Differential expression patterns of CXCR3 variants and corresponding CXC chemokines in clear cell ovarian cancers and endometriosis

The Role of CXCL11 and its Receptors in Cancer: Prospective but Challenging Clinical Targets

Chemokine ligand 11 is a member of the CXC chemokine family and exerts its biological function mainly through binding to CXCR3 and CXCR7. The CXCL11 gene is ubiquitously overexpressed in various human malignant tumors; however, its specific mechanisms vary among different cancer types. Recent studies have found that CXCL11 is involved in the activation of multiple oncogenic signaling pathways and is closely related to tumorigenesis, progression, chemotherapy tolerance, immunotherapy efficacy, and poor prognosis. Depending on the specific expression of its receptor subtype, CXCL11 also has a complex 2-fold role in tumours; therefore, directly targeting the structure-function of CXCL11 and its receptors may be a challenging task. In this review, we summarize the biological functions of CXCL11 and its receptors and their roles in various types of malignant tumors and point out the directions for clinical applications.

Relationship between Plasma IP-10/CXCL10 Levels and the Initial Therapeutic Response in Patients Treated with Atezolizumab plus Bevacizumab for Unresectable Hepatocellular Carcinoma

INTRODUCTION

Atezolizumab plus bevacizumab combination therapy (AB) was the first-line treatment for unresectable hepatocellular carcinoma (u-HCC). IFN-γ-induced protein 10 (IP-10/CXCL10) is a chemokine to inhibit HCC proliferation by promoting the migration of cytotoxic T cells. We focused on the relationship between plasma IP-10/CXCL10 levels and the initial therapeutic response in patients receiving AB therapy.

METHODS

Forty-six patients receiving AB therapy were enrolled. Plasma IP-10/CXCL10 levels were measured at baseline, 3-7 days, 3 weeks, 6 weeks, and 8-12 weeks after the start of AB therapy. The initial therapeutic response was evaluated at 8-12 weeks.

RESULTS

The baseline IP-10/CXCL10 levels of partial response (PR) group was higher than that of stable disease (SD) or progressive disease (PD) group. Patients with the baseline IP-10/CXCL10 of 84 pg/mL or higher were likely to present PR than patients below (71 vs. 35%, p = 0.031), but prediction of PD using the baseline IP-10/CXCL10 levels was difficult. In contrast, IP-10/CXCL10 ratio of the PR group was lower than that of the SD/PD group at 3, 6, and 8-12 weeks. Patients with the 3, 6, and 8-12 weeks IP-10/CXCL10 ratio of 1.3, 0.4, and 0.4 or lower were likely to present PR than patients with ≥1.3, 0.4, and 0.4 (88, 35, 35 vs. 30, 3.8, 0%, p < 0.001, 0.011, 0.002). In other hand, the 3, 6, and 8-12 weeks IP-10/CXCL10 ratio for PD group was higher than that for non-PD group. Patients with the 3, 6, and 8-12 weeks IP-10/CXCL10 ratio of 1.3, 1.7, and 1.9 or higher were likely to present PD than patients below (85, 62, 57 vs. 32, 23, 14%, p = 0.002, 0.034, 0.009).

CONCLUSION

High baseline IP-10/CXCL10 levels may be associated with better outcome, and high IP-10/CXCL10 ratio after 3-12 weeks may be associated with worse outcome in u-HCC patients receiving AB therapy.

CXC chemokines influence immune surveillance in immunological disorders: Polycystic ovary syndrome and endometriosis

Reproductive health is a worldwide challenge, but it is of particular significance to women during their reproductive age. Several female reproductive problems, including polycystic ovary syndrome (PCOS) and endometriosis, affect about 10 % of women and have a negative impact on their health, fertility, and quality of life. Small, chemotactic, and secreted cytokines are CXC chemokines. Both PCOS and endometriosis demonstrate dysregulation of CXC chemokines, which are critical to the development and progression of both diseases. Recent research has shown that both in humans and animals, CXC chemokines tend to cause inflammation. It has also been found that CXC chemokines are necessary for promoting angiogenesis and inflammatory responses. CXC chemokine overexpression is frequently associated with poor survival and prognosis. CXC chemokine levels in PCOS and endometriosis patients impact their circumstances significantly. Hence, CXC chemokines have significant potential as diagnostic and prognostic biomarkers and therapeutic targets. The molecular mechanisms through which CXC chemokines promote inflammation and the development of PCOS and endometriosis are currently unknown. This article will discuss the functions of CXC chemokines in the promotion, development, and therapy of PCOS and endometriosis, as well as future research directions. The current state and future prospects of CXC chemokine -based therapeutic strategies in the management of PCOS and endometriosis are also highlighted.

