β-catenin and PI3Kδ inhibition expands precursor Th17 cells with heightened stemness and antitumor activity
Kinga Majchrzak ... Sherine S.L. Chan, Chrystal M. Paulos
Kinga Majchrzak ... Sherine S.L. Chan, Chrystal M. Paulos
Published April 20, 2017
Citation Information: JCI Insight. 2017;2(8):e90547. doi:10.1172/jci.insight.90547.
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Categories: Research Article Immunology Oncology

β-catenin and PI3Kδ inhibition expands precursor Th17 cells with heightened stemness and antitumor activity

Abstract

ICOS costimulation generates Th17 cells with durable memory responses to tumor. Herein, we found that ICOS induces PI3K/p110δ/Akt and Wnt/β-catenin pathways in Th17 cells. Coinhibiting PI3Kδ and β-catenin altered the biological fate of Th17 cells. Th17 cells inhibited of both pathways expressed less RORγt, which, in turn, reduced their ability to secrete IL-17. Unexpectedly, these cells were more effective (than uninhibited cells) at regressing tumor when infused into mice, leading to long-term curative responses. PI3Kδ inhibition expanded precursor Th17 cells with a central memory phenotype that expressed nominal regulatory properties (low FoxP3), while β-catenin inhibition enhanced Th17 multifunctionality in vivo. Remarkably, upon TCR restimulation, RORγt and IL-17 rebounded in Th17 cells treated with PI3Kδ and β-catenin inhibitors. Moreover, these cells regained β-catenin, Tcf7, and Akt expression, licensing them to secrete heightened IL-2, persist, and eradicate solid tumors without help from endogenous NK and CD8 T cells. This finding shines a light on ways to repurpose FDA-approved drugs to augment T cell–based cancer immunotherapies.

Authors

Kinga Majchrzak, Michelle H. Nelson, Jacob S. Bowers, Stefanie R. Bailey, Megan M. Wyatt, John M. Wrangle, Mark P. Rubinstein, Juan C. Varela, Zihai Li, Richard A. Himes, Sherine S.L. Chan, Chrystal M. Paulos

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Wnt/β-catenin and cytokines rebound in dual-inhibited antitumor Th17 cel...

Figure 8

Wnt/β-catenin and cytokines rebound in dual-inhibited antitumor Th17 cells.

(A) β-Catenin accumulates in the nuclei of ICOS-simulated Th17 cells expanded in the presence of CAL-101, whereas indomethacin (Indo) impairs β-catenin translocation to the nucleus. Western blot analysis of nuclear β-catenin and Histone-3 (loading control) expression in ICOS-stimulated Th17 cells expanded in the presence or not of CAL-101 and/or Indo (day 8). (B) Wnt/β-catenin pathway–associated genes are upregulated upon secondary stimulation with peptide in ICOS-activated Th17 cells primed with CAL-101 and/or Indo. Real-time PCR analysis of fold change of gene expression of Tcf7, Lef1, and Ctnnb1 in Th17 cells expanded with inhibitors, as indicated and restimulated in vitro with anti-CD3 antibody (5 μg/ml for 1 hour). Student’s t test; *P < 0.05, **P < 0.01. Fold change was calculated using the ΔΔCT method. (C and D) Western blot analysis of nuclear β-catenin, RORγt, STAT3, Tcf7, and Histone-3 (loading control) expression. Nuclear β-catenin, RORγt, and STAT3 are restored and Tcf7 expression is upregulated after in vitro restimulation of ICOS-activated Th17 cells primed in the presence of inhibitors, as indicated. (E) IL-17 rebounds and IL-2 is elevated in Th17 inhibited cells after secondary stimulation with tumor-specific tyrosinase peptide (2 days after reactivation, ELISA of IL-17A and IL-2). Representative of 3 independent experiments. Student’s t test; *P < 0.05.