Atypical chemokine receptors in tumor cell growth and metastasis

Unraveling the Multifaceted Roles of Atypical Chemokine Receptors in Breast Cancer

Breast cancer (BC) remains one of the most prevalent and deadly malignancies among women globally. A deeper understanding of the molecular mechanisms driving BC progression and metastasis is essential for the development of effective therapeutic strategies. While traditional chemokine receptors are well known for their roles in immune cell migration and positioning, atypical chemokine receptors (ACKRs) have recently gained attention as key modulators in cancer-related processes. Unlike conventional receptors, ACKRs-comprising ACKR1, ACKR2, ACKR3, and ACKR4-primarily function by scavenging chemokines, regulating their availability, and modulating receptor signaling in a ligand-independent manner. This review aims to elucidate the roles of ACKRs in BC, focusing on their influence on the tumor microenvironment (TME), cancer cell proliferation, survival, metastasis, and angiogenesis. Additionally, we will explore the potential of ACKRs as diagnostic and prognostic markers and assess their viability as therapeutic targets. By synthesizing recent research findings and highlighting future research directions, this review seeks to provide a comprehensive understanding of the significance of ACKRs in BC and underscore the need for continued investigation into their therapeutic potential.

Recent advances targeting chemokines for breast cancer

Breast cancer (BC) is a complex and heterogeneous disease, and its onset and progression involve the interplay of multiple molecular mechanisms. Chemokines and their receptors are key regulators of cell migration and immune responses and contribute significantly to the pathophysiology of BC. This article reviews the classification, functions, and mechanisms of chemokines and their receptors in the proliferation, migration, invasion, and angiogenesis of BC cells. This study explores the regulatory roles of chemokines and their receptors in the immune microenvironment of BC, particularly the ways they influence the infiltration, polarization, and antitumor immune responses of immune cells. Finally, this article summarizes the current treatment strategies for breast cancer that utilize chemokines and their receptors and provides insights into future research directions and trends in this field.

Prenatal Programming of Monocyte Chemotactic Protein-1 Signaling in Autism Susceptibility

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder that involves functional and structural defects in selective central nervous system (CNS) regions, harming the individual capability to process and respond to external stimuli, including impaired verbal and non-verbal communications. Etiological causes of ASD have not been fully clarified; however, prenatal activation of the innate immune system by external stimuli might infiltrate peripheral immune cells into the fetal CNS and activate cytokine secretion by microglia and astrocytes. For instance, genomic and postmortem histological analysis has identified proinflammatory gene signatures, microglia-related expressed genes, and neuroinflammatory markers in the brain during ASD diagnosis. Active neuroinflammation might also occur during the developmental stage, promoting the establishment of a defective brain connectome and increasing susceptibility to ASD after birth. While still under investigation, we tested the hypothesis whether the monocyte chemoattractant protein-1 (MCP-1) signaling is prenatally programmed to favor peripheral immune cell infiltration and activate microglia into the fetal CNS, setting susceptibility to autism-like behavior. In this review, we will comprehensively provide the current understanding of the prenatal activation of MCP-1 signaling by external stimuli during the developmental stage as a new selective node to promote neuroinflammation, brain structural alterations, and behavioral defects associated to ASD diagnosis.

LRRC8A as a central mediator promotes colon cancer metastasis by regulating PIP5K1B/PIP2 pathway

Colorectal cancer (CRC) has been the third most common malignancy and the second cause of cancer-related mortality. As the core of volume-sensitive chloride currents, leucine-rich repeat-containing 8A (LRRC8A) contributes to tumor progression but is not consistent, especially for whom the roles in colon carcinoma metastasis were not fully elucidated. Herein, LRRC8A proteins were found highly expressed in hematogenous metastasis from human colorectal cancer samples. The oxaliplatin-resistant HCT116 cells highly expressed LRRC8A, which was related to impaired proliferation and enhanced migration. The over-expressed LRRC8A slowed proliferation and increased migration ex vivo and in vivo. The elevated LRRC8A upregulated the focal adhesion, MAPK, AMPK, and chemokine signaling pathways via phosphorylation and dephosphorylation. Inhibition of LRRC8A impeded the TNF-α signaling cascade and TNF-α-induced migration. LRRC8A binding to PIP5K1B regulated the PIP2 formation, providing a platform for LRRC8A to mediate cell signaling transduction. Importantly, LRRC8A self-regulated its transcription via NF-κB1 and NF-κB2 pathways and the upregulation of NIK/NF-κB2/LRRC8A transcriptional axis was unfavorable for colon cancer patients. Collectively, our findings reveal that LRRC8A is a central mediator in mediating multiple signaling pathways to promote metastasis and targeting LRRC8A proteins could become a potential clinical biomarker-driven treatment strategy for colon cancer patients.

