Pathophysiological Role of Histamine H4 Receptor in Cancer: Therapeutic Implications

The story of clobenpropit and CXCR4: can be an effective drug in cancer and autoimmune diseases?

Clobenpropit is a histamine H3 receptor antagonist and has developed as a potential therapeutic drug due to its ability to inhibit CXCR4, a chemokine receptor involved in autoimmune diseases and cancer pathogenesis. The CXCL12/CXCR4 axis involves several biological phenomena, including cell proliferation, migration, angiogenesis, inflammation, and metastasis. Accordingly, inhibiting CXCR4 can have promising clinical outcomes in patients with malignancy or autoimmune disorders. Based on available knowledge, Clobenpropit can effectively regulate the release of monocyte-derived inflammatory cytokine in autoimmune diseases such as juvenile idiopathic arthritis (JIA), presenting a potential targeted target with possible advantages over current therapeutic approaches. This review summarizes the intricate interplay between Clobenpropit and CXCR4 and the molecular mechanisms underlying their interactions, comprehensively analyzing their impact on immune regulation. Furthermore, we discuss preclinical and clinical investigations highlighting the probable efficacy of Clobenpropit for managing autoimmune diseases and cancer. Through this study, we aim to clarify the immunomodulatory role of Clobenpropit and its advantages and disadvantages as a novel therapeutic opportunity.

The role of histamine and its receptors in breast cancer: from pathology to therapeutic targets

Breast cancer is the most common malignancy in women, and despite the development of new treatment methods and the decreasing mortality rate in recent years, one of the clinical problems in breast cancer treatment is chronic inflammation in the tumor microenvironment. Histamine, an inflammatory mediator, is produced by tumor cells and can induce chronic inflammation and the growth of some tumors by recruiting inflammatory cells. It can also affect tumor physiopathology, antitumor treatment efficiency, and patient survival. Antihistamines, as histamine receptor antagonists, play a role in modulating the effects of these receptors in tumor cells and can affect some treatment methods for breast cancer therapy; in this review, we investigate the role of histamine, its receptors, and antihistamines in breast cancer pathology and treatment methods.

Therapeutic potential of LINS01 histamine H3 receptor antagonists as antineoplastic agents for triple negative breast cancer

The aims of this work were to evaluate the expression of histamine H3 receptor (H3R) in triple negative breast cancer (TNBC) samples and to investigate the antitumoral efficacy and safety of the LINS01 series of H3R antagonists, through in silico, in vitro, and in vivo approaches. Antitumor activity of LINS01009, LINS01010, LINS01022, LINS01023 was assayed in vitro in 4T1 and MDA-MB-231 TNBC cells (0.01-100 μM), and in vivo in 4T1 tumors orthotopically established in BALB/c mice (1 or 20 mg/kg). Additionally, H3R expression was assessed in 50 human TNBC samples. We have described a higher H3R mRNA expression in basal-like/TNBC tumors vs. matched normal tissue using TCGA Pan-Cancer Atlas data, and a higher H3R expression in human tumor samples vs. peritumoral tissue evidenced by immunohistochemistry associated with poorer survival. Furthermore, while all the essayed compounds showed antitumoral properties, LINS01022 and LINS01023 exhibited the most potent antiproliferative effects by: i) inducing cell apoptosis and suppressing cell migration in 4T1 and MDA-MB-231 TNBC cells, and ii) inhibiting cell growth in paclitaxel-resistant 4T1 cells (potentiating the paclitaxel antiproliferative effect). Moreover, 20 mg/kg LINS01022 reduced tumor size in 4T1 tumor-bearing mice, exhibiting a safe toxicological profile and potential for druggability estimated by ADME calculations. We conclude that the H3R is involved in the regulation of TNBC progression, offering promising therapeutic potential for the novel LINS01 series of H3R antagonists.

