HMGB1 in Radiotherapy: A Two Headed Signal Regulating Tumor Radiosensitivity and Immunity

RAGE as a Novel Biomarker for Prostate Cancer: A Systematic Review and Meta-Analysis

The receptor for advanced glycation end-products (RAGE) has been implicated in driving prostate cancer (PCa) growth, aggression, and metastasis through the fueling of chronic inflammation in the tumor microenvironment. This systematic review and meta-analysis summarizes and analyzes the current clinical and preclinical data to provide insight into the relationships among RAGE levels and PCa, cancer grade, and molecular effects. A multi-database search was used to identify original clinical and preclinical research articles examining RAGE expression in PCa. After screening and review, nine clinical and six preclinical articles were included. The associations of RAGE differentiating benign prostate hyperplasia (BPH) or normal prostate from PCa and between tumor grades were estimated using odds ratios (ORs) and associated 95% confidence intervals (CI). Pooled estimates were calculated using random-effect models due to study heterogeneity. The clinical meta-analysis found that RAGE expression was highly likely to be increased in PCa when compared to BPH or normal prostate (OR: 11.3; 95% CI: 4.4-29.1) and that RAGE was overexpressed in high-grade PCa when compared to low-grade PCa (OR: 2.5; 95% CI: 1.8-3.4). In addition, meta-analysis estimates of preclinical studies performed by albatross plot generation found robustly positive associations among RAGE expression/activation and PCa growth and metastatic potential. This review demonstrates that RAGE expression is strongly tied to PCa progression and can serve as an effective diagnostic target to differentiate between healthy prostate, low-grade PCa, and high-grade PCa, with potential theragnostic applications.

The Redox Protein High-Mobility Group Box 1 in Cell Death and Cancer

Significance: As a redox-sensitive protein, high-mobility group box 1 (HMGB1) is implicated in regulating stress responses to oxidative damage and cell death, which are closely related to the pathology of inflammatory diseases, including cancer. Recent Advances: HMGB1 is a nonhistone nuclear protein that acts as a deoxyribonucleic acid chaperone to control chromosomal structure and function. HMGB1 can also be released into the extracellular space and function as a damage-associated molecular pattern protein during cell death, including during apoptosis, necrosis, necroptosis, pyroptosis, ferroptosis, alkaliptosis, and cuproptosis. Once released, HMGB1 binds to membrane receptors to shape immune and metabolic responses. In addition to subcellular localization, the function and activity of HMGB1 also depend on its redox state and protein posttranslational modifications. Abnormal HMGB1 plays a dual role in tumorigenesis and anticancer therapy (e.g., chemotherapy, radiation therapy, and immunotherapy) depending on the tumor types and stages. Critical Issues: A comprehensive understanding of the role of HMGB1 in cellular redox homeostasis is important for deciphering normal cellular functions and pathological manifestations. In this review, we discuss compartmental-defined roles of HMGB1 in regulating cell death and cancer. Understanding these advances may help us develop potential HMGB1-targeting drugs or approaches to treat oxidative stress-related diseases or pathological conditions. Future Directions: Further studies are required to dissect the mechanism by which HMGB1 maintains redox homeostasis under different stress conditions. A multidisciplinary effort is also required to evaluate the potential applications of precisely targeting the HMGB1 pathway in human health and disease. Antioxid. Redox Signal. 39, 569-590.

Potential of damage associated molecular patterns in synergising radiation and the immune response in oesophageal cancer

BACKGROUND

There is an intimate crosstalk between cancer formation, dissemination, treatment response and the host immune system, with inducing tumour cell death the ultimate therapeutic goal for most anti-cancer treatments. However, inducing a purposeful synergistic response between conventional therapies and the immune system remains evasive. The release of damage associated molecular patterns (DAMPs) is indicative of immunogenic cell death and propagation of established immune responses. However, there is a gap in the literature regarding the importance of DAMP expression in oesophageal adenocarcinoma (OAC) or by immune cells themselves.