Exploring the tumor microenvironment: Chemokine-related genes and immunotherapy/chemotherapy response in clear-cell renal cell carcinoma

BACKGROUND

The treatment of clear-cell renal cell carcinoma (ccRCC) remains challenge. Chemokines laid impact on the proliferation and metastasis of cancer cells. The objective was to identify the chemokine-related genes and construct a prognostic model for ccRCC.

METHODS

Bulk transcriptomic data (n = 531), single-cell RNA sequencing (scRNA-seq) dataset GSE159115, and other validation cohorts were acquired from the Cancer Genome Atlas Program (TCGA) and GEO databases. All clustering analysis was conducted by Seurat R package. Gene set enrichment analysis (GSEA), immune infiltration analysis, single nucleotide variations (SNV) analysis, and predictive response analysis of immunotherapy/chemotherapy were conducted. 786-O and A498 cell lines were cultured and applied into CCK-8, Western blot, and RT-qPCR kits.

RESULTS

Univariate Cox analysis was used to screen out chemokine-related genes related to survival. ZIC2, SMIM24, COL7A1, IGF2BP3, ITPKA, ADAMTS14, CYP3A7, and AURKB were identified and applied for the construction of the prognostic model. High-risk group had a poorer prognosis than the low-risk group in each dataset. Memory CD8+ T cells, macrophages, and memory B cells were higher in the high-risk group, while the content of basophils was higher in the low-risk group. Bortezomib_1191, Dactinomycin_1911, Docetaxel_1007, and Daporinad_1248 were more sensitive to high-risk groups than low-risk groups. Moreover, we found that IGF2BP3 significantly elevated in both 786-O and A498 cell lines resistance to sunitinib. Knockdown of IGF2BP3 markedly reduced ccRCC cell migration and viability.

CONCLUSION

Our study has yielded a novel prognostic model of chemokine-related genes based on comprehensive transcriptional atlas of ccRCC patients, shedding light on the significant impact of the tumor microenvironment on biology and immunotherapy response of ccRCC. We identified IGF2BP3 as a pivotal regulator in regulating ccRCC resistance to sunitinib.

Non-canonical G protein signaling

The original paradigm of classical - also referred to as canonical - cellular signal transduction of heterotrimeric G proteins (G protein) is defined by a hierarchical, orthograde interaction of three players: the agonist-activated G protein-coupled receptor (GPCR), which activates the transducing G protein, that in turn regulates its intracellular effectors. This receptor-transducer-effector concept was extended by the identification of regulators and adapters such as the regulators of G protein signaling (RGS), receptor kinases like βARK, or GPCR-interacting arrestin adapters that are integrated into this canonical signaling process at different levels to enable fine-tuning. Finally, the identification of atypical signaling mechanisms of classical regulators, together with the discovery of novel modulators, added a new and fascinating dimension to the cellular G protein signal transduction. This heterogeneous group of accessory G protein modulators was coined "activators of G protein signaling" (AGS) proteins and plays distinct roles in canonical and non-canonical G protein signaling pathways. AGS proteins contribute to the control of essential cellular functions such as cell development and division, intracellular transport processes, secretion, autophagy or cell movements. As such, they are involved in numerous biological processes that are crucial for diseases, like diabetes mellitus, cancer, and stroke, which represent major health burdens. Although the identification of a large number of non-canonical G protein signaling pathways has broadened the spectrum of this cellular communication system, their underlying mechanisms, functions, and biological effects are poorly understood. In this review, we highlight and discuss atypical G protein-dependent signaling mechanisms with a focus on inhibitory G proteins (Gi) involved in canonical and non-canonical signal transduction, review recent developments and open questions, address the potential of new approaches for targeted pharmacological interventions.

