The Clinical Significance and Role of CXCL1 Chemokine in Gastrointestinal Cancers

One area of cancer research is the interaction between cancer cells and immune cells, in which chemokines play a vital role. Despite this, a comprehensive summary of the involvement of C-X-C motif ligand 1 (CXCL1) chemokine (also known as growth-regulated gene-α (GRO-α), melanoma growth-stimulatory activity (MGSA)) in cancer processes is lacking. To address this gap, this review provides a detailed analysis of CXCL1's role in gastrointestinal cancers, including head and neck cancer, esophageal cancer, gastric cancer, liver cancer (hepatocellular carcinoma (HCC)), cholangiocarcinoma, pancreatic cancer (pancreatic ductal adenocarcinoma), and colorectal cancer (colon cancer and rectal cancer). This paper presents the impact of CXCL1 on various molecular cancer processes, such as cancer cell proliferation, migration, and invasion, lymph node metastasis, angiogenesis, recruitment to the tumor microenvironment, and its effect on immune system cells, such as tumor-associated neutrophils (TAN), regulatory T (T_reg) cells, myeloid-derived suppressor cells (MDSCs), and macrophages. Furthermore, this review discusses the association of CXCL1 with clinical aspects of gastrointestinal cancers, including its correlation with tumor size, cancer grade, tumor-node-metastasis (TNM) stage, and patient prognosis. This paper concludes by exploring CXCL1's potential as a therapeutic target in anticancer therapy.

CXCL1 confers a survival advantage in Kaposi's sarcoma-associated herpesvirus-infected human endothelial cells through STAT3 phosphorylation

Many cytokines produced by Kaposi's sarcoma-associated herpesvirus (KSHV)-infected cells have been shown to participate in the pathogenesis of KSHV. Determination of the exact role of cytokines in Kaposi's sarcoma (KS) pathogenesis is limited, however, by the difficulty to manipulate the target genes in human endothelial cells. In this study, we sought to elucidate the role of cytokines in KSHV-infected human immortalized endothelial cell line (HuARLT cells) by knockout (KO) of the corresponding target genes using the CRISPR/Cas9 system. The cytokine production profile of KSHV-infected HuARLT cells was analyzed using a protein array, and several cytokines were found to be highly upregulated following KSHV infection. This study focused on CXCL1, which was investigated by knocked out in HuARLT cells. KSHV-infected CXCL1 KO cells underwent increased cell death compared to KSHV-infected wild-type (WT) cells and mock-infected CXCL1 KO cells. Lytic replication was not observed in KSHV-infected WT nor CXCL1 KO cells. Phosphorylation of STAT3 was significantly suppressed in KSHV-infected CXCL1 KO cells. Additionally, inhibitors of STAT3 and CXCL1 induced cell death in KSHV-infected endothelial cells. Our results show that CXCL1 production is required for the survival of KSHV-infected endothelial cells, and the CXCL1 to STAT3 phosphorylation signaling pathway may be a therapeutic target for KS.

CXCR2 Receptor: Regulation of Expression, Signal Transduction, and Involvement in Cancer

Chemokines are a group of about 50 chemotactic cytokines crucial for the migration of immune system cells and tumor cells, as well as for metastasis. One of the 20 chemokine receptors identified to date is CXCR2, a G-protein-coupled receptor (GPCR) whose most known ligands are CXCL8 (IL-8) and CXCL1 (GRO-α). In this article we present a comprehensive review of literature concerning the role of CXCR2 in cancer. We start with regulation of its expression at the transcriptional level and how this regulation involves microRNAs. We show the mechanism of CXCR2 signal transduction, in particular the action of heterotrimeric G proteins, phosphorylation, internalization, intracellular trafficking, sequestration, recycling, and degradation of CXCR2. We discuss in detail the mechanism of the effects of activated CXCR2 on the actin cytoskeleton. Finally, we describe the involvement of CXCR2 in cancer. We focused on the importance of CXCR2 in tumor processes such as proliferation, migration, and invasion of tumor cells as well as the effects of CXCR2 activation on angiogenesis, lymphangiogenesis, and cellular senescence. We also discuss the importance of CXCR2 in cell recruitment to the tumor niche including tumor-associated neutrophils (TAN), tumor-associated macrophages (TAM), myeloid-derived suppressor cells (MDSC), and regulatory T (T_reg) cells.

