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  • ML334 br In the present study the


    In the present study, the in vitro assay of single-cell suspension dissociated from 3D spheroids was performed by the scratching assay. As shown in Fig. S13, SI and Table S5, MIA ML334 dissociated from 3D spheroids of 1:9 ratio had the farthest displacement (i.e. the straight distance from the farthest point to the start point) in 8 h. These data supported that single-cell suspension dissociated from 3D spheroids remained similar properties as in vivo model. However, the mean ve-locity of the MIA cells showed no significant differences in the co-cul-ture groups with various ratios. (Fig. S14, SI). Besides, the accelerated movement of MIA cells was observed in MIA-PSC co-spheroids in vitro. According ML334 to the fluorescence tracking, the co-cultured MIA cells did 
    not always move together with PSCs in the zebrafish, suggesting that the migration of MIA cells was increased not only through co-migration with PSCs, but also through the enhanced motility of MIA cells. Fur-thermore, the survival of MIA cells was improved by co-culture with PSCs, in consistence with the literature finding that PSCs offered the suitable microenvironment for cancer cell survival during metastasis [65]. Experimental findings in zebrafish provide additional evidence to support the current MIA-PSC 3D spheroids as an in vitro tumor model for PDAC.
    In spite of recent advances in chemotherapy and radiotherapy, surgical operation remains the only potential curative treatment for pancreatic cancer [66,67]. Novel therapeutic agents have so far not yet been developed, which may be ascribed partially to a lack of proper models that represent the tumor and its microenvironment in vivo. Despite that a few genetically engineered mouse models are available, the demand is still high in developing a physiologically relevant in vitro model for studying the tumor biology and drug resistance of pancreatic cancer. Gemcitabine was found effective for inhibiting pancreatic cancer cells both in culture alone and in xenograft induced by sub-cutaneous injection [68], but not as effective in the animal model re-
    ferred to as the KPC mouse (where the mouse was born with histolo-gically normal pancreatic, K-rasLSL.G12D/+, p53R172H/+, and PdxCre
    mice) or in human PDAC [68]. KPC mice are difficult to maintain and too expensive when used in drug screening for precision medicine. In the current study, we provide data indicating that the MIA:PSC (1:9) spheroids were more resistant to the combined gemcitabine and Abraxane treatment in vitro compared to spheroids of the other ratios. Our study revealed that PDAC cells (MIA) in spheroids expressed up-regulated levels of EMT changes, stemness, and drug-resistant asso-ciated genes, and demonstrated more drug resistance compared to those cultured alone. Therefore, PSCs in the current co-spheroid model did impose protection on PDAC cells from action of gemcitabine and Abraxane, which mimics the condition in pancreatic tumor of KPC mice and its microenvironment.
    In clinical, pancreatic cancer is surrounded with a large number of PSCs in an HA-rich environment [44]. The morphology of spheroids probably affects the permeability and penetration properties of drugs to the tumor. In this study, the special 3D spheroid structure of pancreatic cancer was spontaneously organized in the HA-rich environment. This spontaneous and rapid formation of 3D spheroids has mimicked the PDAC tumor characters such as migration or movement rate, tumor-igenesis, and anti-drug phenotype. It is important to establish tumor-like spheroids in a short time for drug screening. The simple and rapid 3D co-culture protocol on CS-HA plates may be used to explore the cellular characteristics of cancer cells and PSCs, which is not possible to achieve in a 2D state.