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Pharmacological inhibition of β-catenin/BCL9 interaction overcomes resistance to immune checkpoint blockades by modulating Treg cells

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Science Advances  08 May 2019:
Vol. 5, no. 5, eaau5240
DOI: 10.1126/sciadv.aau5240
  • Fig. 1 In vitro profiling of hsBCL9CT-24.

    (A) Customized ALPHA assay detecting protein binding interactions between biotinylated hsBCL9CT-24 and His-tagged β-cat. RLU, relative luciferase units. (B) Docking hsBCL9CT-24 into the β-cat hydrophobic pocket (Protein Data Bank: 3SL9) performed by GlideXP Maestro Schrodinger. In the left panel, green labels represent hydrophobic binding sites, while white labels denote hydrophilic amino acids. In the right panel, white labels illustrate amino acids in the β-cat hydrophobic pocket. (C) β-cat reporter assay conducted in LEF/TCF-bla HCT116 cells (Ser45 deletion in one allele of the CTNNB1 gene) treated with hsBCL9CT-24 (IC50 = 191 nM). (D) Table summarizing reporter assay results, denoting hsBCL9CT-24’s specificity in Wnt/β-cat inhibition (IC50 = 191 nM) and lack of off-target effects in other signaling cascades (IC50 > 1000 nM for all). (E) Dose-response curves showing inhibitory effects of the indicated molecules on growth of the Colo320DM cell line: hsBCL9CT-24 (IC50 = 1.45 μM) compared to ICG-001 (IC50 = 15.03 μM), LGK-974 (IC50 = 18.46 μM), and erlotinib (IC50 = 10 μM). (F) Dose-response curves showing Colo320DM cells treated with 5-fluorouracil (5-FU) or 5-FU combined with 2 μM hsBCL9CT-24. Addition of 2 μM hsBCL9CT-24 lowered the IC50 of 5-FU from 12.1 μM to 1 μM. **P < 0.01, two-way analysis of variance (ANOVA). (G) BrdU cell proliferation assay of colon cancer lines (LS174T, HCT116D, SW48, and Colo320DM) and breast cancer cell lines (MDA231 and MCF7) treated with 8 μM hsBCL9CT-24 over 24 hours. *P < 0.05, **P < 0.01, unpaired Student’s t test. Results were denoted as means ± SEM for assays performed in triplicate and repeated twice.

  • Fig. 2 hsBCL9CT-24 inhibits tumor growth and Wnt pathway activity in multiple CRC mouse models.

    (A) Dose-escalation study of hsBCL9CT-24 treatment in the Colo320DM xenograft model. Four cohorts of female BALB/c nude mice (n = 4 per cohort) were administered vehicle control or hsBCL9CT-24 (5, 10, or 15 mg/kg) via i.v. injection, QD over 14 days. Tumor sizes are displayed as means ± SEM (**P < 0.01). (B) Quantitative reverse transcription polymerase chain reaction (qRT-PCR) measurement of CD44 and VEGF in the Colo320DM tumors following hsBCL9CT-24 treatment (**P < 0.01). (C) Representative images of immunohistochemistry (IHC) staining for β-cat and BCL9 in a CRC patient-derived tumor tissue. H&E, hematoxylin and eosin. (D) Tumor samples in (C) were inoculated in NOD/SCID mice and treated with vehicle control or hsBCL9CT-24 at 15 mg/kg via i.p. injection, QD for 31 days (n = 8 per cohort, **P < 0.01). (E) Representative images of IHC staining for CD44 expression in the tumors from (D). Scale bar, 100 μm. (F) CT26 cells were inoculated in BALB/c nude mice before treatment with vehicle control or hsBCL9CT-24 (n = 6 per cohort) at 25 mg/kg via i.p. injection, QD for 5 days (**P < 0.01). (G) CT26 cells were inoculated in BALB/c mice before treatment with vehicle control or hsBCL9CT-24 at 25 mg/kg via i.p. injection (n = 6 per cohort), QD for 6 days (***P < 0.001). (H) CT26 cells transduced with nontargeting (NT) shRNA or β-cat shRNA were inoculated in BALB/c mice (n = 8 per cohort, ***P < 0.001); day 0 started from 10 days after tumor inoculation. (I) CT26 cells were inoculated in BALB/c mice and treated with either vehicle control, hsBCL9CT-24, or ICG-001 at 25 mg/kg via i.p. injection, erlotinib (25 mg/kg) via oral QD, or oxaliplatin (5 mg/kg) via i.p. and QD over 12 days (n = 4 per cohort, **P < 0.01). Results were denoted as means ± SEM for experiments performed in triplicate, and each experiment was repeated twice. Statistical significance of differences between groups was determined by two-way ANOVA for all tumor growth assays.

