title: Akt2 and p-Akt overexpression in oral cancer cells is due to a reduced rate of protein degradation.
abstract: OBJECTIVE
  To quantitatively measure the increased expression of Akt2 and its phosphorylated form (p-Akt) in oral cancer cell lines and investigate the post-translational mechanism for Akt2 and p-Akt overexpression.
  
  
  METHODS
  Three oral cancer cell lines and three cell lines of primary human oral keratinocytes (HOKs) were cultured and the degrees of Akt2 and p-Akt expression was evaluated by immunoblot analysis and flow cytometry. Each cell line was incubated with cycloheximide, an inhibitor of new protein synthesis, for various times to quantitatively determine the remaining expression levels of Akt2 and p-Akt by flow cytometry. The localization of Akt2 and p-Akt was assessed by immunofluorescence.
  
  
  RESULTS
  The levels of Akt2 and p-Akt proteins were significantly higher in cancer cell lines than those in HOKs (P < 0.05). When the new protein synthesis was blocked by cycloheximide treatment, the degradation rate of Akt2 and p-Akt in oral cancer cells was significantly lower than that in HOKs (P < 0.05). Both Akt2 and p-Akt were more intensely stained in the cytoplasm of cancer cells, whereas HOKs expressed Akt2 and p-Akt only minimally.
  
  
  CONCLUSIONS
  Both Akt2 and p-Akt were overexpressed in oral cancer cells, which may be partly explained by a reduced rate of protein degradation in order to maintain high cytosolic levels.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Prakasit
authors.initials: P
authors.lastname: Archewa
authors.affiliation: Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Supansa
authors.initials: S
authors.lastname: Pata
authors.affiliation: Department of Oral Biology and Diagnostic Sciences, Center of Excellence in Oral and Maxillofacial Biology, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Pareena
authors.initials: P
authors.lastname: Chotjumlong
authors.affiliation: Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Chayarop
authors.initials: C
authors.lastname: Supanchart
authors.affiliation: Department of Oral Biology and Diagnostic Sciences, Center of Excellence in Oral and Maxillofacial Biology, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Suttichai
authors.initials: S
authors.lastname: Krisanaprakornkit
authors.affiliation: Department of Oral Biology and Diagnostic Sciences, Center of Excellence in Oral and Maxillofacial Biology, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Anak
authors.initials: A
authors.lastname: Iamaroon
mesh_terms: D015153:Blotting, Western; D045744:Cell Line, Tumor; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism; D009062:Mouth Neoplasms / Q000378:metabolism*; D010766:Phosphorylation; D059748:Proteolysis; D051057:Proto-Oncogene Proteins c-akt / Q000032:analysis / Q000378:metabolism*
chemical_list: C494921:AKT2 protein, human; D051057:Proto-Oncogene Proteins c-akt
keywords: Akt2; oral cancer; p-Akt; protein degradation