Lentivirus-mediated silencing of Tiam1 gene influences multiple functions of a human colorectal cancer cell line.

T lymphoma invasion and metastasis 1 (Tiam1) is a metastasis-related gene of T lymphoma that is also involved in the metastasis of a variety of other cancers. In this study, we tested the hypothesis that Tiam1 is a determinant of proliferation and metastasis in colorectal cancer, and we examined the effect of the inhibition of Tiam1 expression on proliferation and metastasis. We succeeded in establishing the Tiam1 knockdown colorectal cancer cell line using human immunodeficiency virus lentivirus-mediated RNA interference (RNAi) and found that the silencing of Tiam1 resulted in the effective inhibition of in vitro cell growth and of the invasive ability of colorectal cancer cells. Using an orthotopic xenograft model in nude mice, we confirmed that Tiam1 silencing could reduce tumor growth by subcutaneous injection and could suppress lung and liver metastases of colorectal cancer cells. Our results suggest that Tiam1 truly plays a causal role in the metastasis of colorectal cancer and that RNAi-mediated silencing of Tiam1 may provide an opportunity to develop a new treatment strategy for colorectal cancer.