The expression of HMGB1 protein and its receptor RAGE in human malignant tumors

The immune mechanisms of abscopal effect in radiation therapy

Radiation therapy (RT) is a cornerstone in oncologic management and is employed in various curative and palliative scenarios for local-regional control. RT is thought to locally control tumor cells by direct physical DNA damage or indirect insults from reactive oxygen species. Therapeutic effects apart from those observed at the treatment target, that is, abscopal effect, have been observed for several decades, though the underlying mechanisms regulating this phenomenon have been unclear. Accumulating evidence now suggests that the immune system is a major determinant in regulating the abscopal effect. It is now evident that RT may also enhance immunologic responses to tumors by creating an in situ vaccine by eliciting antigen release from dying tumor cells. Harnessing the specificity and dynamic nature of the immune system to target tumors in conjunction with RT is an emerging field with much promise. To optimize this approach, it is important to systematically evaluate the intricacies of the host immune system, the new generation of immunotherapeutics and the RT approach. Here we will discuss the current biologic mechanisms thought to regulate the RT-induced abscopal effect and how these may be translated to the clinical setting.

Potential role of High mobility group box 1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide and is characterized as a typical inflammation-related carcinoma. High mobility group box protein 1 (HMGB1), a non-histone DNA-binding protein, is identified as a potent proinflammatory mediator when presents extracellularly. Recently, a growing body of evidence indicates that HMGB1 plays a potential role in HCC, but many questions remain unanswered about the relationship between HMGB1 and HCC formation and development. This review focuses on the biological effect of HMGB1, and discusses the association of HMGB1 with HCC and potential use of strategies targeting HMGB1 in HCC treatment.

The Role of HMGB1 Signaling Pathway in the Development and Progression of Hepatocellular Carcinoma: A Review

The story of high mobility group protein B1 (HMGB1) in cancer is complicated and the function of HMGB1 in different cancers is uncertain. This review aims to retrieve literature regarding HMGB1 from English electronic resources, analyze and summarize the role of the HMGB1 signaling pathway in hepatocellular carcinoma (HCC), and provide useful information for carcinogenesis and progression of HCC. Results showed that HMGB1 could induce cell proliferation, differentiation, cell death, angiogenesis, metastasis, inflammation, and enhance immunofunction in in vitro and in vivo HCC models. HMGB1 and its downstream receptors RAGE, TLRs and TREM-1 may be potential anticancer targets. In conclusion, HMGB1 plays an important role in oncogenesis and represents a novel therapeutic target, which deserves further study.

High‑mobility group box 1 has a prognostic role and contributes to epithelial mesenchymal transition in human hepatocellular carcinoma

High‑mobility group box 1 (HMGB1), a member of the high‑mobility group protein family, was originally characterized as a non‑histone, nuclear DNA‑binding protein. While the roles of HMGB1 in inflammation and cell differentiation have been previously reported, its role in tumor cell migration and invasion, particularly in hepatocellular carcinoma (HCC), has remained elusive. The present study reported that the expression of HMGB1 in HCC tissues was significantly higher than that in matched tumor‑adjacent tissues (P<0.05). HMGB1 was expressed at significantly elevated levels in tumors of patients with large tumor size, high histological grade and advanced tumor‑node‑metastasis stage (P<0.05). The positive expression of HMGB1 correlated with a poor three‑year overall and disease‑free survival of HCC patients (P<0.05). In addition, HMGB1 was an independent factor for predicting the three‑year overall and disease‑free survival of HCC patients (P<0.05). An in vitro experiment revealed that knockdown of HMGB1 inhibited cell migration and invasion in the HCC cell lines Huh7 and MHCC97H (P<0.05). Furthermore, western blot analysis showed that HMGB1 knockdown markedly inhibited epithelial mesenchymal transition in Huh7 and MHCC97H cells. These results suggested that HMGB1 may be utilized as an independent prognostic marker in HCC and may promote tumor progression by promoting cell migration and invasion.

Pathway-based gene signatures predicting clinical outcome of lung adenocarcinoma

Lung adenocarcinoma is often diagnosed at an advanced stage with poor prognosis. Patients with different clinical outcomes may have similar clinico-pathological characteristics. The results of previous studies for biomarkers for lung adenocarcinoma have generally been inconsistent and limited in clinical application. In this study, we used inverse-variance weighting to combine the hazard ratios for the four datasets and performed pathway analysis to identify prognosis-associated gene signatures. A total of 2,418 genes were found to be significantly associated with overall survival. Of these, a 21-gene signature in the HMGB1/RAGE signalling pathway and a 31-gene signature in the clathrin-coated vesicle cycle pathway were significantly associated with prognosis of lung adenocarcinoma across all four datasets (all p-values < 0.05, log-rank test). We combined the scores for the three pathways to derive a combined pathway-based risk (CPBR) score. Three pathway-based signatures and CPBR score also had more predictive power than single genes. Finally, the CPBR score was validated in two independent cohorts (GSE14814 and GSE13213 in the GEO database) and had significant adjusted hazard ratios 2.72 (p-value < 0.0001) and 1.71 (p-value < 0.0001), respectively. These results could provide a more complete picture of the lung cancer pathogenesis.

CEMP1 Induces Transformation in Human Gingival Fibroblasts

Cementum Protein 1 (CEMP1) is a key regulator of cementogenesis. CEMP1 promotes cell attachment, differentiation, deposition rate, composition, and morphology of hydroxyapatite crystals formed by human cementoblastic cells. Its expression is restricted to cementoblasts and progenitor cell subpopulations present in the periodontal ligament. CEMP1 transfection into non-osteogenic cells such as adult human gingival fibroblasts results in differentiation of these cells into a “mineralizing” cell phenotype. Other studies have shown evidence that CEMP1 could have a therapeutic potential for the treatment of bone defects and regeneration of other mineralized tissues. To better understand CEMP1’s biological effects in vitro we investigated the consequences of its expression in human gingival fibroblasts (HGF) growing in non-mineralizing media by comparing gene expression profiles. We identified several mRNAs whose expression is modified by CEMP1 induction in HGF cells. Enrichment analysis showed that several of these newly expressed genes are involved in oncogenesis. Our results suggest that CEMP1 causes the transformation of HGF and NIH3T3 cells. CEMP1 is overexpressed in cancer cell lines. We also determined that the region spanning the CEMP1 locus is commonly amplified in a variety of cancers, and finally we found significant overexpression of CEMP1 in leukemia, cervix, breast, prostate and lung cancer. Our findings suggest that CEMP1 exerts modulation of a number of cellular genes, cellular development, cellular growth, cell death, and cell cycle, and molecules associated with cancer.

