Targeting miR-23a in CD8+ cytotoxic T lymphocytes prevents tumor-dependent immunosuppression
Regina Lin, Ling Chen, Gang Chen, Chunyan Hu, Shan Jiang, Jose Sevilla, Ying Wan, John H. Sampson, Bo Zhu, Qi-Jing Li
Regina Lin, Ling Chen, Gang Chen, Chunyan Hu, Shan Jiang, Jose Sevilla, Ying Wan, John H. Sampson, Bo Zhu, Qi-Jing Li
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Research Article Oncology

Targeting miR-23a in CD8+ cytotoxic T lymphocytes prevents tumor-dependent immunosuppression

Abstract

CD8+ cytotoxic T lymphocytes (CTLs) have potent antitumor activity and therefore are leading candidates for use in tumor immunotherapy. The application of CTLs for clinical use has been limited by the susceptibility of ex vivo–expanded CTLs to become dysfunctional in response to immunosuppressive microenvironments. Here, we developed a microRNA-targeting (miRNA-targeting) approach that augments CTL cytotoxicity and preserves immunocompetence. Specifically, we screened for miRNAs that modulate cytotoxicity and identified miR-23a as a strong functional repressor of the transcription factor BLIMP-1, which promotes CTL cytotoxicity and effector cell differentiation. In a cohort of advanced lung cancer patients, miR-23a was upregulated in tumor-infiltrating CTLs, and expression correlated with impaired antitumor potential of patient CTLs. We determined that tumor-derived TGF-β directly suppresses CTL immune function by elevating miR-23a and downregulating BLIMP-1. Functional blocking of miR-23a in human CTLs enhanced granzyme B expression, and in mice with established tumors, immunotherapy with just a small number of tumor-specific CTLs in which miR-23a was inhibited robustly hindered tumor progression. Together, our findings provide a miRNA-based strategy that subverts the immunosuppression of CTLs that is often observed during adoptive cell transfer tumor immunotherapy and identify a TGF-β–mediated tumor immune-evasion pathway.

Authors

Regina Lin, Ling Chen, Gang Chen, Chunyan Hu, Shan Jiang, Jose Sevilla, Ying Wan, John H. Sampson, Bo Zhu, Qi-Jing Li

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Figure 8

Adoptive transfer therapy with miR-23a–inhibited CTLs in mouse models of established tumors.

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Adoptive transfer therapy with miR-23a–inhibited CTLs in mouse models of...
Seven days after s.c. inoculation of 0.2 × 106 B16/F10 melanoma or LLC-OVA cells, C57BL/6 tumor-bearing mice were sublethally irradiated and left untreated (PBS), or treated with intratumoral injections of 0.2 × 106 sorted iRFP+GFP+ mock or miR-23a decoy–expressing pMel-1 or OT-I CTLs. Tumors were excised 10 days after T cell transfer, and mock and miR-23a decoy–expressing Thy1.1+ pMel-1 CTLs within the tumor masses were analyzed by flow cytometry. (A) B16/F10 and (D) LLC-OVA tumor progression after the initiation of CTL therapy. Data represent mean ± SEM, from n = 6 mice per group in 1 representative of 3 independent experiments in A, and from n = 10 mice per group in D. *P < 0.05, **P < 0.01, and ***P < 0.001 indicate mock vs. miR-23a decoy; #P < 0.05, ##P < 0.01, and ###P < 0.001 indicate mock vs. PBS by 2-way ANOVA and Bonferroni post-test. (B and C) B16/F10 and (E and F) LLC-OVA tumor sizes and weight 10 days after CTL therapy. (G) Absolute numbers of Thy1.1+ pMel-1 CTLs present in tumors. (H–K) Expression of the CTL master regulators and effector molecules (H) T-bet, (I) EOMES, (J) IFN-γ, and (K) granzyme B in Thy1.1+ pMel-1 CTLs isolated from B16/F10 tumors. Data represent mean ± SEM.