Combination of cetuximab with met inhibitor in control of cetuximab-resistant oral squamous cell carcinoma.

To investigate the underlying molecular mechanisms contributing to oral squamous cell carcinoma (OSCC) cell resistance to the epidermal growth factor receptor (EGFR) inhibitor. OSCC cell lines HSC-2 and HSC-3 were assessed for drug treatment, cell viability, and gene expression and the online gene expression in OSCC tissues was analyzed for association with OSCC prognosis. HSC-2 and HSC-3 cells expressed high EGFR levels, but hepatocyte growth factor (HGF) treatment induced cetuximab resistance, whereas the Met inhibitor PHA-665752 as well as Met siRNA was able to restore OSCC cell sensitivity to cetuximab. HGF treatment induced tumor cells to express p-Akt and p-ERK1/2. In contrast, the activity of Akt and ERK1/2 was suppressed by treatment with PHA-665752, Met siRNA, or their combination. Furthermore, Met was highly expressed in OSCC tissues and associated with a poor patient survival, while Met/HGF-activated Akt also was associated with a poor patient survival. This study demonstrates that Met/HGF expression results in OSCC resistance to cetuximab and tumor recurrence after cetuximab therapy; thus, inhibition of Met/HGF activity could restore OSCC sensitivity to cetuximab.