cancer; invasion; mechanotransduction; cancer associated fibroblasts ; extracellular matrix ; metastasis; tenascin; MKL1
Gurbuz Irem, Ferralli Jacqueline, Roloff Tim, Chiquet-Ehrismann Ruth, Asparuhova Maria B (2014), SAP domain-dependent Mkl1 signaling stimulates proliferation and cell migration by induction of a distinct gene set indicative of poor prognosis in breast cancer patients., in Molecular cancer
, 13, 22-22.
Scharenberg Matthias A, Pippenger Benjamin E, Sack Ragna, Zingg Dominik, Ferralli Jacqueline, Schenk Susanne, Martin Ivan, Chiquet-Ehrismann Ruth (2014), TGF-β-induced differentiation into myofibroblasts involves specific regulation of two MKL1 isoforms., in Journal of cell science
, 127(Pt 5), 1079-91.
Tucker Richard P, Ferralli Jacqueline, Schittny Johannes C, Chiquet-Ehrismann Ruth (2013), Tenascin-C and tenascin-W in whisker follicle stem cell niches: possible roles in regulating stem cell proliferation and migration., in Journal of cell science
, 126(Pt 22), 5111-5.
Brellier Florence, Martina Enrico, Degen Martin, Heuzé-Vourc'h Nathalie, Petit Agnès, Kryza Thomas, Courty Yves, Terracciano Luigi, Ruiz Christian, Chiquet-Ehrismann Ruth (2012), Tenascin-W is a better cancer biomarker than tenascin-C for most human solid tumors., in BMC clinical pathology
, 12, 14-14.
Brellier Florence, Martina Enrico, Chiquet Matthias, Ferralli Jacqueline, van der Heyden Michael, Orend Gertraud, Schittny Johannes C, Chiquet-Ehrismann Ruth, Tucker Richard P (2012), The adhesion modulating properties of tenascin-W., in International journal of biological sciences
, 8(2), 187-94.
Asparuhova Maria B, Ferralli Jacqueline, Chiquet Matthias, Chiquet-Ehrismann Ruth (2011), The transcriptional regulator megakaryoblastic leukemia-1 mediates serum response factor-independent activation of tenascin-C transcription by mechanical stress., in FASEB journal : official publication of the Federation of American Societies for Experimental Biolog
, 25(10), 3477-88.
Chiquet-Ehrismann Ruth, Orend Gertraud, Chiquet Matthias, Tucker Richard P, Midwood Kim S, Tenascins in stem cell niches., in Matrix biology : journal of the International Society for Matrix Biology
Background: By now it is well recognized that mechanical signals influence cellular functions and that mechanical signals can be transduced into biochemical signals, a mechanism termed mechanotransduction. Stretch-application to cells induces specific signaling pathways leading to specific gene expression patterns. There are many ways how stretch can be perceived by cells including stretch sensing by stretch activated ion channels leading e.g. to Ca2+ signaling or by stretch-induced conformational changes in proteins to expose new interaction sites for e.g. kinases or other signal transducing proteins. Ultimately, the cell will adapt to increased strain by remodeling of the cytoskeleton. Upon stretch, actin polymerization is induced leading to a decrease in G-actin levels. This favors the nuclear accumulation of the transcriptional regulator MKL1 which will function in fine tuning of the transcriptional response to stretch. We found in the precursor project that MKL1 is the major factor required for the stretch-induced tenascin-C expression and discovered that the mechanism of this induction is distinct from the known SRF-dependent induction of gene expression by MKL1. From our previous studies we also know that tenascin-C is highly over-expressed in cancer stroma and favors cell migration and invasion. Finally, recent data from the literature have indicated that the stiffness or rigidity of the cancer stroma is a crucial determinator of the invasive behavior of cancer cells and e.g. tissue stiffness is a bad prognostic factor in human breast cancer. Working Hypothesis: We postulate that mechanical stimulation of cells induces similar cellular responses as the contact of cells with rigid matrices does. Just like the cells react to exogenous mechanical strain by cytoskeletal stiffening, the rigidity or stiffness of the extracellular matrix will cause a matching cytoskeletal adaptation in cells contacting and probing this matrix. If the microenvironment is stiff, the cytoskeleton will contract, actin polymerizes and G-actin levels fall. This will induce signaling by the actin sensor MKL1 and result in the expression of tenascin-C as well as other proteins co-regulated with tenascin-C to be discovered.Specific Aims: We plan to analyze the mechanical details of the induction of tenascin-C by MKL1 and will extend this study to tenascin-W, since this new tenascin family member is also expressed in cancer stroma. Since we found that tenascin-C is induced by MKL1 indepently of SRF, but requiring the SAP domain of MKL1, we will investigate whether the SAP domain binds to specific promoter elements of tenascin-C and whether there are more genes regulated by the same mechanism. We will extend our studies from fibroblasts to normal as well as cancer epithelial cells and determine whether stretching these cells induces the same transcriptional program as when they are cultured within rigid matrices in vitro as well as in in vivo models.Experimental Design: We will use in vitro cultures of mouse fibroblasts, normal epithelial and cancer epithelial cells in 2D and 3D cultures as well as cultures on flexible silicone membranes for the analysis of stretch-induced effects. We will perform a screen for MKL1 target genes that are co-regulated with tenascin-C by transcript profiling approaches of stable cell strains expressing different MKL1 variants. We will confirm our in vitro results both in mouse tumor models as well as in human cancer tissue and other human diseases accompanied by tissue stiffness, and high tenascin-C expression such as lung fibrosis, asthma and COPD.Expected Value of Proposed Project: We anticipate discovering novel sets of genes and signaling pathways important in stroma-mediated cancer progression by taking advantage of the development of a screening method using overexpression of an MKL1 variant specifically inducing a subset of genes co-regulated with tenascin-C.