Effect of functional genetic variants in chemokine decoy receptors on the recurrence risk of breast cancer

Atypical chemokine receptor 4 (ACKR4/CCX-CKR): A comprehensive exploration across physiological and pathological landscapes in contemporary research

Atypical chemokine receptor 4 (ACKR4), also known as CCX-CKR, is a member of the chemokine receptor family that lacks typical G protein signaling activity. Instead, ACKR4 functions as a scavenger receptor that can bind and internalize a wide range of chemokines, influencing their availability and activity in the body. ACKR4 is involved in various physiological processes, such as immune cell trafficking and the development of thymus, spleen, and lymph nodes. Moreover, ACKR4 has been implicated in several pathological conditions, including cancer, heart and lung diseases. In cancer, ACKR4 plays a complex role, acting as a tumor suppressor or promoter depending on the type of cancer and the stage of the disease. For instance, ACKR4 may inhibit the growth and metastasis of breast cancer, but it may also promote the progression of hepatocellular carcinoma and gastric cancer. In inflammatory situations, ACKR4 has been found to modulate the recruitment and activation of immune cells, contributing to the pathogenesis of diseases such as myocardial infraction and pulmonary sarcoidosis. The study of ACKR4 is still ongoing, and further research is needed to fully understand its role in different physiological and pathological contexts. Nonetheless, ACKR4 represents a promising target for the development of novel therapeutic strategies for various diseases.

Atypical chemokine receptors in cancer

Atypical chemokine receptors (ACKRs) are a group of seven-transmembrane spanning serpentine receptors that are structurally homologous to classical G-protein-coupled receptors and bind cognate chemokines with high affinities but do not signal via G-proteins or mediate cell migration. However, ACKRs efficiently modify the availability and function of chemokines in defined microanatomical environments, can signal via intracellular effectors other than G-proteins, and play complex roles in physiology and disease, including in cancer. In this review, we summarize the findings on the diverse contributions of individual ACKRs to cancer development, progression, and tumor-host interactions. We discuss how changes in ACKR expression within tumor affect cancer growth, tumor vascularization, leukocyte infiltration, and metastasis formation, ultimately resulting in differential disease outcomes. Across many studies, ACKR3 expression was shown to support tumor growth and dissemination, whereas ACKR1, ACKR2, and ACKR4 in tumors were more likely to contribute to tumor suppression. With few notable exceptions, the insights on molecular and cellular mechanisms of ACKRs activities in cancer remain sparse, and the intricacies of their involvement are not fully appreciated. This is particularly true for ACKR1, ACKR2 and ACKR4. A better understanding of how ACKR expression and functions impact cancer should pave the way for their future targeting by new and effective therapies.

Involvement in Tumorigenesis and Clinical Significance of CXCL1 in Reproductive Cancers: Breast Cancer, Cervical Cancer, Endometrial Cancer, Ovarian Cancer and Prostate Cancer

C-X-C motif chemokine ligand 1 (CXCL1) is a member of the CXC chemokine subfamily and a ligand for CXCR2. Its main function in the immune system is the chemoattraction of neutrophils. However, there is a lack of comprehensive reviews summarizing the significance of CXCL1 in cancer processes. To fill this gap, this work describes the clinical significance and participation of CXCL1 in cancer processes in the most important reproductive cancers: breast cancer, cervical cancer, endometrial cancer, ovarian cancer, and prostate cancer. The focus is on both clinical aspects and the significance of CXCL1 in molecular cancer processes. We describe the association of CXCL1 with clinical features of tumors, including prognosis, ER, PR and HER2 status, and TNM stage. We present the molecular contribution of CXCL1 to chemoresistance and radioresistance in selected tumors and its influence on the proliferation, migration, and invasion of tumor cells. Additionally, we present the impact of CXCL1 on the microenvironment of reproductive cancers, including its effect on angiogenesis, recruitment, and function of cancer-associated cells (macrophages, neutrophils, MDSC, and T_reg). The article concludes by summarizing the significance of introducing drugs targeting CXCL1. This paper also discusses the significance of ACKR1/DARC in reproductive cancers.

CCL2/ACKR2 interaction participate in breast cancer metastasis especially in patients with altered lipid metabolism

Breast cancer is the most prevalent cancer worldwide and metastasis accounts for the majority of associated deaths. Altered lipid metabolism has been proved to be involved with breast cancer, yet the underlying mechanism in lipid metabolism mediated metastasis in breast cancer remains inadequately understood. Evidence have indicated that adipocytes can produce chemokine ligand 2 (CCL2), and several studies have shown that tumor metastasis and patient survival is associated with atypical chemokine receptors/chemokine decoy receptors. We are interested in the factors that may influence cancer metastasis and patient prognosis, particularly in patients with altered lipid metabolism. In this paper, we propose a hypothesis that patients with increased expression levels of atypical chemokine receptor 2 (ACKR2) receptors will have less chance for tumor metastasis, whereas patients with decreased ACKR2 expression but high levels of chemokine receptor 2 positive (CCR2 + ) monocytes are more likely to develop metastasis and have worse outcomes. However, in patients with lower ACKR2 expression level but elevated level of CCR2 + NK cells, primary tumor can be suppressed and therefore present better outcomes.

