HMG chromosomal proteins in development and disease

HMGA1 is a novel candidate gene for myocardial infarction susceptibility

BACKGROUND

Acute Myocardial infarction (AMI), a leading cause of morbidity and mortality worldwide, is a dreadful acute complication of coronary atherosclerosis. Type 2 diabetes mellitus (T2DM) is associated with an increased risk of developing AMI. The architectural transcription factor high-mobility-group AT-hook 1 (HMGA1) has been involved in atherosclerosis, plaque formation, inflammation, and in the pathogenesis of insulin resistance and T2DM. An association of the HMGA1 rs146052672 variant with T2DM has been recently reported. Thus, our aim was to evaluate whether this variant was also associated with AMI.

METHODS AND RESULTS

In a case-control study from Calabria (Southern Italy), we enrolled 254 consecutive, unrelated, patients with first diagnosis of AMI, and 508 age, sex-matched controls. Genotyping of the rs146052672 was performed using the TaqMan allelic discrimination method. We found that this variant was present in 7.9% of AMI patients and in 3.1% of controls (p=0.003). Multiple logistic regression confirmed that the rs146052672 was significantly associated with AMI (OR=2.54; p=0.002), and this association was independent of classical cardiovascular risk factors such as gender, hypertension, obesity and T2DM (for all, p<0.05).

CONCLUSIONS

Our findings demonstrate that a relationship exists between the HMGA1 rs146052672 variant and AMI, suggesting that defects at the HMGA1 locus may play a pathogenetic role in AMI, in the absence of T2DM and other cardiovascular risk factors.

Transcriptional Coactivator and Chromatin Protein PC4 Is Involved in Hippocampal Neurogenesis and Spatial Memory Extinction

Although the elaborate combination of histone and non-histone protein complexes defines chromatin organization and hence regulates numerous nuclear processes, the role of chromatin organizing proteins remains unexplored at the organismal level. The highly abundant, multifunctional, chromatin-associated protein and transcriptional coactivator positive coactivator 4 (PC4/Sub1) is absolutely critical for life, because its absence leads to embryonic lethality. Here, we report results obtained with conditional PC4 knock-out (PC4(f/f) Nestin-Cre) mice where PC4 is knocked out specifically in the brain. Compared with the control (PC4(+/+) Nestin-Cre) mice, PC4(f/f) Nestin-Cre mice are smaller with decreased nocturnal activity but are fertile and show no motor dysfunction. Neurons in different areas of the brains of these mice show sensitivity to hypoxia/anoxia, and decreased adult neurogenesis was observed in the dentate gyrus. Interestingly, PC4(f/f) Nestin-Cre mice exhibit a severe deficit in spatial memory extinction, whereas acquisition and long term retention were unaffected. Gene expression analysis of the dorsal hippocampus of PC4(f/f) Nestin-Cre mice revealed dysregulated expression of several neural function-associated genes, and PC4 was consistently found to localize on the promoters of these genes, indicating that PC4 regulates their expression. These observations indicate that non-histone chromatin-associated proteins like PC4 play a significant role in neuronal plasticity.

Pancreatic cyst fluid concentration of high-mobility group A2 protein acts as a differential biomarker of dysplasia in intraductal papillary mucinous neoplasm

BACKGROUND AND AIMS

No reliable cyst fluid biomarkers exist that allow preoperative identification of patients with intraductal papillary mucinous neoplasms (IPMNs) and high-risk pathology. High-mobility group (HMG) A2 protein has been demonstrated to be a biomarker of dysplasia in IPMNs. It is unknown whether HMGA2 protein is present in the cyst fluid from IPMNs. The aims of this study were to determine whether HMGA2 protein is present in the cyst fluid of IPMNs and demonstrate whether HMGA2 protein concentration correlates with the degree of dysplasia.

METHODS

Patients with surgically resected IPMNs and banked pancreatic cyst fluid were identified. Low-risk IPMNs (low-grade [LGD] or moderate dysplasia [MD]) and high-risk IPMNs (high-grade dysplasia [HGD] or invasive cancer) were identified. Pancreatic cyst fluid concentrations of HMGA2 protein were measured via enzyme-linked immunosorbent assay.

RESULTS

Samples from 31 patients were analyzed. HMGA2 protein was detected in the cyst fluid of 30 of 31 specimens (97%). Median cyst fluid HMGA2 protein concentration (ng/mL) was as follows: LGD, 0.6 (interquartile range [IQR] 0.35-0.6); MD, 1.55 (IQR 0.65-2.7); HGD, 4.2 (IQR 1.7-9.2) (P < .05). The median HMGA2 protein concentration was significantly higher in the HGD group (4.2 ng/mL, IQR 1.7-9.2) compared with the concentration in the low-risk group (1.1 ng/mL, IQR 0.6-2.7, P = .03).

CONCLUSION

HMGA2 protein is present in IPMN cyst fluid. Significantly higher concentrations of cyst fluid HMGA2 protein are found in IPMNs with HGD compared with lesions with LGD or MD. Cyst fluid concentrations of HMGA2 protein may thus serve as a biomarker to differentiate patients with high-risk IPMNs from those with low-risk IPMNs.

Alarmins and Antitumor Immunity

PURPOSE

Alarmins are constitutively present endogenous molecules that essentially act as early warning signals for the immune system. We provide a brief overview of major alarmins and highlight their roles in tumor immunity.

METHODS

We searched PubMed up to January 10, 2016, using alarmins and/or damage-associated molecular patterns (DAMPs), as key words. We selected and reviewed articles that focused on the discovery and functions of alarmin and their roles in tumor immunity.

FINDINGS

Alarmins are essentially endogenous immunostimulatory DAMP molecules that are exposed in response to danger (eg, infection or tissue injury) as a result of degranulation, cell death, or induction. They are sensed by chemotactic receptors and pattern recognition receptors to induce immune responses by promoting the recruitment and activation of leukocytes, particularly antigen-presenting cells.

IMPLICATIONS

Accumulating data suggest that certain alarmins, High-mobility group nucleosome-binding protein 1 (HMGN1) in particular, contribute to the generation of antitumor immunity. Some alarmins can also be used as cancer biomarkers. Therefore, alarmins can potentially be applied for our fight against cancers.

