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Breast cancer metastasis to brain results in recruitment and activation of microglia through annexin-A1/formyl peptide receptor signaling

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posted on 03.05.2022, 06:55 by SL Foo, K Sachaphibulkij, CLY Lee, GLR Yap, J Cui, Thiruma ArumugamThiruma Arumugam, LHK Lim
Background: Despite advancements in therapies, brain metastasis in patients with triple negative subtype of breast cancer remains a therapeutic challenge. Activated microglia are often observed in close proximity to, or within, malignant tumor masses, suggesting a critical role that microglia play in brain tumor progression. Annexin-A1 (ANXA1), a glucocorticoid-regulated protein with immune-regulatory properties, has been implicated in the growth and metastasis of many cancers. Its role in breast cancer-microglia signaling crosstalk is not known. Methods: The importance of microglia proliferation and activation in breast cancer to brain metastasis was evaluated in MMTV-Wnt1 spontaneous mammary tumor mice and BALBc mice injected with 4T1 murine breast cancer cells into the carotid artery using flow cytometry. 4T1 induced-proliferation and migration of primary microglia and BV2 microglia cells were evaluated using 2D and coculture transwell assays. The requirement of ANXA1 in these functions was examined using a Crispr/Cas9 deletion mutant of ANXA1 in 4T1 breast cancer cells as well as BV2 microglia. Small molecule inhibition of the ANXA1 receptor FPR1 and FPR2 were also examined. The signaling pathways involved in these interactions were assessed using western blotting. The association between lymph node positive recurrence-free patient survival and distant metastasis-free patient survival and ANXA1 and FPR1 and FPR2 expression was examined using TCGA datasets. Results: Microglia activation is observed prior to brain metastasis in MMTV-Wnt1 mice with primary and secondary metastasis in the periphery. Metastatic 4T1 mammary cancer cells secrete ANXA1 to promote microglial migration, which in turn, enhances tumor cell migration. Silencing of ANXA1 in 4T1 cells by Crispr/Cas9 deletion, or using inhibitors of FPR1 or FPR2 inhibits microglia migration and leads to reduced activation of STAT3. Finally, elevated ANXA1, FPR1 and FPR2 is significantly associated with poor outcome in lymph node positive patients, particularly, for distant metastasis free patient survival. Conclusions: The present study uncovered a network encompassing autocrine/paracrine ANXA1 signaling between metastatic mammary cancer cells and microglia that drives microglial recruitment and activation. Inhibition of ANXA1 and/or its receptor may be therapeutically rewarding in the treatment of breast cancer and secondary metastasis to the brain.

Funding

This study was provided by grants from the Ministry of Education in Singapore (MOE2014-T2-1-133 and MOE2017-T2-2-044) awarded to L.H.K.L., G.L.R.Y. and S.L.F and was supported by scholarships from the NUS Graduate School of Science and Technology.

History

Publication Date

01/12/2022

Journal

Breast Cancer Research

Volume

24

Issue

1

Article Number

ARTN 25

Pagination

17p.

Publisher

BMC

ISSN

1465-5411

Rights Statement

© The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.