High expression of stratifin is a universal abnormality during the course of malignant progression of early-stage lung adenocarcinoma.

Adenocarcinoma in situ (AIS) of the lung has an extremely favorable prognosis, with a 5-year survival rate of 100%. However, early invasive adenocarcinoma (EIA) often has a fatal outcome. In this study, we compared the expression profiles of AIS with those of EIA showing lymph node metastasis or a fatal outcome, and screened the differentially expressed genes by cDNA microarray. From the genes selected, we focused on Stratifin (SFN, 14-3-3 σ), which showed significantly higher expression in EIA than in AIS. Immunohistochemistry for SFN revealed that more than 95% of EIAs were immunopositive for SFN, in comparison to only 13% of AISs (p <0.05). Interestingly, positivity was detected not only in the invasive region but also in the in situ spreading component of EIA. Functionally, SFN facilitates the cell proliferation capacity of lung adenocarcinoma. These results indicate that SFN overexpression is a universal abnormality during the stepwise progression from in situ to invasive adenocarcinoma of the lung.