Overexpression of the Receptor for Advanced Glycation Endproducts (RAGE) is associated with poor prognosis in gastric cancer

BACKGROUND

The receptor for advanced glycation endproducts (RAGE) is an oncogenic multidisciplinary trans-membranous receptor, which is overexpressed in multiple human cancers. Recently, it has been shown that RAGE is also involved in carcinogenesis and tumor invasion. In this study, we investigated the expression levels and prognostic value of RAGE in primary gastric cancers (GC).

METHODS

We investigated RAGE expression in primary GC and paired normal gastric tissue by real-time quantitative RT-PCR (n = 30) and Western blotting analysis (n = 30). Additionally, we performed immunohistochemistry on 180 paraffin-embedded GC specimens, 69 matched normal specimens.

RESULTS

RAGE was overexpressed in GC compared with the adjacent noncancerous tissues (P＜0.001), and higher RAGE expression significantly correlated with the histological grade (P = 0.002), nodal status(P = 0.025), metastasis status(P = 0.002), and American Joint Committee on Cancer stage (P = 0.020). Furthermore, upregulation of RAGE expression is an independent prognostic factor in multivariate analysis using the Cox regression model (P = 0.001).

CONCLUSIONS

RAGE Overexpression may be a useful marker to predict GC progression and poor prognosis.

High mobility group box-1 and its clinical value in breast cancer

BACKGROUND

High mobility group box-1 (HMGB1) is a factor regulating malignant tumorigenesis, proliferation, and metastasis, and is associated with poor clinical pathology in various human cancers. We investigated the differential concentrations of HMGB1 in tissues and sera, and their clinical value for diagnosis in patients with breast cancer, benign breast disease, and healthy individuals.

METHODS

HMGB1 levels in tumor tissues, adjacent normal tissues, and benign breast disease tissues was detected via immunohistochemistry. Serum HMGB1 was measured using an enzyme-linked immunosorbent assay in 56 patients with breast cancer, 25 patients with benign breast disease, and 30 healthy control subjects. The clinicopathological features of the patients were compared. Tissues were evaluated histopathologically by pathologists.

RESULTS

HMGB1 levels in the tissues and sera of patients with breast cancer were significantly higher than those in patients with benign breast disease or normal individuals. The 56 cancer patients were classified as having high tissue HMGB1 levels (n=41) or low tissue HMGB1 levels (n=15), but the corresponsive serum HMGB1 in these two groups was not significantly different. HMGB1 levels in breast cancer tissues significantly correlated with differentiation grade, lymphatic metastasis, and tumor-node-metastasis stage, but not patient age, tumor size, or HER-2/neu expression; no association between serum HMGB1 levels and these clinicopathological parameters was found. The sensitivity and specificity of tissue HMGB1 levels for the diagnosis of breast cancer were 73.21% and 84.00%, respectively, while positive and negative predictive values were 91.11% and 58.33%.

CONCLUSION

HMGB1 might be involved in the development and progression of breast cancer and could be a supportive diagnostic marker for breast cancer. Serum HMGB1 could be a useful serological biomarker for diagnosis and screening of breast cancer.

Cancer-associated fibroblasts induce high mobility group box 1 and contribute to resistance to doxorubicin in breast cancer cells

Background

Cancer-associated fibroblasts and high mobility group box 1 (HMGB1) protein have been suggested to mediate cancer progression and chemotherapy resistance. The role of such fibroblasts in HMGB1 production in breast cancer is unclear. This study aimed to investigate the effects of cancer-associated fibroblasts on HMGB1 expression in breast cancer cells and its role in chemotherapeutic response.

Methods

Breast cancer-associated fibroblasts (BCFs) and non-tumor-associated fibroblasts (NTFs) were isolated from human breast cancers or adjacent normal tissues and established as primary cultures in vitro. After confirmation of the activated status of these fibroblasts, conditioned-media (CM) were collected and applied to MDA-MB-231 human triple negative breast cancer cells. The levels of intracellular and extracellular HMGB1 were measured by real-time PCR and/or Western blot. The response of BCF-CM-pre-treated cancer cells to doxorubicin (Dox) was compared with those pre-treated with NTF-CM or control cultures. The effect of an HMGB1 neutralizing antibody on Dox resistance induced by extracellular HMGB1 from non-viable Dox-treated cancer cells or recombinant HMGB1 was also investigated.

Results

Immunocytochemical analysis revealed that BCFs and NTFs were alpha-smooth muscle actin (ASMA) positive and cytokeratin 19 (CK19) negative cells: a phenotype consistent with that of activated fibroblasts. We confirmed that the CM from BCFs (but not NTFs), could significantly induce breast cancer cell migration. Intracellular HMGB1 expression was induced in BCF-CM-treated breast cancer cells and also in Dox-treated cells. Extracellular HMGB1 was strongly expressed in the CM after Dox-induced MDA-MB-231 cell death and was higher in cells pre-treated with BCF-CM than NTF-CM. Pre-treatment of breast cancer cells with BCF-CM induced a degree of resistance to Dox in accordance with the increased level of secreted HMGB1. Recombinant HMGB1 was shown to increase Dox resistance and this was associated with evidence of autophagy. Anti-HMGB1 neutralizing antibody significantly reduced the effect of extracellular HMGB1 released from dying cancer cells or of recombinant HMGB1 on Dox resistance.

Conclusions

These findings highlight the potential of stromal fibroblasts to contribute to chemoresistance in breast cancer cells in part through fibroblast-induced HMGB1 production.

Association of Upregulated HMGB1 and c-IAP2 Proteins With Hepatocellular Carcinoma Development and Progression

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most important health problems in China.

OBJECTIVES

This study analyzed expression of high-mobility group protein B1 (HMGB1) and inhibitor of apoptosis protein-2 (c-IAP2) proteins in HCC compared to paired para-tumor tissue samples to assess the association with HCC pathogenesis and progression.

MATERIALS AND METHODS

Sixty-eight HCC and para-tumor tissue samples were collected for Western blot, qRT-PCR and immunohistochemical analyses of HMGB1 and c-IAP2.

RESULTS

HMGB1 and c-IAP2 proteins were highly expressed in HCC tissue samples [85.3% (58/68) and 82.4% (56/68), respectively] compared to para-tumor tissue samples [32.3% and 27.9%, respectively]. Furthermore, expression of HMGB1 was significantly associated with enhanced c-IAP2 expression in HCC tissue samples (r = 0.878, P < 0.01). Expression of HMGB1 was associated with tumor multiplicity and size, alpha-fetoprotein (AFP) level and advanced TNM stage, while expression of c-IAP2 was associated with tumor size, AFP level and advanced TNM stage.

