Objective: To explore the biological function of TIAM1 gene in colorectal cancer cells and its role in cell signaling network by doing bioinformatics analysis. Methods: Firstly

we forecasted the miRNA which interacted with TIAM1 by using miRNA predicting tools

next analyzed the miRNA which related with the deletion of TIAM1 by using the expression profiles of colorectal cancer cell lines SW480 with deleted TIAM1; then selected the miRNA (hsa-mir-340) which related with TIAM1 from the above two analyses. We forecasted target genes of the miRNA and doing pathway enrichment analysis. We compared the enrichment results and TIAM1 interaction protein pathway enrichment result.We did the pathway enrichment for the gene set whose expression profile logarithmic ratio was greater than 1 compared with that of wild type sw480 cell lines.We did the pathway enrichment using the protein which in protein-protein interaction network of TIAM1.We then did the pathway enrichment for the protein which interacted with TIAM1 directly and indirectly to epithelial mesenchymal transition (EMT) markers named E-cadhrin and Vimentin. Results: All of the direct prediction and indirect prediction show that microRNA hsa-mir-340 can interact with TIAM1 and coordinate with TIAM1 on the function seen from the pathway enrichment result.We analyzed the expression data of the SW480 which deleted the TIAM1 and clarified that the lack of the TIAM1 is related to the over-active of the P53 signal pathway

DNA damage response

Toll-like receptor signal pathway and so on.That means the lack of the TIAM1 may related to the enhance the antitumor effect.According to the pathway analysis results

TIAM1 gene participated in a lot of signaling pathways such as the cell adhesion

cytoskeleton remodeling

cell proliferation and growth

etc. These signaling pathways were possibly related with the phenomenon of the EMT in colorectal cancer. Conclusions: hsa-mir-340 can regulate the expressions of TIAM1.Signal pathway related with TIAM1 has close relationship with cancer metastasis.TIAM1 can influence the function of EMT markers E-cadherin and Vimentin and promote the colorectal cancer occurrence and metastasis by affecting EMT signal pathways such as TGF-β receptor、androgen receptor、NF-kB、MAPK.