Defining the Tumor Microenvironment by Integration of Im-munohistochemistry and Extracellular Matrix Targeted Imaging Mass Spectrometry

ABSTRACT: Breast stroma plays a significant role in breast cancer risk and progression yet remains poorly understood. In breast stroma, collagen is the most abundantly expressed protein and its increased deposition and alignment contributes to progression and poor prognosis. Collagen post-translation modifications such as hydroxylated-proline (HYP) control deposition and stromal organization. The clinical relevance of collagen HYP site modifications in cancer processes remains undefined due to technical issues accessing collagen from formalin-fixed, paraffin-embedded (FFPE) tissues. We previously developed a targeted approach for investigating collagen and other extracellular matrix proteins from FFPE tissue. Here, we hypothesized that immunohistochem-istry staining for fibroblastic markers would not interfere with targeted detection of collagen stroma peptides and could reveal peptide regulation influenced by specific cell types. Our initial work demonstrated that stromal peptide peak intensities when using MALD-IMS following IHC staining (αSMA, FAP, P4HA3 and PTEN) were comparable to serial sections of non-stained tissue. Analysis of histology-directed IMS using PTEN on breast tissues and TMAs revealed heteroge-neous PTEN staining patterns and suggestive roles in stromal protein regulation. This study sets the foundation for investigations of target cell types and their unique contribution to collagen regulation within extracellular matrix niches.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Breast

DISEASE(S): Breast Cancer

SUBMITTER: Jennifer Bethard  

LAB HEAD: Peggi M. Angel

PROVIDER: PXD028107 | Pride | 2022-02-15

REPOSITORIES: Pride