The origin, evolution, and molecular diversity of the chemokine system

Chemokine signalling performs key functions in cell migration via chemoattraction, such as attracting leukocytes to the site of infection during host defence. The system consists of a ligand, the chemokine, usually secreted outside the cell, and a chemokine receptor on the surface of a target cell that recognises the ligand. Several noncanonical components interact with the system. These include a variety of molecules that usually share some degree of sequence similarity with canonical components and, in some cases, are known to bind to canonical components and/or to modulate cell migration. Whereas canonical components have been described in vertebrate lineages, the distribution of the noncanonical components is less clear. Uncertainty over the relationships between canonical and noncanonical components hampers our understanding of the evolution of the system. We used phylogenetic methods, including gene-tree to species-tree reconciliation, to untangle the relationships between canonical and noncanonical components, identify gene duplication events, and clarify the origin of the system. We found that unrelated ligand groups independently evolved chemokine-like functions. We found noncanonical ligands outside vertebrates, such as TAFA "chemokines" found in urochordates. In contrast, all receptor groups are vertebrate-specific and all-except ACKR1-originated from a common ancestor in early vertebrates. Both ligand and receptor copy numbers expanded through gene duplication events at the base of jawed vertebrates, with subsequent waves of innovation occurring in bony fish and mammals.

CC chemokine receptors are prognostic indicators of gastric cancer and are associated with immune infiltration

BACKGROUND

CC chemokine receptors are responsible for regulating the tumor microenvironment (TME) and participating in carcinogenesis and tumor advancement. However, no functional study has investigated CC chemokine receptors in gastric cancer (GC) prognosis, risk, immunotherapy, or other treatments.

METHODS

We conducted a bioinformatics analysis on GC data using online databases, including the Human Protein Atlas (HPA), Kaplan-Meier (KM) plotter, GeneMANIA, MethSurv, the University of ALabama at Birmingham CANcer (UALCAN) Data Analysis Portal, Gene Set Cancer Analysis (GSCA), cBioportal, and Tumor IMmune Estimation Resource (TIMER).

RESULTS

We noted that CC chemokine receptor expression correlated with survival in GC. CC chemokine receptor expression was also strongly linked to different tumor-infiltrating immune cells. Additionally, CC chemokine receptors were found to be broadly drug-resistant in GC.

CONCLUSION

Our study identifed CC chemokine receptor expression helped in predicting the prognosis of patients diagnosed with GC. The expression level of the CC chemokine receptors was also positively related to multiple tumor-infiltrating lymphocytes (TILs). These findings provide evidence to monitor patients with GC using CC chemokine receptors, which can be used as an effective biomarker for predicting the disease prognosis and be regarded as a therapeutic target for modulating the tumor immune microenvironment.

Comprehensive analysis of ACKR family members in breast cancer using prognostic values

Breast cancer (BC) is by far the most prevalent malignancy found in the female population. Atypical chemokine receptors (ACKRs) are a subclass of G-protein-coupled receptors, which are characterized by disrupted ligand binding and a breakdown of signaling following ligand binding. The evolution and function of multiple ACKRs in BC have yet to be fully elucidated, although certain findings on this family have been reported in several studies in Homo sapiens and other species. The present study identified that the expression level of ACKRs was significantly lower in breast carcinoma (BRCA) tissues compared with normal breast tissues through searches of the Tumor Immune Estimation Resource, UALCAN and Gene Expression Profiling Interactive Analysis databases. Additionally, when comparing BRCA tissues with normal breast tissues, it was found that there was obvious hypomethylation in the promoters of ACKR1, ACKR3 and ACKR5, as well as a marked hypermethylation in the promoters of ACKR2 and ACKR6. In determining the prognosis of patients with BRCA, the expression levels of ACKR1, ACKR2, ACKR3, ACKR4 and ACKR6 were all found to be important factors. The values for distant metastasis-free survival (DMFS), overall survival (OS) and recurrence-free survival (RFS) were all found to be lower in patients with BRCA who had a low expression level of ACKR1. In addition, the RFS rates for patients with BRCA were lower when the expression of ACKR2 was low, and worse values for DMFS, OS and RFS were found to be highly correlated with higher expression levels of ACKR3. Moreover, the DMFS, OS, RFS and predictive power score values were worse in those patients with low ACKR4 expression, and the RFS values for patients with BRCA were also found to be lower when the expression level of ACKR6 was low. Additionally, dendritic cells, macrophages, neutrophils, T cells with CD4+ status, T cells with CD8+ status and B cells were all substantially linked with ACKR expression, as well as immune cell infiltration. Taken together, the findings of the present study may offer a theoretical foundation for the creation of novel targets and prognostic indicators for BRCA therapy.

