AKT-independent signaling downstream of oncogenic PIK3CA mutations in human cancer.

Vasudevan KM, Barbie DA, Davies MA, Rabinovsky R, McNear CJ, Kim JJ, Hennessy BT, Tseng H, Pochanard P, Kim SY, Dunn IF, Schinzel AC, Sandy P, Hoersch S, Sheng Q, Gupta PB, Boehm JS, Reiling JH, Silver S, Lu Y, Stemke-Hale K, Dutta B, Joy C, Sahin AA, Gonzalez-Angulo AM, Lluch A, Rameh LE, Jacks T, Root DE, Lander ES, Mills GB, Hahn WC, Sellers WR, Garraway LA
Cancer Cell. 2009 16 (1): 21-32

PMID: 19573809 · PMCID: PMC2752826 · DOI:10.1016/j.ccr.2009.04.012

Dysregulation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway occurs frequently in human cancer. PTEN tumor suppressor or PIK3CA oncogene mutations both direct PI3K-dependent tumorigenesis largely through activation of the AKT/PKB kinase. However, here we show through phosphoprotein profiling and functional genomic studies that many PIK3CA mutant cancer cell lines and human breast tumors exhibit only minimal AKT activation and a diminished reliance on AKT for anchorage-independent growth. Instead, these cells retain robust PDK1 activation and membrane localization and exhibit dependency on the PDK1 substrate SGK3. SGK3 undergoes PI3K- and PDK1-dependent activation in PIK3CA mutant cancer cells. Thus, PI3K may promote cancer through both AKT-dependent and AKT-independent mechanisms. Knowledge of differential PI3K/PDK1 signaling could inform rational therapeutics in cancers harboring PIK3CA mutations.

MeSH Terms (15)

Breast Neoplasms Cell Line, Tumor Cell Survival Class I Phosphatidylinositol 3-Kinases Enzyme Activation Female Gene Expression Profiling Humans Mutation Neoplasms Phosphatidylinositol 3-Kinases Protein-Serine-Threonine Kinases Proto-Oncogene Proteins c-akt PTEN Phosphohydrolase Signal Transduction

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