title: Multiplexed imaging reveals heterogeneity of PI3K/MAPK network signaling in breast lesions of known PIK3CA genotype.
abstract: OBJECTIVE
  Activating genetic changes in the phosphatidylinositol-3-kinase (PI3K) signaling pathway are found in over half of invasive breast cancers (IBCs). Previously, we discovered numerous hotspot PIK3CA mutations in proliferative breast lesions. Here, we investigate the spatial nature of PI3K pathway signaling and its relationship with PI3K genotype in breast lesions.
  
  
  METHODS
  We identified PI3K phosphosignaling network signatures in columnar cell change (CCL), usual ductal hyperplasia (UDH), ductal carcinoma in situ (DCIS), and IBC in 26 lesions of known PIK3CA genotype from 10 human breast specimens using a hyperspectral-based multiplexed tissue imaging platform (MTIP) to simultaneously quantitate PI3K/MAPK pathway targets (pAKT473, pAKT308, pPRAS40, pS6, and pERK) in FFPE tissue, with single-cell resolution.
  
  
  RESULTS
  We found that breast lesional epithelia contained spatially heterogeneous patterns of PI3K pathway phosphoprotein signatures, even within microscopic areas of CCL, UDH, DCIS, and IBC. Most lesions contained 3-12 unique phosphoprotein signatures within the same microscopic field. The dominant phosphoprotein signature for each lesion was not well correlated with lesion genotype or lesion histology, yet samples from the same patient tended to group together. Further, 5 UDH/CCL lesions across different patients had a common phosphosignature at the epithelial-stromal interface (possible myoepithelial cells) that was distinct from both the adjacent lesional epithelium and distinct from adjacent stroma.
  
  
  CONCLUSIONS
  We present the first spatial mapping of PI3K phosphoprotein networks in proliferative breast lesions and demonstrate complex PI3K signaling heterogeneity that defies simple correlation between PIK3CA genotype and phosphosignal pattern.
authors: Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, 97201, USA.
authors: Thomas
authors: T
authors: Jacob
authors: Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, 97201, USA.|OHSU Center for Spatial Systems Bioscience, Portland, OR, 97201, USA.|The Knight Cancer Institute, Oregon Health & Science University, Portland, OR, 97239, USA.
authors: Joe W
authors: JW
authors: Gray
authors: The Knight Cancer Institute, Oregon Health & Science University, Portland, OR, 97239, USA.|Department of Pathology, Oregon Health & Science University, Portland, OR, 97239, USA.|Department of Pathology, Stanford University Medical Center, Stanford, CA, 94305, USA.
authors: Megan
authors: M
authors: Troxell
authors: Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR, 97201, USA. vuta@ohsu.edu.|OHSU Center for Spatial Systems Bioscience, Portland, OR, 97201, USA. vuta@ohsu.edu.|The Knight Cancer Institute, Oregon Health & Science University, Portland, OR, 97239, USA. vuta@ohsu.edu.
authors: Tania Q
authors: TQ
authors: Vu
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D018270:Carcinoma, Ductal, Breast / Q000235:genetics / Q000378:metabolism*; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000235:genetics / Q000378:metabolism*; D058534:Class I Phosphatidylinositol 3-Kinases / Q000235:genetics*; D005260:Female; D018740:Genetic Heterogeneity; D006801:Humans; D006965:Hyperplasia; D020935:MAP Kinase Signaling System; D008875:Middle Aged; D009154:Mutation; D010750:Phosphoproteins / Q000378:metabolism*; D000072760:Single Molecule Imaging / Q000379:methods*
chemical_list: D010750:Phosphoproteins; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human
keywords: Columnar cell change; Hyperspectral imaging; PIK3CA; Phosphatidylinositol-3-kinase; Usual ductal hyperplasia