AIM

To investigate the effects of conventional therapies on DAMP expression and to determine whether OAC is an immunogenic cancer.

METHODS

We investigated the levels of immunogenic cell death-associated DAMPs, calreticulin (CRT) and HMGB1 using an OAC isogenic model of radioresistance. DAMP expression was also assessed directly using ex vivo cancer patient T cells (n = 10) and within tumour biopsies (n = 9) both pre and post-treatment with clinically relevant chemo(radio)therapeutics.

RESULTS

Hypoxia in combination with nutrient deprivation significantly reduces DAMP expression by OAC cells in vitro. Significantly increased frequencies of T cell DAMP expression in OAC patients were observed following chemo(radio)therapy, which was significantly higher in tumour tissue compared with peripheral blood. Patients with high expression of HMGB1 had a significantly better tumour regression grade (TRG 1-2) compared to low expressors.

CONCLUSION

In conclusion, OAC expresses an immunogenic phenotype with two distinct subgroups of high and low DAMP expressors, which correlated with tumour regression grade and lymphatic invasion. It also identifies DAMPs namely CRT and HMGB1 as potential promising biomarkers in predicting good pathological responses to conventional chemo(radio)therapies currently used in the multimodal management of locally advanced disease.

Novel Drugs and Radiotherapy in Relapsed Lymphomas: Abscopal Response and Beyond

Combined modality has represented a mainstay of treatment across many lymphoma histologies, given their sensitivity to both multi-agent chemotherapy and intermediate-dose radiotherapy. More recently, several new agents, including immunotherapies, have reshaped the therapeutic panorama of some lymphomas. In parallel, radiotherapy techniques have witnessed substantial improvement, accompanied by a growing understanding that radiation itself comes with an immune-mediated effect. Six decades after a metastatic lesion regression outside the irradiated field was first described, there is increasing evidence that a combination of radiotherapy and immunotherapy could boost an abscopal effect. This review focuses on the mechanisms underlying this interaction in the setting of lymphomas, and on the results of pivotal prospective studies. Furthermore, the available evidence on the concomitant use of radiotherapy and small molecules (i.e., lenalidomide, venetoclax, and ibrutinib), as well as brentuximab vedotin, and chimeric antigen receptor (CAR) T-cell therapy, is summarized. Currently, combining radiotherapy with new agents in patients who are affected by lymphomas appears feasible, particularly as a bridge to anti-CD19 autologous CAR T-cell infusion. However, more studies are required to assess these combinations, and preliminary data suggest only a synergistic rather than a curative effect.

CAR T cell-based immunotherapy and radiation therapy: potential, promises and risks

CAR T cell-based therapies have revolutionized the treatment of hematological malignancies such as leukemia and lymphoma within the last years. In contrast to the success in hematological cancers, the treatment of solid tumors with CAR T cells is still a major challenge in the field and attempts to overcome these hurdles have not been successful yet. Radiation therapy is used for management of various malignancies for decades and its therapeutic role ranges from local therapy to a priming agent in cancer immunotherapy. Combinations of radiation with immune checkpoint inhibitors have already proven successful in clinical trials. Therefore, a combination of radiation therapy may have the potential to overcome the current limitations of CAR T cell therapy in solid tumor entities. So far, only limited research was conducted in the area of CAR T cells and radiation. In this review we will discuss the potential and risks of such a combination in the treatment of cancer patients.

Optimal timing and sequence of combining stereotactic radiosurgery with immune checkpoint inhibitors in treating brain metastases: clinical evidence and mechanistic basis

Recent evidence has shown that immune checkpoint inhibitors (ICIs) are efficacious for treating brain metastases of various primary tumors. However, the immunosuppressive tumor microenvironment and the blood-brain barrier (BBB) or blood-tumor barrier (BTB) essentially restrict the efficacy of ICIs. Stereotactic radiosurgery (SRS) can be a powerful ally to ICIs due to its trait of disrupting the BBB/BTB and increasing the immunogenicity of brain metastases. The combination of SRS + ICI has shown synergy in brain metastases in several retrospective studies. Nevertheless, the optimal schedule for the combination of SRS and ICI in brain metastases is yet to be determined. In this review, we summarized the current clinical and preclinical evidence on the timing and sequence of SRS + ICI to provide insight into the current state of knowledge about this important area in patient care.