Trafficking of carbonic anhydrase 12 and bicarbonate transporters by histamine stimulation mediates intracellular acidic scenario in lung cancer cells

Carbonic anhydrase 12 is considered an oncogenic and acidic microenvironmental factor in cancer cells. To verify the role of histamine signalling as an anti-cancer signal, we determined the roles of CA12 and its associated bicarbonate transporters. In this study, histamine stimulation mediated mislocalization of CA12 in lung cancer cells. Histamine receptor activation-mediated CA12 endocytosis and pH were restored by CaMKII inhibition. CA12-associated AE2 expression was enhanced, whereas NBCn1 expression and its activity were reduced by histamine stimulation. Histamine receptor activation-mediated acidification was induced by internalised CA12 and NBCn1 and, at the same time by increased bicarbonate efflux through enhanced AE2 expression. Inhibition of protein trafficking by bafilomycin restored CA12 and AE2 localisation and diminished cellular acidosis. Thus, we verified that histamine stimulation induced an acidic scenario, which revealed trafficking of CA12 and its associated bicarbonate transporters in lung cancer cells and its dysregulated pH modulation may be involved in the histamine signalling-mediated anti-cancer process.

Histamine H4 Receptor Antagonist Ameliorates the Progression of Experimental Autoimmune Encephalomyelitis via Regulation of T-Cell Imbalance

Multiple sclerosis (MS) is a degenerative condition characterized by immune-mediated attacks on the central nervous system (CNS), resulting in demyelination and recurring T-cell responses. The histamine H4 receptor (H4R) is mainly expressed in cellular populations and plays a vital role in inflammation and immunological responses. The role of H4R in neurons of the CNS has recently been revealed. However, the precise role of H4R in neuronal function remains inadequately understood. The objective of this work was to investigate the impact of JNJ 10191584 (JNJ), a highly effective and specific H4R antagonist, on the development of experimental autoimmune encephalomyelitis (EAE) and to gain insight into the underlying mechanism involved. In this study, we examined the potential impact of JNJ therapy on the course of EAE in SJL/J mice. EAE mice were administered an oral dose of JNJ at a concentration of 6 mg/kg once a day, starting from day 10 and continuing until day 42. Afterward, the mice's clinical scores were assessed. In this study, we conducted additional research to examine the impact of JNJ on several types of immune cells, specifically Th1 (IFN-γ and T-bet), Th9 (IL-9 and IRF4), Th17 (IL-17A and RORγt), and regulatory T (Tregs; Foxp3 and TGF-β1) cells in the spleen. In this study, we further investigated the impact of JNJ on the mRNA expression levels of IFN-γ, T-bet, IL-9, IRF4, IL-17A, RORγt, Foxp3, and TGF-β1 in the brain. Daily treatment of JNJ effectively reduced the development of EAE in mice. The percentages of CD4+IFN-γ+, CD4+T-bet+, CD4+IL-9+, CD4+IRF4+, CD4+IL-17A+, and CD4+RORγt+ cells were shown to decrease, whereas the percentages of CD4+TGF-β1+ and CD4+Foxp3+ cells were observed to increase in EAE mice treated with JNJ. Therefore, the HR4 antagonist positively affected the course of EAE by modulating the signaling of transcription factors. The identified results include possible ramifications in the context of MS treatment.

Histamine H4 Receptor Agonist, 4-Methylhistamine, Aggravates Disease Progression and Promotes Pro-Inflammatory Signaling in B Cells in an Experimental Autoimmune Encephalomyelitis Mouse Model

