UBE2L6 is Involved in Cisplatin Resistance by Regulating the Transcription of ABCB6

Cadmium transport by mammalian ATP-binding cassette transporters

Cellular responses to toxic metals depend on metal accessibility to intracellular targets, reaching interaction sites, and the intracellular metal concentration, which is mainly determined by uptake pathways, binding/sequestration and efflux pathways. ATP-binding cassette (ABC) transporters are ubiquitous in the human body-usually in epithelia-and are responsible for the transfer of indispensable physiological substrates (e.g. lipids and heme), protection against potentially toxic substances, maintenance of fluid composition, and excretion of metabolic waste products. Derailed regulation and gene variants of ABC transporters culminate in a wide array of pathophysiological disease states, such as oncogenic multidrug resistance or cystic fibrosis. Cadmium (Cd) has no known physiological role in mammalians and poses a health risk due to its release into the environment as a result of industrial activities, and eventually passes into the food chain. Epithelial cells, especially within the liver, lungs, gastrointestinal tract and kidneys, are particularly susceptible to the multifaceted effects of Cd because of the plethora of uptake pathways available. Pertinent to their broad substrate spectra, ABC transporters represent a major cellular efflux pathway for Cd and Cd complexes. In this review, we summarize current knowledge concerning transport of Cd and its complexes (mainly Cd bound to glutathione) by the ABC transporters ABCB1 (P-glycoprotein, MDR1), ABCB6, ABCC1 (multidrug resistance related protein 1, MRP1), ABCC7 (cystic fibrosis transmembrane regulator, CFTR), and ABCG2 (breast cancer related protein, BCRP). Potential detoxification strategies underlying ABC transporter-mediated efflux of Cd and Cd complexes are discussed.

Ube2L6 Promotes M1 Macrophage Polarization in High-Fat Diet-Fed Obese Mice via ISGylation of STAT1 to Trigger STAT1 Activation

INTRODUCTION

In obesity-related type 2 diabetes mellitus (T2DM), M1 macrophages aggravate chronic inflammation and insulin resistance. ISG15-conjugation enzyme E2L6 (Ube2L6) has been demonstrated as a promoter of obesity and insulin resistance. This study investigated the function and mechanism of Ube2L6 in M1 macrophage polarization in obesity.

METHODS

Obesity was induced in Ube2L6AKO mice and age-matched Ube2L6flox/flox control mice by high-fat diet (HFD). Stromal vascular cells were isolated from the epididymal white adipose tissue of mice. Polarization induction was performed in mouse bone marrow-derived macrophages (BMDMs) by exposure to IFN-γ, lipopolysaccharide, or IL-4. F4/80 expression was assessed by immunohistochemistry staining. Expressions of M1/M2 macrophage markers and target molecules were determined by flow cytometry, RT-qPCR, and Western blotting, respectively. Protein interaction was validated by co-immunoprecipitation (Co-IP) assay. The release of TNF-α and IL-10 was detected by ELISA.

RESULTS

The polarization of pro-inflammatory M1 macrophages together with an increase in macrophage infiltration was observed in HFD-fed mice, which could be restrained by Ube2L6 knockdown. Additionally, Ube2L6 deficiency triggered the repolarization of BMDMs from M1 to M2 phenotypes. Mechanistically, Ube2L6 promoted the expression and activation of signal transducer and activator of transcription 1 (STAT1) through interferon-stimulated gene 15 (ISG15)-mediated ISGlylation, resulting in M1 macrophage polarization.

CONCLUSION

Ube2L6 exerts as an activator of STAT1 via post-translational modification of STAT1 by ISG15, thereby triggering M1 macrophage polarization in HFD-fed obese mice. Overall, targeting Ube2L6 may represent an effective therapeutic strategy for ameliorating obesity-related T2DM.

Serum Extracellular Vesicle-Derived hsa-miR-2277-3p and hsa-miR-6813-3p Are Potential Biomarkers for Major Depression: A Preliminary Study

The aim of the present study was to examine the association between miRNA levels in extracellular vesicles (EVs) from serum and the severity of Major Depression (MD). Patient sera from 16 MD cases were collected at our university hospital. The miRNAs contained in EVs were extracted using a nanofiltration method, and their expression levels were analyzed using miRNA microarrays. Intergroup comparisons were performed to validate the diagnostic performance of miRNAs in EVs. Furthermore, candidate miRNAs in EVs were added to neural progenitor cells, astrocytes, and microglial cells in vitro, and the predicted target genes of the candidate miRNAs were extracted. The predicted target genes underwent enrichment analysis. The expression levels of hsa-miR-6813-3p and hsa-miR-2277-3p were significantly downregulated with increasing depression severity of MD. The pathway enrichment analysis suggests that hsa-miR-6813-3p may be involved in glucocorticoid receptor and gamma-aminobutyric acid receptor signaling. Additionally, hsa-miR-2277-3p was found to be involved in the dopaminergic neural pathway. The analysis of serum miRNAs in EVs suggests that hsa-miR-6813-3p and hsa-miR-2277-3p could serve as novel biomarkers for MD, reflecting its severity. Moreover, these miRNAs in EVs could help understand MD pathophysiology.

