Tumor angiogenesis is of paramount importance in solid tumor development. Elevated serum levels of YKL-40, a secreted heparin-binding glycoprotein have been associated with a worse prognosis from a variety of advanced human cancers. Yet the role of YKL-40 activity in these cancers is still missing. Here, we have shown that ectopic expression of YKL-40 in MDA-MB-231 breast cancer cells and HCT-116 colon cancer cells led to larger tumor formation with an extensive angiogenic phenotype than did control cancer cells in mice. Affinity purified recombinant YKL-40 protein promoted vascular endothelial cell angiogenesis in vitro, the effects similar to the activities observed using MDA-MB-231 and HCT-116 cell conditioned medium after transfection with YKL-40. Further, YKL-40 was found to induce the coordination of membrane-bound receptor syndecan-1 and integrin αvβ3 and activate an intracellular signaling cascade including focal adhesion kinase and MAP kinase Erk1/2 in endothelial cells. Also, blockade of YKL-40 using siRNA gene knockdown suppressed tumor angiogenesis in vitro and in vivo. Immunohistochemical analysis of human breast cancer revealed a correlation between YKL-40 expression and blood vessel density. These findings provide novel insights into angiogenic activities and molecular mechanisms of YKL-40 in cancer development.

GATA3, a transcription factor that regulates T lymphocyte differentiation and maturation, is exclusively expressed in early stage well differentiated breast cancers but not in advanced invasive cancers. However, little is understood regarding its activity and the mechanisms underlying this differential expression in cancers. Here, we employed GATA3-positive, non-invasive (MCF-7) and GATA3-negative, invasive (MDA-MB-231) breast cancer cells to define its role in the transformation between these two distinct phenotypes. Ectopic expression of GATA3 in MDA-MB-231 cells led to a cuboidal-like epithelial phenotype and reduced cell invasive activity. These cells also increased E-cadherin expression but decreased levels of vimentin, N-cadherin, and MMP-9. Further, MDA-MB-231 cells expressing GATA3 grew smaller primary tumors without metastasis compared with larger metastatic tumors derived from control MDA-MB-231 cells in xenografted mice. GATA3 was found to induce E-cadherin expression through binding GATA-like motifs located in the E-cadherin promoter. Blockade of GATA3 using small interfering RNA gene knockdown in MCF-7 cells triggered fibroblastic transformation and cell invasion, resulting in distant metastasis. Studies of human breast cancer showed that GATA3 expression correlated with elevated E-cadherin levels, ER expression, and long disease-free survival. These data suggest that GATA3 drives invasive breast cancer cells to undergo the reversal of epithelial-mesenchymal transition, leading to the suppression of cancer metastasis.GATA3 (GATA-binding protein 3) is a family member of zinc finger transcription factors (GATA1-GATA6) that bind with high affinity to the consensus DNA sites (T/A-GATA-A/G) (1, 2). GATA1, GATA2, and GATA3 are primarily expressed by hematopoietic cells, whereas GATA4, GATA5, and GATA6 are detectable in the cardiovascular system and endodermus-derived tissues, such as lung, liver, intestine, and pancreas (3). Functional studies of GATA3 in the lineage specification of hematopoietic cells have revealed that GATA3 mediates thymocyte maturation and is abundantly expressed by mature T lymphocytes (4, 5). Recently, it also has been found that GATA3 plays an essential role in the morphogenesis of embryonic mammary tissue. In the adult mammary gland, GATA3 acts on ductal epithelium to maintain the differentiation of luminal epithelial cells (6 -8); thereof, GATA3 is recognized as a key regulator of mammary tissue development and mammary gland formation.Over the past decade, considerable attention has been focused on the differential expression profile of GATA3 in different subtypes of human breast cancers. For instance, studies with differential gene expression techniques, including serial analysis of gene expression (available on the NCI, National Institutes of Health, Web site) and gene microarray have shown that GATA3 is highly expressed in estrogen receptor (ER) 2 -positive, early stage well differentiated breast cancers other than ER-negative, invasive cancers that are associated with worse ...

BACKGROUND: An effective cancer therapeutic must selectively target tumours with minimal systemic toxicity. Expression of a cytotoxic protein using Salmonella typhimurium would enable spatial and temporal control of delivery because these bacteria preferentially target tumours over normal tissue. METHODS: We engineered non-pathogenic S. typhimurium to secrete murine TNF-related apoptosis-inducing ligand (TRAIL) under the control of the prokaryotic radiation-inducible RecA promoter. The response of the RecA promoter to radiation was measured using fluorometry and immunoblotting. TRAIL toxicity was determined using flow cytometry and by measuring caspase-3 activation. A syngeneic murine tumour model was used to determine bacterial accumulation and the response to expressed TRAIL. RESULTS: After irradiation, engineered S. typhimurium secreted TRAIL, which caused caspase-3-mediated apoptosis and death in 4T1 mammary carcinoma cells in culture. Systemic injection of Salmonella and induction of TRAIL expression using 2 Gy g-irradiation caused a significant delay in mammary tumour growth and reduced the risk of death by 76% when compared with irradiated controls. Repeated dosing with TRAIL-bearing Salmonella in conjunction with radiation improved the 30-day survival from 0 to 100%. CONCLUSION: These results show the pre-clinical utility of S. typhimurium as a TRAIL expression vector that effectively reduces tumour growth and extends host survival.