We sought to assess the impact of 4-Methylhistamine (4-MeH), a specific agonist targeting the Histamine H4 Receptor (H4R), on the progression of experimental autoimmune encephalomyelitis (EAE) and gain insight into the underlying mechanism. EAE is a chronic autoimmune, inflammatory, and neurodegenerative disease of the central nervous system (CNS) characterized by demyelination, axonal damage, and neurodegeneration. Over the past decade, pharmacological research into the H4R has gained significance in immune and inflammatory disorders. For this study, Swiss Jim Lambert EAE mice were treated with 4-MeH (30 mg/kg/day) via intraperitoneal administration from days 14 to 42, and the control group was treated with a vehicle. Subsequently, we evaluated the clinical scores. In addition, flow cytometry was employed to estimate the impact of 4-Methylhistamine (4-MeH) on NF-κB p65, GM-CSF, MCP-1, IL-6, and TNF-α within CD19+ and CXCR5+ spleen B cells. Additionally, we investigated the effect of 4-MeH on the mRNA expression levels of Nf-κB p65, Gmcsf, Mcp1, Il6, and Tnfα in the brain of mice using RT-PCR. Notably, the clinical scores of EAE mice treated with 4-MeH showed a significant increase compared with those treated with the vehicle. The percentage of cells expressing CD19+NF-κB p65+, CXCR5+NF-κB p65+, CD19+GM-CSF+, CXCR5+GM-CSF+, CD19+MCP-1+, CXCR5+MCP-1+, CD19+IL-6+, CXCR5+IL-6+, CD19+TNF-α+, and CXCR5+TNF-α+ exhibited was more pronounced in 4-MeH-treated EAE mice when compared to vehicle-treated EAE mice. Moreover, the administration of 4-MeH led to increased expression of NfκB p65, Gmcsf, Mcp1, Il6, and Tnfα mRNA in the brains of EAE mice. This means that the H4R agonist promotes pro-inflammatory mediators aggravating EAE symptoms. Our results indicate the harmful role of H4R agonists in the pathogenesis of MS in an EAE mouse model.

Novel therapeutic targets to halt the progression of Parkinson's disease: an in-depth review on molecular signalling cascades

Recent research has focused mostly on understanding and combating the neurodegenerative mechanisms and symptoms of Parkinson's disease (PD). Moreover, developing novel therapeutic targets to halt the progression of PD remains a key focus for researchers. As yet, no agents have been found to have unambiguous evidence of disease-modifying actions in PD. The primary objective of this review is to summarize the promising targets that have recently been uncovered which include histamine 4 receptors, beta2 adrenergic receptor, phosphodiesterase 4, sphingosine-1-phosphate receptor subtype 1, angiotensin receptors, high-mobility group box 1, rabphilin-3A, purinergic 2Y type 12 receptor, colony-stimulating factor-1 receptor, transient receptor potential vanilloid 4, alanine-serine-cysteine transporter 2, G protein-coupled oestrogen receptor, a mitochondrial antiviral signalling protein, glucocerebrosidase, indolamine-2,3-dioxygenase-1, soluble epoxy hydroxylase and dual specificity phosphatase 6. We have also reviewed the molecular signalling cascades of those novel targets which cause the initiation and progression of PD and gathered some emerging disease-modifying agents that could slow the progression of PD. These approaches will assist in the discovery of novel target molecules, for curing disease symptoms and may provide a glimmer of hope for the treatment of PD. As of now, there is no drug available that will completely prevent the progression of PD by inhibiting the pathogenesis involved in PD, and thus, the newer targets and their inhibitors or activators are the major focus for researchers to suppress PD symptomatology. And the major limitations of these targets are the lack of clinical data and less number pre-clinical data, as we have majorly discussed the different targets which all have well reported for other disease pathogenesis. Thus, finding the disease-drug interactions, the molecular mechanisms, and the major side effects will be major challenges for the researchers.

Current and novel approaches in the pharmacological treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most lethal malignant tumours worldwide. The mortality-to-incidence ratio is up to 91.6% in many countries, representing the third leading cause of cancer-related deaths. Systemic drugs, including the multikinase inhibitors sorafenib and lenvatinib, are first-line drugs used in HCC treatment. Unfortunately, these therapies are ineffective in most cases due to late diagnosis and the development of tumour resistance. Thus, novel pharmacological alternatives are urgently needed. For instance, immune checkpoint inhibitors have provided new approaches targeting cells of the immune system. Furthermore, monoclonal antibodies against programmed cell death-1 have shown benefits in HCC patients. In addition, drug combinations, including first-line treatment and immunotherapy, as well as drug repurposing, are promising novel therapeutic alternatives. Here, we review the current and novel pharmacological approaches to fight HCC. Preclinical studies, as well as approved and ongoing clinical trials for liver cancer treatment, are discussed. The pharmacological opportunities analysed here should lead to significant improvement in HCC therapy.

