Tumor-associated macrophage derived IL-6 enriches cancer stem cell population and promotes breast tumor progression via Stat-3 pathway

N N V Radharani; Amit S Yadav; Ramakrishna Nimma; T V Santosh Kumar; Anuradha Bulbule; Venkatesh Chanukuppa; Dhiraj Kumar; Srinivas Patnaik; Srikanth Rapole; Gopal C Kundu

doi:10.1186/s12935-022-02527-9

Tumor-associated macrophage derived IL-6 enriches cancer stem cell population and promotes breast tumor progression via Stat-3 pathway

Cancer Cell Int. 2022 Mar 17;22(1):122. doi: 10.1186/s12935-022-02527-9.

Authors

N N V Radharani^#^{1

2}, Amit S Yadav^#^{1

2}, Ramakrishna Nimma¹, T V Santosh Kumar¹, Anuradha Bulbule¹, Venkatesh Chanukuppa³, Dhiraj Kumar⁴, Srinivas Patnaik², Srikanth Rapole³, Gopal C Kundu^{5

6

7}

Affiliations

¹ Laboratory of Tumor Biology, Angiogenesis and Nanomedicine Research, National Centre for Cell Science (NCCS), Pune, 411007, India.
² School of Biotechnology, KIIT Deemed To Be University, Bhubaneswar, 751 024, India.
³ Proteomics Laboratory, National Centre for Cell Science (NCCS), Pune, 411007, India.
⁴ Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77054, USA.
⁵ Laboratory of Tumor Biology, Angiogenesis and Nanomedicine Research, National Centre for Cell Science (NCCS), Pune, 411007, India. gopalc.kundu@kiit.ac.in.
⁶ School of Biotechnology, KIIT Deemed To Be University, Bhubaneswar, 751 024, India. gopalc.kundu@kiit.ac.in.
⁷ Kalinga Institute of Medical Sciences (KIMS), KIIT Deemed To Be University, Bhubaneswar, 751024, India. gopalc.kundu@kiit.ac.in.

^# Contributed equally.

Abstract

Background: Cancer stem cells (CSCs) play crucial role in tumor progression, drug resistance and relapse in various cancers. CSC niche is comprised of various stromal cell types including Tumor-associated macrophages (TAMs). Extrinsic ques derived from these cells help in maintenance of CSC phenotype. TAMs have versatile roles in tumor progression however their function in enrichment of CSC is poorly explored.

Methods: Mouse macrophages (RAW264.7) cells were activated by interaction with conditioned media (CM) of murine breast cancer cells (4T1) into TAMs and the effect of activated macrophage (TAM) derived factors was examined on enrichment of cancer stem cells (CSCs) and tumor growth using in vitro and in vivo models.

Results: In this study, we report that macrophages upon interaction with breast cancer cells activate tumor promoting function and exhibit differential expression of various proteins as shown by secretome analysis using proteomics studies. Based on secretome data, we found that Interleukin-6 (IL-6) is one of the up-regulated genes expressed in activated macrophages. Further, we confirm that TAMs produce high levels of IL-6 and breast cancer cell derived factors induce IL-6 production in activated macrophages via p38-MAPK pathway. Furthermore, we demonstrate that tumor activated macrophages induce enrichment of CSCs and expression of CSC specific transcription factors such as Sox-2, Oct-3/4 and Nanog in breast cancer cells. We further prove that TAM derived IL-6 plays a key role in TAM mediated CSC enrichment through activation of Signal transducer and activator of transcription 3 (STAT-3) signaling. TAM derived IL-6 influences breast cancer cell migration and angiogenesis. Moreover, our in vivo findings indicated that TAM derived IL-6 induces CSC population and resulting tumor growth in breast cancer.

Conclusion: These finding provide evidence that TAM derived IL-6 plays a major role in CSC enrichment and tumor progression in breast cancer and IL-6 and its regulated signalling network may act as potential therapeutic target for management of breast cancer.

Keywords: Breast cancer progression; Cancer stem cells; IL-6; Tumor-associated macrophages.