CONCLUSIONS

Expression of HMGB1 and c-IAP2 proteins was associated with HCC development and progression, and the expression of HMGB1 and c-IAP2 proteins in HCC were significantly associated with each other. Additionally, these proteins may show promise as biomarkers to predict HCC progression.

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.

Clinical and prognostic significance of high-mobility group box-1 in human gliomas

The objective of this study was to explore the expression and the clinical and prognostic significance of high-mobility group box-1 (HMGB1) in human gliomas. The expression of HMGB1 in 15 samples of normal brain tissue and 65 samples of different-grade glioma tissue was assayed using immunohistochemistry and western blot analysis. The associations between the differences in expression and pathology grades were analyzed statistically. Uni- and multivariate analyses were performed to investigate the prognostic value of HMGB1 expression and its expression levels. The positive rates of HMGB1 expression in normal brain and glioma tissue were 20.0% (3/15) and 76.9% (50/65), respectively. The expression of HMGB1 in glioma tissue was higher than that in normal tissue (P<0.05). The positive rates of HMGB1 expression in low-grade gliomas (LGGs, grades I and II) and high-grade gliomas (HGGs, grades III and IV) were 63.0% (17/27) and 86.8% (33/38), respectively, and the positive rates in HGG were higher than those in LGG (P=0.024). Western blot analysis showed that HMGB1 was also expressed in normal brain tissue. The expression levels in HGG were significantly higher than those in LGG (P<0.001). HMGB1-positive patients had significantly shorter overall survival times compared with HMGB1-negative patients (P=0.026). Increasing levels of HMGB1 expression significantly correlated with reduced survival times when all patients with glioma were considered (P=0.045). In conclusion, HMGB1 positivity and protein expression levels are of significant clinical and prognostic value in human gliomas. Detecting HMGB1 in human gliomas may be useful for assessing the degree of malignancy, and HMGB1 would appear to be a promising target in the clinical management of patients with glioma.

The combination of a nuclear HMGB1-positive and HMGB2-negative expression is potentially associated with a shortened survival in patients with pancreatic ductal adenocarcinoma

High-mobility group box (HMGB) proteins are ubiquitous, abundant nuclear non-histone chromosomal proteins that play a critical role in binding to distorted DNA structures and subsequently regulating DNA transcription, replication, repair, and recombination. Both HMGB1 and HMGB2 exhibit a high expression in several human cancers and are closely associated with tumor progression and a poor prognosis. However, the expression patterns of these molecules in pancreatic ductal adenocarcinoma (PDAC) remain to be elucidated. As most cases of postoperative relapse of PDAC occur within the first 2 years, the clinical significance of accurate biomarkers is needed. Therefore, we investigated the correlation between the immunohistochemical HMGB1 and HMGB2 expression and the clinicopathological characteristics and prognosis using 62 paraffin-embedded tumor samples obtained from patients with surgically resected PDAC. The HMGB1/2 expression was considered to be positive when 10 % or more of the cancer cells showed positive nuclear, not merely cytoplasmic, staining. Consequently, the expression of HMGB1/2 was observed in 54 (87.1 %) and 31 (50.0 %) patients, respectively. Unexpectedly, a positive HMGB1 expression was found to have a significantly close relationship with a negative HMGB2 expression. The univariate and multivariate analyses demonstrated that the patients with a HMGB1+ and HMGB2- status had markedly lower disease-specific survival rates, especially within the first 2 years postoperatively, whereas those with a HMGB1+ status alone did not. Therefore, the combination of a HMGB1+ and HMGB2- expression potentially predicts a poor prognosis in patients with PDAC, and these new biomarkers may be useful parameters for clinical management in the early postoperative phase.

DNAX-activating protein 10 (DAP10) membrane adaptor associates with receptor for advanced glycation end products (RAGE) and modulates the RAGE-triggered signaling pathway in human keratinocytes

The receptor for advanced glycation end products (RAGE) is involved in the pathogenesis of many inflammatory, degenerative, and hyperproliferative diseases, including cancer. Previously, we revealed mechanisms of downstream signaling from ligand-activated RAGE, which recruits TIRAP/MyD88. Here, we showed that DNAX-activating protein 10 (DAP10), a transmembrane adaptor protein, also binds to RAGE. By artificial oligomerization of RAGE alone or RAGE-DAP10, we found that RAGE-DAP10 heterodimer formation resulted in a marked enhancement of Akt activation, whereas homomultimeric interaction of RAGE led to activation of caspase 8. Normal human epidermal keratinocytes exposed to S100A8/A9, a ligand for RAGE, at a nanomolar concentration mimicked the pro-survival response of RAGE-DAP10 interaction, although at a micromolar concentration, the cells mimicked the pro-apoptotic response of RAGE-RAGE. In transformed epithelial cell lines, A431 and HaCaT, in which endogenous DAP10 was overexpressed, and S100A8/A9, even at a micromolar concentration, led to cell growth and survival due to RAGE-DAP10 interaction. Functional blocking of DAP10 in the cell lines abrogated the Akt phosphorylation from S100A8/A9-activated RAGE, eventually leading to an increase in apoptosis. Finally, S100A8/A9, RAGE, and DAP10 were overexpressed in the psoriatic epidermis. Our findings indicate that the functional interaction between RAGE and DAP10 coordinately regulates S100A8/A9-mediated survival and/or apoptotic response of keratinocytes.

Suppression of toll-like receptor 2 expression inhibits the bioactivity of human hepatocellular carcinoma

Toll-like receptor (TLR) 2 signaling is regarded as one of the mechanisms of chronic inflammation, but it can also mediate tumor cell immune escape and tumor progression. However, the role of TLR2 in the progression of human hepatocellular carcinoma (HCC) remains unclear. The objective of the study was to examine the effect of TLR2 on the bioactivity of HCC cell lines, HepG2 and BEL-7402, and the relationship between high mobility group box1 (HMGB1) and TLR2. The expression of TLR2 and nuclear factor-kappaB/P65 (NF-κB/P65) in HepG2 and BEL-7402 was assayed by Western blot. Cells were transfected with specific small interfering RNAs of TLR2 (TLR2-siRNAs), then TLR2-siRNA-transfected cells were treated with recombinant HMGB1 (rHMGB1). Apoptosis was determined by flow cytometry. Results showed that TLR2 was expressed in HepG2 and BEL-7402 cells. The ability of proliferation, invasion, and migration in siRNA group was lower than that in blank group, and the apoptosis ratio was higher than that in blank group, respectively. NF-κB/P65 expression was declined in contrast with blank group. Downregulation of TLR2 by siRNA resulted in a significant inhibition of proliferation, invasion, migration, and NF-κB/P65 expression, and elevated apoptotic ratio. Conversely, rHMGB1 promoted proliferation, invasion, and migration, induced NF-κB/P65 expression, and inhibited cells apoptosis. Furthermore, downregulation of TLR2 weakened the role of rHMGB1. This study suggests TLR2 and HMGB1 are important targets for therapeutic intervention of HCC.

