Increased expression of CXCL6 in secretory cells drives fibroblast collagen synthesis and is associated with increased mortality in idiopathic pulmonary fibrosis.

RATIONALE: Recent data suggest that the localisation of airway epithelial cells in the distal lung in idiopathic pulmonary fibrosis (IPF) may drive pathology. We set out to discover whether chemokines expressed in these ectopic airway epithelial cells may contribute to the pathogenesis of IPF. METHODS: We analysed whole lung and single-cell transcriptomic data obtained from patients with IPF. In addition, we measured chemokine levels in blood, bronchoalveolar lavage (BAL) of IPF patients and air-liquid interface cultures. We employed ex vivo donor and IPF lung fibroblasts and an animal model of pulmonary fibrosis to test the effects of chemokine signalling on fibroblast function. RESULTS: By analysis of whole-lung transcriptomics, protein and BAL, we discovered that CXCL6 (a member of the interleukin-8 family) was increased in patients with IPF. Elevated CXCL6 levels in the BAL of two cohorts of patients with IPF were associated with poor survival (hazard ratio of death or progression 1.89, 95% CI 1.16-3.08; n=179, p=0.01). By immunostaining and single-cell RNA sequencing, CXCL6 was detected in secretory cells. Administration of mCXCL5 (LIX, murine CXCL6 homologue) to mice increased collagen synthesis with and without bleomycin. CXCL6 increased collagen I levels in donor and IPF fibroblasts 4.4-fold and 1.7-fold, respectively. Both silencing of and chemical inhibition of CXCR1/2 blocked the effects of CXCL6 on collagen, while overexpression of CXCR2 increased collagen I levels 4.5-fold in IPF fibroblasts. CONCLUSIONS: CXCL6 is expressed in ectopic airway epithelial cells. Elevated levels of CXCL6 are associated with IPF mortality. CXCL6-driven collagen synthesis represents a functional consequence of ectopic localisation of airway epithelial cells in IPF.

Basic fibroblast growth factor promotes meniscus regeneration through the cultivation of synovial mesenchymal stem cells via the CXCL6-CXCR2 pathway.

OBJECTIVE: To investigate the efficacy of basic fibroblast growth factor (bFGF) in promoting meniscus regeneration by cultivating synovial mesenchymal stem cells (SMSCs) and to validate the underlying mechanisms. METHODS: Human SMSCs were collected from patients with osteoarthritis. Eight-week-old nude rats underwent hemi-meniscectomy, and SMSCs in pellet form, either with or without bFGF (1.0 × 106 cells per pellet), were implanted at the site of meniscus defects. Rats were divided into the control (no transplantation), FGF (-) (pellet without bFGF), and FGF (+) (pellet with bFGF) groups. Different examinations, including assessment of the regenerated meniscus area, histological scoring of the regenerated meniscus and cartilage, meniscus indentation test, and immunohistochemistry analysis, were performed at 4 and 8 weeks after surgery. RESULTS: Transplanted SMSCs adhered to the regenerative meniscus. Compared with the control group, the FGF (+) group had larger regenerated meniscus areas, superior histological scores of the meniscus and cartilage, and better meniscus mechanical properties. RNA sequencing of SMSCs revealed that the gene expression of chemokines that bind to CXCR2 was upregulated by bFGF. Furthermore, conditioned medium derived from SMSCs cultivated with bFGF exhibited enhanced cell migration, proliferation, and chondrogenic differentiation, which were specifically inhibited by CXCR2 or CXCL6 inhibitors. CONCLUSION: SMSCs cultured with bFGF promoted the expression of CXCL6. This mechanism may enhance cell migration, proliferation, and chondrogenic differentiation, thereby resulting in superior meniscus regeneration and cartilage preservation.

Allicin May Promote Reversal of T-Cell Dysfunction in Periodontitis via the PD-1 Pathway.

