OBJECTIVETo study genome-wide gene expression changes in gastric cancer cells after iodine-125 ¹²⁵(I) particle irradiation.

METHODS¹²⁵I particles were used to irradiate three gastric cancer cell lines of various differentiation levels:high (BGC-823) , medium (AGS) and low (NCI-N87) .Whole-genome gene expression was investigated with microarray. The gene expression in iodine-125 irradiated and untreated cancer cells was compared, and the genes with transcript levels altered for at least 2 folds (P < 0.05) were selected. The change in gene expression levels was verified by using quantitative real-time (qRT) -PCR.

RESULTSThe three gastric cancer cell lines received the same dose rate of ¹²⁵I particle irradiation. Cluster analysis showed that the Gene Ontology (GO) categories did not change in the three cell lines, but changes in gene expression levels were evident for many genes. After ¹²⁵I particle irradiate NCI-N87 cells, 895 genes were up-regulated, 786 genes were down-regulated; AGS was irradiated by ¹²⁵I seed, there were 124 genes upregulated, 161 genes were down-regulated; BGC-823 cells were treated by ¹²⁵I seed irradiation, 2 412 genes upregulated, 3 243 downregulated genes. After ionizing radiation can cause very complex transcriptional regulation changes, KEGG pathway analysis shows that these differentially expressed genes overlap in a particular cell pathway. Four genes, TRAF3IP2-AS1, SDC1, RABL2B and NOM, were found having at least 2-fold difference in expression (P < 0.05) , and the gene expression alteration was confirmed by qRT-PCR.

CONCLUSIONS¹²⁵I particle irradiation caused gene expression changes in gastric cancer cells. The expressions of TRAF3IP2-AS1, SDC1, RABL2B and NOM are altered significantly in all three cell lines studied, indicating that these genes may play an important role in the ¹²⁵I seed treatment of gastric cancer. These genes could be potential targets for developing anti-cancer drugs in the future.