OBJECTIVE

Anti-tumor immunity changes over the course of tumor progression; it is not clear how or when the developing tumor overcomes immune surveillance. Intraductal papillary mucinous neoplasm (IPMN) is an intraepithelial precursor lesion of pancreatic cancer that progresses from adenoma to carcinoma. We investigated when and how the human anti-tumor immune reaction changes during pancreatic tumor development.

METHODS

Using immunohistochemical analysis of cells isolated from patients with IPMN, the numbers of tumor-infiltrating lymphocytes and dendritic cells and the maturation state of dendritic cells in the regional lymph nodes were investigated during tumor progression. Gene expression profiles were compared among epithelial neoplastic cells at each stage of tumor development. Biological functions of the selected gene products were analyzed using syngeneic mouse models.

RESULTS

The anti-tumor immune reaction changed from an immune response to immune tolerance between the stages of intraductal papillary mucinous adenoma (IPMA) and intraductal papillary mucinous carcinoma (IPMC). Chemokine (C-X-C motif) ligand 17 (CXCL17) and intercellular adhesion molecule 2 (ICAM2) were involved in immune surveillance during tumor development-their expression levels were up-regulated exclusively in IPMA and disappeared from IPMC. CXCL17 and ICAM2 induced infiltration and accumulation of the tumor epithelial layer by immature myeloid dendritic cells. This was followed by a cellular immune reaction and ICAM2 simultaneously promoted the susceptibility of the tumor cells to cytotoxic T-cell-mediated cytolysis. These processes had a synergistic effect to increase the anti-tumor immune response.

CONCLUSIONS

Immune surveillance occurs during the early intraepithelial stages of human pancreatic carcinogenesis and is mediated by expression of CXCL17 and ICAM2.

Chemokines are chemotactic cytokines that direct the traffic of leukocytes and other cells in the body. Chemokines bind to G protein-coupled receptors expressed on target cells to initiate signaling cascades and induce chemotaxis. Although the cognate receptors of most chemokines have been identified, the receptor for the mucosal chemokine CXCL17 is undefined. In this article, we show that GPR35 is the receptor of CXCL17. GPR35 is expressed in mucosal tissues, in CXCL17-responsive monocytes, and in the THP-1 monocytoid cell line. Transfection of GPR35 into Ba/F3 cells rendered them responsive to CXCL17, as measured by calcium-mobilization assays. Furthermore, GPR35 expression is downregulated in the lungs of Cxcl17(-/-) mice, which exhibit defects in macrophage recruitment to the lungs. We conclude that GPR35 is a novel chemokine receptor and suggest that it should be named CXCR8.

The mucosal immune network is a crucial barrier preventing pathogens from entering the body. The network of immune cells that mediates the defensive mechanisms in the mucosa is likely shaped by chemokines, which attract a wide range of immune cells to specific sites of the body. Chemokines have been divided into homeostatic or inflammatory depending upon their expression patterns. Additionally, several chemokines mediate direct killing of invading pathogens, as exemplified by CCL28, a mucosa-associated chemokine that exhibits antimicrobial activity against a range of pathogens. CXCL17 was the last chemokine ligand to be described and is the 17th member of the CXC chemokine family. Its expression pattern in 105 human tissues and cells indicates that CXCL17 is a homeostatic, mucosa-associated chemokine. Its strategic expression in mucosal tissues suggests that it is involved in innate immunity and/or sterility of the mucosa. To test the latter hypothesis, we tested CXCL17 for possible antibacterial activity against a panel of pathogenic and opportunistic bacteria. Our results indicate that CXCL17 has potent antimicrobial activities and that its mechanism of antimicrobial action involves peptide-mediated bacterial membrane disruption. Because CXCL17 is strongly expressed in bronchi, we measured it in bronchoalveolar lavage fluids and observed that it is strongly upregulated in idiopathic pulmonary fibrosis. We conclude that CXCL17 is an antimicrobial mucosal chemokine that may play a role in the pathogenesis of interstitial lung diseases.

BACKGROUND

Chemokines are involved in multiple aspects of pathogenesis and cellular trafficking in tumorigenesis. In this study, we report that the latest member of the C-X-C-type chemokines, CXCL17 (DMC/VCC-1), recruits immature myeloid-derived cells and enhances early tumor progression.

