Receptor for advanced glycation end products (RAGE) partially mediates HMGB1-ERKs activation in clear cell renal cell carcinoma

HMGB1/RAGE axis in tumor development: unraveling its significance

High mobility group protein 1 (HMGB1) plays a complex role in tumor biology. When released into the extracellular space, it binds to the receptor for advanced glycation end products (RAGE) located on the cell membrane, playing an important role in tumor development by regulating a number of biological processes and signal pathways. In this review, we outline the multifaceted functions of the HMGB1/RAGE axis, which encompasses tumor cell proliferation, apoptosis, autophagy, metastasis, and angiogenesis. This axis is instrumental in tumor progression, promoting tumor cell proliferation, autophagy, metastasis, and angiogenesis while inhibiting apoptosis, through pivotal signaling pathways, including MAPK, NF-κB, PI3K/AKT, ERK, and STAT3. Notably, small molecules, such as miRNA-218, ethyl pyruvate (EP), and glycyrrhizin exhibit the ability to inhibit the HMGB1/RAGE axis, restraining tumor development. Therefore, a deeper understanding of the mechanisms of the HMGB1/RAGE axis in tumors is of great importance, and the development of inhibitors targeting this axis warrants further exploration.

Antigenic targets in clear cell renal cell carcinoma

Immune checkpoint inhibitors (ICIs) have transformed the management of advanced renal cell carcinoma (RCC), but most patients still do not receive a long-term benefit from these therapies, and many experience off-target, immune-related adverse effects. RCC is also different from many other ICI-responsive tumors, as it has only a modest mutation burden, and total neoantigen load does not correlate with ICI response. In order to improve the efficacy and safety of immunotherapies for RCC, it is therefore critical to identify the antigens that are targeted in effective anti-tumor immunity. In this review, we describe the potential classes of target antigens, and provide examples of previous and ongoing efforts to investigate and target antigens in RCC, with a focus on clear cell histology. Ultimately, we believe that a concerted antigen discovery effort in RCC will enable an improved understanding of response and resistance to current therapies, and lay a foundation for the future development of "precision" antigen-directed immunotherapies.

RAGE Inhibitors for Targeted Therapy of Cancer: A Comprehensive Review

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin family that is overexpressed in several cancers. RAGE is highly expressed in the lung, and its expression increases proportionally at the site of inflammation. This receptor can bind a variety of ligands, including advanced glycation end products, high mobility group box 1, S100 proteins, adhesion molecules, complement components, advanced lipoxidation end products, lipopolysaccharides, and other molecules that mediate cellular responses related to acute and chronic inflammation. RAGE serves as an important node for the initiation and stimulation of cell stress and growth signaling mechanisms that promote carcinogenesis, tumor propagation, and metastatic potential. In this review, we discuss different aspects of RAGE and its prominent ligands implicated in cancer pathogenesis and describe current findings that provide insights into the significant role played by RAGE in cancer. Cancer development can be hindered by inhibiting the interaction of RAGE with its ligands, and this could provide an effective strategy for cancer treatment.

Occupational disparities in tumor grade and cytosolic HMGB1 expression in renal cell cancer

Objectives

We sought to examine occupational disparities in tumor grade and cytosolic expression of high‐mobility group box‐1 (HMGB1) among renal cell cancer (RCC) patients.

Methods

This retrospective study included 318 RCC patients with complete information on occupation and pathology in Kanagawa Cancer Registry (KCR). Longest‐held occupations were grouped into manual workers (e.g., manufacturing, construction) versus “others.” Odds ratios (OR) and 95% confidence intervals (CI) for high‐grade histology were estimated by logistic regression, adjusted for age and sex. We also examined a sub‐sample of 74 low‐grade RCC inpatients to estimate the OR for positive cytosolic HMGB1 expression in manual workers, adjusting for age, sex, and other available covariates.

Results

High‐grade tumors were more prevalent in manual workers compared to other occupations: 23.0% (14/61) versus 10.9% (28/257, p = .01) with an adjusted OR of 2.28 (95% CI, 1.11–4.69). In the sub‐sample of low‐grade RCCs, positive cytosolic HMGB1 expression was more prevalent in manual workers compared to other occupations: 71.4% (10/14) versus 38.3% (23/60, p = .03) with a sex‐ and age‐adjusted OR of 3.76 (95% CI, 1.03–13.7).

Conclusions

Manual workers are associated with increased risks of high‐grade renal cell tumors and cytosolic HMGB1 expression.

Antigene and Antiproliferative Effects of Triplex-Forming Oligonucleotide (TFO) Targeted on hmgb1 Gene in Human Hepatoma Cells

BACKGROUND

The high mobility group box 1 (hmgb1) is one of the frequently over-expressed genes whose aberrant expression is reported in a number of human cancers. Various strategies are underway to inhibit hmgb1 expression in cancer cells having considerable therapeutic value.

OBJECTIVE

The present work involves selective transcriptional inhibition of the hmgb1 gene using selective DNA triplex structure-based gene technology. Here, the promoter region of the hmgb1 gene at position (-183 to -165) from the transcription start site as a target was selected using bioinformatic tools.

METHODS

The DNA triplex formation by the DNA of the target gene and TFO was confirmed using UV absorption spectroscopy, Circular Dichroism, and Isothermal Calorimetry.

RESULTS

Treatment of HepG2 cell with specific Triplex-forming Oligonucleotide significantly downregulated HMGB1 expression level at mRNA and protein levels by 50%, while the classical anticancer drugs, actinomycin/ adriamycin as positive controls showed 65% and the combination of TFO and drug decreased by 70%. The anti-proliferative effects of TFO correlated well with the fact of accumulation of cells in the Go phase and apoptotic cell death. Further, the binding of anti-cancer drugs to hmgb1 is stronger in DNA triplex state as compared to hmgb1 alone, suggesting the combination therapy as a better option.

CONCLUSION

Therefore, the ability of hmgb1 targeted triplex-forming oligonucleotide in combination with triplex selective anticancer drug holds promise in the treatment of malignancies associated with hmgb1 overexpression. The result obtained may open up new vistas to provide a basis for the rational drug design and searching for high-affinity ligands with a high triplex selectivity.

Intratumoral Fibrosis in Facilitating Renal Cancer Aggressiveness: Underlying Mechanisms and Promising Targets

Intratumoral fibrosis is a histologic manifestation of fibrotic tumor stroma. The interaction between cancer cells and fibrotic stroma is intricate and reciprocal, involving dysregulations from multiple biological processes. Different components of tumor stroma are implicated via distinct manners. In the kidney, intratumoral fibrosis is frequently observed in renal cell carcinoma (RCC). However, the underlying mechanisms remain largely unclear. In this review, we recapitulate evidence demonstrating how fibrotic stroma interacts with cancer cells and mechanisms shared between RCC tumorigenesis and renal fibrogenesis, providing promising targets for future studies.

