Figure 4From: Matrix metalloproteinase 12 is induced by heterogeneous nuclear ribonucleoprotein K and promotes migration and invasion in nasopharyngeal carcinoma Transcriptional regulation of MMP12 by hnRNP K. (A) Schematic diagrams of the utilized reporter constructs, which contained 5' serial deletions of the MMP12 promoter. (B) NPC-TW02 cells were pretreated with control siRNA (C) or hnRNP K-targeting siRNA (K) for 24 h and then transfected with pGL3-basic (pGL3) with or without 5' serial deletions of the promoter sequence of the MMP 12. Firefly and Renilla luciferase activities were determined at 24 h post-transfection. *P < 0.05. (C) DNA pull-down assays were performed using nuclear extracts isolated from NPC-TW02 cells and 5' biotin-labeled probes corresponding to the −42/+97 (−42 to +97) or +2/+97 (+2 to +97) regions of the MMP12 promoter. The hnRNP K levels in the immunoprecipitates and 1% inputs were determined by Western blotting. (D) Chromatin immunoprecipitation was carried out using nuclear extracts from NPC-TW02 cells and an antibody against hnRNP K, followed by quantitative PCR of a sequence within the MMP12 promoter region (−95 to −20). Mouse IgG immunoprecipitation was done as a negative control. *P < 0.01.Back to article page