Interferon-γ-Inducible Chemokines as Prognostic Markers for Lung Cancer

Interferon (IFN)-γ-inducible chemokines in the CXCR3/ligand axis are involved in cell-mediated immunity and play a significant role in the progression of cancer. We enrolled patients with lung cancer (n = 144) and healthy volunteers as the controls (n = 140). Initial blood samples were collected and concentrations of IFN-γ and IFN-γ-inducible chemokines CXCL9, CXCL10, and CXCL11 were measured using enzyme-linked immunosorbent assay. Of patients with lung cancer, 125 had non-small cell lung cancer (NSCLC) and 19 had small cell lung cancer. The area under the curve (AUC) (95% CI) of CXCL9 was 0.83 (0.80-0.89) for differentiating lung cancer patients from controls. The levels of all the markers were significantly higher in NSCLC patients with stage IV than in those with stages I-III. A Kaplan-Meier survival analysis showed that NSCLC cancer patients with higher levels of all markers showed poorer survival than those with lower levels. In Cox multivariate analysis of patients with NSCLC, independent prognostic factors for overall survival were CXCL9 and CXCL11. CXCL9 was the only independent prognostic factor for cancer-specific survival. Serum IFN-γ-inducible chemokines may be useful as clinical markers of metastasis and prognosis in NSCLC, and CXCL9 levels showed the most significant results.

CXCR3 Expression and Genome-Wide 3' Splice Site Selection in the TCGA Breast Cancer Cohort

CXCR3 is a chemokine receptor with two well-characterized isoforms that have unique, context-dependent roles: CXCR3-A and CXCR3-B, which are produced through alternative 3′ splice site selection (A3SS). RNA-seq data from The Cancer Genome Atlas (TCGA) were used to correlate CXCR3 expression with breast cancer progression. This analysis revealed significant CXCR3 expression patterns associated with survival and differential expression between the tumor and adjacent normal tissue. TCGA data were used to estimate abundance of immune cells in breast cancer, which demonstrated the association of CXCR3 with immune infiltration, particularly in the triple-negative subtype. Given the importance of A3SS in CXCR3, genome-wide analysis of A3SS events was performed to identify events that were differentially spliced between breast cancer tissue and adjacent normal tissue. A total of 481 splicing events in 424 genes were found to be differentially spliced. The parent genes of differentially spliced events were enriched in RNA processing and splicing functions, indicating an underappreciated role of A3SS in the integrated splicing network of breast cancer. These results further validated the role of CXCR3 in immune infiltration of tumors, while raising questions about the role of A3SS splicing.

Immunologic factors involved in the malignant transformation of endometriosis to endometriosis-associated ovarian carcinoma

INTRODUCTION

Endometriosis is a risk factor for low-grade serous, clear cell, and endometroid ovarian carcinoma. In both endometriosis and ovarian carcinoma, immunological factors are associated with clinical outcome. Chronic inflammation in endometriosis may be linked to tumorigenesis, but exact processes contributing to endometriosis-associated ovarian carcinoma remain unknown. This review aims to describe potential immunological factors involved in the malignant transformation of endometriosis into ovarian carcinoma.

METHODS

PubMed and Embase were searched from inception up to October 2020 for studies comparing immunological processes in endometriosis and endometriosis-associated ovarian carcinoma.

RESULTS

Detailed analysis of immune components in the malignant transformation of endometriosis into endometriosis-associated ovarian carcinoma is lacking. Altered levels of chemokines and cytokines as IL-6, IL-8, IL-10, and TNF-α are reported and the function, number and polarization of NK cells, dendritic cells, and monocytes differ between endometriosis and associated ovarian carcinoma compared to healthy tissue. In addition, altered inflammasome and complement systems, indicate a role for the immune system in the carcinogenesis of endometriosis.

CONCLUSION

Chronic inflammation in endometriosis may potentially drive inflammation-induced carcinogenesis in endometriosis-associated ovarian carcinoma. Exact immunological pathways and cellular processes remain unknown and require more thorough investigation.

The Distinct Roles of CXCR3 Variants and Their Ligands in the Tumor Microenvironment

First thought to orchestrate exclusively leukocyte trafficking, chemokines are now acknowledged for their multiple roles in the regulation of cell proliferation, differentiation, and survival. Dysregulation of their normal functions contributes to various pathologies, including inflammatory diseases and cancer. The two chemokine receptor 3 variants CXCR3-A and CXCR3-B, together with their cognate chemokines (CXCL11, CXCL10, CXCL9, CXCL4, and CXCL4L1), are involved in the control but also in the development of many tumors. CXCR3-A drives the infiltration of leukocytes to the tumor bed to modulate tumor progression (paracrine axis). Conversely, tumor-driven changes in the expression of the CXCR3 variants and their ligands promote cancer progression (autocrine axis). This review summarizes the anti- and pro-tumoral activities of the CXCR3 variants and their associated chemokines with a focus on the understanding of their distinct biological roles in the tumor microenvironment.