Sepsis: in search of cure

INTRODUCTION

Sepsis is a complex inflammatory disorder believed to originate from an infection by any types of microbes and/or their products. It is the leading cause of death in intensive care units (ICUs) throughout the globe. The mortality rates depend both on the severity of infection and the host's response to infection.

METHODS

Literature survey on pathobiology of sepsis in general and failure of more than hundred clinical trials conducted so far in search of a possible cure for sepsis resulted in the preparation of this manuscript.

FINDINGS

Sepsis lacks a suitable animal model that mimics human sepsis. However, based on the results obtained in animal models of sepsis, clinical trials conducted so far have been disappointing. Although involvement of multiple mediators and pathways in sepsis has been recognized, only few components are being targeted and this could be the major reason behind the failure of clinical trials.

CONCLUSION

Inability to recognize a single critical mediator of sepsis may be the underlying cause for the poor therapeutic intervention of sepsis. Therefore, sepsis is still considered as a disease-in search of cure.

HMGB1 induces apoptosis and EMT in association with increased autophagy following H/R injury in cardiomyocytes

Hypoxia/reoxygenation (H/R) is a critical factor in the pathogenesis of tissue injury following myocardial infarction (MI) which can lead to tissue damage and pathological remodeling. Therefore, it is necessary to try and prevent myocardial H/R injury in order to optimize the treatment of MI. This study aimed to explore the functions and molecular mechanisms of action of high mobility group box 1 (HMGB1) and its role in H/R injury to H9c2 cells. The mRNA expression of levels genes were detected by RT-qPCR. The protein levels were examined by western blot analysis. The Beclin 1 expression level was further determined by immunocytochemistry (ICC). In addition, an HMGB1 overexpression vector and a shRNA lentiviral vector were constructed in order to induce the overexpression and silencing of HMGB1, respectively. The apoptotic rate of the H9c2 cells was determined by flow cytometry. The expression of miR-210 was markedly increased following the exposure of the cells to H/R, thus indicating that the cell model of H/R injury was successfully established. In addition, an in vivo model of MI was also created using rats. The mRNA and protein level of HMGB1 was found to be upregulated in the myocardial tissue of the rats with MI and in the H9c2 cells subjected to H/R injury. HMGB1 promoted apoptosis by increasing the expression of cleaved caspase-3 and the apoptotic rate of the cells, while decreasing the expression of Bcl-2 during H/R in the H9c2 cells. HMGB1 promoted epithelial-to-mesenchymal transition (EMT) by reducing the protein level of the epithelial marker, E-cadherin, while increasing the expression of the mesenchymal markers, vimentin and fibroblast-specific protein (FSP), during H/R in the H9c2 cells. HMGB1 induced the apoptosis of the H9c2 cells and EMT following H/R in association with the induction of autophagy. HMGB1 induced autophagy by upregulating the expression of discoidin domain receptor 1 (DDR1) and downregulating the phosphorylation levels of mammalian target of rapamycin (mTOR). In conclusion, the findings of our study suggest that HMGB1 promotes apoptosis and EMT in association with the induction of autophagy through the upregulation of the expression of DDR1 and the downregulation of the phosphorylation of mTOR following H/R injury in H9c2 cells.

HMGB2 regulates satellite cell-mediated skeletal muscle regeneration via IGF2BP2

Although the mechanism underlying modulation of transcription factors in myogenesis has been well elucidated, the function of the transcription cofactors involved in this process remains poorly understood. Here, we identified HMGB2 as an essential nuclear transcriptional co-regulator in myogenesis. HMGB2 was highly expressed in undifferentiated myoblasts and regenerating muscle. Knockdown of HMGB2 inhibited myoblast proliferation and stimulated its differentiation. HMGB2 depletion down-regulated Myf5 and Cyclin A2 on the protein but not mRNA level. In contrast, overexpression of HMGB2 promoted Myf5 and Cyclin A2 protein upregulation. Furthermore, we found that the RNA-binding protein IGF2BP2 is a downstream target of HMGB2, as previously shown for HMGA2. IGF2BP2 binds to mRNAs of Myf5 or Cyclin A2, resulting in translation enhancement or mRNA stabilization, respectively. Notably, overexpression of IGF2BP2 could partially rescue protein levels of Myf5 and Cyclin A2, in response to HMGB2 decrease. Moreover, depletion of HMGB2 in vivo severely attenuated muscle repair; this was due to a decrease in satellite cells. Together, these results highlight the previously undiscovered and critical role of HMGB2-IGF2BP2 axis in myogenesis and muscle regeneration.

Research advances in HMGN5 and cancer

High-mobility group nucleosome-binding domain 5 (HMGN5) is a new member of the high-mobility group N (HMGN) protein family that is involved in nucleosomal binding and transcriptional activation. It was first discovered in mouse, and recent studies found that the expressions of HMGN5 in many human cancers were also highly regulated, such as prostate, bladder, breast, and lung and clear cell renal cell carcinoma. Numerous reports have demonstrated that HMGN5 plays significant roles in many biological and pathological conditions, such as in developmental defects, hypersensitivity to stress, embryonic stem cell differentiation, and tumor progression. Importantly, deficiency of HMGN5 has been shown to be linked to cancer cell growth, cell cycle regulation, migration, invasion, and clinical outcomes, and it represents a promising therapeutic target for many malignant tumors. In the present review, we provide an overview of the current knowledge concerning the role of HMGN5 in cancer development and progression.

Association between HMGB1 and COPD: A Systematic Review

HMGB1 is an alarmin, a protein that warns and activates inflammation. Chronic obstructive pulmonary disease (COPD) is characterised by a progressive airflow obstruction and airway inflammation. Current anti-inflammatory therapies are poorly effective in maintaining lung function and symptoms of COPD. This underlines the need for finding new molecular targets involved in disease pathogenesis in order to block pathology progression. This review aims to analyse latest advances on HMGB1 role, utilisation, and potential application in COPD. To this purpose we reviewed experimental studies that investigated this alarmin as marker as well as a potential treatment in chronic obstructive pulmonary disease. This systematic review was conducted according to PRISMA guidelines. In almost all the studies, it emerged that HMGB1 levels are augmented in smokers and in patients affected by COPD. It emerged that cigarette smoking, the most well-known causative factor of COPD, induces neutrophils death and necrosis. The necrosis of neutrophil cells leads to HMGB1 release, which recruits other neutrophils in a self-maintaining process. According to the results reported in the paper both inhibiting HMGB1 and its receptor (RAGE) and blocking neutrophils necrosis (inducted by cigarette smoking) could be the aim for further studies.

