Fluid shear stress stimulates breast cancer cells to display invasive and chemoresistant phenotypes while upregulating PLAU in a 3D bioreactor

Abstract

Breast cancer cells experience a range of shear stresses in the tumor microenvironment (TME). However most current in vitro three‐dimensional (3D) models fail to systematically probe the effects of this biophysical stimuli on cancer cell metastasis, proliferation, and chemoresistance. To investigate the roles of shear stress within the mammary and lung pleural effusion TME, a bioreactor capable of applying shear stress to cells within a 3D extracellular matrix was designed and characterized. Breast cancer cells were encapsulated within an interpenetrating network hydrogel and subjected to shear stress of 5.4 dynes cm−2 for 72 hr. Finite element modeling assessed shear stress profiles within the bioreactor. Cells exposed to shear stress had significantly higher cellular area and significantly lower circularity, indicating a motile phenotype. Stimulated cells were more proliferative than static controls and showed higher rates of chemoresistance to the anti‐neoplastic drug paclitaxel. Fluid shear stress‐induced significant upregulation of the PLAU gene and elevated urokinase activity was confirmed through zymography and activity assay. Overall, these results indicate that pulsatile shear stress promotes breast cancer cell proliferation, invasive potential, chemoresistance, and PLAU signaling.

Upregulation of COX-2 in MCF7 Breast Cancer Cells When Exposed to Shear Stress

“…MCF7 cells were concentrated to 10 X 10 6 cells/mL before suspension into the agarose/collagen hydrogel. Hydrogels were polymerized as described previously [7]. Briefly, the interpenetrating network (IPN) hydrogel comprised of 3% w/v agarose and 500 µg/ml type I collagen.…”

“…Shear bioreactor construction, description, assembly, and use were described previously [7]. Briefly, continuous cell culture medium flow was provided from a peristaltic pump at a volumetric flow rate of 2.276 cm 3 /s.…”

“…Drug studies were performed on all experimental and control conditions to investigate the presence of chemotherapeutic resistance due to shear stress stimulation. A previously identified IC 50 concentration of paclitaxel (25 µM) was used to investigate drug resistance in cells exposed to shear stress [7,15,16].…”

“…Specific to metastatic breast cancer, an often overlooked aspect of the tumor microenvironment (TME) is the application of physiological mechanical stimuli such as compression, shear stress, stiffness, and 3D cell culture, all of which continuously influence cellular signaling and downstream effects. Breast cancer cells within the TME experience a wide range of shear stresses, including vascular blood flow, interstitial fluid flow, and fluid movement within pleural effusion [7]. These shear stress stimuli have been shown to promote cell motility, adhesion, and metastasis in breast cancer, as well as in a variety of other cancer types [8][9][10][11][12][13].…”

“…To address this critical need, we utilize our previously developed shear stress bioreactor [7] to stimulate MCF7 luminal A breast adenocarcinoma cells within a highly tunable 3D microenvironment. Consistent with our previous studies, we find that breast cancer cells stimulated for 24 hours alter their morphology via an increase in cellular area and a decrease in circularity.…”