title: Loss of epidermal growth factor receptor expression in oral squamous cell carcinoma is associated with invasiveness and epithelial-mesenchymal transition.
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 high-grade invasive cells was significantly downregulated compared with that of low-grade invasive cells. There was no significant antiproliferative effect in the high-grade invasive cells treated with various concentrations of cetuximab. The EMT-associated genes, N-cadherin, vimentin and Snail, were upregulated in the high-grade invasive cells. The low-grade invasive cells exhibited characteristics of typical epithelial cells, including the expression of E-cadherin and absence of the expression of N-cadherin, vimentin and Snail. Transforming growth factor-β induced low-grade invasive cells to undergo an epithelial-mesenchymal 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.
authors: Department of Oral and Maxillofacial Surgery, Division of Cancer Medicine, Kanazawa University Graduate School of Medical Science, Kanazawa, Ishikawa 920-8640, Japan.
authors: Iyo
authors: I
authors: Kimura
authors: Department of Oral and Maxillofacial Surgery, Division of Cancer Medicine, Kanazawa University Graduate School of Medical Science, Kanazawa, Ishikawa 920-8640, Japan.
authors: Hiroko
authors: H
authors: Kitahara
authors: Department of Oral and Maxillofacial Surgery, Division of Cancer Medicine, Kanazawa University Graduate School of Medical Science, Kanazawa, Ishikawa 920-8640, Japan.
authors: Kazuhiro
authors: K
authors: Ooi
authors: Department of Oral and Maxillofacial Surgery, Division of Cancer Medicine, Kanazawa University Graduate School of Medical Science, Kanazawa, Ishikawa 920-8640, Japan.
authors: Koroku
authors: K
authors: Kato
authors: Department of Oral and Maxillofacial Surgery, Division of Cancer Medicine, Kanazawa University Graduate School of Medical Science, Kanazawa, Ishikawa 920-8640, Japan.
authors: Natuyo
authors: N
authors: Noguchi
authors: Department of Oral and Maxillofacial Surgery, Division of Cancer Medicine, Kanazawa University Graduate School of Medical Science, Kanazawa, Ishikawa 920-8640, Japan.
authors: Kunio
authors: K
authors: Yoshizawa
authors: Department of Oral and Maxillofacial Surgery, Division of Cancer Medicine, Kanazawa University Graduate School of Medical Science, Kanazawa, Ishikawa 920-8640, Japan.
authors: Hiroyuki
authors: H
authors: Nakamura
authors: Department of Oral and Maxillofacial Surgery, Division of Cancer Medicine, Kanazawa University Graduate School of Medical Science, Kanazawa, Ishikawa 920-8640, Japan.
authors: Shuichi
authors: S
authors: Kawashiri
keywords: cetuximab; epidermal growth factor receptor; epithelial-mesenchymal transition; invasiveness; oral squamous cell carcinoma