title: Novel mutations of PIK3CA gene in head and neck squamous cell carcinoma.
abstract: BACKGROUND
  HNSCC is the sixth most common human cancer globally. In Saudi Arabia, HNSCC accounts for seven percent of all newly diagnosed cancer cases. The PIK3CA is one of the most commonly mutated oncogene in human malignancies, including HNSCC.
  
  
  OBJECTIVE
  The objective of this study is to identify mutations in exon 9 and exon 20 of the PIK3CA gene among Saudi HNSCC patients, determine the frequency of these mutations and correlate with clinical and pathological findings.
  
  
  METHODS
  Histopathologically confirmed paraffin embedded HNSCC tumor tissues from 48 patients were obtained. Capillary sequencing method was used to sequence exons 9 and 20 of the PIK3CA gene. Concurrently, the expression analysis of the PIK3CA and PTEN genes were performed using real-time PCR.
  
  
  RESULTS
  Sixty percent of the samples studied were of pharyngeal cancer. A total of seven mutations were identified in exons 9 and 20 of the PIK3CA gene in 14 HNSCC tumor tissue specimens. The seven mutations encompassed one hot spot mutation E542K, a common mutation T1025T and the five novel mutation comprising three missense and two silent mutations. Interestingly, eight out of the 14 samples with a mutation were of patients with pharyngeal cancer.
  
  
  CONCLUSIONS
  PIK3CA gene plays a crucial role in carcinogenesis in general and HNSCC in particular. The identification of five novel mutations suggest that Saudis may have different frequencies of somatic genetic alterations that may influence HNSCC compared to other populations.
authors.affiliation: Department of Internal Medicine, King Fahd Hospital of the University, University of Dammam, Al-Khobar, Kingdom of Saudi Arabia.
authors.forename: Ali M
authors.initials: AM
authors.lastname: Al-Amri
authors.affiliation: Institute for Research & Medical Consultation, University of Dammam, Dammam, Kingdom of Saudi Arabia.
authors.forename: Chittibabu
authors.initials: C
authors.lastname: Vatte
authors.affiliation: Institute for Research & Medical Consultation, University of Dammam, Dammam, Kingdom of Saudi Arabia.
authors.forename: Cyril
authors.initials: C
authors.lastname: Cyrus
authors.affiliation: Institute for Research & Medical Consultation, University of Dammam, Dammam, Kingdom of Saudi Arabia.
authors.forename: Shahanas
authors.initials: S
authors.lastname: Chathoth
authors.affiliation: Department of Pathology, King Fahd Hospital of the University, University of Dammam, Al-Khobar, Kingdom of Saudi Arabia.
authors.forename: Tariq Mohammad
authors.initials: TM
authors.lastname: Hashim
authors.affiliation: Department of Microbiology, University of Dammam, Dammam, Kingdom of Saudi Arabia.
authors.forename: Yehia S
authors.initials: YS
authors.lastname: Mohamed
authors.affiliation: Department of Internal Medicine, King Fahd Hospital of the University, University of Dammam, Al-Khobar, Kingdom of Saudi Arabia.
authors.forename: Rudaynah
authors.initials: R
authors.lastname: Al Ali
authors.affiliation: Department of Internal Medicine, King Fahd Hospital of the University, University of Dammam, Al-Khobar, Kingdom of Saudi Arabia.
authors.forename: Abir
authors.initials: A
authors.lastname: Alsaid
authors.affiliation: Institute for Research & Medical Consultation, University of Dammam, Dammam, Kingdom of Saudi Arabia.
authors.forename: Amein
authors.initials: A
authors.lastname: Al Ali
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D063646:Carcinogenesis / Q000235:genetics*; D002294:Carcinoma, Squamous Cell / Q000235:genetics*; D058534:Class I Phosphatidylinositol 3-Kinases; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006258:Head and Neck Neoplasms / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D051059:PTEN Phosphohydrolase / Q000096:biosynthesis / Q000235:genetics; D019869:Phosphatidylinositol 3-Kinases / Q000096:biosynthesis / Q000235:genetics*; D012529:Saudi Arabia; D015398:Signal Transduction / Q000235:genetics; D000077195:Squamous Cell Carcinoma of Head and Neck; D055815:Young Adult
chemical_list: D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human
keywords: HNSCC; PIK3CA; PTEN; gene expression; mutation; pharyngeal cancer