Radiotherapy, PARP Inhibition, and Immune-Checkpoint Blockade: A Triad to Overcome the Double-Edged Effects of Each Single Player

Radiotherapy and, more recently, PARP inhibitors (PARPis) and immune-checkpoint inhibitors represent effective tools in cancer therapy. Radiotherapy exerts its effects not only by damaging DNA and inducing tumor cell death, but also stimulating anti-tumor immune responses. PARPis are known to exert their therapeutic effects by inhibiting DNA repair, and they may be used in combination with radiotherapy. Both radiotherapy and PARPis modulate inflammatory signals and stimulate type I IFN (IFN-I)-dependent immune activation. However, they can also support the development of an immunosuppressive tumor environment and upregulate PD-L1 expression on tumor cells. When provided as monotherapy, immune-checkpoint inhibitors (mainly antibodies to CTLA-4 and the PD-1/PD-L1 axis) result particularly effective only in immunogenic tumors. Combinations of immunotherapy with therapies that favor priming of the immune response to tumor-associated antigens are, therefore, suitable strategies. The widely explored association of radiotherapy and immunotherapy has confirmed this benefit for several cancers. Association with PARPis has also been investigated in clinical trials. Immunotherapy counteracts the immunosuppressive effects of radiotherapy and/or PARPis and synergies with their immunological effects, promoting and unleashing immune responses toward primary and metastatic lesions (abscopal effect). Here, we discuss the beneficial and counterproductive effects of each therapy and how they can synergize to overcome single-therapy limitations.

The redox protein HMGB1 in cell death and cancer

SIGNIFICANCE

As a redox-sensitive protein, high-mobility group box 1 (HMGB1) is implicated in regulating stress responses to oxidative damage and cell death, which are closely related to the pathology of inflammatory diseases, including cancer.

RECENT ADVANCES

HMGB1 is a non-histone nuclear protein that acts as a DNA chaperone to control chromosomal structure and function. HMGB1 can also be released into the extracellular space and function as a damage-associated molecular pattern protein during cell death, including during apoptosis, necrosis, necroptosis, pyroptosis, ferroptosis, alkaliptosis, and cuproptosis. Once released, HMGB1 binds to membrane receptors to shape immune and metabolic responses. In addition to subcellular localization, the function and activity of HMGB1 also depends on its redox state and protein posttranslational modifications. Abnormal HMGB1 plays a dual role in tumorigenesis and anticancer therapy (e.g., chemotherapy, radiation therapy, and immunotherapy) depending on tumor types and stages.

CRITICAL ISSUES

A comprehensive understanding of the role of HMGB1 in cellular redox homeostasis is important for deciphering normal cellular functions and pathological manifestations. In this review, we discuss compartmental-defined roles of HMGB1 in regulating cell death and cancer. Understanding these advances may help us develop potential HMGB1-targeting drugs or approaches to treat oxidative stress-related diseases or pathological conditions.

FUTURE DIRECTIONS

Further studies are required to dissect the mechanism by which HMGB1 maintains redox homeostasis under different stress conditions. A multidisciplinary effort is also required to evaluate the potential applications of precisely targeting the HMGB1 pathway in human health and disease.

Ionizing Radiation Triggers the Antitumor Immunity by Inducing Gasdermin E-Mediated Pyroptosis in Tumor Cells

PURPOSE

To understand pyroptosis induced by ionizing radiation and its implications for radiation therapy, we explored the involved factors, possible mechanisms of radiation-induced pyroptosis and consequent antitumor immunity.