Diabetes and Pancreatic Cancer-A Dangerous Liaison Relying on Carbonyl Stress

Both type 2 (T2DM) and type 1 (T1DM) diabetes mellitus confer an increased risk of pancreatic cancer in humans. The magnitude and temporal trajectory of the risk conferred by the two forms of diabetes are similar, suggesting a common mechanism. Carbonyl stress is a hallmark of hyperglycemia and dyslipidemia, which accompanies T2DM, prediabetes, and obesity. Accumulating evidence demonstrates that diabetes promotes pancreatic ductal adenocarcinoma (PDAC) in experimental models of T2DM, a finding recently confirmed in a T1DM model. The carbonyl stress markers advanced glycation end-products (AGEs), the levels of which are increased in diabetes, were shown to markedly accelerate tumor development in a mouse model of Kras-driven PDAC. Consistently, inhibition of AGE formation by trapping their carbonyl precursors (i.e., reactive carbonyl species, RCS) prevented the PDAC-promoting effect of diabetes. Considering the growing attention on carbonyl stress in the onset and progression of several cancers, including breast, lung and colorectal cancer, this review discusses the mechanisms by which glucose and lipid imbalances induce a status of carbonyl stress, the oncogenic pathways activated by AGEs and their precursors RCS, and the potential use of carbonyl-scavenging agents and AGE inhibitors in PDAC prevention and treatment, particularly in high-risk diabetic individuals.

HN1L promotes migration and invasion of breast cancer by up-regulating the expression of HMGB1

Recent reports showed that haematological and neurological expressed 1-like (HN1L) gene participated in tumorigenesis and tumour invasion. However, the expression and role of HN1L in breast cancer remain to be investigated. Here, bioinformatics, western blot and immunohistochemistry were used to detect the expression of HN1L in breast cancer. Wound healing, transwell assay, immunofluorescence assay and mass spectrum were used to explore the role and mechanism of HN1L on the migration and invasion of breast cancer, which was confirmed in vivo using a nude mice model. Results showed that HN1L was significantly over-expressed in breast cancer tissues, which was positively correlated with M metastasis of breast cancer patients. Silencing HN1L significantly inhibited the invasion and metastasis of breast cancer cells in vitro and lung metastasis in nude mice metastasis model of breast cancer. Mechanistically, HN1L interacted with HSPA9 and affected the expression of HMGB1, playing a key role in promoting the invasion and metastasis of breast cancer cell. These results suggested that HN1L was an appealing drug target for breast cancer.

HMGB1 in kidney diseases

High mobility group box 1 (HMGB1) is a highly conserved nucleoprotein involving in numerous biological processes, and well known to trigger immune responses as the damage-associated molecular pattern (DAMP) in the extracellular environment. The role of HMGB1 is distinct due to its multiple functions in different subcellular location. In the nucleus, HMGB1 acts as a chaperone to regulate DNA events including DNA replication, repair and nucleosome stability. While in the cytoplasm, it is engaged in regulating autophagy and apoptosis. A great deal of research has explored its function in the pathogenesis of renal diseases. This review mainly focuses on the role of HMGB1 and summarizes the pathway and treatment targeting HMGB1 in the various renal diseases which may open the windows of opportunities for the development of desirable therapeutic ends in these pathological conditions.

Role and Mechanisms of RAGE-Ligand Complexes and RAGE-Inhibitors in Cancer Progression

Interactions of the receptor for advanced glycation end product (RAGE) and its ligands in the context of their role in diabetes mellitus, inflammation, and carcinogenesis have been extensively investigated. This review focuses on the role of RAGE-ligands and anti-RAGE drugs capable of controlling cancer progression. Different studies have demonstrated interaction of RAGE with a diverse range of acidic (negatively charged) ligands such as advanced glycation end products (AGEs), high-mobility group box1 (HMGB1), and S100s, and their importance to cancer progression. Some RAGE-ligands displayed effects on anti- and pro-apoptotic proteins through upregulation of the phosphatidylinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR), mitogen-activated protein kinases (MAPKs), matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF), and nuclear factor kappa B (NF-κB) pathways, while downregulating p53 in cancer progression. In addition, RAGE may undergo ligand-driven multimodal dimerization or oligomerization mediated through self-association of some of its subunits. We conclude our review by proposing possible future lines of study that could result in control of cancer progression through RAGE inhibition.

A novel diagnostic tool for the detection of bladder cancer: Measurement of urinary high mobility group box-1

OBJECTIVE

We aimed to investigate the diagnostic value of urinary High Mobility Group Box-1 (HMGB1) level as a noninvasive tool that can be potentially used for diagnosis and during follow-up in patients with bladder cancer patients.

METHOD

The study was conducted in a total of 121 participants including 61 patients diagnosed with primary bladder cancer, 30 patients with an acute urinary tract infection and 30 healthy controls. Age, gender and urinary HMGB1 levels of the study groups were evaluated. The association of clinical features (tumor diameter, number of foci, pathological grade, muscle invasion) with urinary HMGB1 levels was investigated in patients with bladder cancer.

RESULTS

All 3 groups showed a normal age and gender distribution with no significant difference among them (P = 0.775 and P = 0.967, respectively). A significant difference was detected in urinary HMGB1 levels among the 3 groups (P < 0.001). When urinary HMGB1 levels were compared between patients with high grade vs. low grade tumors, the mean HMGB1 level was 44.39 pg/ml (12.1-505.2) in patients with low grade tumors and 280 pg/ml (18.7-2685.3) in patients with high grade tumors (P < 0.001). Patients with a greater number of tumor foci had higher HMGB1 levels in comparison to patients with a single tumor focus (P = 0.008). Urinary HMGB1 levels were higher in patients with a tumor diameter of ≥3 cm than in patients with a tumor diameter less than 3 cm (P = 0.001). Patients with muscle-invasive bladder cancer exhibited higher urinary HMGB1 levels compared to patients with non-muscle-invasive bladder cancer (P = 0.033). The cut-off values derived from the ROC analysis were 63.30 pg/ml for distinguishing bladder cancer from urinary tract infection, 30.94 pg/ml for urinary tract infection versus control group and 38.70 pg/ml for bladder cancer vs. control group, respectively. Sensitivity was 59% and specificity was found 77%.

CONCLUSION

In future controlled studies involving larger patient groups, urinary HMGB1 levels can be used for diagnostic and screening purposes in bladder cancer patients.

S100B as an Antagonist To Interfere with the Interface Area Flanked by S100A11 and RAGE V Domain

The Ca²⁺-sensing protein S100A11 of the S100 family is an important mediator of numerous biological functions and pathological conditions including cancer. The receptor for advanced glycation end products (RAGE) has been well accepted as the major receptor for several S100 family members. Here, we take the S100B protein as an antagonist to interfere with the interaction flanked by S100A11 and the RAGE V domain. We employed NMR spectroscopy to describe the interactions between the S100A11 and S100B proteins. ¹H-¹⁵N heteronuclear single-quantum correlation-NMR titrations showed the potential binding dynamics of S100A11 and S100B interactions. In the HADDOCK program, we constructed the S100A11-S100B heterodimer complex that was then superimposed with the S100A11-S100B complex structure in the same orientation as the S100A11-RAGE V domain complex. This overlay analysis showed that S100B could interfere in the binding section of S100A11 and the RAGE V domain. Additionally, water-soluble tetrazolium-1 assay provided a functional read-out of the effects of these proteins in an in vitro cancer model. Our study establishes that the development of an S100B antagonist could perform a vital part in the treatment of S100- and RAGE-dependent human diseases.

