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[摘要]：The endothelin (ET) axis, often deregulated in cancers, is a promising target for anticancer strategies. Whereas previous investigations have focused mostly on ET action in malignant cells, we chose a model allowing separate assessment of the effects of ETs and their receptors ETAR and ETBR in the tumor cells and the stromal compartment, which is increasingly recognized as a key player in cancer progression. In homozygous spotting lethal rats (sl/sl), a model of constitutive ETBR deficiency, we showed significant reduction of growth and metastasis of MAT B III rat mammary adenocarcinoma cells overexpressing ETAR and ET-1 but negative for ETBR. Lack of stromal ETBR expression did not influence angiogenesis. However, it was correlated with diminished infiltration by tumor-associated macrophages and with reduced production of tumor necrosis factor-alpha, both known as powerful promoters of tumor progression. These effects were almost completely abolished in transgenic sl/sl rats, wherein ETBR function is restored by expression of an intact ETBR transgene. This shows that tumor growth and metastasis are critically dependent on ETBR function in cells of the microenvironment and suggests that successful ETR antagonist therapy should also target the stromal component of ET signaling. [Mol Cancer Ther 2009;8(8):2452-60] |
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