Regulation of the angiopoietin-2 gene by hCG in ovarian cancer cell line OVCAR-3.
Angiogenesis is a crucial step in growing tissues including many tumors. It is regulated by pro- and antiangiogenic factors including the family of angiopoietins and their corresponding receptors. In previous work we have shown that in human ovarian cells the expression of angiopoietin 2 (ANG2) is regulated by human chorionic gonadotropin (hCG). To better understand the mechanisms of hCG-dependent regulation of the ANG2-gene we have now investigated upstream regulatory active elements of the ANG2-promoter in the ovarian carcinoma cell line OVCAR-3. We cloned several ANG2-promoter-fragments of different lengths into a luciferase reporter-gene-vector and analyzed the corresponding ANG2 expression before and after hCG stimulation. We identified regions of the ANG2-promoter between 1 048 bp and 613 bp upstream of the transcriptional start site where hCG-dependent pathways promote a significant downregulation of gene expression. By sequence analysis of this area we found several potential binding sites for transcription factors that are involved in regulation of ANG2-expression, vascular development and ovarian function. These encompass the forkhead family transcription factors FOXC2 and FOXO1 as well as the CCAAT/enhancer binding protein family (C/EBP). In conclusion, we have demonstrated that the regulation of ANG2-expression in ovarian cancer cells is hCG-dependent and we suggest that forkhead transcription factor and C/EBP-dependent pathways are involved in the regulation of ANG2-expression in ovarian cancer cells.
Pietrowski
D
D
Department for Obstetrics and Gynecology, Medical University Vienna, Vienna, Austria. detlef.pietrowski@meduniwien.ac.at
Wiehle
P
P
Sator
M
M
Just
A
A
Keck
C
C
D042702:Angiopoietin-2 / Q000235:genetics*; D045744:Cell Line, Tumor; D006063:Chorionic Gonadotropin / Q000502:physiology*; D003001:Cloning, Molecular; D017931:DNA Primers; D005260:Female; D051858:Forkhead Transcription Factors / Q000235:genetics; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D007986:Luteinizing Hormone / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011974:Receptors, LH / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
D042702:Angiopoietin-2; D006063:Chorionic Gonadotropin; D017931:DNA Primers; D051858:Forkhead Transcription Factors; D011974:Receptors, LH; D007986:Luteinizing Hormone