METHODS AND MATERIALS

The occurrence of pyroptosis was assessed by cell morphology, lactate dehydrogenase release, Annexin V/PI staining and the cleavage of Gasdermin E (GSDME). Cell radiosensitivity was tested with MTT and colony survival assays. Xenograft tumor volume, Ki-67, CD8⁺ lymphocytes, and ELISA were used to evaluate the effect of GSDME on tumor suppression after irradiation.

RESULTS

Irradiation induced pyroptosis in GSDME high-expressing tumor cell lines covering lung, liver, breast, and glioma cancers. Cleavage of GSDME occurred in a dose- and time-dependent manner after irradiation, and pyroptosis could be induced by various kinds of irradiation. The combination of chemotherapy drugs for DNA damage (cisplatin or etoposide) or demethylation (decitabine or azacytidine) and irradiation significantly enhanced the occurrence of pyroptosis. Moreover, we revealed that the Caspase 9/Caspase 3/GSDME pathway was involved in irradiation-induced pyroptosis. Notably, enhanced tumor suppression was observed in Balb/c mice bearing GSDME-overexpressing 4T1 tumors compared with those bearing vector tumors for the promotion of antitumor immunity, which was manifested as distinctly elevated levels of cytotoxic T lymphocytes and release of the related cytokines rather than the direct effect of pyroptosis on tumor cell radiosensitivity.

CONCLUSIONS

As an immunogenic cell death caused by radiation, pyroptosis promotes antitumor immunity after irradiation. Our findings may provide new insights to improve the efficacy of tumor radiation therapy.

Effect of Proton Therapy on Tumor Cell Killing and Immune Microenvironment for Hepatocellular Carcinoma

Radiotherapy with proton therapy (PT) has dosimetric advantages over photon therapy, which helps to enlarge the therapeutic window of radiotherapy for hepatocellular carcinoma (HCC). We evaluated the response of HCC to PT and examined the underlying mechanisms. The human liver cancer cell lines HepG2 and HuH7 and the murine liver cancer cell line Hepa1-6 were selected for cell and animal experiments to examine the response induced by PT irradiation. Biological changes and the immunological response following PT irradiation were examined. In vitro experiments showed no significant difference in cell survival following PT compared with photon radiotherapy. In a murine tumor model, the tumors were obviously smaller in size 12 days after PT irradiation. The underlying changes included increased DNA damage, upregulated IL-6 levels, and a regulated immune tumor microenvironment. Protein analysis in vitro and in vivo showed that PT increased the level of programmed cell death ligand 1 (PD-L1) expressed in tumor cells and recruited myeloid-derived suppressor cells (MDSCs). The increase in PD-L1 was positively correlated with the irradiation dose. In Hepa1-6 syngeneic mouse models, the combination of PT with anti-PD-L1 increased tumor growth delay compared with PT alone, which was associated with increased tumor-infiltrating T cells and attenuated MDSC recruitment in the microenvironment. Furthermore, when PT was applied to the primary HCC tumor, anti-PD-L1 antibody-treated mice showed smaller synchronous unirradiated tumors. In conclusion, the response of HCC to PT was determined by tumor cell killing and the immunological response in the tumor microenvironment. The combination with the anti-PD-L1 antibody to enhance antitumor immunity was responsible for the therapeutic synergism for HCC treated with PT. Based on our results, we suggest that PT combined with anti-PD-L1 may be a promising therapeutic policy for HCC.

