Shear stress induces internalization of E‐cadherin and invasiveness in metastatic oesophageal cancer cells by a Src‐dependent pathway

Abstract

Metastatic disease is dependent on tumor cell migration through the venous and lymphatic systems and requires dynamic rearrangement of adherens junctions. Endocytosis of cadherins is a key mechanism to dynamically arrange adherens junctions, signaling, and motility in tumor cells; however, the role of shear in regulating this process in metastatic cells is unknown. In this study, the role of shear in regulating cell surface expression of E-cadherin was investigated. M etastatic cell survival is dependent on adhesion and migration under shear stress encountered in the lymphatic and venous circulation. A key mechanism in this process involves altering cell surface expression of specific integrins and cadherins. Recent work has shown that both integrins and cadherins enter into early endosomes where they can be recycled back to the plasma membrane or degraded in lysosomes.(1,2)More recently, we (3) and others (4) have shown that exposure to physiological shear rates induces activation, translocation, and clustering of integrins in tumor cells; however, the precise role for shear in modulating cadherin expression in metastatic cells is unknown.Downregulation of cadherin-based adherens junctions is an important step in epithelial tumor invasion and metastasis, (5) and can occur through transcriptional silencing, (6) protein degradation,or through endocytosis. (8) Although transcriptional repression of the E-cadherin gene can result in loss of E-cadherin expression, more recent evidence suggests that post-translational mechanisms such as endocytosis may be involved in migratory behavior. (9) Accumulating evidence suggests that whenever epithelial cells need to become motile, E-cadherin is rapidly removed from the plasma membrane, where it can be recycled to sites of new cell-cell contacts.(10,11) Recently, Palacios et al. have shown that endocytosed E-cadherin enters into early Rab5-positive endosomes where it can be recycled rapidly back to the cell surface (time scale of 15-30 min) without undergoing degradation.(11) The Src family of tyrosine kinases have been implicated in regulating this process as they can phosphorylate tyrosine residues in the short intraplasmic tail of E-cadherin, thereby promoting their internalization by endocytosis.(12) In a recent study by Avizienyte et al., elevated Src in colon cancer cells was shown to alter adhesive properties that are associated with the disorganization of E-cadherin-dependent cell-cell contacts.(13) As loss of E-cadherin is associated with cellular invasion, (14) we hypothesized that shear may alter E-cadherin expression in metastatic tumor cells (OC-1 cells) in a Src-regulated manner.In the present study, the role of shear in the trafficking of E-cadherin within OC-1 cells was investigated. We show that shear induces internalization of E-cadherin into Rab5-positive endosomes, in contrast to static OC-1 cells where E-cadherin localizes specifically to cell-cell contacts. Src inhibition, using the specific inhibitor 4-amino-5-(4-methylpheny1)-7-(t-buty1) pyrazolo [3,4...

Adherens Junction Turnover: Regulating Adhesion Through Cadherin Endocytosis, Degradation, and Recycling

“…One recent study found that a non-junctional, presumably internalized, E-cadherin expression pattern was associated with poor survival in nasopharyngeal cancer (Xie et al, 2010). Another found Src-dependent E-cadherin internalization with shear stress in an oropharyngeal cancer cell line (Lawler et al, 2009). Increased E-cadherin internalization has also been found in a mouse model of UV-irradiation-induced squamous cell carcinoma (Brouxhon et al, 2007).…”

Periodic mechanical stress activates MEK1/2-ERK1/2 mitogenic signals in rat chondrocytes through Src and PLCγ1

“…As part of a mechanosensory protein complex, Src mediates the cellular response to mechanical stimuli in numerous non-chondrocytic cell types (23,37). In particular, Chaturvedi et al (14,15) have shown that, in the study of proliferation and migration of human Caco-2 intestinal epithelial cells mediated by rhythmic mechanical deformation, Src is a proximal kinase in the regulation of both proliferation and migration.…”

The physics of cancer: the role of physical interactions and mechanical forces in metastasis

“…By contrast, evidence suggests that low levels of shear stress, typical of the venous system, may have opposite effects on intracellular signalling and tumour cell function. For example, venous shear stress has been suggested to induce an EMT, as shown by the shear-mediated internalization of E-cadherin in metastatic oesophageal OC-1 tumour cells 115 . Moreover, exposure of free-flowing OC-1 cells to a shear rate of 200 s −1 increased their mobility and invasive capacity in vitro 115 .…”