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.

Deregulation of the circadian clock constitutes a significant factor in tumorigenesis: a clockwork cancer. Part I: clocks and clocking machinery

Many physiological processes occur in a rhythmic fashion, consistent with a 24-h cycle. The central timing of the day/night rhythm is set by a master clock, located in the suprachiasmatic nucleus (a tiny region in the hypothalamus), but peripheral clocks exist in different tissues, adjustable by cues other than light (temperature, food, hormone stimulation, etc.), functioning autonomously to the master clock. Presence of unrepaired DNA damage may adjust the circadian clock so that the phase in which checking for damage and DNA repair normally occurs is advanced or extended. The expression of many of the genes coding for proteins functioning in DNA damage-associated response pathways and DNA repair is directly or indirectly regulated by the core clock proteins. Setting up the normal rhythm of the circadian cycle also involves oscillating changes in the chromatin structure, allowing differential activation of various chromatin domains within the 24-h cycle.

The association of HMGB1 gene with the prognosis of HCC

High-mobility group box 1 protein (HMGB1) is an evolutionarily ancient and critical regulator of cell death and survival. HMGB1 is a chromatin-associated nuclear protein molecule that triggers extracellular damage. The expression of HMGB1 has been reported in many types of cancers, but the role of HMGB1 in hepato cellular carcinoma (HCC) is unknown.The aim of this study was to analyze the roles of HMGB1 in HCC progression using HCC clinical samples. We also investigated the clinical outcomes of HCC samples with a special focus on HMBG1 expression. In an immunohistochemical study conducted on 208 cases of HCC, HMGB1 had high expression in 134 cases(64.4%).The HMGB1 expression level did not correlate with any clinicopathological parameters, except alpha fetoprotein (AFP) (p = 0.041) and CLIP stage (p = 0.007). However, survival analysis showed that the group with HMBG1 overexpression had a significantly shorter overall survival time than the group with a down-regulatedexpression of HMBG1 (HR = 0.568, CI (0.398, 0.811), p = 0.002). Multivariate analysis showed that HMGB1 expression was a significant and independent prognostic parameter (HR = 0.562, CI (0.388, 0.815), p = 0.002) for HCC patients. The ability of proliferation, migration and invasion of HCC cells was suppressed with the disruption of endogenous HMGB1 using small interfering RNAs. On the other hand, the ability of proliferation, migration and invasion of HCC cells was strengthened when the expression endogenous HMGB1 was enhanced using HMGB1 DNA. HMGB1 expression may be a novel and independent predictor for the prognosis of HCC patients. The overexpression of HMGB1 in HCC could be a novel, effective, and supplementary biomarker for HCC, since it plays a vital role in the progression of HCC.

A high M1/M2 ratio of tumor-associated macrophages is associated with extended survival in ovarian cancer patients

BACKGROUND

Tumor-associated macrophages (TAMs) are classified into two major phenotypes, M1 and M2. M1 TAMs suppress cancer progression, while M2 TAMs promote it. However, little is known regarding the role of TAMs in the development of ovarian cancer. Here, we investigated the relationship between TAM distribution patterns (density, microlocalization, and differentiation) and ovarian cancer histotypes, and we explored whether altered TAM distribution patterns influence long-term outcomes in ovarian cancer patients.

METHODS

A total of 112 ovarian cancer patients were enrolled in this study, and the subjects were divided into two groups according to their survival (< 5 years vs. ≥ 5 years). Immunohistochemistry and immunofluorescence were used to determine the density, microlocalization, and differentiation status of TAMs in ovarian cancer tissues for each histotype. Kaplan-Meier survival and multivariate Cox regression analyses were used to evaluate the prognostic significance of TAM-related parameters in ovarian cancer.

RESULTS

TAMs most frequently infiltrated into the cancer tissue of the serous histotype, followed by mucinous, undifferentiated, endometrioid, and clear cell histotypes (p = 0.049). The islet/stroma ratio of total TAMs varied among the cancer histotypes, with mucinous and undifferentiated cancers displaying the lowest and highest ratios, respectively (p = 0.005). The intratumoral TAM density significantly increased with increasing cancer stage and grade (p = 0.023 and 0.006, respectively). However, the overall M1/M2 TAM ratio decreased as the cancer stage increased (p = 0.012). In addition, the intra-islet M1/M2 ratio inversely correlated with the residual site size (p = 0.004). Among the TAM-related parameters, only the increased overall and intra-islet M1/M2 TAM ratios displayed prognostic significance in both the Kaplan-Meier survival and multivariate Cox regression analyses; however, the values of these two parameters did not differ significantly among the cancer histotypes.

CONCLUSIONS

The patients with increased overall or intra-islet M1/M2 TAM ratios presented with an improved 5-year prognosis. Nevertheless, the TAM distribution patterns did not influence the overall outcomes of different ovarian cancer histotypes.

Integrative genomic analysis identifies epigenetic marks that mediate genetic risk for epithelial ovarian cancer

BACKGROUND

Both genetic and epigenetic factors influence the development and progression of epithelial ovarian cancer (EOC). However, there is an incomplete understanding of the interrelationship between these factors and the extent to which they interact to impact disease risk. In the present study, we aimed to gain insight into this relationship by identifying DNA methylation marks that are candidate mediators of ovarian cancer genetic risk.

METHODS

We used 214 cases and 214 age-matched controls from the Mayo Clinic Ovarian Cancer Study. Pretreatment, blood-derived DNA was profiled for genome-wide methylation (Illumina Infinium HumanMethylation27 BeadArray) and single nucleotide polymorphisms (SNPs, Illumina Infinium HD Human610-Quad BeadArray). The Causal Inference Test (CIT) was implemented to distinguish CpG sites that mediate genetic risk, from those that are consequential or independently acted on by genotype.

RESULTS

Controlling for the estimated distribution of immune cells and other key covariates, our initial epigenome-wide association analysis revealed 1,993 significantly differentially methylated CpGs that between cases and controls (FDR, q < 0.05). The relationship between methylation and case-control status for these 1,993 CpGs was found to be highly consistent with the results of previously published, independent study that consisted of peripheral blood DNA methylation signatures in 131 pretreatment cases and 274 controls. Implementation of the CIT test revealed 17 CpG/SNP pairs, comprising 13 unique CpGs and 17 unique SNPs, which represent potential methylation-mediated relationships between genotype and EOC risk. Of these 13 CpGs, several are associated with immune related genes and genes that have been previously shown to exhibit altered expression in the context of cancer.

