CXCL16 Promotes Gastric Cancer Tumorigenesis via ADAM10-Dependent CXCL16/CXCR6 Axis and Activates Akt and MAPK Signaling Pathways

Abnormal expression of CXC motif chemokine ligand 16 (CXCL16) has been demonstrated to be associated with tumor progression and metastasis, served as a prognostic factor in many cancers, with higher relative expression behaving as a marker of tumor progression. However, its role and mechanisms underlying progression and metastasis of gastric cancer (GC) are yet to be elucidated. In our investigation, public datasets and human GC tissue samples were used to determine the CXCL16 expression levels. Our results revealed that CXCL16 was upregulated in GC. The high expression CXCL16 in GC was significantly associated with histologic poor differentiation and pTNM staging. And high CXCL16 was positively correlated with the poor survival of GC patients. Gain-and loss-of-function experiments were employed to investigate the biological role of CXCL16 in proliferation and migration both in vitro and in vivo. Mechanically, Gene set enrichment analysis (GSEA) revealed that the epithelial‑mesenchymal transition (EMT), Akt and MAPK signal pathway related genes were significantly enriched in the high CXCL16 group, which was confirmed by western blot. Moreover, overexpression CXCL16 promoted the disintegrin and metalloproteases (ADAM10) and the CXC motif chemokine receptor 6 (CXCR6) expression, which mediated the CXCL16/CXCR6 positive feedback loop in GC, with activating Akt and MAPK signaling pathways. Knocking down ADAM10 would interrupted the CXCL16/CXCR6 axis in the carcinogenesis and progression of GC. In conclusion, our findings offered insights into that CXCL16 promoted GC tumorigenesis by enhancing ADAM10-dependent CXCL16/CXCR6 axis activation.     

Stroma-derived factor (SDF-1/CXCL12) and human tumor pathogenesis

The chemokine stroma-derived factor (SDF-1/CXCL12) plays multiple roles in tumor pathogenesis. It has been demonstrated that CXCL12 promotes tumor growth and malignancy, enhances tumor angiogenesis, participates in tumor metastasis, and contributes to immunosuppressive networks within the tumor microenvironment. Therefore, it stands to reason that the CXCL12/CXCR4 pathway is an important target for the development of novel anti-cancer therapies. In this review, we consider the pathological nature and characteristics of the CXCL12/CXCR4 pathway in the tumor microenvironment. Strategies for therapeutically targeting the CXCL12/CXCR4 axis also are discussed. migration; immune suppression; tumor angiogenesis; tumor metastasis; stem cells     

miR-449c-5p availability is antagonized by circ-NOTCH1 for MYC-induced NOTCH1 upregulation as well as tumor metastasis and stemness in gastric cancer

Gastric cancer (GC), identified as the most common gastrointestinal malignancy, is one of the primary causes of cancer-related mortality in the world. Although surgery and chemotherapy for GC treatment have been improved, the 5-year overall survival rate is still unsatisfactory. Circ-NOTCH1 is a novel circular RNA derived from its host gene NOTCH1, and has not been studied in any cancers. Here we explored the potential role and mediatory mechanism of circ-NOTCH1 in GC. In this study, circ-NOTCH1 exhibited increased expression in GC tissues and cells. Suppression of circ-NOTCH1 inhibited cell migration, invasion, tumor spheroids number, and side population ratio. Circ-NOTCH1 also promoted GC growth and metastasis in vivo. Additionally, it was found that circ-NOTCH1 could bind to miR-449c-5p. Circ-NOTCH1 promoted metastasis and stemness in GC through sponging miR-449c-5p. Subsequently, MYC was identified as a downstream gene of miR-449c-5p. MYC could bind to the promoter of NOTCH1 to regulate GC progression. Furthermore, rescue assays demonstrated that NOTCH1 knockdown reversed the effects of overexpression of MYC in metastasis and stemness in AGS cells/sh-circNOTCH1. Above findings explained that circ-NOTCH1 promoted metastasis and stemness in GC by targeting miR-449c-5p/MYC/NOTCH1 axis, suggesting the possibility of circ-NOTCH1 as a therapeutic marker for GC.     

