Abstract
Gastric cancer (GC) is a heterogeneous disease that is not well detected by current tumor markers. Identifying molecular markers that can predict the potential for tumor progression is important for appropriate individualized therapy. Using the Cancer Metastasis Research Center microarray database (17K cDNA microarray), we identified genes that were differentially expressed between 96 cancer and 98 normal gastric tissues using significant analysis of microarrays. From these, we selected genes that were overexpressed more than twofold in tumor tissues that encode secreted proteins. The selected genes were validated with ELISA using the sera of 96 GC patients and 48 healthy donors. Our first round of selection included 6510 genes that were differentially expressed between 96 cancer and 98 normal gastric tissues with a minimal false discovery rate of 0.005%. Out of those genes, we picked 386 that encoded secreted proteins based on the SOURCE database. Of these genes, we focused on 55 that were overexpressed more than twofold in GC compared to normal tissues. With Ingenuity Pathway Analysis, we found 34 genes related to cancer. One in particular, chemokine growth-regulated oncogene 1, CXCL1, has been linked to cancer progression in various cancer types, but not yet to GC. Levels of CXCL1 in serum samples of GC patients were significantly higher compared with healthy donors (P < 0.05). Within GC patients, CXCL1 serum levels increased according to tumor stage and lymph node metastasis. The CXCL1 gene appears to be a candidate marker for GC progression.