RESULTS

CXCL17 was preferentially expressed in some aggressive types of gastrointestinal, breast, and lung cancer cells. CXCL17 expression did not impart NIH3T3 cells with oncogenic potential in vitro, but CXCL17-expressing NIH3T3 cells could form vasculature-rich tumors in immunodeficient mice. Our data showed that CXCL17-expressing tumor cells increased immature CD11b(+)Gr1(+) myeloid-derived cells at tumor sites in mice and promoted CD31(+) tumor angiogenesis. Extensive chemotactic assays proved that CXCL17-responding cells were CD11b(+)Gr1(high)F4/80(-) cells (≈ 90%) with a neutrophil-like morphology in vitro. Although CXCL17 expression could not increase the number of CD11b(+)Gr1(+) cells in tumor-burdened SCID mice or promote metastases of low metastatic colon cancer cells, the existence of CXCL17-responding myeloid-derived cells caused a striking enhancement of xenograft tumor formation.

CONCLUSIONS

These results suggest that aberrant expression of CXCL17 in tumor cells recruits immature myeloid-derived cells and promotes tumor progression through angiogenesis.

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 CXCL17low group had significantly lower 5-year recurrence rate compared with patients in the CXCL17high 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.

Several chemokines have important functions in mucosal immunity. While there are many chemokines, 4 of them (CCL25, CCL28, CXCL14, and CXCL17) are especially important in mucosal immunity because they are homeostatically expressed in mucosal tissues. Of these, only CCL25 and CCL28 have been widely recognized as mucosal chemokines. In this study, we review the physiology of these chemokines with specific emphasis on their function in mucosal immunity. CCL25 recruits certain important subsets of T cells that express CCR9 to the small intestine. These CCR9+ T cells also express the integrin α4β7 and have been shown to play important roles in the control of intestinal inflammation. CCL28 recruits CCR10+ IgA plasmablasts to the lactating mammary gland. The role of CXCL14 in mucosal immunity is less well defined, but a Cxcl14-/- mouse exhibits significant metabolic abnormalities. Finally, CXCL17 was the last chemokine to be described and signals through a new chemokine receptor (GPR35/CXCR8), which is expressed in a subset of macrophages that are recruited to mucosal tissues by this chemokine. We conclude that these 4 chemokines play very important roles in mucosal immunity and their continued functional characterization will likely identify novel therapeutic targets.

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 G protein-coupled receptor (GPCR) superfamily of integral proteins is the largest family of signal transducers, comprised of ∼1000 members. Considering their prevalence and functional importance, it's not surprising that ∼60% of drugs target GPCRs. Regardless, there exists a subset of the GPCR superfamily that is largely uncharacterized and poorly understood; specifically, more than 140 GPCRs have unknown endogenous ligands-the so-called orphan GPCRs. Orphan GPCRs offer tremendous promise, as they may provide novel therapeutic targets that may be more selective than currently known receptors, resulting in the potential reduction in side effects. In addition, they may provide access to signal transduction pathways currently unknown, allowing for new strategies in drug design. Regardless, orphan GPCRs are an important area of inquiry, as they represent a large gap in our understanding of signal transduction at the cellular level. Here, we focus on the therapeutic potential of two recently deorphanized GPCRs: GPR35/CXCR8 and GPR55. First, GPR35/CXCR8 has been observed in numerous tissues/organ systems, including the gastrointestinal tract, liver, immune system, central nervous system, and cardiovascular system. Not surprisingly, GPR35/CXCR8 has been implicated in numerous pathologies involving these tissues/systems. While several endogenous ligands have been identified, GPR35/CXCR8 has recently been observed to bind the chemokine CXCL17. Second, GPR55 has been observed to be expressed in the central nervous system, adrenal glands, gastrointestinal tract, lung, liver, uterus, bladder, kidney, and bone, as well as, other tissues/organ systems. Likewise, it is not surprising that GPR55 has been implicated in pathologies involving these tissues/systems. GPR55 was initially deorphanized as a cannabinoid receptor and this receptor does bind many cannabinoid compounds. However, the GPR55 endogenous ligand has been found to be a non-cannabinoid, lysophophatidylinositol (LPI) and subsequent high throughput assays have identified other GPR55 ligands that are not cannabinoids and do not bind to either the cannabinoid CB1 and CB2 receptors. Here, we review reports that suggest that GPR35/CXCR8 and GPR55 may be promising therapeutic targets, with diverse physiological roles.

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.

BACKGROUND

The novel chemokine CXCL17 acts as chemoattractant for monocytes, macrophages and dendritic cells. CXCL17 also has a role in angiogenesis of importance for tumour development.