Sequential Expression of Chemokines in Chronic Subdural Hematoma Fluids after Trepanation Surgery

Chronic subdural hematoma (CSDH) is considered an angiogenic and inflammatory disease. Chemokines attract leukocytes, and invading neutrophils and monocytes/macrophages play important roles in wound healing. However, no studies have been reported regarding changes in expression of chemokines in CSDH fluid after trepanation surgery. We randomly divided patients who underwent trepanation surgery into two groups. One was the irrigation group, in which irrigation of CSDH fluids was performed and a drainage tube was placed (n = 10). The other was the non-irrigation group, in which a drainage tube was inserted without irrigation (n = 10). CSDH fluids were collected during the trepanation surgery, immediately after surgery and on day 1 through the drainage tube. The concentrations of interleukin-8 (IL-8), growth-regulated oncogene-α (GRO-α), epithelial neutrophil-activating peptide 78 (ENA-78), monocyte chemoattractant protein-1 (MCP-1), interferon-γ-induced protein-10 (IP-10), tissue plasminogen activator (tPA), von Willebrand factor (vWF), eotaxin-3, and myeloperoxidase (MPO) in each CSDH fluid sample were measured using enzyme-linked immunosorbent assay kits. After irrigation, concentrations of all chemokines decreased. However, concentrations of IL-8, GRO-α, ENA-78, MCP-1, and MPO were significantly increased on day 1 compared with concentrations during surgery with or without irrigation. In contrast, there were no changes in concentrations of IP-10, eotaxin-3, tPA, or vWF after trepanation surgery. Moreover, there were significant relationships among concentrations of IL-8, GRO-α, ENA-78, and MCP-1 during the surgery and on day 1. In CSDH fluids, chemokines that attract neutrophils, such as IL-8, GRO-α, ENA-78, and macrophage-attracting MCP-1, appear first after trepanation surgery, whereas lymphocyte-attracting IP-10 and eosinophil-attracting eotaxin-3 levels do not change within 1 day of surgery. These findings suggest that neutrophils and macrophages may play important roles in the healing process of CSDH at an early stage.

Epithelial-mesenchymal transition induced by GRO-α-CXCR2 promotes bladder cancer recurrence after intravesical chemotherapy

Non-muscle invasive bladder cancers (NMIBC) are typically treated by transurethral resection with intravesical chemotherapy. However, the post-therapeutic incidence of tumor recurrence and progression to muscle invasive disease is high, and the underlying mechanism(s) remains unknown. In this study, we observed that recurrent bladder cancer cells exhibit a mesenchymal phenotype, which is initiated by the autocrine GRO-α signaling. Mechanically, the chemotherapeutic drug epidoxorubicin induces GRO-α expression in primary bladder cancer cells at G1/S phase via p38-dependent activation of NF-κB. GRO-α phosphorylation of Snail on Ser246 supports Snail's accumulation in the nucleus, and thereby promotes transcription repression activity of Snail from E-cadherin promoters. In accordance, disrupting the GRO-α-Snail axis in NMIBC represents a promising alternative to prevent post-therapeutic tumor progression and recurrence.

GRO-α and IL-8 enhance ovarian cancer metastatic potential via the CXCR2-mediated TAK1/NFκB signaling cascade

Intraperitoneal metastasis is a common occurrence and is usually involved in the poor prognosis of ovarian cancer. Its specific metastatic pattern implies that certain indispensable microenvironmental factors secreted in the peritoneal cavity can direct metastatic ovarian cancer cells to permissive niches for secondary lesion formation. However, the underlying molecular mechanisms are ill defined. Herein, we report that GRO-α and IL-8 are predominately upregulated in culture media derived from either normal or cancerous omenta and are associated with increased ovarian cancer aggressiveness. Methods: OCM was established from culture medium of fresh human omental tissues. Primary and metastatic ovarian cancer cell lines were generated from human tumor tissues and verified by specific antibodies. The functional roles of GRO-α, IL-8, and their specific receptor CXCR2 were examined by neutralizing antibodies, shRNA gene knockdown, CRISPR/Cas9 gene knockout and pharmaceutical CXCR2 inhibitor SB225002. The oncogenic properties of ovarian cancer cells were examined by in vitro and in vivo mouse models. Results: Both GRO-α and IL-8 can activate TAK1/NFκB signaling via the CXCR2 receptor. Intriguingly, TAK1/NFκB signaling activity was higher in metastatic ovarian cancer cells; this higher activity makes them more susceptible to OCM-induced tumor aggressiveness. Treatment of ovarian cancer cells with GRO-α and IL-8 neutralizing antibodies or ablation of CXCR2 by shRNA gene knockdown, CRISPR/Cas9 gene knockout, or CXCR2 inhibitor SB225002 treatment significantly attenuated TAK1/NFκB signaling and decreased in vitro and in vivo oncogenic and metastatic potential, suggesting CXCR2 plays a key role in the GRO-α and IL-8-governed metastatic spreading of ovarian cancer cells in the intraperitoneal cavity. Conclusion: This study highlights the significance of GRO-α and IL-8 as the key chemokines in the peritoneal tumor microenvironment and suggests the utility of targeting their receptor CXCR2 as a potential target-based therapy for peritoneal metastases of ovarian cancer.