HMGB1/RAGE axis mediates the apoptosis, invasion, autophagy, and angiogenesis of the renal cell carcinoma

Background

High mobility group box 1 protein (HMGB1) is a sort of non-histone protein in chromatin, which plays an important role in tumor proliferation, invasion, and immune escape. HMGB1-RAGE (receptor for advanced glycation end products) interactions have been reported to be important in a number of cancers.

Methods

CCK8, flow cytometry and qRT-PCR were used to detected cell viability, apoptosis and gene expression, respectively.

Results

In the present study, we demonstrated that HMGB1/RAGE axis regulated the cell proliferation, apoptosis, and invasion of the renal cell carcinoma (RCC). Further, we discovered that HMGB1/RAGE axis increased the expression of autophagic proteins LC3 and Beclin-1 in RCC. Finally, we used a coculture model of human umbilical vein endothelial cells with RCC cell lines to find out that HMGB1 also increased the expression of VEGF and VEGFR2 in human umbilical vein endothelial cells. An in vivo study further confirmed that HMGB1 knockdown inhibited RCC tumor growth.

Conclusion

Our results illustrated that HMGB1/RAGE axis mediated RCC cell viability, apoptosis, invasion, autophagy, and angiogenesis, which provides a novel theoretical basis for using HMGB1 as the target in RCC.

Patient derived renal cell carcinoma xenografts exhibit distinct sensitivity patterns in response to antiangiogenic therapy and constitute a suitable tool for biomarker development

Systemic treatment is necessary for one third of patients with renal cell carcinoma. No valid biomarker is currently available to tailor personalized therapy. In this study we established a representative panel of patient derived xenograft (PDX) mouse models from patients with renal cell carcinomas and determined serum levels of high mobility group B1 (HMGB1) protein under treatment with sunitinib, pazopanib, sorafenib, axitinib, temsirolimus and bevacizumab. Serum HMGB1 levels were significantly higher in a subset of the PDX collection, which exhibited slower tumor growth during subsequent passages than tumors with low HMGB1 serum levels. Pre-treatment PDX serum HMGB1 levels also correlated with response to systemic treatment: PDX models with high HMGB1 levels predicted response to bevacizumab. Taken together, we provide for the first time evidence that the damage associated molecular pattern biomarker HMGB1 can predict response to systemic treatment with bevacizumab. Our data support the future evaluation of HMGB1 as a predictive biomarker for bevacizumab sensitivity in patients with renal cell carcinoma.

Overexpression of high mobility group box 1 contributes to progressive clinicopathological features and poor prognosis of human bladder urothelial carcinoma

Background

High mobility group box 1 (HMGB1), a versatile protein with intranuclear and extracellular functions, plays an important role in a variety of human cancers. However, the clinical/prognostic significance of HMGB1 expression in human bladder urothelial carcinoma (BUC) remains unclear. The aim of this study was to investigate the HMGB1 expression in human BUC with regard to its clinical and prognostic significance.

Patients and methods

HMGB1 mRNA and protein expressions in tumor and paired normal bladder tissues were detected in 20 BUC cases by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. HMGB1 protein expression in 165 primary BUC tissues was evaluated by immunohistochemistry (IHC), and its correlations with clinicopathological characteristics and prognosis were also analyzed. Student’s t-test, χ² test, Kaplan–Meier plots, and Cox proportional hazard regression model were performed to analyze the data.

Results

By using qRT-PCR and Western blot, the upregulated expression of HMGB1 mRNA and protein was detected in BUC, compared with paired normal tissue (P<0.05). By using IHC, high HMGB1 expression was examined in 84 of 165 (51.0%) BUC cases. High HMGB1 expression was significantly correlated with poorer differentiation and higher T and N classification (all P<0.05). Univariate analysis showed that high HMGB1 expression was significantly associated with a shortened patients’ overall survival (OS) and disease-free survival (DFS; both P<0.001). In different subgroups of BUC patients, HMGB1 expression was a prognostic factor in patients with different histological grades or T classification (all P<0.05), pN− (both P<0.001) for OS and DFS, and pT1/pN− (P<0.05) for OS. HMGB1 expression, as well as pT and pN status, was an independent prognostic factor for both OS (P=0.001, hazard ratio [HR] =2.973, 95% confidence interval [CI] =1.550–5.704) and DFS (P<0.001, HR =3.019, 95% CI =1.902–4.792) in multivariate analysis.

Conclusion

Overexpression of HMGB1 may be a new independent molecular marker for the poor prognosis of patients with BUC.

HMGB1 promotes myeloid-derived suppressor cells and renal cell carcinoma immune escape

Despite high immunogenicity and marked presence of immune cells in the RCC(renal cell carcinoma), immunotherapy fails to develop effective anti-tumor immune responses. This is due to the negative regulatory factors in the tumor microenvironment. As the main contributor of immunosuppression, myeloid-derived suppressor cells (MDSCs) inhibited anti-tumor immunity and promoted tumor progression. Meanwhile, it is confirmed that high mobility group box-1 protein (HMGB1) shows a high expression in many solid tumors and HMGB1 with high expression is involved in tumor immune escape. However, the mechanisms linking HMGB1 with tumor immune escape are unclear. The present study aimed to explore whether HMGB1 can promote RCC immune escape by inducing the generation of MDSCs. In this study, Renca mouse model was established and the influence of HMGB1 on MDSCs was investigated by using HMGB1 antibody to downregulate the expression of HMGB1 in tumor-bearing mice. The result showed that with the down-regulation of HMGB1, the tumor growth was inhibited significantly and the mice survival was prolonged greatly. Furthermore, the differentiation and proliferation of MDSCs were inhibited both in vitro and in vivo, and the inhibition rate showed a positive correlation with the degree of down-regulation of HMGB1. When MDSCs were eliminated with Gr-1 antibody in vivo, the ability of the HMGB1 to promote tumor growth was severely impaired. Thus, our findings indicated that HMGB1 might mediate tumor immune escape by promoting MDSCs cell proliferation, which provided a novel theoretical basis for preventing RCC using HMGB1 as the target.

Hypoxia driven glycation: Mechanisms and therapeutic opportunities

Tumor masses are deprived of oxygen and characterized by enhanced glucose uptake followed by glycolysis. Elevated glucose levels induce non-enzymatic glycosylation or glycation of proteins which leads to accumulation of advanced glycation end products (AGE). These AGE molecules bind to their respective receptors called the receptor for advanced glycation end products (RAGE) and initiate several aberrant signaling pathways leading to onset of diseases such as diabetes, Alzheimer's, atherosclerosis, heart failure and cancer. The role of AGE in cancer progression is being extensively studied in recent years. As cancer cells are hypoxic in nature and adapted to glycolysis, which induces glycation, its effects need to be understood in greater detail. Since AGE-RAGE signaling is involved in cancer progression, inhibition of AGE-RAGE interaction could be a potential therapeutic target. The purpose of this review is to highlight the role of AGE-RAGE interaction in hypoxic cancer cells.