Overview of the Mechanisms that May Contribute to the Non-Redundant Activities of Interferon-Inducible CXC Chemokine Receptor 3 Ligands

The inflammatory chemokines CXCL9, CXCL10, and CXCL11 are predominantly induced by interferon (IFN)-γ and share an exclusive chemokine receptor named CXC chemokine receptor 3 (CXCR3). With a prototype function of directing temporal and spatial migration of activated T cells and natural killer cells, and inhibitory effects on angiogenesis, these CXCR3 ligands have been implicated in infection, acute inflammation, autoinflammation and autoimmunity, as well as in cancer. Intense former research efforts led to recent and ongoing clinical trials using CXCR3 and CXCR3 ligand targeting molecules. Scientific evidence has claimed mutual redundancy, ligand dominance, collaboration or even antagonism, depending on the (patho)physiological context. Most research on their in vivo activity, however, illustrates that CXCL9, CXCL10, and CXCL11 each contribute to the activation and trafficking of CXCR3 expressing cells in a non-redundant manner. When looking into detail, one can unravel a multistep machinery behind final CXCR3 ligand functions. Not only can specific cell types secrete individual CXCR3 interacting chemokines in response to certain stimuli, but also the receptor and glycosaminoglycan interactions, major associated intracellular pathways and susceptibility to processing by particular enzymes, among others, seem ligand-specific. Here, we overview major aspects of the molecular properties and regulatory mechanisms of IFN-induced CXCR3 ligands, and propose that their in vivo non-redundancy is a reflection of the unprecedented degree of versatility that seems inherent to the IFN-related CXCR3 chemokine system.

Differential expression profile of CXCR3 splicing variants is associated with thyroid neoplasia. Potential role in papillary thyroid carcinoma oncogenesis?

Papillary thyroid cancer (PTC) is the most prevalent endocrine neoplasia. The increased incidence of PTC in patients with thyroiditis and the frequent immune infiltrate found in PTC suggest that inflammation might be a risk factor for PTC development. The CXCR3-ligand system is involved in thyroid inflammation and CXCR3 has been found upregulated in many tumors, suggesting its pro-tumorigenic role under the inflammatory microenvironment. CXCR3 ligands (CXCL4, CXCL9, CXCL10 and CXCL11) trigger antagonistic responses partly due to the presence of two splice variants, CXCR3A and CXCR3B. Whereas CXCR3A promotes cell proliferation, CXCR3B induces apoptosis. However, the relation between CXCR3 variant expression with chronic inflammation and PTC development remains unknown. Here, we characterized the expression pattern of CXCR3 variants and their ligands in benign tumors and PTC. We found that CXCR3A and CXCL10 mRNA levels were increased in non-metastatic PTC when compared to non-neoplastic tissue. This increment was also observed in a PTC epithelial cell line (TPC-1). Although elevated protein levels of both isoforms were detected in benign and malignant tumors, the CXCR3A expression remained greater than CXCR3B and promoted proliferation in Nthy-ori-3-1 cells. In non-metastatic PTC, inflammation was conditioning for the CXCR3 ligands increased availability. Consistently, CXCL10 was strongly induced by interferon gamma in normal and tumor thyrocytes.

Our results suggest that persistent inflammation upregulates CXCL10 expression favoring tumor development via enhanced CXCR3A-CXCL10 signaling. These findings may help to further understand the contribution of inflammation as a risk factor in PTC development and set the basis for potential therapeutic studies.

CXCR3 mediates ascites-directed tumor cell migration and predicts poor outcome in ovarian cancer patients

Intraabdominal tumor dissemination is a major hallmark of epithelial ovarian cancer (EOC), but the underlying mechanisms have not been fully elucidated. The CXCR3 chemokine receptor supports migration of tumor cells to metastatic sites, but its role in ovarian cancer metastasis is largely unknown. Herein, we first screened two independent cohorts of high-grade serous ovarian cancers (HGSCs, discovery set n=60, validation set n=117) and 102 metastatic lesions for CXCR3 expression. In primary tumors, CXCR3 was particularly overexpressed by tumor cells at the invasive front. In intraabdominal metastases, tumor cells revealed a strong CXCR3 expression regardless of its expression in the corresponding primary tumor, suggesting a selection of CXCR3-overexpressing cancer cells into peritoneal niches. In support of this, CXCR3 mediated the migration of tumor cell lines OVCAR3 and SKOV3 toward malignant ascites, which was inhibited by a monoclonal anti-CXCR3 antibody in vitro. These results were prospectively validated in ascites-derived tumor cells from EOC patients ex vivo (n=9). Moreover, tumor cell-associated overexpression of CXCR3 in advanced ovarian cancer patients was associated with a reduced progression-free survival (PFS) and overall survival (OS), which remained independent of optimal debulking, age, FIGO stage and lymph node involvement (PFS: hazard ratio (HR) 2.11, 95% confidence interval (CI) 1.30–3.45, P=0.003; OS: HR 2.36, 95% CI 1.50–3.71, P<0.001). These results in ovarian cancer patients identify CXCR3 as a potential new target to confine peritoneal spread in ovarian cancer after primary cytoreductive surgery.

