Journal: Cancer Research
Article Title: SPP1 Drives Colorectal Cancer Liver Metastasis and Immunotherapy Resistance by Stimulating CXCL12 Production in Cancer-Associated Fibroblasts
doi: 10.1158/0008-5472.CAN-24-4916
Figure Lengend Snippet: SPP1 activates the β-catenin/HIF1α axis in the CAFs to drive CXCL12 secretion. A, Western blotting assessed key signaling pathway in CAFs after 24 hours of SPP1 protein stimulation. B–E, β-catenin and HIF1α expressions were analyzed following SPP1 or conditioned medium treatments, including from SPP1-overexpressing or -knockdown cells. F–H, HIF1α degradation was evaluated with MSAB or si-CTNNB1 transfection after cycloheximide (CHX) treatment, and HIF1α levels were measured after MSAB (1 µmol/L) or MG132 (20 µmol/L) pretreatment. I and J, Coimmunoprecipitation examined the HIF1α and β-catenin interaction. K and L, Immunofluorescence and nuclear–cytoplasmic fractionation assays assessed HIF1α and β-catenin localization ( n = 3). Scale bar, 25 μm. M–O, CXCL12 levels in conditioned media were measured after SPP1 (1 µg/mL) or MSAB treatments (24 hours). P, Correlation analysis of HIF1α and CXCL12 expression in 50 CAF samples using transcriptome data. Q, Dual-luciferase assays evaluated CXCL12 promoter activity ( n = 3). R and S, T-cell migration and infiltration were analyzed with or without SPP1 protein or MSAB treatment, n = 3. Scale bar, 50 μm. Western blotting ( A–J and L ) and ELISA ( M–O ) were repeated three times, with data representative of three independent experiments. Results are presented as mean ± SEM. P values were determined by one-way ANOVA ( M –O , R , and S ) and two-tailed unpaired Student t test ( F , G , and Q ). *, P < 0.05; **, P < 0.01; ***, P < 0.001. R and S , Created with Figdraw.com .
Article Snippet: Human recombinant SPP1 (HY- P70499 ) and CXCL12 (HY- P70469 ) proteins were obtained from MedChemExpress.
Techniques: Western Blot, Knockdown, Transfection, Immunofluorescence, Fractionation, Expressing, Luciferase, Activity Assay, Migration, Enzyme-linked Immunosorbent Assay, Two Tailed Test