Follicular dendritic cell regulation of CXCR4-mediated germinal center CD4 T cell migration

Follicular dendritic cells (FDCs) up-regulate the chemokine receptor CXCR4 on CD4 T cells, and a major subpopulation of germinal center (GC) T cells (CD4(+)CD57(+)), which are adjacent to FDCs in vivo, expresses high levels of CXCR4. We therefore reasoned that GC T cells would actively migrate to stromal cell-derived factor-1 (CXCL12), the CXCR4 ligand, and tested this using Transwell migration assays with GC T cells and other CD4 T cells (CD57(-)) that expressed much lower levels of CXCR4. Unexpectedly, GC T cells were virtually nonresponsive to CXCL12, whereas CD57(-)CD4 T cells migrated efficiently despite reduced CXCR4 expression. In contrast, GC T cells efficiently migrated to B cell chemoattractant-1/CXCL13 and FDC supernatant, which contained CXCL13 produced by FDCs. Importantly, GC T cell nonresponsiveness to CXCL12 correlated with high ex vivo expression of regulator of G protein signaling (RGS), RGS13 and RGS16, mRNA and expression of protein in vivo. Furthermore, FDCs up-regulated both RGS13 and RGS16 mRNA expression in non-GC T cells, resulting in their impaired migration to CXCL12. Finally, GC T cells down-regulated RGS13 and RGS16 expression in the absence of FDCs and regained migratory competence to CXCL12. Although GC T cells express high levels of CXCR4, signaling through this receptor appears to be specifically inhibited by FDC-mediated expression of RGS13 and RGS16. Thus, FDCs appear to directly affect GC T cell migration within lymphoid follicles.     

Baohuoside i suppresses breast cancer metastasis by downregulating the tumor-associated macrophages/C-X-C motif chemokine ligand 1 pathway

BackgroundBreast cancer is the most common malignancy in women and metastasis is the leading cause of breast cancer-related deaths. Our previous studies have shown that XIAOPI formula, a newly approved drug by the State Food and Drug Administration of China (SFDA), can dramatically inhibit breast cancer metastasis by modulating the tumor-associated macrophages/C-X-C motif chemokine ligand 1 (TAMs/CXCL1) pathway. However, the bioactive compound accounting for the anti-metastatic effect of XIAOPI formula remains unclear.PurposeThis study was designed to separate the anti-metastatic bioactive compound from XIAOPI formula and to elucidate its action mechanisms.Study Design/MethodsTAMs/CXCL1 promoter activity-guided fractionation and multiple chemical structure identification approaches were conducted to screen the bioactive compound from XIAOPI formula. Breast cancer cells and TAMs were co-cultured in vitro or co-injected in vivo to simulate their coexistence. Multiple molecular biology experiments, zebrafish breast cancer xenotransplantation model and mouse breast cancer xenografts were applied to validate the anti-metastatic activity of the screened compound.ResultsBioactivity-guided fractionation identified baohuoside I (BHS) as the key bioactive compound of XIAOPI formula in inhibiting TAMs/CXCL1 promoter activity. Functional studies revealed that BHS could significantly inhibit the migration and invasion as well as the expression of metastasis-related proteins in both human and mouse breast cancer cells, along with decreasing the proportion of breast cancer stem cells (CSCs). Furthermore, BHS could suppress the M2 phenotype polarization of TAMs and therefore attenuate their CXCL1 expression and secretion. Notably, mechanistic investigations validated TAMs/CXCL1 as the crucial target of BHS in suppressing breast cancer metastasis as exogenous addition of CXCL1 significantly abrogated the anti-metastatic effect of BHS on breast cancer cells. Moreover, BHS was highly safe in vivo as it exhibited no observable embryotoxicity or teratogenic effect on zebrafish embryos. More importantly, BHS remarkably suppressed breast cancer metastasis and TAMs/CXCL1 activity in both zebrafish breast cancer xenotransplantation model and mouse breast cancer xenografts.ConclusionThis study not only provides novel insights into TAMs/CXCL1 as a reliable screening target for anti-metastatic drug discovery, but also suggests BHS as a promising candidate drug for metastatic breast cancer treatment.     

