Fibroblastic FAK activity promotes drastic ECM modification.Figure 6(A) Representative images of CK19 and α-SMA immunohistochemistry and Sirius red staining in serial sections of primary mouse tumour (graft of FAK-WT or FAK-KD fibroblasts + tumours cells at 38 days after injection) at the invasive front. Scale bar, 100 µm. Bottom: schematic organization of the cells (tumour cells in brown, CAFs in yellow and non-transformed epithelial cells in beige). (B) Representative images of ECM deposition (stained using Alexa Fluor 488 succinimidyl ester (NHS)) generated by FAK-WT or -KD activated fibroblasts during migration. (C) Quantification of collagen I gel contraction (calculated based on photographed gels using the formula 100*(well diameter - gel diameter)/well diameter) induced by fibroblasts in presence or not of tumour cells , or by hCAF in presence or not of FAK inhibitor (FAK-I, 1µM) (D) Quantification of the percentage change of Y397 FAK, total FAK, collagen I (coll I), collagen III (coll III), collagen IV (coll IV), LOXL2, periostin (POSTN), osteopontin (OPN) expression by human CAFs treated or not (NT) with FAK inhibitor (1µM), based on immunofluorescence analyses. Values are means ± SEM obtained from at least 5 primary hCAFs, isolated from 5 to 12 different fresh human PDAC samples. (E) Collagen I, III and IV and periostin deposition are shown using heat map of the IF staining, and cell shapes are identified by white line. Characterization of the ECM-enriched fraction (matrisome analyses) from hCAFs treated or not with FAK-I by LC-MS/MS proteomics. (F) Pie charts display the relative proportion of each of the major classes of matrisome proteins in non-treated hCAFs (N = 3 biological replicates with 2 technical replicates/condition) versus FAK-I treated hCAFs (N = 3 biological replicates with 2 technical replicates/condition). Left: Normalized peptide abundance for collagens from hCAFs (each CAF duplicate is represented, CAF1 in blue, 2 in red and 3 in black) treated or not with FAK inhibitor. Right: Heatmap of the collagen modifications in the 3 hCAFs upon FAK inhibition in hCAFs. The value of log2 fold-change between FAK inhibitor treated CAFs and non-treated CAFs for each protein was indicated by the colored scale, with red indicating increased expression while blue implies decreased expression. For each CAFs and each protein, log2 fold-change was calculated based on 2 technical replicates per condition Left: Normalized peptide abundance for proteoglycans (H) from hCAFs (each CAF duplicate is represented, CAF1 in blue, 2 in red and 3 in black) treated or not with FAK inhibitor. Right: Heatmap of the proteoglycan (H) modifications in the 3 hCAFs upon FAK inhibition in hCAFs. The value of log2 fold-change between FAK inhibitor treated CAFs and non-treated CAFs for each protein was indicated by the colored scale, with red indicating increased expression while blue implies decreased expression. For each CAFs and each protein, log2 fold-change was calculated based on 2 technical replicates per condition (I) Normalized peptide abundance for glycoproteins from hCAFs treated or not with FAK-I. (J) Heatmap of the glycoprotein modifications upon FAK-I in hCAFs. (K) Normalized peptide abundance for "matrisome-associated" protein division: ECM-affiliated proteins, Secreted factors, and ECM regulators from hCAFs treated or not with FAK inhibitor. (L) Left: Representative pictures of β1 integrin activation (red) of tumour cells, upon adhesion to either ECM deposited from non-treated CAFs or treated with FAK-I for 7 days, analyzed by IF. Merge: activated β1 integrin (red), phalloidin (green), dapi (blue). Right: quantification of the number of integrin β1 activated cluster per cells and size of those clusters.