Fig. 4

Upregulation of MHC class I APM and IFN signaling components and altered NK cell response by restoration of PRELP in PRELP^low/neg B16F10 and Buf1088 cells. A PRELP-mediated upregulation of MHC class I surface antigen expression. MHC class I surface expression was assessed by flow cytometry in PRELP^low/neg vs. PRELP^high B16F10 and Buf1088 cells as described in “Methods”. The data are represented as histograms of MHC class I surface expression of PRELP^low/neg vs. PRELP^high B16F10 and Buf1088 cells. B PRELP-mediated upregulation of MHC class I APM components expression in melanoma cells. The mRNA expression levels of MHC class I APM components in PRELP^low/neg vs. PRELP^high melanoma cells were analyzed by qPCR as described in “Methods”. The results are expressed in bar charts representing the mean of three independent experiments as relative mRNA expression levels of selected APM components in PRELP^low/neg and PRELP^high B16F10 and Buf1088 cells. C. Transcriptional downregulation of selected MHC class I APM components in PRELP^low/neg melanoma cells. APM promoter activity in PRELP^low/high, mock transfectants and two independent PRELP transfectants of B16F10 cells was determined by luciferase assays as described in “Methods”. The data were normalized to β-gal activity and presented in a bar chart as the mean of the relative luc activity of at least three independent experiments. Error bars indicate the standard error. The statistical significance is presented as *p < 0.05; **p < 0.01