Abstract

BACKGROUND
Although it was suggested that constitutive extracellular signal regulated kinase (ERK) activation plays a pivotal role in intracellular signal transduction related to oncogenesis, a consistent relationship between constitutive ERK activation and oncogenesis has not yet been clearly demonstrated. The purpose of this study is to evaluate the expression frequencies and pattern of phosphorylated ERK (p-ERK) in the non-small cell lung carcinoma (NSCLC) and to evaluate whether p-ERK is a useful prognostic factor.
METHODS
One hundred sixty cases of NSCLC tissue specimens were investigated by immunohistochemical staining for p-ERK. Clinicopathologic values (tumor stage, cell type, differentiation and presence of metastasis) and p-ERK expression of normal alveolar pneumocytes around NSCLC were compared with the incidence of tumor p-ERK expression.
RESULTS
Fifty-three out of 160 cases (33%) of NSCLC showed expression of p-ERK. There was no statistical correlation between the expression of p-ERK in the NSCLC neoplastic cells and the corresponding tumor stage, cell type and presence of metastasis. There was statistical significance between the expressions of p-ERK in alveolar pneumocytes around NSCLC (odds ratio: 6.130).
CONCLUSIONS
Based on these results, we suggest that p-ERK expression is not useful in predicting the prognosis of NSCLC. In regard to the theory of "field cancerization" and the phenomenon of "allele-specific loss or allele-specific mutations", the statistically significant p-ERK expression in alveolar pneumocytes around NSCLC suggests that constitutive ERK activation is involved in the early stage of NSCLC carcinogenesis rather than in proliferation, differentiation or metastasis of NSCLC.

• Keywords: Mitogen-activated protein kinase;Immunohistochemistry;Carcinoma;non-small-cell;Lung