PIK3CA mutations in head and neck squamous cell carcinoma.
OBJECTIVE
Recent studies have reported high frequencies of somatic mutations in the phosphoinositide-3-kinase catalytic alpha (PIK3CA) gene in several human solid tumors. Although gene amplifications of PIK3CA have been reported in head and neck squamous cell carcinoma (HNSCC), small mutation of the gene has not been evaluated in HNSCC previously. In this study, we examined the mutation frequency of PIK3CA in HNSCC.


METHODS
More than 75% of the somatic mutations of PIK3CA are clustered in the helical (exon 9) and kinase domains (exon 20). To investigate the possible role of PIK3CA in HNSCC tumorigenesis, exons 1, 4, 5, 6, 7, 9, and 20 of the gene were analyzed by direct genomic DNA sequencing in 38 HNSCC specimens.


RESULTS
We identified four missense mutations in the seven exons of PIK3CA from 38 HNSCC specimens (11%). Three of the four mutations (i.e., H1047R, E542K, and E545K) have been previously reported as hotspot mutations. The remaining novel mutation, Y343C, is identified at exon 4 nucleotide 1028 A --> G. Three of the four mutations were shown to be somatic, whereas the fourth mutation (H1047R) was identified in a cell line. Interestingly, three of the four mutations identified were in pharyngeal cancer samples.


CONCLUSIONS
These data provide evidence that oncogenic properties of PIK3CA contribute to the carcinogenesis of human head and neck cancers, especially in pharyngeal cancer. A specific kinase inhibitor to PIK3CA may potentially be an effective therapeutic reagent against HNSCC or pharyngeal cancer in particular.
Qiu
Wanglong
W
Department of Otolaryngology/Head and Neck Surgery, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
Schönleben
Frank
F
Li
Xiaojun
X
Ho
Daniel J
DJ
Close
Lanny G
LG
Manolidis
Spiros
S
Bennett
Boyce P
BP
Su
Gloria H
GH
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D002294:Carcinoma, Squamous Cell / Q000235:genetics*; D058534:Class I Phosphatidylinositol 3-Kinases; D006258:Head and Neck Neoplasms / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D020125:Mutation, Missense / Q000235:genetics*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D014407:Tumor Cells, Cultured
D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human