Abstract 187: Breast cancer cells exhibit enhanced proliferation, invasion, PLAU expression and chemoresistance when exposed to fluid shear stress in an innovative 3D bioreactor
Authors: Novak Caymen , Horst Eric , Raghavan Shreya , Mehta Geeta 
Published: August 2018

Abstract
The cells within the mammary tumor microenvironment experience a range of shear stresses from both interstitial fluid flow, as well as, vascular blood flow, and this shear stress is increased as the tumor expands. Many in vitro models recapitulate the 3D microenvironment but fail to include physiological shear stress. To address this issue, a bioreactor capable of applying 3D shear stress to cells encapsulated within a 3D environment was designed, characterized, and utilized to investigate the impact of shear stimulation on breast cancer cell morphology, proliferation, gene expression, and chemoresistance. A shear bioreactor capable of applying variable 3D shear stress to hydrogel constructs was designed and fabricated in house. Shear stress of 4.92 dynes/cm2 was applied for 72 hours to MDA-MB-231, MDA-MB-468, and MCF7 breast cancer cells housed within an interpenetrating agarose-collagen type I hydrogel (IPN). The IPN hydrogel was characterized using SEM imaging and rheometric testing, and the viscoelastic modulus was determined to be 10 kPa, within the range of aggressive tumor microenvironments. Histological stains were evaluated for morphology. Immunohistochemistry staining was used for proliferation and protein evaluation. Changes in gene expression were monitored through qPCR analysis. The chemotherapeutic drug paclitaxel was investigated to observe changes in chemoresistance while under shear stress stimulation. Finally, the PLAU inhibitor amiloride was investigated for impact on cellular response to shear stress stimulus. All cell lines were found to have a significant increase in cellular area and a decrease in circularity when exposed to shear stress. Shear stimulated cells also displayed an increase in proliferation as quantified by Ki67 expression. qRTPCR analysis revealed a greater than 2-fold increase in the expression of PLAU, a common factor in breast cancer progression and metastasis. Preliminary results also show enhanced chemoresistance. Overall, shear stress stimulus was found to enhance the expression of PLAU, contribute to breast cancer proliferation, morphological changes, and chemoresistance. This bioreactor provides an ideal in vitro 3D platform for understanding the influence of shear stress stimulus on a variety of cell types and co-culture investigations.
Acknowledgements: This material is based upon work supported by the DOD OCRP Early Career Investigator Award W81XWH-13-1-0134, MIOCA and Rivkin Center for Ovarian Cancer grants to GM. This research was supported by the National Cancer Institute of the National Institutes of Health under award number P30CA046592. CMN is supported by the National Science Foundation Graduate Research Fellowship under Grant No. 1256260.
Citation Format: Caymen Novak, Eric Horst, Shreya Raghavan, Geeta Mehta. Breast cancer cells exhibit enhanced proliferation, invasion, PLAU expression and chemoresistance when exposed to fluid shear stress in an innovative 3D bioreactor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 187.