Physical activity has been consistently linked to decreased incidence of breast cancer and a substantial increase in the length of survival of patients with breast cancer. However, the understanding of how applied physical forces directly regulate breast cancer remains limited. We investigated the role of mechanical forces in altering the chemoresistance, proliferation and metastasis of breast cancer cells. We found that applied mechanical tension can dramatically alter gene expression in breast cancer cells, leading to decreased proliferation, increased resistance to chemotherapeutic treatment and enhanced adhesion to inflamed endothelial cells and collagen I under fluidic shear stress. A mechanistic analysis of the pathways involved in these effects supported a complex signaling network that included Abl1, Lck, Jak2 and PI3K to regulate pro-survival signaling and enhancement of adhesion under flow. Studies using mouse xenograft models demonstrated reduced proliferation of breast cancer cells with orthotopic implantation and increased metastasis to the skull when the cancer cells were treated with mechanical load. Using high throughput mechanobiological screens we identified pathways that could be targeted to reduce the effects of load on metastasis and found that the effects of mechanical load on bone colonization could be reduced through treatment with a PI3Kγ inhibitor.
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−2for 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
- NSF-PAR ID:
- 10115415
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Biotechnology and Bioengineering
- Volume:
- 116
- Issue:
- 11
- ISSN:
- 0006-3592
- Page Range / eLocation ID:
- p. 3084-3097
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
more » « less
Abstract Due to the three-dimensional nature of the 3D bio-printed scaffolds, typical stagnant cell culturing methods don’t ensure entering medium inside areas or passing through the scaffolds. The bioreactor has frequently provided the required growth medium to encapsulated- and seeded-cells in 3D bio-printed scaffolds. To address this issue, we developed a customized perfusion bioreactor to supply the growth medium dynamically to the cells encapsulated or seeded in the scaffolds. The dynamic supply of fresh growth medium may help improve cell viability and proliferation. Because of its uniform nutrition distribution and flow-induced shear stress within the tissue-engineering scaffold, perfusion bioreactors have been used in a variety of tissue engineering applications. Including a modified setup of our designed bioreactor may improve the in vivo stimuli and conditions, eventually enhancing the overall performance of tissue regeneration. In this paper, we explored the response of fluid flow to certain types of scaffold pore geometries and porosities. We used a simulation technique to determine fluid flow turbulence through various pore geometries such as uniform triangular, square, diamond, circular, and honeycomb. We used variable pore sizes of the scaffold maintaining constant porosity to analyze the fluid flow. Based on the results, optimum designs for scaffolds were determined.
-
more » « less
Abstract A majority of breast cancer deaths occur due to metastasis of cancer cells to distant organs. In particular, brain metastasis is very aggressive with an extremely low survival rate. Breast cancer cells that metastasize to the brain can enter a state of dormancy, which allows them to evade death. The brain microenvironment provides biophysical, biochemical, and cellular cues, and plays an important role in determining the fate of dormant cancer cells. However, how these cues influence dormancy remains poorly understood. Herein, we employed hyaluronic acid (HA) hydrogels with a stiffness of ~0.4 kPa as an in vitro biomimetic platform to investigate the impact of biochemical cues, specifically alterations in RGD concentration, on dormancy versus proliferation in MDA‐MB‐231Br brain metastatic breast cancer cells. We applied varying concentrations of RGD peptide (0, 1, 2, or 4 mg/mL) to HA hydrogel surfaces and confirmed varying degrees of surface functionalization using a fluorescently labeled RGD peptide. Post functionalization, ~10,000 MDA‐MB‐231Br cells were seeded on top of the hydrogels and cultured for 5 days. We found that an increase in RGD concentration led to changes in cell morphology, with cells transitioning from a rounded to spindle‐like morphology as well as an increase in cell spreading area. Also, an increase in RGD concentration resulted in an increase in cell proliferation. Cellular dormancy was assessed using the ratio of phosphorylated extracellular signal‐regulated kinase 1/2 (p‐ERK) to phosphorylated p38 (p‐p38) positivity, which was significantly lower in hydrogels without RGD and in hydrogels with lowest RGD concentration compared to hydrogels functionalized with higher RGD concentration. We also demonstrated that the HA hydrogel‐induced cellular dormancy was reversible. Finally, we demonstrated the involvement of β1 integrin in mediating cell phenotype in our hydrogel platform. Overall, our results provide insight into the role of biochemical cues in regulating dormancy versus proliferation in brain metastatic breast cancer cells.
-
Perfusion applied to a 3D model of bone metastasis results in uniformly dispersed mechanical stimulimore » « less
Abstract Breast cancer most frequently metastasizes to the skeleton. Bone metastatic cancer is incurable and induces wide‐spread bone osteolysis, resulting in significant patient morbidity and mortality. Mechanical cues in the skeleton are an important microenvironmental parameter that modulate tumor formation, osteolysis, and tumor cell‐bone cell signaling, but which mechanical signals are the most beneficial and the corresponding molecular mechanisms are unknown. We focused on interstitial fluid flow based on its well‐known role in bone remodeling and in primary breast cancer. We created a full‐scale, microCT‐based computational model of a 3D model of bone metastasis undergoing applied perfusion to predict the internal mechanical environment during in vitro experimentation. Applied perfusion resulted in uniformly dispersed, heterogeneous fluid velocities, and wall shear stresses throughout the scaffold's interior. The distributions of fluid velocity and wall shear stress did not change within model sub‐domains of varying diameter and location. Additionally, the magnitude of these stimuli is within the range of anabolic mechanical signals in the skeleton, verifying that our 3D model reflects previous in vivo studies using anabolic mechanical loading in the context of bone metastasis. Our results indicate that local populations of cells throughout the scaffold would experience similar mechanical microenvironments.
-
High-Fidelity Simulation of Flows in Bone-Like Environment to Investigate the Growth of Cancer Cellsmore » « less
Abstract Metastatic cancer in bones is incurable, which causes significant mobility and mortality to the patients. In this work, we investigate the role of interstitial fluid flow on cancer cells' growth within the interconnected pores of human bone. In-vitro experiments were carried out in a bio-reactor which includes bone-like scaffold specimens. A pump is used to maintain a laminar flow condition inside the bioreactor to resemble fluid flow in bones. The scaffold specimens are harvested after 23 days in the bioreactor. The scaffold specimen is scanned with Micro-CT under the resolution of 70 micrometers. We created a full-scale 3D computational model of the scaffold based on the micro-CT data using the open-source software Seg3D and Meshmixer. Based on the geometrical models, we generated the computational grids using the commercial software Gridgen. We performed Computational Fluid Dynamics (CFD) simulations with the immersed boundary method (Gilmanov, Le, Sotiropoulos, JCP 300, 1, 2015) to investigate the flow patterns inside the pores of the scaffolds. The results reveal a non-uniform flow distribution in the vicinity of the scaffold. The flow velocity and the shear stress distributions inside the scaffold are shown to be convoluted and very sensitive to the pore sizes. Our future work will further quantify these distributions and correlate them to cancer cells' growth observed in the experiments.
