Immunohistochemical expression analysis of leucine-rich PPR-motif-containing protein (LRPPRC), a candidate colorectal cancer biomarker identified by shotgun proteomics using iTRAQ.

BACKGROUND: Colorectal cancer (CRC) is the fourth most frequent cause of cancer deaths in the world. Novel biomarkers for the diagnosis, prognosis, and treatment of CRC are required to improve the clinical strategy.

METHODS: We applied shotgun proteomics using isobaric tags for relative and absolute quantitation (iTRAQ) to identify novel biomarkers of CRC, and then we detected leucine-rich PPR-motif-containing protein (LRPPRC) expression in 83 normal colorectal tissues and 133 CRC tissues by immunohistochemistry.

RESULTS: A total of 570 proteins were identified using iTRAQ. We validated the expression of LRPPRC protein by immunohistochemical analysis of the 77 proteins that showed expression changes in the cancer tissues >1.5-fold the levels in the normal tissues. The expression levels of LRPPRC were significantly higher in CRC tissues than those in normal colorectal tissues, and the expression levels were related with tumor differentiation and especially high in moderately differentiated CRC tissues.

CONCLUSION: We identified a novel, differentially expressed protein, LRPPRC, which has the potential to serve as a molecular target for diagnosis and/or prognosis of CRC.