CXC-chemokines stimulate invasion and chemotaxis in prostate carcinoma cells through the CXCR2 receptor

Involvement in Tumorigenesis and Clinical Significance of CXCL1 in Reproductive Cancers: Breast Cancer, Cervical Cancer, Endometrial Cancer, Ovarian Cancer and Prostate Cancer

C-X-C motif chemokine ligand 1 (CXCL1) is a member of the CXC chemokine subfamily and a ligand for CXCR2. Its main function in the immune system is the chemoattraction of neutrophils. However, there is a lack of comprehensive reviews summarizing the significance of CXCL1 in cancer processes. To fill this gap, this work describes the clinical significance and participation of CXCL1 in cancer processes in the most important reproductive cancers: breast cancer, cervical cancer, endometrial cancer, ovarian cancer, and prostate cancer. The focus is on both clinical aspects and the significance of CXCL1 in molecular cancer processes. We describe the association of CXCL1 with clinical features of tumors, including prognosis, ER, PR and HER2 status, and TNM stage. We present the molecular contribution of CXCL1 to chemoresistance and radioresistance in selected tumors and its influence on the proliferation, migration, and invasion of tumor cells. Additionally, we present the impact of CXCL1 on the microenvironment of reproductive cancers, including its effect on angiogenesis, recruitment, and function of cancer-associated cells (macrophages, neutrophils, MDSC, and T_reg). The article concludes by summarizing the significance of introducing drugs targeting CXCL1. This paper also discusses the significance of ACKR1/DARC in reproductive cancers.

Targeting of the ELR+CXCL/CXCR1/2 Pathway Is a Relevant Strategy for the Treatment of Paediatric Medulloblastomas

Medulloblastoma (MB) is the most common and aggressive paediatric brain tumour. Although the cure rate can be as high as 70%, current treatments (surgery, radio- and chemotherapy) excessively affect the patients' quality of life. Relapses cannot be controlled by conventional or targeted treatments and are usually fatal. The strong heterogeneity of the disease (four subgroups and several subtypes) is related to innate or acquired resistance to reference treatments. Therefore, more efficient and less-toxic therapies are needed. Here, we demonstrated the efficacy of a novel inhibitor (C29) of CXCR1/2 receptors for ELR+CXCL cytokines for the treatment of childhood MB. The correlation between ELR+CXCL/CXCR1/2 expression and patient survival was determined using the R2: Genomics Analysis and Visualization platform. In vitro efficacy of C29 was evaluated by its ability to inhibit proliferation, migration, invasion, and pseudo-vessel formation of MB cell lines sensitive or resistant to radiotherapy. The growth of experimental MB obtained by MB spheroids on organotypic mouse cerebellar slices was also assayed. ELR+CXCL/CXCR1/2 levels correlated with shorter survival. C29 inhibited proliferation, clone formation, CXCL8/CXCR1/2-dependent migration, invasion, and pseudo-vessel formation by sensitive and radioresistant MB cells. C29 reduced experimental growth of MB in the ex vivo organotypic mouse model and crossed the blood-brain barrier. Targeting CXCR1/2 represents a promising therapeutic strategy for the treatment of paediatric MB in first-line treatment or after relapse following conventional therapy.

CLDN6 inhibits breast cancer cell malignant behavior by suppressing ERK signaling

Claudin 6 (CLDN6) is an important component of tight junctions. Through the PDZ binding motif, CLDN6 binds to a variety of signaling proteins that contain the PDZ domain to regulate different signaling pathways, and plays an important role in the occurrence and development of tumors. Our previous work showed that CLDN6 was expressed at low levels in breast cancer cells, and overexpression of CLDN6 inhibited breast cancer cell proliferation, migration and invasion. However, the mechanism of how CLDN6 works remains unclear. In this study, we aimed to explore the mechanism by which CLDN6 inhibits breast cancer cell malignant behavior. As a result, overexpression of CLDN6 inhibited the proliferation of breast cancer cells along with the downregulation of cyclin D1, which plays an important role in regulating cell proliferation. After overexpression of Sp1 in CLDN6-overexpressing cells, the expression of cyclin D1 was upregulated. On the other hand, CLDN6 inhibited breast cancer cell migration and invasion along with the downregulation of IL-8, CXCR2 and FAK. When treated with IL-8, the migration and invasion ability were promoted along with the upregulation of CXCR2 and p-FAK, and the cytoskeleton was rearranged in CLDN6-overexpressing cells. Furthermore, when treated with the ERK signaling activator PMA, the proliferation, migration and invasion abilities were promoted along with the upregulation of Sp1, cyclin D1 and IL-8 in CLDN6-overexpressin cells. In conclusion, CLDN6 suppressed ERK/Sp1/cyclin D1 and ERK/IL-8 signaling to inhibit proliferation, migration and invasion in breast cancer cells. The mechanism may provide experimental evidence for the treatment of breast cancer targeting CLDN6.

Dura promotes metastatic potential in prostate cancer through the CXCR2 pathway

PURPOSE

Spinal metastases are common in cancer. This preferential migration/growth in the spine is not fully understood. Dura has been shown to affect the surrounding microenvironment and promote cancer growth. Here, we investigate the role of dural cytokines in promoting the metastatic potential of prostate cancer (PCa) and the involvement of the CXCR2 signaling pathway.

METHODS

The role of dural conditioned media (DCM) in proliferation, migration and invasion of five PCa cell lines with various hormone sensitivities was assessed in the presence or absence of the CXCR2 inhibitor, SB225002. CXCR2 surface protein was examined by FACS. Cytokine levels were measured using a mouse cytokine array.

RESULTS

We observed high levels of cytokines produced by dura and within the vertebral body bone marrow, namely CXCL1 and CXCL2, that act on the CXCR2 receptor. All prostate cell lines treated with DCM demonstrated significant increase in growth, migration and invasion regardless of androgen sensitivity, except PC3, which did not significantly increase in invasiveness. When treated with SB225002, the growth response to DCM by cells expressing the highest levels of CXCR2 as measured by FACS (LNCaP and 22Rv1) was blunted. The increase in migration was significantly decreased in all lines in the presence of SB225002. Interestingly, the invasion increase seen with DCM was unchanged when these cells were treated with the CXCR2 inhibitor, except PC3 did demonstrate a significant decrease in invasion.

CONCLUSION

DCM enhances the metastatic potential of PCa with increased proliferation, migration and invasion. This phenomenon is partly mediated through the CXCR2 pathway.

An overview of the role of interleukin-8 in colorectal cancer

Colorectal Cancer (CRC), a common malignancy, is developing globally among people. Mutagenic insults activate peripheral nucleated cells to secrete chemokines in order to cause an inflammatory state. Despite the presence of multi-retrieving factors, elevated production of minor cytokines may speed-up the sever stages of the baseline inflammation targeting normal compensatory mechanism. IL-8 is a pro-inflammatory cytokine that is believed to be up-regulated in CRC to proceed primary condition into tumor behavior via induction of proliferation, angiogenesis and metastasis. Here, we assess the role of IL-8 in every step of CRC from signaling pathway and formation to invasion and discuss around new perspective therapy that targets IL-8 to manage CRC worldwide incidence and survival rate, more precisely.

UV Light-inactivated HSV-1 Stimulates Natural Killer Cell-induced Killing of Prostate Cancer Cells

Herein we demonstrate that ultraviolet light-inactivated Herpes Simplex Virus-1 (UV-HSV-1) stimulates peripheral blood mononuclear cells (PBMCs) to lyse both androgen-sensitive and androgen-independent prostate cancer (PrCA) cell lines, but not the benign prostatic hyperplastic epithelial cell line, BPH-1, and is 1000-10,000-fold more potent at stimulating this killing than ultraviolet light-inactivated Vesicular Stomatitis Virus, adenovirus, reovirus or cytomegalovirus. Among PBMCs, natural killer (NK) cells appear to be a major cell type involved in this killing and UV-HSV-1 appears to directly and potently stimulate NK cell expression of CD69, degranulation, cytokine production, and migration to IL-8 in PC3 conditioned medium. We also found that UV-HSV-1 stimulates glycolysis in PBMCs and NK cells, and that 2-deoxyglucose and the protein kinase C inhibitor, Go6976, and the NFκB inhibitor, Bay 11-7082, all abrogate UV-HSV-1 activated killing of PC3 cells by PBMCs and NK cells. Using neutralizing anti-Toll-like receptor 2 (TLR2) we found that UV-HSV-1, like HSV-1, activates NK cells via TLR2. Taken together, these results are consistent with Toll-like receptor 2 ligands on UV-HSV-1 stimulating TLR2 on NK cells to activate protein kinase C, leading to enhanced glycolysis and NFκB activation, both of which play a critical role in this anti-PrCA innate immune response. Importantly, UV-HSV-1 synergizes with IL-15 to increase the cytolytic activity of PBMCs against PC3 cells and there was considerable donor-to-donor variation in killing ability. These results support the preclinical development of UV-HSV-1 as an adjuvant, in combination with IL-15, for cell infusions of healthy, preselected NK cells to treat PrCA.

