AKT1 E17K in Colorectal Carcinoma Is Associated with BRAF V600E but Not MSI-H Status: A Clinicopathologic Comparison to PIK3CA Helical and Kinase Domain Mutants

Mol Cancer Res. 2015 Jun;13(6):1003-8. doi: 10.1158/1541-7786.MCR-15-0062-T. Epub 2015 Feb 24.


The PI3K/AKT/mTOR pathway is activated through multiple mechanisms in colorectal carcinoma. Here, the clinicopathologic and molecular features of AKT1 E17K-mutated colorectal carcinoma in comparison with PIK3CA-mutated colorectal carcinoma are described in detail. Interestingly, in comparison with PIK3CA mutants, AKT1 E17K was significantly associated with mucinous morphology and concurrent BRAF V600E mutation. Among PIK3CA mutants, exon 21 mutations were significantly associated with BRAF V600E mutation, MSI-H status, and poor differentiation, while exon 10 mutations were associated with KRAS/NRAS mutations. Three of four AKT1 mutants with data from both primary and metastatic lesions had concordant AKT1 mutation status in both. Both AKT1- and PIK3CA-mutant colorectal carcinoma demonstrated frequent loss of PTEN expression (38% and 34%, respectively) and similar rates of p-PRAS 40 expression (63% and 50%, respectively). Both patients with AKT1 E17K alone had primary resistance to cetuximab, whereas 7 of 8 patients with PIK3CA mutation alone experienced tumor shrinkage or stability with anti-EGFR therapy. These results demonstrate that AKT1 E17K mutation in advanced colorectal carcinoma is associated with mucinous morphology, PIK3CA wild-type status, and concurrent RAS/RAF mutations with similar pattern to PIK3CA exon 21 mutants. Thus, AKT1 E17K mutations contribute to primary resistance to cetuximab and serve as an actionable alteration.

Implications: This first systematic study of AKT1 and PIK3CA hotspot mutations and their association with cetuximab resistance and BRAF V600E mutation has important ramifications for the development of personalized medicine, particularly in identifying patient candidates for PI3K or AKT inhibitors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Antineoplastic Agents / therapeutic use
  • Cetuximab / therapeutic use
  • Class I Phosphatidylinositol 3-Kinases
  • Cohort Studies
  • Colorectal Neoplasms / drug therapy
  • Colorectal Neoplasms / genetics*
  • Colorectal Neoplasms / physiopathology
  • Drug Resistance, Neoplasm
  • ErbB Receptors / antagonists & inhibitors
  • ErbB Receptors / therapeutic use
  • Exons
  • Female
  • Humans
  • Male
  • Microsatellite Instability*
  • Middle Aged
  • Mutation Rate
  • Mutation*
  • Phosphatidylinositol 3-Kinases / genetics*
  • Protein Structure, Tertiary
  • Proto-Oncogene Proteins B-raf / genetics*
  • Proto-Oncogene Proteins c-akt / genetics*
  • Signal Transduction


  • Antineoplastic Agents
  • Phosphatidylinositol 3-Kinases
  • Class I Phosphatidylinositol 3-Kinases
  • PIK3CA protein, human
  • EGFR protein, human
  • ErbB Receptors
  • AKT1 protein, human
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf
  • Proto-Oncogene Proteins c-akt
  • Cetuximab