We evaluated the role of allicin in periodontitis using an in silico and in vitro design. An in silico docking analysis was performed to assess the plausible interactions between allicin and PD-L1. The cytokine profile of gingival crevicular fluid (GCF) samples obtained from periodontitis patients was estimated by cytometric bead array. CD3+ lymphocytes isolated from the peripheral blood were sorted and characterized using immunomagnetic techniques. Cultured and expanded lymphocytes were treated with the GCF samples to induce T-cell exhaustion. Optimum concentrations of allicin were added to exhausted lymphocytes to compare the expression of TIM-3 and LAG-3 gene expression at baseline and post-treatment. Allicin was found to bind to the PD-L1 molecule as revealed by the in-silico experiment, which is possibly an inhibitory interaction although not proven. GCF from periodontitis patients had significantly higher concentrations of TNF-α, CCL2, IL-6, IFN-γ, and CXCL8 than controls. GCF treatment of CD3+ lymphocytes from the periodontitis patients significantly increased expression of T-cell exhaustion markers TIM-3 and LAG-3. Allicin administration with GCF treatment resulted in significant lowering of the expression of exhaustion markers. Allicin may exert an immunostimulatory role and reverse immune-destructive mechanisms such as T-cell exhaustion.

Cancer-Associated Fibroblast-Mediated Cellular Crosstalk Supports Hepatocellular Carcinoma Progression.

BACKGROUND AND AIMS: Cancer-associated fibroblasts (CAFs) are key players in multicellular, stromal-dependent alterations leading to HCC pathogenesis. However, the intricate crosstalk between CAFs and other components in the tumor microenvironment (TME) remains unclear. This study aimed to investigate the cellular crosstalk among CAFs, tumor cells, and tumor-associated neutrophils (TANs) during different stages of HCC pathogenesis. APPROACH AND RESULTS: In the HCC-TME, CAF-derived cardiotrophin-like cytokine factor 1 (CLCF1) increased chemokine (C-X-C motif) ligand 6 (CXCL6) and TGF-ß secretion in tumor cells, which subsequently promoted tumor cell stemness in an autocrine manner and TAN infiltration and polarization in a paracrine manner. Moreover, CXCL6 and TGF-ß secreted by HCC cells activated extracellular signal-regulated kinase (ERK) 1/2 signaling of CAFs to produce more CLCF1, thus forming a positive feedback loop to accelerate HCC progression. Inhibition of ERK1/2 or CLCF1/ciliary neurotrophic factor receptor signaling efficiently impaired CLCF1-mediated crosstalk among CAFs, tumor cells, and TANs both in vitro and in vivo. In clinical samples, up-regulation of the CLCF1-CXCL6/TGF-ß axis exhibited a marked correlation with increased cancer stem cells, "N2"-polarized TANs, tumor stage, and poor prognosis. CONCLUSIONS: This study reveals a cytokine-mediated cellular crosstalk and clinical network involving the CLCF1-CXCL6/TGF-ß axis, which regulates the positive feedback loop among CAFs, tumor stemness, and TANs, HCC progression, and patient prognosis. These results may support the CLCF1 cascade as a potential prognostic biomarker and suggest that selective blockade of CLCF1/ciliary neurotrophic factor receptor or ERK1/2 signaling could provide an effective therapeutic target for patients with HCC.

CXCL6 fuels the growth and metastases of esophageal squamous cell carcinoma cells both in vitro and in vivo through upregulation of PD-L1 via activation of STAT3 pathway.

CXCL6, contraction of C-X-C motif chemokine ligand 6, whose biological roles have been rarely described in esophageal squamous cell carcinoma (ESCC). To understand the clinicopathological and biological roles played by CXCL6 in the growth and metastasis of ESCC, immunohistochemistry was used to detect the expression of CXCL6 in ESCC tissues, totaling 105 cases; and the correlation was statistically analyzed between CXCL6 expression and clinicopathological parameters. The role mediated in migration and invasion was evaluated using wound-healing and Transwell assays. MTT and flow cytometry were used to assay the proliferative variation. In vivo, tail vein injection model was established in nude mice xenografted with human ESCC cell lines whose CXCL6 were artificially manipulated. It was found that relative to normal control, CXCL6 was profoundly higher in ESCC; upregulated CXCL6 only significantly correlated with differentiation degree. In vitro, CXCL6 was found to promote the proliferation, migration, and invasion of ESCC cells; which was fully corroborated by nude mice experiment that CXCL6 can promote the growth and metastases of ESCC cells in vivo. Mechanistically, CXCL6 was discovered to be capable of promoting epithelial-mesenchymal transition and upregulating PD-L1 expression through activation of the STAT3 pathway. Collectively, all the data we showed here demonstrate that CXCL6 can enhance the growth and metastases of ESCC cells both in vivo and in vitro.

