HNRNPU promotes the progression of triple-negative breast cancer via RNA transcription and alternative splicing mechanisms

Pathogenic gene connections in type 2 diabetes and non-alcoholic fatty liver disease: a bioinformatics analysis and mouse model investigations experiments

BACKGROUND

Type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD) are prevalent metabolic disorders with overlapping pathophysiological mechanisms. A comprehensive understanding of the shared molecular pathways involved in these conditions can advance the development of effective therapeutic interventions.

METHODS

We used two datasets sourced from the Gene Expression Omnibus (GEO) database to identify common differentially expressed genes (DEGs) between T2D and NAFLD. Subsequently, we conducted Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses to identify the enriched biological processes and signaling pathways. In addition, we performed a protein-protein interaction (PPI) network analysis to identify hub genes with pivotal roles. To validate our findings, we established a type 2 diabetic mouse model with NAFLD.

RESULTS

Our analysis identified 53 DEGs shared between T2D and NAFLD. Enrichment analysis revealed their involvement in signal transduction, transcriptional regulation, and cell proliferation as well as in the ferroptosis signaling pathways. PPI network analysis identified ten hub genes, namely CD44, CASP3, FYN, KLF4, HNRNPM, HNRNPU, FUBP1, RUNX1, NOTCH3, and ANXA2. We validated the differential expression of FYN, HNRNPU, and FUBP1 in liver tissues of a type 2 diabetic mouse model with NAFLD.

CONCLUSIONS

Our study offers valuable insights into the shared molecular mechanisms underlying T2D and NAFLD. The identified hub genes and pathways present promising prospects as therapeutic targets to address these prevalent metabolic disorders.

Decreased RNA-binding protein heterogeneous nuclear ribonucleoprotein U improves multiple myeloma sensitivity to lenalidomide

Multiple myeloma (MM) is an incurable plasma cell cancer in the bone marrow. Immunomodulatory drugs, such as lenalidomide (LEN) and pomalidomide, are backbone agents in MM treatment, and LEN resistance is commonly seen in the MM clinic. In this study, we presented that heterogeneous nuclear ribonucleoprotein U (hnRNPU) affected MM resistance to LEN via the regulation of target mRNA translation. hnRNPULow MM cells exhibited upregulated CRBN and IKZF1 proteins, stringent IKZF1/3 protein degradation upon LEN addition and increased sensitivity to LEN. RNA pulldown assays and RNA electrophoretic mobility shift assays revealed that hnRNPU bound to the 3'-untranslated region of CRBN and IKZF1 mRNA. A sucrose gradient assay suggested that hnRNPU specifically regulated CRBN and IKZF1 mRNA translation. The competition of hnRNPU binding to its target mRNAs by small RNAs with hnRNPU-binding sites restored MM sensitivity to LEN. hnRNPU function in vivo was confirmed in an immunocompetent MM mouse model constructed by the inoculation of Crbn-humanized murine 5TGM1 cells into CrbnI391V/+ mice. Overall, this study suggests a novel mechanism of LEN sensitivity in which hnRNPU represses CRBN and IKZF1 mRNA translation.

Biological functions and clinic significance of SAF‑A (Review)

As one member of the heterogeneous ribonucleoprotein (hnRNP) family, scaffold attachment factor A (SAF-A) or hnRNP U, is an abundant nuclear protein. With RNA and DNA binding activities, SAF-A has multiple functions. The present review focused on the biological structure and different roles of SAF-A and SAF-A-related diseases. It was found that SAF-A maintains the higher-order chromatin organization via RNA and DNA, and regulates transcription at the initiation and elongation stages. In addition to regulating pre-mRNA splicing, mRNA transportation and stabilization, SAF-A participates in double-strand breaks and mitosis repair. Therefore, the aberrant expression and mutation of SAF-A results in tumors and impaired neurodevelopment. Moreover, SAF-A may play a role in the anti-virus system. In conclusion, due to its essential biological functions, SAF-A may be a valuable clinical prediction factor or therapeutic target. Since the role of SAF-A in tumors and viral infections may be controversial, more animal experiments and clinical assays are needed.

