Fig. 4: Knockdown of DDR1 in MSS CRC cell lines could increase CXCL10 secretion.

a Volcano and Venn plots showing significantly elevated CXCL10 RNA expression by chemokine profile analysis in the shDdr1 mouse MSS CRC cell line CT26 and the human MSS CRC cell lines HT29 and SW620 after stimulation with collagen I and IFNγ (20 ng/ml) compared to control RNA-transfected cells. |Log2fold change | >1.2, | p adj | >0.05). b, c GO and KEGG enrichment analysis of the DEGs (DEGs, differentially expressed genes; GO,gene ontology). Dot plot and bar plot showed DEGs enriched in histone modification in the BP (biological process) category, chromosome region in the CC (cellular component) category and proteoglycans in cancer in shDDR1 CRC cell lines compared to shNC cell lines after collagen I and IFNγ (20 ng/ml) by KEGG and GO analysis. d Chord diagram showing the top 100 ranked upregulated genes by GO analysis in SW620-shDDR1 cells compared to SW620-shNC cells stimulated with collagen I and IFNγ (20 ng/ml). e Western blotting of DDR1 knockdown CRC cell lines showed decreased levels of DDR1 and phosphorylated DDR1 kinase ___domain (Tyr792) but increased supernatant CXCL10 levels in shDDR1 cell lines stimulated with collagen I and a small dose of IFNγ (20 ng/ml (WB protein levels were normalized to β-actin level). f ELISA verified elevated supernatant CXCL10 levels and increased RNA expression of CXCL10 in the shDDR1 human MSS CRC cell lines HT29 and SW620 compared to the control group stimulated with collagen I and a small dose of IFNγ (20 ng/ml) (ELISA was quantified with the same volume of supernatant of 1 × 10⁷ cells). g, h CXCL10 RNA levels were quantified by RT-PCR and normalized to GAPDH levels (detected by real-time PCR, fold change shown relative to GAPDH). Three independent experiments are shown with stimulation by IFNγ (20 ng/ml) and stimulation by both collagen I and IFNγ (20 mg/ml).