Harnessing the alarmin HMGN1 for anticancer therapy

Identification of immunogenic cell death-related damage-related molecular patterns (DAMPs) to predict outcomes in patients with head and neck squamous cell carcinoma

PURPOSE

Head and neck cancer is the sixth most common type of cancer worldwide, wherein the immune responses are closely associated with disease occurrence, development, and prognosis. Investigation of the role of immunogenic cell death-related genes (ICDGs) in adaptive immune response activation may provide cues into the mechanism underlying the outcome of HNSCC immunotherapy.

METHODS

ICDGs expression patterns in HNSCC were analyzed, after which consensus clustering in HNSCC cohort conducted. A 4-gene prognostic model was constructed through LASSO and Cox regression analyses to analyze the prognostic index using the TCGA dataset, followed by validation with two GEO datasets. The distribution of immune cells and the response to immunotherapy were compared between different risk subtypes through multiple algorithms. Moreover, immunohistochemical (IHC) analyses were conducted to validate the prognostic value of HSP90AA1 as a predictor of HNSCC patient prognosis. In vitro assays were performed to further detect the effect of HSP90AA1 in the development of HNSCC.

RESULTS

A novel prognostic index based on four ICDGs was constructed and proved to be useful as an independent factor of HNSCC prognosis. The risk score derived from this model grouped patients into high- and low-risk subtypes, wherein the high-risk subtype had worse survival outcomes and poorer immunotherapy response. IHC analysis validated the applicability of HSP90AA1 as a predictor of prognosis of HNSCC patients. HSP90AA1 expression in tumor cells promotes the progression of HNSCC.

CONCLUSIONS

Together, these results highlight a novel four-gene prognostic signature as a valuable tool to assess survival status and prognosis of HNSCC patients.

Shaking up the silence: consequences of HMGN1 antagonizing PRC2 in the Down syndrome brain

Intellectual disability is a well-known hallmark of Down Syndrome (DS) that results from the triplication of the critical region of human chromosome 21 (HSA21). Major studies were conducted in recent years to gain an understanding about the contribution of individual triplicated genes to DS-related brain pathology. Global transcriptomic alterations and widespread changes in the establishment of neural lineages, as well as their differentiation and functional maturity, suggest genome-wide chromatin organization alterations in trisomy. High Mobility Group Nucleosome Binding Domain 1 (HMGN1), expressed from HSA21, is a chromatin remodeling protein that facilitates chromatin decompaction and is associated with acetylated lysine 27 on histone H3 (H3K27ac), a mark correlated with active transcription. Recent studies causatively linked overexpression of HMGN1 in trisomy and the development of DS-associated B cell acute lymphoblastic leukemia (B-ALL). HMGN1 has been shown to antagonize the activity of the Polycomb Repressive Complex 2 (PRC2) and prevent the deposition of histone H3 lysine 27 trimethylation mark (H3K27me3), which is associated with transcriptional repression and gene silencing. However, the possible ramifications of the increased levels of HMGN1 through the derepression of PRC2 target genes on brain cell pathology have not gained attention. In this review, we discuss the functional significance of HMGN1 in brain development and summarize accumulating reports about the essential role of PRC2 in the development of the neural system. Mechanistic understanding of how overexpression of HMGN1 may contribute to aberrant brain cell phenotypes in DS, such as altered proliferation of neural progenitors, abnormal cortical architecture, diminished myelination, neurodegeneration, and Alzheimer's disease-related pathology in trisomy 21, will facilitate the development of DS therapeutic approaches targeting chromatin.

