Cancer cells are frequently confronted with metabolic stress in tumor microenvironments due to their rapid growth and limited nutrient supply. Metabolic stress induces cell death through ROS-induced apoptosis. However, cancer cells can adapt to it by altering the metabolic pathways. AMPK and AKT are two primary effectors in response to metabolic stress: AMPK acts as an energy-sensing factor which rewires metabolism and maintains redox balance. AKT broadly promotes energy production in the nutrient abundance milieu, but the role of AKT under metabolic stress is in dispute. Recent studies show that AMPK and AKT display antagonistic roles under metabolic stress. Metabolic stress-induced ROS signaling lies in the hub between metabolic reprogramming and redox homeostasis. Here, we highlight the cross-talk between AMPK and AKT and their regulation on ROS production and elimination, which summarizes the mechanism of cancer cell adaptability under ROS stress and suggests potential options for cancer therapeutics.
BackgroundMetabolic plasticity has been increasingly thought to be a determinant of tumor growth and metastasis. MACC1, a transcriptional regulator of MET, was recognized as an oncogene in gastric cancer (GC); however, its transcriptional or post-translational regulation was not clear. We previously reported the metabolic role of MACC1 in glycolysis to promote GC progression. MACC1-AS1 is the antisense lncRNA of MACC1, yet its function was previously unknown.MethodsWe profiled and analyzed the expression of MACC1-AS1 utilizing the TCGA database as well as in situ hybridization using 123 pairs of GC tissues and matched adjacent normal gastric mucosa tissues (ANTs). The biological role of MACC1-AS1 in cell growth and metastasis was determined by performing in vitro and in vivo functional experiments. Glycolysis and antioxidant capabilities were assayed to examine its metabolic function. Further, the specific regulatory effect of MACC1-AS1 on MACC1 was explored transcriptionally and post-transcriptionally.ResultsMACC1-AS1 was shown to be expressed significantly higher in GC tissues than in ANTs, which predicted poor prognosis in GC patients. MACC1-AS1 promoted GC cell proliferation and inhibited cell apoptosis under metabolic stress. Mechanistically, MACC1-AS1 stabilized MACC1 mRNA and post-transcriptionally augmented MACC1 expression. Further, MACC1-AS1 was shown to mediate metabolic plasticity through MACC1 upregulation and subsequent enhanced glycolysis and anti-oxidative capabilities, and this was suggested to be coordinated by the AMPK/Lin28 pathway.ConclusionsElevated expression of MACC1-AS1 in gastric cancer tissues is linked to poor prognosis and promotes malignant phenotype upon cancer cells. MACC1-AS1 is elevated under metabolic stress and facilitates metabolic plasticity by promoting MACC1 expression through mRNA stabilization. Our study implicates lncRNA MACC1-AS1 as a valuable biomarker for GC diagnosis and prognosis.Electronic supplementary materialThe online version of this article (10.1186/s12943-018-0820-2) contains supplementary material, which is available to authorized users.
BACKGROUND: Ferroptosis is a recently discovered form of iron-dependent nonapoptotic cell death. It is characterized by loss of the activity of the lipid repair enzyme, glutathione peroxidase 4 (GPX4), and accumulation of lethal reactive lipid oxygen species. However, we still know relatively little about ferroptosis and its molecular mechanism in gastric cancer (GC) cells. Here, we demonstrate that erastin, a classic inducer of ferroptosis, induces this form of cell death in GC cells and that cysteine dioxygenase 1 (CDO1) plays an important role in this process. METHODS: We performed quantitative real-time polymerase chain reaction, Western blotting, cell viability assay, reactive oxygen species (ROS) assay, glutathione assay, lipid peroxidation assay, RNAi and gene transfection, immunofluorescent staining, dual-luciferase reporter assay, transmission electron microscopy, and chromatin immunoprecipitation assay to study the regulation of ferroptosis in GC cells. Mouse xenograft assay was used to figure out the mechanism in vivo. RESULTS: Silencing CDO1 inhibited erastin-induced ferroptosis in GC cells both in vitro and in vivo. Suppression of CDO1 restored cellular GSH levels, prevented ROS generation, and reduced malondialdehyde, one of the end products of lipid peroxidation. In addition, silencing COO1 maintained mitochondrial morphologic stability in erastin-treated cells. Mechanistically, c-Myb transcriptionally regulated CDO1, and inhibition of CDO1 expression upregulated GPX4 expression. CONCLUSIONS: Our findings give a better understanding of ferroptosis and its molecular mechanism in GC cells, gaining insight into ferroptosis-mediated cancer treatment.
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