High mobility group box 1 antagonist limits metastatic seeding in the lungs via reduction of cell-cell adhesion

HMGB1 in the interplay between autophagy and apoptosis in cancer

Lysosome-mediated autophagy and caspase-dependent apoptosis are dynamic processes that maintain cellular homeostasis, ensuring cell health and functionality. The intricate interplay and reciprocal regulation between autophagy and apoptosis are implicated in various human diseases, including cancer. High-mobility group box 1 (HMGB1), a nonhistone chromosomal protein, plays a pivotal role in coordinating autophagy and apoptosis levels during tumor initiation, progression, and therapy. The regulation of autophagy machinery and the apoptosis pathway by HMGB1 is influenced by various factors, including the protein's subcellular localization, oxidative state, and interactions with binding partners. In this narrative review, we provide a comprehensive overview of the structure and function of HMGB1, with a specific focus on the interplay between autophagic degradation and apoptotic death in tumorigenesis and cancer therapy. Gaining a comprehensive understanding of the significance of HMGB1 as a biomarker and its potential as a therapeutic target in tumor diseases is crucial for advancing our knowledge of cell survival and cell death.

Co-expression of High-mobility group box 1 protein (HMGB1) and receptor for advanced glycation end products (RAGE) in the prognosis of esophageal squamous cell carcinoma

Esophageal cancer is a malignant type of cancer with a high mortality rate. The aim of this study is to determine co-expression patterns of High-mobility group box 1 protein (HMGB1) and receptor for advanced glycation end products (RAGE) in ESCC (esophageal squamous cell carcinoma) conditions and their prognostic role in cancer progression. The expression of HMGB1 and RAGE in ESCC tissues has been analyzed using qRT-PCR and Western blotting. Co-localized expression patterns of HMGB1 and RAGE in ESCC tissues were determined using immunohistochemistry and analyzed for clinical-pathological parameters. Overall survival was performed based on co-expression of HMGB1 and RAGE proteins. A higher expression pattern of HMGB1, and RAGE was observed at mRNA and protein level in the ESCC group compared to the adjacent tissue group. Expression of HMGB1 was significantly correlated with lymph node, metastasis, lymphatic invasion, and venous invasion (p < 0.05). RAGE expression exhibited a significant correlation with venous invasion. Overall survival was significantly shorter (P < 0.05) in the patients with co-expression of HMGB1 and RAGE compared to the patients without co-expression. A significant difference in the overall survival was evident between the patients with co-expression of HMGB1 and RAGE and the patients without coexpression. HMGB1 and RAGE expression patterns were associated with aggressive metastatic characteristics of ESCC. The co-expression of HMGB1 and RAGE was correlated with shorter survival times. Results concluded the co-expression patterns of HMGB1 and RAGE exhibited a prognostic relevance in ESCC conditions.

HΜGB1/sRAGE levels differ significantly between transudates and exudates

High mobility group box 1(HMGB1) protein operates as an alarmin with multiple roles in immunity and cell homeostasis. It is highly expressed in epithelial barrier sites and acts via the binding to the receptor for advanced glycation end products (RAGE). Production of HMGB1 and soluble RAGE (sRAGE), a decoy receptor for HMGB1, has been implicated in several pulmonary diseases, but both have been scarcely investigated in pleural diseases. The aim of this study was to determine the levels of HMGB1 and sRAGE in transudative, malignant and parapneumonic pleural effusions (PEs) and to investigate the effect of low and high HMGB1 pleural fluid levels on MeT-5A cell adhesion, migration and spheroid formation, in each group. HMGB1 and sRAGE levels were significantly lower and higher in transudative PEs compared to malignant and parapneumonic PEs, respectively. Patients above 65 years of age had significantly lower HMGB1 and higher sRAGE levels compared to patients below 65 years old. Furthermore, incubation of MeT-5A cells with malignant or parapneumonic PEs bearing low or high levels of HMGB1 yielded significant differential effects on MeT-5A cell adhesion, migration and spheroid formation. In all types of effusions, high HMGB1 levels correlated with more adherence compared to low HMGB1 levels. In transudative and malignant PEs high HMGB1 levels correlated with decreased migration of MeT-5A cells while in parapneumonic ones the effect was the opposite. Only samples from parapneumonic PEs high in HMGB1 achieved uniform spheroid formation. These results reveal a clinical context-dependent effect of the HMGB1/sRAGE axis in PEs.

Recombinant human soluble thrombomodulin attenuates anti-glomerular basement membrane glomerulonephritis in Wistar-Kyoto rats through anti-inflammatory effects

BACKGROUND

Since recombinant human soluble thrombomodulin (RH-TM) has anti-inflammatory properties through neutralizing high-mobility group box 1 protein (HMGB1), the protective effects of RH-TM were examined in anti-glomerular basement membrane (GBM) glomerulonephritis (GN) in Wistar-Kyoto rats.

METHODS

Rats were injected with nephrotoxic serum (NTS) to induce anti-GBM GN on Day 0, and were given either RH-TM or vehicle from Day 0 to Day 6. Rats were sacrificed 7 days after NTS injection.