Extracellular high-mobility group box 1 mediates pressure overload-induced cardiac hypertrophy and heart failure

Inflammation plays a key role in pressure overload-induced cardiac hypertrophy and heart failure, but the mechanisms have not been fully elucidated. High-mobility group box 1 (HMGB1), which is increased in myocardium under pressure overload, may be involved in pressure overload-induced cardiac injury. The objectives of this study are to determine the role of HMGB1 in cardiac hypertrophy and cardiac dysfunction under pressure overload. Pressure overload was imposed on the heart of male wild-type mice by transverse aortic constriction (TAC), while recombinant HMGB1, HMGB1 box A (a competitive antagonist of HMGB1) or PBS was injected into the LV wall. Moreover, cardiac myocytes were cultured and given sustained mechanical stress. Transthoracic echocardiography was performed after the operation and sections for histological analyses were generated from paraffin-embedded hearts. Relevant proteins and genes were detected. Cardiac HMGB1 expression was increased after TAC, which was accompanied by its translocation from nucleus to both cytoplasm and intercellular space. Exogenous HMGB1 aggravated TAC-induced cardiac hypertrophy and cardiac dysfunction, as demonstrated by echocardiographic analyses, histological analyses and foetal cardiac genes detection. Nevertheless, the aforementioned pathological change induced by TAC could partially be reversed by HMGB1 inhibition. Consistent with the in vivo observations, mechanical stress evoked the release and synthesis of HMGB1 in cultured cardiac myocytes. This study indicates that the activated and up-regulated HMGB1 in myocardium, which might partially be derived from cardiac myocytes under pressure overload, may be of crucial importance in pressure overload-induced cardiac hypertrophy and cardiac dysfunction.

Complex translocation t(1;12;14)(q42;q14;q32) and HMGA2 deletion in a fetus presenting growth delay and bilateral cataracts

We report the prenatal detection of a de novo unbalanced complex chromosomal rearrangement (CCR), in a fetus with growth delay and bilateral cataracts. Standard karyotype and FISH analyses on amniotic fluid revealed a complex de novo translocation, resulting in a 46,XY,t(1;12;14)(q42;q14;q32) karyotype. CGH-array showed a significant deletion of 387  kb at 12q14.3, at a distance of only 200-700 kb from the breakpoint at 12q14, which encompassed the HMGA2 gene and occurred de novo. Although 12q14 microdeletions are associated with growth delay in several reports in the literature, we present here the smallest deletion prenatally detected, and we detail the clinical description of the fetus. The correlation between cataracts and this complex genotype is puzzling. Among the genes disrupted by the breakpoint in 12q14, GRIP1 has been associated with abnormal eye development in mice, including lens degeneration. Interestingly, HMGA2 is expressed in the mouse's developing lens, and its expression is decreased in lens of elderly humans, correlated with the severity of lens opacity. In this report, we refine the link between HMGA2 loss of function and growth delay during prenatal development. We also discuss the correlation between cataracts and genotype in this unbalanced CCR case of unexpected complexity.

MiR-186 suppresses the growth and metastasis of bladder cancer by targeting NSBP1

BACKGROUND

Increasing evidence has shown that microRNAs function as oncogenes or tumor suppressors in human malignancies, but the roles of miR-186 in human bladder cancer (BC) is still unclear.

METHODS

First, quantitative real-time PCR (qRT-PCR) was performed to detect miR-186 expression in bladder cancer tissues and cell lines. Then, Bioinformatics analysis, combined with luciferase reporter assay demonstrated the target gene of miR-186. Finally, the roles of miR-186 in regulation of tumor proliferation and invasion were further investigated.

RESULTS

Here, our study showed miR-186 was down-regulated in bladder cancer tissues and cell lines. Luciferase reporter assay showed that miR-186 targets NSBP1 3'-untranslated region (UTR) directly and suppresses NSBP1 (HMGN5) expression in human bladder cancer cells. NSBP1 siRNA- and miR-186-mediated NSBP1 knock-down experiments revealed that miR-186 suppresses cell proliferation and invasion through suppression of NSBP1 expression. Expression analysis of a set of epithelial-mesenchymal transition (EMT) markers showed that NSBP1 involves miR-186 suppressed EMT which reducing the expression of mesenchymal markers (vimentin and N-cadherin) and inducing the expression of epithelial marker (E-cadherin).

CONCLUSIONS

Our data first time identified miR-186 as the upstream regulator of NSBP1 and also suggest miR-186-suppressed NSBP1 as a novel therapeutic approach for bladder cancer.

Correlation of High Mobility Group Box-1 Protein (HMGB1) with Clinicopathological Parameters in Primary Retinoblastoma

HMGB1 is considered to be DNA chaperone as it binds without any specificity. It is the structural protein which alters nuclear homeostasis and genomic stability of chromatin. Its role in retinoblastoma (Rb) remains unclear. The aim of the present study was to evaluate the expression of HMGB1 protein in primary enucleated retinoblastomas. Expression of HMGB1 in 69 prospective cases of primary retinoblastoma were assessed by immunohistochemistry and reverse transcriptase PCR (RT-PCR) technique and correlated with clinicopathological parameters. Immunohistochemical staining revealed expression of HMGB1 in 55.07 % (38/69) cases. Semi-quantitative RT-PCR was performed on 31 fresh tumor tissues. mRNA expression was observed in 77.41 % (24/31) cases. Expression of HMGB1 was statistically significant with poor tumor differentiation (p = 0.0440) & optic nerve invasion (p = 0.0128). HMGB1 expression was frequently seen in poorly differentiated tumors and those with histopathological high risk factors. Therefore, HMGB1 may contribute to tumor invasiveness and could serve as a poor prognostic marker in Rb.

