Mouse anti-Chicken p95PKL/GIT monoclonal antibody, clone 24

When properly employed, targeted therapies are effective cancer treatments. However, the development of such therapies requires the identification of targetable drivers of cancer development and metastasis. The expression and nuclear localization of the transcriptional coactivators Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) are increased in many human cancers, and experimental evidence indicates that aberrant YAP or TAZ activation drives tumor formation and metastasis. Although these findings make YAP and TAZ appealing therapeutic targets, both have important functions in adult tissues, so directly targeting them could cause adverse effects. The identification of pathways active in cancer cells and required for YAP/TAZ activity could provide a way to inhibit YAP and TAZ. Here, we show that SRC proto-oncogene, nonreceptor tyrosine kinase (SRC) is an important driver of YAP/TAZ activity in human breast cancer and melanoma cells. SRC activation increased YAP/TAZ activity and the expression of YAP/TAZ-regulated genes. In contrast, SRC inhibition or knockdown repressed both YAP/TAZ activity and the expression of YAP/TAZ-regulated genes. We also show that SRC increases the activity of YAP and TAZ by repressing large tumor suppressor homolog (LATS), and we identify the GTPase-activating protein GIT ArfGAP 1 (GIT1) as an SRC effector that regulates both YAP and TAZ. Importantly, we demonstrate that SRC-mediated YAP/TAZ activity promotes tumor growth and enhances metastasis and that SRC-dependent tumor progression depends, at least in part, on YAP and TAZ. Our findings suggest that therapies targeting SRC could help manage some YAP/TAZ-dependent cancers.

The growth of new blood vessels by angiogenesis and their stabilization by the recruitment of perivascular mural cells are thought to be two sequential, yet independent events. Here we identify molecular links between both processes through the beta Pix and integrin alpha(v)beta(8) proteins. Bubblehead (bbh) mutants with a genetic mutation in beta Pix show defective vascular stabilization. beta Pix is a guanine nucleotide exchange factor and scaffold protein that binds many proteins including Git1, which bridges beta Pix to integrins at focal adhesions. Here we show that the ability of beta Pix to stabilize vessels requires Git1 binding residues. Knockdown of Git1 leads to a hemorrhage phenotype similar to loss of integrin alpha(v), integrin beta(8) or beta Pix, suggesting that vascular stabilization through beta Pix involves interactions with integrins. Furthermore, double loss of function of beta Pix and integrin alpha(v) shows enhanced hemorrhage rates. Not only is vascular stability impaired in these embryos, but we also uncover a novel role of both beta Pix and integrin alpha(v)beta(8) in cerebral angiogenesis. Downregulation of either beta Pix or integrin alpha(v)beta(8) results in fewer and morphologically abnormal cerebral arteries penetrating the hindbrain. We show that this is coupled with a significant reduction in endothelial cell proliferation in bbh mutants or integrin alpha(v)beta(8) morphants. These data suggest that a complex involving beta Pix, GIT1 and integrin alpha(v)beta(8) may regulate vascular stability, cerebral angiogenesis and endothelial cell proliferation in the developing embryo. (C) 2011 Elsevier Inc. All rights reserved.