[Nuclear translocation of epidermal growth factor receptor and its relation to clinicopathological factors in oral squamous cell carcinomas].

The epidermal growth factor receptor (EGFR) is one of the receptor tyrosine kinases. Some EGFRs are transferred from membrane to nucleus upon ligand binding and an increase of this translocation causes high-level expression of nuclear EGFR. The high-level expression of nuclear EGFR was reported to be a poor prognostic factor in various cancers such as breast cancer, ovarian cancer, gallbladder cancer, prostate cancer and oropharyngeal cancer. Regarding oral cancers, one report indicated that nuclear EGFR is detected in oral squamous cell carcinoma (OSCC) on immunohistochemical staining, but did not mention the clinicopathological prognostic value in detail. Therefore, we investigated the expression of nuclear EGFR in OSCC cell lines and primary tumor specimens of tongue SCCs to see whether nuclear EGFR could be a useful prognostic value. We verified the expression level of nuclear EGFR in OSCC cell lines and observed an increase in the amount of nuclear EGFR upon EGF stimulation with the expression level reaching its peak after 15 minutes. Nuclear EGFR positive tumors were found in 23 patients (28.0%) with tongue SCCs. However, we could not find any correlation between clinicopathological factors and the expression of nuclear EGFR in patients with tongue SCCs.