High-mobility group protein B1 (HMGB1) is a novel biomarker for human ovarian cancer

CircUBE2D2 regulates HMGB1 through miR-885-5p to promote ovarian cancer malignancy

BACKGROUND

The newly discovered CircUBE2D2 has been shown to abnormally upregulate and promote cancer progression in a variety of cancers. The present study explored circUBE2D2 (hsa_circ_0005728) in Ovarian Cancer (OC) progression.

METHODS

CircUBE2D2, miR-885-5p, and HMGB1 were examined by RT-qPCR or WB. SKOV-3 cell functions (including cell viability, apoptosis, migration, and invasion) were validated using the CCK-8, flow cytometry, scratch assay, and transwell assay, respectively. The direct relationship between miR-885-5p and circUBE2D2 or HMGB1 was confirmed by a dual-luciferase reporter and RNA pull-down analysis. circUBE2D2's role in vivo tumor xenograft experiment was further probed.

RESULTS

OC tissue and cell lines had higher circUBE2D2 and HMGB1 and lower miR-885-5p. Mechanically, CircUBE2D2 shared a binding relation with miR-885-5p, while miR-885-5p can directly target HMGB1. Eliminating circUBE2D2 or miR-885-5p induction inhibited OC cell activities. However, these functions were relieved by down-regulating miR-885-5p or HMGB1 induction. Furthermore, circUBE2D2 knockout reduced tumor growth.

CONCLUSION

CircUBE2D2 regulates the expression of HMGB1 by acting as a sponge of ceRNA as miR-885-5p, thereby promoting the control of OC cell proliferation and migration and inhibiting cell apoptosis. Targeting CircUBE2D2 could serve as a new potential treatment strategy for OC.

Targeting tumour markers in ovarian cancer treatment

Ovarian cancers (OC) are the most common, lethal, and stage-dependent cancers at the global level, specifically in female patients. Targeted therapies involve the administration of drugs that specifically target the alterations in tumour cells responsible for their growth, proliferation, and metastasis, with the aim of treating particular patients. Presently, within the realm of gynaecological malignancies, specifically in breast and OCs, there exist various prospective therapeutic targets encompassing tumour-intrinsic signalling pathways, angiogenesis, homologous-recombination deficit, hormone receptors, and immunologic components. Breast cancers are often detected in advanced stages, primarily due to the lack of a reliable screening method. However, various tumour markers have been extensively researched and employed to evaluate the condition, progression, and effectiveness of medication treatments for this ailment. The emergence of recent technological advancements in the domains of bioinformatics, genomics, proteomics, and metabolomics has facilitated the exploration and identification of hitherto unknown biomarkers. The primary objective of this comprehensive review is to meticulously investigate and analyze both established and emerging methodologies employed in the identification of tumour markers associated with OC.

Systematic identification of key extracellular proteins as the potential biomarkers in lupus nephritis

Background

Lupus nephritis (LN) is the most common and severe clinical manifestation of systemic lupus erythematosus (SLE) with considerable morbidity/mortality and limited treatment options. Since kidney biopsy is a relative hysteretic indicator, it is indispensable to investigate potential biomarkers for early diagnosis and predicting clinical outcomes of LN patients. Extracellular proteins may become the promising biomarkers by the secretion into body fluid. Our study linked extracellular proteins with lupus nephritis to identify the emerging biomarkers.

Methods

The expression profiling data were acquired from the Gene Expression Omnibus (GEO) database. Meanwhile, the two gene lists encoding extracellular proteins were collected from the Human Protein Atlas (HPA) and UniProt database. Subsequently, the extracellular protein-differentially expressed genes (EP-DEGs) were screened out, and the key EP-DEGs were determined by MCODE, MCC, and Degree methods via the protein–protein interaction (PPI) network. The expression level, immune characteristics, and diagnostic value of these candidate biomarkers were investigated. Finally, the Nephroseq V5 tool was applied to evaluate the clinical significance of the key EP-DEGs.

Results

A total of 164 DEGs were acquired by comparing LN samples with healthy controls based on GSE32591 datasets. Then, 38 EP-DEGs were screened out through the intersection between DEGs and extracellular protein gene lists. Function enrichment analysis indicated that these EP-DEGs might participate in immune response and constitute the extracellular matrix. Four key EP-DEGs (LUM, TGFBI, COL1A2, and POSTN) were eventually identified as candidate biomarkers, and they were all overexpressed in LN samples. Except that LUM expression was negatively correlated with most of the immune regulatory genes, there was a positive correlation between the remaining three biomarkers and the immune regulatory genes. In addition, these biomarkers had high diagnostic value, especially the AUC value of the LUM–TGFBI combination which reached almost 1 (AUC = 0.973), demonstrating high accuracy in distinguishing LN from controls. Finally, we found a meaningful correlation of these biomarkers with sex, WHO class, and renal function such as glomerular filtration rate (GFR), serum creatinine level, and proteinuria.