CXCL6 regulates cell permeability, proliferation, and apoptosis after ischemia-reperfusion injury by modulating Sirt3 expression via AKT/FOXO3a activation.

Chemokine (C-X-C motif) ligand 6 (CXCL6), a member of the CXC chemokine family, reportedly mediates several processes such as inflammation, immunoreaction, cell growth, and metastasis through interaction with the chemokine receptors CXCR1 and CXCR2 in humans; further, CXCR1 and CXCR2 can promote repair and regeneration of organs or tissues after ischemia-reperfusion injury (IRI). In this study, we found that HIF-1α, CXCL6, and CXCR2 expression levels were elevated in human brain microvascular endothelial cells (HBMECs) after IRI, whereas silent information regulator of transcription (Sirt) 3 expression level had reduced. HIF-1α inhibition in an IRI model potently promoted HBMEC proliferation, accompanied by increased Sirt3 and decreased CXCL6/CXCR2 expression levels. CXCL6 knockdown in the IRI model significantly decreased HBMEC permeability and promoted HBMEC proliferation, concurrent with a decrease in apoptosis; it also increased Sirt3 expression levels and decreased CXCL6/CXCR2 protein and phosphorylated AKT (p-AKT) and class O of forkhead box (FOXO) 3a (p-FOXO3a) levels. In addition, CXCL6-induced HBMEC permeability and inhibition of HBMEC proliferation were counteracted by Sirt3 overexpression, and the AKT inhibitor LY294002 counteracted the effect of CXCL6 recombinant proteins on Sirt3, p-AKT, and p-FOXO3a expressions. These results suggest that CXCL6 and Sirt3 are downstream of HIF-1α and that CXCL6 regulatesHBMEC permeability, proliferation, and apoptosis after IRI by modulating Sirt3 expression via AKT/FOXO3a activation.

Hypoxia-CXCL6 axis affects arteriolar niche remodeling in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a malignant clonal disease derived from hematopoietic stem/progenitor cell. Leukemia blasts cause extensive hypoxia of bone marrow (BM), which lead to disorder and remodeling of BM niche, thereby becoming "leukemic niche" to support the development and drug-resistance of AML as well as the maintenance of normal hematopoietic stem cells. In this study, the biological characteristics (such as self-renewal, apoptosis, migration, autocrine) and function (vascularization) of mesenchymal stem cells (MSCs) and human umbilical artery endothelial cells (HUAECs) that make up BM arteriolar niche in simulated hypoxia AML context were investigated. It was found that moderate hypoxia enhanced the viability of the arteriolar niche cells, but severe hypoxia of AML BM resulted in the damage of arteriolar niche cells and the disorder of vascular cytokines C-X-C motif chemokine ligand 6 (CXCL6). The dynamic changes of CXCL6 in the system as well as its anti-apoptotic and promoting angiogenic effects suggested that CXCL6 played an important role in the remodeling of BM arteriolar niche in AML. Taking advantage of CXCL6 can save the damaged MSCs and HUAECs, which is the hope of rescuing arteriolar niche. It is suggested that CXCL6 may be an assistant strategy for microenvironment targeted therapy of AML.

Biological Characterization of Commercial Recombinantly Expressed Immunomodulating Proteins Contaminated with Bacterial Products in the Year 2020: The SAA3 Case.

The serum amyloid A (SAA) gene family is highly conserved and encodes acute phase proteins that are upregulated in response to inflammatory triggers. Over the years, a considerable amount of literature has been published attributing a wide range of biological effects to SAAs such as leukocyte recruitment, cytokine and chemokine expression and induction of matrix metalloproteinases. Furthermore, SAAs have also been linked to protumorigenic, proatherogenic and anti-inflammatory effects. Here, we investigated the biological effects conveyed by murine SAA3 (mu rSAA3) recombinantly expressed in Escherichia coli. We observed the upregulation of a number of chemokines including CCL2, CCL3, CXCL1, CXCL2, CXCL6 or CXCL8 following stimulation of monocytic, fibroblastoid and peritoneal cells with mu rSAA3. Furthermore, this SAA variant displayed potent in vivo recruitment of neutrophils through the activation of TLR4. However, a major problem associated with proteins derived from recombinant expression in bacteria is potential contamination with various bacterial products, such as lipopolysaccharide, lipoproteins and formylated peptides. This is of particular relevance in the case of SAA as there currently exists a discrepancy in biological activity between SAA derived from recombinant expression and that of an endogenous source, i.e. inflammatory plasma. Therefore, we subjected commercial recombinant mu rSAA3 to purification to homogeneity via reversed-phase high-performance liquid chromatography (RP-HPLC) and re-assessed its biological potential. RP-HPLC-purified mu rSAA3 did not induce chemokines and lacked in vivo neutrophil chemotactic activity, but retained the capacity to synergize with CXCL8 in the activation of neutrophils. In conclusion, experimental results obtained when using proteins recombinantly expressed in bacteria should always be interpreted with care.

