VCC-1 over-expression inhibits cisplatin-induced apoptosis in HepG2 cells

Identification of orphan GPR25 as a receptor for the chemokine CXCL17

C-X-C motif chemokine ligand 17 (CXCL17) is a small secretory protein primarily expressed in mucosal tissues, which likely functions as a chemoattractant; however, its receptor is controversial. Herein, we identified the rarely studied orphan G protein-coupled receptor 25 (GPR25) as a receptor of CXCL17 via prediction using the newly developed AlphaFold 3 algorithm and experimental validation. In the NanoLuc Binary Technology (NanoBiT)-based β-arrestin recruitment assay, recombinant human CXCL17 could activate human GPR25 in transfected human embryonic kidney (HEK) 293T cells with an EC50 value around 100 nm, but it had no activation effect on the other 17 tested G protein-coupled receptors. Deletion of three conserved C-terminal residues from human CXCL17 almost abolished its activation effect. Alanine replacement of W95 or R178 of human GPR25, two conserved residues in the predicted orthosteric ligand binding pocket, almost abolished its response to CXCL17. Only the pairing of wild-type CXCL17 with wild-type GPR25 could cause shedding of transforming growth factor α and induce chemotactic movement of transfected HEK293T cells. These results were consistent with the AlphaFold 3-predicted binding model, in which the highly conserved C-terminal fragment of CXCL17 inserts into the orthosteric ligand binding pocket of GPR25. According to their expression pattern shown in the Human Protein Atlas, CXCL17 may be an endogenous agonist of GPR25 in humans and other mammals; however, this hypothesis needs to be tested experimentally in future studies. The present deorphanization paves the way for further functional characterization of the orphan receptor GPR25 and the orphan ligand CXCL17.

Recombinant CXCL17 Treatment Alleviates Hyperoxia-Induced Lung Apoptosis and Inflammation In Vivo and Vitro by Activating the AKT Pathway: A Possible Therapeutic Approach for Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD), caused by hyperoxia exposure, is the most common complication affecting preterm infants. The C-X-C motif chemokine ligand 17 (CXCL17) belongs to the chemokine family that plays important roles in various processes, but the function in BPD is unknown. Elevated serum CXCL17 levels were observed in human premature infants with hyperoxia-induced lung injury, suggesting that CXCL17 might be involved in BPD. To further validate our speculation, studies were conducted in a hyperoxia-induced lung injury mouse model and primary murine alveolar epithelial cells Type II (T2AEC) cells exposed to hyperoxia. RT-qPCR and western blot were used to validate CXCL17 expression in newborn mice. Hyperoxia exposure-induced lung injury was determined by assessing the lung wet-weight/dry-weight ratio and histological changes. Oxidative stress and inflammatory factors were examined by ELISA assay and RT-qPCR. Reactive oxygen species (ROS) level was evaluated by DHE staining. Apoptosis was assessed by TUNEL staining and western blot. The results showed that hyperoxia exposure increased CXCL17 levels in newborn mice pups. Hyperoxia exposure increased lung wet-weight/dry-weight ratio, increased alveolar diameter and enlarged alveoli, and reduced surfactant protein C expression. However, recombinant CXCL17 (rCXCL17) treatment alleviated hyperoxia-induced lung injury. rCXCL17 treatment inhibited hyperoxia-induced inflammation, oxidative stress, and apoptosis in neonatal mice. These results were further verified in T2AEC cells. Additionally, rCXCL17 treatment activated the AKT pathway, which is a protective pathway in BPD. Collectively, rCXCL17 alleviates hyperoxia-induced lung injury in neonatal mice by activating the AKT pathway, indicating that CXCL17 may be a promising target for BPD therapy.

The cryptic role of CXCL17/CXCR8 axis in the pathogenesis of cancers: a review of the latest evidence

Chemokines are immune system mediators that mediate various activities and play a role in the pathogenesis of several cancers. Among these chemokines, C-X-C motif chemokine 17 (CXCL-17) is a relatively novel molecule produced along the airway epithelium in physiological and pathological conditions, and evidence shows that it plays a homeostatic role in most cases. CXCL17 has a protective role in some cancers and a pathological role in others, such as liver and lung cancer. This chemokine, along with its possible receptor termed G protein-coupled receptor 35 (GPR35) or CXCR8, are involved in recruiting myeloid cells, regulating angiogenesis, defending against pathogenic microorganisms, and numerous other mechanisms. Considering the few studies that have been performed on the dual role of CXCL17 in human malignancies, this review has investigated the possible pro-tumor and anti-tumor roles of this chemokine, as well as future treatment options in cancer therapy.

