title: Integrated, genome-wide screening for hypomethylated oncogenes in salivary gland adenoid cystic carcinoma.
abstract: OBJECTIVE
  Salivary gland adenoid cystic carcinoma (ACC) is a rare malignancy that is poorly understood. To look for relevant oncogene candidates under the control of promoter methylation, an integrated, genome-wide screen was conducted.
  
  
  METHODS
  Global demethylation of normal salivary gland cell strains using 5-aza-2'-deoxycytidine (5-aza-dC) and trichostatin A (TSA), followed by expression array analysis was conducted. ACC-specific expression profiling was generated using expression microarray analysis of primary ACC and normal samples. Next, the two profiles were integrated to identify a subset of genes for further validation of promoter demethylation in ACC versus normal. Finally, promising candidates were further validated for mRNA, protein, and promoter methylation levels in larger ACC cohorts. Functional validation was then conducted in cancer cell lines.
  
  
  RESULTS
  We found 159 genes that were significantly re-expressed after 5-aza-dC/TSA treatment and overexpressed in ACC. After initial validation, eight candidates showed hypomethylation in ACC: AQP1, CECR1, C1QR1, CTAG2, P53AIP1, TDRD12, BEX1, and DYNLT3. Aquaporin 1 (AQP1) showed the most significant hypomethylation and was further validated. AQP1 hypomethylation in ACC was confirmed with two independent cohorts. Of note, there was significant overexpression of AQP1 in both mRNA and protein in the paraffin-embedded ACC cohort. Furthermore, AQP1 was upregulated in 5-aza-dC/TSA-treated SACC83. Finally, AQP1 promoted cell proliferation and colony formation in SACC83.
  
  
  CONCLUSIONS
  Our integrated, genome-wide screening method proved to be an effective strategy for detecting novel oncogenes in ACC. AQP1 is a promising oncogene candidate for ACC and is transcriptionally regulated by promoter hypomethylation.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery and Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors.forename: Chunbo
authors.initials: C
authors.lastname: Shao
authors.forename: Wenyue
authors.initials: W
authors.lastname: Sun
authors.forename: Marietta
authors.initials: M
authors.lastname: Tan
authors.forename: Chad A
authors.initials: CA
authors.lastname: Glazer
authors.forename: Sheetal
authors.initials: S
authors.lastname: Bhan
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhong
authors.forename: Carole
authors.initials: C
authors.lastname: Fakhry
authors.forename: Rajni
authors.initials: R
authors.lastname: Sharma
authors.forename: William H
authors.initials: WH
authors.lastname: Westra
authors.forename: Mohammad O
authors.initials: MO
authors.lastname: Hoque
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Moskaluk
authors.forename: David
authors.initials: D
authors.lastname: Sidransky
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Califano
authors.forename: Patrick K
authors.initials: PK
authors.lastname: Ha
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D051398:Aquaporin 1 / Q000235:genetics / Q000378:metabolism; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D003528:Carcinoma, Adenoid Cystic / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003570:Cytidine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D019175:DNA Methylation / Q000235:genetics*; D057890:Epigenomics; D005260:Female; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005820:Genetic Testing; D055106:Genome-Wide Association Study; D006801:Humans; D008297:Male; D008875:Middle Aged; D009857:Oncogenes / Q000235:genetics*; D012468:Salivary Gland Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D015854:Up-Regulation / Q000187:drug effects
chemical_list: C496020:AQP1 protein, human; D000964:Antimetabolites, Antineoplastic; D051398:Aquaporin 1; D003570:Cytidine Triphosphate; C038673:5-aza-2'-deoxycytidine-5'-triphosphate; D001374:Azacitidine