L1 expressed by glioma cells promotes adhesion but not migration.

L1 is an adhesion molecule of the immunoglobulin superfamily expressed by several types of cancer, including gliomas. It has been shown that L1 can act as chemoattractant to glioma cells, while the effects of L1 expressed by glioma cells themselves are unknown to date. We established a C6 rat glioma clone, conditionally expressing murine L1 under control of a tetracycline responsive promoter. In vitro experiments revealed increased adhesion on matrigel as well as increased intercellular adhesion in the presence of L1, whereas no L1-dependent effects on proliferation or migration on either matrigel or myelin were observed. In vivo experiments using transplantation into nude mouse striatum, where L1 expression by glioma cells was regulated by tetracycline via drinking water, did not show effects of L1 on tumor size or brain invasion. Our data suggest that L1 expressed on the surface of glioma cells increases cell-matrix and intercellular adhesion, but has no apparent effects on proliferation and invasion.