High-Mobility Group Box 1 Disrupts Metabolic Function with Cigarette Smoke Exposure in a Ceramide-Dependent Manner

We have previously found that cigarette smoke disrupts metabolic function, in part, by increasing muscle ceramide accrual. To further our understanding of this, we sought to determine the role of the cytokine high-mobility group box 1 (HMGB1), which is increased with smoke exposure, in smoke-induced muscle metabolic perturbations. To test this theory, we determined HMGB1 from lungs of human smokers, as well as from lung cells from mice exposed to cigarette smoke. We also treated cells and mice directly with HMGB1, in the presence or absence of myriocin, an inhibitor of serine palmitoyltransferase, the rate-limiting enzyme in ceramide biosynthesis. Outcomes included assessments of insulin resistance and muscle mitochondrial function. HMGB1 was significantly increased in both human lungs and rodent alveolar macrophages. Further testing revealed that HMGB1 treatment elicited a widespread increase in ceramide species and reduction in myotube mitochondrial respiration, an increase in reactive oxygen species, and reduced insulin-stimulated Akt phosphorylation. Inhibition of ceramide biosynthesis with myriocin was protective. In mice, by comparing treatments of HMGB1 injections with or without myriocin, we found that HMGB1 injections resulted in increased muscle ceramides, especially C16 and C24, which were necessary for reduced muscle mitochondrial respiration and compromised insulin and glucose tolerance. In conclusion, HMGB1 may be a necessary intermediate in the ceramide-dependent metabolic consequences of cigarette smoke exposure.

Serum levels of HMGB1 have a diagnostic role in metastatic renal cell cancer

RCC constitutes approximately 90% of all renal malignancies and 2-3% of all malignant tumours in adults. In spite of the improvement in radiologic methods, nearly 30% of the early metastatic RCC patients are incidentally diagnosed. HMGB1 is an extracellular signalling molecule that plays a role both in inflammation and carcinogenesis. Patients who were followed in Medical Oncology Departments of Denizli Government Hospital and Antalya Education and Research Hospital with a histopathological diagnosis of RCC between years 2010-2012 were enrolled in this study. HMGB1 levels were also assessed in a manually performed quantitative sandwich-enzyme-linked immunosorbent assay (ELISA) assay kit. In our study, we showed that the serum level of HMGB1, whether 149.9 pg/ml or not is important in differential diagnosis between patient and control group.

High-mobility group box 1 inhibits HCO3- absorption in the medullary thick ascending limb through RAGE-Rho-ROCK-mediated inhibition of basolateral Na+/H+ exchange

High-mobility group box 1 (HMGB1) is a nuclear protein released extracellularly in response to infection or injury, where it activates immune responses and contributes to the pathogenesis of kidney dysfunction in sepsis and sterile inflammatory disorders. Recently, we demonstrated that HMGB1 inhibits HCO3 (-) absorption in perfused rat medullary thick ascending limbs (MTAL) through a basolateral receptor for advanced glycation end products (RAGE)-dependent pathway that is additive to Toll-like receptor 4 (TLR4)-ERK-mediated inhibition by LPS (Good DW, George T, Watts BA III. Am J Physiol Renal Physiol 309: F720-F730, 2015). Here, we examined signaling and transport mechanisms that mediate inhibition by HMGB1. Inhibition of HCO3 (-) absorption by HMGB1 was eliminated by the Rho-associated kinase (ROCK) inhibitor Y27632 and by a specific inhibitor of Rho, the major upstream activator of ROCK. HMGB1 increased RhoA and ROCK1 activity. HMGB1-induced ROCK1 activation was eliminated by the RAGE antagonist FPS-ZM1 and by inhibition of Rho. The Rho and ROCK inhibitors had no effect on inhibition of HCO3 (-) absorption by bath LPS. Inhibition of HCO3 (-) absorption by HMGB1 was eliminated by bath amiloride, 0 Na(+) bath, and the F-actin stabilizer jasplakinolide, three conditions that selectively prevent inhibition of MTAL HCO3 (-) absorption mediated through NHE1. HMGB1 decreased basolateral Na(+)/H(+) exchange activity through activation of ROCK. We conclude that HMGB1 inhibits HCO3 (-) absorption in the MTAL through a RAGE-RhoA-ROCK1 signaling pathway coupled to inhibition of NHE1. The HMGB1-RAGE-RhoA-ROCK1 pathway thus represents a potential target to attenuate MTAL dysfunction during sepsis and other inflammatory disorders. HMGB1 and LPS inhibit HCO3 (-) absorption through different receptor signaling and transport mechanisms, which enables these pathogenic mediators to act directly and independently to impair MTAL function.

The role of high mobility group box 1 (HMGB1) in the pathogenesis of kidney diseases

High mobility group box 1 (HMGB1) is a nuclear protein that can bind to DNA and act as a co-factor for gene transcription. When released into extracellular fluid, it plays a proinflammatory role by acting as a damage-associated molecular pattern molecule (DAMP) (also known as an alarmin) to initiate innate immune responses by activating multiple cell surface receptors such as the receptor for advanced glycation end-products (RAGE) and toll-like receptors (TLRs), TLR2, TLR4 or TLR9. This proinflammatory role is now considered to be important in the pathogenesis of a wide range of kidney diseases whether they result from hemodynamic changes, renal tubular epithelial cell apoptosis, kidney tissue fibrosis or inflammation. This review summarizes our current understanding of the role of HMGB1 in kidney diseases and how the HMGB1-mediated signaling pathway may constitute a new strategy for the treatment of kidney diseases.

Blockade of high mobility group box-1 signaling via the receptor for advanced glycation end-products ameliorates inflammatory damage after acute intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating disease with no specific treatment. Increasing evidence indicates that inflammatory response plays a critical role in ICH-induced damage. High mobility group box-1 protein (HMGB1) may trigger inflammatory response via three putative receptors: receptor for advanced glycation end-products (RAGE), toll-like receptor-2 (TLR2) and toll-like receptor-4 (TLR4). Which receptor participates in HMGB1-induced inflammation during acute ICH is unknown. Using a rat model to examine the early phase of injury in collagenase-induced ICH, we found that treating animals with HMGB1 antagonist significantly reduced the expression of all three receptors. Treating animals with the HMGB1 antagonist EP or RAGE antagonist FPS-ZM1 significantly reduced inflammatory cell infiltration and expression of IL-1β, matrix metalloproteinase-9 in the perihematoma after ICH. Treatment with EP or FPS-ZM1 also led to greater neurobehavioral function and less brain edema, hemorrhage volume and brain damage after ICH. In contrast, treatment with TLR2/4 antagonists did not significantly affect these post-ICH outcomes. Our results suggest that RAGE may play a specific role in the acute phase of ICH, so targeting the HMGB1-RAGE signaling pathway may be a promising therapeutic strategy.

Down-regulation of HMGB1 expression by shRNA constructs inhibits the bioactivity of urothelial carcinoma cell lines via the NF-κB pathway

The high mobility group box 1 (HMGB1), which is a highly conserved and evolutionarily non-histone nuclear protein, has been shown to associate with a variety of biological important processes, such as transcription, DNA repair, differentiation, and extracellular signalling. High HMGB1 expression has been reported in many cancers, such as prostate, kidney, ovarian, and gastric cancer. However, there have been few studies of the function of HMGB1 in the malignant biological behaviour of bladder urothelial carcinoma (BUC), and the potential mechanism of HMGB1 in the pathogenesis of BUC remains unclear. Thus, in this study, we constructed plasmid vectors that are capable of synthesizing specific shRNAs targeting HMGB1 and transfected them into BUC cells to persistently suppress the endogenous gene expression of HMGB1. The expression of HMGB1, the bioactivity of BUC cells, including proliferation, apoptosis, cell cycle distribution, migration and invasion, and the effects of HMGB1 knockdown on downstream signalling pathways were investigated. Our data suggest that HMGB1 promotes the malignant biological behaviour of BUC, and that this effect may be partially mediated by the NF-κB signalling pathway. HMGB1 may serve as a potential therapeutic target for BUC in the future.