Conclusion

In summary, our study comprehensively identified four key EP-DEGs exerting a vital role in LN diagnosis and pathogenesis and serving as promising therapeutic targets.

Observation of the cervical microbiome in the progression of cervical intraepithelial neoplasia

OBJECTIVE

Cervical microbial community in the cervical intraepithelial neoplasia and cervical cancer patients was analysed to study its composition, diversity and signalling pathways by high-throughput 16S rDNA sequencing,and the candidate genes associated with occurrence and progression of cervical intraepithelial neoplasia were screened out and the model was established to predict the evolution of cervical intraepithelial neoplasia malignant transformation from the cervical microbial genes aspect.

METHODS

Cervical tissues of normal, cervical intraepithelial neoplasia and cervical cancer patients without receiving any treatment were collected. The correlation between candidate genes and cervical intraepithelial neoplasia progression was initially determined by analyzing the microbial flora. Real-time fluorescence quantitative PCR was used to detect the expression of candidate genes in different cervical tissues, ROC curve and logistic regression was used to analyse and predict the risk factors related to the occurrence and progression of cervical intraepithelial neoplasia. Finally, the early warning model of cervical intraepithelial neoplasia occurrence and progression is established.

RESULTS

Cervical tissues from normal, cervical intraepithelial neoplasia and cervical cancer patients were collected for microbial community high-throughput 16S rDNA sequencing. The analysis revealed five different pathways related to cervical intraepithelial neoplasia. 10 candidate genes were selected by further bioinformatics analysis and preliminary screening. Real time PCR, ROC curve and Logistic regression analysis showed that human papillomavirus infection, TCT severity, ABCG2, TDG, PCNA were independent risk factors for cervical intraepithelial neoplasia. We used these indicators to establish a random forest model. Seven models were built through different combinations. The model 4 (ABCG2 + PCNA + TDG) was the best early warning model for the occurrence and progression of CIN.

CONCLUSIONS

A total of 5 differential pathways and 10 candidate genes related to occurrence and progression of cervical intraepithelial neoplasia were found in cervical microbial community. This study firstly identified the genes from cervical microbial community that play an important role in the occurrence and progression of cervical intraepithelial neoplasia. At the same time, the early warning model including ABCG2 + PCNA+TDG genes provided a new idea and target for clinical prediction and blocking the evolution of cervical intraepithelial neoplasia malignant transformation from the aspect of cervical microbiological related genes.

The HMGB1-2 Ovarian Cancer Interactome. The Role of HMGB Proteins and Their Interacting Partners MIEN1 and NOP53 in Ovary Cancer and Drug-Response

High mobility group box B (HMGB) proteins are overexpressed in different types of cancers such as epithelial ovarian cancers (EOC). We have determined the first interactome of HMGB1 and HMGB2 in epithelial ovarian cancer (the EOC-HMGB interactome). Libraries from the SKOV-3 cell line and a primary transitional cell carcinoma (TCC) ovarian tumor were tested by the Yeast Two Hybrid (Y2H) approach. The interactome reveals proteins that are related to cancer hallmarks and their expression is altered in EOC. Moreover, some of these proteins have been associated to survival and prognosis of patients. The interaction of MIEN1 and NOP53 with HMGB2 has been validated by co-immunoprecipitation in SKOV-3 and PEO1 cell lines. SKOV-3 cells were treated with different anti-tumoral drugs to evaluate changes in HMGB1, HMGB2, MIEN1 and NOP53 gene expression. Results show that combined treatment of paclitaxel and carboplatin induces a stronger down-regulation of these genes in comparison to individual treatments. Individual treatment with paclitaxel or olaparib up-regulates NOP53, which is expressed at lower levels in EOC than in non-cancerous cells. On the other hand, bevacizumab diminishes the expression of HMGB2 and NOP53. This study also shows that silencing of these genes affects cell-viability after drug exposure. HMGB1 silencing causes loss of response to paclitaxel, whereas silencing of HMGB2 slightly increases sensitivity to olaparib. Silencing of either HMGB1 or HMGB2 increases sensitivity to carboplatin. Lastly, a moderate loss of response to bevacizumab is observed when NOP53 is silenced.

