Fig. 4

Xanthohumol promotes survivin ubiquitination and degradation in an Fbxl7-dependent manner. a MG132 rescued xanthohumol-induced survivin downregulation. OSCC cells were treated with xanthohumol, followed by MG132 treated for 6 h. The whole-cell extract was subjected to IB analysis. b MG132 rescued xanthohumol-induced survivin downregulation time-dependently. OSCC cells were treated with xanthohumol, followed by MG132 treated for various time points, whole-cell extract was subjected to IB analysis. c Xanthohumol shortened the half-life of survivin. SCC25 cells were treated with xanthohumol or DMSO control, followed by MG132 treated for 6 h or not, whole-cell extract was subjected to IB analysis. d Xanthohumol promoted survivin ubiquitination. SCC25 cells were treated with xanthohumol and subjected to ubiquitination analysis. e SCC25 cells were transfected with HA-Fbxl7 for 48 h. Cell lysates were subjected to IB analysis. f SCC25 cells were transfected with HA-Fbxl7 and Flag-Survivin plasmids as indicated, followed by xanthohumol treated for 24 h, the whole-cell lysate was prepared and subjected to Co-IP and IB analysis. g SCC25 cells were transfected with various plasmids as indicated, followed by xanthohumol treated for 24 h, the whole-cell lysate was subjected to ubiquitination analysis. h SCC25 cells were transfected with various siRNA as indicated, followed by xanthohumol treated for 24 h, the whole-cell lysate was prepared and subjected to Co-IP and IB analysis. i SCC25 cells were transfected with Flag-Survivin-WT or K90/91R mutant together with HA-Fbxl7 as indicated, followed by xanthohumol treated for 24 h, the whole-cell lysate was prepared and subjected to ubiquitination analysis. j SCC25 cells were transfected with Flag-Survivin-WT or K90/91R mutant and treated with xanthohumol for 24 h. The whole-cell lysate was prepared and subjected to ubiquitination analysis