Elevated HMGN4 expression potentiates thyroid tumorigenesis

Network Analysis Performed on Transcriptomes of Parkinson's Disease Patients Reveals Dysfunction in Protein Translation

Parkinson's disease (PD) is a prevalent neurodegenerative disorder characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra region of the brain. The hallmark pathological feature of PD is the accumulation of misfolded proteins, leading to the formation of intracellular aggregates known as Lewy bodies. Recent data evidenced how disruptions in protein synthesis, folding, and degradation are events commonly observed in PD and may provide information on the molecular background behind its etiopathogenesis. In the present study, we used a publicly available transcriptomic microarray dataset of peripheral blood of PD patients and healthy controls (GSE6613) to investigate the potential dysregulation of elements involved in proteostasis-related processes at the transcriptomic level. Our bioinformatics analysis revealed 375 differentially expressed genes (DEGs), of which 281 were down-regulated and 94 were up-regulated. Network analysis performed on the observed DEGs highlighted a cluster of 36 elements mainly involved in the protein synthesis processes. Different enriched ontologies were related to translation initiation and regulation, ribosome structure, and ribosome components nuclear export. Overall, this data consistently points to a generalized impairment of the translational machinery and proteostasis. Dysregulation of these mechanics has been associated with PD pathogenesis. Understanding the precise regulation of such processes may shed light on the molecular mechanisms of PD and provide potential data for early diagnosis.

The Tardigrade damage suppressor protein Dsup promotes DNA damage in neurons

Tardigrades are microscopic invertebrates, which are capable of withstanding extreme environmental conditions, including high levels of radiation. A Tardigrade protein, Dsup (Damage Suppressor), protects the Tardigrade's DNA during harsh environmental stress and X-rays. When expressed in cancer cells, Dsup protects DNA from single and double-strand breaks (DSBs) induced by radiation, increases survival of irradiated cells, and protects DNA from reactive oxygen species. These unusual properties of Dsup suggested that understanding how the protein functions may help in the design of small molecules that could protect humans during radiotherapy or space travel. Here, we investigated if Dsup is protective in cortical neurons cultured from rat embryos. We discovered that, in cortical neurons, the codon-optimized Dsup localizes to the nucleus and, surprisingly, promotes neurotoxicity leading to neurodegeneration. Unexpectedly, we found that Dsup expression results in the formation of DNA DSBs in cultured neurons. With electron microscopy, we discovered that Dsup promotes chromatin condensation. Unlike Dsup's protective properties in cancerous cells, in neurons, Dsup promotes neurotoxicity, induces DNA damage, and rearranges chromatin. Taken together, neurons are sensitive to Dsup, and Dsup is a doubtful surrogate for DNA protection in neuronal cells.

Expression, tumor immune infiltration, and prognostic impact of HMGs in gastric cancer

Background

In the past decade, considerable research efforts on gastric cancer (GC) have been expended, however, little advancement has been made owing to the lack of effective biomarkers and treatment options. Herein, we aimed to examine the levels of expression, mutations, and clinical relevance of HMGs in GC to provide sufficient scientific evidence for clinical decision-making and risk management.

Methods

GC samples were obtained from The Cancer Genome Atlas (TCGA). University of California Santa Cruz (UCSC) XENA, Human Protein Atlas (HPA), Gene Expression Profiling Interactive Analysis (GEPIA), Kaplan-Meier Plotter, cBioPortal, GeneMANIA, STRING, LinkedOmics, and DAVID databases were employed. The "ggplot2" package in the R software (×64 3.6.3) was used to thoroughly analyze the effects of HMGs. qRT-PCR was performed to assess HMG levels in GC cell lines.

Results

A total of 375 GC tissues and 32 paraneoplastic tissues were analyzed. The levels of HMGA1, HMGA2, HMGB1, HMGB2, HMGB3, HMGN1, HMGN2, and HMGN4 expression were increased in GC tissues relative to normal gastric tissues. HMGA1, HMGA2, HMGB1, HMGB2, and HMGB3 were highly expressed in GC cell lines. The OS was significantly different in the group showing low expressions of HMGA1, HMGA2, HMGB1, HMGB2, HMGB3, HMGN2, HMGN3, and HMGN5. There was a significant difference in RFS between the groups with low HMGA2, HMGB3, and high HMGN2 expression. The levels of HMGA2, HMGB3, and HMGN1 had a higher accuracy for prediction to distinguish GC from normal tissues (AUC value > 0.9). HMGs were tightly associated with immune infiltration and tumor immune escape and antitumor immunity most likely participates in HMG-mediated oncogenesis in GC. GO and KEGG enrichment analyses showed that HMGs played a vital role in the cell cycle pathway.

