Tumor-derived microRNAs induce myeloid suppressor cells and predict immunotherapy resistance in melanoma
Veronica Huber, … , Monica Rodolfo, Licia Rivoltini
Veronica Huber, … , Monica Rodolfo, Licia Rivoltini
Published September 27, 2018
Citation Information: J Clin Invest. 2018;128(12):5505-5516. https://doi.org/10.1172/JCI98060.
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Research Article Immunology Oncology

Tumor-derived microRNAs induce myeloid suppressor cells and predict immunotherapy resistance in melanoma

Abstract

The accrual of myeloid-derived suppressor cells (MDSCs) represents a major obstacle to effective immunotherapy in cancer patients, but the mechanisms underlying this process in the human setting remain elusive. Here, we describe a set of microRNAs (miR-146a, miR-155, miR-125b, miR-100, let-7e, miR-125a, miR-146b, miR-99b) that are associated with MDSCs and resistance to treatment with immune checkpoint inhibitors in melanoma patients. The miRs were identified by transcriptional analyses as being responsible for the conversion of monocytes into MDSCs (CD14+HLA-DRneg cells) mediated by melanoma extracellular vesicles (EVs) and were shown to recreate MDSC features upon transfection. In melanoma patients, these miRs were increased in circulating CD14+ monocytes, plasma, and tumor samples, where they correlated with the myeloid cell infiltrate. In plasma, their baseline levels clustered with the clinical efficacy of CTLA-4 or programmed cell death protein 1 (PD-1) blockade. Hence, MDSC-related miRs represent an indicator of MDSC activity in cancer patients and a potential blood marker of a poor immunotherapy outcome.

Authors

Veronica Huber, Viviana Vallacchi, Viktor Fleming, Xiaoying Hu, Agata Cova, Matteo Dugo, Eriomina Shahaj, Roberta Sulsenti, Elisabetta Vergani, Paola Filipazzi, Angela De Laurentiis, Luca Lalli, Lorenza Di Guardo, Roberto Patuzzo, Barbara Vergani, Elena Casiraghi, Mara Cossa, Ambra Gualeni, Valentina Bollati, Flavio Arienti, Filippo De Braud, Luigi Mariani, Antonello Villa, Peter Altevogt, Viktor Umansky, Monica Rodolfo, Licia Rivoltini

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Figure 4

Inhibition of MDSC-miRs rescues monocytes from the acquisition of a suppressive phenotype.

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Inhibition of MDSC-miRs rescues monocytes from the acquisition of a supp...
(A) Effect of transfection with miR inhibitors or scrambled control (Scr) on MDSC-miR expression in INT12 melanoma cells and respective EVs (left panel). Reduced expression of miR-146a in silenced melanoma cells (Me) was confirmed by flow cytometry using an APC-fluorescent SmartFlare probe (right panel). (B) EVs derived from miR-silenced melanoma cells (+I-EVs) impaired the induction of the EV-MDSC phenotype compared with EVs derived from scrambled control cells (+S-EVs) (left panel); MDSC-miR expression was reduced in monocytes treated with I-EVs compared with those treated with S-EVs (right panel). (C) Effect of transfection with miR inhibitors or scrambled control of HD monocytes cultured in the presence of melanoma EVs, as evaluated by qPCR and flow cytometry, and (D) IL-6 and CCL2 release. (E) Loss of immunosuppressive activity of EV-MDSCs, generated from HD in the presence of miR inhibitors or scrambled control, on activated CFSE-labeled T cells, as evaluated by flow cytometry (left panel) and cytokine release (right panel), and (F) loss of immunosuppressive activity of EV-MDSCs generated from a patient with autologous melanoma–derived EVs. Percentages of CD25 and CFSE expression are indicated. Cells transfected with scrambled control were used as a calibrator (A–C). P < 0.05, paired Student’s t test (A–C); P < 0.001, 1-way ANOVA (D). *P < 0.05, **P < 0.01, paired Student’s t test (E, F). Experiments were repeated twice and performed in triplicate (A–D, F). Data are representative of 2 HD tested (E).