CXCR6/CXCL16 functions as a regulator in metastasis and progression of cancer

Metastasis is considered the obvious mark for most aggressive cancers. However, little is known about the molecular mechanism of the regulation of cancer metastasis. Recent evidence increasingly suggests that the interaction between chemokines and chemokine receptors is pivotal in the process of metastasis. The chemokine receptor CXCR4 and its ligand CXCL12, for example, have been reported to play a vital role in cancer metastasis. Another chemokine and chemokine receptor pair, the CXCL16/CXCR6 axis, has been studied by several independent research groups. Here, we summarize recent advances in our knowledge of the function of CXC chemokine receptor CXCR6 and its ligand CXCL16 in regulating metastasis and invasion of cancer. CXCR6 and CXCL16 are up-regulated in multiple cancer tissue types and cancer cell lines relative to normal tissues and cell lines. In addition, both CXCR6 and CXCL16 levels increase as tumor malignancy increases. Trans-membranous CXCL16 chemokine reduces proliferation while soluble CXCL16 chemokine enhances proliferation and migration. TM-CXCL16 functions as an inducer for lymphocyte build-up around tumor sites. High trans-membranous CXCL16 expression correlates with a good prognosis. Moreover, the Akt/mTOR signal pathway is involved in activating the CXCR6/CXCL16 axis. These findings suggest multiple opportunities for blocking the CXCR6/CXCL16 axis and the Akt/mTOR signal pathway in novel cancer therapies.     

Long noncoding RNA POU3F3 promotes cancer cell proliferation in prostate carcinoma by upregulating rho-associated protein kinase 1

Long noncoding RNAs (lncRNAs) POU3F3 is overexpressed in esophageal squamous-cell carcinomas, while its role in other human cancers is unclear. In this study we found that POU3F3 and rho-associated protein kinase 1 (ROCK1) were both increased in tumor tissues than in adjacent healthy tissues of patients with prostate carcinoma. Expression levels of POU3F3 increased with increase in the diameter of tumor but were not significantly affected by lymph node metastasis or distant metastasis. Expression levels of POU3F3 and ROCK1 were positive correlated in tumor tissues but not in adjacent healthy tissues. POU3F3 and ROCK1 overexpression promoted, while ROCK1 knockdown inhibited the proliferation of prostate carcinoma cells. ROCK1 knockdown reduced the enhancing effect of POU3F3 overexpression on cancer cell proliferation. POU3F3 overexpression led to ROCK1 overexpression in prostate carcinoma cells, while ROCK1 overexpression did not significantly affect POU3F3 expression. Therefore, lncRNA POU3F3 may promote cancer cell proliferation in prostate carcinoma by upregulating ROCK1.     

Piezo type mechanosensitive ion channel component 1 facilitates gastric cancer omentum metastasis

