Background: Prostate cancer (PC) as a kind of malignant tumor, causes the most death of cancer among males. Successful curing of PC greatly relies on its diagnose in the early stage. Engrailed-2 (EN2), which has been confirmed being existed in the high level in the urine of PC patients. In this study, we determine if there were differences in the staining patterns and expression level of EN2 in benign prostatic hyperplasia (BPH) and PC.
Methods: Immunohistochemical and RT-PCR analysis of the expression of EN2 was conducted in 25 PC and 25 BPH cases. EN2 monoclonal antibody against EN2 helix 3 was developed and its specificity was identified. The subcellular localization of endogenic and exogenous EN2 in three PC cell lines (LNCap, PC3, and DU145) was detected by immunofluorescence. Correlation among clinical indicators and EN2 immunohistochemical scores of these 25 PC and 25 BPH cases were analyzed and two representative PC cases with different EN2 expression were used to vividly illustrate the correlation between EN2 expression and PC clinical stage.
Results: The results of western-blotting (WB) and immunofluorescence showed homemade EN2 monoclonal antibody could specifically bind endogenic and ectogenic EN2 protein in three different PC cell lines. Results of immunofluorescence showed the endogenic EN2 was generally expressed in the cytoplasm and ectogenic EN2 has mostly existed in the nucleus of three PC cell lines. Immunohistochemical staining of EN2 in PC was extremely higher than in BPH confirmed by RT-PCR. The staining areas were mostly nucleus and cytoplasm in BPH tissues but cytomembrane in PC tissues. The expression level of EN2 was positively correlated with the PC clinical stage.
Conclusion: The EN2 monoclonal antibody we made could be used in immunohistochemistry to display the expression pattern of EN2 in BPH and PC. The staining patterns and expression level of EN2 in BPH and PC are different.