Conclusions

Our results strongly suggest a vital role of HMGs in GC. HMGA2 and HMGB3 could be potential markers for prognostic prediction and treatment targets for GC by interrupting the cell cycle pathway. Our findings might provide renewed perspectives for the selection of prognostic biomarkers among HMGs in GC and may contribute to the determination of the optimal strategy for the treatment of these patients.

HMGN5 Escorts Oncogenic STAT3 Signaling by Regulating the Chromatin Landscape in Breast Cancer Tumorigenesis

Cancer progression is highly dependent on the ability of cancer cell tumor formation, in which epigenetic modulation plays an essential role. However, the epigenetic factors promoting breast tumor formation are less known. Screened from three-dimensional (3D)-sphere tumor formation model, HMGN5 that regulates chromatin structures became the candidate therapeutic target in breast cancer, though its role is obscure. HMGN5 is highly expressed in 3D-spheres of breast cancer cells and clinical tumors, also an unfavorable prognostic marker in patients. Furthermore, HMGN5 controls tumor formation and metastasis of breast cancer cells in vitro and in vivo. Mechanistically, HMGN5 is governed by active STAT3 transcriptionally and further escorts STAT3 to shape the oncogenic chromatin landscape and transcriptional program. More importantly, interference of HMGN5 by nanovehicle-packaged siRNA effectively inhibits tumor growth in breast cancer cell-derived xenograft mice model.

IMPLICATIONS

Our findings reveal a novel feed-forward circuit between HMGN5 and STAT3 in promoting breast cancer tumorigenesis and suggest HMGN5 as a novel epigenetic therapeutic target in STAT3-hyperactive breast cancer.

HMGN4 plays a key role in STAT3-mediate oncogenesis of triple-negative breast cancer

High-mobility group nucleosome-binding domain 4 (HMGN4) exerts biological functions by regulating gene transcription through binding with nucleosome. As a new epigenetic regulator discovered in 2001, its biological functions have not been clarified. HMGN4 belongs to HMGNs family, in which HMGN1, 2, and 5 have been reported to play roles in oncogenesis of various cancers. However, it is reported that HMGN4 was associated with thyroid and liver cancer. In this study, we discovered for the first time that HMGN4 was highly expressed in human triple-negative breast cancer (TNBC), based on the analysis of the TCGA database. Moreover, we found that HMGN4 controlled the proliferation of human TNBC cells both in vitro and in vivo. Mechanistically, the positive correlation occurred between HMGN4 and STAT3 downstream genes while HMGN4 played an indispensable role in constitutively active STAT3 (STAT3C) induced colony formation. Interestingly, we reported that STAT3 regulated HMGN4 transcription as its transcriptional factor by ChIP and HMGN4 promoter-luc assays. That is to say, there is a feed-forward signaling circuit between HMGN4 and STAT3, which might control TNBC cell growth. Finally, we proved that the interference of HMGN4 by nanovehicle-packaged siRNA may be a potentially effective approach in TNBC treatment. In summary, our findings not only identified a novel regulator in TNBC cell proliferation but also revealed the mechanism by which HMGN4 acted as a downstream gene of STAT3 to participate in the STAT3 pathway, which indicated that HMGN4 was likely to be a potential novel target for anti-TNBC therapy.

Thyroid and breast cancer in two sisters with monoallelic mutations in the ataxia telangiectasia mutated (ATM) gene

The presence of a bidirectional risk for metachronous carcinomas among women with thyroid and breast cancer is well established. However, the underlying risk factors remain poorly understood.

Two sisters developed papillary thyroid cancer (PTC) at age 32 and 34 years, followed by ductal carcinoma of the breast at 44 and 42 years. The 2 children of the younger sister developed ataxia-telangiectasia; the son also developed lymphoblastic lymphoma and his sister died secondary to acute lymphoblastic leukemia (ALL). They were found to be compound heterozygous for ataxia telangiectasia mutated (ATM) gene mutations (c.3848T>C, p.L1283P; and c.802C>T, p.Q268X). Exome sequencing of the 2 sisters (mother and aunt of the children with ataxia-telangiectasia) led to the detection of the pathogenic monoallelic ATM mutation in both of them (c.3848T>C; minor allele frequency [MAF] < 0.01) but detected no other variants known to confer a risk for PTC or breast cancer.

The findings suggest that monoallelic ATM mutations, presumably in conjunction with additional genetic and/or nongenetic factors, can confer a risk for developing PTC and breast cancer.