Use of STAT6 Phosphorylation Inhibitor and Trimethylglycine as New Adjuvant Therapies for 5-Fluorouracil in Colitis-Associated Tumorigenesis

Colorectal cancer (CRC) is one of the most widespread and deadly types of neoplasia around the world, where the inflammatory microenvironment has critical importance in the process of tumor growth, metastasis, and drug resistance. Despite its limited effectiveness, 5-fluorouracil (5-FU) is the main drug utilized for CRC treatment. The combination of 5-FU with other agents modestly increases its effectiveness in patients. Here, we evaluated the anti-inflammatory Trimethylglycine and the Signal transducer and activator of transcription (STAT6) inhibitor AS1517499, as possible adjuvants to 5-FU in already established cancers, using a model of colitis-associated colon cancer (CAC). We found that these adjuvant therapies induced a remarkable reduction of tumor growth when administrated together with 5-FU, correlating with a reduction in STAT6-phosphorylation. This reduction upgraded the effect of 5-FU by increasing both levels of apoptosis and markers of cell adhesion such as E-cadherin, whereas decreased epithelial-mesenchymal transition markers were associated with aggressive phenotypes and drug resistance, such as β-catenin nuclear translocation and Zinc finger protein SNAI1 (SNAI1). Additionally, Il-10, Tgf-β, and Il-17a, critical pro-tumorigenic cytokines, were downmodulated in the colon by these adjuvant therapies. In vitro assays on human colon cancer cells showed that Trimethylglycine also reduced STAT6-phosphorylation. Our study is relatively unique in focusing on the effects of the combined administration of AS1517499 and Trimethylglycine together with 5-FU on already established CAC which synergizes to markedly reduce the colon tumor load. Together, these data point to STAT6 as a valuable target for adjuvant therapy in colon cancer.

The significance of chemokine CXCL-8 in esophageal carcinoma

Chemokines are a group of small molecular weight proteins that are structurally related. These molecules play an important role in the growth, differentiation and activation of many types of cells [1, 2]. Chemokines are synthesized mostly by leukocytes and act through their cognate G-protein coupled receptors to cause a cellular response, such as migration, adhesion or chemotaxis [1, 3]. The chemokine family has been classified into four classes: CC, CXC, CX3C, and (X), based on the arrangement of N-terminal cysteine residues [4]. These small peptides may also be grouped into inflammatory, homeostatic or dual function chemokines. Inflammatory chemokines can be induced during an immune response, whereas homeostatic chemokines are involved in control of cell migration [5]. The chemokine receptors are seven-transmembrane receptors coupled to G-proteins, that consist of an N-terminus outside the cell surface, three extracellular and three intracellular loops as well as a C-terminus in the cytoplasm [6, 7].

IL-8 promotes cell migration through regulating EMT by activating the Wnt/β-catenin pathway in ovarian cancer

Interleukin‐8 (IL‐8), as an inflammatory chemokine, has been previously shown to contribute to tumorigenesis in several malignancies including the ovarian cancer. However, little is known about how IL‐8 promotes the metastasis and invasion of ovarian cancers cells. In this study, we found that IL‐8 and its receptors CXCR1 and CXCR2 were up‐regulated in advanced ovarian serous cancer tissues. Furthermore, the level of IL‐8 and its receptors CXCR1 and CXCR2 expression were associated with ovarian cancer stage, grade and lymph node metastasis. In vitro, IL‐8 promoted ovarian cancer cell migration, initiated the epithelial‐mesenchymal transition (EMT) program and activated Wnt/β‐catenin signalling. However, when treated with Reparixin (inhibitor of both IL‐8 receptors CXCR1 and CXCR2), effect of both endogenous and exogenous IL‐8 was reversed. Together, our results indicated that IL‐8 triggered ovarian cancer cells migration partly through Wnt/β‐catenin pathway mediated EMT, and IL‐8 may be an important molecule in the invasion and metastasis of ovarian cancer.

Fluid shear stress-induced IL-8/CXCR signaling in human ovarian cancer cells

Background

Interleukin-8 (IL-8) released from mechanosensitive cancer cells plays a key role in the inflammation and metastasis of solid carcinomas. In this study, we have explored IL-8 and its receptors signal transduction process of human ovarian cancer cells under conditions of FSS.

Methods

After the fluid shear stress was loaded, LightCycler™ system and quantitative sandwich ELISA were employed to assay the IL-8 mRNA expression and protein production, respectively. IL-8 reporter gene pEGFP1-IL8USCS was constructed for determining IL-8 gene transcriptional activation through gene transfer and flow cytometric analysis. NF-κB nuclear translocation was observed by immunocytofluorescent staining. Western blot was used to examine IκB phosphorylation and degradation. RT-PCR, Northern blot and immunofluorescence were used to determine the expression of a cell-surface chemokine receptor CXCR2 at mRNA and protein levels.

Results

IL-8 mRNA expression and protein production had biphasic responses to low shear stress (1.5 dyne/cm²), with the peaks at 1 and 2 h respectively. There was an increase in enhanced green fluorescent protein expression in pEGFP1-IL8USCS-transfected SKOV3 cells subjected to a fluid shear stress of 1.5 dyne/cm² for 2 h. Following the application of shear stress of 1.5 dyne/cm², NF-κB p65 became detectable in the cell nuclei, and Phosphorylated IκB in cell lysates increased significantly. CXCR2, which was constitutively present on the surface of SKOV3 cells, increased following exposure to fluid shear stress for 60 min.

Conclusions

Fluid shear stress triggered IL-8/CXCR2 signaling of SKOV3 cells is an early gene activation, and the activation can be mediated through NF-κB. This observation suggested that fluid shear stress-induced IL-8 activation and the downstream signal pathways may have an important contribution to the pathogenesis and development of both inflammation and metastasis of ovarian carcinomas.

Chemokine Receptors and Exercise to Tackle the Inadequacy of T Cell Homing to the Tumor Site

While cancer immune therapy has revolutionized the treatment of metastatic disease across a wide range of cancer diagnoses, a major limiting factor remains with regard to relying on adequate homing of anti-tumor effector cells to the tumor site both prior to and after therapy. Adoptive cell transfer (ACT) of autologous T cells have improved the outlook of patients with metastatic melanoma. Prior to the approval of checkpoint inhibitors, this strategy was the most promising. However, while response rates of up to 50% have been reported, this strategy is still rather crude. Thus, improvements are needed and within reach. A hallmark of the developing tumor is the evasion of immune destruction. Achieved through the recruitment of immune suppressive cell subsets, upregulation of inhibitory receptors and the development of physical and chemical barriers (such as poor vascularization and hypoxia) leaves the microenvironment a hostile destination for anti-tumor T cells. In this paper, we review the emerging strategies of improving the homing of effector T cells (TILs, CARs, TCR engineered T cells, etc.) through genetic engineering with chemokine receptors matching the chemokines of the tumor microenvironment. While this strategy has proven successful in several preclinical models of cancer and the strategy has moved into the first phase I/II clinical trial in humans, most of these studies show a modest (doubling) increase in tumor infiltration of effector cells, which raises the question of whether road blocks must be tackled for efficient homing. We propose a role for physical exercise in modulating the tumor microenvironment and preparing the platform for infiltration of anti-tumor immune cells. In a time of personalized medicine and genetic engineering, this "old tool" may be a way to augment efficacy and the depth of response to immune therapy.

