@article{74a3eb05f4fe4b16afbbe04a45ded2e0,
title = "E-cigarette promotes breast carcinoma progression and lung metastasis: Macrophage-tumor cells crosstalk and the role of CCL5 and VCAM-1",
abstract = "Young women represent a target of E-cigarette (E-cig) companies, raising concern for potential connections with breast cancer (BC) that have not yet been elucidated. We hypothesized that E-cig promotes BC development and lung metastasis possibly through BC-monocyte/tumor-associated macrophage (TAM) crosstalk via CCL5 and V-CAM-1 axes. We demonstrated that E-cig promoted the infiltration of circulating monocytes in mammary fat pad (MFP) model. Furthermore, E-cig exposure significantly enhanced BC cell growth in MFP tumor and metastatic lung colonization; immunohistochemical stains illustrated the increase of TAMs infiltration, reduced BC cell apoptosis and increased proliferation index after E-cig exposure. In vitro studies show E-cig vapor condensate (EVC) treatment upregulated protein expressions of CCL5, V-CAM-1, and other pro-tumorigenic factors in BC cells. Mechanistically, co-culture system demonstrated both EVC and macrophages independently stimulated BC cell growth and the migration via CCL5/CCR1/CCR5 axis. During metastasis, E-Cig exposure stimulated BC cell survival via direct interaction with infiltrated macrophages, regulated by VCAM-1 and integrin α4β1. Our findings, for the first time, showed that E-cig promotes BC growth and metastasis. This study highlights the critical role of TAMs via CCL5 and VCAM-1 pathways in E-cig promoted BC tumor development.",
keywords = "Breast cancer, CCL5, E-Cigarette, Lung metastasis, Macrophages, V-CAM-1",
author = "Kien Pham and Do Huynh and Le Le and Daniel Delitto and Lei Yang and Jing Huang and Yibin Kang and Steinberg, {Michael B.} and Jieliang Li and Lanjing Zhang and Dongfang Liu and Tang, {Moon Shong} and Chen Liu and He Wang",
note = "Funding Information: Our in vivo studies clearly demonstrated the enhancement of tumor-infiltrated macrophages at pulmonary metastatic sites. To understand the impact of macrophage filtration on metastatic development, we studied the interaction of tumor cells and monocytes in an in vitro cell-cell binding assay [43,44]. This analysis demonstrated that E-Cig exposure supported direct binding of monocytes with BC cells. Mechanistically, EVC treatment upregulated VCAM-1 mRNA expression >5 folds in EpRAS BC cells; while there is no change in mRNA level of IGA4 and IGB1 genes encoding integrin subunits α4 and β1 (Fig. 5B); monocyte/EpRAS binding can be effectively inhibited by BIO 5192 (Fig. 5A, top and bottom), a highly potent and selective inhibitor of integrin α4β1 (VLA-4). This phenomenon was also confirmed in 4T07 cells (Fig. 6E). Altogether, the data established in two different models of murine breast cancer suggested that this receptor and its ligand VCAM-1 play a significant role in mediating myeloid-tumor crosstalk in metastasis.According to a recent survey on vaping usage, an estimated 2.1 million middle school and high school students reported using E-Cigarettes in 2017 and this number jumped to 4.9 million in 2018 [55]. The increasing popularity of vaping, especially in teenagers, raises an alarm in the public health community. Early evidence has revealed the direct impact of E-Cig on overall health, the development of the adolescent brain, and the potential for addiction [56]. Its contribution to cancer, however, has rarely been reported or discussed. In this study using both animal models and cell-based systems, we uncover versatile roles of E-Cig exposure in BC progression and lung metastasis. As summarized in Fig. 8, our data revealed that E-Cig exposure promoted the infiltration of circulating monocytes into the tumor microenvironment through the expression of chemokine receptors CCR1/CCR5 and the secretion of their ligand CCL5 by monocytes and cancer cells, respectively. In the primary tumor, both E-Cig exposure and infiltrating macrophages can induce growth and migration of BC cells through the regulation of CCL5/CCR1/CCR5 axis and possibly other factors related to tumor proliferation and metastasis. During the stage of metastasis, E-Cig exposure supports the survival of disseminated BC cells and colonization via interaction with infiltrated macrophages, regulated in part by VCAM-1 and integrin α4β1. Our findings provide insight into the potential mechanism by which E-Cig exposure modulates progression and pulmonary metastasis of BC. Further, these findings contribute timely scientific evidence to stress public awareness regarding E-Cig regulation, particularly in the younger population.Our study also shows that direct E-Cig treatment upregulates VCAM-1 mRNA expression >5 folds in EpRAS BC cells. Further, monocyte/EpRAS binding can be effectively inhibited by BIO 5192, a highly potent and selective inhibitor of integrin α4β1 (VLA-4), suggesting that this receptor and its ligand, VCAM-1, play a significant role in mediating crosstalk between BC cells and TAMs. VCAM-1, an immunoglobulin (Ig)-like adhesion molecule with seven extracellular Ig domains, is aberrantly expressed in BC cells and binds to its receptor, α4β1 integrin [67,68]. Most early studies on the crosstalk between BC cells and TAMs focus on soluble factors [69]. However, recent studies have shown that depleting lung macrophages or preventing the recruitment of macrophages into the lung significantly decreases lung metastasis via unknown molecular mechanisms [69,70]. Our data regarding VCAM-1 induction provide one such mechanism [45]. Tumor cells entering the lung parenchyma are typically surrounded by macrophages, possibly related to an underlying innate immune response. The close proximity of macrophage and tumor cells subsequently facilitates contact between the α4 integrins and VCAM-1, recruits Ezrin, a cytoplasmic adaptor protein that links the actin cytoskeleton to the VCAM-1 cytoplasmic tail, leading to phosphorylation of Ezrin [65]. Once activated, Ezrin serves as an adaptor that binds both PI3K and its downstream mediator, AKT, leading to activation of AKT-mediated pro-survival signaling [45]. Therefore, α4 integrin-expressing TAMs create a favorable microenvironment for high VCAM-1 expressing BC cells in the lungs as well as primary tumors. We provide support of this proposed interaction, demonstrating that BC-TAM binding is associated with reduced apoptosis of BC cells in vitro; this apoptotic resistance is negated after BC-TAM binding is hindered by an α4 integrin inhibitor. Publisher Copyright: {\textcopyright} 2020",
year = "2020",
month = oct,
day = "28",
doi = "10.1016/j.canlet.2020.08.010",
language = "English (US)",
volume = "491",
pages = "132--145",
journal = "Cancer Letters",
issn = "0304-3835",
publisher = "Elsevier Ireland Ltd",
}