Treatment of allergy: Overview of synthetic anti-allergy small molecules in medicinal chemistry

The prevalence of allergic diseases has been continuously increasing over the past few decades, affecting approximately 20-30% of the global population. Allergic reactions to infection of respiratory tract, digestive tract, and skin system involve multiple different targets. The main difficulty of anti-allergy research is how to develop drugs with good curative effect and less side effects by adopting new multi-targets and mechanisms according to the clinical characteristics of different allergic populations and different allergens. This review focuses on information concerning potential therapeutic targets as well as the synthetic anti-allergy small molecules with respect to their medicinal chemistry. The structure-activity relationship and the mechanism of compound-target interaction were highlighted with perspective to histamine-1/4 receptor antagonists, leukotriene biosynthesis, Th2 cytokines inhibitors, and calcium channel blockers. We hope that the study of chemical scaffold modification and optimization for different lead compounds summarized in this review not only lays the foundation for improvement of success rate and efficiency of virtual screening of antiallergic drugs, but also can provide valuable reference for the drug design of related promising research such as allergy, inflammation, and cancer.

Lamin-A/C Is Modulated by the Involvement of Histamine-Mediated Calcium/Calmodulin-Dependent Kinase II in Lung Cancer Cells

Lamins are nuclear envelope proteins involved in various cellular functions, such as DNA modulation, cellular differentiation, and development. In this study, we investigate the role of histamine in lung cancer biology. Since it is known that lamin-A/C is negatively regulated in lung cancer, we hypothesize that histamine signaling is related to nuclear lamin-A/C regulation and cancer progression. Our findings reveal that histamine stimulation enhances lamin-A/C expression in lung cancer cells. Lamin-A/C expression is dependent on histamine-mediated intracellular calcium signaling and subsequent calcium/calmodulin-dependent kinase II (Ca/CaMKII) activation. The nuclear protein nestin, which stabilizes lamin-A/C expression, is also modulated by Ca/CaMKII. However, histamine-mediated lamin-A/C expression is independent of Akt/focal adhesion kinase or autophagy signaling. Histamine stimulation attenuates lung cancer motility in the presence of enhanced lamin-A/C expression. In conclusion, we propose a regulatory mechanism that accounts for the modulation of lamin-A/C levels through the involvement of Ca/CaMKII in cancer cells and provides molecular evidence of histamine signaling in lamin-A/C biology.

Histamine H4 Receptor Expression in Triple-negative Breast Cancer: An Exploratory Study

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype. There are neither universally accepted prognostic markers nor molecular targets related to TNBC. The histamine H4 receptor (H4R) has been characterized in TNBC experimental models, demonstrating its critical role in tumor development and progression. In this study, H4R expression was compared in breast cancer subtypes and correlated with clinical features using The Cancer Genome Atlas data (Pan-Cancer Atlas). The H4R status was further evaluated by immunohistochemistry in 30 TNBC human samples in relation to clinicopathological parameters. Results indicate that H4R was downregulated in basal-like/TNBC compared with luminal A and normal breast-like tumors. The higher expression of H4R was associated with improved progression-free and overall survival outcomes in basal-like/TNBC. H4R immunoreactivity was detected in about 70% of tumors, and its expression was positively correlated with the levels in the histologically normal peritumoral tissue. High H4R expression in peritumoral tissue correlated with reduced number of lymph node involvement and unifocal TNBC, while it was associated with increased patient survival. In conclusion, the H4R might represent a potential prognostic biomarker in TNBC. Further studies in large cohorts are needed to better understand the significance of H4R in breast cancer biology.

