the expression and sub-cellular localization of L1CAM protein. Its associations with clinicopathological characteristics of breast cancer patients were statistically analyzed and its phenotypic effects were also evaluated in vitro. RESULTS Of the 100 breast cancer patients, 89 (89.0%) were positive for L1CAM immunostaining localized in the membrane of cancer cells. The immunoreactive scores of L1CAM protein in breast cancer tissues were significantly higher than those in matched non-cancerous breast tissues (P<0.05). Chi-Square analysis showed the significant associations between L1CAM overexpression and high tumor stage (P=0.01), advanced tumor grade (P=0.03), positive lymph node metastasis (P=0.01) and tumor recurrence (P=0.01) in breast cancer patients. Moreover, we found that RNA interference-mediated knockdown of L1CAM could inhibit the migration and invasion abilities of breast cancer cells in vitro. CONCLUSIONS Our results suggest that the overexpression of L1CAM may be related to several established markers of poor prognosis in breast cancer patients. L1CAM might be a potential therapeutic target against metastatic breast cancer.