Chemokine receptor CXCR3 deficiency exacerbates murine autoimmune cholangitis by promoting pathogenic CD8+ T cell activation

CXC Chemokine Receptor 3 (CXCR3) is functionally pleiotropic and not only plays an important role in chemotaxis, but also participates in T cell differentiation and may play a critical role in inducing and maintaining immune tolerance. These observations are particularly critical for autoimmune cholangitis in which CXCR3 positive T cells are found around the portal areas of both humans and mouse models of primary biliary cholangitis (PBC). Herein, we investigated the role of CXCR3 in the pathogenesis of autoimmune cholangitis. We have taken advantage of a unique CXCR3 knockout dnTGFβRII mouse to focus on the role of CXCR3, both by direct observation of its influence on the natural course of disease, as well as through adoptive transfer studies into Rag-/- mice. We report herein that not only do CXCR3 deficient mice develop an exacerbation of autoimmune cholangitis associated with an expanded effector memory T cell number, but also selective adoptive transfer of CXCR3 deficient CD8⁺ T cells induces autoimmune cholangitis. In addition, gene microarray analysis of CXCR3 deficient CD8⁺ T cells reveal an intense pro-inflammatory profile. Our data suggests that the altered gene profiles induced by CXCR3 deficiency promotes autoimmune cholangitis through pathogenic CD8⁺ T cells. These data have significance for human PBC and other autoimmune liver diseases in which therapeutic intervention might be directed to chemokines and/or their receptors.

CXCR3A contributes to the invasion and metastasis of gastric cancer cells

CXCR3, belonging to CXC chemokine receptors, has been identified to be overexpressed in various kinds of tumors. There are three mRNA variants of CXCR3 (CXCR3A, CXCR3B and CXCR3alt) in human cells. The functions of major CXCR3 isoforms (CXCR3A, CXCR3B) have been reported in some tumors including prostate and breast cancer. However, the effects of CXCR3A and CXCR3B on gastric cancer cell progression remain unknown. The present investigation found that CXCR3A mRNA level was upregulated but CXCR3B mRNA level was downregulated in gastric cancer cells and tissues. In vitro growth analysis showed that CXCR3A acted as a positive mediator in regulating cell growth, whereas CXCR3B exerted the opposite effect. In vitro invasion and migration assays showed that CXCL10 promoted gastric cancer cell invasion and migration via CXCR3A, but not CXCR3B. Moreover, knockdown of CXCR3A inhibited cell growth and metastasis in vivo. Additionally, CXCR3A knockdown attenuated matrix metalloproteinase (MMP)‑13 and IL‑6 expression, and reduced ERK1/2 activation. Together, these data suggest that CXCR3A contributes to the growth, invasion and metastasis of gastric cancer cells in vitro and in vivo, and thus may be a key mediator of gastric cancer progression.

Overexpression of the chemokine receptor CXCR3 and its correlation with favorable prognosis in gastric cancer

Chemokine receptor, CXCR3, has been increasingly reported to be involved in tumorigenesis and tumor progression, but limited data are available regarding the expression of CXCR3 in gastric cancer (GC). In the present study, the expressions of CXCR3 and its variants were detected in 96 GC and corresponding nontumor gastric tissues by immunohistochemical staining, in 40 freshly frozen GC and nontumor gastric tissues by reverse-transcription polymerase chain reaction and quantitative real-time polymerase chain reaction, and in 10 freshly frozen GC and nontumor gastric tissues by Western blotting. Results revealed that an overexpression of CXCR3 occurs in GC tissues as compared to the nontumor gastric tissues. High level of CXCR3 expression was found to be inversely associated with invasion depth and metastasis (P = .030 and P = .019, respectively) and directly associated with improved overall survival (log-rank test, P < .001). Furthermore, multivariate analysis showed that high CXCR3 expression acts an independent prognostic factor for GC patients (hazard ratio, 0.379 [0.196-0.734]; P = .004). The messenger RNA expression of both the CXCR3 variants, CXCR3-A and CXCR3-B, were up-regulated in GC tissues (P = .006 and P = .002, respectively), although CXCR3-B messenger RNA expression was significantly higher than CXCR3-A, with an average CXCR3-B to CXCR3-A ratio of 1.80. CXCR3-B protein expression was also up-regulated in GC tissues (P = .023). In conclusion, our study suggested a potential use of CXCR3 overexpression as a prognostic marker for GC and involvement of the up-regulation of CXCR3-B in favorable prognosis of GC patients.

