Mitochondrial energy metabolism-related gene signature as a prognostic indicator for pancreatic adenocarcinoma.

Background: Pancreatic adenocarcinoma (PAAD) is a highly malignant gastrointestinal tumor and is associated with an unfavorable prognosis worldwide. Considering the effect of mitochondrial metabolism on the prognosis of pancreatic cancer has rarely been investigated, we aimed to establish prognostic gene markers associated with mitochondrial energy metabolism for the prediction of survival probability in patients with PAAD. Methods: Gene expression data were obtained from The Cancer Genome Atlas and Gene Expression Omnibus databases, and the mitochondrial energy metabolism-related genes were obtained from the GeneCards database. Based on mitochondrial energy metabolism score (MMs), differentially expressed MMRGs were established for MMs-high and MMs-low groups using ssGSEA. After the univariate Cox and least absolute and selection operator (LASSO) analyses, a prognostic MMRG signature was used in the multivariate Cox proportional regression model. Survival and immune cell infiltration analyses were performed. In addition, a nomogram based on the risk model was used to predict the survival probability of patients with PAAD. Finally, the expression of key genes was verified using quantitative polymerase chain reaction and immunohistochemical staining. Intro cell experiments were performed to evaluated the proliferation and invasion of pancreatic cancer cells. Results: A prognostic signature was constructed consisting of two mitochondrial energy metabolism-related genes (MMP11, COL10A1). Calibration and receiver operating characteristic (ROC) curves verified the good predictability performance of the risk model for the survival rate of patients with PAAD. Finally, immune-related analysis explained the differences in immune status between the two subgroups based on the risk model. The high-risk score group showed higher estimate, immune, and stromal scores, expression of eight checkpoint genes, and infiltration of M0 macrophages, which might indicate a beneficial response to immunotherapy. The qPCR results confirmed high expression of MMP11 in pancreatic cancer cell lines, and IHC also verified high expression of MMP11 in clinical pancreatic ductal adenocarcinoma tissues. In vitro cell experiments also demonstrated the role of MMP11 in cell proliferation and invasion. Conclusion: Our study provides a novel two-prognostic gene signature-based on MMRGs-that accurately predicted the survival of patients with PAAD and could be used for mitochondrial energy metabolism-related therapies in the future.

LINC00922 decoys SIRT3 to facilitate the metastasis of colorectal cancer through up-regulation the H3K27 crotonylation of ETS1 promoter.

BACKGROUND: Lysine crotonylation (Kcr) is up-regulation in colorectal cancer (CRC) tissues, while its specific contribution remains uncertain. This study aimed to elucidate the role and mechanism of crotonylation on Lys27 of histone H3 (H3K27cr) in facilitating CRC metastasis. METHODS: Immunohistochemistry was employed to investigate the correlation between H3K27cr and CRC metastasis. Both in vitro and in vivo assays employing loss function or gain function approaches were conducted to elucidate the role of LINC00922 in promoting CRC metastasis. ScRNA-seq analysis and immunoprecipitation analyses were employed to explore the underlying mechanism by which LINC00922 facilitates CRC metastasis through H3K27cr. RESULTS: Clinically, H3K27cr was upregulated in metastatic CRC tissues and positively correlated with advanced clinical stages. Functionally, knockdown of LINC00922 inhibited migration of CRC cells both in vitro and in vivo. Furthermore, the supplementation of NaCr restored the migration and invasion levels of LINC00922 stable knockdown cells by restoring the H3K27cr level. Mechanistically, LINC00922 promoted invasion and migration through H3K27cr mediated cell adhesion molecules (CAMs) in epithelial cells. Notably, LINC00922 interacted with the protein sirtuin 3 (SIRT3) and obstructed its binding to the promoter region of ETS1, leading to an elevation in the level of H3K27cr in this promoter region and the subsequent activation of ETS1 transcription. CONCLUSIONS: Our findings uncovered a novel regulatory function of H3K27cr, regulated by LINC00922, in facilitating CRC metastasis. This discovery contributed to a deeper comprehension of the involvement of histone crotonylation in the metastatic process of CRC.

