USE OF PIN1 AS A MOLECULAR PROBE TO IDENTIRY PROSTATE CANCER-SPECIFIC BIOMARKERS

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The peptidyl prolyl-isomerase Pinl specifically binds phosphorylated serine or threonine residues immediately preceding proline (pSer/Thr-Pro) in a subset of proteins, and promotes the cis/trans isomerization of the peptide bond. Although Pin 1 has been shown to be involved in cell transformation and maintenance of malignant phenotype in prostate cancer cells (PCa), its specific substrates for malignant transformation remain largely determined. In this study, we utilized Pin 1 as a molecular probe to capture cancer-specific phosphorylated proteins. The glutathione-S-transferase (GST) pull-down and subsequent proteomic analyses newly identified 20 Pca-specific Pin 1 binding proteins(PINBP1-20). We further confirmed up-regulation of these genes in prostate cancer cell lines and tissues. Tissue micro-dissection based quantitative RT-PCR analysis of prostate cancer tissues revealed that the expression of PINBP1 tightly paralleled a higher probability and a shorter period of tumor recurrence following the operation. These results indicate that the Pinl -proteomics analysis can provide a useful tool to identify cancer-specific phosphorylated proteins, which could be potential prognostic marker or anti-cancer targets.