Axonal amphoterin mRNA is regulated by translational control and enhances axon outgrowth

High mobility group (HMG) proteins concentrate in the nucleus, interacting with chromatin. Amphoterin is an HMG protein (HMGB1) that has been shown to have extranuclear functions and can be secreted from some cell types. Exogenous amphoterin can increase neurite growth, suggesting that the secreted protein may have growth promoting activities in neurons. Consistent with this, we show that depletion of amphoterin mRNA from cultured adult rat DRG neurons attenuates neurite outgrowth, pointing to autocrine or paracrine mechanisms for its growth-promoting effects. The mRNA encoding amphoterin localizes to axonal processes and we showed recently that its 3'-UTR is sufficient for axonal localization of heterologous transcripts (Donnelly et al., 2013). Here, we show that amphoterin mRNA is transported constitutively into axons of adult DRG neurons. A preconditioning nerve injury increases the levels of amphoterin protein in axons without a corresponding increase in amphoterin mRNA in the axons. A 60 nucleotide region of the amphoterin mRNA 3'-UTR is necessary and sufficient for its localization into axons of cultured sensory neurons. Amphoterin mRNA 3'-UTR is also sufficient for axonal localization in distal axons of DRG neurons in vivo. Overexpression of axonally targeted amphoterin mRNA increases axon outgrowth in cultured sensory neurons, but axon growth is not affected when the overexpressed mRNA is restricted to the cell body.

Emerging roles for HMGB1 protein in immunity, inflammation, and cancer

High-mobility group box 1 (HMGB1) protein is a member of the highly conserved non-histone DNA binding protein family. First identified in 1973, as one of a group of chromatin-associated proteins with high acidic and basic amino acid content, it was so named for its characteristic rapid mobility in polyacrylamide gel electrophoresis. HMGB1 was later discovered to have another function. It is released from a variety of cells into the extracellular milieu to act on specific cell-surface receptors. In this latter role, HMGB1 is a proinflammatory cytokine that may contribute to many inflammatory diseases, including sepsis. Therefore, HMGB1 regulates intracellular cascades influencing immune cell functions, including chemotaxis and immune modulation. The bioactivity of the HMGB1 is determined by specific posttranslational modifications that regulate its role in inflammation and immunity. During tumor development, HMGB1 has been reported to play paradoxical roles in promoting both cell survival and death by regulating multiple signaling pathways. In this review, we focus on the role of HMGB1 in physiological and pathological responses, as well as the mechanisms by which it contributes to immunity, inflammation, and cancer progression.

Let-7a inhibits migration, invasion and epithelial-mesenchymal transition by targeting HMGA2 in nasopharyngeal carcinoma

BACKGROUND

Let-7a has been shown to play important roles in nasopharyngeal carcinoma (NPC) cell proliferation and apoptosis, but little is known about the function and mechanism of let-7a in nasopharyngeal carcinoma metastasis. We aimed to investigate the function and mechanism of let-7a in nasopharyngeal carcinoma metastasis and clarified the regulation of high mobility group A2 (HMGA2) by let-7a.

METHODS

The expression levels of let-7a and HMGA2 were examined in NPC clinical specimens using quantitative reverse transcription-PCR (RT-qPCR). HMGA2 was confirmed as a target of let-7a through luciferase reporter assays, RT-qPCR, and Western blotting. Furthermore, the roles of let-7a and HMGA2 in regulating NPC cells biological properties including proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) process were analyzed with let-7a mimics and si-HMGA2 transfected cells.

RESULTS

Our study demonstrated that let-7a was downregulated and inversely associated with the clinical stage, T classification and N classification, and HMGA2 was upregulated and directly associated with the clinical stage and N classification in patients with NPC. Moreover, there was an inverse correlation between let-7a expression and HMGA2 expression in NPC patient. In addition, HMGA2 was negatively regulated at the posttranscriptional level by let-7a via a binding site of HMGA2-3'UTR. In addition, synthetic let-7a mimics suppressed NPC cells migration, invasion and EMT process and knockdown of HMGA2 was consistent with the effects of let-7a in NPC cells.

CONCLUSION

Let-7a directly downregulates HMGA2 protein expression, which suppress NPC cell migration, invasion and EMT process. Let-7a could serve as a potential diagnostic marker and therapeutic target for NPC.

Pharmacological manipulation of transcription factor protein-protein interactions: opportunities and obstacles

Much research on transcription factor biology and their genetic pathways has been undertaken over the last 30 years, especially in the field of developmental biology and cancer. Yet, very little is known about the molecular modalities of highly dynamic interactions between transcription factors, genomic DNA, and protein partners. Methodological breakthroughs such as RNA-seq (RNA-sequencing), ChIP-seq (chromatin immunoprecipitation sequencing), RIME (rapid immunoprecipitation mass spectrometry of endogenous proteins), and single-molecule imaging will dramatically accelerate the discovery rate of their molecular mode of action in the next few years. From a pharmacological viewpoint, conventional methods used to target transcription factor activity with molecules mimicking endogenous ligands fail to achieve high specificity and are limited by a lack of identification of new molecular targets. Protein-protein interactions are likely to represent one of the next major classes of therapeutic targets. Transcription factors, known to act mostly via protein-protein interaction, may well be at the forefront of this type of drug development. One hurdle in this field remains the difficulty to collate structural data into meaningful information for rational drug design. Another hurdle is the lack of chemical libraries meeting the structural requirements of protein-protein interaction disruption. As more attempts at modulating transcription factor activity are undertaken, valuable knowledge will be accumulated on the modality of action required to modulate transcription and how these findings can be applied to developing transcription factor drugs. Key discoveries will spawn into new therapeutic approaches not only as anticancer targets but also for other indications, such as those with an inflammatory component including neurodegenerative disorders, diabetes, and chronic liver and kidney diseases.

Structure-specific nucleic acid recognition by L-motifs and their diverse roles in expression and regulation of the genome

The high-mobility group (HMG) domain containing proteins regulate transcription, DNA replication and recombination. They adopt L-shaped folds and are structure-specific DNA binding motifs. Here, I define the L-motif super-family that consists of DNA-binding HMG-box proteins and the L-motif of the histone mRNA binding domain of stem-loop binding protein (SLBP). The SLBP L-motif and HMG-box domains adopt similar L-shaped folds with three α-helices and two or three small hydrophobic cores that stabilize the overall fold, but have very different and distinct modes of nucleic acid recognition. A comparison of the structure, dynamics, protein-protein and nucleic acid interactions, and regulation by PTMs of the SLBP and the HMG-box L-motifs reveals the versatile and diverse modes by which L-motifs utilize their surfaces for structure-specific recognition of nucleic acids to regulate gene expression.