Combining an Alarmin HMGN1 Peptide with PD-L1 Blockade Results in Robust Antitumor Effects with a Concomitant Increase of Stem-Like/Progenitor Exhausted CD8+ T Cells

The expansion of intratumoral stem-like/progenitor exhausted CD8⁺ T (Tstem/Tpex) cells provides a potential approach to improve the therapeutic efficacy of immune checkpoint blockade (ICB). Thus, here we demonstrate a strategy to facilitate Tstem/Tpex cell expansion by combining an alarmin high-mobility group nucleosome binding domain 1 (HMGN1) peptide with programmed death-ligand 1 (PD-L1) blockade. The antitumor effects of HMGN1, anti-PD-L1, and their combined treatment were monitored in the B16F10, LLC, Colon26, or EO771 tumor-bearing mice. The comprehensive immunologic analyses, such as high-dimensional flow cytometry, transcriptome analysis, and single-cell RNA-sequencing (scRNA-seq), were used to investigate the cellular and molecular mechanisms of antitumor immune responses after treatments. We identified the immunostimulatory domain (EPKRR SARLS AKPPA KVEAK PKK) on HMGN1 and synthesized this domain as a therapeutic peptide (minP1). Combined treatment with minP1 and PD-L1 blockade induced durable tumor regression in tumor-bearing mice. minP1 increased the number of intratumoral mature DCs enriched in immunoregulatory molecules (mregDC) and enhanced their MHC class I antigen-presenting program. minP1 also synergized with PD-L1 blockade in augmenting intratumoral Tstem/Tpex cell number. Analysis of our scRNA-seq dataset by CellPhonDB suggested potential interactions between mregDCs and Tstem/Tpex cells in tumors. Our results indicate that HMGN1 peptide (minP1) serves as an immunoadjuvant to promote effective anti-PD-L1 immunotherapy with increased Tstem/Tpex cells in tumors.

Alarmin-painted exosomes elicit persistent antitumor immunity in large established tumors in mice

Treating large established tumors is challenging for dendritic cell (DC)-based immunotherapy. DC activation with tumor cell-derived exosomes (TEXs) carrying multiple tumor-associated antigen can enhance tumor recognition. Adding a potent adjuvant, high mobility group nucleosome-binding protein 1 (HMGN1), boosts DCs’ ability to activate T cells and improves vaccine efficiency. Here, we demonstrate that TEXs painted with the functional domain of HMGN1 (TEX-N1ND) via an exosomal anchor peptide potentiates DC immunogenicity. TEX-N1ND pulsed DCs (DC_TEX-N1ND) elicit long-lasting antitumor immunity and tumor suppression in different syngeneic mouse models with large tumor burdens, most notably large, poorly immunogenic orthotopic hepatocellular carcinoma (HCC). DC_TEX-N1ND show increased homing to lymphoid tissues and contribute to augmented memory T cells. Importantly, N1ND-painted serum exosomes from cancer patients also promote DC activation. Our study demonstrates the potency of TEX-N1ND to strengthen DC immunogenicity and to suppress large established tumors, and thus provides an avenue to improve DC-based immunotherapy.

The use of tumour exosome-activated dendritic cell (DC) immunotherapy shows promise for the treatment of large established tumours. Here, the authors generate alarmin HMGN1-attached tumour exosomes which significantly improve therapy efficacy by boosting DC activation in several preclinical mouse models.

Biological Functions of HMGN Chromosomal Proteins

Chromatin plays a key role in regulating gene expression programs necessary for the orderly progress of development and for preventing changes in cell identity that can lead to disease. The high mobility group N (HMGN) is a family of nucleosome binding proteins that preferentially binds to chromatin regulatory sites including enhancers and promoters. HMGN proteins are ubiquitously expressed in all vertebrate cells potentially affecting chromatin function and epigenetic regulation in multiple cell types. Here, we review studies aimed at elucidating the biological function of HMGN proteins, focusing on their possible role in vertebrate development and the etiology of disease. The data indicate that changes in HMGN levels lead to cell type-specific phenotypes, suggesting that HMGN optimize epigenetic processes necessary for maintaining cell identity and for proper execution of specific cellular functions. This manuscript contains tables that can be used as a comprehensive resource for all the English written manuscripts describing research aimed at elucidating the biological function of the HMGN protein family.

