Knock in of the AKT1 E17K mutation in human breast epithelial cells does not recapitulate oncogenic PIK3CA mutations

Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA.
Oncogene (Impact Factor: 8.46). 04/2010; 29(16):2337-45. DOI: 10.1038/onc.2009.516
Source: PubMed


An oncogenic mutation (G49A:E17K) in the AKT1 gene has been described recently in human breast, colon, and ovarian cancers. The low frequency of this mutation and perhaps other selective pressures have prevented the isolation of human cancer cell lines that harbor this mutation thereby limiting functional analysis. Here, we create a physiologic in vitro model to study the effects of this mutation by using somatic cell gene targeting using the nontumorigenic human breast epithelial cell line, MCF10A. Surprisingly, knock in of E17K into the AKT1 gene had minimal phenotypic consequences and importantly, did not recapitulate the biochemical and growth characteristics seen with somatic cell knock in of PIK3CA hotspot mutations. These results suggest that mutations in critical genes within the PI3-kinase (PI3K) pathway are not functionally equivalent, and that other cooperative genetic events may be necessary to achieve oncogenic PI3K pathway activation in cancers that contain the AKT1 E17K mutation.

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    • "The underlying molecular mechanisms of PI3K-driven oncogenesis are still unclear. Although AKT is largely regarded as the dominant mediator of oncogenic PI3K signaling [2], recent studies suggest that the link between PI3K and AKT can be uncoupled [15] [16] [17] [18]. For example, PDK1, but not AKT, is activated in some breast cancers with PIK3CA mutations [15] (Figure 1). "
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