Development of a Risk Model and Genotyping Patterns Based on Disulfidptosis-Related lncRNAs to Predict Prognosis and Immune Landscape in Osteosarcoma.

BACKGROUND: Osteosarcoma (OS) is the most prevalent orthopedic malignancy with a dismal prognosis. Disulfidptosis-related lncRNAs (DRLncs) may be related to the progression of OS, but their potential molecular regulatory role is still unclear. METHODS: Based on the data collected from The Cancer Genome Atlas (TCGA), we conducted correlation analysis and the univariate Cox analysis to screen prognosis-related DRLncs, followed by developing genotyping patterns and corresponding classifier. Subsequently, the survival analysis, enrichment analysis, drug sensitivity analysis and immune infiltration analysis were performed. Afterward, multivariate Cox regression was used to construct a risk model, which was further validated by the receiver operating characteristic (ROC) curve. The aberrant expression of hub DRLncs in OS was validated using the Reverse Transcription Polymerase Chain Reaction (RT-qPCR) assay. RESULTS: We identified 262 DRLncs and eleven prognosis-related DRLncs through filtering. We then constructed two distinct expression patterns of prognosis-related DRLncs and developed a classifier. We obtained 393 differentially expressed genes (DEGs) between different subtypes, which were significantly enriched in biological processes related to the extracellular matrix, integrin binding, focal adhesion, and Wnt signaling pathways. Through immune infiltration analysis, the activated CD4 memory T cells, resting natural killer (NK) cells, M1 macrophages, and resting dendritic cells (DC) were observed to exhibit different abundance in distinct subtypes. In the drug sensitivity analysis, tamoxifen showed a promising effect for drug-resistant OS. Furthermore, we identified five hub DRLncs and constructed a risk model. The RT-qPCR confirmed the aberrant expression of five hub DRLncs in OS. CONCLUSIONS: The present study identified DRLncs in OS, and conducted a comprehensive investigation of DRLncs-related expression patterns, survival status, immune landscape and drug sensitivity to reveal the difference in prognostic, pharmacological and immunological phenotype characteristics between distinct subtypes. Additionally, we developed a risk model to predict the prognosis, and constructed a genotyping classifier to predict the above phenotype characteristics in OS.

α-LA attenuates microcystin-LR-induced hepatocellular oxidative stress in mice through Nrf2-mediated antioxidant and detoxifying enzymes.

Microcystins constitute a class of toxins synthesized by cyanobacteria and are known to inflict significant damage on the antioxidant defense system of living organisms, primarily targeting the liver. α-Lipoic acid (α-LA) is universally recognized as a potent antioxidant in biological systems. It exerts its beneficial effects through multiple mechanisms-directly neutralizing reactive oxygen species (ROS) and free radicals, and indirectly enhancing antioxidant defenses by facilitating the regeneration of glutathione (GSH). However, the precise modus operandi of α-LA's protective effect against Microcystin-LR-induced hepatotoxicity remains incompletely elucidated. The present study, therefore, employed α-LA to explore its protective role against Microcystin-LR exposure in mice. A model of Microcystin-LR-induced hepatic injury was established by administering Microcystin-LR into the peritoneal cavity of BALB/c mice daily over a two-week period. Thereafter, BALB/c mice were pre-treated with varying concentrations of α-LA via oral gavage for a duration of 7 days, followed by a 7-day exposure to Microcystin-LR. Our findings reveal that α-LA pre-treatment significantly mitigated hepatic pathologies in Microcystin-LR-exposed mice. Furthermore, α-LA administration led to a notable elevation in the activities and expression levels of nuclear factor erythroid 2-related factor 2, superoxide dismutase, glutathione peroxidase, glutathione S-transferase, and glutathione-indicative of its antioxidative capacity. Concurrently, a significant decrease was observed in the activities and expression levels of malondialdehyde and cytochrome P450 2E1. Consequently, α-LA emerges as a promising therapeutic candidate for the amelioration of liver oxidative damage subsequent to Microcystin-LR exposure.

Research on anti-hepatocellular carcinoma activity and mechanism of Polygala fallax Hemsl.

