Aims

Pyruvate carboxylase (PC) plays a key role in cancer cell metabolic reprogramming. Whether metabolic reprogramming and PC are related in PDAC is unclear. Here, the effect of PC expression on PDAC tumorigenesis and metabolic reprogramming were evaluated.

Materials and methods

PC protein expression in PDAC and precancerous tissues was measured through immunohistochemistry. The maximum standardized uptake (SUVmax) of ¹⁸F-fluoro-2-deoxy-2-d-glucose (¹⁸F-FDG) in PDAC patient PET/CT scans before surgical resection was retrospectively determined. Stable PC-knockdown and PC-overexpressing cells were established using lentiviruses, and PDAC progression was assessed in vivo and in vitro. Lactate content, ¹⁸F-FDG cell uptake rate, mitochondrial oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) were measured in cells. RNA sequencing revealed and qPCR verified differentially expressed genes (DEGs) after PC knockdown. The signaling pathways involved were determined by Western blotting.

Key findings

PC was significantly upregulated in PDAC tissues vs. precancerous tissues. A high SUVmax correlated with PC upregulation. PC knockdown significantly inhibited PDAC progression. Lactate content, SUVmax, and ECAR significantly decreased after PC knockdown. Peroxisome proliferator-activated receptor gamma coactivator-one alpha (PGC-1α) was upregulated after PC knockdown; and PGC1a expression promoted AMPK phosphorylation to activate mitochondrial metabolism. Metformin significantly inhibited mitochondrial respiration after PC knockdown, further activated AMPK and downstream carnitine palmitoyltransferase 1A (CPT1A)-regulated fatty acid oxidation (FAO), and inhibited PDAC cells progression.

Significance

PDAC cell uptake of FDG was positively correlated with PC expression. PC promotes PDAC glycolysis, and reducing PC expression can increase PGC1a expression, activate AMPK, and restore metformin sensitivity.

中文翻译：

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抑制丙酮酸羧化酶可通过激活 AMPK 逆转胰腺癌中的二甲双胍耐药性

目标

丙酮酸羧化酶（PC）在癌细胞代谢重编程中发挥着关键作用。PDAC 中代谢重编程和 PC 是否相关尚不清楚。在此，评估了 PC 表达对 PDAC 肿瘤发生和代谢重编程的影响。

材料和方法

通过免疫组织化学测定 PDAC 和癌前组织中 PC 蛋白的表达。回顾性确定手术切除前 PDAC 患者 PET/CT 扫描中¹⁸ F-氟-2-脱氧-2- d-葡萄糖 ( ¹⁸ F-FDG)的最大标准化摄取 (SUVmax) 。使用慢病毒建立稳定的 PC 敲低和 PC 过表达细胞，并在体内和体外评估 PDAC 进展。测定细胞中乳酸含量、^{~(18) F-FDG细胞摄取率、线粒体耗氧率(OCR)和细胞外酸化率(ECAR)。}RNA 测序揭示并 qPCR 验证了 PC 敲低后的差异表达基因 (DEG)。通过蛋白质印迹法确定所涉及的信号通路。

主要发现

与癌前组织相比，PDAC 组织中的 PC 显着上调。高 SUVmax 与 PC 上调相关。PC 敲除显着抑制 PDAC 进展。PC 敲除后，乳酸含量、SUVmax 和 ECAR 显着下降。PC 敲低后，过氧化物酶体增殖物激活受体 γ 共激活剂一 α (PGC-1α) 上调；PGC1a表达促进AMPK磷酸化，激活线粒体代谢。PC 敲低后，二甲双胍显着抑制线粒体呼吸，进一步激活 AMPK 和下游肉碱棕榈酰转移酶 1A (CPT1A) 调节的脂肪酸氧化 (FAO)，并抑制 PDAC 细胞进展。

意义

PDAC细胞对FDG的摄取与PC表达呈正相关。PC促进PDAC糖酵解，减少PC表达可增加PGC1a表达，激活AMPK，恢复二甲双胍敏感性。