Role of ADGRG1/GPR56 in Tumor Progression

Novel diagnostic biomarker and immune profiling of GPR56+ B cell subsets in systemic lupus erythematosus

GPR56, a member of the adhesion G-protein-coupled receptor family, is a marker of cytotoxic lymphocytes and plays diverse roles in physiological and pathological processes. However, its role in peripheral blood B cells of systemic lupus erythematosus (SLE) patients remains unclear. This study investigates GPR56 expression in peripheral blood B cells from 30 SLE patients and 21 healthy controls, focusing on its clinical diagnostic potential. Flow cytometry revealed significantly higher GPR56 expression in SLE patients, particularly in plasmablasts. RNA sequencing identified upregulation of immune-related molecules, including CD28, CD226, and cytotoxic effectors (GZMB, GNLY, IL-1β) in GPR56+ B cells, indicating enhanced immune activity. Additionally, GPR56+ B cells proportions correlated with clinical indicators such as anti-U1RNP antibodies and IgM levels. ROC curve analysis demonstrated the diagnostic value of GPR56+ B cells and related subsets, with AUC values ranging from 0.6754 to 0.8377. In conclusion, GPR56+ B cells may serve as valuable biomarkers for SLE diagnosis and contribute to understanding the disease's immune dysregulation.

Serum analytes as predictors of disease recurrence and the duration of invasive disease-free survival in patients with triple negative breast cancer enrolled in the OXEL trial treated with immunotherapy, chemotherapy, or chemoimmunotherapy

BACKGROUND

The OXEL study (NCT03487666) was a phase II trial of patients with triple negative breast cancer (TNBC) with residual disease following neoadjuvant chemotherapy, randomized to receive immunotherapy (anti-programmed cell death protein 1, nivolumab), chemotherapy (capecitabine), or chemoimmunotherapy. We previously reported on the primary endpoint of the OXEL trial, demonstrating that a peripheral immunoscore based on circulating immune cells reflecting immune activation was increased in patients treated with immunotherapy. However, compared with cell-based immune assays, sera assays are more cost-effective, less labor-intensive, and samples easier to obtain. Here, we report on differences in serum analytes between treatment arms and associations with clinical response.

METHODS

Patients (n=38) were assayed for 97 serum analytes before and after 6 and 12 weeks of therapy. Serum analytes were assessed for changes with therapy, and as predictors of disease recurrence and the duration of invasive disease-free survival (iDFS) in both single analyte analyses and machine learning models.

RESULTS

Levels of specific analytes at baseline and changes in levels at early time points on treatment preceding recurrence were associated with eventual development of disease recurrence and/or the duration of iDFS. These associations varied based on the therapy patients received. Immunotherapy led to enrichment in pro-inflammatory analytes following treatment, whereas chemotherapy resulted in overall decreases. Changes seen in patients receiving chemoimmunotherapy more closely resembled those observed in patients receiving immunotherapy alone as opposed to chemotherapy alone. Furthermore, logistic regression and Cox proportional hazard models, developed using machine learning methods, demonstrated that combinations of serum analytes were more predictive of disease recurrence and iDFS duration than analyses of single serum analytes. Notably, the multivariable models that predicted patient outcomes were highly specific to the class of treatment patients received.

CONCLUSIONS

In patients with TNBC with residual disease after neoadjuvant chemotherapy, treatment with immunotherapy alone or chemoimmunotherapy resulted in enhanced immune activation compared with chemotherapy alone as measured by changes in serum analyte levels. Distinct serum analytes, both at baseline and as changes after therapy, predicted clinical outcomes for patients receiving immunotherapy alone, chemotherapy alone, or chemoimmunotherapy.

TRIAL REGISTRATION NUMBER

NCT03487666.

The colorectal cancer microenvironment: Preclinical progress in identifying targets for cancer therapy

Colorectal cancer (CRC) is a common cancer with high mortality rates. Despite progress in treatment, it remains an incurable disease for many patients. In CRC, the tumor microenvironment (TME) plays critical roles in tumor growth, progression, patients' prognosis, and response to treatments. Understanding TME complexities is important for developing effective therapies. In vitro and in vivo preclinical models are critical in understanding the disease, discovering potential targets, and developing effective therapeutics. In this review, we focus on preclinical research studies associated with modulation of the TME in CRC. These models give insights into understanding the role of stroma and immune cell components of the TME in CRC and improve clinical responses, providing insights in novel treatment options. Various studies have focused on targeting the TME in CRC to improve responses to different therapeutic approaches. These include identifying targets for cancer therapies, targeting molecular signaling, and enhancing the efficacy of immunotherapeutic modalities. Furthermore, targeting stromal and angiogenic factors in the TME may provide new therapeutic options. Overall, understanding and targeting the TME in CRC is a promising approach for improving therapeutic outcomes.

