Expression of MET and SOX2 genes in non-small cell lung carcinoma with EGFR mutation

Non-small cell lung carcinoma (NSCLC) is a leading cause of cancer-related deaths. Aberrance of the two oncogenes MET and SOX2 are frequently encountered in NSCLC. Exons 18 through 21 of the EGFR gene were screened and MET and SOX2 immunostaining was conducted to analyze the immunohistological staining of MET and SOX2 and the EGFR mutation status. One hundred and fifty tissue samples were examined including 57 squamous cell carcinomas (SCCs), 80 adenocarcinomas (ADCs), 9 adenosquamous carcinomas (ADSCs) and 4 large cell carcinomas (LCCs). The 32 NSCLCs harboring an EGFR mutation included 28 ADCs, 3 SCCs and 1 ADSC. A higher level of SOX2 expression appeared in NSCLCs without the EGFR mutation compared to those with EGFR mutation (chi(2)=9.02, P=0.0027). Of the 28 ADCs, 24 (85.7%) with an EGFR mutation showed low level of SOX2 expression. ADCs with deletion in exon 19 overexpressed MET and showed low levels of SOX2. SOX2 expression was inversely correlated to the expression of MET in NSCLC and mainly present in non-mutated NSCLC (r=-0.42, P<0.0001). There was a tendency for SOX2 to be expressed in SCCs and particularly in the part of SCC among ADSCs, whereas MET was mainly expressed in the part of ADC among ADSCs and ADCs. High level of MET and SOX2 expression were respectively demonstrated in ADCs and SCCs; MET activation was accompanied with exon 19 deletion in ADCs. EGFR and MET coordinate to drive tumorigenesis. Detection of the activation of MET and EGFR may be used for targeted drug therapy.