Functional Characteristics of Diverse PAX6 Mutations Associated with Isolated Foveal Hypoplasia

The human fovea is a specialized pit structure in the central retina. Foveal hypoplasia is a condition where the foveal pit does not fully develop, and it is associated with poor vision. Autosomal dominant isolated foveal hypoplasia (FVH1) is a rare condition of foveal hypoplasia (FH) that lacks any other ocular manifestations. FVH1 is associated with hypomorphic mutations in the PAX6 gene that encodes a sequence-specific DNA-binding transcription factor for morphogenesis and evolution of the eye. We report our findings in 17 patients with PAX6 mutations associated with FVH1 or FH with aniridia and corneal opacities. Patients with three mutations, p.V78E, p.V83F and p.R128H, in the C-terminal subdomain of the paired domain (CTS) consistently have severe FH. Luciferase assays for a single reporter containing a representative PAX6 binding site indicated that the transcriptional activities of these mutations were significantly reduced, comparable to that of the truncation mutation of p.G65Rfs*5. Patients with p.P20S in the N-terminal subdomain of the paired domain, and a patient with p.N365K in the proline-serine-threonine-rich domain (PSTD) had mild FH. A patient with p.Q255L in the homeodomain had severe FH. The P20S and Q255L mutants did not affect the transcriptional activity. Mutant N365K has a retained DNA-binding activity but a reduced transcriptional activity, due to a low PSTD transactivation. These findings demonstrated that mutations associated with FVH1 underlie a functional divergence between DNA-binding ability and transcriptional activity. We conclude that a wide range of mutations in the PAX6 gene is not limited to the CST region and are responsible for FVH1.

IL-6-Mediated Upregulated miRNAs in Extracellular Vesicles Derived from Lund Human Mesencephalic (LUHMES) Cells: Effects on Astrocytes and Microglia

Psychological stress plays a major role in depression, and interleukin-6 (IL-6) is elevated during depression and psychological stress. MicroRNAs (miRNAs) in extracellular vesicles (EVs), including exosomes and microvesicles, suppress mRNA expression in other cells when endocytosed. In this study, we analyzed the effect of IL-6 on EVs secreted by neural precursor cells. Cells from the human immortalized neural precursor cell line LUHMES were treated with IL-6. EVs were collected using a nanofiltration method. We then analyzed the uptake of LUHMES-derived EVs by astrocytes (ACs) and microglia (MG). Microarray analysis of miRNAs was performed using EV-incorporated RNA and intracellular RNA from ACs and MG to search for increased numbers of miRNAs. We applied the miRNAs to ACs and MG, and examined the cells for suppressed mRNAs. IL-6 increased several miRNAs in the EVs. Three of these miRNAs were originally low in ACs and MG (hsa-miR-135a-3p, hsa-miR-6790-3p, and hsa-miR-11399). In ACs and MG, hsa-miR-6790-3p and hsa-miR-11399 suppressed four mRNAs involved in nerve regeneration (NREP, KCTD12, LLPH, and CTNND1). IL-6 altered the types of miRNAs in EVs derived from neural precursor cells, by which mRNAs involved in nerve regeneration were decreased in ACs and MG. These findings provide new insights into the involvement of IL-6 in stress and depression.

Systematic Analysis of Molecular Subtypes Based on the Expression Profile of Immune-Related Genes in Pancreatic Cancer