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

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

CXCL8 derived from tumor-associated macrophages and esophageal squamous cell carcinomas contributes to tumor progression by promoting migration and invasion of cancer cells

Tumor-associated macrophages (TAMs) are involved in tumor progression and poor prognosis in several malignancies. We previously demonstrated the interaction between high numbers of infiltrating TAMs and poor prognosis in esophageal squamous cell carcinomas (ESCCs). To investigate the significance of TAMs in ESCC, we conducted a cDNA microarray analysis of peripheral blood monocytes (PBMo)-derived macrophages and PBMo-derived macrophages stimulated with conditioned media of TE-series ESCC cell lines (TAM-like PBMo-derived macrophages). C-X-C motif chemokine ligand 8 (CXCL8) was up-regulated in the TAM-like PBMo-derived macrophages. Here we confirmed a high expression level of CXCL8 in TAM-like PBMo-derived macrophages and the expression of CXCR1/2, known as CXCL8 receptors, in TE-series ESCC cell lines. Recombinant human CXCL8 induced the ESCC cell lines’ migration and invasion by the phosphorylation of Akt and Erk1/2. In indirect co-cultures, not only signal pathway inhibitors but also neutralizing antibodies against CXCL8, CXCR1 and CXCR2 suppressed these phenotypes induced by TAM-like PBMo-derived macrophages. Immunohistochemical analysis of 70 resected ESCC samples showed that high expression levels of CXCL8 in ESCC tissues were significantly associated with lymph node metastasis and poor prognosis. These results suggest that CXCL8 up-regulated in the microenvironment may contribute to ESCC progression by promoting cancer cells’ migration and invasion.

UNBS5162 inhibits proliferation of human retinoblastoma cells by promoting cell apoptosis

Human retinoblastomas are malignant intraocular tumors and have a high incidence in children. Chemotherapy combined with local therapy is the principal means of retinoblastoma treatment, the application of which has saved the eye of many children and avoided external irradiation. UNBS5162, a naphthalimide, has broad prospects as a tumor treatment, with fewer toxic side effects and higher cancer-suppression efficiency. However, the efficacy of UNBS5162 in human retinoblastomas is still not clear. In the present study, we investigated the specific mechanism of UNBS5162 in the human retinoblastoma cell lines WERIRb1 and Y79. Compared with a negative-control (NC) group, UNBS5162 treatment for 72 hours significantly decreased cell proliferation; meanwhile, more apoptotic cells were observed in the UNBS5162-treated group (27.1% in WERIRb1, 20.83% in Y79) than in the NC group (11.59% in WERIRb1, 12.89% in Y79). We also found caspase 3 p17 and Bax expression to be upregulated and Bcl2 downregulated significantly in UNBS5162-treated WERIRb1 and Y79 cells. The effects of UNBS5162 on human retinoblastoma cells may be regulated by the Akt–mTOR pathway. We found expression of the Akt pathway and key proliferation-related genes – those for p-Akt, p-mTOR, p70, and cyclin D₁ – were downregulated significantly in the UNBS5162-treated group compared with the NC group in WERIRb1 and Y79. Therefore, for the first time, we demonstrated that UNBS5162 can inhibit proliferation and promote apoptosis of human retinoblastoma cells by regulating activity of the Akt–mTOR pathway in vitro, suggesting the potential value of UNBS5162 in treatment for human retinoblastoma.

CXCR2-CXCL1 axis is correlated with neutrophil infiltration and predicts a poor prognosis in hepatocellular carcinoma

Background & aims

Inflammation is a hallmark of cancer, yet the mechanisms that regulate immune cell infiltration into tumors remain poorly characterized. This study attempted to characterize the composition, distribution, and prognostic value of CXCR2⁺ cells in hepatocellular carcinoma (HCC) and to examine the CXCR2 ligands that are responsible for local immune infiltration in different areas of HCC tumors.

Methods

Immunohistochemistry and immunofluorescene were used to identify CXCR2⁺ cells in HCC tissues. Kaplan–Meier analysis and Cox regression models were applied to estimate recurrence-free survival (RFS) and overall survival (OS) for 259 HCC patients. The expression levels of CXCR2 ligands (CXCL-1, −2, −5, and −8) were measured by real-time PCR and compared with local immune cell density. The combined prognostic value of the CXCR2–CXCL1 axis was further evaluated.

Results

In HCC tissues, CXCR2⁺ cells were mainly neutrophils that were enriched in the peri-tumoral stroma (PS) region. Kaplan–Meier survival analysis showed that increased CXCR2⁺_PS cells were associated with reduced RFS and OS (P = 0.015 for RFS; P = 0.002 for OS). Multivariate Cox proportional hazards analysis identified CXCR2⁺_PS cell density as an independent prognostic factor for OS (hazard ratio [HR] = 1.737, 95 % confidence interval [CI] = 1.167–2.585, P = 0.006). Furthermore, we detected a positive correlation between the density of CD15⁺ neutrophils and CXCL1 levels in both the peri-tumoral stroma and intra-tumoral regions. The combination of CXCR2 and CXCL1 expression levels represented a powerful predictor of a poor prognosis for patients with HCC.

Conclusions

Our data showed that the CXCR2⁺ cell density was an independent prognostic factor for predicting OS for HCC patients. The CXCR2–CXCL1 axis can regulate neutrophil infiltration into HCC tumor tissues and might represent a useful target for anti-HCC therapies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0247-1) contains supplementary material, which is available to authorized users.

Role of CXCL12 and CXCR4 in normal cerebellar development and medulloblastoma

Chemokines and its receptors have significant impact on physiological and pathological processes and studies concerning their association with tumor biology are subject of great interest in scientific community. CXCL12/CXCR4 axis has been widely studied due to its significant role in tumor microenvironment, but it is also important to development and maintenance of tissues and organs, for example, in the brain and cerebellum. Studies have demonstrated that CXCL12 and CXCR4 are required for normal cerebellar development and that dysfunction in this pathway may be involved with medulloblastoma pathogenesis. In this context, a new molecular subgroup has been suggested based on the importance of the association between CXCR4 overexpression and sonic hedgehog subgroup. Treatment using CXCR4 antagonists showed significant results, evidencing the important role and possible therapeutic capacity of CXCR4 in MB. This review summarizes studies on MB cell biology, focusing on a chemokine-receptor axis, CXCL12/CXCR4, that may have implications for treatment strategies once it can improve life expectancy and reduce neurocognitive sequelae of patients with this neoplasia.

CXCR2/CXCL5 axis contributes to epithelial-mesenchymal transition of HCC cells through activating PI3K/Akt/GSK-3β/Snail signaling

Upregulation of CXCR2 in tumor cells has been documented in several types of cancer. As one of its ligands, CXCL5 is associated with neutrophil infiltration and poor prognosis in hepatocellular carcinoma (HCC). However, little is known about the role of the CXCR2/CXCL5 axis in the invasion and metastasis of HCC cells. In this study, we examined CXCR2 expression in human HCC cell lines and in three independent cohorts of HCC patients. The molecular effects of high expression levels of CXCR2 and CXCL5 in HCC cells were determined using qRT-PCR, western blot analysis, immunofluorescence, matrigel invasion assay, and xenograft mouse models. We found that high levels of CXCR2 correlated with progression and poor prognosis in human HCC. CXCR2/CXCL5 together promoted cell spreading by inducing the epithelial-mesenchymal transition (EMT) through activation of the PI3K/Akt/GSK-3β/Snail signaling pathway. In clinical HCC samples, high expression of both CXCR2 and CXCL5 showed a significant correlation with the activation of PI3K/Akt/GSK-3β/Snail signaling and EMT phenotype. In conclusion, our data showed that the CXCR2/CXCL5 axis contributes to EMT of HCC cells through activating PI3K/Akt/GSK-3β/Snail signaling, and it may serve as a potential therapeutic target.