Reduction of H3K27cr Modification During DNA Damage in Colon Cancer.

DNA damage plays an essential role in the initiation and development of colon cancer. Histone crotonylation is a newly discovered post-translational modification that is thought to promote gene expression. Whether histone crotonylation plays a role in DNA damage of cancer remains unknown, as does the putative underlying molecular mechanism. This study aimed to investigate the relationship between histone crotonylation and DNA damage of colon cancer using multiple bioinformatics analysis and western blotting. We discovered that genes with promoter occupied by histone crotonylation were associated with the activity of DNA damage in colon cancer patients. Additionally, we uncovered that the level of crotonylation on Lys27 of histone H3 (H3K27cr) decreased during camptothecin and etoposide treatment. Interestingly, sirtuin 6 was found to regulate the cellular level of H3K27cr. Taking these data together, our study provided a new perspective about histone crotonylation and DNA damage in colon cancer.

A Class of Protein-Coding RNAs Binds to Polycomb Repressive Complex 2 and Alters Histone Methylation.

Polycomb repressive complex 2 (PRC2) is a multi-subunit protein complex mediating the methylation of lysine 27 on histone H3 and playing an important role in transcriptional repression during tumorigenesis and development. Previous studies revealed that both protein-coding and non-coding RNAs could bind to PRC2 complex. However, the functions of protein-coding RNAs that bind to PRC2 complex in tumor are still unknown. Through data mining and RNA immunoprecipitation (RIP) assay, our study found that there were a class of protein-coding RNAs bound to PRC2 complex and H3 with tri-methylation on lysine 27. The Bayesian gene regulatory network analysis pointed out that these RNAs regulated the expression of PRC2-regulated genes in cancer. In addition, gene set enrichment analysis (GSEA), gene ontology (GO) analysis, and weighted gene co-expression network analysis (WGCNA) also confirmed that these RNAs were associated with histone modification in cancer. We also confirmed that MYO1C, a PRC2-bound transcript, inhibited the modification level of H3K27me3. Further detailed study showed that TMEM117 regulated TSLP expression through EZH2-mediated H3K27me3 modification. Interestingly, the RNA recognition motif of PRC2 complex might help these RNAs bind to the PRC2 complex more easily. The same regulatory pattern was found in mice as well.

Amphiregulin promotes hair regeneration of skin-derived precursors via the PI3K and MAPK pathways.

OBJECTIVES: There are significant clinical challenges associated with alopecia treatment, including poor efficiency of related drugs and insufficient hair follicles (HFs) for transplantation. Skin-derived precursors (SKPs) exhibit great potential as stem cell-based therapies for hair regeneration; however, the proliferation and hair-inducing capacity of SKPs gradually decrease during culturing. MATERIALS AND METHODS: We describe a 3D co-culture system accompanied by kyoto encyclopaedia of genes and genomes and gene ontology enrichment analyses to determine the key factors and pathways that enhance SKP stemness and verified using alkaline phosphatase assays, Ki-67 staining, HF reconstitution, Western blot and immunofluorescence staining. The upregulated genes were confirmed utilizing corresponding recombinant protein or small-interfering RNA silencing in vitro, as well as the evaluation of telogen-to-anagen transition and HF reconstitution in vivo. RESULTS: The 3D co-culture system revealed that epidermal stem cells and adipose-derived stem cells enhanced SKP proliferation and HF regeneration capacity by amphiregulin (AREG), with the promoted stemness allowing SKPs to gain an earlier telogen-to-anagen transition and high-efficiency HF reconstitution. By contrast, inhibitors of the phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways downstream of AREG signalling resulted in diametrically opposite activities. CONCLUSIONS: By exploiting a 3D co-culture model, we determined that AREG promoted SKP stemness by enhancing both proliferation and hair-inducing capacity through the PI3K and MAPK pathways. These findings suggest AREG therapy as a potentially promising approach for treating alopecia.