HMGB1 protein as a novel target for cancer

Highly conserved nuclear protein High Mobility Group Box1 (HMGB1) present in mammals has functionality as an immuno-modulator in the form of cytokine molecule, as a nuclear factor to regulate these molecules and DNA structural determination. It has proximal homologous DNA binding domains Box-A, Box-B and distal C-terminal domain. Reduced form exists in basic condition has chemotaxis activity, while form with disulphide bond reduced at 106th cysteine showed cytokine activity. The oxidized form is devoid of both activities. HMGB1 binds and bends dsDNA and also activates genes for secretion of inflammatory cytokines such as IL-1β, TNF-α, IL-6 and IL-18. It can interact with transcription factors Rel/NF-κB and p53 responsible for up-regulating oncogenes. Oxidative stressed injured tissues actively secrete HMGB1 outside cells to necrotize other nearby tissues passively in cytosol. Acetylation of HMGB1 weakens its binding with DNA, and promotes its migration to different tissues leading to secretion of inflammatory-cytokines. HMGB1 expression has been found very important in the genesis and promotion of different cancer by promoting metastasis. In current article, we emphasized on condition based structural variability of HMGB1, mechanism of release, physiological functions and its functionality as a biomarker for cancer to be targeted to curb cancer genesis and progression.

Delineating the HMGB1 and HMGB2 interactome in prostate and ovary epithelial cells and its relationship with cancer

High Mobility Group B (HMGB) proteins are involved in cancer progression and in cellular responses to platinum compounds used in the chemotherapy of prostate and ovary cancer. Here we use affinity purification coupled to mass spectrometry (MS) and yeast two-hybrid (Y2H) screening to carry out an exhaustive study of HMGB1 and HMGB2 protein interactions in the context of prostate and ovary epithelia. We present a proteomic study of HMGB1 partners based on immunoprecipitation of HMGB1 from a non-cancerous prostate epithelial cell line. In addition, HMGB1 and HMGB2 were used as baits in yeast two-hybrid screening of libraries from prostate and ovary epithelial cell lines as well as from healthy ovary tissue. HMGB1 interacts with many nuclear proteins that control gene expression, but also with proteins that form part of the cytoskeleton, cell-adhesion structures and others involved in intracellular protein translocation, cellular migration, secretion, apoptosis and cell survival. HMGB2 interacts with proteins involved in apoptosis, cell motility and cellular proliferation. High confidence interactors, based on repeated identification in different cell types or in both MS and Y2H approaches, are discussed in relation to cancer. This study represents a useful resource for detailed investigation of the role of HMGB1 in cancer of epithelial origins, as well as potential alternative avenues of therapeutic intervention.

Expression of pAkt is associated with a poor prognosis in Chinese women with invasive ductal breast cancer

Over the past three decades, numerous patients with breast cancer succumbed to cancer metastasis and recurrence, while, the exact mechanisms underlying this malignancy, and the potential biomarkers for prognosis prediction remain elusive. It was previously demonstrated that phosphorylated RAC-α serine/threonine-protein kinase (pAkt) and Beclin 1 was associated with cancer metastasis, and recurrence. Thus far, the expression patterns of pAkt and Beclin 1 in breast cancer tissues, and their associations with the prognosis of invasive ductal breast cancer remain inconclusive, which may be due to various factors, including ethnicity and pathological types. In the present study, a total of 90 Chinese female patients with invasive ductal breast cancer between June 1999 and August 2002 were enrolled at Shanghai First People's Hospital (Shanghai, China). The patients were followed up from 5 months to 13.5 years for survival analysis. The expressional levels of pAkt and Beclin 1 in invasive ductal breast cancer tissues, and the normal paracancerous tissues were measured by immunohistochemistry. Associations with prognosis following surgery were further evaluated using Cox regression analysis. In 90 invasive ductal breast cancer samples, pAkt was detected in 17 (18.9%) samples and Beclin 1 in 33 (36.7%) samples, but both were not detected in any of the paracancerous samples. Survival analysis revealed that pAkt expression carried a tendency to predict a shorter disease-free survival (DFS) in patients with invasive ductal breast cancer. Additionally, Beclin 1 expression was not significantly associated with survival. Furthermore, univariate Cox regression analysis demonstrated that pAkt expression was negatively associated with DFS and overall survival. Multivariate Cox regression analysis indicated that pAkt expression was an independent risk factor associated with poor prognosis in patients with invasive ductal breast cancer (all P<0.05). pAkt may be used as a potential prognostic biomarker in Chinese women with invasive ductal breast cancer.