Immunotherapy has a good therapeutic effect and provides a new approach for cancer treatment. However, only limited studies have focused on the use of molecular typing to construct an immune characteristic index for gene expression in pancreatic adenocarcinoma (PAAD) and to assess the effectiveness of immunotherapy in patients with PAAD. Clinical follow-up data and gene expression profile of PAAD patients were retrieved from The Cancer Genome Atlas (TCGA) database. Based on 184 immune features, molecular subtypes of pancreatic cancer were found by the "ConsensusClusterPlus" package, and the association between clinical features and immune cell subtype distribution was analysed. In addition, the relationship between the proportion of immune subtypes and the expression of immune checkpoints was analysed. The CIBERSORT algorithm was introduced to evaluate the immune scores of different molecular subtypes. We used the tumor immune dysfunction and exclusion (TIDE) algorithm to assess the potential clinical effect of immunotherapy interventions on single-molecule subtypes. In addition, the oxidative stress index was constructed by linear discriminant analysis DNA (LDA), and weighted correlation network analysis was performed to identify the core module of the index and its characteristic genes. Expression of hub genes was verified by immunohistochemical analysis in an independent PAAD cohort. Pancreatic cancer is divided into three molecular subtypes (IS1, IS2, and IS3), with significant differences in prognosis between multiple cohorts. Expression of immune checkpoint-associated genes was significantly reduced in IS3 and higher in IS1 and IS2, suggesting that the three subgroups have different responsiveness to immunotherapy interventions. The results of the CIBERSORT analysis showed that IS1 exhibited the highest levels of immune infiltration, whereas the results of the TIDE analysis showed that the T-cell dysfunction score of IS1 was higher than that of IS2 and IS3. Furthermore, IS3 was found to be more sensitive to 5-FU and to have a higher immune signature index than IS1 and IS2. Based on WGCNA analysis, 10 potential gene markers were identified, and their expression at the protein level was verified by immunohistochemical analysis. Specific molecular expression patterns in pancreatic cancer can predict the efficacy of immunotherapy and influence the prognosis of patients.

The Landscape of the Tumor Microenvironment in Skin Cutaneous Melanoma Reveals a Prognostic and Immunotherapeutically Relevant Gene Signature

The tumorigenesis of skin cutaneous melanoma (SKCM) remains unclear. The tumor microenvironment (TME) is well known to play a vital role in the onset and progression of SKCM. However, the dynamic mechanisms of immune regulation are insufficient. We conducted a comprehensive analysis of immune cell infiltration in the TME. Based on the differentially expressed genes (DEGs) in clusters grouped by immune infiltration status, a set of hub genes related to the clinical prognosis of SKCM and tumor immune infiltration was explored. Methods: We analyzed immune cell infiltration in two independent cohorts and assessed the relationship between the internal pattern of immune cell infiltration and SKCM characteristics, including clinicopathological features, potential biological pathways, and gene mutations. Genes related to the infiltration pattern of TME immune cells were determined. Furthermore, the unsupervised clustering method (k-means) was used to divide samples into three different categories according to TME, which were defined as TME cluster-A, -B, and -C. DEGs among three groups of samples were analyzed as signature genes. We further distinguished common DEGs between three groups of samples according to whether differences were significant and divided DEGs into the Signature gene-A group with significant differences and the Signature gene-B group with insignificant differences. The Signature gene-A gene set mainly had exon skipping in SKCM, while the Signature gene-B gene set had no obvious alternative splicing form. Subsequently, we analyzed genetic variations of the two signatures and constructed a competing endogenous RNA (ceRNA) regulatory network. LASSO Cox regression was used to determine the immune infiltration signature and risk score of SKCM. Finally, we obtained 13 hub genes and calculated the risk score based on the coefficient of each gene to explore the impact of the high- and low-risk scores on biologically related functions and prognosis of SKCM patients further. The correlation between the risk score and clinicopathological characteristics of SKCM patients indicated that a low-risk score was associated with TME cluster-A classification (p < 0.001) and metastatic SKCM (p < 0.001). Thirteen hub genes also showed different prognostic effects in pan-cancer. The results of univariate and multivariate Cox analyses revealed that risk score could be used as an independent risk factor for predicting the prognosis of SKCM patients. The nomogram that integrated clinicopathological characteristics and immune characteristics to predict survival probability was based on multivariate Cox regression. Finally, 13 hub genes that showed different prognostic effects in pan-cancers were obtained. According to immunohistochemistry staining results, Ube2L6, SRPX2, and IFIT2 were expressed at higher levels, while CLEC4E, END3, and KIR2DL4 were expressed at lower levels in 25 melanoma specimens. Conclusion: We performed a comprehensive assessment of the immune-associated TME. To elucidate the potential development of immune-genomic features in SKCM, we constructed an unprecedented set of immune characteristic genes (EDN3, CLEC4E, SRPX2, KIR2DL4, UBE2L6, and IFIT2) related to the immune landscape of TME. These genes are related to different prognoses and drug responses of SKCM. The immune gene signature constructed can be used as a robust prognostic biomarker of SKCM and a predictor of an immunotherapy effect.