The peritoneum, especially the omentum, is a common site for gastric cancer (GC) metastasis. Our aim was to expound the role and mechanisms of Piezo1 on GC omentum metastasis. A series of functional assays were performed to examine cell proliferation, clone formation, apoptosis, Ca²⁺ influx, mitochondrial membrane potential (MMP) and migration after overexpression or knockdown of Piezo1. A GC peritoneal implantation and metastasis model was conducted. After infection by si-Piezo1, the number and growth of tumours were observed in abdominal cavity. Fibre and angiogenesis were tested in metastatic tumour tissues. Piezo1 had higher expression in GC tissues with omentum metastasis and metastatic lymph node tissues than in GC tissues among 110 patients. High Piezo1 expression was associated with lymph metastasis, TNM and distant metastasis. Overexpressed Piezo1 facilitated cell proliferation and suppressed cell apoptosis in GC cells. Moreover, Ca²⁺ influx was elevated after up-regulation of Piezo1. Piezo1 promoted cell migration and Calpain1/2 expression via up-regulation of HIF-1α in GC cells. In vivo, Piezo1 knockdown significantly inhibited peritoneal metastasis of GC cells and blocked EMT process and angiogenesis. Our findings suggested that Piezo1 is a key component during GC omentum metastasis, which could be related to up-regulation of HIF-1α.     

CXCL8 modulates human intestinal epithelial cells through a CXCR1 dependent pathway

BACKGROUND: CXCL8 (previously known as Interleukin-8), a member of the alpha-chemokine family of chemotactic cytokines, stimulates intestinal neutrophil activation and chemotaxis. As intestinal epithelial cells have been recently shown to produce CXCL8, the aim of this study was to identify functional activities of CXCL8 on intestinal epithelial cells. METHODS: The expression of CXCL8 receptors CXCR1 and CXCR2 was assessed by RT-PCR and FACS analysis in human Caco-2 and HT-29 cells. The effects of CXCL8 on intestinal epithelial proliferation were assessed with colorimetric MTT assays and the effects on epithelial restitution with an in vitro migration model using Caco-2 and HT-29 cells. RESULTS: While the expression of both CXCR1 mRNA and protein could be demonstrated by RT-PCR and FACS analysis in human Caco-2 and HT-29 cells, no expression of CXCR2 was observed in these cell lines. Colorimetric MTT assays revealed that CXCL8 does not modulate cell proliferation in HT-29 and Caco-2 cells. In contrast, CXCL8 significantly enhanced intestinal epithelial migration in an in vitro migration model of HT-29 and Caco-2 cells. Enhancement of intestinal epithelial cell migration by CXCL8 was partially CXCR1-dependent and TGFbeta-independent. CONCLUSION: CXCL8 exerts functional effects on intestinal epithelial cells that may be relevant for intestinal inflammation and mucosal healing.     

LEM domain containing 1 promotes proliferation via activating the PI3K/Akt signaling pathway in gastric cancer

Gastric cancer (GC) is one of the most common cancers worldwide and has especially high morbidity and mortality in China. LEM domain containing 1 (LEMD1), an important cancer-testis antigen, has been reported to be overexpressed in various cancers and promotes the progression of cancers. However, the biological characteristics of LEMD1 remain to be explored in GC. The connection between LEMD1 expression and GC progression was analyzed by using The Cancer Genome Atlas datasets and our human microarray datasets. A Kaplan-Meier plot was used to analyze the relationship between LEMD1 expression and prognosis. The expression of LEMD1 was analyzed by quantitative real-time polymerase chain reaction and Western blot, and the proliferation ability of GC cells was analyzed by cell proliferation and colony formation assays and 5-ethynyl-2′-deoxyuridine analysis. The cell cycle and apoptosis were analyzed by flow cytometry. Furthermore, subcutaneously implanted tumor models in nude mice were used to demonstrate the role of LEMD1 in promoting tumor proliferation in vivo. In this study, we demonstrated that the LEMD1 expression level was increased in GC tissues and cells compared with normal tissues and GES-1. The in vivo and in vitro assays showed that LEMD1 promoted GC cell proliferation by regulating the cell cycle and apoptosis. Moreover, we showed that LEMD1 regulated cell proliferation by activating the phosphatidylinositol 3 kinase (PI3K) / protein kinase B (AKT) signaling pathway. Overall, the results of our study suggest that LEMD1 contributes to GC proliferation by regulating the cell cycle and apoptosis via activation of the PI3K/AKT signaling pathway. LEMD1 may act as a potential target for GC treatment.     

