Early involvement of the phosphatidylinositol 3-kinase/Akt pathway in lung cancer progression.
Signaling through the phosphatidylinositol 3-kinase (PI3-kinase) pathway has been associated with lung tumorigenesis. We examined the association between gene copy number of the PI3-kinase catalytic subunit alpha (PIK3CA) and phosphorylated Akt expression in invasive and preinvasive lung cancers. We sought to determine at what stage of tumor development gene copy number increase or phosphorylated Akt overexpression might affect tumor development. We assessed PIK3CA gene copy number by fluorescence in situ hybridization and expression of phosphorylated Akt by immunohistochemistry in 242 invasive and 43 preinvasive lung cancers and correlated our findings with clinical outcome. The PIK3CA was amplified in 70% of squamous carcinomas, 38% of large cell carcinomas, 19% of adenocarcinomas, and 67% of small cell lung cancers. Phosphorylated Akt overexpression was frequently observed, and strongly so in 12 to 17% of lung cancers depending on nuclear or cytoplasmic localization. Neither PIK3CA gene copy number nor phosphorylated Akt protein expression had prognostic significance. In preinvasive lesions, amplification of the PIK3CA and overexpression of phosphorylated Akt were associated with severe dysplasia and each other. These observations suggest frequent and early involvement of the PI3-kinase pathway in lung cancer.
Department of Medicine, Biostatistics Shared Resource, the Vanderbilt-Ingram Comprehensive Cancer Center, Vanderbilt University Medical Center, Nashville, TN 37232-6838, USA. pierre.massion@vanderbilt.edu
Pierre P
PP
Massion
Peter M
PM
Taflan
Yu
Y
Shyr
S M Jamshedur
SM
Rahman
Pinar
P
Yildiz
Bashar
B
Shakthour
Mary E
ME
Edgerton
Matthew
M
Ninan
Jeremiah J
JJ
Andersen
Adriana L
AL
Gonzalez
D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001707:Biopsy, Needle; D018450:Disease Progression; D004789:Enzyme Activation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D011336:Probability; D011379:Prognosis; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D046509:Tissue Culture Techniques
D014408:Biomarkers, Tumor; D019869:Phosphatidylinositol 3-Kinases