Identification of genes associated with Kikuchi-Fujimoto disease using RNA and exome sequencing

Kikuchi-Fujimoto disease (KFD) is an extremely rare disease, and although it is reported to have a worldwide distribution, young Asian women are most likely to be affected. Although this disease is generally benign and self-limiting, distinguishing it from other diseases that cause lymphadenopathy (e.g., leukemia, lymphoma, and infectious diseases) is challenging. A lymph node biopsy is a definitive diagnostic technique for KFD and only requires skillful pathologists. There are no specific symptoms or laboratory tests for KFD, and more than 50% of KFD patients have suffered from being misdiagnosed with lymphoma, which leads to improper treatment. In this study, lymph node tissue samples from KFD patients were used to reveal their exomes and transcriptomes using a high-throughput nucleotide sequencer. Fourteen single nucleotide polymorphisms (SNPs) were identified as candidate KFD markers and were compared with a healthy lymph node exome dataset. The mutation of these genes caused disruptive impact in the proteins. Several SNPs associated with KFD involve genes related to human cancers, olfaction, and osteoblast differentiation. According to the transcriptome data, there were 238 up-regulated and 1,519 down-regulated genes. RANBP2-like and ribosomal protein L13 were the most up-regulated and down-regulated genes in KFD patients, respectively. The altered gene expression involved in the human immune system, chromatin remodeling, and gene transcription. A comparison of KFD and healthy datasets of exomes and transcriptomes may allow further insights into the KFD phenotype. The results may also facilitate future KFD diagnosis and treatment.

Prognostic value of HMGN family expression in acute myeloid leukemia

Aim: The objective of this work was to investigate the prognostic role of the HMGN family in acute myeloid leukemia (AML). Methods: A total of 155 AML patients with HMGN1-5 expression data from the Cancer Genome Atlas database were enrolled in this study. Results: In the chemotherapy-only group, patients with high HMGN2 expression had significantly longer event-free survival (EFS) and overall survival (OS) than those with low expression (all p < 0.05), whereas high HMGN5 expressers had shorter EFS and OS than the low expressers (all p < 0.05). Multivariate analysis identified that high HMGN2 expression was an independent favorable prognostic factor for patients who only received chemotherapy (all p < 0.05). HMGN family expression had no impact on EFS and OS in AML patients receiving allogeneic hematopoietic stem cell transplantation. Conclusion: High HMGN2/5 expression is a potential prognostic indicator for AML.

Changes of protein levels in human urine reflect the dysregulation of signaling pathways of chronic kidney disease and its complications

The increasing prevalence of chronic kidney disease (CKD) seriously is threatening human health and overall quality of life. The discovery of biomarkers of pathogenesis of CKD and the associated complications are very important for CDK diagnosis and treatment. In this paper, urine protein biomarkers were investigated because urine sample collection is convenient and non-invasive. We analyzed the protein concentrations in the urine of CKD patients and extracted abnormal protein signals comparing with the healthy control groups. The enriched signaling pathways that may characterize CKD pathology were identified from these proteins. We applied surface-enhanced laser desorption and ionization time of flight mass spectrometry technology to detect different protein peaks in urine samples from patients with CKD and healthy controls. We searched the proteins corresponding to protein peaks through the UniProt database and identified the signaling pathways of CKD and its complications by using the NIH DAVID database. 42 low abundance proteins and 46 high abundance proteins in the urine samples from CKD patients were found by comparing with healthy controls. Seven KEGG pathways related to CKD and its complications were identified from the regulated proteins. These pathways included chemokine signaling pathway, cytokine-cytokine receptor interaction, oxidative phosphorylation, cardiac muscle contraction, Alzheimer's disease, Parkinson's disease, and salivary secretion. In CKD stages 2, 3, 4, and 5, five proteins showed significantly differential abundances. The differential protein signals and regulated signaling pathways will provide new insight for the pathogenesis of CKD and its complications. These altered proteins may also be used as novel biomarkers for the noninvasive and convenient diagnosis methods of CKD and its complications through urine testing in the future.

Biological Functions of HMGN Chromosomal Proteins

Chromatin plays a key role in regulating gene expression programs necessary for the orderly progress of development and for preventing changes in cell identity that can lead to disease. The high mobility group N (HMGN) is a family of nucleosome binding proteins that preferentially binds to chromatin regulatory sites including enhancers and promoters. HMGN proteins are ubiquitously expressed in all vertebrate cells potentially affecting chromatin function and epigenetic regulation in multiple cell types. Here, we review studies aimed at elucidating the biological function of HMGN proteins, focusing on their possible role in vertebrate development and the etiology of disease. The data indicate that changes in HMGN levels lead to cell type-specific phenotypes, suggesting that HMGN optimize epigenetic processes necessary for maintaining cell identity and for proper execution of specific cellular functions. This manuscript contains tables that can be used as a comprehensive resource for all the English written manuscripts describing research aimed at elucidating the biological function of the HMGN protein family.