title: Detection of O6-methylguanine-DNA methyltransferase gene promoter region methylation pattern using pyrosequencing and the effect of methylation pattern on survival, recurrence, and chemotherapy sensitivity in patients with laryngeal cancer.
abstract: OBJECTIVE
  To determine the methylation pattern of the promoter region of the O6-methylguanine-DNA methyltransferase (MGMT) gene in laryngeal cancer and normal laryngeal mucosa samples using pyrosequencing, and to determine the relationship between the methylation pattern of MGMT, and tumor stage, survival, recurrence, and chemosensitivity in patients with laryngeal cancer.
  
  
  METHODS
  Laryngeal cancer and normal laryngeal mucosa specimens were obtained from our paraffin block archives, and then subjected to pyrosequencing. Different cut-off values were used to detect methylation. Clinicopathological data for the patients that provided specimens were obtained from archive records.
  
  
  RESULTS
  When 5% was used as the cut-off value, 78% of the laryngeal cancer specimens (64 of 82), and 27.3% of normal laryngeal mucosa specimens (3 of 11) were considered methylated. When 10% was used as the cut-off value, 47% of the laryngeal cancer specimens (39 of 82), and none of the normal laryngeal mucosa specimens were considered methylated. There was not a significant relationship between the methylation status of MGMT, and clinicopathological parameters, including age, tumor stage, histopathological differentiation, chemoradiotherapy protocol used, recurrence, or disease-free survival.
  
  
  CONCLUSIONS
  Pyrosequencing is a reliable semiquantitative technique that can be used to detect the methylation pattern. Methylation was common in the laryngeal cancer specimens, but there was not a significant relationship between the methylation status of MGMT and clinicopathological parameters.
authors.affiliation: Department of Otorhinolaryngology, Hacettepe University, Sihhiye 06100, Ankara, Turkey. Electronic address: oonerci@yahoo.com.
authors.forename: Ozlem
authors.initials: O
authors.lastname: Onerci Celebi
authors.affiliation: Department of Pathology, Hacettepe University, Sihhiye 06100, Ankara, Turkey.
authors.forename: Gaye Guler
authors.initials: GG
authors.lastname: Tezel
authors.affiliation: Department of Otorhinolaryngology, Hacettepe University, Sihhiye 06100, Ankara, Turkey.
authors.forename: Ali Sefik
authors.initials: AS
authors.lastname: Hosal
authors.affiliation: Department of Radiation Oncology, Hacettepe University, Sihhiye 06100, Ankara, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Cengiz
authors.affiliation: Department of Medical Oncology, Hacettepe University, Sihhiye 06100, Ankara, Turkey.
authors.forename: Ibrahim Halil
authors.initials: IH
authors.lastname: Gullu
authors.affiliation: Department of Preventive Oncology, Hacettepe University Cancer Institute, Sihhiye 06100, Ankara, Turkey.
authors.forename: Mutlu
authors.initials: M
authors.lastname: Hayran
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007820:Laryngeal Mucosa / Q000473:pathology; D007822:Laryngeal Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D009367:Neoplasm Staging; D011379:Prognosis; D011401:Promoter Regions, Genetic; D015996:Survival Rate; D016896:Treatment Outcome; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: D000970:Antineoplastic Agents; D025521:Tumor Suppressor Proteins; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes
keywords: Chemotherapy sensitivity; Laryngeal cancer; O6-methylguanine-DNA methyltransferase methylation; Pyrosequencing; Survival