Pristane/Hypoxia (PriHx) Mouse as a Novel Model of Pulmonary Hypertension Reflecting Inflammation and Fibrosis.

BACKGROUND: Pulmonary arterial hypertension (PAH), particularly connective tissue disease-associated PAH (CTD-PAH), is a progressive disease and novel therapeutic agents based on the specific molecular pathogenesis are desired. In the pathogenesis of CTD-PAH, inflammation, immune cell abnormality, and fibrosis play important roles. However, the existing mouse pulmonary hypertension (PH) models do not reflect these features enough. The relationship between inflammation and hypoxia is still unclear.Methods and Results:Intraperitoneal administration of pristane, a kind of mineral oil, and exposure to chronic hypoxia were combined, and this model is referred to as pristane/hypoxia (PriHx) mice. Hemodynamic and histological analyses showed that the PriHx mice showed a more severe phenotype of PH than pristane or hypoxia alone. Immunohistological and flow cytometric analyses revealed infiltration of immune cells, including hemosiderin-laden macrophages and activated CD4+helper T lymphocytes in the lungs of PriHx mice. Pristane administration exacerbated lung fibrosis and elevated the expression of fibrosis-related genes. Inflammation-related genes such asIl6andCxcl2were also upregulated in the lungs of PriHx mice, and interleukin (IL)-6 blockade by monoclonal anti-IL-6 receptor antibody MR16-1 ameliorated PH of PriHx mice. CONCLUSIONS: A PriHx model, a novel mouse model of PH reflecting the pathological features of CTD-PAH, was developed through a combination of pristane administration and exposure to chronic hypoxia.

Circ-HOMER1 enhances the inhibition of miR-1322 on CXCL6 to regulate the growth and aggressiveness of hepatocellular carcinoma cells.

Hepatocellular carcinoma (HCC) is a common liver malignancy worldwide accompanying with the high rate of recurrence. Accumulating reports have documented the significance of circular RNAs (circRNAs) in carcinogenesis and development of HCC. This study aimed to establish the mechanism underlying circ-HOMER1 involvement in HCC. To this end, we identified a binding site for miR-1322 via bioinformatics, quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), and dual-luciferase reporter assays providing evidence of a direct link between circ-HOMER1 and miR-1322. Similarly, the target gene of miR-1322 was investigated. Moreover, we determined the specific function of circ-HOMER1 in HCC with the aid of qRT-PCR based on patient clinical records, Cell Counting Kit-8, acridine orange/ethidium bromide double fluorescence staining, flow cytometry, and wound-healing and transwell assays. Notably, circ-HOMER1 was upregulated in both HCC cells and tissues. This aberrant expression pattern was closely correlated with larger tumor size, higher tumor-node-metastasis stage, and poorer prognosis for the patients with HCC. Moreover, silenced circ-HOMER1 inhibited cell proliferation, migration, and invasion concomitant with the promotion of apoptosis in HCC cells, and vice versa. Mechanistically, circ-HOMER1 enhanced the inhibition of miR-1322 on CXCL6 in HCC. Furthermore, we found that circ-HOMER1 promoted HCC cell growth and aggressiveness by miR-1322/CXCL6 axis. This study may provide a potential prognostic indicator and therapeutic target for patients with HCC.

The Clinicopathological Significance of the CXCR2 Ligands, CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL7, and CXCL8 in Gastric Cancer.