Circular RNA CircSLC22A23 Promotes Gastric Cancer Progression by Activating HNRNPU Expression

BACKGROUND

Circular RNAs (CircRNAs) play essential roles in cancer occurrence as regulatory RNAs. However, circRNA-mediated regulation of gastric cancer (GC) remains poorly understood.

AIM

The purpose of this study was to investigate the molecular mechanism of circSLC22A23 (hsa_circ_0075504) underlying GC occurrence.

METHODS

CircSLC22A23 levels were first quantified by quantitative real-time reverse transcription-polymerase chain reaction in GC cell lines, 80 paired GC tissues and adjacent normal tissues, and 27 pairs of plasma samples from preoperative and postoperative patients with GC. Then circSLC22A23 was knocked-down with short hairpin RNA to analyze its oncogenic effects on the proliferation, migration, and invasion of GC cells. Finally, circRNA-binding proteins and their downstream target genes were identified by RNA pulldown, mass spectrometry, RNA immunoprecipitation, quantitative real-time reverse transcription-polymerase chain reaction, and Western blot assays.

RESULTS

CircSLC22A23 was found to be highly expressed in GC cells, GC tissues, and plasma from GC patients. Knockdown of circSLC22A23 inhibited GC cell proliferation, migration and invasion. RNA pulldown and RNA immunoprecipitation assays verified the interaction between circSLC22A23 and heterogeneous nuclear ribonucleoprotein U (HNRNPU). Knockdown of circSLC22A23 decreased HNRNPU protein levels. Moreover, rescue assays showed that the tumor suppressive effect of circSLC22A23 knockdown was reversed by HNRNPU overexpression. Finally, epidermal growth factor receptor (EGFR) was found to be one of the downstream target genes of HNRNPU that was up regulated by circSLC22A23.

CONCLUSION

CircSLC22A23 regulated the transcription of EGFR through activation of HNRNPU in GC cells, suggesting that circSLC22A23 may serve as a potential therapeutic target for the treatment of GC.

Alternative splicing and related RNA binding proteins in human health and disease

Alternative splicing (AS) serves as a pivotal mechanism in transcriptional regulation, engendering transcript diversity, and modifications in protein structure and functionality. Across varying tissues, developmental stages, or under specific conditions, AS gives rise to distinct splice isoforms. This implies that these isoforms possess unique temporal and spatial roles, thereby associating AS with standard biological activities and diseases. Among these, AS-related RNA-binding proteins (RBPs) play an instrumental role in regulating alternative splicing events. Under physiological conditions, the diversity of proteins mediated by AS influences the structure, function, interaction, and localization of proteins, thereby participating in the differentiation and development of an array of tissues and organs. Under pathological conditions, alterations in AS are linked with various diseases, particularly cancer. These changes can lead to modifications in gene splicing patterns, culminating in changes or loss of protein functionality. For instance, in cancer, abnormalities in AS and RBPs may result in aberrant expression of cancer-associated genes, thereby promoting the onset and progression of tumors. AS and RBPs are also associated with numerous neurodegenerative diseases and autoimmune diseases. Consequently, the study of AS across different tissues holds significant value. This review provides a detailed account of the recent advancements in the study of alternative splicing and AS-related RNA-binding proteins in tissue development and diseases, which aids in deepening the understanding of gene expression complexity and offers new insights and methodologies for precision medicine.

Design, Synthesis, and Biological Evaluation of 2-Substituted Aniline Pyrimidine Derivatives as Potent Dual Mer/c-Met Inhibitors

Mer and c-Met kinases, which are commonly overexpressed in various tumors, are ideal targets for the development of antitumor drugs. This study focuses on the design, synthesis, and evaluation of several 2-substituted aniline pyrimidine derivatives as highly potent dual inhibitors of Mer and c-Met kinases for effective tumor treatment. Compound 18c emerged as a standout candidate, demonstrating robust inhibitory activity against Mer and c-Met kinases, with IC50 values of 18.5 ± 2.3 nM and 33.6 ± 4.3 nM, respectively. Additionally, compound 18c displayed good antiproliferative activities on HepG2, MDA-MB-231, and HCT116 cancer cells, along with favorable safety profiles in hERG testing. Notably, it exhibited exceptional liver microsomal stability in vitro, with a half-life of 53.1 min in human liver microsome. Compound 18c also exhibited dose-dependent cytotoxicity and hindered migration of HCT116 cancer cells, as demonstrated in apoptosis and migration assays. These findings collectively suggest that compound 18c holds promise as a dual Mer/c-Met agent for cancer treatment.

