Characterization of Human Mucin GeneMUC4Promoter

Michaël Perrais, Pascal Pigny, Marie-Paule Ducourouble, Danièle Petitprez, Nicole Porchet, Jean-Pierre Aubert, Isabelle Van Seuningen
2001 Journal of Biological Chemistry  
The human mucin gene MUC4 encodes a large transmembrane mucin that is thought to play important roles in tumor cell biology and that is overexpressed in human pancreatic carcinomas. In this report, we describe the structure and functional activity of the 5-flanking region, including 1.0 kilobase of the promoter. The long 5-untranslated region (2.7 kilobases) is characterized by a high content of GC in its 3-end. The first TATA box was located at ؊2672/؊2668. Multiple transcription start sites
more » ... d a high density of putative binding sites for Sp1 (GC and CACCC boxes), AP-1/-2/-4, cAMP-responsive element-binding protein, GATA, GR, and STAT transcription factors were found within the 5-flanking region. Transcriptional activity of the promoter was assessed using pGL3-luciferase deletion mutants in two MUC4-expressing (CAPAN-1 and CAPAN-2) and one nonexpressing (PANC-1) pancreatic cancer cell line. Two highly active fragments (؊219/؊1 and ؊2781/؊2572) that drive MUC4 transcription in CAPAN-1 and CAPA-N-2 cells were identified. Gel retardation assays indicated that Sp1 and Sp3 bind to cognate cis-elements found in the 5-flanking region and that Sp1 transactivates, whereas Sp3 inhibits the GC-rich region (؊464/؊1) in CAPAN-2 cells. Activation of protein kinase C with phorbol ester and treatment of cells with epidermal growth factor and transforming growth factor-␣ resulted in upregulation of the promoter. Tumor necrosis factor-␣ and interferon (IFN)-␥ inflammatory cytokines had no or mild effect on MUC4 transcriptional activity when used alone. However, a very strong synergistic effect (10 -12fold activation) between IFN-␥ and tumor necrosis factor-␣ or IFN-␥ and transforming growth factor-␣ was obtained in CAPAN-2 cells. Altogether these results demonstrate that the 5-flanking region of MUC4 contains epithelial cell-specific, positive, and negative regulatory cis-elements, that Sp1/Sp3 are important regulators of MUC4 basal expression, and that its regulation in pancreatic cancer cells involves complex interplay between several signaling pathways.
doi:10.1074/jbc.m104204200 pmid:11418607 fatcat:zmpvbul46ndprgi2r5tvam3fxe