Serum Metabolic Disturbances in Lung Cancer Investigated through an Elaborative NMR-Based Serum Metabolomics Approach

Detection of metabolic disturbances in lung cancer (LC) has the potential to aid early diagnosis/prognosis and hence improve disease management strategies through reliable grading, staging, and determination of neoadjuvant status in LC. However, a majority of previous metabolomics studies compare the normalized spectral features which not only provide ambiguous information but further limit the clinical translation of this information. Various such issues can be resolved by performing the concentration profiling of various metabolites with respect to formate as an internal reference using commercial software Chenomx. Continuing our efforts in this direction, the serum metabolic profiles were measured on 39 LC patients and 42 normal controls (NCs, comparable in age/sex) using high-field 800 MHz NMR spectroscopy and compared using multivariate statistical analysis tools to identify metabolic disturbances and metabolites of diagnostic potential. Partial least-squares discriminant analysis (PLS-DA) model revealed a distinct separation between LC and NC groups and resulted in excellent discriminatory ability with the area under the receiver-operating characteristic (AUROC) = 0.97 [95% CI = 0.89-1.00]. The metabolic features contributing to the differentiation of LC from NC samples were identified first using variable importance in projection (VIP) score analysis and then checked for their statistical significance (with p-value < 0.05) and diagnostic potential using the ROC curve analysis. The analysis revealed relevant metabolic disturbances associated with LC. Among various circulatory metabolites, six metabolites, including histidine, glutamine, glycine, threonine, alanine, and valine, were found to be of apposite diagnostic potential for clinical implications. These metabolic alterations indicated altered glucose metabolism, aberrant fatty acid synthesis, and augmented utilization of various amino acids including active glutaminolysis in LC.

Histamine H4 Receptor Agonism Induces Antitumor Effects in Human T-Cell Lymphoma

The discovery of the human histamine H4 receptor (H4R) has contributed to our understanding of the role of histamine in numerous physiological and pathological conditions, including tumor development and progression. The lymph nodes of patients with malignant lymphomas have shown to contain high levels of histamine, however, less is known regarding the expression and function of the H4R in T-cell lymphoma (TCL). In this work we demonstrate the expression of H4R isoforms (mRNA and protein) in three human aggressive TCL (OCI-Ly12, Karpas 299, and HuT78). Histamine and specific H4R agonists (VUF8430 and JNJ28610244) significantly reduced cell viability in a dose-dependent manner (p < 0.05). The combined treatment with the H4R antagonist (JNJ7777120, 10 µM) reversed the effects of the H4R ligands. Importantly, we screened a drug repurposing library of 433 FDA-approved compounds (1 μM) in combination with histamine (10 μM) in Hut78 cells. Histamine produced a favorable antitumor effect with 18 of these compounds, including the histone deacetylase inhibitor panobinostat. Apoptosis, proliferation, and oxidative stress studies confirmed the antitumoral effects of the combination. We conclude that the H4R is expressed in TCL, and it is involved in histamine-mediated responses.

Variances in the Expression of mRNAs and miRNAs Related to the Histaminergic System in Endometrioid Endometrial Cancer

Research has indicated higher concentrations of histamine and polyamine in endometrioid tissue in comparison with healthy tissue. The aim of this study was to evaluate changes in the expression patterns of messenger RNA (mRNAs) and microRNA (miRNAs) related to the histaminergic system in endometrial samples and whole blood in women with endometrioid endometrial cancer. The study group consisted of 30 women with endometrioid endometrial cancer qualified for hysterectomy (G1 well-differentiated, 15 cases; G2 moderately differentiated, 8 cases; and G3 poorly differentiated, 7 cases). The control group included 30 women with no neoplastic changes during routine gynecological examinations. The molecular analysis consisted of the microarray analysis of mRNAs and miRNAs related to the histaminergic system, reverse-transcription quantitative polymerase chain reaction (RTqPCR), and enzyme-linked immunosorbent assay (ELISA). Out of 65 mRNAs connected with the histaminergic system, 10 differentiate the samples of tissue and blood obtained from patients with endometrioid endometrial cancer in comparison with the control group (p < 0.05). mRNA histamine receptor 1,3 (HRH1, HRH3), and solute carrier family 22 member 3 (SLC23A2) differentiating samples of endometrioid endometrial cancer independent of either G or control. The highest probability of interaction, based on the target score miRDB, between the selected miRNAs and mRNAs was found for the hybrids hsa-miR-1-3p and endothelin 1 (END1), hsa-miR-27a-5β and SLC23A2. The selected mRNA and miRNA transcripts seem to be promising for molecularly targeted therapies in the context of endometrioid endometrial cancer.

