Loss of epidermal growth factor receptor expression in oral squamous cell carcinoma is associated with invasiveness and epithelial-mesenchymal transition

Author：

Publisher： Spandidos Publications

E-ISSN： 1792-1082|11|1|201-207

ISSN： 1792-1074

Source： Oncology Letters, Vol.11, Iss.1, 2016-01, pp. : 201-207

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Abstract

Inhibition of epidermal growth factor receptor (EGFR) signaling has emerged as a novel therapeutic strategy for the treatment of oral squamous cell carcinoma (OSCC). The EGFR-directed inhibitor cetuximab is currently the only approved targeted therapy for the treatment of OSCC. EGFR status may affect the patient response to cetuximab treatment. In the present study, via analysis of the immunomarker for EGFR, it was revealed that 58.3% of the total cases investigated stained positively for EGFR expression, and furthermore, that invasiveness was inversely correlated with EGFR expression. Expression levels of EGFR were quantified, and the correlation between EGFR expression and cetuximab sensitivity was investigated using three varying grades of invasive human OSCC line. EGFR expression in highgrade invasive cells was significantly downregulated compared with that of lowgrade invasive cells. There was no significant antiproliferative effect in the highgrade invasive cells treated with various concentrations of cetuximab. The EMTassociated genes, Ncadherin, vimentin and Snail, were upregulated in the highgrade invasive cells. The lowgrade invasive cells exhibited characteristics of typical epithelial cells, including the expression of Ecadherin and absence of the expression of Ncadherin, vimentin and Snail. Transforming growth factorβ induced lowgrade invasive cells to undergo an epithelialmesenchymal transition (EMT)associated gene switch, which resulted in low levels of EGFR expression. The results of the present study suggested that loss of EGFR expression in OSCC was associated with EMT, and may have functional implications with regard to tumor invasiveness and the resistance to cetuximab treatment.