High-Mobility Group Nucleosome-Binding Protein 1 Mediates Renal Fibrosis Correlating with Macrophages Accumulation and Epithelial-to-Mesenchymal Transition in Diabetic Nephropathy Mice Model

Background/Aim: Renal fibrosis is essential for the progression of diabetic nephropathy (DN). Macrophages accumulate in diabetic kidneys and are involved in epithelial-to-mesenchymal transition (EMT), a vital mechanism leading to renal fibrosis. Recently, high-mobility group nucleosome-binding protein 1(HMGN1) was documented in promoting the recruitment and activation of antigen-presenting cells. In this study, we first reported its roles in renal fibrosis and the underlying mechanism associated with macrophage filtration and EMT. Methods: Twenty C57BL/6J mice were administered streptozotocin (STZ) to induce diabetes for 6 weeks and then divided into 4 groups: normal control group; DN group; benazepril-treated group, and insulin-treated group. Blood glucose, creatinine, and albumin in urine, hematoxylin and eosin, and Sirius red staining of kidney tissues were used to assess the renal pathology. ELISA, immunochemistry, and in situ hybridization were performed to determine the expression of HMGN1, CD68, F4/80, α-smooth muscle actin, and E-cadherin. Results: The renal expression levels of HMGN1, macrophage markers, and EMT makers were increased in DN group, and insulin treatment could reduce the overexpression of these indicators with a better effect than benazepril treatment. Both treatments could not obviously ameliorate urine albumin-to-creatinine ratio, collagen expression, and renal histological changes in STZ-induced diabetic mice. Correlation analysis indicated that there was a relationship among HMGN1, macrophage markers, EMT markers, and collagen expression in DN mice. Conclusion: HMGN1 may promote macrophages accumulation and EMT, suggesting a potential therapeutic target for preventing renal fibrosis development in DN.

Inhibition of murine hepatoma tumor growth by cryptotanshinone involves TLR7-dependent activation of macrophages and induction of adaptive antitumor immune defenses

Cryptotanshinone (CT), a purified compound initially isolated from the dried roots of Salvia militorrhiza. Bunge, exhibits cytotoxic antitumor effects on many tumors. We have shown that CT possesses the dual capacities to concomitantly inhibit the proliferation of lung cancer cells and promote the generation of antitumor immunity. In this study, we investigated whether CT could be used to treat hepatocellular carcinoma (HCC) using a mouse Hepa1-6 model. CT inhibited the proliferation of mouse hepatoma (Hepa1-6) cells in vitro by inducing Hepa1-6 cells apoptosis through the JAK2/STAT3 signaling pathway. In addition, CT activated macrophages and polarized mouse bone marrow-derived macrophages (BMM) toward an M1 phenotype in vitro, which depended on the TLR7/MyD88/NF-κB signaling pathway. Furthermore, CT significantly inhibited the growth of syngeneic Hepa1-6 hepatoma tumors, and, in combination with anti-PD-L1 cured Hepa1-6-bearing mice with the induction of long-term anti-Hepa1-6 specific immunity. Immunoprofiling of treated Hepa1-6-bearing mice revealed that CT-promoted activation of tumor-infiltrating macrophages and dendritic cells, induction of antitumor T cell response, and infiltration of effector/memory CD8 T cells in the tumor tissue. Importantly, the immunotherapeutic effects of CT and anti-PD-L1 depended on the presence of CD8 T cells. Thus, CT and anti-PD-L1 may provide an effective immunotherapeutic regimen for human HCC based on a combination of cytotoxic effects and induction of tumor-specific immunity.

Alarmin augments the antitumor immunity of lentiviral vaccine in ectopic, orthotopic and autochthonous hepatocellular carcinoma mice

It is a daunting therapeutic challenge to completely eradicate hepatocellular carcinoma (HCC) from patients. Alpha-fetoprotein (AFP) -based vaccines appear promising, however the efficacy needs to be improved.

Methods: Here, we explore if fusing high-mobility group nucleosome binding protein 1 (HMGN1), a potent immunoadjuvant, to AFP (lenti-HA) can augment the antitumor immunity of AFP-expressing lentiviral vector (lenti-AFP), a vehicle extensively employed for genetic immunization with high transduction efficacy and good safety profiles. The antitumor immunity of Lenti-HA was systemically assessed in ectopic, orthotopic and autochthonous HCC models.