CXCR3 Polymorphism and Expression Associate with Spontaneous Preterm Birth

Spontaneous preterm birth (SPTB) is a major factor associating with deaths and with lowered quality of life in humans. Environmental and genetic factors influence the susceptibility. Previously, by analyzing families with recurrent SPTB in linkage analysis, we identified a linkage peak close to the gene encoding CXCR3. Present objectives were to investigate the association of CXCR3 with SPTB in Finnish mothers (n = 443) and infants (n = 747), to analyze CXCR3 expression levels in human placenta and levels of its ligands in umbilical cord blood, and to verify the influence of Cxcr3 on SPTB-associating cytokines in mice. We detected an association between an intronic CXCR3 polymorphism, rs2280964, and SPTB in infants from families with recurrent preterm births (p = 0.009 versus term controls, odds ratio 0.52, 95% confidence interval 0.32-0.86). The minor allele was protective and undertransmitted to SPTB infants (p = 0.007). In the placenta and fetal membranes, the rs2280964 major allele homozygotes had higher expression levels than minor allele homozygotes; decidual trophoblasts showed strong CXCR3 immunoreactivity. Expression was higher in SPTB placentas compared with those from elective deliveries. Concentration of a CXCR3 ligand, CXCL9, was increased in cord blood from SPTB, and the protective rs2280964 allele was associated with low CXCL9. In CXCR3-deficient mice (Mus musculus), SPTB-associating cytokines were not acutely increased in amniotic fluid after preterm birth-inducing dose of maternal LPS. Our results indicate that CXCR3 contributes to SPTB. Activation of CXCR3 signaling may disturb the maternal-fetal tolerance, and this may promote labor.

CXCR3 in carcinoma progression

CXCR3 is a G-protein coupled receptor which binds to ELR-negative CXC chemokines that have been found to impact immune responses, vascular develop, and wound repair. More recently, CXCR3 has been examined in the context of cancer and increased expression in many human tumors has been correlated with poor prognosis in breast, melanoma, colon and renal cancer patients. Three variants of CXCR3 are identified so far (CXCR3-A, CXCR3-B and CXCR3-alt) with the two primary ones, CXCR3-A and CXCR3-B, considered to induce opposite physiological functions. Generally, CXCR3-A, the predominant form in hematopoietic cells, appears to mediate tumor "go" signaling via promoting cell proliferation, survival, chemotaxis, invasion and metastasis; while CXCR3-B, the main form on formed elements including epithelial cells, appears to mediate tumor "stop" signaling via promoting growth suppression, apoptosis and vascular involution. Thus, aberrant expression of the isoforms CXCR3-A and CXCR3-B could affect tumor progression. In this review, we have discussed the profiles of CXCR3 variants and related signaling, as well as the role of CXCR3 variants in cancer.

Serum cytokine profile in patients with pancreatic cancer

OBJECTIVE

Pancreatic ductal adenocarcinoma is a deadly disease because of late diagnosis and chemoresistance. We aimed to find a panel of serum cytokines representing diagnostic and predictive biomarkers for pancreatic cancer.

METHODS

A cytokine antibody array was performed to simultaneously identify 507 cytokines in sera of patients with pancreatic cancer and healthy controls. The nonparametric Mann-Whitney U test was used to pairwise compare the controls, the pretreated patients, and the posttreated patients. Fold changes greater than or equal to 1.5 or less than or equal to 1/1.5 were considered significant. Receiver operating characteristic curves were used to assess the performance of the model. A leave-one-out cross-validation was used for estimating prediction error.

RESULTS

Comparing the sera of pretreated patients against the control samples, the cytokines fibroblast growth factor 10 (FGF-10/keratinocyte growth factor-2 (KGF-2), chemokine (C-X-C motif) ligand 11 interferon inducible T cell alpha chemokine (I-TAC)/chemokine [C-X-C motif] ligand 11 (CXCL11), oncostatin M (OSM), osteoactivin/glycoprotein nonmetastatic melanoma protein B, and stem cell factor (SCF) were found significantly overexpressed. Besides, the cytokines CD30 ligand/tumor necrosis factor superfamily, member 8 (TNFSF8), chordin-like 2, FGF-10/KGF-2, growth/differentiation factor 15, I-TAC/CXCL11, OSM, and SCF were differentially expressed in response to treatment.

CONCLUSIONS

We propose a role for FGF-10/KGF-2, I-TAC/CXCL11, OSM, osteoactivin/glycoprotein nonmetastatic melanoma protein B, and SCF as novel diagnostic biomarkers. CD30 ligand/TNFSF8, chordin-like 2, FGF-10/KGF-2, growth/differentiation factor 15, I-TAC/CXCL11, OSM, and SCF might represent as predictive biomarkers for gemcitabine and erlotinib response of patients with pancreatic cancer.

