title: RAB25 expression is epigenetically downregulated in oral and oropharyngeal squamous cell carcinoma with lymph node metastasis.
abstract: Oral and oropharyngeal squamous cell carcinoma (OOSCC) have a low survival rate, mainly due to metastasis to the regional lymph nodes. For optimal treatment of these metastases, a neck dissection is required; however, inaccurate detection methods results in under- and over-treatment. New DNA prognostic methylation biomarkers might improve lymph node metastases detection. To identify epigenetically regulated genes associated with lymph node metastases, genome-wide methylation analysis was performed on 6 OOSCC with (pN+) and 6 OOSCC without (pN0) lymph node metastases and combined with a gene expression signature predictive for pN+ status in OOSCC. Selected genes were validated using an independent OOSCC cohort by immunohistochemistry and pyrosequencing, and on data retrieved from The Cancer Genome Atlas. A two-step statistical selection of differentially methylated sequences revealed 14 genes with increased methylation status and mRNA downregulation in pN+ OOSCC. RAB25, a known tumor suppressor gene, was the highest-ranking gene in the discovery set. In the validation sets, both RAB25 mRNA (P = 0.015) and protein levels (P = 0.012) were lower in pN+ OOSCC. RAB25 mRNA levels were negatively correlated with RAB25 methylation levels (P < 0.001) but RAB25 protein expression was not. Our data revealed that promoter methylation is a mechanism resulting in downregulation of RAB25 expression in pN+ OOSCC and decreased expression is associated with lymph node metastasis. Detection of RAB25 methylation might contribute to lymph node metastasis diagnosis and serve as a potential new therapeutic target in OOSCC.
authors.affiliation: a Departments of Pathology , University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.|b Oral and Maxillofacial Surgery, University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.
authors.forename: M J A M
authors.initials: MJ
authors.lastname: Clausen
authors.affiliation: a Departments of Pathology , University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.|b Oral and Maxillofacial Surgery, University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.
authors.forename: L J
authors.initials: LJ
authors.lastname: Melchers
authors.affiliation: a Departments of Pathology , University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.
authors.forename: M F
authors.initials: MF
authors.lastname: Mastik
authors.affiliation: a Departments of Pathology , University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.|c Otorhinolaryngology/Head & Neck Surgery, University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: Slagter-Menkema
authors.affiliation: d Pulmonary Diseases, University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.
authors.forename: H J M
authors.initials: HJ
authors.lastname: Groen
authors.affiliation: c Otorhinolaryngology/Head & Neck Surgery, University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.
authors.forename: B F A M van der
authors.initials: BF
authors.lastname: Laan
authors.affiliation: e Department of Mathematical Modeling , Statistics and Bioinformatics, Ghent University , Ghent , Belgium.
authors.forename: W
authors.initials: W
authors.lastname: van Criekinge
authors.affiliation: e Department of Mathematical Modeling , Statistics and Bioinformatics, Ghent University , Ghent , Belgium.
authors.forename: T
authors.initials: T
authors.lastname: de Meyer
authors.affiliation: f Gynecologic Oncology, University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Denil
authors.affiliation: a Departments of Pathology , University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: van der Vegt
authors.affiliation: f Gynecologic Oncology, University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.
authors.forename: G B A
authors.initials: GB
authors.lastname: Wisman
authors.affiliation: b Oral and Maxillofacial Surgery, University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.
authors.forename: J L N
authors.initials: JL
authors.lastname: Roodenburg
authors.affiliation: a Departments of Pathology , University of Groningen, University Medical Center Groningen , Groningen , the Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Schuuring
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000473:pathology; D019175:DNA Methylation; D015536:Down-Regulation; D044127:Epigenesis, Genetic; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009959:Oropharyngeal Neoplasms / Q000235:genetics* / Q000473:pathology; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; C509763:Rab25 protein, human; D020691:rab GTP-Binding Proteins
keywords: DNA methylation; MethylCap-Seq; epigenetic regulation; head and neck cancer; metastasis; oral squamous cell carcinoma