E-cigarette promotes breast carcinoma progression and lung metastasis: Macrophage-tumor cells crosstalk and the role of CCL5 and VCaM-1.

Introduction:
This text provides an in-depth analysis of a study investigating the relationship between electronic cigarette (e-cigarette) use and breast cancer progression and metastasis. The study uses both in vitro and in vivo models to examine the effects of e-cigarette exposure on breast cancer cells and tumor-associated macrophages (TaMs). The key points section summarizes the study design and major findings, while the main message section highlights the significance of the results and their implications for public health.

Key Points:

* The study uses an immunocompetent mouse model with orthotopic implantation of breast cancer cells to examine the effects of e-cigarette exposure on tumor growth.
* The study also uses in vitro models to examine the impact of e-cigarette exposure on breast cancer cell migration and the interaction between breast cancer cells and TaMs.
* The study finds that e-cigarette exposure promotes tumor growth and metastasis by increasing the infiltration of TaMs, upregulating the expression of pro-tumorigenic factors, and enhancing the binding of TaMs to breast cancer cells.
* The study also identifies the CCL5/CCR1/CCR5 axis as a potential mechanism for e-cigarette-induced tumor progression and metastasis.
* The study uses an in vivo inhibition study with Maraviroc, a specific small molecule inhibitor of the CCR5 chemokine receptor, to further confirm the role of the CCL5/CCR1/CCR5 axis in e-cigarette-induced tumor progression and metastasis.
* The study also identifies nicotine aerosol and/or its derivatives generated from the aerosolization as a potential active component responsible for the biological effect of e-cigarette vapor condensate (EVC) in EpRaS cells.
* The study highlights the need for further research to identify specific components in the complex composition of EVC after the aerosolization.

Main Message:
The study provides strong evidence for the involvement of e-cigarette exposure in enhancing breast cancer progression and pulmonary metastasis. The study highlights the potential serious and avoidable risks associated with vaping and informs therapeutic approaches in breast cancers with high risk for metastasis. The study also underscores the need for further research to identify the active component(s) in e-cigarette vapor and their mechanisms of action. The results of this study have important implications for public health, particularly for the growing population of e-cigarette users, and highlight the need for regulation and education to mitigate the potential risks associated with e-cigarette use.

Pham K, huynh D, Le L, et al. E-cigarette promotes breast carcinoma progression and lung metastasis: Macrophage-tumor cells crosstalk and the role of CCL5 and VCaM-1. Cancer letters. 2020;491:132-145. doi:10.1016/j.canlet.2020.08.010