CCL18 from tumor-associated macrophages promotes angiogenesis in breast cancer.

Song-Yin Huang,He-Rui Yao,Yan-Dan Yao,Jing-Qi Chen,Jia-Ning Chen,Si-Hai Zeng,Yun-Jie Zeng,Ling Lin,Yong-Shui Fu,Yong-Song Chen,Er-Wei Song

doi:10.18632/oncotarget.5325

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.

Highlights

Angiogenesis, the formation of new blood vessels, facilitates tumor growth, progression, and aggressiveness [1]
We demonstrated that CCL18+ tumor-associated macrophages (TAMs) infiltration positively associated with microvascular density (MVD) in breast cancer samples, which was correlated with tumor metastasis and poor prognosis
Consistent with our previous findings [15], the number of CCL18+ TAMs increased with higher tumor burden as defined by tumor size (p < 0.001) and staging (p = 0.014), as well as with aggressive tumor biology defined by advanced histological grading (p = 0.035), lymph node metastasis (p < 0.001), and distant metastasis (p = 0.018)

Summary

Introduction

Angiogenesis, the formation of new blood vessels, facilitates tumor growth, progression, and aggressiveness [1]. Numerous studies have reported a correlation between increased angiogenesis and poor prognosis in various cancers, such as breast, prostate, gastrointestinal, cervical, uterine, and lung cancer; inhibiting angiogenesis is potentially a promising strategy for numerous cancer therapies [2, 3]. Various cytokines contribute to tumor angiogenesis, including vascular endothelial growth factor (VEGF), basic fibroblast growth factor, epidermal growth factor, interleukin (IL)-8, and tumor necrosis factor-α [4,5]. VEGF is the primary cytokine that promotes angiogenesis in solid tumors by promoting endothelial cell proliferation, migration, and vascular permeability. The combination of anti-angiogenic therapy with conventional therapies, in particular radiation therapy and cytotoxic chemotherapy, has led to significant increases in overall survival in certain cancers such as colorectal carcinoma, metastatic renal cell carcinoma, non-squamous non-small cell lung cancer, and recurrent glioblastoma [4,5,6]

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Results

Conclusion