Distinguishing High-Metastasis-Potential Circulating Tumor Cells through Fluidic Shear Stress in a Bloodstream-Like Microfluidic Circulatory System

Circulating tumor cells (CTCs) play a critical role as initiators in tumor metastasis, which unlocks an irreversible process of cancer progression. Regarding the fluid environment of intravascular CTCs, a comprehensive understanding of the impact of hemodynamic shear stress on CTCs is of profound significance but remains vague. Here, we report a microfluidic circulatory system that can emulate CTC microenvironment to research responses of typical liver cancer cells to varying levels of fluid shear stress (FSS). We find that survived HepG2 cells in the microfluidic circulatory system exhibit marked overexpression on TLR4 and TPPP3 genes, which are shown to be associated with the colony formation, migration, and anti-apoptosis abilities of HepG2. Furthermore, overexpression of these two genes in another liver cancer cell line with low TLR4 and TPPP3 expression, SK-Hep-1 cells, by lentivirus-mediated transfection also confirm the critical role of TLR4 and TPPP3 on improving SK-Hep-1 cells’ colony formation, migration, and survival capability under fluid environment. Interestingly, in vivo study further shows SK-Hep-1 cells overexpressed with these genes have enhanced metastatic potential to liver and lung organs via tail vein injection in mouse models. These results reveal CTCs can adapt to fluid environment though altering genetic makeup and corresponding cellular behaviors, which may provide novel therapeutic strategies for cancer diagnosis and treatment.