Downregulation of lncRNA EPB41L4A-AS1 Mediates Activation of MYD88-Dependent NF-κB Pathway in Diabetes-Related Inflammation.

PURPOSE: Long non-coding RNAs (lncRNAs) have been shown to be involved in many human diseases. In this study, we aimed to reveal the role and molecular mechanism of lncRNA EPB41L4A-AS1 in type 2 diabetic mellitus (T2DM)-related inflammation. METHODS: To explore the relationships between the expression of EPB41L4A-AS1 and inflammatory factors in the blood of T2DM patients, we analyzed peripheral blood mononuclear cell (PBMC) expression microarrays of T2DM patients and expression microarrays of PBMC treated with lipopolysaccharide (LPS) from the GEO database. The relationship between EPB41L4A-AS1 and phospho-p65 was explored by Western blotting (WB) and immunofluorescence. The interactions between EPB41L4A-AS1 and myeloid differentiation factor 88 (MYD88) were also verified through quantitative real-time PCR, WB, and chromatin immunoprecipitation. Glycolysis and mitochondrial stress were detected by Seahorse. RESULTS: EPB41L4A-AS1 showed very low expression, which was significantly negatively correlated with levels of inflammatory factors in PBMCs of T2DM patients and PBMCs treated with LPS. These results were verified by cell experiments on PBMC and THP-1 cells. Knockdown of EPB41L4A-AS1 led to the phosphorylation and nuclear translocation of p65 and thus activated the NF-κB signaling pathway; it also reduced the enrichment of H3K9me3 in the MYD88 promoter and increased expression of MYD88. Overall, EPB41L4A-AS1 knockdown promoted the level of glycolysis and ultimately enhanced the inflammatory response. CONCLUSION: EPB41L4A-AS1 knockdown activated the NF-κB signaling pathway through a MYD88-dependent regulatory mechanism, promoted glycolysis, and ultimately enhanced the inflammatory response. These results demonstrate that EPB41L4A-AS1 is closely associated with inflammation in T2DM, and that low expression of EPB41L4A-AS1 may be used as an indicator of chronic inflammation and possible diabetic vascular complications in T2DM patients.

Canagliflozin inhibits p-gp function and early autophagy and improves the sensitivity to the antitumor effect of doxorubicin.

Cancer easily induces resistance to most chemotherapy drugs. In this study, we investigated the combination cytotoxic and antitumor effects of canagliflozin (CAN) and doxorubicin (DOX) in vitro and in vivo. CAN significantly increased the cytotoxicity of DOX in HepG2, HepG2-ADR (adriamycin or doxorubicin-resistant) and MCF7 cells. CAN significantly promoted the intracellular uptake of DOX in HepG2 cells. CAN also reduced the P-glycoprotein (P-gp) level in HepG2 cells. The function of P-gp required ATP, but CAN significantly reduced the intracellular ATP level. CAN might inhibit the function of p-gp, increase the intracellular DOX concentration and contribute to an enhanced cytotoxic activity. Autophagy plays a protective role in chemotherapy-induced cell survival. However, CAN significantly inhibited DOX-induced autophagy in HepG2 cells, and the mechanism appeared to be mediated by promoting ULK1 ser 757 phosphorylation. The downregulation of P-gp may be associated with protein degradation but is independent of the autophagy pathway. Furthermore, in HepG2-xenograft BALB/c nude mice, CAN significantly increased the antitumor effect of DOX. This study is the first to report that a classical antidiabetic drug, CAN improved the sensitivity to the antitumor effect of DOX, and the potential molecular mechanisms of CAN may involve the inhibition of P-gp function and the autophagy pathway.

Overexpression of lncRNA EPB41L4A-AS1 Induces Metabolic Reprogramming in Trophoblast Cells and Placenta Tissue of Miscarriage.

