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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ICOS but not CD28 stimulation generates memory Th17 cells with superior ...

Figure 1

ICOS but not CD28 stimulation generates memory Th17 cells with superior antitumor activity.

(A) Th17 cells costimulated with ICOS regress melanoma to a greater extent than CD28-stimulated Th17 cells. C57BL/6 mice bearing large subcutaneously B16F10 melanoma tumors established for 10 days received nonmyeloablative 5 Gy total body irradiation. One day later, mice received an ACT treatment regimen consisting of the adoptive transfer of 1 × 106 cultured tumor-reactive TRP-1 CD4+ T cells programmed to a Th17 phenotype (with IL-β, IL-21, IL-6, TGF-β, anti-IL-4, and anti-IFN-γ) and expanded for 7 days with beads coated with CD3 agonist and with either a CD28 or ICOS agonist. Tumor growth was measured every 2 to 3 days; n = 8 mice/group. Data (mean ± SEM) are representative of 2 independent experiments. Mean tumor areas compared by 1-way ANOVA with multiple comparisons; **P < 0.01, ***P < 0.001. (B) Th17 cells primed with ICOS but not CD28 persist in vivo for 200 days. Quantification of tumor-specific (Vβ14+CD45.2+) TRP-1 Th17 cells expanded with ICOS versus CD28 from lymph nodes, lungs, and spleen of CD45.1+ recipient mice 200 days after transfer. Percentage frequencies compared by Student’s t test; *P < 0.05, **P < 0.01. (C) ICOS-stimulated CD45.2+ Th17 cells secrete more IFN-γ, IL-17A, and IL-21 than CD28-stimulated Th17 cells when reactivated ex vivo. Donor CD45.2+ Th17 cells were isolated from CD45.1+ recipient mouse spleens 200 days after transfer and then reactivated with irradiated spenotyces pulsed with TRP-1 peptide. IFN-γ, IL-21, and IL-17A production was then measured using flow cytometry. Percentage frequencies compared by Student’s t test; *P < 0.05. (D) Th17 cells stimulated with ICOS possess a durable memory response to tumors after rechallenge with B16F10 tumor. 200 days after initial transfer, surviving mice previously treated with TRP-1 Th17 cells activated with ICOS or CD28 were rechallenged with B16F10 and monitored for tumor burden compared with mice not previously treated (i.e., no treatment). Mantel-Cox curves compared by log-rank test, ***P < 0.001.