Department of Biochemistry, Kindai University Faculty of Medicine, Osakasayama, Osaka, Japan.
Graduate School of Medical Sciences, Kindai University Faculty of Medicine, Osakasayama, Osaka, Japan.
Mol Cancer Res. 2023 May 1;21(5):444-457. doi: 10.1158/1541-7786.MCR-22-0554.
Pancreatic ductal adenocarcinoma (PDAC) is one of the most life-threatening malignancies. Although the deoxycytidine analog gemcitabine has been used as the first-line treatment for PDAC, the primary clinical challenge arises because of an eventual acquisition of resistance. Therefore, it is crucial to elucidate the mechanisms underlying gemcitabine resistance to improve treatment efficacy. To investigate potential genes whose inactivation confers gemcitabine resistance, we performed CRISPR knockout (KO) library screening. We found that deoxycytidine kinase (DCK) deficiency is the primary mechanism of gemcitabine resistance, and the inactivation of CRYBA2, DMBX1, CROT, and CD36 slightly conferred gemcitabine resistance. In particular, gene expression analysis revealed that DCK KO cells displayed a significant enrichment of genes associated with MYC targets, folate/one-carbon metabolism and glutamine metabolism pathways. Evidently, chemically targeting each of these pathways significantly reduced the survival of DCK KO cells. Moreover, the pathways enriched in DCK KO cells represented a trend similar to those in PDAC cell lines and samples of patients with PDAC with low DCK expression. We further observed that short-term treatment of parental CFPAC-1 cells with gemcitabine induces the expression of several genes, which promote synthesis and transport of glutamine in a dose-dependent manner, which suggests glutamine availability as a potential mechanism of escaping drug toxicity in an initial response for survival. Thus, our findings provide insights into novel therapeutic approaches for gemcitabine-resistant PDAC and emphasize the involvement of glutamine metabolism in drug-tolerant persister cells.
Our study revealed the key pathways involved in gemcitabine resistance in PDAC, thus providing potential therapeutic strategies.
胰腺导管腺癌（PDAC）是最具致命性的恶性肿瘤之一。虽然脱氧胞苷类似物吉西他滨已被用作 PDAC 的一线治疗药物，但主要的临床挑战是因为最终会产生耐药性。因此，阐明导致吉西他滨耐药的机制对于提高治疗效果至关重要。为了研究潜在的基因，这些基因的失活赋予了吉西他滨耐药性，我们进行了 CRISPR 敲除（KO）文库筛选。我们发现脱氧胞苷激酶（DCK）缺陷是吉西他滨耐药的主要机制，CRYBA2、DMBX1、CROT 和 CD36 的失活略微赋予了吉西他滨耐药性。特别是，基因表达分析表明，DCK KO 细胞显示出与 MYC 靶标、叶酸/一碳代谢和谷氨酰胺代谢途径相关的基因显著富集。显然，化学靶向这些途径中的每一个都显著降低了 DCK KO 细胞的存活率。此外，在 DCK KO 细胞中富集的途径与 PDAC 细胞系和低 DCK 表达的 PDAC 患者样本中观察到的途径相似。我们进一步观察到，用吉西他滨短期处理亲本 CFPAC-1 细胞会诱导几种基因的表达，这些基因以剂量依赖的方式促进谷氨酰胺的合成和转运，这表明谷氨酰胺的可用性是逃避初始药物毒性的潜在机制对于生存的反应。因此，我们的发现为吉西他滨耐药性 PDAC 的新治疗方法提供了思路，并强调了谷氨酰胺代谢在耐药性持久细胞中的作用。
我们的研究揭示了 PDAC 中吉西他滨耐药涉及的关键途径，从而提供了潜在的治疗策略。
