Proteome Analyses Reveal S100A11, S100P, and RBM25 Are Tumor Biomarkers in Colorectal Cancer

Abstract

The prognosis for colorectal cancer (CRC) patients is drastically impacted by the presence of lymph node or liver metastases at diagnosis or resection. On this basis it is sought to identify novel proteins as biomarkers and determinants of CRC metastasis. Proteomic analyses are undertaken using primary tissues from ten Chinese CRC patients presenting with or without liver metastases and immunohistochemistry used to validate selected proteins in an independent patient cohort. Comparing CRC against paired normal adjacent tissues identifies 1559 differentially expressed proteins (DEPs) with 974 upregulated and 585 downregulated proteins, respectively. The highest number of DEPs is selectively associated with metastatic tumors (519 upregulated and 267 downregulated proteins, respectively) with a smaller number of unique DEPs identified only in non-metastatic CRC cases (116 upregulated and 29 downregulated proteins, respectively). The remaining DEPs are commonly expressed in both non-metastatic and metastatic tumors. The upregulation of three representative DEPs (S100A11, S100P, and RBM25) is confirmed using immunohistochemistry against 154 CRC tissues embedded in a tissue microarray. The data reveal both previously identified CRC biomarkers along with novel candidates which provide a ready resource of DEPs in CRC for further investigation.