A comprehensive review of chemokine CXC17 (VCC1) in cancer, infection, and inflammation

A crucial component of the immune system are chemokiness. Chemokine's dysregulation has been linked to a number of pathological diseases. Recently, CXCL17, a chemokine belonging to the CXC subfamily, was identified. With regard to a number of physiological conditions and disorders, CXCL17 either has homeostatic or pathogenic effects. Some research suggests that CXCL17 is an orphan ligand, despite the fact that G protein-coupled receptor (GPR) 35 has been suggested as a possible receptor for CXCL17. Since CXCL17 is primarily secreted by mucosal epithelia, such as those in the digestive and respiratory tracts, under physiological circumstances, this chemokine is referred to as a mucosal chemokine. Macrophages and monocytes are the cells that express GPR35 and hence react to CXCL17. In homeostatic conditions, this chemokine has anti-inflammatory, antibacterial, and chemotactic properties. CXCL17 promotes angiogenesis, metastasis, and cell proliferation in pathologic circumstances like malignancies. However, other studies suggest that CXCL17 may have anti-tumor properties. Additionally, studies have shown that CXCL17 may have a role in conditions such as idiopathic pulmonary fibrosis, multiple sclerosis, asthma, and systemic sclerosis. Additionally, deregulation of CXCL17 in some diseases may serve as a biomarker for diagnosis and prognosis. Clarifying the underlying mechanism of CXCL17's activity in homeostatic and pathological situations may thus increase our understanding of its role and hold promise for the development of novel treatment strategies.

Functions of CXC chemokines as biomarkers and potential therapeutic targets in the hepatocellular carcinoma microenvironment

Background

Several studies have indicated that CXC chemokines influence the prognosis and therapy in patients with hepatocellular carcinoma (HCC). However, there are limited studies on the roles of CXC chemokines in HCC based on data acquired from various databases. This study aimed to conduct an in-depth and comprehensive bioinformatic analysis of the expression and functions of CXC chemokines in HCC.

Methods

Data was obtained from various databases including ONCOMINE, UALCAN, STRING, GeneMinia, DAVID, Kaplan-Meier plotter, TIMER, GSCALite and NetworkAnalyst for the analysis of the expression and functions of the CXC chemokines in HCC.

Results

Analysis of the differential expression levels of CXC chemokines between HCC and adjacent normal tissues revealed that the mRNA expression levels of CXCL1/2/5/6/7/12/14 were significantly lower in HCC tissues than those in adjacent normal tissues, whereas the mRNA expression levels of CXCL9/16/17 were significantly higher in HCC tissues. Analysis of the relationship between CXC chemokines and overall survival revealed that high mRNA expression levels of CXCL1/3/5/6/8 were associated with poor overall survival, whereas high mRNA expression levels of CXCL2/4/7/9/10/12 were associated with better overall survival. The functions of CXC chemokines and related genes were associated with cytokine-cytokine receptor interactions and chemokine signaling pathway. Analysis of the association between CXC chemokines and activity of cancer pathways indicated that the DNA damage response and hormone androgen receptor (AR) signaling pathways were inhibited, whereas apoptosis, epithelial-mesenchymal transition (EMT) and Ras/mitogen-activated protein kinase (MAPK) signaling pathways were activated. The expression of CXC chemokines was positively correlated with the infiltration of six types of immune cells (B cells, CD8+ T cells, CD4+ T cells, macrophages, neutrophils and dendritic cells).

Conclusions

This study has demonstrated that CXC chemokines can influence survival of patients with HCC by recruiting different types of immune cells into the tumor microenvironment.