Identification of biomarkers for tumor regression grade in esophageal squamous cell carcinoma patients after neoadjuvant chemoradiotherapy

Background

Esophageal cancer is a highly invasive malignancy. Neoadjuvant chemoradiotherapy not only increases the rate of complete resection but also improves the median survival. However, a sensitive biomarker is urgently needed in clinical practice.

Methods

60 esophageal squamous cell carcinoma (ESCC) patients undergoing neoadjuvant chemoradiotherapy (NCRT) were enrolled at the People's Hospital Affiliated to Jiangsu University. Patients were grouped according to tumor regression grade (TRG) criteria from the College of American Pathologists (CAP). The correlation between TRG groups, clinicopathologic characteristics, and prognosis was analyzed. Differential gene expression analysis was performed on ESCC patients before and after NCRT using the public database (GSE43519). MMP9, NFIX, and GPR56 were identified as candidate genes, and their expression and correlation with prognosis were evaluated by immunohistochemical analysis.

Results

Among 60 ESCC patients who underwent surgery after NCRT, the pathological complete response (pCR) rate was 35.0% (21/60), and the major pathological response (MPR) rate was 60.0% (36/60). Poor tumor differentiation and neural or vascular invasion were associated with inadequate tumor regression grade and were independent factors influencing TRG. ESCC patients were divided into effective (TRG 0 + 1) and ineffective (TRG 2 + 3) groups. Higher TRG was significantly associated with shorter overall survival (OS). Our study also identified TRG as an independent prognostic factor through univariate and multivariate Cox regression analyses (P < 0.05). The differentially expressed genes GPR56, MMP9, and NFIX selected from the GSE43519 dataset were significantly downregulated after NCRT (P < 0.001). Immunohistochemistry showed that GPR56 was highly expressed in ESCC, while it was negatively expressed in paracancerous tissues. There was a significant difference in expression between cancerous and paracancerous tissues. GPR56 expression was consistent with the public dataset, and patients with high GPR56 expression had significantly shorter OS (P < 0.05). In addition, patients with inadequate MPR and high GPR56 expression had shorter OS (P < 0.05).

Conclusions

The findings suggest that TRG serves as an independent prognostic factor for ESCC following NCRT. High GPR56 expression is found to be associated with a poor prognosis of ESCC. Downregulation of GPR56 suggests a potential significant predictive value in conjunction with MPR analysis.

GPR56 facilitates hepatocellular carcinoma metastasis by promoting the TGF-β signaling pathway

The metastasis of hepatocellular carcinoma (HCC) poses a significant threat to the survival of patients. G protein-coupled receptor 56 (GPR56) has garnered extensive attention within malignant tumor research and plays a crucial role in cellular surface signal transmission. Nonetheless, its precise function in HCC remains ambiguous. Our investigation reveals a notable rise in GPR56 expression levels in human HCC cases, with heightened GPR56 levels correlating with unfavorable prognoses. GPR56 regulates TGF-β pathway by interacting with TGFBR1, thereby promoting HCC metastasis. At the same time, GPR56 is subject to regulation by the canonical cascade of TGF-β signaling, thereby establishing a positive feedback loop. Furthermore, the combination application of TGFBR1 inhibitor galunisertib (GAL) and GPR56 inhibitor Dihydromunduletone (DHM), significantly inhibits HCC metastasis. Interventions towards this signaling pathway could offer a promising therapeutic approach to effectively impede the metastasis of GPR56-mediated HCC.

Role of G protein coupled receptors in acute kidney injury

Acute kidney injury (AKI) is a clinical condition characterized by a rapid decline in kidney function, which is associated with local inflammation and programmed cell death in the kidney. The G protein-coupled receptors (GPCRs) represent the largest family of signaling transduction proteins in the body, and approximately 40% of drugs on the market target GPCRs. The expressions of various GPCRs, prostaglandin receptors and purinergic receptors, to name a few, are significantly altered in AKI models. And the role of GPCRs in AKI is catching the eyes of researchers due to their distinctive biological functions, such as regulation of hemodynamics, metabolic reprogramming, and inflammation. Therefore, in this review, we aim to discuss the role of GPCRs in the pathogenesis of AKI and summarize the relevant clinical trials involving GPCRs to assess the potential of GPCRs and their ligands as therapeutic targets in AKI and the transition to AKI-CKD.

