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Stromal PDGFR-α Activation Enhances Matrix Stiffness, Impedes Mammary Ductal Development, and Accelerates Tumor Growth.

Neoplasia (New York, N.Y.) (2017-05-16)
Anisha M Hammer, Gina M Sizemore, Vasudha C Shukla, Alex Avendano, Steven T Sizemore, Jonathan J Chang, Raleigh D Kladney, Maria C Cuitiño, Katie A Thies, Quinn Verfurth, Arnab Chakravarti, Lisa D Yee, Gustavo Leone, Jonathan W Song, Samir N Ghadiali, Michael C Ostrowski
ABSTRACT

The extracellular matrix (ECM) is critical for mammary ductal development and differentiation, but how mammary fibroblasts regulate ECM remodeling remains to be elucidated. Herein, we used a mouse genetic model to activate platelet derived growth factor receptor-alpha (PDGFRα) specifically in the stroma. Hyperactivation of PDGFRα in the mammary stroma severely hindered pubertal mammary ductal morphogenesis, but did not interrupt the lobuloalveolar differentiation program. Increased stromal PDGFRα signaling induced mammary fat pad fibrosis with a corresponding increase in interstitial hyaluronic acid (HA) and collagen deposition. Mammary fibroblasts with PDGFRα hyperactivation also decreased hydraulic permeability of a collagen substrate in an in vitro microfluidic device assay, which was mitigated by inhibition of either PDGFRα or HA. Fibrosis seen in this model significantly increased the overall stiffness of the mammary gland as measured by atomic force microscopy. Further, mammary tumor cells injected orthotopically in the fat pads of mice with stromal activation of PDGFRα grew larger tumors compared to controls. Taken together, our data establish that aberrant stromal PDGFRα signaling disrupts ECM homeostasis during mammary gland development, resulting in increased mammary stiffness and increased potential for tumor growth.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Collagenase from Clostridium histolyticum, for general use, Type I, 0.25-1.0 FALGPA units/mg solid, ≥125 CDU/mg solid
Sigma-Aldrich
Monoclonal Anti-Actin, α-Smooth Muscle, clone 1A4, ascites fluid
Sigma-Aldrich
Insulin from bovine pancreas, ≥25 USP units/mg (HPLC), powder