Signal crosstalk of VEGF-IL-6-STAT3 between cutaneous melanoma cells and vascular endothe-lial cells / 中华皮肤科杂志

ABSTRACT

Objective:To investigate mechanisms underlying the signal crosstalk of VEGF-IL-6-STAT3 between cutaneous melanoma cells and vascular endothelial cells.Methods:EC-304 vascular endothelial cells were divided into 3 groups control group cultured in conventional endothelial cell-conditioned medium, vascular endothelial growth factor (VEGF) group cultured in endothelial cell-conditioned medium containing 50 μg/L VEGF 165, A375 co-culture group co-cultured with a melanoma cell line A375. After 24-, 48- and 72-hour treatment, the culture medium was collected, and enzyme-linked immunosorbent assay was performed to detect the level of interleukin-6 (IL-6) . Cultured A375 cells were divided into 4 groups control group receiving conventional culture in Dulbecco′s modified Eagle′s medium (DMEM) , A375+ EC-304 group co-cultured with EC-304 cells, A375+ EC-304+ IL-6 group co-cultured with EC-304 cells in DMEM containing 50 μg/L IL-6 (an agonist of the signal transducer and activator of transcription-3 [STAT3] pathway) , A375+ EC-304+ JSI-124 group co-cultured with EC-304 cells in DMEM containing 1 μmol/L JSI-124 (a STAT3 pathway inhibitor) . After 24-, 48- and 72-hour treatment, cells were collected, and Western blot analysis, cell counting kit-8 (CCK8) assay and Transwell invasion assay were performed to determine the protein expression of STAT3 and phosphorylated (p) -STAT3, cellular proliferative activity and invasive activity, respectively. Two-way analysis of variance and t test were used for statistical analysis. Results:The level of IL-6 significantly increased in the culture medium of EC-304 cells in the VEGF group and A375 co-culture group compared with the control group ( FVEGF = 29.63, P < 0.001; FA375 = 11.09, P = 0.020) . Compared with the control group, the A375+ EC-304 group showed significantly enhanced protein expression of p-STAT3 in A375 cells ( P < 0.001) , increased cell activity ( P < 0.001) , and increased number of invasive cells (152.66 ± 16.04 vs. 86.13 ± 7.24, t= 4.43, P < 0.001) ; compared with the A375+ EC-304 group, the A375+ EC-304+ IL-6 group showed significantly increased protein expression of p-STAT3 ( P < 0.001) , enhanced cell activity ( P < 0.001) , and increased number of invasive cells (187.34 ± 14.38, t= 2.17, P < 0.001) ; compared with the A375+ EC-304 group, the A375+ EC-304+ JSI-124 group showed significantly decreased protein expression of p-STAT3 ( P < 0.001) , decreased cell activity ( P < 0.001) , and decreased number of invasive cells (124.92 ± 8.72, t=-1.86, P < 0.001) . Conclusion:There is a signal crosstalk of VEGF-IL-6-STAT3 between cutaneous melanoma cells and vascular endothelial cells, which may play an important role in the proliferation and invasion of A375 cells.