Antisense Tiam1 down-regulates the invasiveness of 95D cells in vitro.

As a specific guanine nucleotide exchange factor of Rac1, Tiam1 (T-lymphoma invasion and metastasis inducing protein 1) is involved in a number of cellular events, such as cytoskeleton reorganization, cell adhesion, and cell migration. Since Tiam1 was implicated in the invasion and metastasis of T-lymphoma cells and breast tumor cells, we compared the expression level of Tiam1 in two human giant-cell lung carcinoma cell strains with high or low metastasis potential, and found that Tiam1 expression level in high-metastatic 95D cells was higher than that in low-metastatic 95C cells. To further confirm the role of Tiam1 in invasion and metastasis, we constructed the antisense Tiam1 expression plasmid (pcDNA3-anti-Tiam1), which was transfected into 95D cells.