L-carnosine reduces the HIF-1α protein level affecting its stability and induces HIF-1α proteasome-dependent degradation.

<p>(A) Western blotting analysis probed with anti-HIF-1α antibody of immunoprecipitated proteins in HCT-116; (B) western blotting analysis of total protein extracts from HCT-116 cells 24 h after L-carnosine (100 mM) or L-carnosine (100 mM) plus 10 mM cycloheximide (CHX) treatment probed with HIF-1α and β-actin antibodies. Related histograms report the densitometric values of HIF-1α/β-actin ratio; (C) western blotting analysis of total protein extracts from HCT-116 cells 24 h after L-carnosine (100 mM) or L-carnosine (100 mM) plus 1 mM MG132 treatment probed with HIF-1α and β-actin antibodies. The densitometric values represent the mean ± SDs of three independent experiments. The differences were considered significant at **p<0.001, ***p<0.0001; (D) Schematic representation of ODD-LUC reporter vector. ODD-LUC vector contains the oxygen-dependent degradation (ODD) domain of HIF-1α cloned upstream from the luciferase gene. The luciferase activity was measured 48 h after transfection and represents the mean ± SDs of three independent experiments. The values have been reported as percentages of luciferase activity compared to 100% of untreated cells.