Biology subjects

Chaves-Filho, A. B.

Publications and source records attributed to Chaves-Filho, A. B..

6 recordsLinked to original sources

bioRxiv2026

Catabolism of extracellular glutathione is a driver of metastasis formation

Metastasizing cancer cells require metabolic plasticity to adapt to the microenvironment of the target organ. Analyzing metabolites in interstitial fluids, we found that the liver microenvironment is devoid of cystine but contains high concentrations of glutathione (GSH). Detailed mechanistic analysis revealed that cancer cells degrade extracellular GSH utilizing gamma-glutamyl-transferase (GGT) activity for provision of cysteine to support proliferation and prevent ferroptosis under cystine-free conditions. This was independent of system Xc- but required activity of glutamate-cysteine ligase (GCLC). GGT1 expression was associated with poor survival and upregulated in liver metastases of human breast cancer patients. Overexpression of Ggt1 in murine breast cancer cells enhanced their capacity for liver colonization and promoted lung metastases after orthotopic implantation. This identifies extracellular GSH catabolism as driver of metastasis that supports proliferation and oxidative stress resistance in metabolically challenging microenvironments.

cancer biology↗

bioRxiv2026

Constitutive PI3K-AKT activation promotes steatohepatitis through de novo lipogenesis despite enhanced mitochondrial β-oxidation, essential fatty acid depletion and reduced lipid peroxidation

Background. Activation of de novo lipogenesis (DNL) is a major hallmark of steatotic liver disease (SLD), a highly prevalent group of diseases ranging from a harmless steatosis to more severe steatohepatitis, cirrhosis, and hepatocellular carcinoma. We interrogated herein the early alterations in liver proteome, transcriptome, lipidome, inflammation, fibrosis, and oxidative status in a mouse model of progressive SLD induced by constitutive activation of PI3K-AKT signaling, the major inducer of DNL. Methods. Male, 8 weeks-old mice bearing phosphatase and tensin homolog (Pten) deletion and therefore constitutive activation of PI3K-AKT in hepatocytes (albumin-Cre) and littermate controls were evaluated for liver steatosis, injury, lipid peroxidation, metabolism, proteome, lipidome and transcriptome either upon feeding with a chow or high-fat diets supplemented or not with linoleic acid or after treatment with vehicle or acetyl-CoA carboxylase (ACC) inhibitor (ND-630, 20 mg/kg/day, i.p.) Results. Mice bearing Pten deletion and therefore constitutive activation of PI3K-AKT in hepatocytes display steatohepatitis characterized by enhanced DNL, severe steatosis, hepatocyte ballooning, inflammation, fibrosis and hepatomegaly, which, unexpectedly, was associated with reduced lipid peroxidation, increased GSH content and enhanced rates of triacylglycerol turnover, fatty acid {beta}-oxidation, tricarboxylic acid cycle flux, and mitochondrial respiration, altogether promoting a robust lipidome remodeling mainly defined by enrichment of DNL-derived fatty acids in detriment of a broad depletion of essential fatty acids (linoleic and -linolenic acids) and cardiolipins. Dietary restoration of liver linoleic acid content mildly attenuated liver inflammation, without however affecting lipid peroxidation and improving steatosis and fibrosis, whereas pharmacological acetyl-CoA carboxylase (ACC) and DNL inhibition markedly reduced steatosis, inflammation and fibrosis, despite further lowering hepatic linoleic acid content. Conclusions. Collectively, these findings support a harmful role of essential fatty acids depletion fomenting liver inflammation and identify DNL as a major culprit of steatohepatitis induced by constitutive PI3K-AKT activation.

biochemistry↗

bioRxiv2026

Severely lipoatrophic mice are hypermetabolic and hyperthermic under thermoneutral conditions in part due to an enhanced liver de novo lipogenesis

White, beige and brown adipocytes store energy as lipids, secrete hormones and produce heat, playing an important role in the regulation of energy balance through not completely defined mechanisms. We investigate herein the impact of the almost complete absence of mature adipocytes (severe lipoatrophy) in the determination of energy balance (energy intake and expenditure) and homeothermy in mice. For this, mice with severe lipoatrophy induced by adipocyte deletion of peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) (PPAR{gamma} flox adiponectin-Cre) and littermate controls (PPAR{gamma} flox) were evaluated for energy balance, thermoneutral zone, core body temperature, locomotor activity, and gene expression profiles at different ambient temperatures. Severely lipoatrophic mice are heavier, hypermetabolic and hyperphagic and feature a widened thermoneutral zone, lower ambulatory activity, and metabolic inflexibility at both 23 and 17{degrees}C, along with unstable thermal behavior characterized by hyperthermia at 30{degrees}C, normothermia at 23{degrees}C, and bouts of hypothermia at 17{degrees}C. Noteworthy, lipoatrophic mice hypermetabolism at 30{degrees}C is not due to thyroid hormones, impaired insulation or increased body and lean masses and is not altered by pharmacological blockade of either {beta}-adrenergic receptor signaling with propranolol or skeletal muscle sarcoplasmic/endoplasmic reticulum Ca2+-ATPases (SERCA) and sarcolipin (SLN)-mediated calcium cycling with dantrolene, but is partially attenuated by pharmacological inhibition of acetyl-CoA carboxylase (ACC) and de novo lipogenesis with ND-630. In conclusion, severe lipoatrophy causes hypermetabolism and hyperthermia at 30{degrees}C partly through the activation of liver de novo fatty acid synthesis.

physiology↗

bioRxiv2025

Oxysterol Alterations in SOD1G93A ALS Rats: 25-Hydroxycholesterol and LPS-Binding Protein in Disease Progression