HMGB1 Positive Feedback Loop Between Cancer Cells and Tumor-Associated Macrophages Promotes Osteosarcoma Migration and Invasion

Numerous studies have demonstrated the key roles of tumor-associated macrophages (TAMs) in osteosarcoma metastasis. Higher levels of high mobility group box 1 (HMGB1) promote osteosarcoma progression. However, whether HMGB1 is involved in the polarization of M2 macrophages into M1 macrophages in osteosarcoma remains largely unknown. Here, HMGB1 and CD206 mRNA expression levels were measured by a quantitative reverse transcription-polymerase chain reaction in osteosarcoma tissues and cells. HMGB1 and receptor for advanced glycation end products (RAGE) protein expression levels were measured by western blotting. Osteosarcoma migration was measured using transwell and wound-healing assays, while a transwell assay determined osteosarcoma invasion. Macrophage subtypes were detected using flow cytometry. HMGB1 expression levels were aberrantly enhanced in osteosarcoma tissues compared with normal tissues and were positively correlated with AJCC III and IV stages, lymph node metastasis, and distant metastasis. Silencing HMGB1 inhibited the migration, invasion, and epithelial-mesenchymal transition (EMT) of osteosarcoma cells. Furthermore, reduced HMGB1 expression levels in conditioned media derived from osteosarcoma cells induced the polarization of M2 TAMs to M1 TAMs. In addition, silencing HMGB1 inhibited the liver and lung metastasis of tumors and reduced the expression levels of HMGB1, CD163, and CD206 in vivo. HMGB1 was found to regulate macrophage polarization through RAGE. Polarized M2 macrophages induced osteosarcoma migration and invasion, activating HMGB1 expression in osteosarcoma cells to form a positive feedback loop. In conclusion, HMGB1 and M2 macrophages enhanced osteosarcoma migration, invasion, and EMT through positive feedback regulation. These findings reveal the significance of tumor cell and TAM interactions in the metastatic microenvironment.

Irradiation immunity interactions

The immune system can influence cancer development by both impeding and/or facilitating tumour growth and spread. A better understanding of this complex relationship is fundamental to optimise current and future cancer therapeutic strategies. Although typically regarded as a localised and immunosuppressive anti‐cancer treatment modality, radiation therapy has been associated with generating profound systemic effects beyond the intended target volume. These systemic effects are immune‐driven suggesting radiation therapy can enhance anti‐tumour immunosurveillance in some instances. In this review, we summarise how radiation therapy can positively and negatively affect local and systemic anti‐tumour immune responses, how co‐administration of immunotherapy with radiation therapy may help promote anti‐tumour immunity, and how the use of immune biomarkers may help steer radiation therapy‐immunotherapy personalisation to optimise clinical outcomes.

Dynamics of HMBG1 (High Mobility Group Box 1) during radiochemotherapy correlate with outcome of HNSCC patients

Purpose

High Mobility Group Box 1 (HMGB1) protein has been described as a consensus marker for immunogenic cell death (ICD) in cancer. To personalize treatments, there is a need for biomarkers to adapt dose prescription, concomitant chemotherapy, and follow-up in radiation oncology. Thus, we investigated the levels of HMGB1 in plasma of patients with head and neck squamous cell carcinoma (HNSCC) during the course of radiochemotherapy and follow-up in correlation with oncologic outcome and clinical confounders.

Methods

In our pilot study, 11 patients with advanced HNSCC were treated with definitive radiochemotherapy. Blood samples were taken weekly during treatment and frequently at follow-up visits. HMGB1 levels as well as routine laboratory values were measured and clinical information was collected including tumor volume, infections, toxicity, and follow-up data.

Results

In total, 85 samples were analyzed. In eight patients, HMGB1 levels (baseline vs. last available sample during treatment) were increasing and in three patients HMGB1 values were decreasing toward the end of treatment. All three patients with decreasing values developed tumor recurrence. By contrast, no relapse occurred in patients that showed increasing HMGB1 levels during therapy. Moreover, a positive correlation of HMGB1 levels with tumor volumes, C‑reactive protein (CRP) levels, infections, and grade three toxicity (RTOG) was observed.

Conclusion

HMGB1 might be a promising marker to monitor ICD in HNSCC during the course of radiochemotherapy. However, HMGB1 seems to reflect complex and diverse immunogenic responses and potential confounders. Infections and treatment-associated toxicity should be considered when interpreting the dynamics of HMGB1.

