Identification Of Specific Biomarkers For Gastric Adenocarcinoma By ITRAQ Proteomic Approach

Objectives:The aim of this study was to identify biomarkers for gastric cancer(GC)by iTRAQ.Methods : This present study utilized the iTRAQ approach to profile the differentially expressed proteins in Her-2 negative stage III – IV human gastric adenocarcinoma.We performed Gene Ontology(GO)and pathway analysis in order to explore the role of dysregulated proteins in tumor progression.Selected differentially expressed proteins were validated by Western Blot and immunofluorecence staining.We also performed migration and invasion experiments using a human gastric cancer line in order to exam the role of these proteins in tumor metastasis.Results : 1 ? Using proteins extracted from a panel of 4 pairs of gastric adenocarcinoma samples(stage III-IV,Her-2 negative)and their adjacent normal tissues,we identified 10 up regulated and 9 down regulated proteins in all four pairs of GC samples compared to adjacent normal gastric tissue.The up regulated proteins are mainly involved in cell motility,while the down regulated proteins are mitochondrial enzymes involved in energy metabolism.2?The expression of three up regulated proteins(AnnexinA1,NNMT,fibulin-5)and one of the down regulated proteins(UQCRC1)was validated by Western Blot in 97 GC samples.AnnexinA1 was up regulated in 61.36% of stage I/II GC samples compared to matched adjacent normal gastric tissue,and its expression increased further in stage III/IV samples.3?Knockdown of AnnexinA1 by siRNA significantly inhibited GC cell migration and invasion,whereas over expression of AnnexinA1 promoted migration and invasion.We found decreased expression of UQCRC1 in all stages of GC samples.Our data suggest that increased cell motility and decreased mitochondrial energy metabolism are important hallmarks during the development of GC.Conclusions:Our study revealed the role of AnnexinA1,NNMT,Fibulin-5 and UQCRC1 in gastric cancer progression.We also revealed the role of decreased expression of UQCRC1,a mitochondrial enzyme involved in energy metabolism,in GC development.Future studies will clarify how these proteins participate in gastric cancer development and progression.