Chorion genes: a landscape of their evolution, structure, and regulation

Differential regulation at the level of transcription provides a means for controlling gene expression in eukaryotes, especially during development. Insect model systems have been extensively used to decipher the molecular basis of such regulatory cascades, and one of the oldest such model systems is the regulation of chorion gene expression during ovarian follicle maturation. Recent experimental and technological advances have shed new light onto the system, allowing us to revisit it. Thus, in this review we try to summarize almost 40 years' worth of studies on chorion gene regulation while-by comparing Bombyx mori and Drosophila melanogaster models-attempting to present a comprehensive, unified model of the various regulatory aspects of choriogenesis that takes into account the evolutionary conservation and divergence of the underlying mechanisms.

Expression of oncogenic HMGN5 increases the sensitivity of prostate cancer cells to gemcitabine

Prostate cancer is a leading cause of cancer-related death among men. Early diagnosis and treatment are successful against prostate cancer, yet the clinical treatment of advanced prostate cancer remains a challenge. Gemcitabine is used to treat a broad spectrum of solid tumors; however, the clinical response of prostate cancer patients to gemcitabine is limited. In the present study, we showed that HMGN5, a nucleosome binding protein that can unfold chromatin by binding to histone (H1), is overexpressed in prostate cancer cells and plays an oncogenic role in prostate cancer tumorigenesis and development by activating the MAPK signaling pathway. We also found that sensitivity of prostate cancer cells to gemcitabine was positively correlated with HMGN5 expression. Knockdown of HMGN5 expression reduced the sensitivity of PC-3 cells to gemcitabine, and ectopic HMGN5 expression in DU145 cells enhanced the sensitivity to gemcitabine. Gemcitabine decreased HMGN5 expression, consequently leading to inactivation of the MAPK signaling pathway and cleavage of the PARP protein. Finally, we showed that PC-3 cells acquire gemcitabine resistance by gradual loss of HMGN5 expression. The present study suggests that HMGN5 is a potential biomarker for treating prostate cancer, and patients with a high level HMGN5 will benefit from gemcitabine treatment.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.

The Alarmin HMGN1 contributes to antitumor immunity and is a potent immunoadjuvant

Alarmins are endogenous mediators that are elicited rapidly in response to danger signals, enhancing innate and adaptive immune responses by promoting the recruitment and maturation of antigen-presenting cells (APC). The nucleosome-binding protein HMGN1 is a potent alarmin that binds TLR4 and induces antigen-specific Th1 immune responses, but its contributions to antitumor immunity have not been explored. We found that ovalbumin (OVA)-expressing EG7 mouse thymoma cells grew much faster in Hmgn1-deficient mice than littermate-matched controls. Tumor-bearing Hmgn1(-/-) mice generated fewer OVA-specific CD8 cells in the spleen than EG7-bearing Hmgn1(+/+) mice, suggesting that HMGN1 supported T cell-mediated antitumor immunity. In addition, EG7 tumors expressing HMGN1 grew more slowly than control EG7 tumors, suggesting greater resistance to HMGN1-expressing tumors. This resistance relied on T cell-mediated immunity because it was abolished by in vivo depletion of CD4(+) and CD8(+) T cells. Moreover, mice vaccinated with a DNA vector expressing an HMGN1-gp100 fusion protein manifested gp100-specific, Th1-polarized immune responses, acquiring resistance to challenge with mouse B16F1 melanoma. Overall, our findings show that HMGN1 contributes to antitumor immunity and it may offer an effective adjuvant to heighten responses to cancer vaccines.

The high-mobility group nucleosome-binding domain 5 is highly expressed in breast cancer and promotes the proliferation and invasion of breast cancer cells

The high-mobility group nucleosome-binding domain 5 (HMGN5) is a member of the high-mobility group proteins family. Previous study found that HMGN5 is required for tumorigenesis in vitro, and aberrations in the expression of HMGN5 were found in human osteosarcoma, prostate cancer, and squamous cell carcinoma. Nevertheless, the role of HMGN5 in breast cancer remains unclear. This study aimed to investigate the expression and clinical significance of HMGN5 in human breast cancer, confirm the oncogenic role of HMGN5, and explore the mechanism by which HMGN5 contributes to invasion and metastasis. HMGN5 expression was detected in breast cancer tissues and corresponding adjacent non-cancerous tissues from 43 patients by immunohistochemistry, and the clinicopathologic characteristics of all patients were also analyzed. Next, knockdown of HMGN5 protein in MDA-MB-231 cells was performed through a small interfering RNA (siRNA) technique, and cell viability, apoptosis, and invasion were detected by cell vitality test, flow cytometry, and transwell assay, respectively. Immunohistostaining showed that HMGN5 were highly expressed in the nucleus in all breast cancer tissues as compared with the adjacent non-cancerous tissues (ANCT;(73.5 ± 11 vs. 31.0 ± 5 %, P < 0.01). HMGN5 expression level was associated with the poorly differentiated tumor cells, lymph node involvement tumor, and T4 staging tumor. Knockdown of HMGN5 inhibited cell growth, suppressed invasion, and increased cell apoptosis in human breast cancer MDA-MB-231 cells. Western blot analysis demonstrated that the expressions of PCNA, connective tissue growth factor (CTGF), and MMP-9 were decreased in human breast MDA-MB-231 cells depleted of HMGN5. In addition, the apoptotic markers (cleaved PARP and cleaved caspase-3) were significantly increased by HMGN5 knockdown, but microtubule-associated protein 1 light chain 3-II/I (LC3-II/I) did not alter. HMGN5 plays an oncogenic role in human breast cancer by inhibiting cell proliferation and invasion, and activating apoptosis, which could be exploited as a target for therapy in human breast cancer.

