Yonsei Med J.  2014 Nov;55(6):1656-1663. 10.3349/ymj.2014.55.6.1656.

DNA Hypomethylation-Mediated Overexpression of Carbonic Anhydrase 9 Induces an Aggressive Phenotype in Ovarian Cancer Cells

• Sung HY
• Ju W
• Ahn JH

• KMID: 2070216
• DOI: http://doi.org/10.3349/ymj.2014.55.6.1656

Abstract

PURPOSE
Both genetic and epigenetic alterations can lead to abnormal expression of metastasis-regulating genes in tumor cells. Recent studies suggest that aberrant epigenetic alterations, followed by differential gene expression, leads to an aggressive cancer cell phenotype. We examined epigenetically regulated genes that are involved in ovarian cancer metastasis.
MATERIALS AND METHODS
We developed SK-OV-3 human ovarian carcinoma cell xenografts in mice. We compared the mRNA expression and DNA methylation profiles of metastatic tissues to those of the original SK-OV-3 cell line.
RESULTS
Metastatic implants showed increased mRNA expression of the carbonic anhydrase 9 (CA9) gene and hypomethylation at CpG sites in the CA9 promoter. Treatment of wild-type SK-OV-3 cells with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine reduced methylation of the CA9 promoter and increased CA9 mRNA expression. Eight CpGs, which were located at positions -197, -74, -19, -6, +4, +13, +40, and +86, relative to the transcription start site, were hypomethylated in metastatic tumor implants, compared to that of wild-type SK-OV-3. Overexpression of CA9 induced an aggressive phenotype, including increased invasiveness and migration, in SK-OV-3 cells.
CONCLUSION
Alterations in the DNA methylation profile of the CA9 promoter were correlated with a more aggressive phenotype in ovarian cancer cells.

Keyword

Ovarian cancer; metastasis; mouse xenograft; CA9; DNA methylation

MeSH Terms

Animals
Azacitidine/*analogs & derivatives/pharmacology
Carbonic Anhydrases/metabolism
*DNA Methylation
Female
Gene Expression Regulation, Neoplastic/*drug effects
Humans
Mice
Neoplasm Invasiveness/genetics
Neoplasm Metastasis/genetics/*pathology
Neoplasms, Experimental
Neoplasms, Glandular and Epithelial/genetics/*metabolism/pathology
Ovarian Neoplasms/genetics/*metabolism/pathology
Phenotype
Promoter Regions, Genetic
RNA, Messenger/metabolism
Azacitidine
Carbonic Anhydrases
RNA, Messenger