RESULTS

RH-TM-treated rats had decreased proteinuria and serum creatinine level. RH-TM significantly reduced the percentage of glomeruli with crescentic features and fibrinoid necrosis. In addition, RH-TM-treated rats had significantly reduced glomerular ED1+ macrophage accumulation as well as reduced renal cortical proinflammatory cytokine expression. Furthermore, RH-TM had a potent effect in reducing intercellular adhesion molecule-1 (ICAM-1) expression in kidneys and urine. RH-TM significantly reduced renal cortical mRNA levels for toll-like receptor -2 and -4, known as receptors for HMGB1, and their downstream adopter protein, myeloid differentiation primary respond protein 88 (MyD88).

CONCLUSIONS

We showed for the first time that anti-inflammatory effects, which were characterized by reduced glomerular macrophage influx concomitant with a marked reduction in proinflammatory cytokines, were involved in the mechanism of attenuating experimental anti-GBM GN by RH-TM. The observed effects might be attributable to the downregulation of ICAM-1 by reducing the HMGB1/TLR/MyD88 signaling pathway.

Necrosis in the Tumor Microenvironment and Its Role in Cancer Recurrence

Cancer recurrence is one of the most imminent problems in the current world of medicine, and it is responsible for most of the cancer-related death rates worldwide. Long-term administration of anticancer cytotoxic drugs may act as a double-edged sword, as necrosis may lead to renewed cancer progression and treatment resistance. The lack of nutrients, coupled with the induced hypoxia, triggers cell death and secretion of signals that affect the tumor niche. Many efforts have been made to better understand the contribution of hypoxia and metabolic stress to cancer progression and resistance, but mostly with respect to inflammation. Here we provide an overview of the direct anticancer effects of necrotic signals, which are not necessarily mediated by inflammation and the role of DAMPs (damage-associated molecular patterns) on the formation of a pro-cancerous environment.

Encapsulated Carbenoxolone Reduces Lung Metastases

Carbenoxolone is an anti-inflammatory compound and a derivate of a natural substance from the licorice plant. We previously showed that carbenoxolone reduces the metastatic burden in the lungs of mice through its antagonistic effect on high mobility group box 1 (HMGB1). To further enhance carbenoxolone's activity and localization in the lungs, thereby reducing the potential adverse side effects resulting from systemic exposure, we developed a poly(lactic-co-glycolic acid) (PLGA) slow-release system for pulmonary delivery which maintains drug activity in-vitro, as demonstrated in the anoikis assay. Both systemic and intranasal administrations of carbenoxolone effectively minimize metastatic formation in a lung colonization model in mice. Our results show a decrease in the metastatic burden in the lung tissue. Notably, the therapeutic effect of a single intranasal administration of 25 mg/kg carbenoxolone, in the form of drug-loaded particles, had a similar effect in reducing metastatic lesions in the lungs to that of a 10-fold dose of the free drug via intraperitoneal injections, three times per week over the course of four weeks. These data offer new means to potentiate the anti-cancer activity of carbenoxolone and simultaneously reduce the requirement for high dosage administration; the upshot substantially improves therapeutic effect and avoidance of side effects.

Tissue necrosis and its role in cancer progression

Great efforts have been made in revealing the mechanisms governing cancer resistance and recurrence. The in-situ effects of cell death, caused by hypoxia and metabolic stress, were largely studied in association with inflammation. However, in this work, we focused on the direct effects of necrosis on cancer promotion and on the tumor microenvironment. The conditions leading to cell necrosis, upon nutrient and oxygen deprivation, were recapitulated in-vitro and were used to generate samples for computational proteomic analysis. Under these conditions, we identified clusters of enriched pathways that may be involved in tumor resistance, leading to cancer recurrence. We show that the content of necrotic cells enhances angiogenesis and proliferation of endothelial cells, induces vasculature, as well as increases migration, invasion, and cell-cell interactions. In-vivo studies, where MDA-MB-231 xenografts were exposed to necrotic lysates, resulted in an increase in both proliferation and angiogenesis. Histological analysis of tumor tissues revealed high expression levels of key mediators that were identified by proteomic analysis. Moreover, when cells were injected systemically, coupled with necrotic lysates, a higher number of large lesions was detected in the lung. Finally, using xenografts, we demonstrated that combining an antagonist of a necrotic signal with an anticancer treatment potentiates the prolonged therapeutic effect. This approach suggests a paradigm shift in which targeting late necrotic-secreted factors may increase survival and enhance the efficacy of anticancer therapy.

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

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

RAGE-specific single chain Fv for PET imaging of pancreatic cancer

Noninvasive detection of both early pancreatic neoplasia and metastases could enhance strategies to improve patient survival in this disease that is notorious for an extremely poor prognosis. There are almost no identifiable targets for non-invasive diagnosis by positron emission tomography (PET) for patients with pancreatic ductal adenocarcinoma (PDAC). Over-expression of the receptor for advanced glycation end products (RAGE) is found on the cell surface of both pre-neoplastic lesions and invasive PDAC. Here, a RAGE-specific single chain (scFv) was developed, specific for PET imaging in syngeneic mouse models of PDAC. An anti-RAGE scFv conjugated with a sulfo-Cy5 fluorescence molecule showed high affinity and selectivity for RAGE expressing pancreatic tumor cells and genetically engineered KRAS^G12D mouse models of PDAC. An in vivo biodistribution study was performed with the ⁶⁴Cu-radiolabled scFv in a syngeneic murine pancreatic cancer model, demonstrating both the feasibility and potential of an anti-RAGE scFv for detection of PDAC. These studies hold great promise for translation into the clinic.