Histamine in cancer immunology and immunotherapy. Current status and new perspectives

Cancer is the second leading cause of death globally and its incidence and mortality are rapidly increasing worldwide. The dynamic interaction of immune cells and tumor cells determines the clinical outcome of cancer. Immunotherapy comes to the forefront of cancer treatments, resulting in impressive and durable responses but only in a fraction of patients. Thus, understanding the characteristics and profiles of immune cells in the tumor microenvironment (TME) is a necessary step to move forward in the design of new immunomodulatory strategies that can boost the immune system to fight cancer. Histamine produces a complex and fine-tuned regulation of the phenotype and functions of the different immune cells, participating in multiple regulatory responses of the innate and adaptive immunity. Considering the important actions of histamine-producing immune cells in the TME, in this review we first address the most important immunomodulatory roles of histamine and histamine receptors in the context of cancer development and progression. In addition, this review highlights the current progress and foundational developments in the field of cancer immunotherapy in combination with histamine and pharmacological compounds targeting histamine receptors.

Pathophysiological Roles of Histamine Receptors in Cancer Progression: Implications and Perspectives as Potential Molecular Targets

High levels of histamine and histamine receptors (HRs), including H1R~H4R, are found in many different types of tumor cells and cells in the tumor microenvironment, suggesting their involvement in tumor progression. This review summarizes the latest evidence demonstrating the pathophysiological roles of histamine and its cognate receptors in cancer biology. We also discuss the novel therapeutic approaches of selective HR ligands and their potential prognostic values in cancer treatment. Briefly, histamine is highly implicated in cancer development, growth, and metastasis through interactions with distinct HRs. It also regulates the infiltration of immune cells into the tumor sites, exerting an immunomodulatory function. Moreover, the effects of various HR ligands, including H1R antagonists, H2R antagonists, and H4R agonists, on tumor progression in many different cancer types are described. Interestingly, the expression levels of HR subtypes may serve as prognostic biomarkers in several cancers. Taken together, HRs are promising targets for cancer treatment, and HR ligands may offer novel therapeutic potential, alone or in combination with conventional therapy. However, due to the complexity of the pathophysiological roles of histamine and HRs in cancer biology, further studies are warranted before HR ligands can be introduced into clinical settings.

Identification of TYROBP and FCER1G as Key Genes with Prognostic Value in Clear Cell Renal Cell Carcinoma by Bioinformatics Analysis

The involvement of aberrantly expressed genes in the pathogenesis and progression of various human malignancies has been widely reported, including clear cell renal cell carcinoma (ccRCC). This study aimed to identify potential crucial genes in ccRCC and further investigate the role of these genes in ccRCC prognosis. Three gene expression profiles (GSE3, GSE6344 and GSE53000) were downloaded from GEO database. GEO2R was performed to identify the differentially expressed genes (DEGs) between ccRCC and normal samples. GO analysis and KEGG pathway enrichment analysis were applied for the function analysis. The DEGs were mapped into the PPI network, then the hub genes were identified and verified using the ONCOMINE database. Kaplan-Meier plotter was used to evaluate of the prognostic value of the identified hub genes. A total of 113 DEGs were identified from the three gene expression profiles, including 64 up-regulated genes and 69 down-regulated genes. DEGs were observed to be enriched in biological processes related to the progress and pathogenesis of human cancers. According to PPI network, 5 hub genes were collected, including TYROBP, C1QB, ITGB2, CD53 and FCER1G. Among them, CD53 was newly identified, and Kaplan-Meier survival curves suggested that high expression of CD53 was significantly associated with poor survival in ccRCC patients (log-rank P < 0.01). The present results may provide new insight into the understanding of molecular mechanisms and the clinical prognosis of ccRCC.

Molecular Modeling of Histamine Receptors-Recent Advances in Drug Discovery

The recent developments of fast reliable docking, virtual screening and other algorithms gave rise to discovery of many novel ligands of histamine receptors that could be used for treatment of allergic inflammatory disorders, central nervous system pathologies, pain, cancer and obesity. Furthermore, the pharmacological profiles of ligands clearly indicate that these receptors may be considered as targets not only for selective but also for multi-target drugs that could be used for treatment of complex disorders such as Alzheimer's disease. Therefore, analysis of protein-ligand recognition in the binding site of histamine receptors and also other molecular targets has become a valuable tool in drug design toolkit. This review covers the period 2014-2020 in the field of theoretical investigations of histamine receptors mostly based on molecular modeling as well as the experimental characterization of novel ligands of these receptors.

