Fig 2: CX3CL1 triggers the phosphorylation of PLCß/PKCa/c-Src to signal the cell movement, migration and ICAM-1 expression in human oral squamous cell carcinoma (OSCC) cells. (A-C) Quantified result of cell movement, cell migration and ICAM-1 expression with signalling inhibitors and CX3CL1 recombinant protein (30 ng/mL) treatment. (D-E) Protein expression of phosphorylated PLCß, PKCa and c-Src with CX3CL1 recombinant protein (30 ng/mL) treatment in SCC4 cell and SAS cell. (F-H) Quantified result of cell movement, cell migration and ICAM-1 expression with PLCß, PKCa or c-Src siRNA and CX3CL1 recombinant protein (30 ng/mL) treatment. Results are expressed as the mean ± SD of four independent experiments. *, p < 0.05 and #, p < 0.05 as compared to control and CX3CL1 treatment.

Fig 3: Model of the changes in expression of CD40, TRAF2, TRAF6, and inflammatory molecules in diabetic retinopathy in humans. Expression of CD40 and its downstream signaling molecules TRAF2 and TRAF6 are increased in retinal Müller cells and endothelial cells from patients with diabetic retinopathy. This is accompanied by increased expression of ICAM-1 in retinal endothelial cells, upregulation of CCL2 in Müller cells, and expression of activated PLCγ1 in Müller cells. TNF-α does not appear to be expressed in Müller or endothelial cells whereas it is detected in cells that likely represent microglia/macrophages. Prior in vitro studies revealed that CD40-TRAF signaling upregulates ICAM-1 in retinal endothelial cells and CCL2 production by Müller cells (Ref. 27), as well as activates PLCγ1 in Müller cells, triggering release of extracellular ATP that in turn promotes TNF-α production by myeloid cells (Ref. 28). Created with BioRender.

Fig 4: CX3CL1 activates tumour cell migration via the ICAM‐1 expression in human oral squamous cell carcinoma (OSCC) cells. (A) ICAM‐1 expression in the normal and tumour cells obtained from the TCGA dataset analysis. (B) VCAM‐1 expression in the normal and tumour cells obtained from the TCGA dataset analysis. (C) Correlation analysis of CX3CL1 and ICAM‐1 expression using the TIMER2.0 database. (D) Correlation analysis of CX3CL1 and VCAM‐1 expression using the TIMER2.0 database. (E) Quantified result of ICAM‐1 gene expression with CX3CL1 recombinant protein (30 ng/mL) treatment. (F) Quantified result of VCAM‐1 gene expression with CX3CL1 recombinant protein (30 ng/mL) treatment. (G) Protein expression of ICAM‐1 with concentration‐depended CX3CL1 treatment. (H) Protein expression of VCAM‐1 with concentration‐depended CX3CL1 treatment. (I) Quantified result of cell migration with ICAM‐1 siRNA and CX3CL1 recombinant protein (30 ng/mL) treatment. (J) Quantified result of cell migration with ICAM‐1 neutralizing antibody and CX3CL1 recombinant protein (30 ng/mL) treatment. Results are expressed as the mean ± SD of four independent experiments. *, p < 0.05 and #, p < 0.05 as compared to control and CX3CL1 treatment.

Fig 5: CX3CL1 upregulates cell motility and ICAM‐1 expression via its receptor CX3CR1. (A) Levels of CX3CR1 mRNA expression in normal tongue tissue and human oral squamous cell carcinoma (OSCC) tumour tissue were analysed using records from the GEO data set GSE13601. (B) Levels of CX3CR1 mRNA expression in different N stages of OSCC tumour tissue were analysed using records from the GEO data set GSE78060. (C) Quantified result of cell movement with CX3CR1 neutralizing antibody and CX3CL1 recombinant protein (30 ng/mL) treatment. (D) Quantified result of cell migration with CX3CR1 neutralizing antibody and CX3CL1 recombinant protein (30 ng/mL) treatment. (E) Quantified resulting of ICAM‐1 expression with CX3CR1 neutralizing antibody and CX3CL1 recombinant protein (30 ng/mL) treatment. (F) Quantified result of cell movement with CX3CR1 siRNA and CX3CL1 recombinant protein (30 ng/mL) treatment. (G) Quantified result of cell migration with CX3CR1 siRNA and CX3CL1 recombinant protein (30 ng/mL) treatment. (H) Quantified result of ICAM‐1 expression with CX3CR1 siRNA and CX3CL1 recombinant protein (30 ng/mL) treatment. Results are expressed as the mean ± SD of four independent experiments. *, p < 0.05 and #, p < 0.05 as compared to control and CX3CL1 treatment.