Immunogenic Cell Death Induction by Ionizing Radiation

Immunogenic cell death (ICD) is a form of regulated cell death (RCD) induced by various stresses and produces antitumor immunity via damage-associated molecular patterns (DAMPs) release or exposure, mainly including high mobility group box 1 (HMGB1), calreticulin (CRT), adenosine triphosphate (ATP), and heat shock proteins (HSPs). Emerging evidence has suggested that ionizing radiation (IR) can induce ICD, and the dose, type, and fractionation of irradiation influence the induction of ICD. At present, IR-induced ICD is mainly verified in vitro in mice and there is few clinical evidence about it. To boost the induction of ICD by IR, some strategies have shown synergy with IR to enhance antitumor immune response, such as hyperthermia, nanoparticles, and chemotherapy. In this review, we focus on the molecular mechanisms of ICD, ICD-promoting factors associated with irradiation, the clinical evidence of ICD, and immunogenic forms of cell death. Finally, we summarize various methods of improving ICD induced by IR.

Restoring the Immunity in the Tumor Microenvironment: Insights into Immunogenic Cell Death in Onco-Therapies

Immunogenic cell death (ICD) elicited by cancer therapy reshapes the tumor immune microenvironment. A long-term adaptative immune response can be initiated by modulating cell death by therapeutic approaches. Here, the major hallmarks of ICD, endoplasmic reticulum (ER) stress, and damage-associated molecular patterns (DAMPs) are correlated with ICD inducers used in clinical practice to enhance antitumoral activity by suppressing tumor immune evasion. Approaches to monitoring the ICD triggered by antitumoral therapeutics in the tumor microenvironment (TME) and novel perspective in this immune system strategy are also reviewed to give an overview of the relevance of ICD in cancer treatment.

ALKBH5-Modified HMGB1-STING Activation Contributes to Radiation Induced Liver Disease via Innate Immune Response

PURPOSE

Radiation therapy, which is vital for the treatment of primary liver cancer, comes with unavoidable liver injury, which limits its implementation. N6-methyladenosine (m6A) methylation is involved in many molecular functions. However, its role in radiation-induced liver diseases (RILD) remains unknown. Herein, we investigate the role of m6A methylation in RILD.

METHODS AND MATERIALS

Methylated RNA-immunoprecipitation sequencing and RNA transcriptome sequencing were used to reveal the methylation pattern of human hepatic stellate cells (HSCs) exposed to irradiation. C3H/HeN mice and stimulator of interferon genes (STING)-deficient mice underwent x-ray irradiation of 24 Gy in 3 fractions. The m6A methylation of the high-mobility group box 1 (HMGB1) transcript was validated using methylated RNA immunoprecipitation, RNA immunoprecipitation, luciferase assays, and a messenger RNA decay assay.

RESULTS

Human hepatic stellate cells showed significant differences in methylation patterns after 8 Gy of x-ray irradiation. Irradiation recruited AlkB homolog 5 (ALKBH5) to demethylate m6A residues in the 3' untranslated region of HMGB1, which resulted in the activation of STING-interferon regulatory factor 3 signaling. Changes in the transcription of the 3' untranslated region of HMGB1 occurred after the knockdown of ALKBH5, which were eliminated after m6A residue mutation. Strikingly, ALKBH5 deficiency or HMGB1 silencing both attenuated type I interferon production and decreased hepatocyte apoptosis. In vivo depletion of ALKBH5 abolished the upregulation of HMGB1-mediated STING signaling and decreased liver inflammation, which was consistent with STING^-/- mice treated with irradiation. Notably, YTHDF2 (m6A reader protein) directly bound to HMGB1 m6A-modified sites and promoted its degradation.

CONCLUSIONS

ALKBH5-dependent HMGB1 expression mediates STING-interferon regulatory factor 3 innate immune response in RILD.

