Metformin partially reverses the inhibitory effect of co-culture with ER-/PR-/HER2+ breast cancer cells on biomarkers of monocyte antitumor activity

PLoS One. 2020 Oct 27;15(10):e0240982. doi: 10.1371/journal.pone.0240982. eCollection 2020.

Abstract

Background: Immune activities of monocytes (MOs) can be altered within the microenvironment of solid malignancies, including breast cancer. Metformin (1,1-dimethylbiguanide hydrochloride, MET), has been shown to decrease tumor cell proliferation, but its effects have yet to be explored with respect to MOs (monocytes) activity during their crosstalk with breast cancer cells. Here, we investigated the effects of MET on overall phenotypic functional activities, including cellular immunometabolism and protective redox signaling based-biomarkers, intracellular free calcium ions (ifCa2+), phagocytosis and co-operative cytokines (IFN-γ and IL-10) of autologous MOs before and during their interplay with primary ER-/PR-/HER2+ breast cancer cells.

Methods: Human primary breast cancer cells were either cultured alone or co-cultured with autologous MOs before treatment with MET.

Results: MET downregulated breast cancer cell proliferation and phagocytosis, while having no significant effect on the ratio of phosphorylated Akt (p-Akt) to total Akt. Additionally, we observed that, in the absence of MET treatment, the levels of lactate dehydrogenase (LDH)-based cytotoxicity, catalase, ifCa2+, IL-10 and arginase activity were significantly reduced in co-cultures compared to levels in MOs cultured alone whereas levels of inducible nitric oxide synthase (iNOS) activity were significantly increased. In contrast, MET treatment reduced the effects measured in co-culture on the levels of LDH-based cytotoxicity, arginase activity, catalase, ifCa2+, and IFN-γ. MET also induced upregulation of both iNOS and arginase in MO cells, although the increase did not reach significant difference for iNOS activity. Moreover, MET induced a robust increase of superoxide dismutase (SOD) activity in MOs, but not in MOs co-cultured with breast cancer cells. Furthermore, MET markedly upregulated the levels of IFN-γ production and downregulated those of IL-10 in isolated MOs, while inducing a slight opposing up-regulation of IL-10 production in co-cultures.

Conclusions: Our results show that the biomarkers of phenotypic functional activities of MOs are modified after co-culturing with primary human breast cancer cells. Treatment of co-cultures with MET resulted in increased release of antitumor cytokine IFN-γ and ifCa2+, and increased cell necrosis during breast cancer cells-MOs crosstalk.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomarkers / metabolism*
  • Breast Neoplasms / drug therapy
  • Breast Neoplasms / metabolism*
  • Cell Proliferation / drug effects
  • Cells, Cultured
  • Coculture Techniques
  • Female
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • L-Lactate Dehydrogenase / metabolism
  • Metformin / pharmacology*
  • Monocytes / cytology*
  • Receptor, ErbB-2 / metabolism
  • Receptors, Estrogen / metabolism
  • Receptors, Progesterone / metabolism

Substances

  • Biomarkers
  • Receptors, Estrogen
  • Receptors, Progesterone
  • Metformin
  • L-Lactate Dehydrogenase
  • ERBB2 protein, human
  • Receptor, ErbB-2

Grants and funding

This work was funded by the Thematic Research Agencies ATRBSA and ATRSS (Algeria) and the Directorate General of Scientific Research and Technological Development (DGRSDT, Direction Générale de la Recherché Scientifique et du Développement Technologique, MESRS, Algeria) for financial support to ZD, LA-K, SD, AM, NC-D, MI-B, MM, HT, WN, MM and MA. FG, GL, AF and NL were supported by CNRS core funding and AFD (Association Francaise pour la Diabete) grant 1546. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.