Background
External auditory canal (EAC) squamous cell carcinoma (SCC) is classified as a rare cancer and has a poor prognosis at advanced stages. Mechanical stress has been implicated in external auditory canal squamous cell carcinoma (EACSCC), but the molecular mechanism has not been elucidated. Mechanotransduction is well-known for Yes-associated protein (YAP) signaling. When YAP is translocated to the nucleus, the L1 cell adhesion molecule (L1CAM) is activated as an effector of mechanotransduction. Core fucosylation of L1CAM by Fucosyltransferase 8 (FUT8) has been implicated in the degree of tumor malignancy, modulating cleavage of the extracellular domain of L1CAM.
Conclusion
These results suggested that L1CAM expression is increased under mechanotransduction and may possibly avoid L1CAM cleavage by FUT8 modulation.
Methods
In this study, an expression analysis of YAP, L1CAM, and FUT8 was performed by stretch assay in vitro. Immunohistochemistry was also performed in human EACSCC and normal skin specimens.
Results
The labeling index of FUT8-positive cells exhibited YAP nuclear translocation under stretch stress was significantly higher in a human SCC cell line (HSC1) than in a human keratinocyte cell line. Stretch stress significantly increased the expression levels of full-length L1CAM in HSC1 cells. Moreover, colocalization of FUT8 and L1CAM was demonstrated immunohistochemically in advanced human EACSCC tissues.