Impact of histamine H4 receptor deficiency on the modulation of T cells in a murine breast cancer model

BACKGROUND

The histamine H4 receptor (H4R) is preferentially expressed in immune cells and is a potential therapeutic target for inflammatory and autoimmune diseases. This study aimed at further exploring the role of H4R in the immunobiology of breast cancer.

METHODS

We used wild type (WT) and H4R deficient mice (KO) to evaluate whether H4R genotypes show a different distribution of T cell subsets in spleens, tumours and tumour draining lymph nodes (TDLN) in a syngeneic ErbB2-positive breast cancer model developed orthotopically with LM3 cells and its impact on tumour growth.

RESULTS

The presence of tumours had a differential impact on the distribution of T cells in TDLN from KO mice compared to WT ones. At day 21 post-inoculation (p.i.) of cells, despite no significant changes in the tumour weight, TDLN from KO mice showed a significantly increased proportion of CD8⁺ T cells compared to WT mice. At day 38 p.i. of cells a reduced tumour weight was evident in KO mice. This was accompanied by a decreased proportion of CD4⁺CD25⁺FoxP3⁺ regulatory T cells in TDLN of KO compared to WT mice. Tumour-bearing KO mice showed a better survival compared to WT mice.

CONCLUSIONS

H4R-mediated mechanisms may modulate the immune tumour microenvironment, promoting an immunosuppressive milieu. Results suggest that H4R could be explored as an immunotherapeutic target with potential benefit in combination with immunotherapy. Further preclinical and clinical studies are necessary to confirm this hypothesis.

Nothing to sneeze at: Histamine and histamine receptors in oral carcinogenesis

Oral squamous cell carcinoma (OSCC), the most common oral malignancy, shows an increasing rate of incidence worldwide. In spite of the recent advances in cancer research, OSCC therapy continues to have unfavourable outcomes, and thus, patient's prognosis remains relatively poor. Current research has been devoted to identifying novel therapeutic targets also in the tumour microenvironment (TME). Histamine and its G-protein-coupled receptors (H1R-H4R) play vital roles in multiple cancer-associated processes in TME, where histamine is mainly produced by mast cells. However, oral epithelial cells were recently shown to produce low concentrations of histamine in autocrine and paracrine modes. These findings, together with the discovery of the high-affinity histamine H4 receptor, have led to a massive increase in our understanding of histamine functions. In this review, we aim to summarize the most recent findings regarding histamine and its receptors and their involvement in oral carcinogenesis-from oral potentially malignant disorders (OPMDs) to invasive OSCC. Importantly, histamine receptors are differentially expressed in OPMDs and OSCC. Furthermore, H1R and H4R are associated with clinicopathological characteristics of OSCC patients, suggesting a role in prognosis. Due to the enormous success of histamine-based medications, histamine receptors may also represent promising and viable drug targets in oral cancer.

Histamine H3 Receptor Promotes Cell Survival via Regulating PKA/CREB/CDKN1A Signal Pathway in Hepatocellular Carcinoma

Background

The histamine H3 receptor (HRH3) is mainly expressed in areas of the brain involved in the regulation of the release of various neurotransmitters. Recent studies have shown that HRH3 expression is increased in several types of carcinomas. However, the functional roles and underlying molecular mechanism by which HRH3 regulates cell survival in hepatocellular carcinoma (HCC) remain unknown.

Methods

The mRNA and protein expression level of target genes were evaluated by qRT-PCR, Western blot and immunohistochemistry, respectively. Cell viability and cell proliferation activity were assessed by MTS assay and EdU incorporation assay. Cell apoptosis and cell cycle were assessed by flow cytometry analysis. A xenograft mouse model was constructed to investigate the effect of HRH3 on tumor growth in vivo.