The association of HMGB1 expression with clinicopathological significance and prognosis in Asian patients with colorectal carcinoma: a meta-analysis and literature review

Background

The association of high mobility group box 1 (HMGB1) expression with clinicopathological significance and prognosis in Asian patients with colorectal carcinoma (CRC) remains controversial. The purpose of this study was to conduct a meta-analysis and literature review to identify the role of HMGB1 in the development and prognosis of CRC in Asians.

Methods

All eligible studies regarding the association between HMGB1 expression in tissue with clinicopathological significance and prognosis in Asian patients with CRC published up to January 2015 were identified by searching PubMed, Web of Science, Chinese National Knowledge Infrastructure, and WanFang database. Analysis of pooled data was performed, while odds ratio (OR) or hazard radio with 95% confidence interval (CI) was calculated and summarized to evaluate the strength of this association in fixed- or random-effects model.

Results

The expression level of HMGB1 in CRC tissues was much higher than normal colorectal tissues (OR =27.35, 95% CI 9.32–80.26, P<0.0001) and para-tumor colorectal tissues (OR =10.06, 95% CI 4.61–21.95, P<0.0001). There was no relation between the HMGB1 expression and sex, age, clinical T stage, tumor size, and location (colon or rectum cancer). However, a significant relation was detected between the HMGB1 expression and clinical stage (American Joint Committee on Cancer 7), lymph node metastasis, distant metastasis, tumor invasion depth, and differentiation rate (P=0.002, P≤0.0001, P<0.0001, P<0.0001, and P=0.007, respectively). Patients with higher HMGB1 expression had shorter overall survival time, whereas patients with lower level of HMGB1 had better survival (hazard ratio =1.40, 95% CI 0.98–1.82, P<0.0001).

Conclusion

In this meta-analysis, our results illustrated the significant relationship of HMGB1 protein overexpression in tissues with clinicopathological characteristics and prognosis of CRC. Thus, HMGB1 may be a promising marker in predicting the clinical outcome of patients with CRC. However, more well-designed studies of large sample size are warranted to validate the findings of current study.

High Mobility Group B Proteins, Their Partners, and Other Redox Sensors in Ovarian and Prostate Cancer

Cancer cells try to avoid the overproduction of reactive oxygen species by metabolic rearrangements. These cells also develop specific strategies to increase ROS resistance and to express the enzymatic activities necessary for ROS detoxification. Oxidative stress produces DNA damage and also induces responses, which could help the cell to restore the initial equilibrium. But if this is not possible, oxidative stress finally activates signals that will lead to cell death. High mobility group B (HMGB) proteins have been previously related to the onset and progressions of cancers of different origins. The protein HMGB1 behaves as a redox sensor and its structural changes, which are conditioned by the oxidative environment, are associated with different functions of the protein. This review describes recent advances in the role of human HMGB proteins and other proteins interacting with them, in cancerous processes related to oxidative stress, with special reference to ovarian and prostate cancer. Their participation in the molecular mechanisms of resistance to cisplatin, a drug commonly used in chemotherapy, is also revised.

Expression of high mobility group box 1 protein predicts a poorer prognosis for patients with osteosarcoma

The high mobility group box 1 (HMGB1) protein functions as an extracellular signaling molecule that is critical in inflammation and carcinogenesis. The HMGB1 protein is actively secreted by natural killer cells, monocytes and macrophages, and acts as an inflammatory cytokine. The present study enrolled 174 patients that underwent a tumorectomy between 2006 and 2013 in Shandong Provincial Hospital. The age of the patients ranged between 13 and 74 years, with a median age of 27 years. The tumors of the patients were staged according to the Union for International Cancer Control 2009 tumor-node-metastasis tumor staging system. Nuclear grading was based on the Fuhrman grading system. In the osteosarcoma tissue samples, HMGB1 expression was detected in 84 samples (48.3%) with a low immunoreactivity and in 90 samples (51.7%) with a high immunoreactivity. The association between clinicopathological characteristics and tumor cell HMGB1 expression (low vs. high) was summarized. The association between HMGB1 expression and tumor size, tumor stage and nuclear grade was statistically significant (P=0.034, 0.008 and 0.019, respectively). There was no significant association between HMGB1 expression and the age of the patients (P=0.335; Table I). The current study demonstrated that patients with a high HMGB1 expression (>50% cells expressing HMGB1) had poorer survival rates, and therefore a poorer prognosis, compared with patients with low HMGB1 immunostaining (10-50% cells expressing HMGB1). The results of the present study suggest that higher expression levels of HMGB1 are significantly associated with a poorer prognosis and may act as a marker for prognosis in osteosarcoma, particularly osteosarcoma recurrence. Additional studies investigating the biological features of HMGB1 may confirm the potential role of HMGB1 as a novel target for anticancer therapy in osteosarcoma.

