Validated prediction of pro-invasive growth factors using a transcriptome-wide invasion signature derived from a complex 3-D invasion assay. Mus musculus

The invasion of activated fibroblasts represents a key pathomechanism in fibrotic diseases, carcinogenesis and metastasis. Here, invading fibroblasts contribute to fibrotic extracellular matrix (ECM) formation and the initiation, progression, or resistance of cancer, respectively. To construct a transcriptome-wide signature of fibroblast invasion, we used a multiplex phenotypic 3D invasion assay using murine lung fibroblasts. Microarray-based gene expression profiles of invading and non-invading fibroblasts were highly distinct: 1049 genes were differentially regulated (>1.5-fold). An unbiased pathway analysis (Ingenuity) identified a significant enrichment for the functional clusters ‘invasion of cells’, ‘idiopathic pulmonary fibrosis (IPF)’ and ‘metastasis’. Particularly, matrix metalloprotease13 (MMP13), transforming growth factor (TGF)β1, Caveolin1 (Cav1), Phosphatase and Tensin Homolog (Pten), and secreted frizzled-related protein1 (Sfrp1) were among the highest regulated genes. In silico analysis by Ingenuity predicted TGFβ1, epidermal growth factor (EGF), fibroblast growth factor2 (FGF2), and platelet-derived growth factor (PDGF)-BB to induce invasion. As such, these growth factors were tested in the 3D invasion assay and displayed a significant induction of invasion, thus validating the transcriptome profile. Accordingly, our transcriptomic invasion signature describes the invading fibroblast phenotype in unprecedented detail and provides a tool for future functional studies of cell invasion and therapeutic modulation thereof. Overall design: We performed gene expression microarray analysis on the mouse lung fibroblast line MLg 2908. In a 3D collagen invasion assay we analysed invading and non-invading cells at different time points