Estaras Matias, Martinez Remigio, Garcia Alfredo, Ortiz-Placin Candido, Iovanna Juan L, Santofimia-Castaño Patricia, Gonzalez Antonio
Instituto de Biomarcadores de Patologías Moleculares, Departamento de Fisiología, Universidad de Extremadura, Cáceres, España.
Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, España.
Biochem Pharmacol. 2022 Aug;202:115118. doi: 10.1016/j.bcp.2022.115118. Epub 2022 Jun 4.
Pancreatic stellate cells (PSCs), the main cell type responsible for the development of fibrosis in pancreatic cancer, proliferate actively under hypoxia. Melatonin has received attention as a potential antifibrotic agent due to its anti-proliferative actions on PSCs. In this work, we investigated the activation of the PI3K/Akt/mTOR pathway and the metabolic adaptations that PSCs undergo under hypoxic conditions, as well as the probable modulation by melatonin. Incubation of cells under hypoxia induced an increase in cell proliferation, and in the expression of alpha-smooth muscle actin and of collagen type 1. In addition, an increase in the phosphorylation of Akt was observed, whereas a decrease in the phosphorylation of PTEN and GSK-3b was noted. The phosphorylation of mTOR and its substrate p70 S6K was decreased under hypoxia. Treatment of PSCs with melatonin under hypoxia diminished cell proliferation, the levels of alpha-smooth muscle actin and of collagen type 1, the phosphorylation of Akt and increased phosphorylation of mTOR. Mitochondrial activity decreased in PSCs under hypoxia. A glycolytic shift was observed. Melatonin further decreased mitochondrial activity. Under hypoxia, no increase in autophagic flux was noted. However, melatonin treatment induced autophagy activation. Nevertheless, inhibition of this process did not induce detectable changes in the viability of cells treated with melatonin. We conclude that PSCs undergo metabolic adaptation under hypoxia that might help them survive and that pharmacological concentrations of melatonin modulate cell responses to hypoxia. Our results contribute to the knowledge of the mechanisms by which melatonin could modulate fibrosis within the pancreas.
胰腺星状细胞（PSCs）是胰腺癌纤维化发展的主要细胞类型，在缺氧条件下会积极增殖。褪黑素因其对PSCs的抗增殖作用而作为一种潜在的抗纤维化剂受到关注。在这项研究中，我们研究了缺氧条件下PSCs中PI3K/Akt/mTOR信号通路的激活情况、代谢适应性变化，以及褪黑素可能的调节作用。在缺氧条件下培养细胞会导致细胞增殖增加，α-平滑肌肌动蛋白和Ⅰ型胶原蛋白的表达增加。此外，观察到Akt磷酸化增加，而PTEN和GSK-3b的磷酸化减少。缺氧条件下mTOR及其底物p70 S6K的磷酸化减少。在缺氧条件下用褪黑素处理PSCs可减少细胞增殖、α-平滑肌肌动蛋白和Ⅰ型胶原蛋白的水平、Akt的磷酸化，并增加mTOR的磷酸化水平。缺氧条件下PSCs的线粒体活性降低，观察到糖酵解转变。褪黑素进一步降低了线粒体活性。在缺氧条件下，自噬通量没有增加。然而，褪黑素处理可诱导自噬激活。尽管如此，抑制这一过程并未在褪黑素处理的细胞活力中诱导可检测到的变化。我们得出结论，PSCs在缺氧条件下会发生代谢适应性变化，这可能有助于它们存活，并且药理学浓度的褪黑素可调节细胞对缺氧的反应。我们的结果有助于了解褪黑素调节胰腺纤维化的机制。
