Gaggioli 2007 - A RT I C L E S Fibroblast-led collective...

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© 200 7 Nature Publishing Group A RT I C L E S Fibroblast-led collective invasion of carcinoma cells with differing roles for RhoGTPases in leading and following cells Cedric Gaggioli 1 , Steven Hooper 1 , Cristina Hidalgo-Carcedo 1 , Robert Grosse 2 , John F. Marshall 3 , Kevin Harrington 4 and Erik Sahai 1,5 Imaging of collectively invading cocultures of carcinoma cells and stromal fibroblasts reveals that the leading cell is always a fibroblast and that carcinoma cells move within tracks in the extracellular matrix behind the fibroblast. The generation of these tracks by fibroblasts is sufficient to enable the collective invasion of the squamous cell carcinoma (SCC) cells and requires both protease- and force-mediated matrix remodelling. Force-mediated matrix remodelling depends on integrins α 3 and α 5, and Rho- mediated regulation of myosin light chain (MLC) activity in fibroblasts, but these factors are not required in carcinoma cells. Instead, carcinoma cells use Cdc42 and MRCK (myotonic dystrophy kinase-related CDC42-binding protein kinases) mediated regulation of MLC to follow the tracks generated by fibroblasts. The collective invasion of carcinoma cells has been noted by patholo- gists for many years 1,2 , but remains poorly understood. It has also been observed that, in many cases, invasive carcinomas retain many epithelial markers and do not upregulate mesenchymal markers; for example, collectively invading SCC cells frequently retain localization of the cell adhesion protein p120 catenin to sites of cell–cell contact 3 . A recent study has shown that MT1-MMP (MMP14) is required to mediate matrix proteolysis during collective invasion; however, this study used cells that were either of mesenchymal origin (HT1080) or had upregu- lated mesenchymal markers (MDA-MB-231) 4 . Mesenchymal cells (such as fibroblasts) are capable of matrix remodelling, and stromal fibro- blasts within tumours can promote tumour progression. Here, we use an ‘organotypic’ culture model to bring these observations together. SCC cells that retain epithelial markers are unable to remodel the surround- ing matrix, but instead follow behind stromal fibroblasts that remodel the extracellular matrix (ECM). We further determine differing require- ments for integrins and RhoGTPases in leading and following cells. RESULTS Stromal fibroblasts lead collective cancer cell invasion To study the invasion of SCC cells, a culture system that closely mimics the physiological situation was used 2,5 . SCC cells are grown on top of a dense matrix predominantly composed of fibrillar collagen I, with lesser amounts of laminins and collagen IV. These cultures are supported by a metal bridge to ensure that the upper surface is exposed to air and CO 2 , whereas the lower surface is in contact with media (see Supplementary Information, Fig. S1a). When SCC cells are cultured in these conditions they show aber- rant differentiation, but remain on top of the matrix (Fig. 1a). Introduction of fibroblasts isolated from either oral or vulval squamous cell carcinomas
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This note was uploaded on 08/17/2009 for the course 26CB 880 taught by Professor Khan during the Spring '07 term at University of Cincinnati.

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Gaggioli 2007 - A RT I C L E S Fibroblast-led collective...

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