Intestinal guard: Human CXCL17 modulates protective response against mycotoxins and CXCL17-mimetic peptides development

Mycotoxin contamination is an ongoing and growing issue that can create health risks and even cause death. Unfortunately, there is currently a lack of specific therapy against mycotoxins with few side effects. On the other hand, the strategic expression of CXCL17 in mucosal tissues suggests that it may be involved in immune response when exposed to mycotoxins, but the exact role of CXCL17 remains largely unknown. Using Caco-2 as a cell model of the intestinal epithelial barrier (the first line of defense against mycotoxins), we showed that a strong production of ROS-dependent CXCL17 was triggered by mycotoxins via p38 and JNK pathways. Under the mycotoxins stress, CXCL17 modulated enhanced immuno-protective response with a remission of inflammation and apoptosis through PI3K/AKT/mTOR. Based on our observed feedback of CXCL17 to the mycotoxins, we developed the CXCL17-mimetic peptides in silico (CX1 and CX2) that possessed the safety and the capability to ameliorate mycotoxins-inducible inflammation and apoptosis. In this study, the identification of detoxifying feature of CXCL17 is a prominent addition to the chemokine field, pointing out a new direction for curing the mycotoxins-caused damage.

Mucosal chemokine CXCL17: What is known and not known

CXCL17, the last described chemokine, has recently been found to be abundantly and specifically expressed in mucosal sites, while its receptor is still not well determined. Accumulative studies indicate that CXCL17 could potentially exhibit chemotactic, anti-inflammatory, antimicrobial activities under multiple biological conditions. However, the mechanism by which it contributes to the physiological and pathological processes within specific mucosal tissues is still far from being fully elucidated. In this present review, we therefore summarize the current available evidence of CXCL17 with specific emphasis on its biological role and pathophysiological significance, in order to aid in the advancement of CXCL17-related studies.

The protective and pathogenic roles of CXCL17 in human health and disease: Potential in respiratory medicine

•

C-X-C motif chemokine 17 (CXCL17), plays a functional role in maintaining homeostasis at mucosal barriers.

•

CXCL17 expression is associated with both disease progression and protection in various diseases.

•

The multifactorial mechanistic properties of CXCL17 could be exploited as a therapeutic target

C-X-C motif chemokine 17 (CXCL-17) is a novel chemokine that plays a functional role maintaining homeostasis at distinct mucosal barriers, including regulation of myeloid-cell recruitment, angiogenesis, and control of microorganisms. Particularly, CXCL17 is produced along the epithelium of the airways both at steady state and under inflammatory conditions. While increased CXCL17 expression is associated with disease progression in pulmonary fibrosis, asthma, and lung/hepatic cancer, it is thought to play a protective role in pancreatic cancer, autoimmune encephalomyelitis and viral infections. Thus, there is emerging evidence pointing to both a harmful and protective role for CXCL17 in human health and disease, with therapeutic potential for translational applications. In this review, we provide an overview of the discovery, characteristics and functions of CXCL17 emphasizing its clinical potential in respiratory disorders.

CXCL17 promotes cell metastasis and inhibits autophagy via the LKB1-AMPK pathway in hepatocellular carcinoma

As an innovative CXC chemokine, CXCL17 has a mysterious clinical significance and modulating influence on hepatocellular carcinoma (HCC). Our study examined the activity and mechanisms of CXCL17 on growth, autophagy, and metastasis of HCC. Upregulation of CXCL17 expression was observed in HCC, which is correlated with poorer histological stages and outcomes. Elevation of CXCL17 expression promoted proliferation, invasion, and migration and decreased LC-3B biosynthesis and p62 protein reduction, which are known to stimulate autophagy. However, silencing of CXCL17 inhibited the development of these cancerous phenotypes. Furthermore, AMPK was stimulated after knockdown of CXCL17. This stimulation, as well as stimulation of autophagy was caused by liver kinase B1 (LKB1), whose function is induced by knockdown CXCL17. Additionally, knockdown of CXCL17 enhanced nuclear translocation of LKB1. Altogether, these findings suggest that elevated CXCL17 expression in HCC promotes malignant reactions in malignant cells. Our research offers new evidence that chemokine CXCL17 reinforces malignant invasion and suppresses autophagy via the LKB1-AMPK pathway.

The role and clinical significance of the CXCL17-CXCR8 (GPR35) axis in breast cancer

BACKGROUND

Chemokine (C-X-C motif) ligand 17 (CXCL17) is the latest member of the chemokine family. However, its function in various cancer types is unknown. The G protein-coupled receptor 35 (GPR35) was identified as the receptor of CXCL17 and named recently as CXCR8. The function of the CXCL17-CXCR8 (GPR35) biological axis in cancer has not been reported.