Netrin-1: The new tumor markers in renal clear cell carcinoma

OBJECTIVE

To explore the expression of Netrin-1 protein in human renal clear cell carcinoma (RCCC) and the relationships between Netrin-1, pathology and prognosis.

METHODS

72 cases of RCCC admitted in our hospital from 2008 June to 2009 June and their adjacent tissues were selected for study. They included 30 cases in stage Ⅰ-Ⅱ, 42 cases in stage Ⅲ-Ⅳ; 9 cases in grade Ⅰ, 9 cases in grade Ⅱ, 40 cases in grade Ⅲ and 14 cases in grade Ⅳ. All cases were followed up for more than 5 years. Survival analysis lines were made by Kaplan-Meier method and the difference between groups was tested by the Log-rank test. The expression of Netrin-1 protein was detected by immunohistochemistry staining and its clinical significance was analyzed.

RESULTS

Renal clear cell carcinoma: 51 cases in high expression of Netrin-1 and 21 cases in low expression, normal tissues: 12 cases in high expression of Netrin-1 and 60 cases in low expression, the difference between the two groups is significant (χ(2) = 42.921, P ＜ 0.01). The difference of the expression of Netrin-1in Fuhrman grade and AJCC clinical stage is significant (χ(2) = 8.000, χ(2) = 6.203; P＜0.05). The 5-year survival rate in low protein expression group and in high protein expression group was 79％ (17/21) and 62％ (32/51). The survival curve had different trend, with no significant difference between groups ((χ(2) = 1.360, P = 0.245).

CONCLUSIONS

Netrin-1 protein plays an important role in the development of RCCC. It might be a new specific tumor marker of RCCC, and might become a new target in treatment of RCCC.

Increased HMGB1 and cleaved caspase-3 stimulate the proliferation of tumor cells and are correlated with the poor prognosis in colorectal cancer

Background

Dying tumor cells after irradiation could promote the proliferation of living tumor cells might cause tumor relapse and treatment failure. Our previous study showed that activated caspase-3 after irradiation probably participates in tumor repopulation. In this study, we investigated whether high mobility group box 1(HMGB1) is also involved in tumor repopulation.

Methods

Colorectal tumor cells were irradiated. The cleaved caspase-3 (CC3) in irradiated tumor cells and HMGB1 in the supernatant of irradiated tumor cells were detected by Western blot. A large number of irradiated colorectal tumor cells (feeder cells) were then co-cultured with a small number of luciferase-labeled living colorectal tumor cells (reporter cells) and proliferation of reporter cells was measured by bioluminescence imaging. The CC3 and HMGB1 protein expression in colorectal tumor and peritumoral tissues were detected by immunohistochemistry and their correlation with prognosis were analyzed.

Results

The irradiated colorectal tumor cells underwent apoptosis and necrosis and produced CC3 in tumor cells and HMGB1 in the supernatant of cultured cells. The increased expression of secretory HMGB1 correlated with CC3 level and proliferating cell nuclear antigen (PCNA) after irradiation in vitro. The irradiated dying cells remarkably stimulated living tumor cell proliferation. Interestedly, immunohistochemistry staining showed that positive HMGB1, CC3, and Ki67 expression were significantly higher in colorectal tumor tissues than in peritumoral tissues (p <0.01). The Kaplan-Meier survival analysis revealed that high HMGB1, CC3, and Ki67 levels were significantly associated with poor prognosis (p <0.05, p <0.01). Multivariate analysis using Cox proportional hazards model showed that TNM staging and HMGB1 were independent prognostic factors in patients with colorectal cancer (CRC) (p <0.01, p <0.001).

Conclusion

Both apoptotic and necrotic cells could stimulate proliferation of living tumor cells, and the increased expression of CC3 and HMGB1 in tumor cells could be new markers for poor prognosis in colorectal cancer patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0166-1) contains supplementary material, which is available to authorized users.

Soluble receptor for advanced glycation end products inhibits disease progression in autosomal dominant polycystic kidney disease by down-regulating cell proliferation

Autosomal polycystic kidney disease (ADPKD) is a highly prevalent genetic renal disorder in which epithelial-lining fluid-filled cysts appear in kidneys. It is accompanied by hyperactivation of cell proliferation, interstitial inflammation, and fibrosis around the cyst lining cells, finally reaching end-stage renal disease. Previously, we found high expression of ligands stimulating the receptor for advanced glycation end products (RAGE) in ADPKD mice. Furthermore, gene silencing of RAGE was revealed to cause reduction of cystogenesis via down-regulation of cell proliferation in vitro, and intravenous administration of anti-RAGE adenovirus in vivo also displayed alleviation of the disease. Here, we attempted to identify the role of soluble RAGE (sRAGE) in inhibiting the progression of ADPKD using 2 different ADPKD mouse models. sRAGE is an endogenously expressed form of RAGE that has no membrane-anchoring domain, thereby giving it the ability to neutralize the ligands that stimulate RAGE signals. Both overexpression of sRAGE and sRAGE treatment blocked RAGE-mediated cell proliferation in vitro. In addition, sRAGE-injected ADPKD mice showed reduced cysts accompanied by enhanced renal function, inhibition of cell proliferation, inflammation, and fibrosis. These positive therapeutic effects of sRAGE displayed little liver toxicity, suggesting it as a new potential therapeutic target of ADPKD with low side effects.

Autophagy-mediated HMGB1 release promotes gastric cancer cell survival via RAGE activation of extracellular signal-regulated kinases 1/2

High mobility group box-B1 (HMGB1), an autophagy activator, is crucial in tumorigenesis. However, its extracellular role and signaling in gastric cancer remain unclear. Samples were collected from gastric cancer patients and healthy controls. Immunohistochemistry and immunocytochemistry were used to determine the localization of HMGB1 in gastric cancer tissues, four gastric carcinoma cell lines (BGC-823, SGC-7901, MKN-28 and MKN-45) and a gastric epithelial cell line GES-1. Western blot analysis and ELISA were used to assess the effects of gefitinib, an epidermal growth factor receptor inhibitor, on autophagy and HMGB1 release in BGC-823 cells. MTT assay and western blot analysis assessed the effects of extracellular HMGB1 on cell proliferation and signaling transduction. Released HMGB1 promoted proliferation through activation of ERK1/2 MAPK. HMGB1 expression in gastric cancer tissues and serum was significantly increased compared to the controls and healthy serum. Gastric carcinoma cells showed an increased HMGB1 in the nuclei and cytoplasm, whereas GES-1 cells exhibited a lower HMGB1 with nuclear localization. Gefitinib increased autophagy and cytoplasmic HMGB1 release from the BGC-823 cells. Extracellular HMGB1 in autophagic cell supernatant promoted proliferation that was abolished by glycyrrhizic acid, an HMGB1 inhibitor. BGC-823 cells incubated with HMGB1 had increased ERK1/2 phosphorylation, while levels of JNK, p38 or AKT were not affected. Blocking RAGE-HMGB1 interaction with antibody or siRNA suppressed the ERK1/2 activation and gastric cancer cell growth, indicating that RAGE-mediated ERK1/2 signaling was necessary for tumor progression.

