Anti-IRX1 monoclonal antibody, clone 2B22

Purpose: Single nucleotide polymorphisms (SNPs) are an important cause of functional variation in proteins leading to tumorigenesis. We aimed to identify candidate biomarkers with polymorphisms in gastric cancer (GC). Methods: The SNP microarray profile GSE29996 including 50 GC samples and 50 normal controls, and gene expression data GSE56807 consisting of 5 GC samples and 5 controls were downloaded from the Gene Expression Omnibus database. After preprocessing of raw data, GC-associated SNPs were identified using the Cochran-Armitage trend test, and differentially expressed genes (DEGs) were screened out using the limma package in R. Significant DEGs with risk associated SNP loci were screened using the Fisher combination test. Gene ontology function and pathway enrichment analyses were performed for DEGs with risk associated SNP loci by GenCLip online tool. Transcriptional regulatory analysis was also conducted for transcription factor and target DEGs. Results: A total of 79 DEGs with risk associated SNP loci were identified from GC samples compared with normal controls. These DEGs were mainly enriched in anatomical structure development, including embryo development. Additionally, DEGs were significantly involved in the NO1 pathway, including actin, alpha 1, skeletal muscle (ACTA1). In the regulatory network, transcription factor forkhead box L1 (FOXL1) regulated 26 DEGs with risk associated SNP loci, including Iroquois homeobox 1 (IRX1) rs11134044, sex determining region Y (SRY)-box1 (SOX1) rs9549447 and msh homeobox 1 (MSX1) rs41451149. Conclusions: IRX1, SOX1 and MSX1 with risk associated SNP loci may serve as candidate biomarkers for diagnosis and prognosis of GC.

The overexpression of IRX1 gene correlates with the growth arrest in gastric cancer. Furthermore, overexpression of IRX1 gene suppresses peritoneal spreading and long distance metastasis. To explore the precise mechanisms, we investigated whether restoring IRX1 expression affects the angiogenesis or vasculogenic mimicry (VM). Human umbilical vein endothelial cells (HUVECs) and chick embryo and SGC-7901 gastric cancer cells were used for angiogenesis and VM analysis. Small interfering RNA was used for analyzing the function of BDKRB2, a downstream target gene of IRX1. As results, the remarkable suppression on peritoneal spreading and pulmonary metastasis of SGC-7901 cells by IRX1 transfectant correlates to reduced angiogenesis as well as VM formation. Using the supernatant from SGC-7901/ IRX1 cells, we found a strong inhibiting effect on angiogenesis both in vitro and in chick embryo. SGC-7901/IRX1 cells revealed strong inhibiting effect on VM formation too. By gene-specific RNA interference for BDKRB2, or its effector PAK1, we got an effective inhibition on tube formation, cell proliferation, cell migration and invasion in vitro. In conclusion, enforcing IRX1 expression effectively suppresses peritoneal spreading and pulmonary metastasis via anti-angiogenesis and anti-VM mechanisms, in addition to previously found cell growth and invasion. BDKRB2 and its downstream effector might be potential targets for anti-cancer strategy. Oncogene (2011) 30, 4498-4508; doi:10.1038/onc.2011.154; published online 23 May 2011