β-Arrestins: Structure, Function, Physiology, and Pharmacological Perspectives

The two β-arrestins, β-arrestin-1 and -2 (systematic names: arrestin-2 and -3, respectively), are multifunctional intracellular proteins that regulate the activity of a very large number of cellular signaling pathways and physiologic functions. The two proteins were discovered for their ability to disrupt signaling via G protein-coupled receptors (GPCRs) via binding to the activated receptors. However, it is now well recognized that both β-arrestins can also act as direct modulators of numerous cellular processes via either GPCR-dependent or -independent mechanisms. Recent structural, biophysical, and biochemical studies have provided novel insights into how β-arrestins bind to activated GPCRs and downstream effector proteins. Studies with β-arrestin mutant mice have identified numerous physiologic and pathophysiological processes regulated by β-arrestin-1 and/or -2. Following a short summary of recent structural studies, this review primarily focuses on β-arrestin-regulated physiologic functions, with particular focus on the central nervous system and the roles of β-arrestins in carcinogenesis and key metabolic processes including the maintenance of glucose and energy homeostasis. This review also highlights potential therapeutic implications of these studies and discusses strategies that could prove useful for targeting specific β-arrestin-regulated signaling pathways for therapeutic purposes. SIGNIFICANCE STATEMENT: The two β-arrestins, structurally closely related intracellular proteins that are evolutionarily highly conserved, have emerged as multifunctional proteins able to regulate a vast array of cellular and physiological functions. The outcome of studies with β-arrestin mutant mice and cultured cells, complemented by novel insights into β-arrestin structure and function, should pave the way for the development of novel classes of therapeutically useful drugs capable of regulating specific β-arrestin functions.

Chemokine receptor CXCR7 activates Aurora Kinase A and promotes neuroendocrine prostate cancer growth

CXCR7 is an atypical chemokine receptor that recruits β-arrestin (ARRB2) and internalizes into clathrin-coated intracellular vesicles where the complex acts as a scaffold for cytoplasmic kinase assembly and signal transduction. Here, we report that CXCR7 was elevated in the majority of prostate cancer (PCa) cases with neuroendocrine features (NEPC). CXCR7 markedly induced mitotic spindle and cell cycle gene expression. Mechanistically, we identified Aurora Kinase A (AURKA), a key regulator of mitosis, as a novel target that was bound and activated by the CXCR7-ARRB2 complex. CXCR7 interacted with proteins associated with microtubules and golgi, and, as such, the CXCR7-ARRB2-containing vesicles trafficked along the microtubules to the pericentrosomal golgi apparatus, where the complex interacted with AURKA. Accordingly, CXCR7 promoted PCa cell proliferation and tumor growth, which was mitigated by AURKA inhibition. In summary, our study reveals a critical role of CXCR7-ARRB2 in interacting and activating AURKA, which can be targeted by AURKA inhibitors to benefit a subset of patients with NEPC.

Unraveling the Role of Adiponectin Receptors in Obesity-Related Breast Cancer

Obesity has a noteworthy role in breast tumor initiation and progression. Among the mechanisms proposed, the most validated is the development of chronic low-grade inflammation, supported by immune cell infiltration along with dysfunction in adipose tissue biology, characterized by an imbalance in adipocytokines secretion and alteration of their receptors within the tumor microenvironment. Many of these receptors belong to the seven-transmembrane receptor family, which are involved in physiological features, such as immune responses and metabolism, as well as in the development and progression of several malignancies, including breast cancer. These receptors are classified as canonical (G protein-coupled receptors, GPCRs) and atypical receptors, which fail to interact and activate G proteins. Among the atypical receptors, adiponectin receptors (AdipoRs) mediate the effect of adiponectin, the most abundant adipocytes-derived hormone, on breast cancer cell proliferation, whose serum levels are reduced in obesity. The adiponectin/AdipoRs axis is becoming increasingly important regarding its role in breast tumorigenesis and as a therapeutic target for breast cancer treatment. The objectives of this review are as follows: to point out the structural and functional differences between GPCRs and AdipoRs, and to focus on the effect of AdipoRs activation in the development and progression of obesity-dependent breast cancer.