CONCLUSIONS

These findings provide additional insight into EOC etiology and may serve as novel biomarkers for EOC susceptibility.

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.

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.

Knockdown of RAGE inhibits growth and invasion of gastric cancer cells

The receptor for advanced glycation endproducts (RAGE) is an oncogenic trans-membranous receptor, which is overexpressed in multiple human cancers. However, the role of RAGE in gastric cancer is still elusive. In this study, we investigated the expression and molecular mechanisms of RAGE in gastric cancer cells. Forty cases of gastric cancer and corresponding adjacent non-cancerous tissues (ANCT) were collected, and the expression of RAGE was assessed using immunohistochemistry (IHC) in biopsy samples. Furthermore, RAGE signaling was blocked by constructed recombinant small hairpin RNA lentiviral vector (Lv-shRAGE) used to transfect into human gastric cancer SGC-7901 cells. The expression of AKT, proliferating cell nuclear antigen (PCNA) and matrix metallopeptidase-2 (MMP-2) was detected by Real-time PCR and Western blot assays. Cell proliferative activities and invasive capability were respectively determined by MTT and Transwell assays. Cell apoptosis and cycle distribution were analyzed by flow cytometry. As a consequence, RAGE was found highly expressed in cancer tissues compared with the ANCT (70.0% vs 45.0%, P=0.039), and correlated with lymph node metastases (P=0.026). Knockdown of RAGE reduced cell proliferation and invasion of gastric cancer with decreased expression of AKT, PCNA and MMP-2, and induced cell apoptosis and cycle arrest. Altogether, upregulation of RAGE expression is associated with lymph node metastases of gastric cancer, and blockade of RAGE signaling suppresses growth and invasion of gastric cancer cells through AKT pathway, suggesting that RAGE may represent a potential therapeutic target for this aggressive malignancy.

Emerging role of high-mobility group box 1 (HMGB1) in liver diseases

Damage-associated molecular pattern (DAMP) molecules are essential for the initiation of innate inflammatory responses to infection and injury. The prototypic DAMP molecule, high-mobility group box 1 (HMGB1), is an abundant architectural chromosomal protein that has location-specific biological functions: within the nucleus as a DNA chaperone, within the cytosol to sustain autophagy and outside the cell as a DAMP molecule. Recent research indicates that aberrant activation of HMGB1 signaling can promote the onset of inflammatory and autoimmune diseases, raising interest in the development of therapeutic strategies to control their function. The importance of HMGB1 activation in various forms of liver disease in relation to liver damage, steatosis, inflammation, fibrosis, tumorigenesis and regeneration is discussed in this review.

Receptor for advanced glycation endproducts (RAGE) is a key regulator of oval cell activation and inflammation-associated liver carcinogenesis in mice

The receptor for advanced glycation endproducts (RAGE) is a multiligand receptor and member of the immunoglobulin superfamily. RAGE is mainly involved in tissue damage and chronic inflammatory disorders, sustaining the inflammatory response upon engagement with damage-associated molecular pattern molecules (DAMPs) such as S100 proteins and high-mobility group box 1 (HMGB1). Enhanced expression of RAGE and its ligands has been demonstrated in distinct tumors and several studies support its crucial role in tumor progression and metastasis by still unknown mechanisms. Here we show that RAGE supports hepatocellular carcinoma (HCC) formation in the Mdr2(-/-) mouse model, a prototype model of inflammation-driven HCC formation, which mimics the human pathology. Mdr2(-/-) Rage(-/-) (dKO) mice developed smaller and fewer HCCs than Mdr2(-/-) mice. Interestingly, although in preneoplastic Mdr2(-/-) livers RAGE ablation did not affect the onset of inflammation, premalignant dKO livers showed reduced liver damage and fibrosis, in association with decreased oval cell activation. Oval cells expressed high RAGE levels and displayed reduced proliferation upon RAGE silencing. Moreover, stimulation of oval cells with HMGB1 promoted an ERK1/2-Cyclin D1-dependent oval cell proliferation in vitro. Finally, genetic and pharmacologic blockade of RAGE signaling impaired oval cell activation in an independent mouse model of oval cell activation, the choline deficient ethionine-supplemented dietary regime.

CONCLUSION

Our data identified a novel function of RAGE in regulating oval cell activation and tumor development in inflammation-associated liver carcinogenesis.

Expression of the Inflammatory Molecule HMGB1 in Human Osteosarcoma and its Clinical Relevance

High mobility group box 1 (HMGB1), known as a pro-inflammatory cytokine and chromatin-binding molecule, plays an important role in the carcinogenesis and metastasis of various tumors. The present study aimed to investigate the expression of HMGB1 in human osteosarcoma and its clinical relevance. At first, human osteosarcom tissues and their corresponding adjacent non-cancerous tissues (ANCT) from forty consecutive cases were collected. The expression of HMGB1 was detected by immunohistochemical assay through tissue microarray procedure and the correlation of HMGB1 expression with clinicopathologic factors was evaluated. Secondly, through small hairpin RNA(shRNA)-mediated HMGB1 knockdown in MG-63 osteosarcoma cells, we observed the changes of the biological behaviors of the osteosarcoma cells. As a consequence, the rate of positive expression of HMGB1 was significantly higher in osteosarcoma tissues than in the ANCT (60% vs 15%, P < 0.01). HMGB1 expression had significant positive correlation with Ennecking staging ( P = 0.034) and distant metastases ( P = 0.003), but had no correlation with the factors including age and gender of the patients, or histology and location of the tumor (each P > 0.05). Knockdown of HMGB1 down-regulated the expression of p-AKT, p-PI3K, PCNA, MMP-9 and CyclinD1, while it up-regulated the expression of cleaved caspase-3. More importantly, HMGB1 knockdown inhibited the proliferative activities and invasive potential, and induced apoptosis and cycle arrest in MG63 osteosarcoma cells. Taken together, our results indicate that HMGB1 was highly expressed in human osteosarcoma tissues, and the patients with higher HMGB1 expression in osteosarcoma tissues were more likely to have progression and metastasis of the disease. Knockdown of HMGB1 could inhibit the proliferation and invasion of osteosarcoma cells and induce its apoptosis through down-regulation of PI3K/AKT signaling pathway. HMGB1 could be a potential therapeutic target for osteosarcoma.