Rapid Arc-SBRT: Non-invasive immune adjuvant for advanced stage Non-Small Cell Lung Carcinoma

In conjunction with Radio-chemotherapy, pulmonary resection is recommended for early-stage Non-small-cell lung carcinoma but not for advanced-stage NSCLC patients with having high-grade metastatic lesions. In these cases, Rapid Arc-Stereotactic body radiotherapy (Ra-SBRT) technique offers a therapeutic advantage by delivering focal irradiation to metastatic lung lesions and reduces the bystander toxicity to normal tissues. We have previously demonstrated that Ra-SBRT ablates metastatic lesions and induces tumor immune rejection of metastatic tumors by promoting in situ programming of M2 TAM towards M1-TAM and infiltration of Siglec-8+ Eosinophils. Most interestingly, Ra SBRT has very low abscopal impact and spares normal tissues, which are the significant limitations with conventional radiotherapy. In view of this and Immune adjuvant potential of Ra SBRT, it promotes normalization of aberrant vasculature and inhibits the metastatic potential of NSCLC lesions. In view of this we here propose that Ra-SBRT indeed represents an immunogenic approach for the effective management of advanced-stage NSCLC.

How Macrophages Become Transcriptionally Dysregulated: A Hidden Impact of Antitumor Therapy

Tumor-associated macrophages (TAMs) are the essential components of the tumor microenvironment. TAMs originate from blood monocytes and undergo pro- or anti-inflammatory polarization during their life span within the tumor. The balance between macrophage functional populations and the efficacy of their antitumor activities rely on the transcription factors such as STAT1, NF-κB, IRF, and others. These molecular tools are of primary importance, as they contribute to the tumor adaptations and resistance to radio- and chemotherapy and can become important biomarkers for theranostics. Herein, we describe the major transcriptional mechanisms specific for TAM, as well as how radio- and chemotherapy can impact gene transcription and functionality of macrophages, and what are the consequences of the TAM-tumor cooperation.

The Immune Tolerance Role of the HMGB1-RAGE Axis

The disruption of the immune tolerance induces autoimmunity such as systemic lupus erythematosus and vasculitis. A chromatin-binding non-histone protein, high mobility group box 1 (HMGB1), is released from the nucleus to the extracellular milieu in particular environments such as autoimmunity, sepsis and hypoxia. Extracellular HMGB1 engages pattern recognition receptors, including Toll-like receptors (TLRs) and the receptor for advanced glycation endproducts (RAGE). While the HMGB1-RAGE axis drives inflammation in various diseases, recent studies also focus on the anti-inflammatory effects of HMGB1 and RAGE. This review discusses current perspectives on HMGB1 and RAGE's roles in controlling inflammation and immune tolerance. We also suggest how RAGE heterodimers responding microenvironments functions in immune responses.

Biology of NSCLC: Interplay between Cancer Cells, Radiation and Tumor Immune Microenvironment

The overall prognosis and survival of non-small cell lung cancer (NSCLC) patients remain poor. The immune system plays an integral role in driving tumor control, tumor progression, and overall survival of NSCLC patients. While the tumor cells possess many ways to escape the immune system, conventional radiotherapy (RT) approaches, which are directly cytotoxic to tumors, can further add additional immune suppression to the tumor microenvironment by destroying many of the lymphocytes that circulate within the irradiated tumor environment. Thus, the current immunogenic balance, determined by the tumor- and radiation-inhibitory effects is significantly shifted towards immunosuppression, leading to poor clinical outcomes. However, newer emerging evidence suggests that tumor immunosuppression is an "elastic process" that can be manipulated and converted back into an immunostimulant environment that can actually improve patient outcome. In this review we will discuss the natural immunosuppressive effects of NSCLC cells and conventional RT approaches, and then shift the focus on immunomodulation through novel, emerging immuno- and RT approaches that promise to generate immunostimulatory effects to enhance tumor control and patient outcome. We further describe some of the mechanisms by which these newer approaches are thought to be working and set the stage for future trials and additional preclinical work.