High mobility group box 1 protein is methylated and transported to cytoplasm in clear cell renal cell carcinoma

BACKGROUND

The high mobility group box 1 (HMGB1) protein is a widespread nuclear protein present in most cell types. It typically locates in the nucleus and functions as a nuclear cofactor in transcription regulation. However, HMGB1 can also localize in the cytoplasm and be released into extracellular matrix, where it plays critical roles in carcinogenesis and inflammation. However, it remains elusive whether HMGB1 is relocated to cytoplasm in clear cell renal cell carcinoma (ccRCC).

METHODS

Nuclear and cytoplasmic proteins were extracted by different protocols from 20 ccRCC samples and corresponding adjacent renal tissues. Western blotting and immunohistochemistry were used to identify the expression of HMGB1 in ccRCC. To elucidate the potential mechanism of HMGB1 cytoplasmic translocation, HMGB1 proteins were enriched by immunoprecipitation and analyzed by mass spectrometry (MS).

RESULTS

The HMGB1 protein was overexpressed and partially localized in cytoplasm in ccRCC samples (12/20, 60%, p<0.05). Immunohistochemistry results indicated that ccRCC of high nuclear grade possess more HMGB1 relocation than those with low grade (p<0.05). Methylation of HMGB1 at lysine 112 in ccRCC was detected by MS. Bioinformatics analysis showed that post-translational modification might affect the binding ability to DNA and mediate its translocation.

CONCLUSION

Relocation of HMGB1 to cytoplasm was confirmed in ccRCC. Methylation of HMGB1 at lysine 112 might the redistribution of this cofactor protein.

Investigation of phosphoproteome in RAGE signaling

The receptor for advanced glycation end products (RAGE) is one of the most important proteins implicated in diabetes, cardiovascular diseases, neurodegenerative diseases, and cancer. It is a pattern recognition receptor by virtue of its ability to interact with multiple ligands, RAGE activates several signal transduction pathways through involvement of various kinases that phosphorylate their respective substrates. Only few substrates have been known to be phosphorylated in response to activation by RAGE (e.g., nuclear factor kappa B); however, it is possible that these kinases can phosphorylate multiple substrates depending upon their expression and localization, leading to altered cellular responses in different cell types and conditions. One such example is, glycogen synthase kinase 3 beta which is known to phosphorylate glycogen synthase, acts downstream to RAGE, and hyperphosphorylates microtubule-associated protein tau causing neuronal damage. Thus, it is important to understand the role of various RAGE-activated kinases and their substrates. Therefore, we have reviewed here the details of RAGE-activated kinases in response to different ligands and their respective phosphoproteome. Furthermore, we discuss the analysis of the data mined for known substrates of these kinases from the PhosphoSitePlus (http://www.phosphosite.org) database, and the role of some of the important substrates involved in cancer, diabetes, cardiovascular diseases, and neurodegenerative diseases. In summary, this review provides information on RAGE-activated kinases and their phosphoproteome, which will be helpful in understanding the possible role of RAGE and its ligands in progression of diseases.

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.

Cell migration is regulated by AGE-RAGE interaction in human oral cancer cells in vitro

Advanced glycation end products (AGEs) are produced in an irreversible non-enzymatic reaction of carbohydrates and proteins. Patients with diabetes mellitus (DM) are known to have elevated AGE levels, which is viewed as a risk factor of diabetes-related complications. In a clinical setting, it has been shown that patients with oral cancer in conjunction with DM have a higher likelihood of cancer metastasis and lower cancer survival rates. AGE-RAGE (a receptor of AGEs) is also correlated with metastasis and angiogenesis. Recent studies have suggested that the malignancy of cancer may be enhanced by glyceraldehyde-derived AGEs; however, the underlying mechanism remains unclear. This study examined the apparently close correlation between AGE-RAGE and the malignancy of SAS oral cancer cell line. In this study, AGEs increased ERK phosphorylation, enhanced cell migration, and promoted the expression of RAGE, MMP2, and MMP9. Using PD98059, RAGE antibody, and RAGE RNAi to block RAGE pathway resulted in the inhibition of ERK phosphorylation. Cell migration, MMP2 and MMP9 expression were also reduced by this treatment. Our findings demonstrate the importance of AGE-RAGE with regard to the malignancy of oral cancer, and help to explain the poor prognosis of DM subjects with oral cancer.

Pioglitazone, a PPARγ agonist, inhibits growth and invasion of human hepatocellular carcinoma via blockade of the rage signaling

Pioglitazone (PGZ), a synthetic PPARγ ligand, is known to have anti-tumor activity. However, it is unclear how it acts against hepatocellular carcinoma (HCC). We hypothesized that the pathological receptor for advanced glycation end products (RAGE) is involved in the PGZ anti-tumor process. To test this notion, human primary HCC tissues and corresponding adjacent non-cancerous tissues (ANCT) from 75 consecutive cases were analyzed. The expression and clinical significance of RAGE was assessed by immunohistochemical assay through tissue microarray. After HCC cells were pretreated with different concentrations of PGZ, cell proliferation, apoptosis, cell invasion, and cell cycle distribution were evaluated by multiple assays. The results showed that, the positive expression of RAGE was significantly higher in HCC tissues than in ANCT (66.7% vs. 36.0%, P < 0.001), and was closely associated with pathological staging (P = 0.014) and lymph-vascular space invasion (P = 0.003). Moreover, PGZ inhibited proliferative activity and invasive potential, and induced apoptosis and cell cycle arrest in HCC cells resulting in increased expression of PPARγ and decreased expression of RAGE, NF-κB, HMGB1, p38MAPK, Ki-67, MMP-2, and CyclinD1. Furthermore, knockdown of RAGE or NF-κB by siRNA effectively suppressed cell proliferation and invasion, and mediated the inhibitory effects of PGZ in HCC cells. Taken together, our findings suggest that, RAGE is overexpressed in human HCC tissues, and is closely associated with the pathological staging and tumor invasion of HCC. In addition, PGZ as a PPARγ agonist may inhibit growth and invasion of HCC cells via blockade of the RAGE signaling.

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.