METHODS

The expression of CXCL17 and CXCR8 (GPR35) in breast cancer cell lines and a tissue microarray (TMA) was detected through western blot and immunohistochemistry (IHC). Expression data in IHC were analyzed using clinicopatholigical and survival information.

RESULTS

CXCL17 and CXCR8 (GPR35) were found to be variably expressed in breast cancer cell lines. Both expressed higher in breast cancer tissue than normal adjacent tissue. Although CXCL17 can interact with CXCR8 (GPR35) in breast cancer cells in vitro, the expression correlation between these two markers in breast cancer tissue was not found to be significant. As to clinical significance, CXCR8 (GPR35) expression was found to be significantly associated with advanced histological grade and higher proliferation rate indicated by Ki-67 expression. Although CXCL17 was not found to statistically correlate with any clinicopathological characteristics, it was found to be associated with shorter overall survival and is an independent marker of poor prognosis in breast cancer. In addition, CXCL17 was found to promote proliferation and migration of breast cancer cells in vitro and in vivo.

CONCLUSIONS

We investigated the role of the CXCL17-CXCR8 (GPR35) axis in breast cancer for the first time. CXCL17 is a potential oncogene and promising therapeutic target, is an independent biomarker of poor prognosis in patients with breast cancer, and can promote proliferation and migration of breast cancer cells in vitro and in vivo.

CXCL17 expression predicts poor prognosis and correlates with adverse immune infiltration in hepatocellular carcinoma

CXC ligand 17 (CXCL17) is a novel CXC chemokine whose clinical significance remains largely unknown. In the present study, we characterized the prognostic value of CXCL17 in patients with hepatocellular carcinoma (HCC) and evaluated the association of CXCL17 with immune infiltration. We examined CXCL17 expression in 227 HCC tissue specimens by immunohistochemical staining, and correlated CXCL17 expression patterns with clinicopathological features, prognosis, and immune infiltrate density (CD4 T cells, CD8 T cells, B cells, natural killer cells, neutrophils, macrophages). Kaplan-Meier survival analysis showed that both increased intratumoral CXCL17 (P = 0.015 for overall survival [OS], P = 0.003 for recurrence-free survival [RFS]) and peritumoral CXCL17 (P = 0.002 for OS, P<0.001 for RFS) were associated with shorter OS and RFS. Patients in the CXCL17^low group had significantly lower 5-year recurrence rate compared with patients in the CXCL17^high group (peritumoral: 53.1% vs. 77.7%, P<0.001, intratumoral: 58.6% vs. 73.0%, P = 0.001, respectively). Multivariate Cox proportional hazards analysis identified peritumoral CXCL17 as an independent prognostic factor for both OS (hazard ratio [HR] = 2.066, 95% confidence interval [CI] = 1.296–3.292, P = 0.002) and RFS (HR = 1.844, 95% CI = 1.218–2.793, P = 0.004). Moreover, CXCL17 expression was associated with more CD68 and less CD4 cell infiltration (both P<0.05). The combination of CXCL17 density and immune infiltration could be used to further classify patients into subsets with different prognosis for RFS. Our results provide the first evidence that tumor-infiltrating CXCL17⁺ cell density is an independent prognostic factor that predicts both OS and RFS in HCC. CXCL17 production correlated with adverse immune infiltration and might be an important target for anti-HCC therapies.

CXCL17 is a major chemotactic factor for lung macrophages

Chemokines are a superfamily of chemotactic cytokines that direct the movement of cells throughout the body under homeostatic and inflammatory conditions. The mucosal chemokine CXCL17 was the last ligand of this superfamily to be characterized. Several recent studies have provided greater insight into the basic biology of this chemokine and have implicated CXCL17 in several human diseases. We sought to better characterize CXCL17's activity in vivo. To this end, we analyzed its chemoattractant properties in vivo and characterized a Cxcl17 (-/-) mouse. This mouse has a significantly reduced number of macrophages in its lungs compared with wild-type mice. In addition, we observed a concurrent increase in a new population of macrophage-like cells that are F4/80(+)CDllc(mid). These results indicate that CXCL17 is a novel macrophage chemoattractant that operates in mucosal tissues. Given the importance of macrophages in inflammation, these observations strongly suggest that CXCL17 is a major regulator of mucosal inflammatory responses.