Journal: Cell Research
Article Title: Targeting PTPN13 with 11-amino-acid peptides of C-terminal APC prevents immune evasion of colorectal cancer
doi: 10.1038/s41422-025-01206-4
Figure Lengend Snippet: a Flag-tagged Stat1 expression vector (0.5 μg) was transfected into CT26 cells. Total cell lysates were immunoprecipitated with anti-Flag and immunoblotted with anti-PTPN13. b Schematic diagram showing the GST-fused PTPN13 motifs and His-tagged STAT1 used in the GST pull-down assays. c GST pull-down assays examining the interactions between GST-fused PTPN13 fragments and His-tagged STAT1 protein. Data are representative of three independent experiments. d Phosphorylated STAT1 was immunoprecipitated with anti-Flag from IFNγ-stimulated 293T transfectants and incubated with 0.2 mg/mL recombinant GST-PTPase domain of PTPN13. Immunoprecipitates were immunoblotted with anti-phospho-STAT1. Equal loading was verified by reprobing with anti-STAT1. e Total cell lysates of CT26 cells were immunoprecipitated with anti-APC and immunoblotted with anti-PTPN13. Data are representative of three independent experiments. f CT26 cells were treated with the indicated concentrations of IFNγ, and cell lysates were immunoprecipitated with anti-APC and immunoblotted with anti-PTPN13. g A Flag-tagged Stat1 vector (0.5 μg) was transfected into CT26-shApc cells or their control cells. Total cell lysates from the indicated cells were immunoprecipitated with anti-Flag and immunoblotted with anti-PTPN13. Data are representative of three independent experiments. h Alphafold3-predicted binding pattern of human APC (brown) and the PDZ2a domain of PTPN13 (cyan). The APC V2843 residue is labeled, and APC Q2829–V2843 residues are shown as sticks and colored in yellow. Hydrogen bonds are shown as yellow dotted lines. i CT26 cells were transfected with HA-tagged Apc-WT or Apc V2860A mutant plasmids, and total cell lysates were immunoprecipitated with anti-HA and immunoblotted with anti-PTPN13 and anti-CTNNB1. Data are representative of three independent experiments. j IFNγ (50 ng/mL) was administered to CT26 cells transfected with Apc-WT or Apc V2860A mutant plasmids for 12 h, and Apc, Lgr5, Axin2, Irf1, Lmp2, Tap1, Tap2, H2-D1, H2K1 , and B2m mRNA expression was detected by RT-qPCR. Data are representative of three independent experiments. One-way ANOVA. k CRISPR/Cas9-based establishment of APC V2860A point mutation. l CT26 cells transfected with APC-WT or APC V2860A mutant plasmids (CT26-APC V2860A -1/2) were incubated with or without IFNγ at the indicated concentrations for 2 h, and total cell lysates were subjected to immunoblot analysis. m IFNγ (50 ng/mL) was administered to CT26 cells transfected with Apc-WT or Apc V2860A mutant plasmids (CT26-APC V2860A -1/2) for 12 h, and Apc, Lgr5, Axin2, Irf1, Lmp2, Tap1, Tap2, H2-D1, H2K1 , and B2m mRNA expression was detected by RT-qPCR. Data are representative of three independent experiments. One-way ANOVA. n CT26 cells harboring gRNA-induced mutant APC V2860A (CT26-APC V2860A -1/2) and the WT control were subcutaneously injected (2 × 10 6 cells) into Balb/c mice, and tumor growth was monitored. n = 8 for each group, two-way ANOVA. o Immunofluorescence of CD8 + cell infiltration in subcutaneous tumors of CT26-APC V2860A and the control group. n = 8 for each group, one-way ANOVA. Data are representative of three independent experiments. All data are mean ± SEM, * P < 0.05, ** P < 0.01, *** P < 0.001.
Article Snippet: Staining for (CK, CD3 and CD8) or (Epcam, HLA-ABC and CD8) or (APC, PTPN13 and p-STAT1) was performed using a sequential multiplexed immunofluorescence protocol with the isotype-specific primary antibodies anti-CK (1:800, #C2562, Sigma-Aldrich), Epcam (1:500, #93790S, Cell Signaling Technology), CD3E (1:500, #HPA043955, ATLAS), CD8 (1:500, #HPA037756, ATLAS), HLA-ABC (1:200, #565292, BD Biosciences), APC (1:100, #ab15270, abcam), PTPN13 (1:500, #NB100-56139, Novus) and p-STAT1 (1:50, #9167S, Cell Signaling Technology).
Techniques: Expressing, Plasmid Preparation, Transfection, Immunoprecipitation, Incubation, Recombinant, Control, Binding Assay, Residue, Labeling, Mutagenesis, Quantitative RT-PCR, CRISPR, Western Blot, Injection, Immunofluorescence