Expression of RAGE and HMGB1 in thymic epithelial tumors, thymic hyperplasia and regular thymic morphology

Recently, a role of the receptor for advanced glycation endproducts (RAGE) in myasthenia gravis was described. RAGE and its ligand high mobility group box 1 (HMGB1) play key roles in autoimmunity and cancer. To test whether these molecules are involved in patients with thymic abnormalities we applied immunohistochemical analysis in 33 cases of thymic epithelial tumors, comprising 27 thymomas and 6 thymic carcinomas, and 21 nonneoplastic thymuses. Both molecules were detected in neoplastic epithelial cells: RAGE staining was most intense in WHO type B2 thymomas and thymic carcinomas (p<0.001). HMGB1 nuclear staining was strongest in A and AB, and gradually less in B1 = B2>B3>thymic carcinoma (p<0.001). Conversely, HMGB1 cytoplasmic staining intensities were as follows: A and AB (none), B1 (strong), B2 (moderate), B3 and thymic carcinoma (weak); (p<0.001). Fetal thymic tissue showed a distinct expression of RAGE and HMGB1 in subcapsular cortical epithelial cells which was found in 50% of myasthenic patients. Furthermore RAGE and HMGB1 were expressed in thymocytes, macrophages, Hassall's corpuscles, thymic medulla, and germinal center cells in myasthenic patients. Immunohistochemistry results were complemented by systemic measurements (immunosorbent assay): serum levels of soluble RAGE were significantly reduced in patients with epithelial tumors (p = 0.008); and in invasive tumors (p = 0.008). Whereas RAGE was equally reduced in thymic hyperplasia and epithelial tumors (p = 0.003), HMGB1 was only elevated in malignancies (p = 0.036). Results were most pronounced in thymic carcinomas. Thus, RAGE and HMGB1 are involved in the (patho-)physiology of thymus, as evidenced by differentiated thymic and systemic expression patterns that may act as diagnostic or therapeutic targets in autoimmune disease and cancer.

Receptor for Advanced Glycation Endproducts (RAGE), Its Ligands, and Soluble RAGE: Potential Biomarkers for Diagnosis and Therapeutic Targets for Human Renal Diseases

Receptor for advanced glycation endproducts (RAGE) is a multi-ligand receptor that is able to bind several different ligands, including advanced glycation endproducts, high-mobility group protein (B)1 (HMGB1), S-100 calcium-binding protein, amyloid-β-protein, Mac-1, and phosphatidylserine. Its interaction is engaged in critical cellular processes, such as inflammation, proliferation, apoptosis, autophagy, and migration, and dysregulation of RAGE and its ligands leads to the development of numerous human diseases. In this review, we summarize the signaling pathways regulated by RAGE and its ligands identified up to date and demonstrate the effects of hyper-activation of RAGE signals on human diseases, focused mainly on renal disorders. Finally, we propose that RAGE and its ligands are the potential targets for the diagnosis, monitoring, and treatment of numerous renal diseases.

Clinical significance of immunogenic cell death biomarker rage and early growth response 1 in human primary gastric adenocarcinoma

The receptor for advanced glycation end products (RAGE), a pattern recognition receptor that binds multiple ligands derived from a damaged cell environment, contributes to multiple pathologies including cancer. Early growth response 1 (EGR1) is a tumor suppressor gene or a tumor promoter involved in tumorigenesis and progression of some cancers. However, there is some lack of knowledge about the expression and clinical significance of RAGE and EGR1 in human primary gastric adenocarcinoma (GAC). The present study was aimed to investigate the expression and clinical significance of RAGE and EGR1 in human GAC. One hundred and twenty cases of GAC tissues, adjacent non-cancer tissues (ANCT) and metastatic lymph node (MLN) tissues were collected. The expression of RAGE and EGR1 was assessed using immunohistochemistry (IHC) through tissue microarray procedure. The clinicopathologic characteristics of all patients were analyzed. As a result, the expression of RAGE in GAC and MLN tissues showed the positive staining mainly in the cytoplasm, with lower reactivity rate compared with the ANCT (P less than 0.001), while EGR1 expression had no significant difference between GAC, MLN tissues and ANCT (P=0.565). Moreover, the positive expression of RAGE was closely associated with the N stage of GAC patients, but did not correlate with their age, gender, tumor size, tumor sites, T stage, and metastatic lymph node (each P>0.05). In addition, Spearman Rank correlation analysis showed the positive correlation of RAGE expression with EGR1 in GAC tissues (r=0.658). Taken together, the expression of RAGE is decreased in GAC and MLN tissues, and is associated with the N stage of GAC patients, suggesting that RAGE may represent a potential therapeutic target for the treatment of GAC.

IL-1β, RAGE and FABP4: targeting the dynamic trio in metabolic inflammation and related pathologies

Within the past decade, inflammatory and lipid mediators, such as IL-1β, FABP4 and RAGE, have emerged as important contributors to metabolic dysfunction. As growing experimental and clinical evidence continues to tie obesity-induced chronic inflammation with dysregulated lipid, insulin signaling and related pathologies, IL-1β, FABP4 and RAGE each are being independently implicated as culprits in these events. There are also convincing data that molecular pathways driven by these molecules are interconnected in exacerbating metabolic consequences of obesity. This article highlights the roles of IL-1β, FABP4 and RAGE in normal physiology as well as focusing specifically on their contribution to inflammation, insulin resistance, atherosclerosis, Type 2 diabetes and cancer. Studies implicating the interconnection between these pathways, current and emerging therapeutics, and their use as potential biomarkers are also discussed. Evidence of impact of IL-1β, FABP4 and RAGE pathways on severity of metabolic dysfunction underlines the strong links between inflammatory events, lipid metabolism and insulin regulation, and offers new intriguing approaches for future therapies of obesity-driven pathologies.

Dendritic cell-based immunotherapy in prevention and treatment of renal cell carcinoma: efficacy, safety, and activity of Ad-GM·CAIX in immunocompetent mouse models

The dendritic cell vaccine DC-Ad-GM·CAIX is an active, specific immunotherapy with the potential of providing a safe and effective therapy against renal cell carcinoma (RCC). Using immunocompetent Balb/c mouse models we tested the efficacy and mechanism of the vaccine to prevent and treat the growth of a syngeneic RCC (RENCA) engineered to overexpress the human TAA carbonic anhydrase IX (NPR-IX). In a prevention model, NPR-IX tumor development was specifically and significantly delayed by 13 days in DC-Ad-GM·CAIX-treated mice (P < 0.001), tumor volumes were 79% smaller (day 24, P < 0.007), and body weight was maintained at study termination compared with the controls. Six of these mice remained tumor-free for > 1 year. In a treatment model, NPR-IX tumors remained smaller in DC-Ad-GM·CAIX-treated mice for 8 days (P < 0.002), achieving a 60% growth inhibition at termination. No vaccine-related organ toxicity was observed in either model. The critical mechanistic parameter separating responsive from nonresponsive tumors was hCAIX protein expression, demonstrated by aggressive growth of tumors that did not express hCAIX protein and in sham-treated mice (DC-Ad-Null). No murine serum anti-hCAIX antibodies were detected. Moreover, altered mechanisms of immunoediting as a means for immune evasion were suggested by differential gene expression (Ccl1, Hmgb1, Fgl2, Cd209a, and Klra2) and therapy evasion miRNAs (miR-1186, miR-98, miR-5097, miR-1942, and miR-708) in tumors that evaded DC-Ad-GM·CAIX immunotherapy. This is the first study in immunocompetent mice that provides a proof of concept for the specificity, efficacy, safety, and activity of the DC-Ad-GM·CAIX immunotherapy, forming the basis for a first-in-human phase I trial in RCC patients.

