title: Aberrant Hypomethylation of Solute Carrier Family 6 Member 12 Promoter Induces Metastasis of Ovarian Cancer.
abstract: OBJECTIVE
  Ovarian cancer (OC) is the most fatal of gynecological malignancies with a high rate of recurrence. We aimed to evaluate the expression of solute carrier family 6, member 12 (SLC6A12) and methylation of its promoter CpG sites in a xenograft mouse model of metastatic OC, and to investigate the regulatory mechanisms that promote aggressive properties during OC progression.
  
  
  METHODS
  Expression of SLC6A12 mRNA was determined by reverse-transcription quantitative polymerase chain reaction (RT-qPCR), and DNA methylation status of its promoter CpGs was detected by quantitative methylation-specific PCR. The metastatic potential of SLC6A12 was evaluated by in vitro migration/invasion transwell assays. Gene expression and DNA methylation of SLC6A12 and clinical outcomes were further investigated from publicly available databases from curatedOvarianData and The Cancer Genome Atlas.
  
  
  RESULTS
  SLC6A12 expression was 8.1-14.0-fold upregulated and its DNA methylation of promoter CpG sites was 41-62% decreased in tumor metastases. After treatment with DNA methyltransferase inhibitor and/or histone deacetylase inhibitor, the expression of SLC6A12 was profoundly enhanced (~8.0-fold), strongly supporting DNA methylation-dependent epigenetic regulation of SLC6A12. Overexpression of SLC6A12 led to increased migration and invasion of ovarian carcinoma cells in vitro, approximately 2.0-fold and 3.3-fold, respectively. The meta-analysis showed that high expression of SLC6A12 was significantly associated with poor overall survival [hazard ratio (HR)=1.07, p value=0.016] and that low DNA methylation levels of SLC6A12 at specific promoter CpG site negatively affected patient survival.
  
  
  CONCLUSIONS
  Our findings provide novel evidence for the biological and clinical significance of SLC6A12 as a metastasis-promoting gene.
authors.affiliation: Department of Biochemistry, School of Medicine, Ewha Womans University, Seoul, Korea.
authors.forename: Hye Youn
authors.initials: HY
authors.lastname: Sung
authors.affiliation: Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: San Duk
authors.initials: SD
authors.lastname: Yang
authors.affiliation: College of Pharmacy and Research Institute of Life and Pharmaceutical Sciences, Sunchon National University, Suncheon, Korea.
authors.forename: Ae Kyung
authors.initials: AK
authors.lastname: Park
authors.affiliation: Department of Obstetrics and Gynecology, School of Medicine, Ewha Womans University, Seoul, Korea. goodmorning@ewha.ac.kr.
authors.forename: Woong
authors.initials: W
authors.lastname: Ju
authors.affiliation: Department of Biochemistry, School of Medicine, Ewha Womans University, Seoul, Korea. ahnj@ewha.ac.kr.
authors.forename: Jung Hyuck
authors.initials: JH
authors.lastname: Ahn
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D054443:Cell Migration Assays; D018899:CpG Islands; D019175:DNA Methylation; D018450:Disease Progression; D044127:Epigenesis, Genetic; D005260:Female; D050485:GABA Plasma Membrane Transport Proteins; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051379:Mice; D009361:Neoplasm Invasiveness; D009368:Neoplasm Transplantation; D010051:Ovarian Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D016133:Polymerase Chain Reaction; D011379:Prognosis; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D002352:Carrier Proteins; D050485:GABA Plasma Membrane Transport Proteins; D012333:RNA, Messenger; C072207:betaine plasma membrane transport proteins
keywords: DNA methylation; Ovarian cancer; SLC6A12; metastasis; mouse xenograft