Interleukin-8 induces DNA synthesis, migration and down-regulation of cleaved caspase-3 in cultured human gingival epithelial cells

BACKGROUND AND OBJECTIVE

Migration of the junctional epithelium occurs in association with the formation of a periodontal pocket. Although the migration of junctional epithelium is known to be related to the proliferation and migration of gingival junctional epithelial cells, the mechanism has not been clarified. In patients with periodontitis, the levels of interleukin-8 (IL-8) in both gingival tissue and gingival crevicular fluid are dramatically increased. IL-8 has broad bioactive functions. In this study, we examined the role of IL-8 in DNA synthesis, migration and protection against apoptosis in cultured human gingival epithelial cells (HGEC).

MATERIAL AND METHODS

DNA synthesis was estimated by measuring the incorporation of bromodeoxyuridine. The migration of gingival epithelial cells was assessed in a wound-healing assay. The expression of integrin beta-1 was analyzed using immunofluorescence confocal microscopy and western blotting. Cleaved caspase-3 was detected using western blotting and a Caspase-Glo assay kit.

RESULTS

IL-8 increased the synthesis of DNA in HGEC, and the maximal effect was seen at 25 or 50 ng/mL of IL-8. In addition, 50 ng/mL of IL-8 induced cell migration, and a neutralizing antibody of integrin beta-1 inhibited the migration. IL-8 also activated expression of integrin beta-1. Furthermore, IL-8 reduced the Aggregatibacter actinomycetemcomitans-induced increase in caspase-3 expression in HGEC.

CONCLUSION

IL-8 may facilitate the migration of gingival junctional epithelium by enhancing DNA synthesis, migration and preventing apoptosis of gingival epithelial cells.

Interleukin-8 promotes cell migration through integrin αvβ6 upregulation in colorectal cancer

Colorectal cancer (CRC), which is notorious for high morbidity and mortality around the world, shows a predilection for metastasis to liver. Interleukin-8 (IL-8), a chemokine with a defining CXC amino acid motif, has been reported to promote CRC cell migration and is associated with poor prognosis of CRC. However, the underlying molecular mechanism of IL-8-mediated migration remains obscure. In this study, we first demonstrated the cross talk between IL-8 and integrin αvβ6. We analyzed 139 human CRC samples, and found that the immunohistochemical expression of αvβ6 was significantly correlated with expression of IL-8. Furthermore, IL-8 increased the migration through integrin αvβ6 in human CRC cells, and both CXCR1 and CXCR2 were primarily involved during the process. IL-8 upregulated αvβ6 expression in a dose-dependent manner through activation of ERK and Ets-1 signaling pathway. Taken together, our results indicated that IL-8 enhances the migration of CRC cells by increasing αvβ6 integrin expression through the ERK/Ets-1 pathway. Targeting integrin αvβ6 in IL-8 expressing tumors might be a potential therapeutic strategy for CRC patients.

Reflux composition influences the level of NF-κB activation and upstream kinase preference in oesophageal adenocarcinoma cells

Oesophageal adenocarcinoma (OA) incidence is rising and prognosis is poor. Understanding the molecular basis of this malignancy is key to finding new prevention and treatment strategies. Gastroesophageal reflux disease is the primary cause of OA, usually managed with acid suppression therapy. However, this often does little to control carcinogenic bile acid reflux. The transcription factor nuclear factor kappa B (NF-κB) plays a key role in the pathogenesis of OA and its activity is associated with a poor response to chemotherapy, making it an attractive therapeutic target. We sought to decipher the role of different bile acids in NF-κB activation in oesophageal cell lines using short, physiologically relevant exposure times. The effect of an acidic or neutral extracellular pH was investigated concurrently, to mimic in vivo conditions associated with or without acid suppression. We found that some bile acids activated NF-κB to a greater extent when combined with acid, whereas others did so in its absence, at neutral pH. The precise composition of an individual's reflux, coupled with whether they are taking acid suppressants may therefore dictate the extent of NF-κB activation in the oesophagus, and hence the likelihood of histological progression and chemotherapy success. Regardless of pH, the kinase inhibitor of κB kinase was pivotal in mediating reflux induced NF-κB activation. Its importance was confirmed further as its increased activation was associated with histological progression in patient samples. We identified further kinases important in acid or bile induced NF-κB signalling in oesophageal cells, which may provide suitable targets for therapeutic intervention.

Dynamic interplay between breast cancer cells and normal endothelium mediates the expression of matrix macromolecules, proteasome activity and functional properties of endothelial cells

BACKGROUND

Breast cancer-endothelium interactions provide regulatory signals facilitating tumor progression. The endothelial cells have so far been mainly viewed in the context of tumor perfusion and relatively little is known regarding the effects of such paracrine interactions on the expression of extracellular matrix (ECM), proteasome activity and properties of endothelial cells.

METHODS

To address the effects of breast cancer cell (BCC) lines MDA-MB-231 and MCF-7 on the endothelial cells, two cell culture models were utilized; one involves endothelial cell culture in the presence of BCCs-derived conditioned media (CM) and the other co-culture of both cell populations in a Transwell system. Real-time PCR was utilized to evaluate gene expression, an immunofluorescence assay for proteasome activity, and functional assays (migration, adhesion and invasion) and immunofluorescence microscopy for cell integrity and properties.

RESULTS

BCC-CM decreases the cell migration of HUVEC. Adhesion and invasion of BCCs are favored by HUVEC and HUVEC-CM. HA levels and the expression of CD44 and HA synthase-2 by HUVEC are substantially upregulated in both cell culture approaches. Adhesion molecules, ICAM-1 and VCAM-1, are also highly upregulated, whereas MT1-MMP and MMP-2 expressions are significantly downregulated in both culture systems. Notably, the expression and activity of the proteasome β5 subunit are increased, especially by the action of MDA-MB-231-CM on HUVEC.

CONCLUSIONS AND GENERAL SIGNIFICANCE

BCCs significantly alter the expression of matrix macromolecules, proteasome activity and functional properties of endothelial cells. Deep understanding of such paracrine interactions will help to design novel drugs targeting breast cancer at the ECM level. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Role of CXCR2 and TRPV1 in functional, inflammatory and behavioural changes in the rat model of cyclophosphamide-induced haemorrhagic cystitis

BACKGROUND AND PURPOSE

Cyclophosphamide induces urotoxicity characterized by the development of cystitis, which involves bladder overactivity and inflammation. Here, we investigated the roles of chemokine receptor 2 (CXCR2) and transient receptor potential vanilloid 1 (TRPV1) channels in a rat model of cyclophosphamide-induced cystitis.

EXPERIMENTAL APPROACH

Cystitis induced by cyclophosphamide in rats was assessed by gross morphology, histology and immunohistochemistry of bladder tissue. mRNA for CXCR2 and TRPV1 channels were measured by RT-PCR. Nociceptive responses in paw and abdomen, along with cystometric measures were recorded.

KEY RESULTS

Cyclophosphamide, i.p., induced pain behaviour, bladder inflammation and voiding dysfunction. The CXCR2 antagonist, SB225002, the TRPV1 channel antagonist, SB366791 or their combination reduced the mechanical hypersensitivity of paw and abdominal area and nociceptive behaviour after cyclophosphamide. Cyclophosphamide-induced cystitis was characterized by haemorrhage, oedema, neutrophil infiltration and other inflammatory changes, which were markedly decreased by the antagonists. Up-regulation of CXCR2 and TRPV1 mRNA in the bladder after cyclophosphamide was inhibited by SB225002, SB366791 or their combination. Expression of CXCR2 and TRPV1 channels was increased in the urothelium after cyclophosphamide. Bladder dysfunction was shown by increased number of non-voiding contractions (NVCs) and bladder pressures and a reduction in bladder capacity (BC), voided volume (VV) and voiding efficiency (VE). SB225002 or its combination with SB366791 reduced bladder pressures, whereas SB225002, SB366791 or their combination increased BC, VV and VE, and also reduced the number of NVCs.

CONCLUSIONS AND IMPLICATIONS

CXCR2 and TRPV1 channels play important roles in cyclophosphamide-induced cystitis in rats and could provide potential therapeutic targets for cystitis.