Results

Our results indicated that HRH3 was significantly upregulated in HCC, which promoted cell survival by accelerating cell proliferation and inhibiting cell apoptosis. Our results also showed that HRH3 in HCC downregulated the expression of cyclin-dependent kinase inhibitor p21 (CDKN1A) to promote G1-S phase transition by inactivating the cAMP/PKA/CREB pathway, which finally contributed to the malignant growth of HCC.

Conclusion

Our findings indicated that HRH3 functioned in promoting HCC survival by inactivating the cAMP/PKA/CREB pathway to downregulate CDKN1A expression. Thus, HRH3 might serve as a potential therapeutic target in HCC treatment.

Differential Role of Serines and Threonines in Intracellular Loop 3 and C-Terminal Tail of the Histamine H4 Receptor in β-Arrestin and G Protein-Coupled Receptor Kinase Interaction, Internalization, and Signaling

The histamine H₄ receptor (H₄R) activates Gα_i-mediated signaling and recruits β-arrestin2 upon stimulation with histamine. β-Arrestins play a regulatory role in G protein-coupled receptor (GPCR) signaling by interacting with phosphorylated serine and threonine residues in the GPCR C-terminal tail and intracellular loop 3, resulting in receptor desensitization and internalization. Using bioluminescence resonance energy transfer (BRET)-based biosensors, we show that G protein-coupled receptor kinases (GRK) 2 and 3 are more quickly recruited to the H₄R than β-arrestin1 and 2 upon agonist stimulation, whereas receptor internalization dynamics toward early endosomes was slower. Alanine-substitution revealed that a serine cluster at the distal end of the H₄R C-terminal tail is essential for the recruitment of β-arrestin1/2, and consequently, receptor internalization and desensitization of G protein-driven extracellular-signal-regulated kinase (ERK)1/2 phosphorylation and label-free cellular impedance. In contrast, alanine substitution of serines and threonines in the intracellular loop 3 of the H₄R did not affect β-arrestin2 recruitment and receptor desensitization, but reduced β-arrestin1 recruitment and internalization. Hence, β-arrestin recruitment to H₄R requires the putative phosphorylated serine cluster in the H₄R C-terminal tail, whereas putative phosphosites in the intracellular loop 3 have different effects on β-arrestin1 versus β-arrestin2. Mutation of these putative phosphosites in either intracellular loop 3 or the C-terminal tail did not affect the histamine-induced recruitment of GRK2 and GRK3 but does change the interaction of H₄R with GRK5 and GRK6, respectively. Identification of H₄R interactions with these proteins is a first step in the understanding how this receptor might be dysregulated in pathophysiological conditions.

Study of the antitumour effects and the modulation of immune response by histamine in breast cancer

BACKGROUND

The aim of this work was to improve the knowledge of the role of histamine in breast cancer by assessing the therapeutic efficacy of histamine and histamine H4 receptor (H4R) ligands in a triple-negative breast cancer (TNBC) model developed in immunocompetent hosts. By using publicly available genomic data, we further investigated whether histidine decarboxylase (HDC) could be a potential biomarker.

METHODS

Tumours of 4T1 TNBC cells were orthotopically established in BALB/c mice. Treatments employed (mg kg^-1): histamine (1 and 5), JNJ28610244 (H4R agonist, 1 and 5) and JNJ7777120 (H4R antagonist, 10).

RESULTS

Increased HDC gene expression is associated with better relapse-free and overall survival in breast cancer patients. Histamine treatment (5 mg kg^-1) of 4T1 tumour-bearing mice reduced tumour growth and increased apoptosis. Although no immunomodulatory effects were observed in wild-type mice, significant correlations between tumour weight and cytotoxic lymphocyte infiltration were detected in H4R knockout mice. H4R agonist or antagonist differentially modulated tumour growth and immunity in 4T1 tumour-bearing mice.

CONCLUSIONS

Histamine plays a complex role and stands out as a promising drug for TNBC treatment, which deserves to be tested in clinical settings. HDC expression level is associated with clinicopathological characteristics, suggesting a prognostic value in breast cancer.