These results collectively demonstrate the relevant regulatory role of the mechano-chemical microenvironment in leading the preferential metastasis of tumor cells to specific tissues with high collagen concentrations and TFG- activity. Introduction The seed and soil theory1 was proposed in the late 19th century and has greatly influenced cancer research. in clear strand-like collective cell migration. Our results show that the concentration of the extracellular matrix is a key regulator of the formation of tumor clusters that affects their development and growth. In addition, chemical factors create a microenvironment that promotes the transformation of idle Rabbit Polyclonal to CaMK2-beta/gamma/delta tumor clusters into very active, invasive tumor structures. These results collectively demonstrate the relevant regulatory role of the mechano-chemical microenvironment in leading the preferential Pyridone 6 (JAK Inhibitor I) metastasis of tumor cells to specific tissues with high collagen concentrations and TFG- activity. Introduction The seed and soil theory1 was proposed in the late 19th century and Pyridone 6 (JAK Inhibitor I) has greatly influenced cancer research. Cancer cells represent cancer models provide numerous advantages over 2D models in studies aimed at exploring cancer malignancy24C26. For example, the differential matrix density responses of cancer cell lines have been correlated with tissue tropism27. Therefore, we used a simple collagen 3D culture system model to recreate metastatic conditions, and this allowed us to use live-cell microscopy to easily analyze differences in cell migration patterns. In particular, we found that the collagen concentration in the 3D matrix and the level of TGF- activation regulated differentiated patterns of cell migration and affected whether cells underwent individual or collective migration. Our results support the notion that the mechano-chemo-biological characteristics of the host tissue play crucial roles in determining the invasive capacity of tumor cells during metastasis. Results Higher collagen concentrations reduce cancer cell migration In this study, we sought to mimic the first key steps of tumor cell colonization to explore how different ECM environments affect cancer cell extravasation. First, we tested whether the migration of metastatic NSCLC cells was affected by different collagen concentrations. NCl-H1299 cells were selected as the model for metastatic cells in this study. Cells were seeded in hydrogels with different concentrations of ColI (2.5, 4 and 6?mg/mL). These collagen-based hydrogels were mechanically characterized in a previous study28. Here, we quantified their architecture (Table?1) and found that the stiffness, pore size and porosity of the collagen matrices were similar to the ranges found in various living tissues12,29,30. Table 1 Mean pore size (m), porosity (%) and storage shear modulus (Pa)28 of collagen hydrogels with different collagen concentrations after polymerization. ~ 1) pattern, and the diffusive coefficient as higher (indicating higher migratory persistence) (0.48 m2/min) for 2.5?mg/mL collagen. However, cell migration followed a confined motion (and intravital imaging experiments16, indicates that TGF- exerted a strong effect by causing cells to switch between a mode encompassing expansive growth with minimum movement to one defined by a strand migration state with high invasiveness. Additionally, mechanical forces exerted by tumor cluster on extracellular microenvironment are likely to play a pivotal role in this migration mode switch induced by TGF- and need further investigation. Hence, we show that overt tumor colonization can be recreated under these conditions in microfluidic devices. These results provide a new perspective on the mechanism by which tumor cells overcome steric hindrance in dense matrices. The increased invasiveness and Pyridone 6 (JAK Inhibitor I) higher survivability of cell clusters may play a role in high collagen-TGF- matrix tropism. Moreover, future approaches should use a diversity in tumor cell lines so that this hypothesis can be generalized and to unravel the molecular basis of the crosstalk observed between TGF- and collagen39. As a proof of concept, a highly metastatic breast cell line (MDA-MB-231), that produces bone metastases27, was also tested under conditions including a high collagen concentration (6?mg/mL) and treatment with TGF-. We achieved results (see Fig. Sup.?7) very similar to those found in NSCLCs. Therefore, and although this hypothesis should be explored in future experiments performed using many more and varied tumor cell lines, our results support the assumptions that a high collagen concentration regulates cluster growth and that TGF-beta mediates their capacity for invasion. In summary, the collagen concentration of biological fiber matrices represents a strong physical limitation on the Pyridone 6 (JAK Inhibitor I) capacity of cancer cells to migrate and proliferate, suggesting that collagen concentrations regulate the formation and growth of tumor spheroids in metastatic tumors. Thus, a combination including a high collagen concentration and an environment rich in TGF- will promote the capacity of tumor cells to invade host tissues (Fig.?7). Open in a separate window Figure 7 Graphical representation of the different cell morphologies observed in the.