Clinical impact of high mobility group box 1 protein in epithelial ovarian cancer

PURPOSE

The aim of this study was to confirm the expression of high mobility group box 1 (HMGB1) in patients with epithelial ovarian cancer (EOC) and to evaluate the prognostic significance of HMGB1.

METHODS

A total of 74 patients with EOC comprised our cohort. Retrospectively collected tissue microarray from EOC patients treated with debulking surgery followed by taxane and platinum chemotherapy were analyzed for evaluation of the prognostic significance of HMGB1. Expression of HMGB1 was assessed by immunohistochemistry.

RESULTS

The positive staining was detected in 80% of EOC patients and the rate of high HMGB1 expression was 42%. In advanced stage, patients with high HMGB1 expression showed a poorer prognosis than low HMGB1 expression group [median progression-free survival (PFS), 10.8 vs. 21.7 months, P = 0.005]. High HMGB1 expression was an independent predictor for PFS (P = 0.024).

CONCLUSIONS

HMGB1 expression is expected as a promising biomarker for EOC and further studies are needed to assess potential roles in EOC.

The microRNA-325 inhibits hepatocellular carcinoma progression by targeting high mobility group box 1

Background

MicroRNAs (miRNAs) can serve as tumor suppressors and might provide an efficient strategy for annihilating tumor cells. Nevertheless, the potential role of miR-325 in hepatocellular carcinoma (HCC) is still unknown.

Methods

Using RT-PCR, immunoblots invasion assays and bioinformatics strategies, we investigated the potential role of miR-325 in HCC.

Results

We showed that miR-325 was decreased and HMGB1 was increased in 99 patients with hepatocellular carcinoma. MiR-325 inhibition promoted cell invasion and proliferation, while miR-325 upregulation inhibited cell invasion and proliferation by using transwell and CCK8 assays. We further showed that HMGB1 might be a direct target of miR-325 and is negatively regulated by miR-325. Down-regulation of miR-325 predicts poor prognosis for HCC patients.

Conclusions

These findings implied that miR-325 regulates cell invasion and proliferation via targeting HMGB1 and may be a potential prognostic marker for HCC.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/4655707031717989

Clinical significance of hmgb1 expression in human gastric cancer

High mobility group box 1 (HMGB1) has been proved to be implicated in a variety of cell physiological and pathological behaviors including immune response, inflammation and cancer. Accumulating evidence suggests that HMGB1 plays a critical role in the development and progression of multiple malignancies. However, the clinical significance and prognosis of HMGB1 expression in some cancers remain controversial. The present study aimed to investigate whether overexpression of HMGB1 is an independent prognostic factor in patients with gastric cancer. The correlation of HMGB1 expression with clinicopathologic characteristics and prognosis was assessed by immunohistochemical assay through tissue microarray procedure in 50 primary gastric cancer cases. Our results indicated that the positive expression of HMGB1 was significantly increased in the nucleus of gastric cancer tissues compared with the adjacent non-cancerous tissues (ANCT) (64.0&#x0025; vs 44.0&#x0025;, P=0.025), but was not linked to the clinicopathologic features, including the TNM stage (P=0.533) and metastatic lymph node (P=0.771), in patients with gastric cancer. Kapalan-Meier and log-rank analysis demonstrated that overexpression of HMGB1 did not exert significant impact on the overall survival of patients with gastric cancer (P=0.805). Furthermore, Cox regression analysis showed that high HMGB1 protein expression did not represent an independent risk factor for patients with gastric cancer (P=0.677). Taken together, our findings suggest that high expression of HMGB1 is not correlated with the clinicopathologic characteristics of gastric cancer, and cannot serve as an independent prognostic biomarker for patients with gastric cancer.

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.

