CCL18 from tumor-associated macrophages promotes angiogenesis in breast cancer

// Ling Lin 1, 2, 3, * , Yong-Song Chen 3, * , Yan-Dan Yao 1, 2 , Jing-Qi Chen 1, 2 , Jia-Ning Chen 1, 2 , Song-Yin Huang 4 , Yun-Jie Zeng 5 , He-Rui Yao 6 , Si-Hai Zeng 7 , Yong-Shui Fu 7 , Er-Wei Song 1, 2 1 Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, P. R. China 2 Breast Tumor Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, P. R. China 3 Department of Internal Medicine, the First Affiliated Hospital, Shantou University Medical College, Shantou 515041, P. R. China 4 Department of Laboratory, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, P. R. China 5 Department of Pathology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, P. R. China 6 Department of Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, P. R. China 7 Guangzhou Blood Center, Guangzhou 510120, P. R. China * These authors have contributed equally to this work Correspondence to: Er-Wei Song, e-mail: songew@mail.sysu.edu.cn Yong-Shui Fu, e-mail: fuyongshui@sina.com Si-Hai Zeng, e-mail: isea2005@126.com Keywords: breast cancer, tumor-associated macrophage, angiogenesis, CCL18, PITPNM3 Received: April 27, 2015      Accepted: September 11, 2015      Published: September 23, 2015 ABSTRACT The infiltration of tumor-associated macrophages (TAMs) is associated with extensive angiogenesis, which contributes to a poor prognosis in breast cancer. However, anti-angiogenic therapy with VEGF-specific monotherapy has been unsuccessful in treating breast cancer, and the molecular mechanisms associated with chemoresistance remain unclear. Here, we investigated whether CCL18, a chemokine produced by TAMs, can stimulate angiogenesis in breast cancer, as well as the underlying mechanisms. Double immunohistochemical staining for CCL18 and CD34/CD31/vWF was performed in 80 breast cancer samples to study the correlation between CCL18 + TAMs and microvascular density (MVD). Cocultures of TAMs with human umbilical vein endothelial cells (HUVECs) were used to model the inflammatory microenvironment, and CCL18-induced angiogenesis was evaluated both in vitro and in vivo . We demonstrated that CCL18 + TAM infiltration positively associated with MVD in breast cancer samples, which was correlated with tumor metastasis and poor prognosis. We confirmed, both in vitro and in vivo , that CCL18 and VEGF synergistically promoted endothelial cell migration and angiogenesis. Conversely, blocking CCL18 or VEGF with neutralizing antibodies synergistically inhibited the promigratory effects of TAMs. Silencing PITPNM3, a putative CCL18 receptor, on the surface of HUVECs abrogated CCL18-mediated promigration and the enhancement of HUVEC tube formation, independently of VEGFR signaling. Moreover, CCL18 exposure induced the endothelial-mesenchymal transformation and activated ERK and Akt/GSK-3β/Snail signaling in HUVECs, thereby contributing to its pro-angiogenic effects. In conclusion, our findings suggest that CCL18 released from TAMs promotes angiogenesis and tumor progression in breast cancer; thus, CCL18 may serve as a novel target for anti-angiogenic therapies.