Expression and its Clinical Significance of NOK, EGFR in NSCLC

Background and objective NOK (Novel Oncogene with Kinase-domain) is a newly identified receptor protein-tyrosine kinases (RPTKs) subfamily, which possesses strong oncogenic potential including enhancing cell transformation, tumorigenesis, invasion and metastasis. However, NOK protein lacks extracellular domain, and how the NOK is activated by the membrane receptor and the expression of NOK in non small cell lung cancer (NSCLC) are not clear. Our aim of this study was to investigate the expressions of NOK, EGFR proteins in NSCLC. Methods The expression rates of NOK, EGFR proteins in 155 cases with NSCLC was deteced by immunohistochemical stain; The clinical correlations between two proteins were analyzed by statistics. Results The NOK positive expression was mainly located in cytoplasm and EGFR was mainly located in the plasma membrane and cytoplasm. NOK, EGFR proteins were high expressed in NSCLC and there were extremely differences comparing the expression of NOK, EGFR proteins in squamous cell lung cancer, lung adenocarcinoma with those in corresponding normal tissue respectively (P < 0.001); and there were no significant differences between the two kinds of the cancers for their comparison of NOK, EGFR expression (P=0.099; P=0.23); however, there were significant differences for NOK and EGFR expression among histological grades and TNM stages in squamous cell lung cancers, lung adenocarcinoma (P < 0.01). There were correlation between positive and intensity of NOK and EGFR expression in whatever total NSCLC or squamous cell lung cancer or lung adenocarcinoma (P < 0.001), while the correlation coefficients(rs) were 0742, 0.722, 0.756 respectively. Conclusion The NOK proteins are highly expressed in the NSCLC, and the expression rates of NOK proteins are correlated with the cancers’ histological grades and TNM stages, which may be concern with tumorgenesis and progression; the positive expression rate and intensity of NOK protein correlate well with the expression of EGFR protein in NSCLC, which the activation of NOK probably owe to EGFR activation, all that would provide evidence for further study on the effective mechanism of NOK in the tumorigenesis or tumor progression.