Topoisomerase IIα in chromosome instability and personalized cancer therapy

Genome instability is a hallmark of cancer cells. Chromosome instability (CIN), which is often mutually exclusive from hypermutation genotypes, represents a distinct subtype of genome instability. Hypermutations in cancer cells are due to defects in DNA repair genes, but the cause of CIN is still elusive. However, because of the extensive chromosomal abnormalities associated with CIN, its cause is likely a defect in a network of genes that regulate mitotic checkpoints and chromosomal organization and segregation. Emerging evidence has shown that the chromosomal decatenation checkpoint, which is critical for chromatin untangling and packing during genetic material duplication, is defective in cancer cells with CIN. The decatenation checkpoint is known to be regulated by a family of enzymes called topoisomerases. Among them, the gene encoding topoisomerase IIα (TOP2A) is commonly altered at both gene copy number and gene expression level in cancer cells. Thus, abnormal alterations of TOP2A, its interacting proteins, and its modifications may play a critical role in CIN in human cancers. Clinically, a large arsenal of topoisomerase inhibitors have been used to suppress DNA replication in cancer. However, they often lead to the secondary development of leukemia because of their effect on the chromosomal decatenation checkpoint. Therefore, topoisomerase drugs must be used judiciously and administered on an individual basis. In this review, we highlight the biological function of TOP2A in chromosome segregation and the mechanisms that regulate this enzyme's expression and activity. We also review the roles of TOP2A and related proteins in human cancers, and raise a perspective for how to target TOP2A in personalized cancer therapy.

HMGB1 promotes cellular proliferation and invasion, suppresses cellular apoptosis in osteosarcoma

Osteosarcoma is the most common primary malignant bone tumor in children and adolescents. Unfortunately, treatment failures are common due to the metastasis and chemoresistance, but the underlying molecular mechanism remains unclear. Accumulating evidence indicated that the deregulation of DNA-binding protein high-mobility group box 1 (HMGB1) was associated with the development of cancer. This study aimed to explore the expression of HMGB1 in osteosarcoma tissues and its correlation to the clinical pathology of osteosarcoma and to discuss the role of HMGB1 in the development of osteosarcoma. The results from RT-PCR and Western blot showed that the expression rate of HMGB1 messenger RNA (mRNA) and the expression of HMGB1 in the osteosarcoma tissues were significantly higher than those in normal bone tissue (p < 0.05), the expression rate of HMGB1 mRNA and the expression of HMGB1 in the carcinoma tissues with positive lung metastasis were significantly higher than those without lung metastasis (p < 0.05), and with increasing Enneking stage, the expression rate of HMGB1 mRNA and the expression of HMGB1 also increased (p < 0.05). In order to explore the role of HMGB1 in osteosarcoma, the expression of HMGB1 in the human osteosarcoma MG-63 cell line was downregulated by the technique of RNA interference. Western blot results showed that the protein expression of HMGB1 was significantly decreased in the MG-63 cells from HMGB1-siRNA transfection group (p < 0.05), which suggested that HMGB1 was successfully downregulated in the MG-63 cells. Then the changes in proliferation, apoptosis, and invasion of MG-63 cells were examined by MTT test, PI staining, annexin V staining, and transwell chamber assay. Results showed that the abilities of proliferation and invasion were suppressed in HMGB1 knockdown MG-63 cells, and the abilities of apoptosis were enhanced in HMGB1 knockdown MG-63 cells. The expression of cyclin D1, MMP-9 was downregulated in HMGB1 knockdown MG-63 cells, and the expression of caspase-3 was upregulated in HMGB1 knockdown MG-63 cells. Taken together, the overexpression of HMGB1 in osteosarcoma might be related to the tumorigenesis, invasion, and metastasis of osteosarcoma, which might be a potential target for the treatment of osteosarcoma.

Upregulation of miR-513b inhibits cell proliferation, migration, and promotes apoptosis by targeting high mobility group-box 3 protein in gastric cancer

The high mobility group-box 3 (HMGB3) protein belongs to the high mobility group box (HMG-box) subfamily, and recent studies have shown that HMGB3 is an oncogene for leukemia. HMGB3 is also expressed at a high level in the progression phase of breast and gastric cancer (GC). Using bioinformatic analyses, we found that HMGB3 is a potential target for miR-513b. However, the pathophysiological role of miR-513b and its relevance to the growth and development of GC have yet to be investigated. This study focuses on whether miR-513b acts as a tumor suppressor in GC. Compared with non-malignant adjacent tissues samples, qRT-PCR data showed significant downregulation of miR-513b in 74 GC tissue samples (P < 0.01). Furthermore, western blotting revealed that HMGB3 protein was overexpressed in tumor samples relative to matched, non-malignant adjacent tissues. Western blotting and qRT-PCR results showed that high expression of HMGB3 and low expression of miR-513b were both significantly associated with primary tumors, lymph node metastases, and the clinical stage (P < 0.01). MiR-513b was shown to not only inhibit the proliferation and migration of gastric cancer cells (MKN45 and SGC7901) in the CCK-8 and transwell assays, but also to promote cell apoptosis in a flow-cytometric apoptosis assay. In western blot and luciferase assays, HMGB3 was identified as a major target of miR-513b. Moreover, we also found that the expression of HMGB3 lacking in 3' UTR could abrogate the anti-migration and pro-apoptosis function of miR-513b. These findings suggest the importance of miR-513b targeting of HMGB3 in the regulation of growth, migration and apoptosis of GC, improve our understanding of the mechanisms of GC pathogenesis, and may promote the development of novel targeted therapies.

