Unlike solid mechanics and structural mechanics, fluid mechanics involves the investigation of components that continually change their form and are in a constant state of motion
Unlike solid mechanics and structural mechanics, fluid mechanics involves the investigation of components that continually change their form and are in a constant state of motion. flow, is known to actively participate in proliferation, apoptosis, invasion, and metastasis of tumor cells. The present review discusses the progress and achievements in studies on tumor fluid microenvironment in recent years, especially fluid shear stress, on tumor metastasis, and presents directions for future study. modeling of the tumor fluid microenvironment has been faced with numerous technical challenges. In recent years, with the application of microfluidic technology and mechanical measurement methods in studies on cancer, developments in tumor fluid mechanics accelerated. Increasing evidence now indicates that fluid shear stress (FSS) is an essential factor affecting fluid mechanics, and its role in metastasis has received increasing attention. FSS is defined as the internal frictional pressure between moving layers in laminar flow. Additionally, FSS, the product of fluid viscosity and shear rate, is an important parameter of cellular stress in flowing liquid, measured in Newtons per square meter (N/m2) or dynes per square centimeter (dyn/cm2) . FSS is usually a key regulator of vascular endothelial phenotypes and to induce polarity in endothelial cell , cytoskeletal rearrangement , and post-translational modifications (e.g., phosphorylation, etc.) and gene expression . Liquid laminar flow is usually prevalent in biological systems and is usually categorized as blood, lymphoid, and interstitial flow. Tumor cells primarily encounter interstitial shear stress and blood shear stress during metastasis to the target organs. The former Almitrine mesylate plays a role in promoting tumor metastasis, lymphatic drainage, and anti-cancer drug delivery . Current evidence suggests that on tumorigenesis, blood shear stress has dual effects. It could promote tumor invasion and metastasis, adhesion, and extravasation under certain circumstances while  conversely, mechanically eliminating circulating tumor cells (CTCs) , and they promote cell cycle arrest in tumor cells . The development of related technology, four types of tumor-related fluid microenvironments and the mechanism of FSS in various stages of the tumor metastasis cascade are summarized herein to provide a Almitrine mesylate reference for subsequent studies on tumor fluid mechanics. Technological advancements in microfluidics In the past few decades, the need to explore the biological significance of mechanical force has led to the development of several innovative approaches. Furthermore, the emergence of pN-level mechanical measurement and visualization tools such as biofilm probes, traction force microscopy, and atomic pressure microscopy have shifted the focus from traditional biomechanics to mechanotransduction at the cellular and subcellular level , and the use of microfluidic chips and 4-dimensional flow magnetic resonance imaging to model and mechanical Cited2 microenvironments has received increasing attention [21,22]. The following sections focus on the advancements in fluid mechanic tools and their applications in studies on cancer (Table 1). These novel methods have enhanced the general understanding of the correlation between tumor metastasis and fluid shear stress. Table 1 Tools for the study of fluid mechanics of cancer model of fluid dynamics is still urgent for the development of mechanical technology. Tumor metastasis-related fluid microenvironment Tumor growth and metastasis are influenced by changes in the fluid microenvironment, such as interstitial flow, lymph flow, blood flow, and other organ-specific components. Interstitial flow The gradual flow of fluid in tumor tissues is known as interstitial flow. In a physiological state, most of the fluid that leaks out of capillaries is usually directed back to the capillaries, and only a fraction of fluid that passes through tumor tissues is recycled by the lymphatic vessels. The aforementioned process completes the exchange of material between the capillaries and the surrounding tissues and prevents the accumulation of fluid in interstitial spaces. In tumor tissues, however, it was reported that owing to the increased flow rate and high vascular permeability , interstitial pressure increased and therefore interstitial shear stress approached approximately 0.1 dyn/cm2 [13,37] (Determine 1). Under continuous flow of interstitial fluid Almitrine mesylate in an 3D culture, the migration rate of breast malignancy cells tended to increase . Munson [64,65]. Lee supported this conclusion by demonstrating that FSS (0.05 dyn/cm2) activated the ROCK-LIMK-cofilin signaling axis, inducing nuclear translocation of YAP1, and regulating transcription of metastasis-related genes in prostate cancer cells . Yangs team also verified that Cav-1 can activate the downstream PI3K Akt/mTOR pathway and promote metastasis of.