METHODS

Expression of CXCL17, CXCL10, CXCL9 and CCL2 was assessed in primary colon cancer tumours, colon carcinoma cell lines and normal colon tissue at mRNA and protein levels by real-time qRT-PCR, immunohistochemistry, two-colour immunofluorescence and immunomorphometry.

RESULTS

CXCL17 mRNA was expressed at 8000 times higher levels in primary tumours than in normal colon (P < 0.0001). CXCL17 protein was seen in 17.2% of cells in tumours as compared with 0.07% in normal colon (P = 0.0002). CXCL10, CXCL9 and CCL2 mRNAs were elevated in tumours but did not reach the levels of CXCL17. CXCL17 and CCL2 mRNA levels were significantly correlated in tumours. Concordant with the mRNA results, CXCL10- and CXCL9-positive cells were detected in tumour tissue, but at significantly lower numbers than CXCL17. Two-colour immunofluorescence and single-colour staining of consecutive sections for CXCL17 and the epithelial cell markers carcinoembryonic antigen and BerEP4 demonstrated that colon carcinoma tumour cells indeed expressed CXCL17.

CONCLUSIONS

CXCL17 is ectopically expressed in primary colon cancer tumours. As CXCL17 enhances angiogenesis and attracts immune cells, its expression could be informative for prognosis in colon cancer patients.

Chemokines play pivotal roles in the recruitment of various immune cells to diverse tissues in both physiological and pathological conditions. CXCL17 is an orphan chemokine preliminarily found to be involved in tumor angiogenesis. However, its protein nature, as well as its endogenous bioactivity, has not been well clarified. Using real-time PCR, immunohistochemical staining, and Western blotting, we found that CXCL17 is highly expressed in both a constitutive and inducible manner in the rat gastric mucosa, where it undergoes endoproteolysis during protein maturation. The mature CXCL17 exhibited strong chemoattractant abilities targeting monocytes and macrophages, potentially through ERK1/2 and p38 but not JNK signaling. CXCL17 also induced the production of proangiogenic factors such as vascular endothelial growth factor A from treated monocytes. Furthermore, in contrast to other CXC chemokines that accelerate inflammatory responses, CXCL17 showed novel anti-inflammatory effects on LPS-activated macrophages. Therefore, our data suggest that CXCL17 in the gastric lamina propria may play an important role in tissue repair and anti-inflammation, both of which help to maintain the integrity of the gastric mucosa.

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.

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.

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.

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.

GPR35 has long been considered an orphan GPCR, because no endogenous ligand of GPR35 has been discovered. CXCL17 (a chemokine) has been reported to be an endogenous ligand of GPR35, and it has even been suggested that it be called CXCR8. However, at present there is no supporting evidence that CXCL17 does interact with GPR35.

We applied two assay systems to explore the relationship between CXCL17 and GPR35. An AP-TGF-α shedding assay in GPR35 over-expressing HEK293 cells was used as a gain-of-function assay. GPR35 knock-down by siRNA transfection was performed in endogenously GPR35-expressing THP-1 cells.

In the AP-TGF-α shedding assay, lodoxamide, a well-known synthetic GPR35 agonist, was confirmed to be the most potent agonist among other reported agonists. However, neither human nor mouse CXCL17 had an effect on GPR35. Consistent with previous findings, G proteins Gαi/o and Gα12/13 were found to couple with GPR35. Furthermore, lodoxamide-induced activation of GPR35 was concentration-dependently inhibited by CID2745687 (a selective GPR35 antagonist). In endogenously GPR35-expressing THP-1 cells, lodoxamide concentration-dependently inhibited migration and this inhibitory effect was blocked by CID2745687 treatment or GPR35 siRNA transfection. However, even though CXCL17 stimulated the migration of THP-1 cells, which is consistent with a previous report, this stimulatory effect of CXCL17 was not blocked by CID2745687 or GPR35 siRNA.

The present findings suggest that GPR35 functions as a migration inhibitory receptor, but CXCL17-stimulated migration of THP-1 cells is not dependent on GPR35.