Rationale and Means to Target Pro-Inflammatory Interleukin-8 (CXCL8) Signaling in Cancer

It is well established that chronic inflammation underpins the development of a number of human cancers, with pro-inflammatory signaling within the tumor microenvironment contributing to tumor progression and metastasis. CXCL8 is an ELR⁺ pro-inflammatory CXC-chemokine which mediates its effects via signaling through two G protein-coupled receptors, CXCR1 and CXCR2. Elevated CXCL8-CXCR1/2 signaling within the tumor microenvironment of numerous cancers is known to enhance tumor progression via activation of signaling pathways promoting proliferation, angiogenesis, migration, invasion and cell survival. This review provides an overview of established roles of CXCL8-CXCR1/2 signaling in cancer and subsequently, discusses the possible strategies of targeting CXCL8-CXCR1/2 signaling in cancer, covering indirect strategies (e.g., anti-inflammatories, NFκB inhibitors) and direct CXCL8 or CXCR1/2 inhibition (e.g., neutralizing antibodies, small molecule receptor antagonists, pepducin inhibitors and siRNA strategies). Reports of pre-clinical cancer studies and clinical trials using CXCL8-CXCR1/2-targeting strategies for the treatment of inflammatory diseases will be discussed. The future translational opportunities for use of such agents in oncology will be discussed, with emphasis on exploitation in stratified populations.

Impact of CXCL1 overexpression on growth and invasion of prostate cancer cell

BACKGROUND

The role of CXCL1 in prostate cancer (PCa) progression has been poorly investigated. A limitation of previous studies is linked to the use of human PCa cell lines PC3 and DU145, producing CXCL8 at levels strongly exceeding CXCL1 levels. Moreover, in mouse models the sharing of CXCR2 receptor by both ligands makes the phenotype induced by CXCL8 and CXCL1 almost indistinguishable. To overcome this problem we used the murine TRAMP-C2 cell line, not expressing CXCL8 and expressing CXCL1 at low levels.

METHODS

The effect of CXCL1 overexpression was examined by in vivo subcutaneous tumor studies and in vitro functional assays of invasion and adhesion. Biochemical modifications were evaluated by Western blotting and antibody arrays.

RESULTS

Our data show that the overexpression of CXCL1 in TRAMP-C2 cells represses tumor establishment and in situ invasion. In vitro, the main action of CXCL1 expression in TRAMP cells is associated with the perturbation of molecules linked to cell adhesion and migration thus explaining in vivo data. Other in vitro findings also suggest that signaling by CXCL1 might activate a secretory network limiting in vivo tumor growth by reinforcing senescence. Immunohistochemical staining of human PCa, BPH, and normal prostate biopsies strengthen our observations on the mouse model: when expressed, CXCL1 is limited to small areas with faint staining and PCa progression does not rely on CXCL1 expression.

CONCLUSION

We could speculate that CXCL1 overexpression acts as a suppressor of malignancy limiting the escape of tumor cells from the primary tumor and reinforcing growth arrest.

Upregulation of IL-6, IL-8 and CXCL-1 production in dermal fibroblasts by normal/malignant epithelial cells in vitro: Immunohistochemical and transcriptomic analyses

BACKGROUND INFORMATION

Considering an analogy between wound healing and tumour progression, we studied chemokine and cytokine transcription and expression in normal fibroblasts by co-culture and in situ.

RESULTS

Whole-genome transcriptome profiling revealed strong upregulation for the interleukin (IL)-6, IL-8 and the chemokine CXCL-1 in in vitro co-cultures of normal fibroblasts with either normal or malignant epithelial cells compared to fibroblast cultures. The same ILs/chemokines were distinctly upregulated in clinical samples of squamous cell carcinoma when compared with paired normal mucosae. Analysis of culture supernatants showed that during the course of co-culture of the fibroblasts with the epithelial cells, IL-6, IL-8 and CXCL-1 were secreted to the culture medium. Experiments with addition of any of the proteins to the culture medium supported the notion that these ILs/chemokines strongly contributed to maintenance of a low-differentiation phenotype of epithelial cells, evaluated by the detection of keratin-8. Simultaneous addition of all factors increased the extent of the effect. These studies were extended by experiments with epithelial cells, either cultured in medium conditioned by preceding use for malignant keratinocytes without and in the presence of normal or cancer-associated fibroblasts or medium containing antibodies against IL-6, IL-8 and CXCL-1.

CONCLUSIONS

Our results indicate an analogy between wound healing and tumour growth, support the importance of epithelial-mesenchymal interaction in this model system and establish a potential bio-inspired anticancer therapy.

Mesenchymal stem cells tune the development of monocyte-derived dendritic cells toward a myeloid-derived suppressive phenotype through growth-regulated oncogene chemokines

Mesenchymal stem/stromal cells (MSCs) are promising potential candidates for the treatment of immunological diseases because of their immunosuppressive functions. However, the molecular mechanisms that mediate MSCs' immunosuppressive activity remain elusive. In this article, we report for the first time, to our knowledge, that secreted growth-regulated oncogene (GRO) chemokines, specifically GRO-γ, in human MSC-conditioned media have an effect on the differentiation and the function of human monocyte-derived dendritic cells. The monocyte-derived dendritic cells were driven toward a myeloid-derived suppressor cell (MDSC)-like phenotype by the GRO chemokines. GRO-γ-treated MDSCs had a tolerogenic phenotype that was characterized by an increase in the secretion of IL-10 and IL-4, and a reduction in the production of IL-12 and IFN-γ. We have also shown that the mRNA expression levels of the arginase-1 and inducible NO synthase genes, which characterize MDSCs, were upregulated by GRO-γ-primed mouse bone marrow cells. In addition, the ability of GRO-γ-treated bone marrow-derived dendritic cells to stimulate the OVA-specific CD8(+) T (OT-1) cell proliferation and the cytokine production of IFN-γ and TNF-α were significantly decreased in vivo. Our findings allow a greater understanding of how MDSCs can be generated and offer new perspectives to exploit the potential of MDSCs for alternative approaches to treat chronic inflammation and autoimmunity, as well as for the prevention of transplant rejection.

G31P, an antagonist against CXC chemokine receptors 1 and 2, inhibits growth of human prostate cancer cells in nude mice

Prostate cancer is the most common malignancy in Western countries. Chemokine C-X-C motif receptor 1 (CXCR1) and CXCR2 play a key role in generation and regulation of CXC chemokine signaling. CXCR1 is a receptor for interleukin 8 (IL8), a pro-inflammatory chemokine, and CXCR1/2 are crucially involved in the prostate cancer development and progression. Thus, we generated a high-affinity human CXCR1/CXCR2 inhibitor, CXCL8 (3-72) K11R/G31P, named G31P, which is a synthetic derivative of the human cytokine, IL-8. In this study, we investigated the effects of G31P on regulation of prostate cancer cell growth in vitro and in nude mouse xenografts. Cell viability, adhesion, and wound healing assays were used to assess the effects of G31P on growth, adhesion, and migration of PC-3 human prostate cancer cells in vitro, respectively. Nude mouse xenografts and xenograft implantation assays were performed to determine the effect of G31P on PC-3 cells in vivo. Immunohistochemistry was used to detect gene expression, and fluorescence imaging was used to detect tumor volume and microvessel density in tumor xenografts. The data showed that G31P treatment significantly reduced PC-3 cell viability, adhesion and migration capacity in a dose-dependent manner (up to 100 ng/ml). Additionally, G31P treatment of nude mice suppressed the growth of orthotopically transplanted tumor xenografts. G31P also inhibited tumor tissue vascularization, which was associated with the decreased expression of vascular endothelial growth factor and nuclear transcription factor (NF)-κB in orthotopic xenograft tissues. This study provides evidence that G31P, a CXCR1/2 inhibitor, may effectively control prostate cancer.

CXCR2: a target for pancreatic cancer treatment?

INTRODUCTION

Pancreatic cancer, a leading cause of cancer deaths worldwide, is very aggressive and has minimally effective treatment options. For those who have no surgical options, medical treatments are limited. The chemokine receptor CXCR2 has become the subject of much interest recently because of multiple studies indicating its involvement in cancer and inflammatory conditions. Research now indicates that CXCR2 and its ligands are intimately involved in tumor regulation and growth and that inhibition of its function shows promising results in multiple cancer types, including pancreatic cancer.

AREAS COVERED

In this study, the authors review basic molecular and structural details of CXCR2, as well as the known functions of CXCR2 and several of its ligands in inflammation and cancer biology with specific attention to pancreatic cancer. Then the future possibilities and questions remaining for pharmacological intervention against CXCR2 in pancreatic cancer are explored.

