Comparative analysis of the effects of IFN-γ and TNF-α on the expression of the immunoproteasome subunits and TAPs.

The expression of TAP1, TAP2, LMP2, LMP7, MECL-1, and heavy chain proteins in the 0505 melanoma cell line was assessed by Western blot analysis and then by densitometry analysis on the specific bands. Expression of the protein of interest was analyzed by the same Western blot procedure in 3 different samples: cells propagated in complete medium (designated as untreated), in the medium containing IFN-γ (500 U/mL), or in the medium containing TNF-α (30 ng/mL). Data shown in the figure are expressed as percentage band intensity of each specific protein band in the tumor sample (untreated or treated with either of the cytokines) relative to that of the corresponding protein band in the lymphoblastoid cell line unexposed to any lymphokine (positive control), arbitrarily defined as 100% band intensity. Expression of the protein of interest in tumor cells is calculated as a percentage expression relative to that observed in a positive control and designated as relative expression. Two to 3 independent experiments were performed for each protein. Results of one experiment are shown in the figure.