Published in:
Open Access
01-01-2009 | Original Paper
Tiam1-deficiency impairs mammary tumor formation in MMTV-c-neu but not in MMTV-c-myc mice
Authors:
K. Strumane, T. Rygiel, M. van der Valk, J. G. Collard
Published in:
Journal of Cancer Research and Clinical Oncology
|
Issue 1/2009
Login to get access
Abstract
Background
Rho-like small GTPases, including RhoA, Rac1 and Cdc42, are crucial for the regulation of a large variety of biological processes such as the cytoskeletal organization and gene transcription. The activities of Rho GTPases are predominantly controlled by guanine nucleotide exchange factors (GEFs), which activate GTPases by catalyzing the exchange of bound GDP for GTP. Earlier, we have identified the Tiam1 gene as an invasion-inducing gene that encodes a specific activator (GEF) of the Rac GTPase. We found that Tiam1-mediated Rac signaling functions in various aspects of tumorigenicity including the formation and progression of Ras-induced skin tumors and Wnt-induced intestinal tumors. Here, we further distinguish the oncogenic pathways that depend on Tiam1 signaling in the mammary gland.
Material and methods
We crossed Tiam1 knockout mice with MMTV-c-myc and MMTV-c-neu transgenic mice, in which the expression of both oncogenes is targeted to the mammary gland leading to mammary tumorigenesis.
Results
We found Tiam1 important for Neu-induced tumor formation and progression but not for Myc-induced tumors. Tiam1-deficiency delayed Neu-induced tumor initiation and reduced metastasis but had no effect on the growth of the MMTV-c-neu tumors.
Conclusion
Our data indicate that the Rac activator Tiam1 contributes to tumorigenicity induced by specific oncogenic signaling pathways only.