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

肽基-Pro-异构酶Pin1与蛋白质中紧靠在Pro之前的磷酸化丝氨酸或苏氨酸残基(pSer/Thr-Pro)特异性结合，促进肽键的顺式/反式异构化。尽管Pin 1已被证明与前列腺癌(Pca)的细胞转化和恶性表型的维持有关，但其恶性转化的特异性底物仍在很大程度上仍未确定。在这项研究中，我们使用Pin 1作为分子探针来捕获癌症特异的磷酸化蛋白。谷胱甘肽-S-转移酶(GST)下拉和随后的蛋白质组学分析新发现了20个Pca特异的Pin1结合蛋白(PINBP1-20)。我们进一步证实了这些基因在前列腺癌细胞系和组织中的上调。前列腺癌组织的组织显微切割定量RT-PCR分析显示，PINBP1的表达与术后肿瘤复发的概率和时间短密切相关。这些结果表明，Pinl蛋白质组学分析可以提供一种有用的工具来识别癌症特异的磷酸化蛋白，这些蛋白可能是潜在的预后标志或抗癌靶点。

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.