Peptide Drug Conjugates and Their Role in Cancer Therapy

Drug conjugates have become a significant focus of research in the field of targeted medicine for cancer treatments. Peptide-drug conjugates (PDCs), a subset of drug conjugates, are composed of carrier peptides ranging from 5 to 30 amino acid residues, toxic payloads, and linkers that connect the payload to the peptide. PDCs are further broken down into cell-penetrating peptides (CPPs) and cell-targeting peptides (CTPs), each having their own differences in the delivery of cytotoxic payloads. Generally, PDCs as compared to other drug conjugates-like antibody-drug conjugates (ADCs)-have advantages in tumor penetration, ease of synthesis and cost, and reduced off-target effects. Further, as compared to traditional cancer treatments (e.g., chemotherapy and radiation), PDCs have higher specificity for the target cancer with generally less toxic side effects in smaller doses. However, PDCs can have disadvantages such as poor stability and rapid renal clearance due to their smaller size and limited oral bioavailability due to digestion of its peptide structure. Some of these challenges can be overcome with modifications, and despite drawbacks, the intrinsic small size of PDCs with high target specificity still makes them an attractive area of research for cancer treatments.

Atypical chemokine receptors: emerging therapeutic targets in cancer

Atypical chemokine receptors (ACKRs) regulate the availability of chemokines via chemokine scavenging, while also having the capacity to elicit downstream function through β-arrestin coupling. This contrasts with conventional chemokine receptors that directly elicit immune cell migration through G protein-coupled signaling. The significance of ACKRs in cancer biology has previously been poorly understood, but recent findings have highlighted the multifaceted role of these receptors in tumorigenesis and immune response modulation within the tumor microenvironment (TME). Additionally, recent research has expanded our understanding of the function of several receptors including GPR182, CCRL2, GPR1, PITPNM3, and C5aR2 that share similarities with the ACKR family. In this review, we discuss these recent developments, and highlight the opportunities and challenges of pharmacologically targeting ACKRs in cancer.

Identification of Immune Subtypes of Esophageal Adenocarcinoma to Predict Prognosis and Immunotherapy Response

A low response rate limits the application of immune checkpoint inhibitors (ICIs) in the treatment of esophageal adenocarcinoma (EAC), which requires the precise characterization of heterogeneous tumor microenvironments. This study aimed to identify the molecular features and tumor microenvironment compositions of EAC to facilitate patient stratification and provide novel strategies to improve clinical outcomes. Here, we performed consensus molecular subtyping with nonnegative matrix factorization (NMF) using EAC data from the Cancer Genome Atlas (TCGA) and identified two distinct subtypes with significant prognostic differences and differences in tumor microenvironments. The findings were further validated in independent EAC cohorts and potential response to ICI therapy was estimated using Tumor Immune Dysfunction and Exclusion (TIDE) and SubMap methods. Our findings suggest that EAC patients of subtype 2 with low levels of cancer-associated fibroblasts, tumor associated macrophages (TAMs), and MDSCs in the tumor microenvironment may benefit from PD-1 blockade therapy, while patients of subtype 1 are more responsive to chemotherapy or combination therapy. These findings might improve our understanding of immunotherapy efficacy and be useful in the development of new strategies to better guide immunotherapy and targeted therapy in the treatment of EAC.

Single-cell RNA sequencing reveals the multi-cellular ecosystem in different radiological components of pulmonary part-solid nodules

BACKGROUND

Early-stage lung adenocarcinoma that radiologically manifests as part-solid nodules, consisting of both ground-glass and solid components, has distinctive growth patterns and prognosis. The characteristics of the tumour microenvironment and transcriptional features of the malignant cells of different radiological phenotypes remain poorly understood.

METHODS

Twelve treatment-naive patients with radiological part-solid nodules were enrolled. After frozen pathology was confirmed as lung adenocarcinoma, two regions (ground-glass and solid) from each of the 12 part-solid nodules and 5 normal lung tissues from 5 of the12 patients were subjected to single-cell sequencing by 10x Genomics. We used Seurat v3.1.5 for data integration and analysis.