Long non-coding RNAs (lncRNAs) have been shown to be crucial regulators in numerous human diseases. However, little is known about their effects on early recurrent miscarriage (RM). Here we aimed to investigate the role of lncRNA EPB41L4A-AS1 on placental trophoblast cell metabolic reprogramming, which might be involved in the pathogenesis of RM. After microarray and GEO database analyses, we found that EPB41L4A-AS1 was significantly increased in early RM placental tissue, and this increase may relate to estradiol-mediated upregulation of PGC-1α. EPB41L4A-AS1 overexpression inhibits glycolysis but increases the dependence on fatty acid oxidation in mitochondrion metabolism and suppresses the Warburg effect, which is necessary for rapid growth of the placental villus, leading to miscarriage. Mechanistic analyses demonstrated that EPB41L4A-AS1 functions as a lncRNA in the regulation of VDAC1 and HIF-1α expression through enhancement of H3K4me3 levels in the promoters of VDAC1 and HIF1A-AS1, a natural antisense transcript (NAT) lncRNA of HIF-1α. Taken together, these findings demonstrate that aberrant expression of EPB41L4A-AS1 is involved in the etiology of early RM, and it may be a candidate diagnostic hallmark and a potential therapeutic target for early RM treatment.

LncRNA EPB41L4A-AS1 regulates glycolysis and glutaminolysis by mediating nucleolar translocation of HDAC2.

BACKGROUND: LncRNAs have been found to be involved in various aspects of biological processes. In this study, we aimed to uncover the molecular mechanisms of lncRNA EPB41L4A-AS1 in regulating glycolysis and glutaminolysis in cancer cells. METHODS: The expression of EPB41L4A-AS1 in cancer patients was analyzed in TCGA and GEO datasets. The level of cellular metabolism was determined by extracellular flux analyzer. The relationship between p53 and EPB41L4A-AS1 was explored by qRT-PCR, luciferase assay and ChIP assay. The interactions between EPB41L4A-AS1 and HDAC2 or NPM1 were determined by RNA immunoprecipitation, RNA pull-down assay and RNA-FISH- immunofluorescence. FINDINGS: EPB41L4A-AS1 was a p53-regulated gene. Low expression and deletion of lncRNA EPB41L4A-AS1 were found in a variety of human cancers and associated with poor prognosis of cancer patients. Knock down EPB41L4A-AS1 expression triggered Warburg effect, demonstrated as increased aerobic glycolysis and glutaminolysis. EPB41L4A-AS1 interacted and colocalized with HDAC2 and NPM1 in nucleolus. Silencing EPB41L4A-AS1 reduced the interaction between HDAC2 and NPM1, released HDAC2 from nucleolus and increased its distribution in nucleoplasm, enhanced HDAC2 occupation on VHL and VDAC1 promoter regions, and finally accelerated glycolysis and glutaminolysis. Depletion of EPB41L4A-AS1 increased the sensitivity of tumor to glutaminase inhibitor in tumor therapy. INTERPRETATION: EPB41L4A-AS1 functions as a repressor of the Warburg effect and plays important roles in metabolic reprogramming of cancer.

A group of long noncoding RNAs identified by data mining can predict the prognosis of lung adenocarcinoma.

