Kurasaka Chinatsu, Ogino Yoko, Sato Akira
Department of Biochemistry and Molecular Biology, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
Department of Gene Regulation, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
Int J Mol Sci. 2021 Mar 13;22(6):2916. doi: 10.3390/ijms22062916.
5-Fluorouracil (5-FU) is a cornerstone drug used in the treatment of colorectal cancer (CRC). However, the development of resistance to 5-FU and its analogs remain an unsolved problem in CRC treatment. In this study, we investigated the molecular mechanisms and tumor biological aspects of 5-FU resistance in CRC HCT116 cells. We established an acquired 5-FU-resistant cell line, HCT116R. HCT116R cells were cross-resistant to the 5-FU analog, fluorodeoxyuridine. In contrast, HCT116R cells were collaterally sensitive to SN-38 and CDDP compared with the parental HCT16 cells. Whole-exome sequencing revealed that a cluster of genes associated with the 5-FU metabolic pathway were not significantly mutated in HCT116 or HCT116R cells. Interestingly, HCT116R cells were regulated by the function of thymidylate synthase (TS), a 5-FU active metabolite 5-fluorodeoxyuridine monophosphate (FdUMP) inhibiting enzyme. Half of the TS was in an active form, whereas the other half was in an inactive form. This finding indicates that 5-FU-resistant cells exhibited increased TS expression, and the TS enzyme is used to trap FdUMP, resulting in resistance to 5-FU and its analogs.
5-氟尿嘧啶（5-FU）是用于治疗结直肠癌（CRC）的一种基石药物。然而，对5-FU及其类似物产生耐药性仍是CRC治疗中一个尚未解决的问题。在本研究中，我们调查了CRC HCT116细胞中5-FU耐药的分子机制和肿瘤生物学方面。我们建立了一种获得性5-FU耐药细胞系HCT116R。HCT116R细胞对5-FU类似物氟脱氧尿苷具有交叉耐药性。相比之下，与亲本HCT16细胞相比，HCT116R细胞对SN-38和CDDP呈侧支敏感。全外显子测序显示，与5-FU代谢途径相关的一组基因在HCT116或HCT116R细胞中没有明显突变。有趣的是，HCT116R细胞受胸苷酸合成酶（TS）功能的调节，TS是一种抑制5-FU活性代谢物5-氟脱氧尿苷单磷酸（FdUMP）的酶。TS的一半处于活性形式，而另一半处于非活性形式。这一发现表明，5-FU耐药细胞表现出TS表达增加，并且TS酶用于捕获FdUMP，从而导致对5-FU及其类似物产生耐药性。