Overexpression of high mobility group box 1 and 2 is associated with the progression and angiogenesis of human bladder carcinoma

High mobility group box 1 (HMGB1) and HMGB2 overexpression has been observed in several human tumor types, and is involved in cancer progression and prognosis. However, the clinicopathological significance of HMGB1 and HMGB2 expression in bladder carcinoma (BCa), particularly the involvement of these proteins in angiogenesis, remains unclear. In the present study, immunohistochemistry and real-time polymerase chain reaction (PCR) of HMGB1 and HMGB2 in 64 BCa patients revealed that HMGB1 and HMGB2 were overexpressed in BCa tissues compared with normal tissues, and were correlated with tumor clinical stage and pathological grade. In addition, correlation analysis of vascular endothelial growth factor (VEGF) and microvessel density (MVD) counts indicated that the overexpression of HMGB1 and HMGB2 was also correlated with angiogenesis. We conclude that HMGB proteins act as key regulators in the progression and angiogenesis of bladder carcinoma, and serve as potential diagnostic and therapeutic targets.

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.

Predictive value of immunogenic cell death biomarkers HMGB1, sRAGE, and DNase in liver cancer patients receiving transarterial chemoembolization therapy

Transarterial chemoembolization (TACE) therapy is an effective locoregional anticancer treatment for liver cancer patients. Serum biomarkers involved in immunogenic cell death may be valuable for early predicting therapy response and estimating prognosis. Sera of 50 prospectively and consecutively included hepatocellular carcinoma (HCC) patients, undergoing TACE therapy, were taken before and 24 h after TACE application. In these samples, soluble biomarkers involved in immunogenic cell death, and among them, high-mobility group box 1 (HMGB1), soluble receptor of advanced glycation end products (sRAGE), and DNase activity were measured. They were compared with radiological response to therapy. A total of 71 TACE therapies were evaluated, of which 32 were classified as "no progression," and 39, as "progression." While HMGB1 levels increased already 24 h after TACE, there was an early decrease of sRAGE and DNase activity. Pretherapeutic and 24-h values of sRAGE were significantly higher in the no progression group than those in the progression group. There was no difference with respect to treatment response for DNase and HMGB1. Soluble RAGE is a new parameter with predictive relevance in primary liver cancer patients undergoing TACE therapy.

IL-33 and HMGB1 alarmins: sensors of cellular death and their involvement in liver pathology

'Alarmins' are a group of proteins or molecules that are released from cells during cellular demise to alert the host immune system. Two of them, Interleukin-33 (IL-33) and high-mobility group box-1 (HMGB1), share many similarities of cellular localization, functions and involvement in various inflammatory pathologies including hepatitis. The expressions of IL-33 and HMGB1, and their receptors ST2 and receptor for advanced glycation end products (RAGE), are substantially up-regulated during acute and chronic hepatitis. Recent data evidence a possible protective role of IL-33/ST2 axis during liver injury. A contrast in expression of IL-33 and HMGB1 alarmins were associated with type of hepatocellular death mediated by immune cells or hepato-toxic agents. The massive release of active form of IL-33 from hepatocytes may affect the recruitment and activation of its ST2-positive target immune cells in the liver to confer its alarmin functions. This review highlights the emerging roles of alarmin proteins in various liver pathologies, by focusing on classical HMGB1 and a newly discovered alarmin, the IL-33.

High-mobility group boxes mediate cell proliferation and radiosensitivity via retinoblastoma-interaction-dependent and -independent mechanisms

Our previous studies have shown that high-mobility group box 1 (HMGB1) could physically associate with the retinoblastoma (RB) protein via an LXCXE (leucine-X-cysteine-X-glutamic; X=any amino acid) motif. An identical LXCXE motif is present in the HMGB1-3 protein sequences, whereas a near-consensus LXCXD (leucine-X-cysteine-X-asparagine; X=any amino acid) motif is found in the HMGB4 protein. In this study, we have demonstrated that like HMGB1, HMGB2-3 also associated with the RB in vitro and in vivo, as evidenced by glutathione-s-transferase capture and immunoprecipitation-Western blot assays. A point mutation of the LXCXE or LXCXD motif led to disruption of RB:HMGB1-4 interactions. Enforced expression of HMGB1-3 or HMGB4 by adenoviral-vector-mediated gene transfer resulted in significant inhibition of breast cancer cell proliferation through an LXCXE- or LXCXD-dependent mechanism and an increased radiosensitivity through an LXCXE- or LXCXD-independent mechanism. These results suggest an important role of the LXCXE/D motif in RB:HMGB1-4 association and modulation of cancer cell growth, but not radiosensitivity.

Increased expression of HMGB1 is associated with poor prognosis in human bladder cancer

BACKGROUND AND OBJECTIVE

High-mobility group box 1 (HMGB1) is a versatile protein with intranuclear and extracellular functions that is involved in numerous biological and pathological processes, such as transcription, DNA repair, and response to infection and inflammation. HMGB1 overexpression has been reported in a variety of human cancers. However, the clinical significance of HMGB1 expression in bladder cancer (BC) remains unclear. This study is aimed to investigate the correlations between HMGB1 expression and prognosis in patients with BC.

METHODS

HMGB1 protein expression in 164 primary BC tissue specimens was analyzed by immunohistochemistry, and its association with clinicopathologic factors and prognosis was also analyzed.

RESULTS

HMGB1 protein had high expression in 87 of 164 cases of BC (53%). HMGB1 overexpression was significantly associated with tumor grade (P < 0.001), and stage (P = 0.001). The Kaplan-Meier survival analysis demonstrated that HMGB1 expression was significantly associated with shorter disease-free survival and overall survival (both P < 0.001). Multivariate analysis further demonstrated that HMGB1 was an independent prognostic factor for patients with BC.

CONCLUSIONS

HMGB1 might be a new molecular marker to predict the prognosis of patients with BC.

Reduced high-mobility group box 1 expression induced by RNA interference inhibits the bioactivity of hepatocellular carcinoma cell line HCCLM3

BACKGROUND

Increased expression of high-mobility group box 1 (HMGB1) has been observed in many tumor types, but the role of HMGB1 in hepatocellular carcinoma (HCC) is unknown.

AIMS

To examine the effects of RNA interference HMGB1 on the bioactivity of HCC cell line HCCLM3.

METHODS

We synthesized three specific small interfering RNAs of HMGB1 (HMGB1-siRNAs) and transfected these into HCCLM3 cells by use of Lipofectamine 2000. RT-PCR and Western blot were performed to determine the effects of HMGB1-siRNAs on HMGB1 expression and to detect NF-κB/p65 and VEGF-C expression after transfection of HMGB1-siRNAs into HCCLM3. In vitro proliferation was assessed by MTT assay. Migration and invasive ability were determined by use of the Transwell assay. Apoptosis was demonstrated by flow cytometry.

