# Fibroblast dynamics during mammary oncogenesis: senescence, Wnt9a and beyond

## TL;DR

This paper explores how fibroblasts in the mammary gland change during breast cancer, highlighting the role of Wnt9a in causing cell senescence.

## Contribution

The study introduces a new single-cell atlas of mammary stromal cells and identifies Wnt9a's role in fibroblast senescence during breast cancer.

## Key findings

- Single-cell analysis reveals dysregulation in fibroblast lineages during breast cancer.
- Wnt9a induces senescence in cancer-associated myofibroblasts.
- Temporal profiling uncovers distinct fibroblast states in healthy and cancerous mammary glands.

## Abstract

Mammary gland fibroblasts are highly plastic and transition through distinct states during development and disease. A new study by Pascual et al (2025) provides a comprehensive single-cell atlas of murine mammary stromal cell hierarchies, revealing dysregulation of progenitor-driven fibroblast lineages in breast cancer and a senescence role of Wnt9a in cancer-associated myofibroblasts.

Recent temporal profiling of stromal fibroblast populations in the healthy and cancerous mouse mammary gland uncovers Wnt9a as a senescence inducer in cancer-associated myofibroblasts.