BackgroundDisruptions in cholesterol and oxysterol metabolism, along with neuroinflammation, are linked to amyotrophic lateral sclerosis (ALS), though the underlying mechanisms remain unclear. Given evidence of increased intestinal permeability in ALS, we investigated its link to neuroinflammation and oxysterol alterations in SOD1G93A rats. MethodsOxysterols were quantified in plasma and spinal cord from presymptomatic and symptomatic SOD1G93A rats and age-matched controls via ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry. Circulating LBP, a marker of intestinal permeability, was quantified via ELISA. ResultsOxysterols involved in bile acid biosynthesis - 7-hydroxycholesterol, 27-hydroxycholesterol (27-OH), and 3{beta}-hydroxycholestenoic acid - were increased in the plasma of symptomatic rats. The neuronal oxysterol 24(S)-hydroxycholesterol (24(S)-OH) decreased in the spinal cord but increased in the plasma. In contrast, 27-OH and 25-hydroxycholesterol (25-OH) levels were elevated in both plasma and spinal cord, with 25-OH rising during the presymptomatic stage. Presymptomatic animals also exhibited elevated LBP levels, which strongly correlated with spinal cord 25-OH levels, suggesting a link between systemic inflammation and neuroinflammation in ALS. ConclusionOxysterol alterations in plasma and spinal cord suggest compromised blood-spinal cord barrier integrity and early neuroinflammation. Elevated LBP levels indicate increased intestinal permeability and circulating LPS as contributors to neuroinflammation and neurodegeneration. These findings highlight 25-OH and LBP as markers and mediators of gut-brain axis interactions in ALS pathogenesis, particularly in the presymptomatic phase.

neuroscience↗

bioRxiv2024

Comparative study of Ergosterol and 7-dehydrocholesterol and their Endoperoxides: Generation, Identification and Impact in Phospholipid Membranes and Melanoma Cells

Melanoma is an aggressive cancer that has attracted attention in recent years due to its high mortality rate of 80%. Damage caused by oxidative stress generated by radical (type I reaction) and singlet oxygen, 1O2 (type II reaction) oxidative reactions may induce cancer. Thus, studies that aim to unveil the mechanism that drives these oxidative damage processes become relevant. Ergosterol, an analogue of 7-dehydrocholesterol, important in the structure of cell membranes, is widely explored in cancer treatment. However, to date little is known about the impact of different oxidative reactions on these sterols in melanoma treatment, and conflicting results about their effectiveness complicates the understanding of their role in oxidative damage. Our results highlight differences among ergosterol, 7-dehydrocholesterol (7-DHC) and cholesterol in membrane properties when subjected to distinct oxidative reactions. Furthermore, we conducted a comparative study exploring the mechanisms of cell damage by photodynamic treatment in A375 melanoma. Notably, endoperoxides from ergosterol and 7-DHC generated by 1O2 showed superior efficacy in reducing the viability of A375 cells compared to their precursor molecules. We also describe a step-by-step process to produce and identify endoperoxides derived from ergosterol and 7-DHC. While further studies are needed, this work provides new insights for understanding cancer cell death induced by different oxidative reactions in the presence of biologically relevant sterols.

biochemistry↗

bioRxiv2023

Plasma Oxylipin Profiling by High Resolution Mass Spectrometry Reveal Signatures of Inflammation and Hypermetabolism in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized not only by progressive loss of motor neurons, but also linked to systemic hypermetabolism, oxidative stress, and inflammation. In this context, oxylipins have been investigated as signaling molecules linked to neurodegeneration. However, the nature and role of major oxylipins involved in ALS disease progression remain unclear. Importantly, most methods focused on oxylipin analysis are based on low resolution mass spectrometry (LRMS), which usually confers high sensitivity, but not great accuracy for lipid identification, as provided by high-resolution MS (HRMS). Here, we established an ultra-high performance liquid chromatography coupled HRMS (LC-HRMS) method for simultaneous analysis of 126 oxylipins in plasma, including lipid hydroxides, ketones, epoxides, prostaglandins, leukotrienes, and others in a 15-minute run. Intra- and inter-day method validation showed high sensitivity (0.3 - 25 pg), accuracy and precision for more than 90 % of quality controls. This method was applied for the analysis of oxylipins in plasma of ALS rats overexpressing the mutant human Cu/Zn-superoxide dismutase gene (SOD1-G93A) at asymptomatic (ALS 70 days old) and symptomatic stages (ALS 120 days old), and their respective age-matched wild type controls (WT 70 days old and WT 120 days old). From the 56 oxylipins identified in plasma, 17 species were significantly altered. Remarkably, most of oxylipins linked to inflammation and oxidative stress derived from arachidonic acid, such as, prostaglandins, lipoxins, mono-hydroxides, and isoprostane, were increased in ALS 120d rats. In contrast, the linoleic acid diols involved in fatty acid uptake and {beta}-oxidation, 9(10)-DiHOME and 12(13)-DiHOME, were strongly decreased in the ALS 120d. In summary, we developed and validated a high-throughput LC-HRMS method for oxylipin analysis and provided a comprehensive overview of plasma oxylipins involved in ALS disease progression. Noteworthy, the oxylipins altered in plasma of ALS 120d rats have potential to be investigated and used as biomarkers for inflammation and hypermetabolism in ALS. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=136 SRC="FIGDIR/small/547101v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@937099org.highwire.dtl.DTLVardef@1c5847forg.highwire.dtl.DTLVardef@7dd09borg.highwire.dtl.DTLVardef@a9f8d_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