EXPERT OPINION

Many current inhibitory strategies already exist for targeting CXCR2 in vitro as well as in vivo. Clinically speaking, CXCR2 is an exciting potential target for pancreatic cancer; however, CXCR2 is functionally important for multiple processes and therapeutic options would benefit from further work toward understanding of these roles as well as structural and target specificity.

Effect of Danshen aqueous extract on serum hs-CRP, IL-8, IL-10, TNF-α levels, and IL-10 mRNA, TNF-α mRNA expression levels, cerebral TGF-β1 positive expression level and its neuroprotective mechanisms in CIR rats

To observe the effects of Danshen aqueous extract (DSAE) on the cerebral tissue and nerve stem cells in cerebral ischemia reperfusion (CIR) rats. The model rats were prepared by occlusion of the middle cerebral artery for 2 h and then by reperfusion. They were randomly divided into five groups: a control group, an CIR group and three DSAE-treated groups. As compared with the sham control group, there was significant increase (P < 0.05, P < 0.01) in the serum high-sensitivity C-reactive protein (hs-CRP) and interleukin-8 (IL-8) levels, interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-α) levels, and IL-10 mRNA, TNF-α mRNA expression levels, function score, Infarct size, TUNEL + cell counts, cerebral transforming growth factor beta 1 (TGF-β1) positive expression and cerebral neuron specific enolase (NSE) levels, and decrease in fas-associated protein with death domain (FADD) and death-associated protein (Daxx) positive expression levels in the CIR group. Compared with CIR group, DSAE treatment dose-dependently significantly decreased serum hs-CRP, IL-8, IL-10, TNF-α levels, and IL-10 mRNA, TNF-α mRNA expression levels, function score, Infarct size, TUNEL + cell counts, cerebral TGF-β1 positive expression and cerebral NSE levels, and increase FADD and Daxx positive expression levels in the CIR + DSAE groups. Taken together, these results suggest that DSAE has a neuroprotective role in the CIR rats, which may be related to improvement of immunity function, proteins and genes expression.

A high-fat diet enhances proliferation of prostate cancer cells and activates MCP-1/CCR2 signaling

BACKGROUND

Dietary patterns including high-fat diet (HFD) and high-carbohydrate diet (HCD) play an important role in prostate cancer progression. However, which of these diets have the greatest effect on tumor progression and its underlying mechanisms remains unclear.

METHODS

We investigated the effects of different diets on prostate cancer cell growth and the relevant circulating factors including serum insulin, growth factors, and inflammatory cytokines using the in vivo and ex vivo model.

RESULTS

The tumor growth of prostate cancer LNCaP xenograft was significantly higher in the HFD group than in the HCD and control diet (CD) groups (P = 0.01; HFD vs. HCD, P = 0.025; HFD vs. CD, P = 0.003). The mean level of the serum monocyte chemoattractant protein-1 (MCP-1) in the HFD group was significantly higher than that in the HCD and CD groups (P = 0.024; HFD vs. HCD, P = 0.033; HFD vs. CD, P = 0.001). The mRNA levels of CC chemokine receptor 2 (CCR2), which is an MCP-1 receptor, and the expression of activated Akt were the highest in the HFD group. Furthermore, serum from HFD-fed mice enhanced the proliferation of two PCa cells and CCR2 knockdown inhibited HFD-induced proliferation of LNCaP cells.

CONCLUSIONS

An HFD enhanced prostate cancer cell growth more strongly than an HCD or CD. MCP-1/CCR2 signaling may be involved in an HFD-induced prostate cancer progression.

Targeting PPARγ Signaling Cascade for the Prevention and Treatment of Prostate Cancer

The peroxisome proliferator-activated receptor-gamma (PPARγ) is a member of the hormone-activated nuclear receptor superfamily. PPARγ can be activated by a diverse group of agents, such as endogenous polyunsaturated fatty acids, 15-deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂), and thiazolidinedione (TZD) drugs. PPARγ induces antiproliferative, antiangiogenic, and prodifferentiation pathways in several tissue types, thus making it a highly useful target for downregulation of carcinogenesis. These TZD-derived novel therapeutic agents, alone or in combination with other anticancer drugs, have translational relevance in fostering effective strategies for cancer treatment. TZDs have been proven for antitumor activity in a wide variety of experimental cancer models, both in vitro and in vivo, by affecting the cell cycle, inducing cell differentiation and apoptosis, as well as by inhibiting tumor angiogenesis. Angiogenesis inhibition mechanisms of TZDs include direct inhibition of endothelial cell proliferation and migration, as well as reduction in tumor cell vascular endothelial growth factor production. In prostate cancer, PPARγ ligands such as troglitazone and 15d-PGJ₂ have also shown to inhibit tumor growth. This paper will focus on current discoveries in PPARγ activation, targeting prostate carcinogenesis as well as the role of PPARγ as a possible anticancer therapeutic option. Here, we review PPARγ as an antitumor agent and summarize the antineoplastic effects of PPARγ agonists in prostate cancer.

Well-defined degradable cationic polylactide as nanocarrier for the delivery of siRNA to silence angiogenesis in prostate cancer

Well-defined tertiary amine-functionalized cationic polylactides (CPLAs) are synthesized by thiol-ene click functionalization of an allyl-functionalized polylactide, and utilized for the delivery of interleukin-8 (IL-8) siRNA via CPLA-IL-8 siRNA nanoplexes. The CPLAs possess remarkable hydrolytic degradability, and their cytotoxicity is relatively low. The CPLA-IL-8 siRNA nanoplexes can be readily taken up by prostate cancer cells, resulting in significant IL-8 gene silencing. It is found that the degradability and cytotoxicity of CPLAs, as well as the transfection efficiency of the CPLA-IL-8 siRNA nanoplexes, positively correlate with the amine mol% of CPLAs.

Pathogenesis of prostatic small cell carcinoma involves the inactivation of the P53 pathway

Small cell neuroendocrine carcinoma (SCNC) of the prostate is a variant form of prostate cancer that occurs de novo or as a recurrent tumor in patients who received hormonal therapy for prostatic adenocarcinoma. It is composed of pure neuroendocrine (NE) tumor cells, but unlike the scattered NE cells in benign prostate and adenocarcinoma that are quiescent, the NE cells in SCNC are highly proliferative and aggressive, causing death in months. In this study, we provide evidence that interleukin 8 (IL8)-CXCR2-P53 (TP53) signaling pathway keeps the NE cells of benign prostate and adenocarcinoma in a quiescent state normally. While P53 appears to be wild-type in the NE cells of benign prostate and adenocarcinoma, immunohistochemical studies show that the majority of the NE tumor cells in SCNC are positive for nuclear p53, suggesting that the p53 is mutated. This observation is confirmed by sequencing of genomic DNA showing p53 mutation in five of seven cases of SCNC. Our results support the hypothesis that p53 mutation leads to inactivation of the IL8-CXCR2-p53 signaling pathway, resulting in the loss of an important growth inhibitory mechanism and the hyper-proliferation of NE cells in SCNC. Therefore, we have identified potential cells of origin and a molecular target for prostatic SCNC that are very different from those of conventional adenocarcinoma, which explains SCNC's distinct biology and the clinical observation that it does not respond to hormonal therapy targeting androgen receptor signaling, which produces short-term therapeutic effects in nearly all patients with prostatic adenocarcinoma.

Inducible silencing of protein kinase D3 inhibits secretion of tumor-promoting factors in prostate cancer

Protein kinase D (PKD) acts as a major mediator of several signaling pathways related to cancer development. Aberrant PKD expression and activity have been shown in multiple cancers, and novel PKD inhibitors show promising anticancer activities. Despite these advances, the mechanisms through which PKD contributes to the pathogenesis of cancer remain unknown. Here, we establish a novel role for PKD3, the least studied member of the PKD family, in the regulation of prostate cancer cell growth and motility through modulation of secreted tumor-promoting factors. Using both a stable inducible knockdown cell model and a transient knockdown system using multiple siRNAs, we show that silencing of endogenous PKD3 significantly reduces prostate cancer cell proliferation, migration, and invasion. In addition, conditioned medium from PKD3-knockdown cells exhibits less migratory potential compared with that from control cells. Further analysis indicated that depletion of PKD3 blocks secretion of multiple key tumor-promoting factors including matrix metalloproteinase (MMP)-9, interleukin (IL)-6, IL-8, and GROα but does not alter mRNA transcript levels for these factors, implying impairment of the secretory pathway. More significantly, inducible depletion of PKD3 in a subcutaneous xenograft model suppresses tumor growth and decreases levels of intratumoral GROα in mice. These data validate PKD3 as a promising therapeutic target in prostate cancer and shed light on the role of secreted tumor-promoting factors in prostate cancer progression.