Long noncoding RNAs (lncRNA) are reported to be potential cancer biomarkers. This study aims to find new lncRNA biomarker relevant to lung adenocarcinoma. Gene expression profile and clinical data of lung adenocarcinoma and lung squamous cell carcinoma patients were downloaded from the UCSC Xena database. These data were analyzed to identify potential lncRNA prognostic biomarkers, and the candidate lncRNAs were analyzed and verified with association analysis, meta-analysis, survival analysis, gene ontology analysis, gene set enrichment analysis, and other statistical methods. A group of 5 lncRNAs was identified from the 1965 differentially expressed (fold-change >2) genes. Four of these 5 lncRNAs were expressed at a lower level in lung adenocarcinoma tissues and the other one at a higher level (P < .0001). A risk score model was constructed using a linear combination of the expression levels of these lncRNAs. High-risk patients showed poorer overall survival (hazard ratio [HR] = 2.14; 95% confidence interval [CI], 1.67-3.06, P < .0001), disease-free survival (HR = 1.84; 95% CI, 1.26-2.35, P = .0007), and recurrence-free survival (HR = 1.51; 95% CI, 1.02-2.40, P = .04). The 5-fold cross-validation and subsequent meta-analysis further verified that patients in the low-risk group had better survival (95% CI, 0.74-1.79, Z = 4.72, P < .00001). Furthermore, both univariate and multivariate Cox regression analyses revealed that the prognostic value of these 5 lncRNAs was independent of other clinical prognostic factors. Further analysis indicated that these 5 lncRNAs might be associated with tumor metastasis. Taken together, our study suggests new prognostic lncRNA biomarkers for lung adenocarcinoma.

Modeling endophilin-mediated Aß disposal in glioma cells.

Autophagy dysregulation has emerged in age-related neurological diseases (Ulland et al.; Matheoud et al.; Ashkenazi et al.). Alzheimer Disease (AD), the most common progressive neurodegenerative disorder, is characterized by the accumulation of amyloid-ß (Aß) plaques caused by aberrant Aß metabolism (Qiang et al.; Sevigny et al.; Ittner et al.). Glia constitute the brain immune system and ingest extracellular Aß for degradation via the autophagy-lysosome machinery (Ries and Sastre; Cho et al.). Here, we model the molecular rationale for this clearance process in glioma cells by showing that miR34a inhibits autophagy-mediated disposal of Aß fibrils and identifying two novel direct targets of miR34a, endophilin-3 and cathepsin B (CTSB, a previously reported enzyme for Aß degrading (Sun et al.)). Bioinformatics analyses revealed that endophilin-3 expresses at a significantly lower level in neurodegenerative diseases. Its gain-of-function substantially promotes both uptake and degradation of Aß while small interfering RNA (siRNA)-mediated endophilin-3 knockdown slowed down Aß clearance and blocked autolysosome formation. Mechanistically, gene ontology (GO) analysis of the endophilin-3 interactome identified by mass spectrometry uncovered enriched components involved in actin binding (with the highest score). Importantly, we validated that the actin-binding protein phostensin interacted with endophilin-3. Phostensin knockdown restored endophilin-3-mediated up-regulation of Aß clearance. Thus, our findings indicate that miR34a inhibits Aß clearance by targeting endophilin-3 and CTSB at multiple steps including uptake and autophagy-mediated degradation.

MiR-30a targets IL-1α and regulates islet functions as an inflammation buffer and response factor.

Diabetes is an inflammatory disease. Inflammation plays an important role in islet functions. However, the exact mechanisms by which inflammation affects islet functions remain unclear. In this study, we investigated the regulatory effects of miR-30a on inflammation and islet functions. The results indicate that miR-30a serves as an inflammation-resolving buffer factor by targeting interleukin 1a (IL-1α) in immune cells and in islet cells, which might play an important role in inflammation homeostasis. miR-30a ameliorates islet functions in an inflammatory micro-environment by targeting the IL-1α/nuclear factor kappa B (NFKB) p65 subunit (p65)/p62 (SQSTM1)/insulin axis, which can be developed into a novel antidiabetic approach. miR-30a serves as a promising inflammation-response biomarker in inflammatory diseases and is possibly activated by the toll-like receptor 4 (TLR4)/IL-1α/NFKB pathways. However, the exact molecular mechanisms by which miR-30a regulates inflammation and islet functions as well as the potential applications in transitional medicine require further elucidation.

Relationship between LINC00341 expression and cancer prognosis.