Cancer cell-derived lymphotoxin mediates reciprocal tumour-stromal interactions in human ovarian cancer by inducing CXCL11 in fibroblasts

We have investigated the role of cytokine lymphotoxin in tumour-stromal interactions in human ovarian cancer. We found that lymphotoxin overexpression is commonly shared by the cancer cells of various ovarian cancer subtypes, and lymphotoxin-beta receptor (LTBR) is expressed ubiquitously in both the cancer cells and cancer-associated fibroblasts (CAFs). In monoculture, we showed that ovarian cancer cells are not the major lymphotoxin-responsive cells. On the other hand, our co-culture studies demonstrated that the cancer cell-derived lymphotoxin induces chemokine expression in stromal fibroblasts through LTBR-NF-κB signalling. Amongst the chemokines being produced, we found that fibroblast-secreted CXCL11 promotes proliferation and migration of ovarian cancer cells via the chemokine receptor CXCR3. CXCL11 is highly expressed in CAFs in ovarian cancer biopsies, while CXCR3 is found in malignant cells in primary ovarian tumours. Additionally, the overexpression of CXCR3 is significantly associated with the tumour grade and lymph node metastasis of ovarian cancer, further supporting the role of CXCR3, which interacts with CXCL11, in promoting growth and metastasis of human ovarian cancer. Taken together, these results demonstrated that cancer-cell-derived lymphotoxin mediates reciprocal tumour-stromal interactions in human ovarian cancer by inducing CXCL11 in fibroblasts. Our findings suggest that lymphotoxin-LTBR and CXCL11-CXCR3 signalling represent therapeutic targets in ovarian cancer.

CXCR3, a double-edged sword in tumor progression and angiogenesis

CXC chemokines are involved in chemotaxis, regulation of cell growth, induction of apoptosis and modulation of angiostatic effects. CXCL9, CXCL10, CXCL11, CXCL4 and its variant CXCL4L1 are members of the CXC chemokine family, which bind to the CXCR3 receptor to exert their biological effects. These chemokines are associated with a variety of human diseases including chronic inflammation, immune dysfunction, cancer and metastasis. In this review, we focus on accumulating evidence demonstrating the pivotal role of CXCR3 in tumor progression. Its effects are mediated directly in tumor cells or indirectly through the regulation of angiogenesis and tumor immunity. Understanding the emerging role of CXCR3 and its signaling mechanisms further validates this receptor as a biomarker and therapeutic target for tumor progression and tumor angiogenesis.

Aberrant proliferation in CXCR7+ endothelial cells via degradation of the retinoblastoma protein

Angiogenesis is a critical factor in the growth and dissemination of solid tumors. Indeed, tumor vasculature is abnormal and contributes to the development and spread of malignancies by creating a hostile microenvironment. The alternative SDF-1/CXCL12 receptor, CXCR7, is frequently and specifically expressed in tumor-associated vessels. In this study, we examine the role of endothelium-expressed CXCR7 in tumor vascular dysfunction by specifically examining the contribution of CXCR7 to endothelial cell (EC) proliferation. We demonstrate that CXCR7 expression is sufficient to drive post-confluent growth in EC cultures. Further, we provide a novel mechanism for CXCR7-mediated proliferation via proteasomal degradation of the tumor suppressor protein Rb. These findings identify a heretofore unappreciated role for CXCR7 in vascular dysfunction and confirm this receptor as a plausible target for anti-tumor therapy.

Plasma endothelial protein C receptor influences innate immune response in ovarian cancer by decreasing the population of natural killer and TH17 helper cells

In spite of the growing importance of endothelial protein C receptor/active protein C (EPCR/aPC) in tumor biology, their impact on immunological homeostasis remains largely unexplored. The objective of this study was to assess whether soluble plasma endothelial protein C receptor (sEPCR), which is a regulator of circulating aPC, is involved in innate immune response in cancer patients. In the Ovcar-3 ovarian cancer line, the role of aPC in secretion of cytokines was analyzed. In parallel, in 33 patients, with a diagnosis of ovarian epithelial cancer, sEPCR was quantified, blood immune cell phenotypes were determined by flow cytometry and plasma cytokines were evaluated using a protein array. Spearman’s rank correlation coefficients (r) and coefficient significance was determined by a statistical hypothesis test (α=0.05). Our results show that i) aPC induced the secretion of several cytokines in Ovcar-3 cells; ii) 61% of patients exhibited a concentration of plasma sEPCR well above the baseline (normal plasma level, 100±28 ng/ml); iii) comparing immune cell phenotypes in patients having a normal level of sEPCR with those having a high level of sEPCR, it was found that sEPCR levels were correlated with high intensity of cells expressing CD45ra, CD3, CD8, CD25 and low intensity of cells expressing CD56 (NK cells), CD294 (TH2 cells), IL-2, IL-10, IL-17a (TH17 cells), IL-21 (TH21 cells) and CD29 markers (r ≥0.60); and iv) high levels of sEPCR correlate with high levels of plasma bioactive proteins such as insulin-like growth factor-2 (IGFII), IL-13rα, macrophage inflammatory protein (MIP1α) and matrix metalloproteinase-7 (MMP-7) that have already been proposed as biomarkers for ovarian cancer and particularly those with poor prognosis. In conclusion, sEPCR produced by ovarian cancer cells, by modulating circulating aPC, influences the secretory behavior of tumor cells (cytokines and interleukins). Consequently, sEPCR in turn acts on the innate immune response by decreasing effector cells such as natural killer and T helper cells (TH2, TH17 and TH21).