High expression of CXCR2 is associated with tumorigenesis, progression, and prognosis of laryngeal squamous cell carcinoma

The laryngeal squamous cell carcinoma (LSCC) is one of the most common cancers threatening people's life. CXC-chemokine receptor type 2 (CXCR2) was reported to play critical roles in angiogenesis, tumorigenesis, and metastasis of several cancers such as colon cancer, melanoma, lung cancer, and so on. However, the expression of CXCR2 in LSCC and its association with clinical characters of LSCC remain unclear. Quantitative real-time reverse transcription-PCR and immunohistochemistry were used, respectively, to analyze the mRNA level and protein level of CXCR2 in 109 cases of LSCC tissues and 28 cases of tumor-adjacent normal tissues. The expression of CXCR2 in LSCC was significantly higher than that in tumor-adjacent tissues. Moreover, the expression level of CXCR2 protein in LSCC was significantly related to lymph node metastasis (P=.022), histopathological grade (P=.038), and 5 years' survival (P=.007). Cox regression analysis revealed that CXCR2 expression (P=.031), as well as lymphatic metastasis (P=.026) and TNM classification (P=.042), is an independent prognostic marker of LSCC. High expression of CXCR2 is also associated with short survival of LSCC patients. Our data indicate that the expression of CXCR2 is associated with the development and progression of LSCC. CXCR2 expression may serve as an independent prognostic marker for LSCC patients.

Recent advances in underlying pathologies provide insight into interleukin-8 expression-mediated inflammation and angiogenesis

Interleukin-8 has long been recognized to have anti-inflammatory activity, which has been established in various models of infection, inflammation, and cancer. Several cell types express the receptor for the cytokine IL-8 and upon its recognition produce molecules that are active both locally and systemically. Many different types of cells, in particular monocytes, neutrophils, epithelial, fibroblast, endothelial, mesothelial, and tumor cells, secrete IL-8. Increased expression of IL-8 and/or its receptors has been characterized in many chronic inflammatory conditions, including psoriasis, ARDS, COPD, and RA as well as many cancers, and its upregulation often correlates with disease activity. IL-8 constitutes the CXC class of chemokines, a potent chemoattractant and activator of neutrophils and other immune cells. It is a proangiogenic cytokine that is overexpressed in many human cancers. Therefore, inhibiting the effects of IL-8 signaling may be a significant therapeutic intervention.

A role for aberrantly expressed nuclear localized decorin in migration and invasion of dysplastic and malignant oral epithelial cells

Background

Oral cancer is the sixth most common malignancy worldwide with a mortality rate that is higher than many other cancers. Death usually occurs as a result of local invasion and regional lymph node metastases. Decorin is a multifunctional proteoglycan of the extracellular matrix that affects the biology of various types of cancer. Previously; we have shown that decorin is aberrantly expressed in the nucleus in human dysplastic oral keratinocytes (DOK) and malignant squamous cells carcinoma (SCC-25) and human biopsy tissues. In this study, we examined the role of nuclear decorin in oral cancer progression.

Materials and methods

We have used a post-transcriptional gene silencing (RNA interference) approach to stably knockdown nuclear decorin gene expression in DOK and SCC-25 cells using a specific shRNA plasmid and a combination of immunological and molecular techniques to study nuclear decorin function in these oral epithelial cell lines.

Results

More than 80% decorin silencing/knockdown was achieved as confirmed by real time PCR and western blot analysis in both DOK and SCC-25 cells. This RNA interference-mediated knockdown of nuclear decorin expression resulted in significantly reduced invasion and migration in these cell lines as measured by Matrigel™ coated and uncoated Trans well chamber assays respectively. Decorin silencing also resulted in reduced IL-8 mRNA and proteins levels in these cell lines. Culturing decorin silenced DOK and SCC-25 cells, with recombinant human IL-8 or IL-8 containing conditioned medium from respective un-transfected cells for 24 h prior to migration and invasion experiments, resulted in the salvation of reduced migration and invasion phenotype. Furthermore, we found that nuclear localized decorin interacts with EGFR in the nuclear fractions of both DOK and SCC-25 cells. Interestingly, EGFR (trans) activation has previously been shown to be involved in IL-8 production in various epithelia.

Conclusions

Taken together, our results indicate that nuclear localized decorin plays an important role in migration and invasion of oral cancer cells and thus may present as a novel potential target for the treatment of oral cancer.

Chemotaxis in cancer

Chemotaxis of tumour cells and stromal cells in the surrounding microenvironment is an essential component of tumour dissemination during progression and metastasis. This Review summarizes how chemotaxis directs the different behaviours of tumour cells and stromal cells in vivo, how molecular pathways regulate chemotaxis in tumour cells and how chemotaxis choreographs cell behaviour to shape the tumour microenvironment and to determine metastatic spread. The central importance of chemotaxis in cancer progression is highlighted by discussion of the use of chemotaxis as a prognostic marker, a treatment end point and a target of therapeutic intervention.

PEDF inhibits IL8 production in prostate cancer cells through PEDF receptor/phospholipase A2 and regulation of NFκB and PPARγ

Interleukin-8 (IL8/CXCL8) has been described as a key effector in prostate cancer progression and resistance to standard chemotherapeutic drugs. In the present study, we investigated the effect of the natural, angio-inhibitory and anti-tumoral Pigment Epithelium-Derived Factor (PEDF) on the expression of IL8 cytokine by prostate cancer cells. Using a cytokine antibody array and ELISA, in addition to IL8 quantitative RT PCR, we showed that PEDF inhibits the production of IL8 in human hormone-refractory prostate cancer cells, and delays the growth of these cells in vitro. IL8 reduction was mimicked in cancer cells treated with PPARγ agonist and NFκB-specific inhibitors. Accordingly, PPARγ expression increased in response to PEDF, whereas RelA/p65 expression and nuclear localization, and NFκB transcriptional activity decreased. NFκB deactivation was reversed by the PPARγ antagonist GW9662 and PPARγ (Leu(468)/Glu(471)) dominant negative suggesting a PPARγ-dependent process. We also investigated PEDF Receptor/PLA2 as key player in this pathway by small interference RNA. PEDFR knock down in prostate cancer cells reversed PEDF-induced PPARγ up-regulation, and NFκB and IL8 inhibition compared to non-targeting control siRNA. We conclude that by binding to PEDFR, PEDF up-regulates PPARγ, leading subsequently to suppressed NFκB-mediated transcriptional activation, reduced production of IL8 and limited proliferation of prostate cancer cells. These results reinforce PEDF's therapeutic potential and imply that blocking IL8 could represent a novel alternative for prostate cancer treatment.

Role of monocyte-lineage cells in prostate cancer cell invasion and tissue factor expression

BACKGROUND

Tissue factor (TF) is a cell surface glycoprotein intricately related to blood coagulation and inflammation. This study was performed to investigate the role of monocyte-lineage cells in prostate cancer cell TF expression and cell invasion.

METHODS

Prostate cancer cell invasion was tested with and without added peripheral blood monocytes or human monocyte-lineage cell lines. TF neutralizing antibodies were used to determine the TF requirement for prostate cancer cell invasion activity. Immunohistochemistry was performed to identify prostate tissue CD68 positive monocyte-derived cells and prostate epithelial TF expression.

