Constitutively Activated PI3K Accelerates Tumor Initiation and Modifies Histopathology of Breast Cancer

Authors

M. R. Sheen, Dartmouth College
J. D. Marotti, Dartmouth College
M. J. Allegrezza, The Wistar Institute
M. Rutkowski, The Wistar Institute
J. R. Conejo-Garcia, The Wistar Institute
S. Fiering, Dartmouth College

Document Type

Article

Publication Date

10-31-2016

Publication Title

Oncogenesis

Department

Geisel School of Medicine

Abstract

The gene encoding phosphatidylinositol 3-kinase catalytic subunit α-isoform (PIK3CA, p110α) is frequently activated by mutation in human cancers. Based on detection in some breast cancer precursors, PIK3CA mutations have been proposed to have a role in tumor initiation. To investigate this hypothesis, we generated a novel mouse model with a Cre-recombinase regulated allele of p110α (myristoylated-p110α, myr-p110α) along with p53fl/fl deletion and KrasG12D also regulated by Cre-recombinase. After instillation of adenovirus-expressing Cre-recombinase into mammary ducts, we found that myr-p110α accelerated breast tumor initiation in a copy number-dependent manner. Breast tumors induced by p53fl/fl;KrasG12D with no or one copy of myr-p110α had predominantly sarcomatoid features, whereas two copies of myr-p110α resulted in tumors with a carcinoma phenotype. This novel model provides experimental support for importance of active p110α in breast tumor initiation, and shows that the amount of PI3K activity can affect the rate of tumor initiation and modify the histological phenotype of breast cancer.

DOI

10.1038/oncsis.2016.65

Dartmouth Digital Commons Citation

Sheen, M. R.; Marotti, J. D.; Allegrezza, M. J.; Rutkowski, M.; Conejo-Garcia, J. R.; and Fiering, S., "Constitutively Activated PI3K Accelerates Tumor Initiation and Modifies Histopathology of Breast Cancer" (2016). Dartmouth Scholarship. 1697.
https://digitalcommons.dartmouth.edu/facoa/1697