title: Down-regulation of Sox7 is associated with aberrant activation of Wnt/b-catenin signaling in endometrial cancer.
abstract: Although the mortality rate of endometrial cancer is comparatively low in gynecologic malignancies, a rising trend of this cancer has been observed for the past decade. The understanding of the molecular mechanism will favor for the clinical management of this disease. Aberrant activation of Wnt/β-catenin signaling pathway plays a major role in the pathogenesis of endometrioid adenocarcinoma including this cancer type. In this study, we reported that Sox7, one of Sox transcriptional factors, was frequently underexpressed in endometrial cancer and importantly, it was associated with dysregulation of the Wnt/β-catenin signaling activity. Immunohistochemical and quantitative RT-PCR analyses showed that Sox7 was underexpressed and was associated with high-grade tumor (P=0.021), increased expressions of β-catenin (P=0.038) and its downstream targets; CyclinD1 (P less than 0.001) and FGF9 (P less than 0.001). In addition, using HEK293T cell model, we found that Sox7 was able to inhibit TCF/LEF-1-dependent luciferase activity induced by Wnt-1. This was further proved by that Sox7 could significantly suppress the expressions of Wnt targets; Cyclin D1 and C-myc in endometrial cells. Immuno-fluorescent microscopy revealed that Sox7 was co-localizaed with either mutant β-catenin or TCF4 protein in nucleus, while co-immunopreciptation assay demonstrated that Sox7 could physically interact with not only wild-type but also mutant β-catenin, as well as TCF4 proteins. Functionally, enforced expression of Sox7 could significantly inhibit endometrial or endometrioid ovarian cancer cells (OEA) harboring either wild-type or mutant β-catenin. These data suggest Sox7 is a negative regulator of Wnt/β-catenin signaling pathway through impeding the transcriptional machinery of β-catenin/TCF/LEF-1 transcriptional complex, and the loss of expression may be involved in the pathogenesis of endometrial cancer.
authors.affiliation: Departments of Obstetrics and Gynaecology, LKS Faculty of Medicine, the University of Hong Kong, Hong Kong SAR, PRChina.
authors.forename: David W
authors.initials: DW
authors.lastname: Chan
authors.forename: Celia S L
authors.initials: CS
authors.lastname: Mak
authors.forename: Thomas H Y
authors.initials: TH
authors.lastname: Leung
authors.forename: Karen K L
authors.initials: KK
authors.lastname: Chan
authors.forename: Hextan Y S
authors.initials: HY
authors.lastname: Ngan
mesh_terms: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000378:metabolism; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D002470:Cell Survival; D019938:Cyclin D1 / Q000378:metabolism; D015536:Down-Regulation; D016889:Endometrial Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005260:Female; D051525:Fibroblast Growth Factor 9 / Q000378:metabolism; D017930:Genes, Reporter; D057809:HEK293 Cells; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D051821:Lymphoid Enhancer-Binding Factor 1 / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009154:Mutation; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055760:SOXF Transcription Factors / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D000073940:Transcription Factor 4; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D060449:Wnt Signaling Pathway / Q000235:genetics; D051155:Wnt1 Protein / Q000378:metabolism; D060509:Wnt3A Protein / Q000378:metabolism; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C530104:CCND1 protein, human; C495270:CTNNB1 protein, human; C496459:FGF9 protein, human; D051525:Fibroblast Growth Factor 9; D051821:Lymphoid Enhancer-Binding Factor 1; C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc; C484456:SOX7 protein, human; D055760:SOXF Transcription Factors; C532096:TCF4 protein, human; D000073940:Transcription Factor 4; D014157:Transcription Factors; C495247:WNT1 protein, human; C555510:WNT3A protein, human; D051153:Wnt Proteins; D051155:Wnt1 Protein; D060509:Wnt3A Protein; D051176:beta Catenin; D019938:Cyclin D1