Atypical chemokine receptor ACKR2-V41A has decreased CCL2 binding, scavenging, and activation, supporting sustained inflammation and increased Alzheimer's disease risk

A recent genome-wide association study (GWAS) of 59 cerebrospinal fluid (CSF) proteins with a connection to Alzheimer's disease (AD) demonstrated an association between increased levels of chemokine ligand 2 (CCL2) with an atypical chemokine receptor chemokine-binding protein 2 variant V41A (ACKR2-V41A; rs2228467). High levels of CCL2 are associated with increased risk of AD development as well as other inflammatory diseases. In this study we characterized the biological function of the ACKR2-V41A receptor compared to the wild type allele by measuring its ligand binding affinity, CCL2 scavenging efficiency, and cell activation sensitivity. We transfected Chinese hamster ovary cells with plasmids carrying wild type ACKR2 (ACKR2-WT) or the mutant ACKR2-V41A receptor. Binding affinity assays showed that ACKR2-V41A has a lower binding affinity for CCL2 and CCL4 than ACKR2-WT. CCL2 scavenging results aligned with binding affinity assays, with ACKR2-V41A cells scavenging CCL2 with a lower efficiency than ACKR2-WT. Cell activation assays also showed that ACKR2-V41A cells had significantly lower receptor upregulation (β-Arrestin-dependent signaling pathway) upon stimulation compared to ACKR2-WT cells. These findings provide molecular and biological mechanistic insights into the GWAS association of ACKR2-V41A with increased levels of CCL2 in CSF and possibly other chemokine ligands. Increased CCL2 levels are associated with accelerated cognitive decline and increased risk of AD. Understanding how this atypical chemokine receptor allele increases serum markers of inflammation could lead to novel therapeutic solutions for AD.

The diverse and complex roles of atypical chemokine receptors in cancer: From molecular biology to clinical relevance and therapy

Chemokines regulate directed cell migration, proliferation and survival and are key components in cancer biology. They exert their functions by interacting with seven-transmembrane domain receptors that signal through G proteins (GPCRs). A subgroup of four chemokine receptors known as the atypical chemokine receptors (ACKRs) has emerged as essential regulators of the chemokine functions. ACKRs play diverse and complex roles in tumor biology from tumor initiation to metastasis, including cancer cell proliferation, adherence to endothelium, epithelial-mesenchymal transition (EMT), extravasation from blood vessels, tumor-associated angiogenesis or protection from immunological responses. This chapter gives an overview on the established and emerging roles that the atypical chemokine receptors ACKR1, ACKR2, ACKR3 and ACKR4 play in the different phases of cancer development and dissemination, their clinical relevance, as well as on the hurdles to overcome in ACKRs targeting as cancer therapy.

Effect of functional genetic variants in chemokine decoy receptors on the recurrence risk of breast cancer

Duffy antigen receptor for chemokine (DARC) and CCBP2, the two members of chemokine decoy receptor family, restrain cell proliferation and invasion through sequestrating cytotoxic chemokines. Our previous research clarified two functional nonsynonymous single nucleotide polymorphisms (SNPs): rs12075 in DARC and rs2228468 in CCBP2 were significantly correlated with lymph node metastasis. However, the role of their genetic variations on survival of breast cancer remains unclear. In the present study, rs12075 in DARC and rs2228468 in CCBP2 were genotyped in 806 patients with primary breast cancer. The endpoint was recurrence‐free survival (RFS). Cox regression model was used to explore the association between SNPs and patients’ survival. The results revealed that participants with GG genotype in rs12075 appeared a higher recurrence risk compared with AG/AA genotype after adjustment with clinical parameters including lymph node status (AG+AA vs GG: hazard ratio [HR] = 0.54, 95% confidence interval [CI], 0.31‐0.93, P = 0.027). Furthermore, subgroup analysis revealed that GG genotype frequency of rs12075 had a positive correlation with RFS compared with AG/AA genotype (AG+AA vs GG: HR = 0.22, 95% CI, 0.05‐0.91, P = 0.021) in triple‐negative breast cancer (TNBC) subtype but not in other subtypes. No significant association between the genotypic variants and relapse risk was found in rs2228468 (AC+AA vs CC: HR = 0.80, 95% CI, 0.56‐1.14, P = 0.222). There was also no significant difference in survival among rs2228468 polymorphism in any subtypes. Our study suggested that rs12075 could be served as a key predictive factor of recurrence risk in breast cancer, especially for TNBC subtype. Further researches to monitor SNPs will provide further opportunities to determine clinical prognosis.