A correlation study of adhesion G protein-coupled receptors as potential therapeutic targets for breast cancer

BACKGROUND

Adhesion G protein-coupled receptors (aGPCRs), a distinctive subset of the G protein-coupled receptor (GPCR) superfamily, play crucial roles in various physiological and pathological processes, with implications in tumor development. Despite the global prevalence of breast cancer (BRCA), specific aGPCRs as potential drug targets or biomarkers remain underexplored.

METHODS

UALCAN, GEPIA, Kaplan-Meier Plotter, MethSurv, cBiopportal, String, GeneMANIA, DAVID, Timer, Metascape, and qPCR were applied in this work.

RESULTS

Our analysis revealed significantly increased transcriptional levels of ADGRB2, ADGRC1, ADGRC2, ADGRC3, ADGRE1, ADGRF2, ADGRF4, and ADGRL1 in BRCA primary tumors. Further analysis indicated a significant correlation between the expressions of certain aGPCRs and the pathological stage of BRCA. High expression of ADGRA1, ADGRF2, ADGRF4, ADGRG1, ADGRG2, ADGRG4, ADGRG6, and ADGRG7 was significantly correlated with poor overall survival (OS) in BRCA patients. Additionally, high expression of ADGRF2 and ADGRF4 indicated inferior recurrence-free survival (RFS) in BRCA patients. The RT-qPCR experiments also confirmed that the mRNA levels of ADGRF2 and ADGRF4 were higher in BRCA cells and tissues. Functional analysis highlighted the diverse roles of aGPCRs, encompassing GPCR signaling and metabolic energy reserves. Moreover, aGPCRs may exert influence or actively participate in the development of BRCA through their impact on immune status.

CONCLUSION

aGPCRs, particularly ADGRF2 and ADGRF4, hold promise as immunotherapeutic targets and prognostic biomarkers in BRCA.

G protein coupled receptor in apoptosis and apoptotic cell clearance

Apoptosis is a genetically programmed form of cell death that is substantially conserved across the evolutionary tree. Apoptotic cell elimination includes recognition, phagocytosis, and degradation. Failure to clear apoptotic cells can ultimately cause a series of human diseases, such as systemic lupus erythematosus, Alzheimer's disease, atherosclerosis, and cancer. Consequently, the timely and effective removal of apoptotic cells is crucial to maintaining the body's homeostasis. GPCRs belong to the largest membrane receptor family. Its intracellular domain exerts an effect on the trimer G protein. By combining with a variety of ligands, the extracellular domain of G protein initiates the dissociation of G protein trimers and progressively transmits signals downstream. Presently, numerous G protein-coupled receptors (GPCRs) have been identified as participants in the apoptosis signal transduction pathway and the apoptotic cell clearance pathway. Therefore, studies on the mechanism of GPCRs in the clearance of apoptotic cells is important for the development of GPCRs therapeutics.

GPR56: A potential therapeutic target for neurological and psychiatric disorders

GPR56, also known as GPR56/ADGRG1, is a member of the ADGRG subgroup belonging to adhesion G protein-coupled receptors (aGPCRs). aGPCRs are the second largest subfamily of the GPCR superfamily, which is the largest family of membrane protein receptors in the human genome. Studies in recent years have demonstrated that GPR56 is integral to the normal development of the brain and functions as an important player in cortical development, suggesting that GPR56 is involved in many physiological processes. Indeed, aberrant expression of GPR56 has been implicated in multiple neurological and psychiatric disorders, including bilateral frontoparietal polymicrogyria (BFPP), depression and epilepsy. In a recent study, it was found that upregulated expression of GPR56 reduced depressive-like behaviours in an animal model of depression, indicating that GPR56 plays an important role in the antidepressant response. Given the link of GPR56 with the antidepressant response, the function of GPR56 has become a focus of research. Although GPR56 may be a potential target for the development of antidepressants, the underlying molecular mechanisms remain largely unknown. Therefore, in this review, we will summarize the latest findings of GPR56 function in neurological and psychiatric disorders (depression, epilepsy, autism, and BFPP) and emphasize the mechanisms of GPR56 in activation and signalling in those conditions. After reviewing several studies, attributing to its significant biological functions and exceptionally long extracellular N-terminus that interacts with multiple ligands, we draw a conclusion that GPR56 may serve as an important drug target for neuropsychological diseases.