Alternative Splicing Factor Heterogeneous Nuclear Ribonucleoprotein U as a Promising Biomarker for Gastric Cancer Risk and Prognosis with Tumor-Promoting Properties

Gastric cancer (GC) is a major global health concern with poor outcomes. Heterogeneous nuclear ribonucleoprotein U (HNRNPU) is a multifunctional protein that participates in pre-mRNA packaging, alternative splicing regulation, and chromatin remodeling. Its potential role in GC remains unclear. In this study, the expression characteristics of HNRNPU were analyzed by The Cancer Genome Atlas data, Gene Expression Omnibus data, and then further identified by real-time quantitative PCR and immunohistochemistry using tissue specimens. From superficial gastritis, atrophic gastritis, and hyperplasia to GC, the in situ expression of HNRNPU protein gradually increased, and the areas under the curve for diagnosis of GC and its precancerous lesions were 0.911 and 0.847, respectively. A nomogram integrating HNRNPU expression, lymph node metastasis, and other prognostic indicators exhibited an area under the curve of 0.785 for predicting survival risk. Knockdown of HNRNPU significantly inhibited GC cell proliferation, migration, and invasion and promoted apoptosis in vitro. In addition, RNA-sequencing analysis showed that HNRNPU could affect alternative splicing events in GC cells, with functional enrichment analysis revealing that HNRNPU may exert malignant biological function in GC progression through alternative splicing regulation. In summary, the increased expression of HNRNPU was significantly associated with the development of GC, with a good performance in diagnosing and predicting the prognostic risk of GC. Functionally, HNRNPU may play an oncogenic role in GC by regulating alternative splicing.

FAM171B stabilizes vimentin and enhances CCL2-mediated TAM infiltration to promote bladder cancer progression

BACKGROUND

Invasion and metastasis are the main causes of unfavourable prognosis in patients diagnosed with bladder cancer. The efficacy of immunotherapy in bladder cancer remains suboptimal due to the presence of an immunosuppressive microenvironment. The novel protein family with sequence similarity 171B (FAM171B) has been identified, but its precise role and mechanism in bladder cancer remain unclear.

METHODS

In this study, we conducted an analysis to investigate the associations between FAM171B expression and the prognosis and clinicopathological stage of bladder cancer. To this end, we utilized RNA sequencing data from the TCGA and GEO databases, as well as tumor tissue specimens obtained from our clinical centre. RNA sequencing analysis allowed us to examine the biological function of FAM171B at the transcriptional level in bladder cancer cells. Additionally, we used immunoprecipitation and mass spectrometry to identify the protein that interacts with FAM171B in bladder cancer cells. The effects of FAM171B on modulating tumor-associated macrophages (TAMs) and vimentin-mediated tumor progression, as well as the underlying mechanisms, were clarified by phalloidin staining, immunofluorescence staining, ELISA, RNA immunoprecipitation, flow cytometry and a bladder cancer graft model.

RESULTS

FAM171B expression exhibits strong positive correlation with poor survival outcomes and advanced clinicopathological stages in patients with bladder cancer. FAM171B significantly promoted bladder cancer growth and metastasis, accompanied by TAM accumulation in the microenvironment, in vivo and in vitro. Through studies of the molecular mechanism, we found that FAM171B contributes to tumor progression by stabilizing vimentin in the cytoplasm. Additionally, our research revealed that FAM171B enhances the splicing of CCL2 mRNA by interacting with heterogeneous nuclear ribonucleoprotein U (HNRNPU), ultimately leading to increased recruitment and M2 polarization of TAMs.

