TABLE 1.
Physical cues encountered by cancer cells during the metastatic cascade.
| Physical force | Description |
|---|---|
| Compression | Pushing force applied to a structure. A growing tumor can apply pushing forces on the surrounding tissue, which in turn also causes compression on the tumor |
| Contact guidance | Describes the tendency of cells to change their orientation based on surrounding geometrical patterns, such as nano/microgrooves on substrates or the direction of ECM fibers |
| Elasticity | Describes the ability of a material to resist deformation and return to its original size and shape when external forces are removed. A material that is fully elastic recovers its size and shape immediately after the applied load is removed |
| Hydraulic resistance | Fluid pressure felt by a moving object from the surrounding fluid, which must flow to accommodate the object movement. Many factors can influence hydraulic resistance, including the viscosity of the surrounding fluid, the geometry in which the fluid is enclosed, and the presence of any obstacles to flow |
| Interstitial Fluid Pressure (IFP) | A pushing force exerted on an object immersed in interstitial fluid due to the presence of hydraulic pressure. The hydraulic pressure can arise from osmotic pressure in the fluid and also hydrostatic pressure from the presence of gravity. Osmotic pressure is the force arising from the entropy of mixing water with other solutes, which drives water flow from a low to a high concentration compartment, thereby increasing hydraulic pressure in the high concentration compartment |
| Shear stress | Shear stress arises from friction between layers of moving fluids or between solid and fluid layer interfaces. Shear stress can be experienced by a body floating in a fluid stream or along the wall of a fluid conduit, such as a blood vessel wall |
| Stiffness | The ratio between the applied force and the deformation of the object experiencing force. A stiffer object requires more applied force to achieve the same deformation |
| Tension | Pulling or stretching force exerted upon a structure. Tension is the opposite of compression. Stretching force on the membrane (tension) around an ion channel can activate the ion channel |
| Topography | Describes the arrangement of physical features that affect the roughness of a surface, including curvature, columns, grooves, and other nano/micro factors |
| Turbulent Flow | Fluid motion characterized by random fluctuations in pressure and velocity due to the irregular movement of fluid particles. In contrast, laminar flow describes the smooth movement of fluid in parallel layers with no disruptions |
| Viscoelasticity | Describes both the elastic and viscous properties of a material. Most biological materials are viscoelastic, rather than elastic, and exhibit a time-dependent delay in deformation and relaxation in response to external forces. Viscoelastic materials also dissipate a fraction of energy it took to deform them, resulting in some permanent deformation after external forces are removed |
| Viscosity | Describes the resistance of a fluid to change shape at a given flow rate (i.e., resistance to flow) due to internal friction between molecules in the fluid |