Ethyl pyruvate administration suppresses growth and invasion of gallbladder cancer cells via downregulation of HMGB1-RAGE axis

High mobility group box B1 (HMGB1)-receptor for advanced glycation end products (RAGE) axis has been previously known to be involved in carcinogenesis and development of multiple malignancies. Some studies have confirmed that Ethyl pyruvate (EP), a potent inhibitor of HMGB1, exerts the therapeutic effects on metastatic live tumor from gastric cancer. However, the effects and possible molecular mechanisms of EP on gallbladder cancer (GBC) need to be further explored. In the present study, human GBC cell lines (GBC-SD and SGC-996) were treated with different concentrations of EP. Then, the expression levels of HMGB1, RAGE and some transcription factors were identified by Real-time PCR and Western blot assays. Cell proliferative activities indicated by MTT assay, invasive potential by Transwell assay and cell apoptosis and cycle distribution were performed for functional analysis of GBC cell lines in vitro. As a result, EP decreased the expression of HMGB11, RAGE, PCNA and matrix metallopeptidase-9 (MMP-9), while it increased the expression of p53. Moreover, EP administration decreased GBC cell proliferation, inhibited the invasive potential, and induced apoptosis and cycle arrest in S phase in GBC cells. In conclusion, EP administration inhibits growth and invasion of gallbladder cancer cells possibly via down-regulation of the HMGB1-RAGE axis, suggesting that EP may play a critical role in the treatment of cancer in conjunction with other therapeutic agents.

Specific siRNA targeting receptor for advanced glycation end products (RAGE) decreases proliferation in human breast cancer cell lines

Receptor for Advanced Glycation End Products (RAGE) is an oncogenic trans-membranous receptor overexpressed in various human cancers. However, the role of RAGE in breast cancer development and proliferation is still unclear. In this study, we demonstrated that RAGE expression levels are correlated to the degree of severity of breast cancer. Furthermore, there is a decrease in the proliferation of all sub-types of breast cancer, MCF-7, SK-Br-3 and MDA-MB-231, as a result of the effect of RAGE siRNA. RAGE siRNA arrested cells in the G1 phase and inhibited DNA synthesis (p < 0.05). Moreover, qRT-PCR and Western Blot results demonstrated that RAGE siRNA decreases the expression of transcriptional factor NF-κB p65 as well as the expression of cell proliferation markers PCNA and cyclinD1. RAGE and RAGE ligands can thus be considered as possible targets for breast cancer management and therapy.

High mobility group box 1 and kidney diseases (Review)

High mobility group box 1 (HMGB1), a non-histone DNA-binding protein, regulates nucleosome function and transcription in the nuclei of all metazoans and plants. However, extracellular HMGB1, which is actively or passively released under different conditions, can act as a key inflammatory mediator through MyD88/mitogen-activated protein kinase signaling by binding to its receptors including the receptor for advanced glycation end products or Toll-like receptors. A growing body of evidence indicates that HMGB1 plays an important role in kidney diseases, such as glomerulonephritis, lupus nephritis, antineutrophilic cytoplasmatic antibody-associated vaculitis, diabetic nephropathy, renal allograft rejection and acute kidney injury. In this review, we focus on the biology of HMGB1 and the association of HMGB1 with kidney diseases.

Expression and clinical significance of HMGB1 in human liver cancer: Knockdown inhibits tumor growth and metastasis in vitro and in vivo

The high-mobility group box 1 (HMGB1) signaling pathway plays a crucial role in tumorigenesis and progression of many malignant cancers. The present study aimed to investigate the expression and clinical significance of HMGB1 in human primary liver cancer, and further explore the molecular mechanisms of HMGB1 in tumor growth and metastasis. Forty cases of human liver cancer and normal liver tissues were collected. The expression of HMGB1 was assessed using RT-PCR and western blot assays in biopsy samples. The HMGB1 pathway in vitro was blocked using transfection of the recombinant small hairpin RNA adenovirus vector rAd5-HMGB1 into the human liver cancer cell line SMMC-7721. The expression of HMGB1, phosphorylated AKT (p-AKT), Ki-67 and matrix metallopeptidase-2 (MMP-2) was detected by Real-PCR and western blot assays. Cell proliferative activities and metastatic capability were determined by MTT and Transwell assays. Cell cycle distribution and apoptosis were detected by flow cytometry. A subcutaneous xenograft tumor model was established, validating the effects of rAd5-HMGB1 on tumor growth in vivo. As a consequence, HMGB1 was found to be highly expressed in liver cancer compared with normal tissues, and was positively associated with pathological grade and distant metastases of liver cancer. Knockdown of HMGB1 downregulated the expression of p-AKT, Ki-67 and MMP-2, inhibited the proliferative activities and metastatic potential of SMMC-7721 cells, induced cell cycle arrest and apoptosis, and slowed the growth of xenograft tumors. Altogether, the expression of HMGB1 is closely correlated with pathological grade and distant metastases of liver cancer, and knockdown of HMGB1 inhibits liver cancer growth and metastasis, suggesting that HMGB1 may be involved in liver cancer development and progression through AKT-mediated regulation of Ki-67 and MMP-2 expression, and represent a potential therapeutic target for this aggressive malignancy.

Gut microbiota, immune development and function

The microbiota of Westerners is significantly reduced in comparison to rural individuals living a similar lifestyle to our Paleolithic forefathers but also to that of other free-living primates such as the chimpanzee. The great majority of ingredients in the industrially produced foods consumed in the West are absorbed in the upper part of small intestine and thus of limited benefit to the microbiota. Lack of proper nutrition for microbiota is a major factor under-pinning dysfunctional microbiota, dysbiosis, chronically elevated inflammation, and the production and leakage of endotoxins through the various tissue barriers. Furthermore, the over-comsumption of insulinogenic foods and proteotoxins, such as advanced glycation and lipoxidation molecules, gluten and zein, and a reduced intake of fruit and vegetables, are key factors behind the commonly observed elevated inflammation and the endemic of obesity and chronic diseases, factors which are also likely to be detrimental to microbiota. As a consequence of this lifestyle and the associated eating habits, most barriers, including the gut, the airways, the skin, the oral cavity, the vagina, the placenta, the blood-brain barrier, etc., are increasingly permeable. Attempts to recondition these barriers through the use of so called 'probiotics', normally applied to the gut, are rarely successful, and sometimes fail, as they are usually applied as adjunctive treatments, e.g. in parallel with heavy pharmaceutical treatment, not rarely consisting in antibiotics and chemotherapy. It is increasingly observed that the majority of pharmaceutical drugs, even those believed to have minimal adverse effects, such as proton pump inhibitors and anti-hypertensives, in fact adversely affect immune development and functions and are most likely also deleterious to microbiota. Equally, it appears that probiotic treatment is not compatible with pharmacological treatments. Eco-biological treatments, with plant-derived substances, or phytochemicals, e.g. curcumin and resveratrol, and pre-, pro- and syn-biotics offers similar effects as use of biologicals, although milder but also free from adverse effects. Such treatments should be tried as alternative therapies; mainly, to begin with, for disease prevention but also in early cases of chronic diseases. Pharmaceutical treatment has, thus far, failed to inhibit the tsunami of endemic diseases spreading around the world, and no new tools are in sight. Dramatic alterations, in direction of a paleolithic-like lifestyle and food habits, seem to be the only alternatives with the potential to control the present escalating crisis. The present review focuses on human studies, especially those of clinical relevance.