Former smoking associated with epigenetic modifications in human granulosa cells among women undergoing assisted reproduction

Smoking exposure during adulthood can disrupt oocyte development in women, contributing to infertility and possibly adverse birth outcomes. Some of these effects may be reflected in epigenome profiles in granulosa cells (GCs) in human follicular fluid. We compared the epigenetic modifications throughout the genome in GCs from women who were former (N = 15) versus never smokers (N = 44) undergoing assisted reproductive technologies (ART). This study included 59 women undergoing ART. Smoking history including time since quitting was determined by questionnaire. GCs were collected during oocyte retrieval and DNA methylation (DNAm) levels were profiled using the Infinium MethylationEPIC BeadChip. We performed an epigenome-wide association study with robust linear models, regressing DNAm level at individual loci on smoking status, adjusting for age, ovarian stimulation protocol, and three surrogate variables. We performed differentially methylated regions (DMRs) analysis and over-representation analysis of the identified CpGs and corresponding gene set. 81 CpGs were differentially methylated among former smokers compared to never smokers (FDR < 0.05). We identified 2 significant DMRs (KCNQ1 and RHBDD2). The former smoking-associated genes were enriched in oxytocin signaling, adrenergic signaling in cardiomyocytes, platelet activation, axon guidance, and chemokine signaling pathway. These epigenetic variations have been associated with inflammatory responses, reproductive outcomes, cancer development, neurodevelopmental disorder, and cardiometabolic health. Secondarily, we examined the relationships between time since quitting and DNAm at significant CpGs. We observed three CpGs in negative associations with the length of quitting smoking (p < 0.05), which were cg04254052 (KCNIP1), cg22875371 (OGDHL), and cg27289628 (LOC148145), while one in positive association, which was cg13487862 (PLXNB1). As a pilot study, we demonstrated epigenetic modifications associated with former smoking in GCs. The study is informative to potential biological pathways underlying the documented association between smoking and female infertility and biomarker discovery for smoking-associated reproductive outcomes.

GPR56, an Adhesion GPCR with Multiple Roles in Human Diseases, Current Status and Future Perspective

Human G protein-coupled receptor 56 (GPR56) belongs to a member of the adhesion G-protein coupled receptor (aGPCR) family and widely exists in the central nervous system and various types of tumor tissues. Recent studies have shown that abnormal expression or dysfunction of GPR56 is closely associated with many physiological and pathological processes, including brain development, neuropsychiatric disorders, cardiovascular diseases and cancer progression. In addition, GPR56 has been proven to enhance the susceptibility of some antipsychotics and anticarcinogens in response to the treatment of neuropsychological diseases and cancer. Although there have been some reports about the functions of GPR56, the underlying mechanisms implicated in these diseases have not been clarified thoroughly, especially in depression and epilepsy. Therefore, in this review, we described the molecular structure and signal transduction pathway of GPR56 and carried out a comprehensive summary of GPR56's function in the development of psychiatric disorders and cancer. Our review showed that GPR56 deficiency led to depressive-like behaviors and an increase in resistance to antipsychotic treatment. In contrast, the upregulation of GPR56 contributed to tumor cell proliferation and metastasis in malignant diseases such as glioblastoma, colorectal cancer, and ovarian cancer. Moreover, we elucidated specific signaling pathways downstream of GPR56 related to the pathogenesis of these diseases. In summary, our review provides compelling arguments for an attractive therapeutic target of GPR56 in improving the therapeutic efficiency for patients suffering from psychiatric disorders and cancer.

An integrated analysis of bulk and single-cell sequencing data reveals that EMP1+/COL3A1+ fibroblasts contribute to the bone metastasis process in breast, prostate, and renal cancers

Introduction

Bone metastasis (BoM) occurs when cancer cells spread from their primary sites to a bone. Currently, the mechanism underlying this metastasis process remains unclear.

Methods

In this project, through an integrated analysis of bulk-sequencing and single-cell RNA transcriptomic data, we explored the BoM-related features in tumor microenvironments of different tumors.

Results

We first identified 34 up-regulated genes during the BoM process in breast cancer, and further explored their expression status among different components in the tumor microenvironment (TME) of BoM samples. Enriched EMP1+ fibroblasts were found in BoM samples, and a COL3A1-ADGRG1 communication between these fibroblasts and cancer cells was identified which might facilitate the BoM process. Moreover, a significant correlation between EMP1 and COL3A1 was identified in these fibroblasts, confirming the potential connection of these genes during the BoM process. Furthermore, the existence of these EMP1+/COL3A1+ fibroblasts was also verified in prostate cancer and renal cancer BoM samples, suggesting the importance of these fibroblasts from a pan-cancer perspective.

