The lichen compound protolichesterinic acid (PA) has an anti-proliferative effect against several cancer cell lines of different origin. This effect cannot be explained by the known inhibitory activity of PA against 5- and 12-lipoxygenases. The aim was therefore to search for mechanisms for the anti-proliferative activity of PA. Two cancer cell lines of different origin, both sensitive to anti-proliferative effects of PA, were selected for this study, T-47D from breast cancer and AsPC-1 from pancreatic cancer. Morphological changes were assessed by transmission electron microscopy, HPLC coupled with TOF spectrometry was used for metabolomics, mitochondrial function was measured using the Agilent Seahorse XFp Real-time ATP assay and glucose/lactate levels by radiometry. Levels of glutathione, NADP/NADPH and reactive oxygen species [ROS] were measured by luminescence. Following exposure to PA both cell lines showed structural changes in mitochondria that were in line with a measured reduction in oxidative phosphorylation and increased glycolysis. These changes were more marked in T-47D, which had poorer mitochondrial function at baseline. PA was processed and expelled from the cells via the mercapturic pathway, which consumes glutathione. Nevertheless, glutathione levels were increased after 24 hours of exposure to PA, implying enhanced synthesis. Redox balance was not much affected and ROS levels were not increased. We conclude that PA is metabolically processed and expelled from cells, leading indirectly to increased glutathione levels with minimal effects on redox balance. The most marked effect was on mitochondrial structure and metabolic function implying that effects of PA may depend on mitochondrial fitness.

中文翻译：

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抗增殖性地衣化合物原胆甾素酸抑制氧化磷酸化并通过癌细胞中的汞途径进行处理

地衣化合物protolichesterinic acid (PA) 对几种不同来源的癌细胞系具有抗增殖作用。这种效应不能用已知的 PA 对 5-和 12-脂氧合酶的抑制活性来解释。因此，目的是寻找 PA 的抗增殖活性机制。本研究选择了两种不同来源的癌细胞系，它们都对 PA 的抗增殖作用敏感，来自乳腺癌的 T-47D 和来自胰腺癌的 AsPC-1。通过透射电子显微镜评估形态变化，将 HPLC 与 TOF 光谱结合用于代谢组学，使用 Agilent Seahorse XFp 实时 ATP 测定法测量线粒体功能，并通过辐射测量法测量葡萄糖/乳酸水平。谷胱甘肽水平，通过发光测量NADP/NADPH和活性氧[ROS]。暴露于 PA 后，两种细胞系都显示出线粒体的结构变化，这与测量的氧化磷酸化减少和糖酵解增加一致。这些变化在 T-47D 中更为显着，其基线线粒体功能较差。PA通过消耗谷胱甘肽的巯基途径被处理并从细胞中排出。然而，暴露于 PA 24 小时后，谷胱甘肽水平增加，这意味着合成增强。氧化还原平衡没有受到太大影响，活性氧水平没有增加。我们得出结论，PA 被代谢处理并从细胞中排出，间接导致谷胱甘肽水平升高，而对氧化还原平衡的影响最小。