HMGB1 in hormone-related cancer: a potential therapeutic target

High-mobility group box 1 (HMGB1) is a dynamic nuclear protein participating in transcription, chromatin remodelling, and DNA recombination and repair processes. Accumulating evidence indicates that its function now extends beyond the nucleus, notably its extracellular role in inflammation. HMGB1 is implicated as a late mediator of sepsis and is also believed to promote atherosclerosis and other inflammatory diseases such as rheumatoid arthritis and systemic lupus erythematosus. Interestingly, deregulation of HMGB1 is shown to be associated with the hallmarks of cancer development. Moreover, several clinical studies have shown that HMGB1 is a promising biomarker for a variety of cancer types. In this review, we provide novel insights into the role and mechanisms of HMGB1, in particular, to hormone-related cancers and its potential to serve as a therapeutic target.

The role of high mobility group box 1 (HMGB1) in colorectal cancer

Background

HMGB1, the most important member of the high mobility group box protein family, is a nuclear protein with different functions in the cell; it has a role in cancer progression, angiogenesis, invasion, and metastasis development. We studied the expression of HMGB1 and whether it is a prognostic factor in colorectal carcinoma.

Material/Methods

The study included 110 cases that were histopathologically diagnosed with colorectal carcinoma from the tissue samples acquired by surgical resection and biopsy in Antalya Education and Research Hospital between 2008 and 2012. HMGB1 expression was examined via immunohistochemical method.

Results

HMGB1 expression was evaluated as negative in 32 (44.4%) of the patients and as positive in 40 (55.6%) patients. There was no relation between the HMGB1 expression and sex, age, tumor invasion depth, and histological type. However, a significant relation was detected between the HMGB1 expression and lymph node status, metastasis status, and stage (p:<0.001, p:<0.001, p:<0.001, respectively). Similar results were obtained for the relations between the HMGB1 and histological grade, perineural invasion, lymphovascular invasion, and lymphocytic response (p<0.001, p<0.001, p<0.001, and p<0.001, respectively).

Conclusions

The results of our study demonstrate that HMGB1 overexpression has a significant role in tumor progression (especially migration of tumor cells) and tumor ability to metastasize in colorectal cancers; thus, it corroborates the idea that it might be an important prognostic factor.

Knockdown of HMGB1 inhibits growth and invasion of gastric cancer cells through the NF-κB pathway in vitro and in vivo

High mobility group box 1 (HMGB1) as a novel inflammatory molecule has been shown to be involved in a variety of cell physiological and pathological behaviors including immune response, inflammation and cancer. Evidence suggests that HMGB1 plays a critical role in the development and progression of multiple malignancies. However, the underlying molecular mechanisms for the HMGB1-mediated growth and invasion of gastric cancer have not yet been elucidated. The present study investigated the expression of HMGB1 in gastric adenocarcinoma (GAC) and the mechanisms by which it contributes to tumor growth and invasion. The correlation between HMGB1 expression and clinicopathological characteristics of GAC patients was assessed by immunohistochemical assay through tissue microarray procedures. The RNA and protein expressions of HMGB1 and downstream factors were detected by quantitative PCR and western blot assays; cell proliferation and invasion were determined by MTT, wound-healing and 3D-Matregel assays, subcutaneous SGC-7901 tumor models were established to verify tumor growth in vivo. We demonstrated that, the expression of HMGB1 was significantly increased in the nucleus of GAC tissues compared with that in adjacent non-cancer tissues (88.6 vs.70.5%, P<0.001), and correlated with the metastatic lymph node of GAC (P=0.018). Furthermore, knockdown of HMGB1 by shRNA inhibited cell proliferative activities and invasive potential, and downregulated the expression of NF-κB p65, PCNA and MMP-9 in GAC cells (SGC-7901 and AGS). The tumor volumes in SGC7901 subcutaneous nude mouse models treated with Lv-shHMGB1 was significantly smaller than those of the nonsense sequence group. Taken together, these findings suggest that increased expression of HMGB1 is associated with tumor metastasis of GAC, and knockdown of HMGB1 suppresses growth and invasion of GAC cells through the NF-κB pathway in vitro and in vivo, suggesting that HMGB1 may serve as a potential therapeutic target for GAC.