LINC00341 is a novel long intergenic non-protein coding RNA with unknown functions. In our report, we investigated LINC00341 expression and its prognostic value in cancer patients. DNA over-methylation triggered low expression of LINC00341 and that was associated with poor prognosis in cancers. A meta-analysis further confirmed that high expression of LINC00341 was associated with a better prognosis in cancer patients. Both gene set enrichment analysis and meta-analysis showed that LINC00341 inhibited cancer metastasis. Finally, a large-scale multicentre analysis supported a prognostic value of LINC00341 in cancers.

MicroRNA-181a suppresses parkin-mediated mitophagy and sensitizes neuroblastoma cells to mitochondrial uncoupler-induced apoptosis.

Damage to mitochondria often results in the activation of both mitophagy and mitochondrial apoptosis. The elimination of dysfunctional mitochondria is necessary for mitochondrial quality maintenance and efficient energy supply. Here we report that miR-181a is a novel inhibitor of mitophagy. miR-181a is downregulated by mitochondrial uncouplers in human neuroblastoma SH-SY5Y cells. Overexpression of miR-181a inhibits mitochondrial uncoupling agents-induced mitophagy by inhibiting the degradation of mitochondrial proteins without affecting global autophagy. Knock down of endogenous miR-181a accelerates the autophagic degradation of damaged mitochondria. miR-181a directly targets Parkin E3 ubiquitin ligase and partially blocks the colocalization of mitochondria and autophagosomes/lysosomes. Re-expression of exogenous Parkin restores the inhibitory effect of miR-181a on mitophagy. Furthermore, miR-181a increases the sensitivity of neuroblastoma cells to mitochondrial uncoupler-induced apoptosis, whereas miR-181a antagomir prevents cell death. Because mitophagy defects are associated with a variety of human disorders, these findings indicate an important link between microRNA and Parkin-mediated mitophagy and highlights a potential therapeutic strategy for human diseases.

Characterization of the microRNA pool and the factors affecting its regulatory potential.

The regulation of gene expression by microRNAs (miRNAs) is complex due to a number of variables involved. The potential for one miRNA to target many genes, the presence of multiple miRNA response elements (MREs) in one mRNA molecule and the interplay between RNAs that share common MREs each add a layer of complexity to the process; making it difficult to determine how regulation of gene expression by miRNAs works within the context of the system as a whole. In this study, we used luciferase report vectors inserted with different 3'UTR fragments as probes to detect the repressive effect of the miRNA pool on gene expression and uncovered some essential characteristics of gene regulation mediated by the miRNA pool, such as the nonlinear correlative relationship between the regulatory potential of a miRNA pool and the number of potential MREs, the buffering effect and the saturating effect of the miRNA pool, and the restrictive effect caused by the density of MREs. Through expressing gradient concentration of 3'UTR fragments, we indirectly detected the regulatory potential of the competing endogenous RNA (ceRNA) pool and analysed its effect on the regulatory potential of the miRNA pool. Our results provide some new insights into miRNA pool mediated gene regulation.

Hypoxia-induced MIR155 is a potent autophagy inducer by targeting multiple players in the MTOR pathway.

Hypoxia activates autophagy, an evolutionarily conserved cellular catabolic process. Dysfunction in the autophagy pathway has been implicated in an increasing number of human diseases, including cancer. Hypoxia induces upregulation of a specific set of microRNAs (miRNAs) in a variety of cell types. Here, we describe hypoxia-induced MIR155 as a potent inducer of autophagy. Enforced expression of MIR155 increases autophagic activity in human nasopharyngeal cancer and cervical cancer cells. Knocking down endogenous MIR155 inhibits hypoxia-induced autophagy. We demonstrated that MIR155 targets multiple players in MTOR signaling, including RHEB, RICTOR, and RPS6KB2. MIR155 suppresses target-gene expression by directly interacting with their 3' untranslated regions (UTRs), mutations of the binding sites abolish their MIR155 responsiveness. Furthermore, by downregulating MTOR signaling, MIR155 also attenuates cell proliferation and induces G 1/S cell cycle arrest. Collectively, these data present a new role for MIR155 as a key regulator of autophagy via dysregulation of MTOR pathway.