RESULTS

We comprehensively dissected the multicellular ecosystem of the ground-glass and solid components of part-solid nodules at the single-cell resolution. In tumours, these components had comparable proportions of malignant cells. However, the angiogenesis, epithelial-to-mesenchymal transition, KRAS, p53, and cell-cycle signalling pathways were significantly up-regulated in malignant cells within solid components compared to those within ground-glass components. For the tumour microenvironment, the relative abundance of myeloid and NK cells tended to be higher in solid components than in ground-glass components. Slight subtype composition differences existed between the ground-glass and solid components. The T/NK cell subsets' cytotoxic function and the macrophages' pro-inflammation function were suppressed in solid components. Moreover, pericytes in solid components had a stronger communication related to angiogenesis promotion with endothelial cells and tumour cells.

CONCLUSION

The cellular landscape of ground-glass components is significantly different from that of normal tissue and similar to that of solid components. However, transcriptional differences exist in the vital signalling pathways of malignant and immune cells within these components.

Role of the CCL2-CCR2 signalling axis in cancer: Mechanisms and therapeutic targeting

The chemokine ligand CCL2 and its receptor CCR2 are implicated in the initiation and progression of various cancers. CCL2 can activate tumour cell growth and proliferation through a variety of mechanisms. By interacting with CCR2, CCL2 promotes cancer cell migration and recruits immunosuppressive cells to the tumour microenvironment, favouring cancer development. Over the last several decades, a series of studies have been conducted to explore the CCL2-CCR2 signalling axis function in malignancies. Therapeutic strategies targeting the CCL2- CCR2 axis have also shown promising effects, enriching our approaches for fighting against cancer. In this review, we summarize the role of the CCL2-CCR2 signalling axis in tumorigenesis and highlight recent studies on CCL2-CCR2 targeted therapy, focusing on preclinical studies and clinical trials.

G-protein-coupled receptors as therapeutic targets for glioblastoma

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumour in adults. Treatments include surgical resection, radiotherapy, and chemotherapy. Despite this, the prognosis remains poor, with an impacted quality of life during treatment coupled with brain tumour recurrence; thus, new treatments are desperately needed. In this review, we focus on recent advances in G-protein-coupled receptor (GPCR) targets. To date, the most promising targets are the chemokine, cannabinoid, and dopamine receptors, but future work should further examine the melanocortin receptor-4 (MC4R), adhesion, lysophosphatidic acid (LPA) and smoothened (Smo) receptors to initiate new drug-screening strategies and targeted delivery of safe and effective GBM therapies.

Chemokines orchestrate tumor cells and the microenvironment to achieve metastatic heterogeneity

Chemokines, a subfamily of the cell cytokines, are low molecular weight proteins known to induce chemotaxis in leukocytes in response to inflammatory and pathogenic signals. A plethora of literature demonstrates that chemokines and their receptors regulate tumor progression and metastasis. With these diverse functionalities, chemokines act as a fundamental link between the tumor cells and their microenvironment. Recent studies demonstrate that the biology of chemokines and their receptor in metastasis is complex as numerous chemokines are involved in regulating site-specific tumor growth and metastasis. Successful treatment of disseminated cancer is a significant challenge. The most crucial problem for treating metastatic cancer is developing therapy regimes capable of overcoming heterogeneity problems within primary tumors and among metastases and within metastases (intralesional). This heterogeneity of malignant tumor cells can be related to metastatic potential, response to chemotherapy or specific immunotherapy, and many other factors. In this review, we have emphasized the role of chemokines in the process of metastasis and metastatic heterogeneity. Individual chemokines may not express the full potential to address metastatic heterogeneity, but chemokine networks need exploration. Understanding the interplay between chemokine-chemokine receptor networks between the tumor cells and their microenvironment is a novel approach to overcome the problem of metastatic heterogeneity. Recent advances in the understanding of chemokine networks pave the way for developing a potential targeted therapeutic strategy to treat metastatic cancer.