ETHNOPHARMACOLOGICAL RELEVANCE: Polygala fallax Hemsl. is a kind of traditional medicine of Yao Minority in China. In Chinese medicine practice, Polygala fallax Hemsl. is commonly prescribed to treat all kinds of acute and chronic hepatitis. AIM OF THE STUDY: The present study aimed at investigating the effects and its possible mechanism of Polygala fallax Hemsl. on the proliferation and apoptosis of HepG2 cells (a kind of human hepatoma cell). MATERIALS AND METHODS: Through a variety of experimental methods, including MTT technique and Hoechst staining to detect apoptosis in Hepatocyte HepG2 cells, flow cytometry to observe the pro-apoptotic and circulatory arrest effects as well as real-time fluorescence quantitative polymerase chain reaction (q-PCR) technique to examine the expression levels of Bcl-2/Bax gene and prote Western blot to examine the expression levels of bcl-2/bax,caspase3,8,9,CyclinA,p21,p27,ERK.Phospho-ERK and AKT, Phospho-AKT in HepG2 cells. RESULTS: The results showed that compared with the control group, all polarity fractions of P. fallax had inhibitory effects on HepG2 cells, among which the inhibition effect of ethyl acetate fraction in 0.036 ± 0.001 mg/mL of IC50 for 24 h was the most obvious (P < 0.01). And the HepG2 cells induced at the ethyl acetate fraction could up-regulate Bax gene and protein, while down-regulating Bcl-2 gene and protein (P < 0.05) during S phase in a dose-dependent manner. In addition, the ethyl acetate site of Larch can also down regulate the expression of ERK, AKT and activate caspase 3, 8 and 9. CONCLUSION: It could be concluded that the ethyl acetate fraction of Polygala fallax Hemsl. can significantly prohibit the proliferation of HepG2 cells. The possible mechanism is to promote the expression of Bax, inhibit the expression of Bcl-2, and down regulate the expression of AKT and ERK.

Linc1557 is critical for the initiation of embryonic stem cell differentiation by directly targeting the LIF/STAT3 signaling pathway.

Embryonic stem cells (ESCs) have self-renewal and multi-lineage differentiation potential and perform critical functions in development and biomedicine. Several long noncoding RNAs (lncRNAs) have been reported as key regulators of stem cell pluripotency and differentiation. However, the function and regulatory mechanism of lncRNAs during the initiation of ESC differentiation remains unclear. Here, we found that linc1557 was highly expressed in mouse ESCs and required for the initiation of ESC differentiation. Knockdown of linc1557 increased the expression and phosphorylation levels of signal transducer and activator of transcription 3 (STAT3), a key factor in the leukemia inhibitory factor (LIF)/STAT3 signaling pathway. Furthermore, we found that linc1557 directly bound to Stat3 mRNA and affected its stability. The differentially expressed transcriptome after linc1557 knockdown in ESCs was involved primarily in multicellular organism development and cell differentiation as similar to that after Stat3 knockdown. Moreover, either knockdown of Stat3 or addition of a LIF/STAT3 signaling inhibitor rescued the suppressive effects of linc1557 knockdown on the initiation of mouse ESC differentiation. These findings not only elucidated the critical function of linc1557 in the initiation of mouse ESC differentiation but also clarified that its specific mechanism as directly affecting Stat3 mRNA stability, which enhanced the understanding of the lncRNA-mediated regulatory mechanism for mRNA stability and key signaling pathways in ESC pluripotency and differentiation.

N6-Methyladenosine modification of lincRNA 1281 is critically required for mESC differentiation potential.

Previous studies have revealed the critical roles of N6-methyladenosine (m6A) modification of mRNA in embryonic stem cells (ESCs), but the biological function of m6A in large intergenic noncoding RNA (lincRNA) is unknown. Here, we showed that the internal m6A modification of linc1281 mediates a competing endogenous RNA (ceRNA) model to regulate mouse ESC (mESC) differentiation. We demonstrated that loss of linc1281 compromises mESC differentiation and that m6A is highly enriched within linc1281 transcripts. Linc1281 with RRACU m6A sequence motifs, but not an m6A-deficient mutant, restored the phenotype in linc1281-depleted mESCs. Mechanistic analyses revealed that linc1281 ensures mESC identity by sequestering pluripotency-related let-7 family microRNAs (miRNAs), and this RNA-RNA interaction is m6A dependent. Collectively, these findings elucidated the functional roles of linc1281 and its m6A modification in mESCs and identified a novel RNA regulatory mechanism, providing a basis for further exploration of broad RNA epigenetic regulatory patterns.

Synergetic effects of DNA methylation and histone modification during mouse induced pluripotent stem cell generation.

DNA methylation and histone methylation (H3K27me3) have been reported as major barriers to induced pluripotent stem cell (iPSC) generation using four core transcription factors (Oct4, Sox2, Klf4, and c-Myc, termed OSKM). Here, to illustrate the possibility of deriving iPSCs via demethylation, as well as the exact effects of DNA methylation and histone modification on gene expression regulation, we performed RNA sequencing to characterize the transcriptomes of ES cells and iPSCs derived by demethylation with miR-29b or shDnmt3a, and carried out integrated analyses. Results showed that OSKM + miR-29b-iPSC was more close to ES cells than the others, and up-regulated genes typically presented with methylated CpG-dense promoters and H3K27me3-enriched regions. The differentially expressed genes caused by introduction of DNA demethylation during somatic cell reprogramming mainly focus on stem cell associated GO terms and KEGG signaling pathways, which may decrease the tumorigenesis risk of iPSCs. These findings indicated that DNA methylation and histone methylation have synergetic effects on regulating gene expression during iPSC generation, and demethylation by miR-29b is better than shDnmt3a for iPSC quality. Furthermore, integrated analyses are superior for exploration of slight differences as missed by individual analysis.