A subset of myofibroblastic cancer-associated fibroblasts regulate collagen fiber elongation, which is prognostic in multiple cancers

Abstract

// Christopher J. Hanley 1 , Fergus Noble 1 , Matthew Ward 1 , Marc Bullock 1 , Cole Drifka 3 , Massimiliano Mellone 1 , Antigoni Manousopoulou 2 , Harvey E. Johnston 2 , Annette Hayden 1 , Steve Thirdborough 1 , Yuming Liu 3 , David M. Smith 1 , Toby Mellows 1 , W. John Kao 3 , Spiros D. Garbis 1, 2 , Alex Mirnezami 1 , Tim J. Underwood 1 , Kevin W. Eliceiri 3, * , Gareth J. Thomas 1, * 1 Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK 2 Clinical and Experimental Sciences Unit, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK 3 Laboratory for Optical and Computational Instrumentation (LOCI), Department of Biomedical Engineering, University of Madison, Wisconsin 53706, USA * These authors contributed equally to this work Correspondence to: Gareth J. Thomas, e-mail: g.thomas@soton.ac.uk Keywords: extracellular matrix, collagen, cancer associated fibroblasts, tumor microenvironment, second harmonic generation Received: July 22, 2015      Accepted: December 05, 2015      Published: December 23, 2015 ABSTRACT Collagen structure has been shown to influence tumor cell invasion, metastasis and clinical outcome in breast cancer. However, it remains unclear how it affects other solid cancers. Here we utilized multi-photon laser scanning microscopy and Second Harmonic Generation to identify alterations to collagen fiber structure within the tumor stroma of head & neck, esophageal and colorectal cancers. Image segmentation algorithms were then applied to quantitatively characterize these morphological changes, showing that elongated collagen fibers significantly correlated with poor clinical outcome (Log Rank p < 0.05). We used TGF-β treatment to model fibroblast conversion to smooth muscle actin SMA-positive cancer associated fibroblasts (CAFs) and found that these cells induce the formation of elongated collagen fibers in vivo . However, proteomic/transcriptomic analysis of SMA-positive CAFs cultured ex-vivo showed significant heterogeneity in the expression of genes with collagen fibril organizing gene ontology. Notably, stratifying patients according to stromal SMA-positivity and collagen fiber elongation was found to provide a highly significant correlation with poor survival in all 3 cancer types (Log Rank p ≤ 0.003). In summary, we show that increased collagen fiber length correlates with poor patient survival in multiple tumor types and that only a sub-set of SMA-positive CAFs can mediate the formation of this collagen structure.