SDF-1/CXCR4在肿瘤信号转导中作用的分子机制

CXC趋化因子受体4(CXCR4)是最主要的趋化因子受体之一,在多种类型细胞中均有表达,包括淋巴细胞、造血干细胞、内皮细胞和肿瘤细胞。CXCR4与其配体——基质细胞衍生因子1(SDF-1)(也称CXCL12)结合,能介导多种与细胞趋化、细胞存活或增殖相关信号传导通路。CXCR4与SDF-1轴涉及肿瘤的恶性演进、血管生成、转移和存活。因此,阻断CXCR4与SDF-1轴及下游信号通路成为相关治疗的分子靶标。     

CXCL12/CXCR4 transactivates HER2 in lipid rafts of prostate cancer cells and promotes growth of metastatic deposits in bone

Chemokines and their receptors function in migration and homing of cells to target tissues. Recent evidence suggests that cancer cells use a chemokine receptor axis for metastasis formation at secondary sites. Previously, we showed that binding of the chemokine CXCL12 to its receptor CXCR4 mediated signaling events resulting in matrix metalloproteinase-9 expression in prostate cancer bone metastasis. A variety of methods, including lipid raft isolation, stable overexpression of CXCR4, cellular adhesion, invasion assays, and the severe combined immunodeficient-human bone tumor growth model were used. We found that (a) CXCR4 and HER2 coexist in lipid rafts of prostate cancer cells; (b) the CXCL12/CXCR4 axis results in transactivation of the HER2 receptor in lipid rafts of prostate cancer cells; (c) Src kinase mediates CXCL12/CXCR4 transactivation of HER2 in prostate cancer cells; (d) a pan-HER inhibitor desensitizes CXCR4-induced transactivation and subsequent matrix metalloproteinase-9 secretion and invasion; (e) lipid raft-disrupting agents inhibited raft-associated CXCL12/CXCR4 transactivation of the HER2 and cellular invasion; (f) overexpression of CXCR4 in prostate cancer cells leads to increased HER2 phosphorylation and migratory properties of prostate cancer cells; and (g) CXCR4 overexpression enhances bone tumor growth and osteolysis. These data suggest that lipid rafts on the cell membrane are the key site for CXCL12/CXCR4-induced HER2 receptor transactivation. This transactivation contributes to enhanced invasive signals and metastatic growth in the bone microenvironment.     

SNAIL Induces EMT and Lung Metastasis of Tumours Secreting CXCL2 to Promote the Invasion of M2-Type Immunosuppressed Macrophages in Colorectal Cancer

Background: There is increasing evidence that tumour-associated macrophages (TAMs) are critical in the formation of lung metastases. However, the molecular mechanisms of tumour interactions with TAMs via EMT are largely unknown.Methods: The mechanism of lung metastasis was studied in patient tissues. The mechanism of SNAIL regulation of the interaction between mesenchymal cells and M2 macrophages was elucidated using coculture of M2 macrophages and Transwell assays in vitro and in vivo in nude mice and NOD-SCID mice.Results: We demonstrated for the first time that SNAIL and CXCL2 were abnormally overexpressed in colorectal cancer, especially lung metastasis, and were associated with poor prognosis in colorectal cancer patients. We demonstrated that SNAIL promoted the secretion of CXCL2 by mesenchymal cells and induced the activation of M2 macrophages. We found that CXCL2 attracted M2-type macrophages to infiltrate and promote tumour metastasis.Conclusion: These findings suggest that SNAIL promotes epithelial tumour transformation, and that transformed mesenchymal cells secrete CXCL2, which promotes M2 macrophage infiltration and tumour cell metastasis. These findings elucidate the tumour-TAM interaction in the metastatic microenvironment, which is mediated by tumour-derived CXCL2 and affects lung metastasis. This study also provides a theoretical basis for the occurrence of secondary lung cancer.