CONCLUSIONS

In this study, we identified FAM171B as a potent factor that promotes the progression of bladder cancer. These findings establish a solid theoretical foundation for considering FAM171B as a potential diagnostic and therapeutic biomarker for bladder cancer.

m6A reading protein RBMX as a biomarker for prognosis and tumor progression in esophageal cancer

Background

As a member of m6A methylated binding protein, RNA binding motif protein X-linked (RBMX) has been reported to be associated with tumor invasion, metastasis and prognosis. However, the prognostic significance of RBMX expression in esophageal cancer (ESCA) remains unclear.

Methods

Based on the TIMER database, GEPIA database, cBioPortal database, CIBERSORT deconvolution algorithm, String-DB database, LinkedOmics database, etc., the RBMX expression level, mRNA expression level, prognostic relationship, genetic mutation, immune cell infiltration level, protein interaction network, differential co-expression genes and functional enrichment in esophageal carcinoma were analyzed. Immunohistochemistry was used to detect the expression of RBMX in 53 cases of esophageal carcinoma and adjacent esophageal tissues.

Results

The RBMX expression in ESCA tissue was significantly higher than that in the normal tissues. The overall survival (OS) of patients with high RBMX expression was significantly lower than that of patients with low expression (P=0.04). The protein encoded by the RBMX gene appeared to copy number amplification, mutation and deep deletion. The expression level of RBMX was positively correlated with the levels of follicular helper T cells, eosinophils and initial B cells (P<0.05). Genes significantly and positively correlated with RBMX expression included HNRNPA1L2, SFRS13A, HNRNPA1, etc., which were mainly enriched in biological processes (BPs) such as cell division, mRNA splicing, RNA binding and mRNA 3'-UTR binding.

Conclusions

RBMX may be as a biomarker of poor prognosis of ESCA. RBMX is closely related to the survival and prognosis, genetic mutation and immune cell infiltration of patients with ESCA.

Hypoxia inducible factor-1α (HIF-1α) in breast cancer: The crosstalk with oncogenic and onco-suppressor factors in regulation of cancer hallmarks

Low oxygen level at tumor microenvironment leads to a condition, known as hypoxia that is implicated in cancer progression. Upon hypoxia, HIF-1α undergoes activation and due to its oncogenic function and interaction with other molecular pathways, promotes tumor progression. The HIF-1α role in regulating breast cancer progression is described, Overall, HIF-1α has upregulation in breast tumor and due to its tumor-promoting function, its upregulation is in favor of breast tumor progression. HIF-1α overexpression prevents apoptosis in breast tumor and it promotes cell cycle progression. Silencing HIF-1α triggers cycle arrest and decreases growth. Migration of breast tumor enhances by HIF-1α signaling and it mainly induces EMT in providing metastasis. HIF-1α upregulation stimulates drug resistance and radio-resistance in breast tumor. Furthermore, HIF-1α signaling induces immune evasion of breast cancer. Berberine and pharmacological intervention suppress HIF-1α signaling in breast tumor and regulation of HIF-1α by non-coding RNAs occurs. Furthermore, HIF-1α is a biomarker in clinic.

The Cancer Testes Antigen, HORMAD1, is a Tumor-Specific Replication Fork Protection Factor

Tumors frequently activate the expression of genes that are only otherwise required for meiosis. HORMAD1, which is essential for meiotic recombination in multiple species, is expressed in over 50% of human lung adenocarcinoma cells (LUAD). We previously found that HORMAD1 promotes DNA double strand break (DSB) repair in LUAD. Here, we report that HORMAD1 takes on an additional role in protecting genomic integrity. Specifically, we find HORMAD1 is critical for protecting stalled DNA replication forks in LUAD. Loss of HORMAD1 leads to nascent DNA degradation, an event which is mediated by the MRE11-DNA2-BLM pathway. Moreover, following exogenous induction of DNA replication stress, HORMAD1 deleted cells accumulate single stranded DNA (ssDNA). We find that these phenotypes are the result of a lack of RAD51 and BRCA2 loading onto stalled replication forks. Ultimately, loss of HORMAD1 leads to increased DSBs and chromosomal aberrations in response to replication stress. Collectively, our data support a model where HORMAD1 expression is selected to mitigate DNA replication stress, which would otherwise induce deleterious genomic instability.