Cyclooxygenase-2 Up-regulates CCR7 via EP2/EP4 Receptor Signaling Pathways to Enhance Lymphatic Invasion of Breast Cancer Cells*
- ‡Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, the §Department of Surgery, Kaohsiung Medical University, Kaohsiung 807, ∥Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, ¶National Sun Yat-Sen University-Kaohsiung Medical University Joint Research Center, Kaohsiung 804, and **Center for Gene Regulation and Signal Transduction Research, National Cheng Kung University, Tainan 701, Taiwan
- 1 To whom correspondence should be addressed: 70, Lien-Hai Rd., Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, Republic of China. Fax: 886-7-5250197; E-mail: hung1228{at}ms10.hinet.net.
Abstract
Recent studies demonstrate that cyclooxygenase-2 (COX-2) expression is frequently associated with lymph node metastasis. However, the mechanism by which COX-2 increases the invasion of cancer cells to lymph node is unclear. CCR7 is a chemokine receptor that plays important roles in the mediation of migration of leukocytes and dendritic cells toward lymphatic endothelial cells (LECs) that express receptor ligand CCL21. We found that treatment of prostaglandin E2 or ectopic expression of COX-2 in MCF-7 cells up-regulated CCR7 expression. On the contrary, knockdown of COX-2 by small hairpin RNA reduced CCR7 in COX-2-overexpressing MDA-MB-231 cells. Interaction of CCR7 and CCL21 was important for the migration of breast cancer cells toward LECs because antibodies against these two molecules inhibited the migration. We also found that COX-2 increased CCR7 expression via the EP2 and EP4 receptor in breast cancer cells. EP2 and EP4 agonists stimulated CCR7 in MCF-7 cells, whereas antagonists or small hairpin RNA of EP2 and EP4 attenuated CCR7 in MDA-MB-231 cells. Protein kinase A and AKT kinase were involved in COX-2-induced CCR7. Pathological analysis demonstrated that COX-2 overexpression was associated with CCR7, EP2, and EP4 expressions in breast tumor tissues. In addition, CCR7 expression in COX-2-overexpressing tumors was significantly correlated with lymph node metastasis. Collectively, we suggest that CCR7 is a down-stream target for COX-2 to enhance the migration of breast cancer cells toward LECs and to promote lymphatic invasion.
Footnotes
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↵2 The abbreviations used are: COX, cyclooxygenase; LECs, lymphatic endothelial cells; PG, prostaglandin; shRNA, small hairpin RNA; PKA, protein kinase A; VEGF-C, vascular growth factor C; VEGFR3, vascular growth factor receptor 3; RT, reverse transcription; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; ERK, extracellular signal-regulated kinase.
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↵* This work was supported by the grants from the Center for Gene Regulation and Signal Transduction Research, National Cheng Kung University, and National Sun Yat-Sen University-Kaohsiung Medical University Joint Research Center. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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The on-line version of this article (available at http://www.jbc.org) contains supplemental Figs. 1–4.
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- Received December 10, 2007.
- Revision received February 29, 2008.
- The American Society for Biochemistry and Molecular Biology, Inc.
