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

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 ( if Ca 2+ ), 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, if Ca 2+ , 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, if Ca 2+ , 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 if Ca 2+ , and increased cell necrosis during breast cancer cells-MOs crosstalk.

Tamoxifen Modulates the Immune Landscape of the Tumour Microenvironment: The Paired Siglec-5/14 Checkpoint in Anti-Tumour Immunity in an In Vitro Model of Breast Cancer

“…Interestingly, the evaluation of the expression of Arg-1 revealed the opposite responses of THP-1 monocytes to external stimuli within the tested co-cultures. The study by Dahmani et al revealed that the phenotypic functional activities of monocytes were modified after co-culturing with primary human breast cancer cells [ 43 ]. In the presence of MCF-7 but not MDA-MB-231 cells, THP-1 cells showed a strong decrease in the expression of Arg-1 when compared with monocytes cultured alone.…”

Metformin Affects Olaparib Sensitivity through Induction of Apoptosis in Epithelial Ovarian Cancer Cell Lines

“…Most patients with high-grade serous EOC exhibit the phenotype of defective HR without BRCA mutations known as “BRCAness” [ 33 ]. Metformin is a low-toxicity therapeutic approach that targets various key pathways and is crucial for cancer treatment [ 34 ]. Metformin has been used for over 60 years, whereas olaparib is a relatively new drug that has been used as part of chemotherapy since the beginning of 2015.…”

“…In clinical trials, PARPis significantly increased the efficacy of standard therapies through combination treatment with carboplatin (NCT01033292), cediranib (NCT02681237), or nivolumab (NCT03522246). In breast cancer cells, metformin induces cell death via PARP activation and apoptosis [ 33 ], and in ovarian cancer, it induces cell death in combination with other drugs such as cisplatin [ 34 , 35 , 36 ].…”

Targeting of the tumor immune microenvironment by metformin

“…Treatment of HER2 + breast cancer cells co‐cultured by monocytes with metformin showed a decline in the IL‐10 release, while stimulates the release of IFN‐γ. However, the levels of Arginase (a marker of TAMs) were upregulated following treatment with metformin (Dahmani et al 2020). Although the modulatory effect of metformin in this study isn't favorable for tumor therapy, we should consider that metformin may affect the expression of iNOS + macrophages in a complete tumor model, because of the release of inflammatory cytokines by CTLs and NK cells.…”