Fig. 4

IFN-γ upregulated HLA-E expression through activation of STAT1 signal transduction pathway. (A) Caerulomycin A suppressed IFN-γ-induced STAT1 phosphorylation. HLA-E protein expression was also decreased with the increase of Caerulomycin A concentration. (B) Cell surface HLA-E expression was not downregulated by Caerulomycin A treatment. (C) SKOV3 cells transfected with EGFP were observed after being cultured with NKL cells for 4 h. More tumor cells were survived in IFN-γ stimulating group than in control group (without treatment). Caerulomycin A did not abrogate the IFN-γ-induced survivals. The bars = 250 μm. (D) IFN-γ reduced the function of NK lysis, and Caerulomycin A had no effect on IFN-γ-mediated killing inhibition, which was shown through LDH cytotoxicity assay kit. ^**P < 0.01, ^***P < 0.001. Data shown represented one of three independent experiments