How the proteome packages the genome for cardiovascular development

The devastating impact of congenital heart defects has made mechanisms of vertebrate heart and vascular development an active area of study. Because myocyte death is a common feature of acquired cardiovascular diseases and the adult heart does not regenerate, the need exists to understand whether features of the developing heart and vasculature-which are more plastic-can be exploited therapeutically in the disease setting. We know that a core network of transcription factors governs commitment to the cardiovascular lineage, and recent studies using genetic loss-of-function approaches and unbiased genomic studies have revealed the role for various chromatin modulatory events. We reason that chromatin structure itself is a causal feature that influences transcriptome complexity along a developmental continuum, and the purpose of this article is to highlight the areas in which 'omics technologies have the potential to reveal new principles of phenotypic plasticity in development. We review the major mechanisms of chromatin structural regulation, highlighting what is known about their actions to control cardiovascular differentiation. We discuss emergent mechanisms of regulation that have been identified on the basis of genomic and proteomic studies of cardiac nuclei and identify current challenges to an integrated understanding of chromatin structure and cardiovascular phenotype.

An in vitro study on the effect of vinca alkaloid, vinorelbine, on chromatin histone, HMGB proteins and induction of apoptosis in mice non-adherent bone marrow cells

CONTEXT

Vinoreline is a vinca alkaloid anticancer drug widely used in cancer therapy. Drugs are not target specific, therefore might affect normal tissues/cells, in which bone marrow is the important one.

OBJECTIVE

To elucidate the cytotoxic and genotoxic effect of vinca alkaloid anti cancer drug, vinorelbine, on mice non-adherent bone marrow cells in vitro.

MATERIALS AND METHODS

Non-adherent bone marrow cells were isolated and exposed to various concentrations (0-160 µg/ml) for 4 h at 23 °C. The chromatin proteins were analyzed by SDS PAGE and western blot. Fluorescent dye staining of the cells, anion superoxide and DNA fragmentations assays were also employed.

RESULT

The results from MTT and trypan blue exclusion assays represented reduction of the cells viability. Extractability of histones and HMG proteins contrasted with difficulty as their content was decreased on SDS-gel upon increasing drug concentration as western blots confirmed it. The amount of degradation form of PARP (89 KD) increased significantly in a dose dependent manner. Increase in anion superoxide production and DNA fragmentation together with cytological detection of chromatin condensation and cellular damage upon exposure of the cells to vinorelbine were indicative of apoptosis induction in these normal cells.

CONCLUSION

Vinorelbine is genotoxic in non-adherent bone marrow cells as affects chromatin components, DNA, histone and HMGB1 proteins and induces apoptosis.

Chromatin maintenance and dynamics in senescence: a spotlight on SAHF formation and the epigenome of senescent cells

Senescence is a stable proliferation arrest characterized by profound changes in cellular morphology and metabolism as well as by extensive chromatin reorganization in the nucleus. One particular hallmark of chromatin changes during senescence is the formation of punctate DNA foci in DAPI-stained senescent cells that have been called senescence-associated heterochromatin foci (SAHF). While many advances have been made concerning our understanding of the effectors of senescence, how chromatin is reorganized and maintained in senescent cells has remained largely elusive. Because chromatin structure is inherently dynamic, senescent cells face the challenge of developing chromatin maintenance mechanisms in the absence of DNA replication in order to maintain the senescent phenotype. Here, we summarize and review recent findings shedding light on SAHF composition and formation via spatial repositioning of chromatin, with a specific focus on the role of lamin B1 for this process. In addition, we discuss the physiological implication of SAHF formation, the role of histone variants, and histone chaperones during senescence and also elaborate on the more general changes observed in the epigenome of the senescent cells.

A polymorphism of HMGA1 is associated with increased risk of metabolic syndrome and related components

The metabolic syndrome (MetS) is a common disorder, where systemic insulin-resistance is associated with increased risk for type 2 diabetes (T2D) and cardiovascular disease. Identifying genetic traits influencing risk and progression of MetS is important. We and others previously reported a functional HMGA1 gene variant, rs146052672, predisposing to T2D. Here we investigated the association of rs146052672 variant with MetS and related components. In a case-control study from Italy and Turkey, increased risk of MetS was seen among carriers of the HMGA1 variant. In the larger Italian cohort, this variant positively correlated with BMI, hyperglycemia and insulin-resistance, and negatively correlated with serum HDL-cholesterol. Association between rs146052672 variant and MetS occurred independently of T2D, indicating that HMGA1 gene defects play a pathogenetic role in MetS and other insulin-resistance-related conditions. Overall, our results indicate that the rs146052672 variant represents an early predictive marker of MetS, as well as a predictive tool for therapy.

Proliferation potential of Müller glia after retinal damage varies between mouse strains

Retinal Müller glia can serve as a source for regeneration of damaged retinal neurons in fish, birds and mammals. However, the proliferation rate of Müller glia has been reported to be low in the mammalian retina. To overcome this problem, growth factors and morphogens have been studied as potent promoters of Müller glial proliferation, but the molecular mechanisms that limit the proliferation of Müller glia in the mammalian retina remain unknown. In the present study, we found that the degree of damage-induced Müller glia proliferation varies across mouse strains. In mouse line 129×1/SvJ (129), there was a significantly larger proliferative response compared with that observed in C57BL/6 (B6) after photoreceptor cell death. Treatment with a Glycogen synthase kinase 3 (GSK3) inhibitor enhanced the proliferation of Müller glia in 129 but not in B6 mouse retinas. We therefore focused on the different gene expression patterns during retinal degeneration between B6 and 129. Expression levels of Cyclin D1 and Nestin correlated with the degree of Müller glial proliferation. A comparison of genome-wide gene expression between B6 and 129 showed that distinct sets of genes were upregulated in the retinas after damage, including immune response genes and chromatin remodeling factors.

HMGA proteins as modulators of chromatin structure during transcriptional activation

High mobility group (HMG) proteins are the most abundant non-histone chromatin associated proteins. HMG proteins bind to DNA and nucleosome and alter the structure of chromatin locally and globally. Accessibility to DNA within chromatin is a central factor that affects DNA-dependent nuclear processes, such as transcription, replication, recombination, and repair. HMG proteins associate with different multi-protein complexes to regulate these processes by mediating accessibility to DNA. HMG proteins can be subdivided into three families: HMGA, HMGB, and HMGN. In this review, we will focus on recent advances in understanding the function of HMGA family members, specifically their role in gene transcription regulation during development and cancer.

