Microenvironment complexity and matrix stiffness regulate breast cancer cell activity in a 3D in vitro model

Abstract

Three-dimensional (3D) cell cultures represent fundamental tools for the comprehension of cellular phenomena both in normal and in pathological conditions. In particular, mechanical and chemical stimuli play a relevant role on cell fate, cancer onset and malignant evolution. Here, we use mechanically-tuned alginate hydrogels to study the role of substrate elasticity on breast adenocarcinoma cell activity. The hydrogel elastic modulus (E) was measured via atomic force microscopy (AFM) and a remarkable range (150–4000 kPa) was obtained. A breast cancer cell line, MCF-7, was seeded within the 3D gels, on standard Petri and alginate-coated dishes (2D controls). Cells showed dramatic morphological differences when cultured in 3D versus 2D, exhibiting a flat shape in both 2D conditions, while maintaining a circular, spheroid-organized (cluster) conformation within the gels, similar to those in vivo. Moreover, we observed a strict correlation between cell viability and substrate elasticity; in particular, the number of MCF-7 cells decreased constantly with increasing hydrogel elasticity. Remarkably, the highest cellular proliferation rate, associated with the formation of cell clusters, occurred at two weeks only in the softest hydrogels (E = 150–200 kPa), highlighting the need to adopt more realistic and a priori defined models for in vitro cancer studies.

Development of an Alginate Array Platform to Decouple the Effect of Multiparametric Perturbations on Human Pluripotent Stem Cells During Pancreatic Differentiation

“…In addition, there was a decrease in DNA content with increasing stiffness, likely due to the hydrogel physically inhibiting cell expansion. Similar results have been seen in alginate encapsulated breast cancer cells, neural stem cells, and hESC‐derived pancreatic cells …”

Morphometric analysis of a triple negative breast cancer cell line in hydrogel and monolayer culture environments

“…Non-cancerous mouse and human cell lines derived from normal cardiac and mammary epithelial tissue also have been shown to be morphologically distinct when cultured in hydrogel versus monolayer conditions, underscoring the global effect of culture substratum and environment on cell differentiation, regardless of tissue provenance (Emerman, Burwen & Pitelka, 1979; Streuli, Bailey & Bissell, 1991; Underwood et al, 2006; Liao et al, 2007; Pontes Soares et al, 2012). Research conducted using normal mammary gland epithelial cells and human breast cancer cells suggests that morphological changes visible in hydrogels may be due to regulation of cell growth and migration by matrix stiffness, and that cell viability decreases with increase in elasticity of hydrogels, with higher cell proliferation rate in soft hydrogels (Bissell & Barcellos-Hoff, 1987; Cavo et al, 2016). These intriguing observations raise questions about the mechanisms that promote HCC70 cell division in Geltrex™, a topic for future investigations using proliferation markers such as Ki67 (Pan et al, 2017).…”

“…3D cell culture systems typically incorporate scaffold materials, such as hydrogels, due to their similarity to in vivo conditions, especially to pathologies like cancer, as opposed to 2D models (Li, Fan & Houghton, 2007; Whiteside, 2008; Tibbitt & Anseth, 2009; Pontes Soares et al, 2012; Lovitt, Shelper & Avery, 2014; Xu et al, 2014). As a result, these 3D cultures may provide a powerful platform for anti-cancer drug screening (Herrmann et al, 2014; Xu, Farach-Carson & Jia, 2014; Zanoni et al, 2016; Cavo et al, 2016). …”

Mechanical Heterogeneity in the Bone Microenvironment as Characterised by Atomic Force Microscopy

“…It is increasingly clear that mechanical properties and forces play an essential role in controlling many aspects of cell biology of tissues and organs including growth, migration, differentiation, homeostasis and communication (1–3). How these fundamental cellular processes are influenced by such forces requires an understanding of the mechanical properties at a subcellular scale but in the context of the tissue, organ, or even the whole organism.…”