SC1, an immunoglobulin-superfamily cell adhesion molecule, is involved in the brain metastatic activity of lung cancer cells.

SC1 is a cell adhesion molecule that belongs to the immunoglobulin superfamily; this molecule was initially purified from the chick embryonic nervous system and was reported to exhibit homophilic adhesion activity. SC1 is transiently expressed in various organs during development and has been identified in numerous neoplastic tissues, including lung cancer and colorectal carcinomas. The present study focused on the encephalic metastasis of lung cancer cells with respect to the potential function of SC1, as this molecule is known to be consistently expressed in the central nervous system as well as lung cancers. SC1 complementary DNA was introduced into A549 cells, a human lung cancer-derived cell line. The stable overexpression of the SC1 protein in A549 cells was demonstrated to enhance the self-aggregation of the cells. In addition, the SC1 transfectants enhanced the metastatic and invasive potential to the encephalic parenchyma following implantation into nude mice. In conclusion, the results of the present study demonstrated that cell adhesion due interactions between SC1 on brain tissue and SC1 on lung cancer cells was involved in the malignant aspects of lung cancer, including invasion and metastasis to the brain.