The aim of the present study was to screen gastric cancer (GC) tissue and 
adjacent tissue for differences in mRNA and circular (circRNA) expression, to 
analyze the differences in circRNA and mRNA expression, and to investigate the 
circRNA expression in gastric carcinoma and its mechanism. circRNA and mRNA 
differential expression profiles generated using Agilent microarray technology 
were analyzed in the GC tissues and adjacent tissues. qRT-PCR was used to verify 
the differential expression of circRNAs and mRNAs according to the interactions 
between circRNAs and miRNAs as well as the possible existence of miRNA and mRNA 
interactions. We found that: i) the circRNA expression profile revealed 1,285 
significant differences in circRNA expression, with circRNA expression 
downregulated in 594 samples and upregulated in 691 samples via interactions 
with miRNAs. The qRT-PCR validation experiments showed that hsa_circRNA_400071, 
hsa_circRNA_000543 and hsa_circRNA_001959 expression was consistent with the 
microarray analysis results. ii) 29,112 genes were found in the GC tissues and 
adjacent tissues, including 5,460 differentially expressed genes. Among them, 
2,390 differentially expressed genes were upregulated and 3,070 genes were 
downregulated. Gene Ontology (GO) analysis of the differentially expressed genes 
revealed these genes involved in biological process classification, cellular 
component classification and molecular function classification. Pathway analysis 
of the differentially expressed genes identified 83 significantly enriched 
genes, including 28 upregulated genes and 55 downregulated genes. iii) 69 
differentially expressed circRNAs were found that might adsorb specific miRNAs 
to regulate the expression of their target gene mRNAs. The conclusions are: i) 
differentially expressed circRNAs had corresponding miRNA binding sites. These 
circRNAs regulated the expression of target genes through interactions with 
miRNAs and might become new molecular biomarkers for GC in the future. ii) 
Differentially expressed genes may be involved in the occurrence of GC via a 
variety of mechanisms. iii) CD44, CXXC5, MYH9, MALAT1 and other genes may have 
important implications for the occurrence and development of GC through the 
regulation, interaction, and mutual influence of circRNA-miRNA-mRNA via 
different mechanisms.