Abstract 2325: Destruction of circulating tumor cells by fluid shear stresses generated in a microfluidic system

Abstract

Abstract Circulating tumor cells (CTCs) are mainly responsible for the cause of cancer metastasis. Although most CTCs can be destroyed by the bloodstream, some of them can still manage to withstand hemodynamic shear stress in blood stream. To study the effects of fluidic micro-environment on CTCs, we designed a microfluidic system that can produce various levels of shear stress which can be generated in human artery under resting or exercise condition. We also generated three human breast cancer cell lines with increased ability to form lung metastases in nude mice (i.e. 213-M1A>231-M1>231-C3). All three cell lines can produce a fluorescence resonance energy transfer (FRET)-based sensor which can reveal apoptosis in real-time by changing its color from green to blue. Besides these, we also investigated the effects of shear stress on multiple types of cancer cells including lung cancer (A549), ovarian cancer (2008), breast cancer (UACC-893) and leukemia (K562). For all the cell lines, except the non-attached K562 cells, cells were cultured on petri-dishes, detached by trypsinization and re-suspended in a normal culture medium to a cell density of 2x105 cells/ml. One milliliter of this cell suspensions was circulated in our microfluidic system under the shear stresses of 15, 30, 45 and 60 dyne/cm2 for 2-18 h. The effects of shear stress on morphology and viability of CTCs were determined by FRET imaging microscopy and MTT assay. And the impact of shear stress on causing necrosis in CTCs were examined by propidium iodide (PI) staining and LDH assay. Our findings are summarized below: 1) High shear stress (SS60, 4 h) is more potent to destroy CTCs than low shear stress (SS15, 4 h). 2) High shear stress can destroy most of the CTCs via necrosis. 3) This high level of shear stress is theoretically achievable via physical exercise. 4) Highly metastatic 231-M1A cells are more resistant to high shear stress compared to less metastatic 231-C3 cells. 5) Leukemia K562 cells representing the white blood cells showed stronger resistance to high shear stress compared to the cancer cells tested in this study. We think these findings can help people to understand how metastatic CTCs resist shear force-induced cell death which are useful for designing more effective therapies against metastatic CTCs. Additionally, the finding that high shear stress is more effective to kill CTCs may inspire cancer patients to consider exercise as a way to increase their hemodynamic shear stress, consequently destroy CTCs and prevent cancer metastasis. Citation Format: Sagar Regmi, Afu Fu, Sierin Lim, Kathy Qian Luo. Destruction of circulating tumor cells by fluid shear stresses generated in a microfluidic system [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2325. doi:10.1158/1538-7445.AM2017-2325