High-mobility group box 1 (HMGB1) protein regulates tumor-associated cell migration through the interaction with BTB domain

High-mobility group box 1 (HMGB1) was shown to be strongly implicated in high incidences of metastasis and the poor clinical pathologic conditions found in various human tumors. In this study, we explored the possible mechanism of HMGB1 in tumor metastases in vitro, using a human carcinoma cell system. BTB, as a negative regulator of cell cycle progression, was identified as a HMGB1 interacting partner. The ectopic expression of HMGB1 activates cell growth by suppressing BTB-induced cell death, decreasing Bax and p53 expression, while enhancing Bcl-xL, Bcl-2, cyclin D1, and NF-κB expression. HMGB1 activates the FAK/PI3K/mTOR signaling cascade, and BTB prominently inhibits HMGB1-induced oncogenesis. The effect of HMGB1 on FAK/mTOR signaling was also confirmed through the silencing of HMGB1 expression. These insights provide evidence that HMGB1 enhances cell proliferation and suppresses apoptosis. Collectively, our results show an underlying mechanism for an HMGB1-associated promotion of carcinoma cells.

Evaluating cytoplasmic and nuclear levels of inflammatory cytokines in cancer cells by western blotting

Increased expression and cellular release of inflammatory cytokines, interleukin-8 (IL-8; CXCL8), and high mobility group box-1 (HMGB1) are associated with increased cell proliferation, angiogenesis, and metastasis during cancer progression. In prostate and ovarian cancer cells, increased levels of IL-8 and HMGB1 correlate with poor prognosis. We have recently shown that proteasome inhibition by bortezomib (BZ) specifically increases IL-8 release from metastatic prostate and ovarian cancer cells. In this chapter, we describe a protocol to analyze the cytoplasmic and nuclear levels of IL-8 and HMGB1 in prostate and ovarian cancer cells by western blotting. IL-8 is localized in the cytoplasm in both cell types, and its protein levels are significantly increased by BZ. In contrast, HMGB1 is localized in the nucleus, and BZ increases its nuclear levels only in ovarian cancer cells. The protocol includes isolation of cytoplasmic and nuclear extracts, followed by SDS electrophoresis and western blotting, and can be easily modified to analyze the cytoplasmic and nuclear cytokine levels in other cell types.

HMGB1 combining with tumor-associated macrophages enhanced lymphangiogenesis in human epithelial ovarian cancer

Within tumor microenvironment, high-mobility group box protein 1 (HMGB1) and tumor-associated macrophages (TAMs) are able to influence ovarian cancer development and progression via facilitating tumor lymphatic metastasis. However, little is known about the association between HMGB1 and TAMs on lymphangiogenesis in epithelial ovarian cancer (EOC). To investigate the effect of HMGB1 and TAMs on lymphangiogenesis in EOC, immunohistochemistry was performed to determine the expressions of HMGB1, TAMs, and lymphatic vessel density (LVD) in a total of 108 ovarian tissue specimens. Then, the relationships between HMGB1 or TAMs and LVD were assessed by correlation test. In our in vitro study, TAMs were isolated from ascites of EOC patients. Effects of HMGB1, TAMs, and HMGB1 combining with TAMs on lymphatic endothelial cell (LEC) proliferation, migration, and the capillary-like tube formation were measured. Results showed that the expression of HMGB1 and the number of TAMs infiltration were overexpressed in malignant ovarian tumors compared with that in normal ovarian and were closely associated with lymph node metastasis. Positive correlations existed between HMGB1 expression or TAMs count and LVD determination. In an in vitro study, data demonstrated that either HMGB1 or TAMs could facilitate lymphangiogenesis by inducing LEC proliferation, migration, and capillary-like tube formation. Meanwhile, HMGB1 combining with TAMs may augment the pro-lymphangiogenic property. Our data suggest that either HMGB1 or TAMs could facilitate lymphangiogenesis, while HMGB1 coculture with TAMs may strengthen the pro-lymphangiogenic potential, which may serve as a therapeutic target for ovarian cancer.