Environmental signaling through the mechanistic target of rapamycin complex 1: mTORC1 goes nuclear

Mechanistic target of rapamycin complex 1 (mTORC1) is a well-known regulator of cell growth and proliferation in response to environmental stimuli and stressors. To date, the majority of mTORC1 studies have focused on its function as a cytoplasmic effector of translation regulation. However, recent studies have identified additional, nuclear-specific roles for mTORC1 signaling related to transcription of the ribosomal DNA (rDNA) and ribosomal protein (RP) genes, mitotic cell cycle control, and the regulation of epigenetic processes. As this area of study is still in its infancy, the purpose of this review to highlight these significant findings and discuss the relevance of nuclear mTORC1 signaling dysregulation as it pertains to health and disease.

Abundant expression of HMGB1 in human T-cell lymphotropic virus type I-infected T-cell lines and high plasma levels of HMGB1 in patients with adult T-cell leukemia

High mobility group box 1 (HMGB1) functions as a chromatin-associated nuclear protein and an extracellular signaling molecule. The concentration of HMGB1 protein and the expression of HMGB1 mRNA were analyzed by ELISA and polymerase chain reaction (PCR), respectively. The present study reports high plasma HMGB1 levels in patients with adult T-cell leukemia [ATL; which is caused by infection with human T-cell lymphotropic virus type I (HTLV-I)] compared with normal controls. In addition, HMGB1 was highly expressed in HTLV-I-infected T-cell lines compared with uninfected T-cell lines. The HTLV-I oncoprotein, Tax, induced extracellular release of HMGB1 in T cells. The results suggest that HMGB1 is a potential biomarker and a therapeutic target for ATL.

The chromatin architectural proteins HMGD1 and H1 bind reciprocally and have opposite effects on chromatin structure and gene regulation

BACKGROUND

Chromatin architectural proteins interact with nucleosomes to modulate chromatin accessibility and higher-order chromatin structure. While these proteins are almost certainly important for gene regulation they have been studied far less than the core histone proteins.

RESULTS

Here we describe the genomic distributions and functional roles of two chromatin architectural proteins: histone H1 and the high mobility group protein HMGD1 in Drosophila S2 cells. Using ChIP-seq, biochemical and gene specific approaches, we find that HMGD1 binds to highly accessible regulatory chromatin and active promoters. In contrast, H1 is primarily associated with heterochromatic regions marked with repressive histone marks. We find that the ratio of HMGD1 to H1 binding is a better predictor of gene activity than either protein by itself, which suggests that reciprocal binding between these proteins is important for gene regulation. Using knockdown experiments, we show that HMGD1 and H1 affect the occupancy of the other protein, change nucleosome repeat length and modulate gene expression.

CONCLUSION

Collectively, our data suggest that dynamic and mutually exclusive binding of H1 and HMGD1 to nucleosomes and their linker sequences may control the fluid chromatin structure that is required for transcriptional regulation. This study provides a framework to further study the interplay between chromatin architectural proteins and epigenetics in gene regulation.

Current hypotheses on the mechanisms of alcoholism

Chronic use of alcohol results in progressive changes to brain and behavior that often lead to the development of alcohol dependence and alcoholism. Although the mechanisms underlying the development of alcoholism remain to be fully elucidated, diminished executive functioning due to hypoactive prefrontal cortex executive control and hyperactive limbic system anxiety and negative emotion might contribute mechanistically to the shift from experimental use to alcoholism and dependence. In the chapter that follows, behavioral deficits associated with cortical dysfunction and neurodegeneration will be related to the behavioral characteristics of alcoholism (e.g., diminished executive function, impulsivity, altered limbic modulation). We will provide evidence that alterations in cyclic AMP-responsive element binding protein (CREB: neurotrophic) and NF-κB (neuroimmune) signaling contribute to the development and persistence of alcoholism. In addition, genetic predispositions and an earlier age of drinking onset will be discussed as contributing factors to the development of alcohol dependence and alcoholism. Overall chronic ethanol-induced neuroimmune gene induction is proposed to alter limbic and frontal neuronal networks contributing to the development and persistence of alcoholism.

A model for the molecular underpinnings of tooth defects in Axenfeld-Rieger syndrome

Patients with Axenfeld-Rieger Syndrome (ARS) present various dental abnormalities, including hypodontia, and enamel hypoplasia. ARS is genetically associated with mutations in the PITX2 gene, which encodes one of the earliest transcription factors to initiate tooth development. Thus, Pitx2 has long been considered as an upstream regulator of the transcriptional hierarchy in early tooth development. However, because Pitx2 is also a major regulator of later stages of tooth development, especially during amelogenesis, it is unclear how mutant forms cause ARS dental anomalies. In this report, we outline the transcriptional mechanism that is defective in ARS. We demonstrate that during normal tooth development Pitx2 activates Amelogenin (Amel) expression, whose product is required for enamel formation, and that this regulation is perturbed by missense PITX2 mutations found in ARS patients. We further show that Pitx2-mediated Amel activation is controlled by chromatin-associated factor Hmgn2, and that Hmgn2 prevents Pitx2 from efficiently binding to and activating the Amel promoter. Consistent with a physiological significance to this interaction, we show that K14-Hmgn2 transgenic mice display a severe loss of Amel expression on the labial side of the lower incisors, as well as enamel hypoplasia-consistent with the human ARS phenotype. Collectively, these findings define transcriptional mechanisms involved in normal tooth development and shed light on the molecular underpinnings of the enamel defect observed in ARS patients who carry PITX2 mutations. Moreover, our findings validate the etiology of the enamel defect in a novel mouse model of ARS.

Aberrant neural stem cell proliferation and increased adult neurogenesis in mice lacking chromatin protein HMGB2

Neural stem and progenitor cells (NSCs/NPCs) are distinct groups of cells found in the mammalian central nervous system (CNS). Previously we determined that members of the High Mobility Group (HMG) B family of chromatin structural proteins modulate NSC proliferation and self-renewal. Among them HMGB2 was found to be dynamically expressed in proliferating and differentiating NSCs, suggesting that it may regulate NSC maintenance. We report now that Hmgb2(-/-) mice exhibit SVZ hyperproliferation, increased numbers of SVZ NSCs, and a trend towards aberrant increases in newly born neurons in the olfactory bulb (OB) granule cell layer. Increases in the levels of the transcription factor p21 and the Neural cell adhesion molecule (NCAM), along with down-regulation of the transcription/pluripotency factor Oct4 in the Hmgb2-/- SVZ point to a possible pathway for this increased proliferation/differentiation. Our findings suggest that HMGB2 functions as a modulator of neurogenesis in young adult mice through regulation of NSC proliferation, and identify a potential target via which CNS repair could be amplified following trauma or disease-based neuronal degeneration.