Molecular pathways: hepatitis C virus, CXCL10, and the inflammatory road to liver cancer

An estimated 170 million people worldwide are chronically infected with the hepatitis C virus (HCV), which is characterized histologically by a persistent immune and inflammatory response that fails to clear HCV from hepatocytes. This response is recruited to the liver, in part, by the chemokine CXCL10, the serum and intrahepatic levels of which have been inversely linked to the outcome of interferon-based therapies for hepatitis C. Bystander tissue damage from this ineffective response is thought to lead to increased hepatocyte turnover and the development of fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). However, CXCL10 is traditionally viewed as an orchestrator of the angiostatic and antitumor immune response. In this review, we will explore this duality and the pathways by which CXCL10 is produced by hepatocytes during HCV infection, its effects on resident and infiltrating immune cells, and how deregulation of these cell populations within the liver may lead to chronic liver inflammation. We will also discuss potential host-directed therapies to slow or reverse HCV-induced inflammation that leads to fibrosis, cirrhosis, and HCCs.

Chemokine receptor trio: CXCR3, CXCR4 and CXCR7 crosstalk via CXCL11 and CXCL12

Although chemokines are well established to function in immunity and endothelial cell activation and proliferation, a rapidly growing literature suggests that CXC Chemokine receptors CXCR3, CXCR4 and CXCR7 are critical in the development and progression of solid tumors. The effect of these chemokine receptors in tumorigenesis is mediated via interactions with shared ligands I-TAC (CXCL11) and SDF-1 (CXCL12). Over the last decade, CXCR4 has been extensively reported to be overexpressed in most human solid tumors and has earned considerable attention toward elucidating its role in cancer metastasis. To enrich the existing armamentarium of anti-cancerous agents, many inhibitors of CXCL12-CXCR4 axis have emerged as additional or alternative agents for neo-adjuvant treatments and even many of them are in preclinical and clinical stages of their development. However, the discovery of CXCR7 as another receptor for CXCL12 with rather high binding affinity and recent reports about its involvement in cancer progression, has questioned the potential of "selective blockade" of CXCR4 as cancer chemotherapeutics. Interestingly, CXCR7 can also bind another chemokine CXCL11, which is an established ligand for CXCR3. Recent reports have documented that CXCR3 and their ligands are overexpressed in different solid tumors and regulate tumor growth and metastasis. Therefore, it is important to consider the interactions and crosstalk between these three chemokine receptors and their ligand mediated signaling cascades for the development of effective anti-cancer therapies. Emerging evidence also indicates that these receptors are differentially expressed in tumor endothelial cells as well as in cancer stem cells, suggesting their direct role in regulating tumor angiogenesis and metastasis. In this review, we will focus on the signals mediated by this receptor trio via their shared ligands and their role in tumor growth and progression.

Ovarian cancer stroma: pathophysiology and the roles in cancer development

Ovarian cancer represents one of the cancers with the worst prognostic in adult women. More than half of the patients who present with clinical signs such as abdominal bloating and a feeling of fullness already show advanced stages. The majority of ovarian cancers grow as cystic masses, and cancer cells easily spread into the pelvic cavity once the cysts rupture or leak. When the ovarian cancer cells disseminate into the peritoneal cavity, metastatic nests may grow in the cul-de-sac, and in more advanced stages, the peritoneal surfaces of the upper abdomen become the next largest soil for cancer progression. Ascites is also produced frequently in ovarian cancers, which facilitates distant metastasis. Clinicopathologic, epidemiologic and molecular studies on ovarian cancers have improved our understanding and therapeutic approaches, but still further efforts are required to reduce the risks in the patients who are predisposed to this lethal disease and the mortality of the patients in advanced stages. Among various molecules involved in ovarian carcinogenesis, special genes such as TP53, BRCA1 and BRCA2 have been well investigated. These genes are widely accepted as the predisposing factors that trigger malignant transformation of the epithelial cells of the ovary. In addition, adnexal inflammatory conditions such as chronic salpingitis and ovarian endometriosis have been great research interests in the context of carcinogenic background of ovarian cancers. In this review, I discuss the roles of stromal cells and inflammatory factors in the carcinogenesis and progression of ovarian cancers.

