Division of Applied Life Science, Graduate School of Engineering, Sojo University, Ikeda, Kumamoto, Japan.
J Biosci Bioeng. 2011 May;111(5):590-3. doi: 10.1016/j.jbiosc.2011.01.006. Epub 2011 Feb 26.
Human hepatic cancer cells, HepG2, formed spheroids on a poly-L-glutamic acid-coated dish. Doxorubicin (DOX) efflux activity of the cells in spheroid culture was higher than that in monolayer culture due to the higher expression of MDR1 protein of the cells in spheroids compared with those in monolayer. The amount of MDR1 per cell in spheroids was similar to that of hepatic tumor tissue in vivo. Consequently, it was suggested that the drug efflux activity of cells in spheroid culture reflected the activity of hepatic cancer cells. Furthermore, the IC(50) of DOX and epirubicin (EPI) in HepG2 cells, both of which are known to be exported by MDR1, were higher in spheroid compared with monolayer cells, while IC(50) of 5-fluorouracil (5-FU), which is not exported by MDR1 protein, was almost the same in both types of culture. The higher IC(50) of DOX and EPI in HepG2 cells in spheroid culture was associated with a higher efflux activity of the drugs in the spheroid-cultured cells, which appeared to reflect the IC(50) of DOX and EPI in cancer cells in vivo. Therefore, a spheroid culture of hepatic cancer cells seems to provide a promising cell-based in vitro assay system for examining the proper IC(50) values of anticancer agents that would reflect the drug resistance of cancer cells in vivo. In addition, the system would be useful in screening for inhibitors of MDR1 activity, which will help to overcome the multidrug resistance of cancer cells.
人肝癌细胞 HepG2 在聚-L-谷氨酸涂层培养皿上形成球体。由于球体中的细胞 MDR1 蛋白表达较高，与单层培养中的细胞相比，球体培养中的细胞对阿霉素（DOX）的外排活性更高。球体中每个细胞的 MDR1 量与体内肝肿瘤组织相似。因此，有人认为球体培养中细胞的药物外排活性反映了肝癌细胞的活性。此外，两种已知由 MDR1 外排的药物 DOX 和表阿霉素（EPI）在 HepG2 细胞中的 IC50 在球体中比在单层细胞中更高，而 5-氟尿嘧啶（5-FU）的 IC50 （不由 MDR1 蛋白外排）在两种培养类型中几乎相同。DOX 和 EPI 在球体培养中的 HepG2 细胞中的较高 IC50 与药物在球体培养细胞中的较高外排活性有关，这似乎反映了体内癌症细胞中 DOX 和 EPI 的 IC50。因此，肝癌细胞的球体培养似乎为检查抗癌药物的适当 IC50 值提供了一种有前途的基于细胞的体外检测系统，该系统将反映体内癌症细胞的耐药性。此外，该系统在筛选 MDR1 活性抑制剂方面将非常有用，这将有助于克服癌症细胞的多药耐药性。