RESULTS

RT-PCR and Western blotting showed that all three specific HMGB1-siRNAs significantly inhibited HMGB1 expression, with inhibition by HMGB1-siRNA-1 being highest (70-80%). MTT assay demonstrated that the growth of cells transfected with HMGB1-siRNA-1 was significantly lower than that of control cells (P < 0.01). The Transwell assay showed that cell migration and invasion were significantly inhibited in HMGB1 knockdown cells compared with control cells (P < 0.01). FCM revealed that apoptosis was significantly increased in HMGB1-siRNA-1-transfected cells compared with control cells (P < 0.01). Expression of NF-κB/p65 and VEGF-C was inhibited in HCCLM3 cells transfected with HMGB1-siRNA-1 compared with control cells (P < 0.01).

CONCLUSION

Downregulation of HMGB1 could obviously inhibit the growth of HCCLM3 cells, and their migration and invasion ability. HMGB1 may serve as a potential target for treatment of HCC.

RAGE gene deletion inhibits the development and progression of ductal neoplasia and prolongs survival in a murine model of pancreatic cancer

BACKGROUND

The receptor for advanced glycation end-products (RAGE) is implicated in pancreatic tumorigenesis. Activating Kras mutations and p16 inactivation are genetic abnormalities most commonly detected as pancreatic ductal epithelium progresses from intraepithelial neoplasia (PanIN) to adenocarcinoma (PDAC).

OBJECTIVE

The aim of this study was to evaluate the effect of RAGE (or AGER) deletion on the development of PanIN and PDAC in conditional Kras ( G12D ) mice.

MATERIALS AND METHODS

Pdx1-Cre; LSL-Kras ( G12D/+) mice were crossed with RAGE (-/-) mice to generate Pdx1-Cre; LSL-Kras ( G12D/+) ; RAGE (-/-) mice. Pdx1-Cre; LSL-Kras ( G12D/+); p16 ( Ink4a-/-) mice were crossed with RAGE (-/-) mice to generate Pdx1-Cre; LSL-Kras ( G12D/+); p16 ( Ink4a-/-); RAGE (-/-) mice. Pancreatic ducts were scored and compared to the relevant RAGE (+/+) controls.

RESULTS

At 16 weeks of age, Pdx1-Cre; LSL-Kras ( G12D/+); RAGE (-/-) mice had significantly fewer high-grade PanIN lesions than Pdx1-Cre; LSL-Kras ( G12D/+); RAGE (+/+) controls. At 12 weeks of age, none of the Pdx1-Cre; LSL-Kras ( G12D/+); p16 ( Ink4a-/-); RAGE (-/-) mice had PDAC compared to a 45.5% incidence of PDAC in Pdx1-Cre; LSL-Kras ( G12D/+); p16 ( Ink4a-/-); RAGE (+/+) controls. Finally, Pdx1-Cre; LSL-Kras ( G12D/+); p16 ( Ink4a-/-); RAGE (-/-) mice also displayed markedly longer median survival.

CONCLUSION

Loss of RAGE function inhibited the development of PanIN and progression to PDAC and significantly prolonged survival in these mouse models. Further work is needed to target the ligand-RAGE axis for possible early intervention and prophylaxis in patients at risk for developing pancreatic cancer.

Therapeutic Effects of Ethyl Pyruvate on Tumor Growth and Metastasis in a Severe Combined Immunodeficiency Mouse Orthotopic Implantation Model

Ethyl pyruvate (EP) has been shown to have significant anti-inflammatory activities. Here, we explore the therapeutic effects of EP administration on tumor growth and metastasis in orthotopic implantation human gastric cancer models in severe combined immunodeficiency (SCID) mice. After SCID mice were treated with EP, the tumor growth and liver metastasis from gastric cancer were investigated and its possible molecular mechanisms were further studied. As a result, it was found that EP could inhibit tumor growth and liver metastasis of gastric cancer, and reduce tumor lymphangiogenesis indicated by lymphatic microvessel density (LVD) in gastric cancer and metastatic liver tumor. Also, EP decreased the expression of high mobility group box-B1 (HMGB1), receptor for advanced glycation endproducts (RAGE), vascular endothelial growth factor (VEGF) and membrane type-1 matrix metalloprotease (MT1-MMP) in gastric cancer and metastatic liver tumor, but it exerted no effect on expression of nuclear factor-kappa B (NF-κB). Taken together, we suggest that the new application of EP could be a therapeutic option in the treatment of gastric cancer and metastatic liver tumor.

High mobility group B1 protein interacts with its receptor RAGE in tumor cells but not in normal tissues

The high mobility group box 1 (HMGB1) protein is an abundant non-histone component of chromatin well known for its two DNA binding domains, HMG box A and HMG box B. The main characteristics of the HMGB1 protein as an 'architectural' factor are its ability to recognize and bind with high affinity to distorted DNA and its ability to induce kinks in linear DNA fragments. The HMGB1 protein has been correlated to cancer progression. An elevated expression of HMGB1 occurred in certain types of primary tumor, including melanoma and colon, prostate, pancreatic and breast cancers, and in the majority of cases HMGB1 is associated with invasion and metastasis. The main signaling pathway is activated through the interaction of HMGB1 with its Receptor for Advanced Glycation End products (RAGE). Certain data indicate that an elevated expression of RAGE and HMGB1 is not always a prerequisite of poor prognosis of tumor development. The cellular localization of the ligand/receptor pair also requires consideration. The data concerning the expression of HMGB1 protein and its receptor RAGE in various tissues and tumor cells reflect the overall production of the proteins. However, they do not refer to their cellular localization and there is no direct evidence for the formation of a stable complex between them. In the present study, we investigated the subcellular distribution of HMGB1 and its receptor RAGE in various rat organs compared to Guerin ascites tumor cells. In the normal tissues the proteins exist in their soluble form, whereas in the tumor cells they are insoluble and membrane-bound. HMGB1 forms a stable complex with RAGE only in the protein extract derived from the cancer cells predominantly in the membrane fraction.