BACKGROUND/AIM: We have previously reported that chemokine (C-X-C motif) receptor 2 (CXCR2) signaling was associated with the malignant progression of gastric cancer (GC). We thus examined the clinicopathological significance of CXCR2 ligands, CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL7, and CXCL8, in GC. PATIENTS AND METHODS: The expression of CXCR2 ligands in 590 GC cases was investigated by immunohistochemistry. RESULTS: The expression was as follows: CXCL1, 46.2% (257/557); CXCL2, 20.7% (122/590); CXCL3, 17.1% (101/589); CXCL5/CXCL6, 2.9% (17/589); CXCL7, 36.4% (215/590); and CXCL8 1.7% (10/585) of the cases. High invasion depth was correlated with CXCL1 expression. Lymph node metastasis and peritoneal cytology positivity were correlated with high expression of CXCL1 and CXCL7. The prognoses of the CXCL1-positive patients were significantly poorer than those of the CXCL1-negative patients (p<0.001). CONCLUSION: Among the CXCR2 ligands, CXCL7 and especially CXCL1, might play an important role in the malignant progression of GC via CXCR2 signaling.

Using Statistical Modeling to Understand and Predict Pediatric Stem Cell Function.

BACKGROUND: Congenital heart defects are a leading cause of morbidity and mortality in children, and despite advanced surgical treatments, many patients progress to heart failure. Currently, transplantation is the only effective cure and is limited by donor availability and organ rejection. Recently, cell therapy has emerged as a novel method for treating pediatric heart failure with several ongoing clinical trials. However, efficacy of stem cell therapy is variable, and choosing stem cells with the highest reparative effects has been a challenge. METHODS: We previously demonstrated the age-dependent reparative effects of human c-kit+ progenitor cells (hCPCs) in a rat model of juvenile heart failure. Using a small subset of patient samples, computational modeling analysis showed that regression models could be made linking sequencing data to phenotypic outcomes. In the current study, we used a similar quantitative model to determine whether predictions can be made in a larger population of patients and validated the model using neonatal hCPCs. We performed RNA sequencing from c-kit+ progenitor cells isolated from 32 patients, including 8 neonatal samples. We tested 2 functional parameters of our model, cellular proliferation and chemotactic potential of conditioned media. RESULTS: Interestingly, the observed proliferation and migration responses in each of the selected neonatal hCPC lines matched their predicted counterparts. We then performed canonical pathway analysis to determine potential mechanistic signals that regulated hCPC performance and identified several immune response genes that correlated with performance. ELISA analysis confirmed the presence of selected cytokines in good performing hCPCs and provided many more signals to further validate. CONCLUSIONS: These data show that cell behavior may be predicted using large datasets like RNA sequencing and that we may be able to identify patients whose c-kit+ progenitor cells exceed or underperform expectations. With systems biology approaches, interventions can be tailored to improve cell therapy or mimic the qualities of reparative cells.

MicroRNA-101-5p inhibits the growth and metastasis of cervical cancer cell by inhibiting CXCL6.

OBJECTIVE: The objective of this study is to explore the biological roles of microRNA-101-5p (miR-101-5p) in the growth and metastasis of cervical cancer. PATIENTS AND METHODS: The levels of miR-101-5p and chemokine (C-X-C motif) ligand 6 (CXCL6) in cervical cancer tissues and cells were detected using the quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) assay. The proliferation, colony formation, migration, and invasion assays were conducted using miR-101-5p transfected cervical cancer cell. The expression of CXCL6 was measured by the immunoblotting assay. Xenograft model was constructed to reveal the precise roles of miR-101-5p in the growth of cervical cancer cell in vivo. RESULTS: MiR-101-5p was down-regulated in cervical cancer tissues when compared to the normal controls. The levels of miR-101-5p were higher in cervical cancer cells (SiHa, Caski, C-4-I, C-33 A) than that in the human cervical surface epithelial cell line, HcerEpic. Over-regulation of miR-101-5p inhibited the aggressiveness phenotypes of a cervical cancer cell in vitro. Furthermore, over-regulation of miR-101-5p reduced the tumor growth of cervical cancer cell in vivo. CXCL6 was the target protein of miR-101-5p in cervical cancer as demonstrated by luciferase reporter assay. The mRNA level of CXCL6 was negatively associated with the miR-101-5p level in cervical cancer tissue. Finally, the rescue experiments suggested that the inhibitory role of miR-101-5p was mediated by regulating the expression of CXCL6 in cervical cancer. CONCLUSIONS: These findings indicated that the over-regulation of miR-101-5p suppressed the progression of cervical cancer by targeting CXCL6 and might function as a potential therapeutic target for cervical cancer.

