DJ-1 may contribute to metastasis of non-small cell lung cancer

Lung cancer is a leading cause of cancer-related death, about 40% human non-small cell lung cancer (NSCLC) patients showed lymph node involvements. However, the precise mechanism for the metastasis is still not fully understood. This study was to analyze the potential molecular mechanism for lung cancer metastasis. In the current study, proteomics analysis by two-dimensional electrophoresis (2-DE) was performed first to identify the differentially expressed protein between the higher metastasis lung adenocarcinoma cell line Anip973 and the lower metastasis lung adenocarcinoma cell line AGZY83-a. We confirmed the result by RT-PCR, immunoblotting and immunocytochemistry analyses in these two cell lines. Then we examined the expression of the differentially expressed protein in tumor tissues of NSCLC patients by immunoblotting and immunohistochemistry analyses. Using 2-DE analysis, we have identified DJ-1 was expressed higher in the higher metastasis Anip973 compared to the parental cell line AGZY83-a, that was confirmed by RT-PCR, immunoblotting and immunocytochemistry analyses. In NSCLC patients' tumor tissues study, immunoblotting data showed that, DJ-1 expression level was significantly higher in 72.2% (13/18) of NSCLC tissue samples compared to that in paired normal lung tissues (P = 0.044). Immunohistochemistry analysis demonstrated increased DJ-1 expression in 85 NSCLC tumor tissue samples compared with 7 normal lung tissue samples (P = 0.044). DJ-1 expression was also found to be significantly correlated with cancer lymphatic metastasis (P = 0.039). DJ-1 might contribute to the metastasis of NSCLC.