High-mobility group box 1 is associated with clinicopathologic features in patients with hepatocellular carcinoma

High-mobility group box 1(HMGB1) has been associated with many human cancers, but the role of HMGB1 in hepatocellular carcinoma (HCC) remains unclear. The aim of this study is to investigate the expression of HMGB1 in human HCC with regard to its clinical significance. Twelve cases of normal liver tissues, 34 cases of HCC and the corresponding liver tissue just around the tumor (LAT) were collected. Then, all the samples were subjected to clinicopathologic examination, reverse transcription-polymerase chain reaction (RT-PCR), Western-blot (WB) and immunohistochemical analysis for the expression of HMGB1. The relationships between HMGB1 mRNA expression and clinicopathologic parameters were analyzed. RT-PCR demonstrated that the expression of relative HMGB1 mRNA (HMGB1/GAPDH) was 0.854 ± 0.172; the highest in the tissue of HCC, significantly up-regulated compared with that of 0.527 ± 0.155 in LAT and of 0.405 ± 0.087 in normal liver tissues (P < 0.001). HMGB1 mRNA overexpression was significantly associated with Edmondson stage, TNM stage, vascular invasion and capsule invasion. Western-blot showed the expression of HMGB1 protein in HCC also as the highest among all the groups. Furthermore this overexpression revealed by immunostaining was predominantly localized in the nuclei of HCC; whereas, none of the stains were seen in normal liver cells and only a trace of it was detected in the cytoplasm of LAT cells. Our results suggested the overexpression of HMGB1 might be an important pathogenetic factor in HCC. The mechanisms of HMGB1 in HCC genesis, development and its possible diagnostic and prognostic roles need to be further explored.

Pro-inflammatory gene expression in solid glioblastoma microenvironment and in hypoxic stem cells from human glioblastoma

Background

Adaptation to hypoxia and consequent pro-inflammatory gene expression of prostate and breast carcinomas have been implicated in the progression toward cancer malignant phenotype. Only partial data are available for the human tumor glioblastoma multiforme (GBM). The aim of our study was to analyze the hypoxic and pro-inflammatory microenvironment in GBMs and to demonstrate that in a stem/progenitor cell line derived from human glioblastoma (GBM-SCs), hypoxia activates a coordinated inflammatory response, evidencing an invasive and migratory phenotype.

Methods

From each of 10 human solid glioblastomas, clinically and histopathologically characterized, we obtained three surgical samples taken from the center and the periphery of the tumor, and from adjacent host normal tissue. Molecular and morphological analyses were carried out using quantitative real-time PCR and western blot (WB). GBM stem and differentiated cells were incubated under hypoxic conditions and analyzed for pro-inflammatory gene expression and for invasive/migratory behavior.

Results

A panel of selected representative pro-inflammatory genes (RAGE and P2X7R, COX2, NOS2 and, PTX3) were analyzed, comparing tumor, peritumor and host normal tissues. Tumors containing leukocyte infiltrates (as assessed using CD45 immunohistochemistry) were excluded. Selected genes were overexpressed in the central regions of the tumors (i.e. in the more hypoxic areas), less expressed in peripheral regions, and poorly expressed or absent in adjacent normal host tissues. Western blot analysis confirmed that the corresponding pro-inflammatory proteins were also differently expressed. Hypoxic stem cell lines showed a clear time-dependent activation of the entire panel of pro-inflammatory genes as compared to differentiated tumor cells. Biological assays showed that invasive and migratory behavior was strengthened by hypoxia only in GBM stem cells.

Conclusions

In human solid glioblastoma we have observed a coordinated overexpression of a panel of pro-inflammatory genes as compared to host normal tissue. We have also evidenced a similar pattern of overexpressed genes in GBM-SCs after hypoxic treatment, showing also a gain of invasive and migratory function that was lost when these stem cells differentiated. We suggest that, as has been previously described for prostatic and mammary carcinoma, in human glioblastoma acquisition of a proinflammatory phenotype may be relevant for malignant progression.

RAGE signaling significantly impacts tumorigenesis and hepatic tumor growth in murine models of colorectal carcinoma

BACKGROUND

The receptor for advanced glycation end-products (RAGE) is a cell surface receptor implicated in tumor cell proliferation and migration. We hypothesized that RAGE signaling impacts tumorigenesis and metastatic tumor growth in murine models of colorectal carcinoma.

MATERIALS AND METHODS

Tumorigenesis: Apc (1638N/+) mice were crossed with Rage (-/-) mice in the C57BL/6 background to generate Apc (1638N/+)/Rage (-/-) mice. Metastasis: BALB/c mice underwent portal vein injection with CT26 cells (syngeneic) and received daily soluble (s)RAGE or vehicle. Rage (-/-) mice and Rage (+/+) controls underwent portal vein injection with MC38 cells (syngeneic). Rage (+/+) mice underwent portal vein injection with MC38 cells after stable transfection with full-length RAGE or mock transfection control.

RESULTS

Tumorigenesis: Apc (1638N/+)/Rage (-/-) mice had reduced tumor incidence, size, and histopathologic grade. Metastasis: Pharmacological blockade of RAGE with sRAGE or genetic deletion of Rage reduced hepatic tumor incidence, nodules, and burden. Gain of function by transfection with full-length RAGE increased hepatic tumor burden compared to vector control MC38 cells.

CONCLUSION

RAGE signaling plays an important role in tumorigenesis and hepatic tumor growth in murine models of colorectal carcinoma. Further work is needed to target the ligand-RAGE axis for possible prophylaxis and treatment of primary and metastatic colorectal carcinoma.

Overexpression of high-mobility group box 2 is associated with tumor aggressiveness and prognosis of hepatocellular carcinoma

PURPOSE

We investigated the expression of high-mobility group box 2 (HMGB2) in patients with hepatocellular carcinoma (HCC) and its clinical effects with underlying mechanisms.

EXPERIMENTAL DESIGN

HMGB2 mRNA levels were measured in 334 HCC patients by real-time reverse transcription-PCR and HMGB2 protein levels in 173 HCC patients by immunohistochemical studies. The HMGB2 expression level was measured by Western blotting for three HCC cell lines. To clarify the precise role of HMGB2 on cell proliferation, we did in vitro analysis with expression vectors and small interfering RNAs.

RESULTS

HMGB2 mRNA and protein expression were significantly higher in HCC than in noncancerous surrounding tissues (P < 0.0001) and showed a positive correlation (ρ = 0.35, P < 0.001). HMGB2 overexpression was significantly correlated with shorter overall survival time, both at mRNA (P = 0.0054) and protein level (P = 0.023). Moreover, HMGB2 mRNA level was an independent prognostic factor for overall survival in a multivariate analysis (P = 0.0037). HMGB2 knockdown by small interfering RNAs decreased cell proliferation, and overexpression of HMGB2 by expression vectors diminished cisplatin- and etoposide-induced cell death.

CONCLUSIONS

Our clinical and in vitro data suggest that HMGB2 plays a significant role in tumor development and prognosis of HCC. These results can partly be explained by altered cell proliferations by HMGB2 associated with the antiapoptotic pathway.