Chemokine CXCL-1: activity in the vitreous during proliferative vitreoretinopathy

The aim of this study was to investigate CXCL-1 chemokine levels in the vitreous during rhegmatogenous retinal detachment (RRD) with and without proliferative vitreoretinopathy (PVR) and identify possible correlations with clinical parameters (extent and duration or RRD and PVR grade). Vitreous samples from patients with primary RRD with or without PVR were collected and assayed using a double antibody enzyme-linked immunosorbent assay (ELISA). Eleven vitreous samples from organ donors were employed as a control group. CXCL-1 levels were measured in 35 vitreous samples from 35 RRD patients. Mean CXCL-1 levels (64·82 ± 6·47 pg/ml) were significantly higher (P = 0·048) compared to controls. There was a significant positive correlation between CXCL-1 levels and the extent of the detachment (r = 0·794, P = 0·006). Peak CXCL-1 levels coincided with 3+ quadrant RRD, an interim of 29-60 days' duration and PVR grade B. Increased CXCL-1 levels may be indicative of mild inflammation in the detached retina and the adjacent vitreous. The results of the present study may provide novel insight into the complex interactions taking place during the early and late stages of RRD complicated by PVR.

Redirection of doublecortin-positive cell migration by over-expression of the chemokines MCP-1, MIP-1α and GRO-α in the adult rat brain

Inflammation-induced chemoattraction plays a major role in adult subventricular zone (SVZ)-derived precursor cell migration following neural cell loss, in particular through the release of chemokines by activated microglia and macrophages. We previously demonstrated that monocyte chemotactic protein-1 (MCP-1) (chemokine (c-c motif) ligand (CCL)2), macrophage inflammatory protein-1α (MIP-1α) (CCL3) and growth regulatory protein-α (GRO-α) (chemokine (c-x-c motif) ligand (CXCL)1) are up-regulated following neural cell loss in the adult striatum and act as potent chemoattractants for SVZ-derived precursor cells in vitro. Based on these observations, the current study aimed to examine the individual effect of MCP-1, MIP-1α and GRO-α on the migration of adult SVZ-derived neural precursor cells in vivo. To address this without the confounding effects of injury-induced chemotactic cues, adeno-associated viral (AAV)2-mediated in vivo gene transfer was used to ectopically express either MCP-1, MIP-1α or GRO-α, or the control red fluorescent protein (RFP) in the normal adult rat striatum. The extent of doublecortin (Dcx)-positive cell recruitment from the SVZ into the striatal parenchyma was then determined at 4 and 8weeks following AAV2 injection. Ectopic expression either of MCP-1 or MIP-1α in the normal adult rat brain significantly increased the number of Dcx-positive cells and the extent of their migration into the striatum at both 4 and 8weeks after vector injection but did not promote either precursor cell proliferation or neural differentiation. In contrast, while over-expression of GRO-α 4weeks after vector injection induced a significant increase in Dcx-positive cell migration compared to control, this effect was reduced to control levels by 8weeks post injection. Further, direct comparison between MCP-1, MIP-1α and GRO-α at both 4 and 8weeks post vector injection indicated that GRO-α may have a reduced effect in inducing Dcx-positive cell migration when compared to MCP-1. Combined, these results confirm that over-expression of the chemokines MCP-1, MIP-1α and GRO-α can override cues directing precursor cell migration along the rostral migratory stream (RMS) and provides a mechanism by which neural precursor cell migration can be redirected into a non-neurogenic region. Differences in the migratory effect observed between individual chemokine may be due to ligand-binding affinity and/or receptor expression on SVZ-derived precursor cells.