SLC7A11转运体调控结直肠癌细胞氧化-抗氧化平衡与卡培他滨临床耐药机理研究

Capecitabine (CAPE) is a new oral drug of Fluorouracil (FU), which is widely used as a first-line treatment in the clinical therapy of gastrointestinal and breast cancer. However, individual differences of CAPE treatment are obvious, such as drug resistance developed in some patients after continuous use, and underlying mechanisms remain unknown. Preliminary studies found that significant differences in the oxidation-antioxidant balance and metabolic phenotypes between colorectal cancer cells SW480 ( CAPE-resistant) and LoVo (CAPE-sensitive). SLC7A11 transporter/cystine uptake, glutathione (GSH) biosynthesis and Pentose Phosphate Pathway (PPP) were inhibited in CAPE-resistant cells, which were contrary in CAPE-sensitive cells. It was suggested that there was a closely correlation between the sensitivity to CAPE and oxidation-anti-oxidation imbalance. Hence, based on integration of molecular biology, cellular pharmacokinetics and metabolomics, our proposal intends to investigate that effects of GSH biosynthesis regulated by SLC7A11/cystine pathway, nucleic acid synthesis regulated by PPP pathways on oxidation-antioxidant balance in colorectal cancer cells and CAPE efficacy. Combined with clinical samples, further studies were focused on searching for biomarkers related to efficacy and resistance of CAPE. We are looking forward to provide basis for resistance mechanism of CAPE, reversing resistance,predicting resistance in patients, achieving clinical accurate individualized treatment.

新型口服氟尿嘧啶类药物卡培他滨是临床胃肠道肿瘤、乳腺癌的一线治疗药物。然而，临床治疗个体差异明显，部分患者反复使用后产生耐药现象，其中机制不明。初步研究发现，结直肠癌细胞SW480（对卡培他滨治疗耐药）与LoVo（对卡培他滨治疗敏感）的氧化-抗氧化平衡及代谢表型均存在显著差异：耐药细胞中SLC7A11转运体/胱氨酸摄取、谷胱甘肽合成通路、PPP通路均处于抑制状态，而敏感细胞相反。提示肿瘤细胞氧化-抗氧化失衡与卡培他滨敏感性密切相关。课题拟采用分子生物学、细胞药代动力学与代谢组学结合方法，从离体细胞、在体动物水平探讨SLC7A11/胱氨酸调控谷胱甘肽合成、PPP通路调控核酸合成对结直肠癌细胞氧化-抗氧化平衡及卡培他滨药效的影响。结合临床样本，进一步探索与卡培他滨药效及耐药相关的标志物，为研究卡培他滨耐药机制、发现逆转耐药靶点、预测患者对卡培他滨的敏感性、实现临床精准个体化治疗提供依据。

近年来卡培他滨治疗胃肠道肿瘤已经出现了耐药现象。鉴于卡培他滨在体内特殊的代谢途径及其靶向杀伤肿瘤的效应，了解影响其药效敏感性的原因迫在眉睫。但由于卡培他滨在体内复杂的肝预代谢过程使得常规细胞培养系统难以在体外重现，目前没有卡培他滨离体研究的相关报道。针对此，本课题构建了肝/肠细胞共培养体系，并成功应用于CAP的药动学及药效学研究。结果表明 CAP 及其活性代谢产物在五种结直肠癌细胞内的动力学行为与其药效敏感性均呈现非线性关系。相应的代谢组学研究结果表明，结直肠癌代谢表型的差异，尤其是较为显著的 PPP 通路和氧化-抗氧化通路代谢通量的差异是细胞对卡培他滨产生耐受的关键因素。据此，该肝/肠细胞共培养模型技术有望应用于其他需要经肝脏代谢激活的前药的体外代谢和药效学研究。