Discussion

This study is the first attempt to investigate the relationship between fibroblasts and BoM process across multi-tumor TMEs. Our findings contribute another perspective in the exploration of BoM mechanism while providing some potential targets for future treatments of tumor metastasis.

Re-routing GPR56 signalling using Gα12/13 G protein chimeras

Adhesion G protein-coupled receptors (aGPCRs) constitute the second largest subclass of the GPCR superfamily. Although canonical GPCRs are explored pharmacologically as drug targets, no clinically approved drugs target the aGPCR family so far. The aGPCR GPR56/ADGRG1 stands out as an especially promising target, given its direct link to the monogenetic disease bilateral frontoparietal polymicrogyria and implications in cancers. Key to understanding GPCR pharmacology has been mapping out intracellular signalling activity. Detection of GPCR signalling in the Gαs /Gαi /Gαq G protein pathways is feasible with second messenger detection systems. However, in the case of Gα12/13 -coupled receptors, like GPR56, signalling detection is more challenging due to the lack of direct second messenger generation. To overcome this challenge, we engineered a Gαq chimera to translate Gα12/13 signalling. We show the ability of the chimeric GαΔ6q12myr and GαΔ6q13myr to translate basal Gα12/13 signalling of GPR56 to a Gαq readout in transcription factor luciferase reporter systems and show that the established peptide ligands (P7 and P19) function to enhance this signal. We further demonstrate the ability to directly influence the generation of second messengers in inositol-3-phosphate assays. In the future, these chimeric G proteins could facilitate basic functional studies, drug screenings and deorphanization of other aGPCRs.

Quantitative Evaluation of Stem-like Markers of Human Glioblastoma Using Single-Cell RNA Sequencing Datasets

Targeting glioblastoma (GBM) stem-like cells (GSCs) is a common interest in both the laboratory investigation and clinical treatment of GBM. Most of the currently applied GBM stem-like markers lack validation and comparison with common standards regarding their efficiency and feasibility in various targeting methods. Using single-cell RNA sequencing datasets from 37 GBM patients, we obtained a large pool of 2173 GBM stem-like marker candidates. To evaluate and select these candidates quantitatively, we characterized the efficiency of the candidate markers in targeting the GBM stem-like cells by their frequencies and significance of being the stem-like cluster markers. This was followed by further selection based on either their differential expression in GBM stem-like cells compared with normal brain cells or their relative expression level compared with other expressed genes. The cellular location of the translated protein was also considered. Different combinations of selection criteria highlight different markers for different application scenarios. By comparing the commonly used GSCs marker CD133 (PROM1) with markers selected by our method regarding their universality, significance, and abundance, we revealed the limitations of CD133 as a GBM stem-like marker. Overall, we propose BCAN, PTPRZ1, SOX4, etc. for laboratory-based assays with samples free of normal cells. For in vivo targeting applications that require high efficiency in targeting the stem-like subtype, the ability to distinguish GSCs from normal brain cells, and a high expression level, we recommend the intracellular marker TUBB3 and the surface markers PTPRS and GPR56.

Roles of Focal Adhesion Kinase PTK2 and Integrin αIIbβ3 Signaling in Collagen- and GPVI-Dependent Thrombus Formation under Shear

Glycoprotein (GP)VI and integrin αIIbβ3 are key signaling receptors in collagen-dependent platelet aggregation and in arterial thrombus formation under shear. The multiple downstream signaling pathways are still poorly understood. Here, we focused on disclosing the integrin-dependent roles of focal adhesion kinase (protein tyrosine kinase 2, PTK2), the shear-dependent collagen receptor GPR56 (ADGRG1 gene), and calcium and integrin-binding protein 1 (CIB1). We designed and synthetized peptides that interfered with integrin αIIb binding (pCIB and pCIBm) or mimicked the activation of GPR56 (pGRP). The results show that the combination of pGRP with PTK2 inhibition or of pGRP with pCIB > pCIBm in additive ways suppressed collagen- and GPVI-dependent platelet activation, thrombus buildup, and contraction. Microscopic thrombus formation was assessed by eight parameters (with script descriptions enclosed). The suppressive rather than activating effects of pGRP were confined to blood flow at a high shear rate. Blockage of PTK2 or interference of CIB1 no more than slightly affected thrombus formation at a low shear rate. Peptides did not influence GPVI-induced aggregation and Ca2+ signaling in the absence of shear. Together, these data reveal a shear-dependent signaling axis of PTK2, integrin αIIbβ3, and CIB1 in collagen- and GPVI-dependent thrombus formation, which is modulated by GPR56 and exclusively at high shear. This work thereby supports the role of PTK2 in integrin αIIbβ3 activation and signaling.