Human adipose mesenchymal stem cells overexpressing dual chemotactic gene showed enhanced angiogenic capacity in ischaemic hindlimb model.

Aims: In present study, we sought to characterize the angio-vasculogenic property of human adipose mesenchymal stem cells (ASCs) overexpressing dual chemokine GCP-2 and SDF-1α (ASC-G/S) and to determine the therapeutic potential of ASC-G/S in the context of experimental ischaemia. Methods and results: We generated ASC-G/S line and performed flow cytometry, quantitative (q)-PCR, Matrigel tube formation, Matrigel plug assays, and in vivo therapeutic assays using hind limb ischaemia mouse model. Q-PCR results showed that the representative pro-angiogenic factors were highly upregulated in ASC-G/S compared with ASCs single chemokine overexpressing GCP-2 (ASC-G). In addition, ASC-G/S exhibited high expression of endothelium-specific genes shch as vWF and Flk-1 and showed robust in vitro micro-vascular formation. ASC-G/S was transplanted into ischaemic mouse hind limbs and compared with control groups. ASC-G/S injection prevented limb loss and augmented blood perfusion, suggesting that ASC-G/S enhances neovascularization in hind limb ischaemia. In addition, transplanted ASC-G/S revealed high vasculogenic potential in vivo compared with transplanted ASC-G. Conclusion: Our data suggest that ASC-G/S has high therapeutic effects on hind limb ischaemia via robust angiogenic and vasculogenic action.

CXCL6 promotes non-small cell lung cancer cell survival and metastasis via down-regulation of miR-515-5p.

Chemokine plays an important role in lung cancer and CXCL6 is one of chemokine, however, its effect on miRNAs profile and its roles in non-small cell lung cancer cell (NSCLC) is not elucidated. This study is purposed to explore the influence of CXCL6 on miRNA expression profile and found that CXCL6 could reduce the expression of miR-515-5p in NSCLC cells. MiR-515-5p in NSCLC cells could inhibit NSCLC survival and metastasis. MiR-515-5p acted as a tumor suppressor by targeting CXCL6 in NSCLC cells. These data highlighted a novel molecular interaction between miR-515-5p and CXCL6. MiR-515-5p may constitute a potential therapy target for NSCLC.

CXCL6 is an important paracrine factor in the pro-angiogenic human cardiac progenitor-like cell secretome.

Studies in recent years have established that the principal effects in cardiac cell therapy are associated with paracrine/autocrine factors. We combined several complementary techniques to define human cardiac progenitor cell (CPC) secretome constituted by 914 proteins/genes; 51% of these are associated with the exosomal compartment. To define the set of proteins specifically or highly differentially secreted by CPC, we compared human mesenchymal stem cells and dermal fibroblasts; the study defined a group of growth factors, cytokines and chemokines expressed at high to medium levels by CPC. Among them, IL-1, GROa (CXCL1), CXCL6 (GCP2) and IL-8 are examples whose expression was confirmed by most techniques used. ELISA showed that CXCL6 is significantly overexpressed in CPC conditioned medium (CM) (18- to 26-fold) and western blot confirmed expression of its receptors CXCR1 and CXCR2. Addition of anti-CXCL6 completely abolished migration in CPC-CM compared with anti-CXCR2, which promoted partial inhibition, and anti-CXCR1, which was inefficient. Anti-CXCL6 also significantly inhibited CPC CM angiogenic activity. In vivo evaluation also supported a relevant role for angiogenesis. Altogether, these results suggest a notable angiogenic potential in CPC-CM and identify CXCL6 as an important paracrine factor for CPC that signals mainly through CXCR2.

Fibroblast-derived CXCL12/SDF-1α promotes CXCL6 secretion and co-operatively enhances metastatic potential through the PI3K/Akt/mTOR pathway in colon cancer.

