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PIK3R1 (p85α) is somatically mutated at high frequency in primary endometrial cancer

Mary E Urick1, Meghan L Rudd, Andrew K Godwin

  • 1Cancer Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, Maryland 20892, USA.

Cancer Research
|April 12, 2011
PubMed

Insights

Mutations in PIK3R1 are common in endometrial cancers, particularly in endometrioid types. These PIK3R1 mutations alter phosphoinositide 3-kinase (PI3K) signaling, offering new therapeutic targets.

Area of Science:

  • Oncology
  • Molecular Biology
  • Genetics

Background:

  • Phosphoinositide 3-kinase (PI3K) is a key therapeutic target in cancer.
  • Mutations in PIK3CA, encoding the PI3K p110α subunit, are prevalent in endometrial cancers.
  • The role of PIK3R1, encoding the PI3K p85α subunit, in endometrial carcinoma remains less understood.

Purpose of the Study:

  • To investigate the frequency and patterns of PIK3R1 mutations in endometrial carcinoma.
  • To compare PIK3R1 mutation status with PIK3CA, PTEN, and KRAS mutations.
  • To biochemically assess the functional impact of identified PIK3R1 mutations on PI3K signaling.

Main Methods:

  • Exonic sequencing of PIK3R1 in 42 endometrioid endometrial cancers (EECs) and 66 nonendometrioid endometrial cancers (NEECs).
  • Comparative analysis of mutation patterns with PIK3CA, PTEN, and KRAS.
  • Stable expression of PIK3R1 mutants in U2OS cells for coimmunoprecipitation and Western blotting analysis of p110α binding and phospho-AKT(Ser473) levels.

Main Results:

  • PIK3R1 mutations were found in 43% of EECs and 12% of NEECs.
  • Most mutations (93.3%) were located in the p85α-nSH2 and -iSH2 domains, with several recurrent mutations identified.
  • PIK3R1 mutations were significantly more frequent in PIK3CA-wild type EECs (70%) compared to PIK3CA mutant EECs (18%).
  • Five of seven tested PIK3R1 mutants demonstrated p110α binding and increased phospho-AKT(Ser473) levels, indicating pathway activation.

Conclusions:

  • PIK3R1 mutations represent a novel mechanism of PI3K pathway dysregulation in endometrial tumors.
  • These findings highlight PIK3R1 as a potential therapeutic target in endometrial cancer.
  • Further research is warranted to correlate PIK3R1 mutations with clinical outcomes and response to PI3K-targeted therapies.

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