The chemokine CXCL17 is associated with the innate response in mucosal tissues but is poorly characterized. Similarly, the G protein-coupled receptor GPR35, expressed by monocytes and mast cells, has been implicated in the immune response, although its precise role is ill-defined. A recent manuscript reported that GPR35 was able to signal in response to CXCL17, which we set out to confirm in this study. GPR35 was readily expressed using transfection systems but failed to signal in response to CXCL17 in assays of β-arrestin recruitment, inositol phosphate production, calcium flux, and receptor endocytosis. Similarly, in chemotaxis assays, GPR35 did not confirm sensitivity to a range of CXCL17 concentrations above that observed in the parental cell line. We subsequently employed a real time chemotaxis assay (TAXIScan) to investigate the migratory responses of human monocytes and the monocytic cell line THP-1 to a gradient of CXCL17. Freshly isolated human monocytes displayed no obvious migration to CXCL17. Resting THP-1 cells showed a trend toward directional migration along a CXCL17 gradient, which was significantly enhanced by overnight incubation with PGE2 However, pretreatment of PGE2-treated THP-1 cells with the well-characterized GPR35 antagonist ML145 did not significantly impair their migratory responses to CXCL17 gradient. CXCL17 was susceptible to cleavage with chymase, although this had little effect its ability to recruit THP-1 cells. We therefore conclude that GPR35 is unlikely to be a bona fide receptor for CXCL17 and that THP-1 cells express an as yet unidentified receptor for CXCL17.

During acute inflammation, functioning lymphatics are believed to reduce edema and to provide a transiting route for immune cells, but the extent at which the dermal lymphatic remodeling impacts lymphatic transport or the factors regulating these changes remains unclear. Herein we quantify the increase in lymphatic endothelial cells (LECs) and examine the expression of pro-angiogenenic and lymphangiogenic factors during acute cutaneous hypersensitivity (CHS). We found that LECs actively proliferate during CHS but that this proliferation does not affect the lymphatic vessel density. Instead, lymphatic remodeling is accompanied by lymphatic vessel leakiness and lower ejection of lymph fluid, which is observed only in the proximal lymphatic vessel draining the inflamed area. LECs and the immune cells release growth factors and cytokines during inflammation, which impact the lymphatic microenvironment and function. We identified that FGF-2, PLGF-2, HGF, EGF, and KC/CXCL17 are differentially expressed within tissues during acute CHS, but both VEGF-C and VEGF-D levels do not significantly change. Our results indicate that VEGF-C and VEGF-D are not the only players and other factors may be responsible for the LECs proliferation and altered lymphatic function in acute CHS.

Squamous cell carcinoma (SCC) of horn is frequently observed in Bos indicus affecting 1% of cattle population and accounting 83.34% of total tumours found. The transcriptome profile of horn cancer (HC) tissue and the matched normal (HN) tissue were analysed by RNA-seq using Roche 454 sequencing. A total of 1 504 900 reads comprising of 612 MB data were used to identify differentially expressed genes using CLC Genomic Workbench. These include up-regulation of KRT6A, KRT6B, KRT6C, KRT14, SFN, KRT84, PI3, COL17A1, ANLN, SERPINB5 and down-regulation of BOLA, SCGB1A1, CXCL17, KRT19, BPIFB1, NR4A1 and TFF3 in HC, which are involved in regulation of gene transcription, cell proliferation, apoptosis, cell survival and metabolic pathways. The qPCR analysis of several targets suggested concordance of gene expression profile with RNA-seq analysis. The present findings would provide basis for further screening of genes and identification of markers for early diagnosis and therapeutic intervention of HC.

BACKGROUND

Malignant transformation of type I endometrium involves alteration in gene expression with subsequent uncontrolled proliferation of altered cells.

OBJECTIVE

The main objective of the present study was to identify the cancer-related genes and gene pathways in the endometrium of healthy and cancer patients.

METHODS

Thirty endometrial tissues from healthy and type I EC patients were subjected to total RNA isolation. The RNA samples with good integrity number were hybridized to a new version of Affymetrix Human Genome GeneChip 1.0 ST array. We analyzed the results using the GeneSpring 9.0 GX and the Pathway Studio 6.1 software. For validation assay, quantitative real-time polymerase chain reaction was used to analyze 4 selected genes in normal and EC tissue.

RESULTS

Of the 28,869 genes profiled, we identified 621 differentially expressed genes (2-fold) in the normal tissue and the tumor. Among these genes, 146 were up-regulated and 476 were down-regulated in the tumor as compared with the normal tissue (P < 0.001). Up-regulated genes included the v-erb-a erythroblastic leukemia viral oncogene homolog 3 (ErbB3), ErbB4, E74-like factor 3 (ELF3), and chemokine ligand 17 (CXCL17). The down-regulated genes included signal transducer and activator transcription 5B (STAT5b), transforming growth factor A receptor III (TGFA3), caveolin 1 (CAV1), and protein kinase C alpha (PKCA). The gene set enrichment analysis showed 10 significant gene sets with related genes (P < 0.05). The quantitative polymerase chain reaction of 4 selected genes using similar RNA confirmed the microarray results (P < 0.05).

