Endothelins Induce CCR7 Expression by Breast Tumor Cells via Endothelin Receptor A and Hypoxia-Inducible Factor-1
Endothelin expression is increased in breast tumors and is associated with invasion and metastasis, whereas CCR7 expression by breast tumor cells may have a role in the organ specificity of breast cancer spread. In this article, we have analyzed whether endothelins influence breast tumor cell expression of the chemokine receptor CCR7. Stimulation of human breast tumor cell lines with endothelins increased cell surface expression of CCR7 via endothelin receptor A. The iron chelators
... lators desferrioxamine and cobalt chloride, which induce hypoxia-inducible factor (HIF)-mediated transcription, also increased CCR7 expression; transfection of a dominantnegative version of the HIF regulatory subunit, HIF-1A, into MCF-7 cells abolished CCR7 induction by endothelins, indicating that increased expression is due to HIF-1 stabilization. Endothelin stimulation promoted invasion toward the CCR7 ligands CCL19 and CCL21. Endothelin-mediated chemokineindependent invasion itself is dependent on CCR7 activity and could be abolished using a CCR7-neutralizing monoclonal antibody. In human breast carcinomas, mRNA expression of endothelins correlated with the level of CCR7 expression, both of which were associated with the presence of lymph node metastases. Expression of the CCR7 ligands CCL19 and CCL21 was also higher in breast cancer patients with lymph node involvement compared with those without, but expression of these chemokines did not correlate with endothelin expression. These data show that CCR7 may be regulated by the breast tumor microenvironment and further support the use of endothelin receptor antagonists in the treatment of invasive and metastatic breast cancer. (Cancer Res 2006; 66(24): 11802-7) Materials and Methods Peptides and antagonists. Endothelin peptides, ET-RA antagonist 17) , and ET-RB antagonist BQ-788 (18) were obtained from American Peptide Co. (Sunnyvale, CA). Cell culture. Breast tumor cell lines MCF-7, SKBR3, and MDAMB231 were cultured in DMEM supplemented with 10% fetal bovine serum (FBS) and 25 Ag/mL insulin. Endothelins or endothelin receptor antagonists were added to the cell culture medium to give a final concentration of 100 ng/mL, and cells were incubated in the presence of peptides or antagonists for 24 hours unless otherwise stated.