Calcitriol in the Presence of Conditioned Media from Metastatic Breast Cancer Cells Enhances Ex Vivo Polarization of M2 Alternative Murine Bone Marrow-Derived Macrophages

• Main Authors: Artur Anisiewicz, Natalia Łabędź, Izabela Krauze, Joanna Wietrzyk
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Cancers
• Subjects: macrophages; BMDMs; vitamin D; calcitriol; breast cancer cells; M2 macrophages
• Online Access: https://www.mdpi.com/2072-6694/12/11/3485

In this study, we differentiated murine bone marrow-derived macrophages (BMDMs) into M0, M1, and M2 in the presence or absence of calcitriol. Real-time PCR analysis of gene expression, FACS analysis of surface markers, and chemokine/cytokine production assays were performed. In addition, the effect of the conditioned media (CM) from murine breast cancer 4T1 (metastatic) and 67NR (non-metastatic) and Eph4-Ev (normal) cells with and without calcitriol on the polarization of M1/M2 cells was determined. We found that calcitriol enhanced the differentiation of M2 macrophages, which was manifested by increased expression of <i>Cd206</i> and <i>Spp1</i> mRNA and CD36, Arg, and CCL2 in M2 BMDMs and by decreased expression of <i>Cd80</i> and <i>Spp1</i> mRNA and IL-1, IL-6, OPN, and iNOS in M1 BMDMs. 4T1 CM showed a higher effect on the gene and protein expression in macrophages than 67NR and Eph4-Ev, with the greatest effect observed on M2 macrophages which increased their differentiation and properties characteristic of alternative macrophages. Moreover, M2 macrophages differentiated with calcitriol-stimulated migration of 4T1 and 67NR cells through fibronectin and collagen type IV, respectively. Overall, our results indicated that vitamin D supplementation may not always be beneficial, especially in relation to cancers causing excessive, pathological activation of the immune system.