Investigation of ENO2 as a promising novel marker for the progression of colorectal cancer with microsatellite instability-high.

BACKGROUND: Microsatellite instability-high (MSI-H) has emerged as a significant biological characteristic of colorectal cancer (CRC). Studies reported that MSI-H CRC generally had a better prognosis than microsatellite stable (MSS)/microsatellite instability-low (MSI-L) CRC, but some MSI-H CRC patients exhibited distinctive molecular characteristics and experienced a less favorable prognosis. In this study, our objective was to explore the metabolic transcript-related subtypes of MSI-H CRC and identify a biomarker for predicting survival outcomes. METHODS: Single-cell RNA sequencing (scRNA-seq) data of MSI-H CRC patients were obtained from the Gene Expression Omnibus (GEO) database. By utilizing the copy number variation (CNV) score, a malignant cell subpopulation was identified at the single-cell level. The metabolic landscape of various cell types was examined using metabolic pathway gene sets. Subsequently, functional experiments were conducted to investigate the biological significance of the hub gene in MSI-H CRC. Finally, the predictive potential of the hub gene was assessed using a nomogram. RESULTS: This study revealed a malignant tumor cell subpopulation from the single-cell RNA sequencing (scRNA-seq) data. MSI-H CRC was clustered into two subtypes based on the expression profiles of metabolism-related genes, and ENO2 was identified as a hub gene. Functional experiments with ENO2 knockdown and overexpression demonstrated its role in promoting CRC cell migration, invasion, glycolysis, and epithelial-mesenchymal transition (EMT) in vitro. High expression of ENO2 in MSI-H CRC patients was associated with worse clinical outcomes, including increased tumor invasion depth (p = 0.007) and greater likelihood of perineural invasion (p = 0.015). Furthermore, the nomogram and calibration curves based on ENO2 showed potential prognosis predictive performance. CONCLUSION: Our findings suggest that ENO2 serves as a novel prognostic biomarker and is associated with the progression of MSI-H CRC.

Regulation of macrophage polarization and glucose metabolism by the ERK/MAPK-HK1 signaling pathway in paraquat-induced acute lung injury.

Acute lung injury is the leading cause of paraquat (PQ) poisoning-related mortality. The mechanism by which macrophages are involved in PQ-induced acute lung injury remains unclear. In recent years, the role of metabolic reprogramming in macrophage functional transformation has received significant attention. The current study aimed to identify the role of altered macrophage glucose metabolism and molecular mechanisms in PQ poisoning-induced acute lung injury. We established a model of acute lung injury in PQ-intoxicated mice via the intraperitoneal injection of PQ. PQ exposure induces macrophage M1 polarization and promotes the release of inflammatory factors, which causes the development of acute lung injury in mice. In vitro analysis revealed that PQ altered glucose metabolism, which could be reversed by siRNA transfection to silence the expression of HK1, a key enzyme in glucose metabolism. RNA sequencing revealed that the ERK/MAPK pathway was the crucial molecular mechanism of PQ pathogenesis. Further, U0126, an ERK inhibitor, could inhibit PQ-induced HK1 activation and macrophage M1 polarization. These findings provide novel insights into the previously unrecognized mechanism of ERK/MAPK-HK1 activation in PQ poisoning.

Lactate enhances NMNAT1 lactylation to sustain nuclear NAD+ salvage pathway and promote survival of pancreatic adenocarcinoma cells under glucose-deprived conditions.

The aim of this study was to investigate the underlying molecular mechanism behind the promotion of cell survival under conditions of glucose deprivation by l-lactate. To accomplish this, we performed tissue microarray and immunohistochemistry staining to analyze the correlation between the abundance of pan-Lysine lactylation and prognosis. In vivo evaluations of tumor growth were conducted using the KPC and nude mice xenograft tumor model. For mechanistic studies, multi-omics analysis, RNA interference, and site-directed mutagenesis techniques were utilized. Our findings robustly confirmed that l-lactate promotes cell survival under glucose deprivation conditions, primarily by relying on GLS1-mediated glutaminolysis to support mitochondrial respiration. Mechanistically, we discovered that l-lactate enhances the NMNAT1-mediated NAD+ salvage pathway while concurrently inactivating p-38 MAPK signaling and suppressing DDIT3 transcription. Notably, Pan-Kla abundance was significantly upregulated in patients with Pancreatic adenocarcinoma (PAAD) and associated with poor prognosis. We identified the 128th Lysine residue of NMNAT1 as a critical site for lactylation and revealed EP300 as a key lactyltransferase responsible for catalyzing lactylation. Importantly, we elucidated that lactylation of NMNAT1 enhances its nuclear localization and maintains enzymatic activity, thereby supporting the nuclear NAD+ salvage pathway and facilitating cancer growth. Finally, we demonstrated that the NMNAT1-dependent NAD+ salvage pathway promotes cell survival under glucose deprivation conditions and is reliant on the activity of Sirt1. Collectively, our study has unraveled a novel molecular mechanism by which l-lactate promotes cell survival under glucose deprivation conditions, presenting a promising strategy for targeting lactate and NAD+ metabolism in the treatment of PAAD.

Autophagy mediated FTH1 degradation activates gasdermin E dependent pyroptosis contributing to diquat induced kidney injury.

Acute kidney injury (AKI) induced by diquat (DQ) progresses rapidly, leading to high mortality, and there is no specific antidote for this chemical. Our limited knowledge of the pathogenic toxicological mechanisms of DQ has hindered the development of treatments against DQ poisoning. Pyroptosis is a form of programmed cell death and was recently identified as a novel molecular mechanism of drug-induced AKI. To explore the role of pyroptosis in HK-2 cells exposed to DQ, the plasma membrane damage of the cells was detected by LDH release assay. Western blot was performed to detect the cleavage of GSDME. Proteomics analysis was performed to explore the mechanism of DQ induced nephrotoxicity. FerroOrange probe was used to measure the intracellular Fe2+ levels. Herein, we show that DQ induces pyroptosis in HK-2 cells. Mechanistically, DQ induces the accumulation of mitochondrial ROS and initiates the cleavage of gasdermin E (GSDME) in an intrinsic mitochondrial pathway. Knockout of GSDME attenuated DQ-induced cell death. Further analysis revealed that loss of FTH1 induces Fe2+ accumulation, contributing to DQ-induced pyroptosis. Knockdown LC3B could help restore the expression of FTH1 and improve cell viability. Moreover, we found DFO, an iron chelator, could reduce cellular Fe2+ levels and inhibit pyroptosis. Collectively, these findings suggest an unrecognized mechanism for GSDME-dependent pyroptosis in DQ-induced AKI.