Laminar Shear Stress Promotes Nicotine-Induced Inflammation and Hemostatic Expression in Human Endothelial Cells

Fluid Shear Stress Induces Cell Cycle Arrest in Human Urinary Bladder Transitional Cell Carcinoma Through Bone Morphogenetic Protein Receptor-Smad1/5 Pathway

Introduction

Mechanical force generated from the interstitial fluid flow inside and surrounding tissue has been known to play a significant role in cancer pathophysiology. In this study, we aimed to investigate the role of laminar shear stress (LSS) in modulating the cell cycle of human bladder transitional carcinoma (BFTC-905) cells which are frequently stimulated by not only the interstitial fluid flow, but also the urine flow transported from kidney to bladder in the urinary tract.

Methods

The BFTC-905 cells were subjected to 0-12 dynes cm^-2 LSS for 1, 4, 8, or 12 h, respectively, followed by cellular and molecular assays for investigations of cell cycle regulation protein expressions, cell growth rates, and the potential mechanism.

Results

The results showed that the LSS with ≥ 8 dynes cm^-2 for ≥ 8 h significantly increased protein expressions of cyclin B1, Wee1, p21, and p-CDK1^(Tyr15) (p < 0.05 for each), but conversely decreased protein expressions of cyclin A2, D1, E1, and CDK-1, -2, -4, and -6 (p < 0.05 for each) in the BFTC-905 cells, indicating that a G₂/M cell cycle arrest was obtained after shearing stimulation. Furthermore, our data demonstrated that the LSS-induced G₂/M arrest and the corresponding changes in cell cycle regulatory protein expressions were modulated by bone morphogenetic protein (BMP) receptor-Smad1/5 signaling pathway.

Conclusions

Our findings provided evidences for the effect of mechanical microenvironment on urothelial cancer pathobiology and generated insights into mechanism of LSS-regulated bladder tumor cell cycle.

Laminar shear stress inhibits high glucose-induced migration and invasion in human bladder cancer cells

High glucose has been known to play a pathogenic role in the development and progression of bladder cancer in diabetics, whereas the leading cause of death in such patients is mainly attributed to hyperglycemia-enhanced metastasis. In addition to the impact of glucose, cancer cells may be affected by laminar shear stress (LSS) generated from interstitial, blood, and/or lymphatic fluid flows during metastasis. Although the effect of flow-induced mechanical force on cancer pathophysiology has been extensively investigated, very little is understood regarding the cells that are simultaneously stimulated by LSS and hyperglycemia. To address this issue, the influence of LSS on bladder cancer cell motility in a hyperglycemic environment was examined. Based on the results of cell movement and protein expression analyses, we found that both cell migration and invasion were up- and downregulated by 25 mM glucose and 12 dynes/cm² LSS, respectively. Furthermore, the motility of the cells with simultaneous hyperglycemic and LSS stimulations was significantly reduced compared with that of the cells stimulated by high glucose alone (P < 0.05), demonstrating that the LSS rather than hyperglycemia played the dominant role in regulation of cell motility. These results implied that LSS with an intensity ≥ 12 dynes/cm² may serve as a feasible tool to reduce bladder cancer motility in diabetics.