The emerging role of CXC chemokines in epithelial ovarian cancer

In recent years, chemokines have generated intense investigations due to their involvement in both physiological and pathological processes of inflammation, particularly in ovarian biology. The physiological process of ovulation in the normal ovary involves various chemokines that mediate the healing of the ruptured endometrium. It is now being reported that many of these chemokines are also associated with the cancer of the ovary. Chronic inflammation underlies the progression of ovarian cancer; therefore, it raises the possibility that chemokines are involved in the inflammatory process and mediate immune responses that may favour or inhibit tumour progression. Ovarian cancer is a gynaecological cancer responsible for highest rate of mortality in women. Although there have been several investigations and advances in surgery and chemotherapy, the survival rate for this disease remains low. This is mainly because of a lack of specific symptoms and biomarkers for detection. In this review, we have discussed the emerging role of the CXC chemokines in epithelial ovarian cancer (EOC). The CXC group of chemokines is gaining importance in the field of ovarian cancer for being angiostatic and angiogenic in function. While there have been several studies on the angiogenesis function, emerging research shows that ELR(-) CXC chemokines, CXCL9 and CXCL10, are angiostatic. Importantly, the angiostatic chemokines can inhibit the progression of EOC. Given that there are currently no biomarkers or specific therapeutic targets for the disease, these chemokines are emerging as promising targets for therapy.

Impaired CXCL4 expression in tumor-associated macrophages (TAMs) of ovarian cancers arising in endometriosis

Inflammatory cells play important roles in progression of solid neoplasms including ovarian cancers. Tumor-associated macrophages (TAMs) contribute to angiogenesis and immune suppression by modulating microenvironment. Ovarian cancer develops occasionally on the bases of endometriosis, a chronic inflammatory disease. We have recently demonstrated differential expressions of CXCR3 variants in endometriosis and ovarian cancers. In this study, we showed impaired CXCL4 expression in TAMs of ovarian cancers arising in endometriosis. The expressions of CXCL4 and its variant CXCL4L1 were investigated among normal ovaries (n = 26), endometriosis (n = 18) and endometriosis-associated ovarian cancers (EAOCs) composed of clear cell (n = 13) and endometrioid (n = 11) types. In addition, four cases of EAOCs that contained both benign and cancer lesions contiguously in single cysts were investigated in the study. Western blot and quantitative RT-PCR analyses revealed significant downregulation of CXCL4 and CXCL4L1 in EAOCs compared with those in endometriosis. In all EAOCs coexisting with endometriosis in the single cyst, the expression levels of CXCL4 and CXCL4L1 were significantly lower in cancer lesions than in corresponding endometriosis. Histopathological study revealed that CXCL4 was strongly expressed in CD68⁺ infiltrating macrophages of endometriosis. In microscopically transitional zone between endometriosis and EAOC, CD68⁺ macrophages often demonstrated CXCL4⁻ pattern. The majority of CD68⁺ TAMs in overt cancer lesions were negative for CXCL4. Collective data indicate that that CXCL4 insufficiency may be involved in specific inflammatory microenvironment of ovarian cancers arising in endometriosis. Suppression of CXCL4 in cancer lesions is likely to be attributable to TAMs in part.

Activated expression of the chemokine Mig after chemotherapy contributes to chemotherapy-induced bone marrow suppression and lethal toxicity

Alterations in gene expression after chemotherapy may potentially help to identify mediators that induce suppression or regeneration in bone marrow. This paper reports our observation that the expression of the chemokine monokine induced by IFN-γ (Mig) and its receptor CXCR3 was significantly activated in mice after treatment with the chemotherapeutic agent 5-fluorouracil (5-FU). The neutralization of antibodies against the activated Mig increased the survival rate and accelerated BM recovery after chemotherapy. In addition, elevation of Mig plasma levels after 5-FU treatment corresponded with increased mortality. The cell cycle-inhibiting effect of the prophylactic administration of Mig protected hematopoietic progenitor cells (HPCs) from 1-β-d-arabinofuranosylcytosine in spleen colony assays and enhanced the irradiated recipients' survival. In CXCR3(-/-) mice, Mig did not propagate BM suppression, indicating that the suppressive effect of Mig is dependent on CXCR3. On the one hand, Mig stimulated p70 S6K and Erk1/2 pathways in mesenchymal stroma cells, inhibiting mesenchymal stroma cell-dependent HPC expansion. Moreover, Mig suppressed the STAT5 pathway in HPCs, inhibiting leukocyte differentiation. Our results strongly suggest that Mig contributes to the acute lethal toxicity arising from 5-FU administration. Neutralization of Mig may offer new strategies to alleviate BM toxicity with potentially dramatic implications for chemotherapy.