Results: Lenti-HA elicited strong anti-HCC effects in mice and amplified the antitumor immunity of lenti-AFP by reducing effective dose 6-fold. Importantly, lenti-HA induced a robust antitumor immune response with prolonged survival rate and improved the immune and tumor microenvironment in mice with carcinogen-induced autochthonous HCC. Lenti-HA localized primarily to lymphoid organs with no preference for specific immune cell types. Activated dendritic cells (DCs), particularly CD103⁺CD11b^- DCs, were also actively recruited to lymph nodes in lenti-HA-treated HCC mice. Moreover, lenti-HA-transduced human DCs elicited stronger immune response than lenti-AFP against HCC cells in vitro.

Conclusion: Our study demonstrates that HMGN1 augments the antitumor immunity of AFP-expressing lentiviral vaccines in HCC mice and human cells in vitro and thus provides a new therapeutic strategy for HCC.

Combined treatment with HMGN1 and anti-CD4 depleting antibody reverses T cell exhaustion and exerts robust anti-tumor effects in mice

BACKGROUND

Transient depletion of CD4⁺ T cells results in tumor suppression and survival benefit in murine models; however, the tumor progression and recurrence still occur over more long-term monitoring of mice. Thus, we explored an additional strategy to enhance endogenous immune responses by an alarmin, high mobility group nucleosome binding protein 1 (HMGN1).

METHODS

The anti-tumor effects of HMGN1, anti-CD4 depleting antibody, and their combined treatment were monitored in the Colon26 or the B16F10 subcutaneous murine models. The tumor-infiltrating CD8⁺ T cell proliferation, differentiation, exhaustion, and its gene expression were determined by flow cytometry, transcriptome analysis, and quantitative real-time PCR.

RESULTS

Our results show that a systemic administration of low doses of HMGN1 with an anti-CD4 depleting antibody (HMGN1/αCD4) promoted expansion of CD8⁺ T cell populations (e.g. CD137⁺ PD-1⁺ and CD44^hi PD-1⁺), recruited CCR7⁺ migratory dendritic cells to the tumor, and reduced co-inhibitory molecules (e.g. PD-1, LAG-3, and TIM-3) to counteract CD8⁺ T cell exhaustion.

CONCLUSION

The HMGN1/αCD4 treatment expanded effector CD8⁺ T cells and prolonged their anti-tumor activities by rescuing them from exhaustion, thus resulting in tumor regression and even rejection in long-term monitored mice.

High-mobility group nucleosome binding domain 1 (HMGN1) functions as a Th1-polarizing alarmin

High-mobility group (HMG) nucleosome binding domain 1 (HMGN1), which previously was thought to function only as a nucleosome-binding protein that regulates chromatin structure, histone modifications, and gene expression, was recently discovered to be an alarmin that contributes extracellularly to the generation of innate and adaptive immune responses. HMGN1 promotes DC recruitment through interacting with a Gαi protein-coupled receptor (GiPCR) and activates DCs predominantly through triggering TLR4. HMGN1 preferentially promotes Th1-type immunity, which makes it relevant for the fields of vaccinology, autoimmunity, and oncoimmunology. Here, we discuss the alarmin properties of HMGN1 and update recent advances on its roles in immunity and potential applications for immunotherapy of tumors.

Alarmins and immunity

More than a decade has passed since the conceptualization of the "alarmin" hypothesis. The alarmin family has been expanding in terms of both number and the concept. It has recently become clear that alarmins play important roles as initiators and participants in a diverse range of physiological and pathophysiological processes such as host defense, regulation of gene expression, cellular homeostasis, wound healing, inflammation, allergy, autoimmunity, and oncogenesis. Here, we provide a general view on the participation of alarmins in the induction of innate and adaptive immune responses, as well as their contribution to tumor immunity.