Nicole Cruz-Reyes, PhD Candidate, Mayo Clinic FL
Activated fibroblasts in benign breast tissue are associated with subsequent breast cancer development
Abstract
Pseudoangiomatous stromal hyperplasia (PASH) is a benign breast lesion characterized by stromal myofibroblast accumulation. While most women with PASH do not develop breast cancer, a subset eventually does, often in the same breast, even after lesion removal. This pattern suggests a field effect, where microenvironmental alterations extend beyond the lesion, potentially influencing neighboring tissue. This study aims to identify fibroblasts within PASH-containing tissues that may create a pro-tumorigenic microenvironment.
We conducted a retrospective analysis of formalin-fixed, paraffin-embedded breast tissue samples from women diagnosed with PASH, comparing those who later developed breast cancer (cases) to those who remained cancer-free (controls). Using NanoString IO360/BC360 transcriptional profiling, multiplex immunofluorescence (MxIF), and spatial transcriptomics (NanoString CosMX SMI), we investigated fibroblast markers, epithelial proliferation, and extracellular matrix (ECM) composition.
Transcriptional profiling revealed upregulation of proliferation-associated genes in epithelial cells from cases. MxIF showed higher Ki-67 levels and clustered proliferating cells in cases. Activated fibroblasts expressing ITGB1 and PDGFRβ were increased and located closer to proliferating epithelial cells. Spatial transcriptomics indicated fibroblast activation and epithelial responses to increased tissue stiffness. Picrosirius red staining revealed enhanced collagen cross-linking and fibril thickening, suggesting greater ECM stiffness.
Our findings suggest activated fibroblasts remodel the ECM, increasing stiffness and promoting epithelial proliferation, potentially driving cancer development. This study introduces cancer-predisposing fibroblasts, highlighting early microenvironmental changes and potential intervention targets.
We conducted a retrospective analysis of formalin-fixed, paraffin-embedded breast tissue samples from women diagnosed with PASH, comparing those who later developed breast cancer (cases) to those who remained cancer-free (controls). Using NanoString IO360/BC360 transcriptional profiling, multiplex immunofluorescence (MxIF), and spatial transcriptomics (NanoString CosMX SMI), we investigated fibroblast markers, epithelial proliferation, and extracellular matrix (ECM) composition.
Transcriptional profiling revealed upregulation of proliferation-associated genes in epithelial cells from cases. MxIF showed higher Ki-67 levels and clustered proliferating cells in cases. Activated fibroblasts expressing ITGB1 and PDGFRβ were increased and located closer to proliferating epithelial cells. Spatial transcriptomics indicated fibroblast activation and epithelial responses to increased tissue stiffness. Picrosirius red staining revealed enhanced collagen cross-linking and fibril thickening, suggesting greater ECM stiffness.
Our findings suggest activated fibroblasts remodel the ECM, increasing stiffness and promoting epithelial proliferation, potentially driving cancer development. This study introduces cancer-predisposing fibroblasts, highlighting early microenvironmental changes and potential intervention targets.