Sp1 plays an important role in nicotine-mediated LDLR expression.

(A) Ca9-22 cells were pre-treated with or without mithramycin for 1 h. After washes, the cells were stimulated with 100 μM of nicotine for 3 h and luciferase activity was measured. (B) Ca9-22 cells were transfected with various concentrations of siRNA against Sp1 or control siRNA (con) for 3 h. After transfection, the cells were stimulated with or without 100 μM of nicotine for 3 h. The expression level of LDLR mRNA was examined by real-time PCR. (C) The silencing effect of siRNA transfection on the expression of Sp1 was assessed by real-time PCR. Sp1 expression level of control siRNA-transfected Ca9-22 cell was set as 1. The data are presented as mean ± SD of at least 3 separate experiments. *p < 0.05.