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  • br In spite of recent advances


    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 VX 765 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.
    In summary, co-culture of pancreatic cancer cells and PSCs on CS-HA coated plates in vitro could generate tumor-like spheroids that ac-quire enhanced aggressive characteristics, including ECM phenotype, EMT marker expression, motility, cancer stem cell-like properties, and drug resistance, as shown in this study. The perspectives of generating 3D pancreatic tumor-like spheroids for drug screening in the precision medicine era are illustrated in Fig. 7. The patient specific tumor sam-ples (cancer and associated cells) can be obtained after surgery. The tumor cells are decellularized with enzymatic processes and applied to the CS-HA coated plates. Multiple 3D tumor-like spheroids are gener-ated within 48 h in vitro that mimic the pancreatic cancer micro-environment. The drug is then applied to the tumor-like spheroids and analyzed. The patient specific tumor spheroid-based assay in multiwell plates can be further developed as a tool for personalized medicine and a clinical high-throughput drug screening approach for anti-cancer drug discovery.
    This work was funded by Ministry of Science and Technology
    Fig. 7. Perspectives of 3D tumor-like spheroids for drug screening and design. The patient specific tumor samples are obtained after surgery. The tumor cells (cancer and associated cells) are decellularized with enzymatic processes and cultured on the CS-HA coated plates. The 3D tumor-like spheroids are generated in a multi-well plate at 48 h. The tumor-like spheroids mimic the pancreatic cancer microenvironment. The drug can be applied to the tumor-like spheroids and analyzed. The patient specific tumor spheroid based assay in multiwell plates can be developed as a high-throughput drug screening approach for anti-cancer drug discovery.
    Appendix A. Supplementary data
    M. Zalupski, N. Bahary, W. VX 765 Harris, Randomized phase II study of PEGPH20 plus nab‐paclitaxel/gemcitabine vs nab‐paclitaxel plus gemcitabine in patients with untreated, metastatic pancreatic ductal adenocarcinoma, J. Clin. Oncol. 35 (2017) 4008.
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