Abstract 2344: 3D extracellular stiffness cues drive localized changes in gene expression

Abstract

Abstract The stiffness of the extracellular matrix (ECM) stimulates mechanotransduction pathways that regulate tissue development and tumor progression. We previously showed that a stiff ECM potentiates cell growth and survival, enhances cell migration to drive tumor cell invasion, and drives malignant progression of the mammary gland in culture and in vivo, but the specific transcriptional and molecular events that occur as cells acquire these phenotypic changes are not well understood. To clarify this process, we used expression microarrays, tandem mass spectrometry, and RNA sequencing to identify changes in gene expression levels, isoform usage, and protein abundance that occur as intact ascini respond to distinct stiffness environments. We found that in stiffer ECM conditions ascini acquire consistent changes in gene expression related to cell adhesion and mRNA splicing, and specifically induce the expression of a set of genes involved in epithelial cell differentiation that includes multiple SPRR and S100 proteins. Remarkably, these genes map to an apparent stiffness-mediated transcriptional hotspot on chromosome 1q21, a region containing elevated transcription in many cancers but whose activity has not been related to mechanotransduction. We then used a heuristic approach to identify additional candidate force-mediated transcriptional hotspots throughout the genome that contain multiple genes that are coordinately activated or silenced in response to elevated ECM stiffness. Provocatively, we find that genes whose expression levels are responsive to ECM stiffness cues are disproportionately located within chromosomal regions that associate with the nuclear lamina, suggesting that these transcriptional changes may be due in part to force-dependent alteration of genomic contacts with the nuclear envelope. These studies provide biological insight into the divergent cellular responses to distinct stiffness environments and suggest that genome regulatory responses to the force environment may specifically target distinct chromosomal regions via a mechanism that remains to be elucidated. Citation Format: Russell Bainer, Yoshihiro Yui, Shannon Mumenthaler, Parag Mallick, Ondrej Podlaha, Franziska Michor, Jan Liphardt, Jonathan Licht, Valerie Weaver. 3D extracellular stiffness cues drive localized changes in gene expression. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2344. doi:10.1158/1538-7445.AM2014-2344