ATP-binding cassette (ABC) transporters in cancer: A review of recent updates

The ATP-binding cassette (ABC) transporter superfamily is one of the largest membrane protein families existing in wide spectrum of organisms from prokaryotes to human. ABC transporters are also known as efflux pumps because they mediate the cross-membrane transportation of various endo- and xenobiotic molecules energized by ATP hydrolysis. Therefore, ABC transporters have been considered closely to multidrug resistance (MDR) in cancer, where the efflux of structurally distinct chemotherapeutic drugs causes reduced itherapeutic efficacy. Besides, ABC transporters also play other critical biological roles in cancer such as signal transduction. During the past decades, extensive efforts have been made in understanding the structure-function relationship, transportation profile of ABC transporters, as well as the possibility to overcome MDR via targeting these transporters. In this review, we discuss the most recent knowledge regarding ABC transporters and cancer drug resistance in order to provide insights for the development of more effective therapies.

Ubiquitin Proteasome Pathway Transcriptome in Epithelial Ovarian Cancer

In this article, we reviewed the transcription of genes coding for components of the ubiquitin proteasome pathway in publicly available datasets of epithelial ovarian cancer (EOC). KEGG analysis was used to identify the major pathways distinguishing EOC of low malignant potential (LMP) from invasive high-grade serous ovarian carcinomas (HGSOC), and to identify the components of the ubiquitin proteasome system that contributed to these pathways. We identified elevated transcription of several genes encoding ubiquitin conjugases associated with HGSOC. Fifty-eight genes coding for ubiquitin ligases and more than 100 genes encoding ubiquitin ligase adaptors that were differentially expressed between LMP and HGSOC were also identified. Many differentially expressed genes encoding E3 ligase adaptors were Cullin Ring Ligase (CRL) adaptors, and 64 of them belonged to the Cullin 4 DCX/DWD family of CRLs. The data suggest that CRLs play a role in HGSOC and that some of these proteins may be novel therapeutic targets. Differential expression of genes encoding deubiquitinases and proteasome subunits was also noted.

Identification of a novel glycolysis-related gene signature for predicting the prognosis of osteosarcoma patients

Glycolysis ensures energy supply to cancer cells, thereby facilitating tumor progression. Here, we identified glycolysis-related genes that could predict the prognosis of patients with osteosarcoma. We examined 198 glycolysis-related genes that showed differential expression in metastatic and non-metastatic osteosarcoma samples in the TARGET database, and identified three genes (P4HA1, ABCB6, and STC2) for the establishment of a risk signature. Based on the signature, patients in the high-risk group had poor outcomes. An independent Gene Expression Omnibus database GSE21257 was selected as the validation cohort. Receiver operating characteristic curve analysis was performed and the accuracy of predicting the 1- and 3-year survival rates was shown by the areas under the curve. The results were 0.884 and 0.790 in the TARGET database, and 0.740 and 0.759 in the GSE21257, respectively. Furthermore, we applied ESTIMATE algorithm and performed single sample gene set enrichment analysis to compare tumor immunity between high- and low-risk groups. We found that the low-risk group had higher immune scores and immune infiltration levels than the high-risk group. Finally, we chose P4HA1 as a representative gene to verify the function of risk genes in vitro and in vivo and found that P4HA1 could promote the metastasis of osteosarcoma cells. Our study established a novel glycolysis-related risk signature that could predict the prognosis of patients with osteosarcoma.

Association of the Epithelial-Mesenchymal Transition (EMT) with Cisplatin Resistance

Therapy resistance is a characteristic of cancer cells that significantly reduces the effectiveness of drugs. Despite the popularity of cisplatin (CP) as a chemotherapeutic agent, which is widely used in the treatment of various types of cancer, resistance of cancer cells to CP chemotherapy has been extensively observed. Among various reported mechanism(s), the epithelial–mesenchymal transition (EMT) process can significantly contribute to chemoresistance by converting the motionless epithelial cells into mobile mesenchymal cells and altering cell–cell adhesion as well as the cellular extracellular matrix, leading to invasion of tumor cells. By analyzing the impact of the different molecular pathways such as microRNAs, long non-coding RNAs, nuclear factor-κB (NF-ĸB), phosphoinositide 3-kinase-related protein kinase (PI3K)/Akt, mammalian target rapamycin (mTOR), and Wnt, which play an important role in resistance exhibited to CP therapy, we first give an introduction about the EMT mechanism and its role in drug resistance. We then focus specifically on the molecular pathways involved in drug resistance and the pharmacological strategies that can be used to mitigate this resistance. Overall, we highlight the various targeted signaling pathways that could be considered in future studies to pave the way for the inhibition of EMT-mediated resistance displayed by tumor cells in response to CP exposure.