AIM: To investigate the underlying mechanism by which CXCL12 and CXCL6 influences the metastatic potential of colon cancer and internal relation of colon cancer and stromal cells. METHODS: Western blotting was used to detect the expression of CXCL12 and CXCL6 in colon cancer cells and stromal cells. The co-operative effects of CXCL12 and CXCL6 on proliferation and invasion of colon cancer cells and human umbilical vein endothelial cells (HUVECs) were determined by enzyme-linked immunosorbent assay, and proliferation and invasion assays. The angiogenesis of HUVECs through interaction with cancer cells and stromal cells was examined by angiogenesis assay. We eventually investigated activation of PI3K/Akt/mTOR signaling by CXCL12 involved in the metastatic process of colon cancer. RESULTS: CXCL12 was expressed in DLD-1 cancer cells and fibroblasts. The secretion level of CXCL6 by colon cancer cells and HUVECs were significantly promoted by fibroblasts derived from CXCL12. CXCL6 and CXCL2 could significantly enhance HUVEC proliferation and migration (P < 0.01). CXCL6 and CXCL2 enhanced angiogenesis by HUVECs when cultured with fibroblast cells and colon cancer cells (P < 0.01). CXCL12 also enhanced the invasion of colon cancer cells. Stromal cell-derived CXCL12 promoted the secretion level of CXCL6 and co-operatively promoted metastasis of colon carcinoma through activation of the PI3K/Akt/mTOR pathway. CONCLUSION: Fibroblast-derived CXCL12 enhanced the CXCL6 secretion of colon cancer cells, and both CXCL12 and CXCL6 co-operatively regulated the metastasis via the PI3K/Akt/mTOR signaling pathway. Blocking this pathway may be a potential anti-metastatic therapeutic target for patients with colon cancer.

Fli1 Deficiency Induces CXCL6 Expression in Dermal Fibroblasts and Endothelial Cells, Contributing to the Development of Fibrosis and Vasculopathy in Systemic Sclerosis.

OBJECTIVE: CXCL6, a chemokine with proangiogenic property, is reported to be involved in vasculopathy associated with systemic sclerosis (SSc). We investigated the contribution of CXCL6 to SSc development by focusing on the association of friend leukemia virus integration 1 (Fli1) deficiency, a potential predisposing factor of SSc, with CXCL6 expression and clinical correlation of serum CXCL6 levels. METHODS: mRNA levels of target genes and the binding of Fli1 to the CXCL6 promoter were evaluated by quantitative reverse transcription-PCR and chromatin immunoprecipitation, respectively. Serum CXCL6 levels were determined by ELISA. RESULTS: FLI1 siRNA significantly enhanced CXCL6 mRNA expression in human dermal fibroblasts and human dermal microvascular endothelial cells, while Fli1 haploinsufficiency significantly suppressed CXCL6 mRNA expression in murine peritoneal macrophages stimulated with lipopolysaccharide. Supporting a critical role of Fli1 deficiency to induce SSc-like phenotypes, CXCL6 mRNA expression was higher in SSc dermal fibroblasts than in normal dermal fibroblasts. Importantly, Fli1 bound to the CXCL6 promoter in dermal fibroblasts, endothelial cells, and THP-1 cells. In patients with SSc, serum CXCL6 levels correlated positively with the severity of dermal and pulmonary fibrosis and were elevated in association with cardiac and pulmonary vascular involvement and cutaneous vascular symptoms, including Raynaud phenomenon, digital ulcers (DU)/pitting scars, and telangiectasia. Especially, serum CXCL6 levels were associated with DU/pitting scars and heart involvement by multiple regression analysis. CONCLUSION: CXCL6 expression is upregulated by Fli1 deficiency in fibroblasts and endothelial cells, potentially contributing to the development of fibrosis and vasculopathy in the skin, lung, and heart of SSc.

The cell wall component lipoteichoic acid of Staphylococcus aureus induces chemokine gene expression in bovine mammary epithelial cells.

Staphylococcus aureus (SA) is a major cause of bovine mastitis, but its pathogenic mechanism remains poorly understood. To evaluate the role of lipoteichoic acid (LTA) in the immune or inflammatory response of SA mastitis, we investigated the gene expression profile in bovine mammary epithelial cells stimulated with LTA alone or with formalin-killed SA (FKSA) using cap analysis of gene expression. Seven common differentially expressed genes related to immune or inflammatory mediators were up-regulated under both LTA and FKSA stimulations. Three of these genes encode chemokines (IL-8, CXCL6 and CCL2) functioning as chemoattractant molecules for neutrophils and macrophages. These results suggest that the initial inflammatory response of SA infection in mammary gland may be related with LTA induced chemokine genes.