Systems biology approach to identification of biomarkers for metastatic progression in gastric cancer

Gastric cancer is usually diagnosed at later stages (stages III and IV) in China, and the overall 5-year survival rate is low at 40%. Metastases are responsible for the majority of cancer fatalities. The molecular mechanisms governing metastasis are poorly understood. We have analyzed gene expression data based on gene interaction networks and molecular pathways rather than separate genes utilizing hierarchical cluster analysis, Gene ontology analysis and pathway analysis. We have analyzed gene expression data from advanced gastric cancer tissues, corresponding adjacent noncancerous gastric tissues and its peritonium metastasis. Our studies indicated that metastatic tumor was related to changes in apoptosis pathway and proteasome degradation pathway, TRAF2 and IRF3 are up-regulated in apoptosis pathway, NEDD4 and UBE1 are up-regulated in proteasome degradation pathway. The advent of high-throughput investigation of gene using Microarray technology, a systems approach relying on groups of interacting genes is essential for understanding the processes of cancer. We have identified apoptosis pathway and proteasome degradation pathway associated with metastasis.