Tumor-associated macrophages-mediated CXCL8 infiltration enhances breast cancer metastasis: Suppression by Danirixin

Breast cancer is the most frequent cancer among females and the second most common cause of cancer deaths worldwide. Tumor-associated macrophages (TAMs) are the most abundant immune cell population in the tumor microenvironment, including breast cancer. Breast cancer stem cells (BCSCs) play an important role in regulating breast cancer growth and metastasis, which still remains an obstacle for successful treatment of breast cancer and requires further investigation, as well as the potential therapeutic strategies. Cytokine array validated that C-X-C motif chemokine ligand 8 (CXCL8) is a pivotal chemokine secreted by TAMs, and CXCL8 could enhance breast cancer migration, invasion ability, and epithelial-mesenchymal transition (EMT) in both animal and human breast cancer. In this study, the clinical data firstly indicated that high CXCL8 expression was significantly associated with metastasis and tumor growth in breast cancer patients. Then, we showed that TAMs-released CXCL8 could markedly elevate the migration, invasion and EMT events in breast cancer cells, as well as the self-renewal of BCSCs in vitro. These processes were markedly abrogated by the treatment of Danirixin, a reversible and selective antagonist of CXC chemokine receptor 2 (CXCR2). Consistently, the in vivo analysis confirmed that CXCL8 suppression using Danirixin effectively reduced the tumor growth, lung metastasis and repressed the self-renewal of BCSCs. Collectively, TAMs/CXCL8 could enhance BCSCs self-renewal and breast cancer metastasis, and these effects could be markedly abolished by Danirixin treatment, suppressing breast cancer progression consequently. Therefore, Danirixin could be considered as a novel and effective therapeutic strategy for breast cancer treatment without obvious toxicity to major organs.

CC Chemokine Receptors in Lung Adenocarcinoma: The Inflammation-Related Prognostic Biomarkers and Immunotherapeutic Targets

Background

Lung adenocarcinoma (LUAD) is the most common type of lung cancer with a high incidence and increased mortality. CC chemokine receptors were participating in the modulation of the tumor microenvironment and involved in carcinogenesis and tumor development. However, the potential mechanistic values of CC chemokine receptors as clinical biomarkers and therapeutic targets in LUAD have not been fully clarified.

Methodology

ONCOMINE, UALCAN, GEPIA, Kaplan-Meier Plotter, SurvExpress, MethSurv, SurvivalMeth, cBioPortal, String, GeneMANIA, DAVID, Metascape, TRRUST, LinkedOmics, and Timer were applied in this work.

Results

The transcriptional levels of CCR1/10 in LUAD tissues were significantly reduced while the transcriptional levels of CCR3/6/7/8 were significantly elevated, and the expression of CCR1 was the highest in LUAD among these CC chemokine receptors. A significant correlation was found between the expression of CCR2/4/6/7 and the pathological stage of LUAD patients. There were significant associations between CCR2/3/4/5/6/10 expression levels and OS in LUAD, and LUAD patients with high transcriptional levels of CCR3/4 had inferior first-progression survival. In addition, the prognostic values of CC chemokine receptors signature in LUAD were explored in three independent cohorts, the high-risk group displayed unfavorable OS compared with the low-risk group, and the LUAD cases in the high-risk group also suffered inferior RFS than that in the low-risk group. And for the prognostic value of the DNA methylation of CC chemokine receptors, we found 1 CpG of CCR2, 2 CpGs of CCR3, 1 CpG of CCR4, 3 CpGs of CCR6, 3 CpGs of CCR7, 1 CpG of CCR8, and 3 CpGs of CCR9 were significantly associated with prognosis in LUAD patients. However, the DNA methylation signature analysis showed there was no statistically significant association between the high- and low-risk group. For potential mechanism, the neighbor gene networks, interaction analyses, functional enrichment analyses of CC chemokine receptors in LUAD were performed, the transcription factor targets, kinase targets, and miRNA targets of CC chemokine receptors were also identified in LUAD. We also found significant correlations among CC chemokine receptors expression and the infiltration of immune cells, the tumor infiltration levels among LUAD with different somatic copy number alterations of these chemokine receptors were also assessed. Moreover, the Cox proportional hazard model showed that CCR1/2/10, B_cell, CD4_Tcell were significantly related to the clinical outcome of LUAD patients.

Conclusion

CC chemokine receptors might serve as immunotherapeutic targets and prognostic biomarkers in LUAD.