CONCLUSIONS

Identification of molecular pathways with their genes related to type I EC contribute to the understanding of pathophysiology of this cancer, probably leading to identifying potential biomarkers of the cancer.

The utility of mRNA and protein determinations of G protein-coupled receptor 35, that is, GPR35a (GPR35 V1) and GPR35b (GPR35 V2/3), as indicators of outcome for colon cancer patients after curative surgery was investigated. Expression levels of V1 and V2/3 GPR35, carcinoembryonic antigen and CXCL17 mRNAs were assessed in primary tumours and regional lymph nodes of 121 colon cancer patients (stage I-IV), colon cancer cell lines and control colon epithelial cells using real-time quantitative reverse transcriptase-polymerase chain reaction. Expression of G protein-coupled receptor 35 was investigated by two-colour immunohistochemistry and immunomorphometry. GPR35 V2/3 mRNA, but not V1 mRNA, was expressed in colon cancer cell lines, primary colon tumours and control colon epithelial cells. Haematoxylin and eosin positive (H&E(+)), but not H&E(-), lymph nodes expressed high levels of GPR35 V2/3 mRNA (P<0.0001). GPR35b and carcinoembryonic antigen proteins were simultaneously expressed in many colon cancer tumour cells. Kaplan-Meier and hazard ratio analysis revealed that patients with lymph nodes expressing high levels of GPR35 V2/3 mRNA and, in particular, in the group of patients with lymph nodes also expressing carcinoembryonic antigen mRNA, had a short disease-free survival time, 67 months versus 122 months at 12-year follow-up (difference: 55 months, P = 0.001; hazard ratio: 3.6, P = 0.002). In conclusion, high level expression of G protein-coupled receptor 35 V2/3 mRNA in regional lymph nodes of colon cancer patients is a sign of poor prognosis.

B7-H4, an immune suppressive member of the B7 family, is highly expressed in a wide variety of human malignancies making it an attractive immunotherapeutic target. However, the association between B7-H4 expression in the tumor microenvironment and the immune infiltrate has not been comprehensively examined. To evaluate the immune tumor microenvironment, we analyzed epithelial ovarian tumors from 28 patients using flow cytometry, immunohistochemistry, functional, and genomic analyses. We determined B7-H4 expression patterns and compared the immune infiltrates of tumors with high and low surface expression of B7-H4. Frequencies and phenotypes of tumor and immune cells were determined using multiple flow cytometry panels. Immunohistochemistry was used to analyze cellular infiltration and location. Publicly available datasets were interrogated to determine intratumoral cytokine and chemokine expression. We found that B7-H4 was predominantly expressed by tumor cells in the epithelial ovarian tumor microenvironment. Surface expression of B7-H4 on tumor cells was correlated with higher levels of infiltrating mature antigen-presenting cells. Further, expression of CXCL17, a monocyte and dendritic cell chemoattractant, correlated strongly with B7-H4 expression. T cells expressed activation markers, but T cells expressing a combination of markers associated with T cell activation/exhaustion phenotype were not prevalent. Overall, our data suggest that B7-H4 is associated with a pro-inflammatory tumor microenvironment.

Hypoxia is an integral component of the tumor microenvironment. Either as chronic or cycling hypoxia, it exerts a similar effect on cancer processes by activating hypoxia-inducible factor-1 (HIF-1) and nuclear factor (NF-κB), with cycling hypoxia showing a stronger proinflammatory influence. One of the systems affected by hypoxia is the CXC chemokine system. This paper reviews all available information on hypoxia-induced changes in the expression of all CXC chemokines (CXCL1, CXCL2, CXCL3, CXCL4, CXCL5, CXCL6, CXCL7, CXCL8 (IL-8), CXCL9, CXCL10, CXCL11, CXCL12 (SDF-1), CXCL13, CXCL14, CXCL15, CXCL16, CXCL17) as well as CXC chemokine receptors-CXCR1, CXCR2, CXCR3, CXCR4, CXCR5, CXCR6, CXCR7 and CXCR8. First, we present basic information on the effect of these chemoattractant cytokines on cancer processes. We then discuss the effect of hypoxia-induced changes on CXC chemokine expression on the angiogenesis, lymphangiogenesis and recruitment of various cells to the tumor niche, including myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), regulatory T cells (T_regs) and tumor-infiltrating lymphocytes (TILs). Finally, the review summarizes data on the use of drugs targeting the CXC chemokine system in cancer therapies.