  • Fig. 3 Activation of the Wnt pathway is associated with Treg cell infiltration in human CRC.

    The correlation between infiltration of (A) CD8+ T cells, (B) activated DCs, and (C) Treg cells and APC gene mutation status in human CRC samples was analyzed by CIBERSORT (*P < 0.05). (D) Relative heat map of expression correlation between CD4, CD25, and FOXP3 with a subset of Wnt pathway genes in 287 colon cancer tumors. (E) Relative heat map of Wnt pathway gene expression in colon cancer tumors stratified by Treg cell infiltration level [Treg-hi (CD4-hi CD25-hi FOXP3-hi) versus Treg-lo (CD4-lo CD25-lo FOXP3-lo)]. High infiltration is denoted by the top quartile, while low infiltration is composed of the bottom quartile of the 287 tumors. Each column represents one sample, with samples arranged according to FOXP3 expression level. (F) IHC staining for β-cat, FOXP3, and CD8 in two representative human CRC samples.

  • Fig. 4 hsBCL9CT-24 reduces Treg cell infiltration by inhibition of CCL20 and CCL22 in cancer.

    (A) BALB/c mice inoculated with CT26 tumors were treated with vehicle control or hsBCL9CT-24 (20 mg/kg) via i.p. injection, QD over 14 days. Representative flow panels of CD4+CD25+FOXP3+ T cells (Treg) are shown. (B) Ratio of CD4+CD25+FOXP3+ cells among the CD45+ cell populations in the tumors from (A) (***P < 0.001). Mice bearing (C) LLC1 tumors or (D) 4T1 tumors were treated with vehicle control or hsBCL9CT-24 (20 mg/kg) via i.p. injection, QD over 14 days. Percentages of CD25+FOXP3+ Treg cells among the CD45+ cell populations in the respective tumors are shown (***P < 0.001). (E) Migration of freshly isolated Treg cells cocultured with CT26 cells pretreated with or without hsBCL9CT-24 (5 μM) for 24 hours (*P < 0.05). (F) Migration of freshly isolated Treg cells cocultured with CT26 cells transduced with NT shRNA or β-cat shRNA (*P < 0.05). WT, wild type. (G) qRT-PCR measurement of CCL20 (*P < 0.05), CCL22 (**P < 0.01), and TGFB1 (*P < 0.05) in CT26 cells treated with or without hsBCL9CT-24 (5 μM) for 24 hours. (H) qRT-PCR measurement of CCL22 (*P < 0.05), CTNNB1 (***P < 0.001), and TGFB1 (**P < 0.01) expression in CT26 cells transduced with NT shRNA or β-cat shRNA. Results were denoted as means ± SEM for experiments performed in triplicate. Each experiment was repeated twice, and the statistical significance of differences between groups was determined by unpaired Student’s t test.

  • Fig. 5 hsBCL9CT-24 reactivates anticancer immunity and overcomes resistance to PD-1 inhibitors.