Characterization of the Stoichiometry of HMGA1/DNA Complexes

High-mobility group A1 (HMGA1) non-histone chromatin architectural transcription factors regulate gene expression, embryogenesis, cell differentiation, and adaptive immune responses by binding DNA and other transcription factors. HMGA1 has also been shown to be highly over-expressed in many human cancers and is considered to be a valuable cancer biomarker. Elevated HMGA1 expression levels also make cancer cells resistant to chemotherapy. Here, HMGA1/DNA complex formation was investigated using electrophoretic mobility shift assays (EMSA). Collectively, the EMSA results indicated that full length HMGA1 mixed with DNA containing three AT-hook binding sites formed four distinct HMGA1/DNA complexes ranging in stoichiometry from 1:2 to 3:1 in HMGA1:DNA ratio. The data indicated that the distribution of complexes with different HMGA1 to DNA stoichiometries depended on the molar ratio of HMGA1 to DNA in solution, which could have significant biological implications given that HMGA1 is highly over-expressed in human cancer cells. The two naturally occurring isoforms of HMGA1, HMGA1a and HMGA1b, the latter containing an 11 amino acid deletion between the first and second AT-hooks, were observed to have slightly different DNA binding profiles. Finally, HMGA1 binding affinity to DNA was found to be influenced by the DNA A:T segment sequence context, with higher specificity be observed in HMGA1 binding to T_nA_n segments, which have two local minor groove minima on either side of the TpA step, compared to A_n:T_n segments, which have a single minor groove minimum at the 3' end of the A_n run, implying AT-hook binding favors narrow minor groove structure.

Comparative proteomic analysis of generative and sperm cells reveals molecular characteristics associated with sperm development and function specialization

In flowering plants, two sperm cells (SCs) are generated from a generative cell (GC) in the developing pollen grain or growing pollen tube and are then delivered to the embryo sac to initiate double fertilization. SC development and function specialization involve the strict control of the protein (gene) expression program and coordination of diverse cellular processes. However, because methods for collecting a large amount of highly purified GCs and SCs for proteomic and transcriptomic studies from a plant are not available, molecular information about the program and the interconnections is lacking. Here, we describe a method for obtaining a large quantity of highly purified GCs and SCs from just-germinated lily pollen grains and growing pollen tubes for proteomic analysis. Our observation showed that SCs had less condensed chromatin and more vacuole-like structures than GCs and that mature SCs were arrested at the G2 phase. Comparison of SC and GC proteomes revealed 101 proteins differentially expressed in the two proteomes. These proteins are involved in diverse cellular and metabolic processes, with preferential involvement in metabolism, the cell cycle, signaling, the ubiquitin/proteasome pathway, and chromatin remodeling. Impressively, almost all proteins in SCF complex-mediated proteolysis and the cell cycle were up-regulated in SCs, whereas those in chromatin remodeling and stress response were down-regulated. Our data also reveal the coordination of SCF complex-mediated proteolysis, cell cycle progression, and DNA repair in SC development and function specialization. This study revealed for the first time a difference in protein profiles between GCs and SCs.

Chromatin dynamics during lytic infection with herpes simplex virus 1

Latent HSV-1 genomes are chromatinized with silencing marks. Since 2004, however, there has been an apparent inconsistency in the studies of the chromatinization of the HSV-1 genomes in lytically infected cells. Nuclease protection and chromatin immunoprecipitation assays suggested that the genomes were not regularly chromatinized, having only low histone occupancy. However, the chromatin modifications associated with transcribed and non-transcribed HSV-1 genes were those associated with active or repressed transcription, respectively. Moreover, the three critical HSV-1 transcriptional activators all had the capability to induce chromatin remodelling, and interacted with critical chromatin modifying enzymes. Depletion or overexpression of some, but not all, chromatin modifying proteins affected HSV-1 transcription, but often in unexpected manners. Since 2010, it has become clear that both cellular and HSV-1 chromatins are highly dynamic in infected cells. These dynamics reconcile the weak interactions between HSV-1 genomes and chromatin proteins, detected by nuclease protection and chromatin immunoprecipitation, with the proposed regulation of HSV-1 gene expression by chromatin, supported by the marks in the chromatin in the viral genomes and the abilities of the HSV-1 transcription activators to modulate chromatin. It also explains the sometimes unexpected results of interventions to modulate chromatin remodelling activities in infected cells.

High-mobility group box 2 is associated with prognosis of glioblastoma by promoting cell viability, invasion, and chemotherapeutic resistance

BACKGROUND

The expression profile of high-mobility group box 2 (HMGB2) in patients with glioblastoma multiforme (GBM) and its clinical signature with underlying mechanisms were not fully explored.

METHODS

HMGB2 protein levels were measured in 51 GBM patients by immunohistochemical studies. To clarify the precise role of HMGB2 on cell invasion and viability of 3 GBM cell lines, we did in vitro and in vivo analyses with lentivirus vectors and small interfering RNA. Transwell invasion assays and wound-healing assays were used to analyze the invasion of GBM cells. Expression of p53 and matrix metalloproteinase 2/tissue inhibitors of metalloproteinase 2 (MMP2/TIMP2) protein was analyzed by Western blot.

RESULTS

HMGB2 protein expression was significantly higher in GBM than in controlled brain tissues (P < .0001). HMGB2 overexpression was significantly correlated with shorter overall survival time, which was the only independent prognostic factor for overall survival in a multivariate analysis (P = .017). HMGB2 knockdown by small interfering RNA decreased cell viability and invasion in vitro and significantly decreased tumor volume in vivo, which might be involved in the change of p53 expression and the balance of MMP2/TIMP2. Moreover, silencing of HMGB2 could significantly increase the sensitivity of GBM cells to temozolomide chemotherapy.

CONCLUSIONS

Our present data suggest that HMGB2 expression is a significant prognostic factor and might play an important role in cell invasion and temozolomide-induced chemotherapeutic sensitivity of GBM. This study highlights the importance of HMGB2 as a novel prognostic marker and an attractive therapeutic target of GBM.