The lymphatic system is an important route for cancer dissemination, and lymph node metastasis (LNM) serves as a critical prognostic determinant in cancer patients. We investigated the contribution of COX-2–derived prostaglandin E2 (PGE2) in the formation of a premetastatic niche and LNM. A murine model of Lewis lung carcinoma (LLC) cell metastasis revealed that COX-2 is expressed in DCs from the early stage in the lymph node subcapsular regions, and COX-2 inhibition markedly suppressed mediastinal LNM. Stromal cell–derived factor-1 (SDF-1) was elevated in DCs before LLC cell infiltration to the lymph nodes, and a COX-2 inhibitor, an SDF-1 antagonist, and a CXCR4 neutralizing antibody all reduced LNM. Moreover, LNM was reduced in mice lacking the PGE2 receptor EP3, and stimulation of cultured DCs with an EP3 agonist increased SDF-1 production. Compared with WT CD11c+ DCs, injection of EP3-deficient CD11c+ DCs dramatically reduced accumulation of SDF-1+CD11c+ DCs in regional LNs and LNM in LLC-injected mice. Accumulation of Tregs and lymph node lymphangiogenesis, which may influence the fate of metastasized tumor cells, was also COX-2/EP3–dependent. These results indicate that DCs induce a premetastatic niche during LNM via COX-2/EP3–dependent induction of SDF-1 and suggest that inhibition of this signaling axis may be an effective strategy to suppress premetastatic niche formation and LNM.
Fumihiro Ogawa, Hideki Amano, Koji Eshima, Yoshiya Ito, Yoshio Matsui, Kanako Hosono, Hidero Kitasato, Akira Iyoda, Kazuya Iwabuchi, Yuji Kumagai, Yukitoshi Satoh, Shuh Narumiya, Masataka Majima