Keywords: CXC chemokine; HIF-1α; IL-8; NF-κB; SDF-1; cancer; cycling hypoxia; hypoxia; hypoxia-inducible factor; tumor.

Background: Hepatocellular carcinoma (HCC) cells-secreted exosomes (exo) could stimulate M2 macrophage polarization and promote HCC progression, but the related mechanism of long non-coding RNA distal-less homeobox 6 antisense 1 (DLX6-AS1) with HCC-exo-mediated M2 macrophage polarization is largely ambiguous. Thereafter, this research was started to unearth the role of DLX6-AS1 in HCC-exo in HCC through M2 macrophage polarization and microRNA (miR)-15a-5p/C-X-C motif chemokine ligand 17 (CXCL17) axis.

Methods: DLX6-AS1, miR-15a-5p and CXCL17 expression in HCC tissues and cells were tested. Exosomes were isolated from HCC cells with overexpressed DLX6-AS1 and co-cultured with M2 macrophages. MiR-15a-5p/CXCL17 down-regulation assays were performed in macrophages. The treated M2 macrophages were co-cultured with HCC cells, after which cell migration, invasion and epithelial mesenchymal transition were examined. The targeting relationships between DLX6-AS1 and miR-15a-5p, and between miR-15a-5p and CXCL17 were explored. In vivo experiment was conducted to detect the effect of exosomal DLX6-AS1-induced M2 macrophage polarization on HCC metastasis.

Results: Promoted DLX6-AS1 and CXCL17 and reduced miR-15a-5p exhibited in HCC. HCC-exo induced M2 macrophage polarization to accelerate migration, invasion and epithelial mesenchymal transition in HCC, which was further enhanced by up-regulated DLX6-AS1 but impaired by silenced DLX6-AS1. Inhibition of miR-15a-5p promoted M2 macrophage polarization to stimulate the invasion and metastasis of HCC while that of CXCL17 had the opposite effects. DLX6-AS1 mediated miR-15a-5p to target CXCL17. DLX6-AS1 from HCC-exo promoted metastasis in the lung by inducing M2 macrophage polarization in vivo.

Conclusion: DLX6-AS1 from HCC-exo regulates CXCL17 by competitively binding to miR-15a-5p to induce M2 macrophage polarization, thus promoting HCC migration, invasion and EMT.

Keywords: C-X-C motif chemokine ligand 17; Hepatocellular carcinoma; Hepatocellular carcinoma cell-secreted exosomes; Long non-coding RNA distal-less homeobox 6 antisense 1; M2 macrophages; microRNA-15a-5p.

OBJECTIVE

The aim of this study was to analyze the gene expression profile and biological processes enriched in gastric cancer.

METHODS

We collected five human advanced gastric cancer tissues by gastroscopy and five peritumor normal tissues as controls and examined the gene expression changes by microarray. KEGG Orthology Based Annotation System annotation was used to identify pathways and biological processes regulated by the deregulated genes. Protein-protein interaction network analysis identified protein complex and functional modules. We also selected 14 genes for further verification by real-time quantitative Polymerase Chain Reaction (PCR).

RESULTS

Human gene expression profile analysis showed that 2028 deregulated genes were detected in gastric cancer compared with the control group (at least a 2.0-fold change and P < 0.05), among which there were 689 upregulated and 1339 downregulated genes. Interestingly, we identified some important genes, such as CXCL17, OTX1 and CCDC125, which have not previously been reported in gastric cancer. Real-time quantitative PCR results verified that CXCL8, OTX1, CEBPB, FOSL1, FOXS1, ARFRP1 and IRF9 were upregulated in gastric cancer and CCDC125, PPP1R36, SOX2, JUN and MIA2 were downregulated. Moreover, bioinformatics analysis demonstrated that the biological processes of inflammatory response, angiogenesis, cell migration and pathways of chemokine signaling pathway, TNF signaling pathway were enriched. We also selected the top 30 significant Gene Ontology terms and select pathways for a brief summary.

CONCLUSIONS

We performed a global analysis of the mRNA landscape in gastric cancer. Our results may stimulate a deeper understanding of the disease, and lead to the development of potential therapies and the identification of novel biomarkers.