title: Characterization of P1 promoter activity of the beta-galactoside alpha2,6-sialyltransferase I gene  (siat 1) in cervical and hepatic cancer cell lines.
abstract: The level of beta-galactoside alpha2,6-sialyltransferase I (ST6Gal I) mRNA, encoded by the gene siat1,  is increased in malignant tissues. Expression is regulated by different promoters - P1, P2 and P3 - generating three mRNA isoforms H, X and YZ. In cervical cancer tissue the mRNA isoform H, which results from P1 promoter activity, is increased. To study the regulation of P1 promoter, different constructs from P1 promoter were evaluated by luciferase assays in cervical and hepatic cell lines. Deletion of a fragment of 1048 bp (-89 to +24 bp) increased 5- and 3-fold the promoter activity in C33A and HepG2 cell lines, respectively. The minimal region with promoter activity was a 37 bp fragment in C33A cells. The activity of this region does not require the presence of an initiator sequence. In HepG2 cells the minimal promoter activity was detected in the 66 bp fragment. Sp1 (-32) mutation increased the promoter activity only in HepG2 cells. HNF1 mutation decreased promoter activity in HepG2 cell line but not in C33A cells. We identified a large region that plays a negative regulation role. The regulation of promoter activity is cell type specific. Our study provides new insights into the complex transcriptional regulation of siat1 gene.
authors.affiliation: Laboratorio de Biologia Molecular y Virologia, Centro de Investigacion Biomedica de Oriente, Instituto Mexicano del Seguro Social, Hospital General de Zona No. 5, Km 4.5 Carretera Federal Atlixco-Metepec,  74360 Metepec, Puebla, Mexico.
authors.forename: Lorena
authors.initials: L
authors.lastname: Milflores-Flores
authors.forename: Lourdes
authors.initials: L
authors.lastname: Millán-Pérez
authors.forename: Gerardo
authors.initials: G
authors.lastname: Santos-López
authors.forename: Julio
authors.initials: J
authors.lastname: Reyes-Leyva
authors.forename: Verónica
authors.initials: V
authors.lastname: Vallejo-Ruiz
mesh_terms: D015703:Antigens, CD / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D005260:Female; D015870:Gene Expression; D056945:Hep G2 Cells; D051537:Hepatocyte Nuclear Factor 1 / Q000235:genetics; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D059368:RNA Isoforms / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012799:Sialyltransferases / Q000235:genetics* / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000276:immunology; D002583:Uterine Cervical Neoplasms / Q000201:enzymology / Q000235:genetics*; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
chemical_list: D015703:Antigens, CD; D051537:Hepatocyte Nuclear Factor 1; D059368:RNA Isoforms; D012333:RNA, Messenger; D012799:Sialyltransferases; D016329:Sp1 Transcription Factor; C093493:ST6GAL1 protein, human; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase