The Expression Of Id1 And Abstraction Of It's Interaction Protein In Prostate Cancer

Background: It has been proved recently that over expression of Idl protein (inhibitor of differentiation or inhibitor of DNA binding) is related to the growth and malignancy of tumors. Some studies have demonstrated that over expression of Idl occurs in many malignant tumors. Prostate cancer is one of the most common malignancy tumor in men. Chetcuti A et al (2001) first identified differentially expressed Idl gene in human organ-confined prostate cancer by gene expression array. Then over expression of Idl was further detected in human prostate cancer specimens by immunohistochemical study and in situ hybridization. But there is little known about the relationship to clinical data such as pathology class (Gleason grades) and prognosis. Furthermore, interaction protein of Idl is not clear.Objective: This study was to explore the expression of Idl mRNA and protein in human prostate cancer , and the correlation between Idl and Gleason grades, as well as prognosis, and abstraction of the interaction protein of Idl.Methods: By immumofluorescence method, the expression of Idl protein was detected in paraffin-embedded specimens of 43 prostate cancer (PC) cases, 12 benign prostatic hyperplasia (BPH) cases and two normal prostates. The quantity of Idl mRNA relative to P-actin was detected by SYBR Green I-based Real Time RT-PCR in prostatectomy or biopsy samples: 2 human normal prostates, 18 BPH and 38 prostate cancer samples. The relationship between Idl and some clinical pathological parameters, such as Gleason grades, prostate specific antigen (PSA) and clinical stage, was further analyzed. By prokaryotic expression, Idl protein was gained and identified by Western blotting, then the interaction protein of Idl can be preyed by ProFound Pull-Down PolyHis Protein Interaction technique.Results: No Idl staining was found in normal prostate tissues. There was negative to weak Idl protein staining in BPH (6/12). In contrast, Idl protein was obviously up-regulated in all of human prostate cancer samples (43/43). Most of prostate cancer tissues showed moderate to high positive expression, which was significantly higher than that of BPH (P<0.01). Furthermore, Idl protein expression was direct ratio with Gleason grades (^=0.63, P<0.01). The mean quantity of Idl mRNA relative to P-actin was obviously higher than that in BPH (P< 0.001). The expression of Idl mRNA was positively linear correlation with Gleason grade in prostate cancer group (r=0.9995, P<0.05). After therapeutic prostatectomy one to two years, the probability of infiltration and relapse was obviously higher in the patients whose Idl protein and mRNA expression were markedly up-regulation. Idl protein was gained and identified by SDS-PAGE and Western blotting. Conclusions: Over expression of Idl is in prostate cancer and the level of Idl expression is positive related to Gleason grade, suggesting that Idl is associated with prostate tumor malignancy. The expression of Idl mRNA is significantly increased in prostate cancer, and it also reflects the progression of prostate cancer on the level of transcription. Idl protein was obtained by prokaryotic expression, providing the foundation to find the Idl interaction protein. In conclusion, Idl might become a new marker of prostate cancer for diagnosis and prognosis.