title: Altered levels of miR-21, miR-125b-2*, miR-138, miR-155, miR-184, and miR-205 in oral squamous cell carcinoma and association with clinicopathological characteristics.
abstract: BACKGROUND
  Previous studies have described the aberrantly expressed microRNAs (miRNAs) in oral squamous cell carcinoma (OSCC), and we reasoned that studying frequently deregulated candidate miRNAs in OSCC of Indian ethnicity could aid in better understanding of the genetic/environmental impact on the expression statuses of these miRNAs. Therefore, we evaluated the differential expression of six selected miRNAs namely hsa-miR-21, hsa-miR-125b2*, hsa-miR-138, hsa-miR-155, hsa-miR-184, and hsa-miR-205 in OSCC specimens of Indian ethnicity.
  
  
  METHODS
  Two-step Reverse transcriptase quantitative PCR using inventoried TaqMan single miRNA assays was employed to study the expression of the selected miRNAs in 42 OSCC tumors and eight adjacent normal specimens. The expression levels of the miRNAs were tested for any association with clinicopathological parameters.
  
  
  RESULTS
  miR-21 was significantly elevated while miR-125b-2* was significantly downregulated in tumors compared to controls (P < 0.01 and P < 0.05 respectively). miR-138 and miR-184 were observed to be predominantly downregulated in the tumor samples. High levels of miR-155 were associated with the habit of chewing tobacco/betel quid.
  
  
  CONCLUSIONS
  Our results corroborate the previous findings on the overexpression of mir-21 and downregulation of miR-138 in OSCC. As the expression of miR-184 is controversial in tongue/oral cancer, the downregulation may be specific to tumor anatomical localization. On the other hand, to the best of our knowledge, this is the first report to show the association of miR-155 with tobacco chewing and the downregulation of miR-125b-2* in OSCC. Computational predictions suggest that miR-125b-2* may have a role in alternative splicing.
authors.affiliation: Department of Genetics, Dr. ALM PG Institute of Basic Medical Sciences, University of Madras, Chennai, India.
authors.forename: Mayakannan
authors.initials: M
authors.lastname: Manikandan
authors.affiliation: Department of Genetics, Dr. ALM PG Institute of Basic Medical Sciences, University of Madras, Chennai, India.
authors.forename: Arunagiri K
authors.initials: AK
authors.lastname: Deva Magendhra Rao
authors.affiliation: Centre for Oncology, Government Royapettah hospital & Kilpauk Medical College, Chennai, India.
authors.forename: Kottayasamy Seenivasagam
authors.initials: KS
authors.lastname: Rajkumar
authors.affiliation: Centre for Oncology, Government Royapettah hospital & Kilpauk Medical College, Chennai, India.
authors.forename: Ramamurthy
authors.initials: R
authors.lastname: Rajaraman
authors.affiliation: Department of Genetics, Dr. ALM PG Institute of Basic Medical Sciences, University of Madras, Chennai, India.
authors.forename: Arasambattu K
authors.initials: AK
authors.lastname: Munirajan
mesh_terms: D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D015536:Down-Regulation; D005260:Female; D020869:Gene Expression Profiling; D006258:Head and Neck Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D000077195:Squamous Cell Carcinoma of Head and Neck
chemical_list: D035683:MicroRNAs
keywords: head and neck cancer; microRNA; oral cancer; quantitative PCR; squamous cell carcinoma