    (A) BALB/c mice inoculated with CT26 tumors were treated with vehicle control or hsBCL9CT-24 (20 mg/kg) via i.p. injection, QD over 14 days (n = 4 per cohort). The percentage of CD103+ cells among CD45+CD11c+ DC cells in tumor was analyzed (**P < 0.01). (B) Percentage of CD103+ cells among CD45+CD11c+ DC cells in wild-type (transduced without shRNA), NT shRNA, or β-cat shRNA transduced CT26 tumors (*P < 0.05, **P < 0.01). (C) qRT-PCR measurement of CCL4 expression in CT26 cells treated with vehicle or hsBCL9CT-24 at 5 μM for 24 hours (**P < 0.01). (D) qRT-PCR measurement of CCL4 expression in CT26 cells transduced with NT shRNA or β-cat shRNA (**P < 0.01). (E) Fluorescence-activated cell sorting analysis of the ratio of CD8+ to CD45+ T cells in the tumors described in (A). (F) Ratio of CD8+ cytotoxic T cells over Treg cells in the tumors described in (A) (**P < 0.01). (G) Fold change of granzyme B+CD8+ T cells among the overall CD8+ T cell population before and after hsBCL9CT-24 treatment (**P < 0.01). (H) Fold change of granzyme B+CD8+ T cells among overall CD8+ T cell population in CT26 WT, NT shRNA, and β-cat shRNA transduced tumors (**P < 0.01). (I) Fold change of CD8+CD44+CD62L cells (effector CD8+ cells) among the overall CD8+ T cell population before and after hsBCL9CT-24 treatment (**P < 0.01). (J) Fold change of effector CD8+ cells among the overall CD8+ T cell population in CT26 WT, NT shRNA, and β-cat shRNA transduced tumors (**P < 0.01). Statistical significance of differences between groups was determined by unpaired Student’s t test. (K) Combination treatment of hsBCL9CT-24 and anti–PD-1 Ab resulted in almost complete regression in the LLC1 model. C57BL/6 mice were inoculated with LLC1 cells via single flank implantation and treated with immunoglobulin G (IgG), hsBCL9CT-24 (25 mg/kg, QD), anti–PD-1 Ab [twice weekly (BIW)], and hsBCL9CT-24 + anti–PD-1 Ab as indicated after tumor volume reached 30 mm3 (n = 4 per cohort) (**P < 0.01). (L) Combination treatment of hsBCL9CT-24 and anti–PD-1 Ab resulted in significant tumor reduction in the 4T1 model. BALB/c mice were inoculated with 4T1 cells via mammary gland inoculation and treated with IgG, hsBCL9CT-24 (20 mg/kg) QD, anti–PD-1 Ab, BIW, and hsBCL9CT-24 + anti–PD-1 Ab as indicated after tumor volume reached 20 mm3 (n = 4 per cohort) (**P < 0.01). Statistical significance of differences in tumor growth assays was determined by two-way ANOVA. Results were denoted as means ± SEM for experiments performed in triplicate, and each experiment was repeated twice.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/5/eaau5240/DC1

    Supplementary Materials and Methods

    Fig. S1. Biochemical profile and LC-MS analysis of hsBCL9CT peptides.

    Fig. S2. Cellular uptake, Wnt reporter, and coimmunoprecipitation analysis of hsBCL9CT peptides.

    Fig. S3. Selectivity in multiple signaling pathways and antiproliferation assay of hsBCL9CT peptides.

    Fig. S4. PK, toxicology, and histology analysis of hsBCL9CT-24 and hsBCL9CT-35.

    Fig. S5. IHC staining in patient tumor tissues and PDX tumor models.

    Fig. S6. Wnt pathway gene expression is correlated with CD4+CD25+FOXP3+ Treg cell infiltration in cancers.

    Fig. S7. Effects of hsBCL9CT-24 treatment on anticancer immune cells.

    Table S1. Sequences of hsBCL9CT peptides and related derivatives.

    Table S2. PK and TK profiles of hsBCL9CT-24 and hsBCL9CT-35 in mice.

    Table S3. Additional PK, solubility, and stability investigations with hsBCL9CT-24.

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Materials and Methods
    • Fig. S1. Biochemical profile and LC-MS analysis of hsBCL9CT peptides.
    • Fig. S2. Cellular uptake, Wnt reporter, and coimmunoprecipitation analysis of hsBCL9CT peptides.
    • Fig. S3. Selectivity in multiple signaling pathways and antiproliferation assay of hsBCL9CT peptides.
    • Fig. S4. PK, toxicology, and histology analysis of hsBCL9CT-24 and hsBCL9CT-35.
    • Fig. S5. IHC staining in patient tumor tissues and PDX tumor models.
    • Fig. S6. Wnt pathway gene expression is correlated with CD4+CD25+FOXP3+ Treg cell infiltration in cancers.
    • Fig. S7. Effects of hsBCL9CT-24 treatment on anticancer immune cells.
    • Table S1. Sequences of hsBCL9CT peptides and related derivatives.
    • Table S2. PK and TK profiles of hsBCL9CT-24 and hsBCL9CT-35 in mice.
    • Table S3. Additional PK, solubility, and stability investigations with hsBCL9CT-24.

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