RESULTS

Co-culture of PC-3, DU145, and LNCaP cells with isolated human monocytes significantly stimulated prostate cancer cell invasion activity. TF expression was greater in highly invasive prostate cancer cells and was induced in PC-3, DU145, and LNCaP cells by co-culture with U-937 cells, but not with THP-1 cells. TF neutralizing antibodies inhibited PC-3 cell invasion in co-cultures with monocyte-lineage U-937 or THP-1 cells. Prostate cancer tissues contained more CD68 positive cells in the stroma and epithelium (145 ± 53/mm(2)) than benign prostate (108 ± 31/mm(2)). Samples from advanced stage prostate cancer tended to contain more CD68 positive cells when compared with lower stage lesions. Prostatic adenocarcinoma demonstrated significantly increased TF expression compared with benign prostatic epithelium.

CONCLUSIONS

This study shows that co-culture with monocyte-lineage cells induced prostate cancer cell invasion activity. PC-3 invasion and TF expression was induced in co-culture with U-937 cells and partially inhibited with TF neutralizing antibodies.

CCR9 mediates PI3K/AKT-dependent antiapoptotic signals in prostate cancer cells and inhibition of CCR9-CCL25 interaction enhances the cytotoxic effects of etoposide

Despite recent advances in treatment and management of prostate cancer (PCa), it remains the second leading cause of cancer-related deaths among men in the US. Chemotherapy is one of the treatment alternatives for hormone refractory metastatic PCa. However, current chemotherapeutic regimens provide palliative benefit but relatively modest survival advantage primarily due to chemo-resistance and upregulated antiapoptotic machineries in PCa cells. Therefore, blocking the mechanisms responsible for suppression of apoptosis might improve current chemotherapeutic regimens. In this study, we show that CC chemokine receptor-9 (CCR9) and its natural ligand CCL25 interaction upregulates antiapoptotic proteins (i.e., PI3K, AKT, ERK1/2 and GSK-3beta) and downregulate activation of caspase-3 in PCa cells. Significant downregulation of these CCR9-mediated antiapoptotic proteins in the presence of a PI3K inhibitor (wortmannin), further suggests that the antiapoptotic action of CCR9 is primarily regulated through PI3K. Furthermore, the cytotoxic effect of etoposide was significantly inhibited in the presence of CCL25, and this inhibitory effect of CCL25 was abrogated when CCR9-CCL25 interaction was blocked using anti-CCR9 monoclonal antibodies. In conformation to these in vitro studies, significant reduction in tumor burden was found in mice receiving CCL25 neutralizing antibodies and etoposide together as compared to both as a single agent. These results suggest that the CCR9-CCL25 axis mediates PI3K/AKT-dependent antiapoptotic signals in PCa cells and could be a possible reason for low apoptosis and modest chemotherapeutic response. Therefore, targeting CCR9-CCL25 axis with cytotoxic agents may provide better therapeutic outcomes than using cytotoxic agents alone.

The role of the tissue microenvironment in the regulation of cancer cell motility and invasion

During malignant neoplastic progression the cells undergo genetic and epigenetic cancer-specific alterations that finally lead to a loss of tissue homeostasis and restructuring of the microenvironment. The invasion of cancer cells through connective tissue is a crucial prerequisite for metastasis formation. Although cell invasion is foremost a mechanical process, cancer research has focused largely on gene regulation and signaling that underlie uncontrolled cell growth. More recently, the genes and signals involved in the invasion and transendothelial migration of cancer cells, such as the role of adhesion molecules and matrix degrading enzymes, have become the focus of research. In this review we discuss how the structural and biomechanical properties of extracellular matrix and surrounding cells such as endothelial cells influence cancer cell motility and invasion. We conclude that the microenvironment is a critical determinant of the migration strategy and the efficiency of cancer cell invasion.

CXCR2 promotes ovarian cancer growth through dysregulated cell cycle, diminished apoptosis, and enhanced angiogenesis

PURPOSE

Chemokine receptor CXCR2 is associated with malignancy in several cancer models; however, the mechanisms involved in CXCR2-mediated tumor growth remain elusive. Here, we investigated the role of CXCR2 in human ovarian cancer.

EXPERIMENTAL DESIGN

CXCR2 expression was silenced by stable small hairpin RNA in ovarian cancer cell lines T29Gro-1, T29H, and SKOV3. Western blotting, immunofluorescence, enzyme-linked immunosorbent assay, flow cytometry, electrophoretic mobility shift assay, and mouse assay were used to detect CXCR2, interleukin-8, Gro-1, cell cycle, apoptosis, DNA binding of NF-kappaB, and tumor growth. Immunohistochemical staining of CXCR2 was done in 240 high-grade serous ovarian carcinoma samples.

RESULTS

Knockdown of CXCR2 expression by small hairpin RNA reduced tumorigenesis of ovarian cancer cells in nude mice. CXCR2 promoted cell cycle progression by modulating cell cycle regulatory proteins, including p21 (waf1/cip1), cyclin D1, CDK6, CDK4, cyclin A, and cyclin B1. CXCR2 inhibited cellular apoptosis by suppressing phosphorylated p53, Puma, and Bcl-xS; suppressing poly(ADP-ribose) polymerase cleavage; and activating Bcl-xL and Bcl-2. CXCR2 stimulated angiogenesis by increasing levels of vascular endothelial growth factor and decreasing levels of thrombospondin-1, a process likely involving mitogen-activated protein kinase, and NF-kappaB. Overexpression of CXCR2 in high-grade serous ovarian carcinomas was an independent prognostic factor of poor overall survival (P < 0.001) and of early relapse (P = 0.003) in the univariate analysis.

CONCLUSIONS

Our data provide strong evidence that CXCR2 regulates the cell cycle, apoptosis, and angiogenesis through multiple signaling pathways, including mitogen-activated protein kinase and NF-kappaB, in ovarian cancer. CXCR2 thus has potential as a therapeutic target and for use in ovarian cancer diagnosis and prognosis.

Deregulation of HIF1-alpha and hypoxia-regulated pathways in hepatocellular carcinoma and corresponding non-malignant liver tissue--influence of a modulated host stroma on the prognosis of HCC

PURPOSE

The aim of this study was to elucidate the role of HIF1A expression in hepatocellular carcinoma (HCC) and the corresponding non-malignant liver tissue and to correlate it with the clinical outcome of HCC patients after curative liver resection.

METHODS

HIF1A expression was determined by quantitative RT-PCR in HCC and corresponding non-malignant liver tissue of 53 patients surgically treated for HCC. High-density gene expression analysis and pathway analysis was performed on a selected subset of patients with high and low HIF1A expression in the non-malignant liver tissue.

RESULTS

HIF1A over-expression in the apparently non-malignant liver tissue was a predictor of tumor recurrence and survival. The estimated 1-year and 5-year disease-free survival was significantly better in patients with low HIF1A expression in the non-malignant liver tissue when compared to those patients with high HIF1 expression (88.9% vs. 67.9% and 61.0% vs. 22.6%, respectively, p = 0.008). Based on molecular pathway analysis utilizing high-density gene-expression profiling, HIF1A related molecular networks were identified that contained genes involved in cell migration, cell homing, and cell-cell interaction.

CONCLUSION

Our study identified a potential novel mechanism contributing to prognosis of HCC. The deregulation of HIF1A and its related pathways in the apparently non-malignant liver tissue provides for a modulated environment that potentially enhances or allows for HCC recurrence after curative resection.

CXC receptor-1 silencing inhibits androgen-independent prostate cancer

The CXC receptor-1 (CXCR1) is a coreceptor for interleukin-8 (IL-8) and is expressed on both normal and tumor cells. The function of CXCR1 in prostate cancer was investigated by silencing its expression, using RNA interference. We established stable cell colonies of PC-3 cells, depleted of CXCR1, using lentiviral plasmids (pLK0.1puro) generating small hairpin RNA (shRNA) against CXCR1 mRNA. Stable shRNA transfectants (PLK1-PLK5) that express significantly reduced CXCR1 mRNA (>or=90% down) and protein (>or=43% down) or vector-only transfectants (PC-3V) were characterized. PLK cells showed reduced cell proliferation (down, >or=66%), due to cell cycle arrest at G(1)-S phase, decreases in Cyclin D1, CDK4, phosphorylated Rb, and extracellular signal-regulated kinase 1/2 levels compared with those in PC-3V cells. CXCR1 depletion lead to increases in spontaneous apoptosis by mitochondria-mediated intrinsic mechanism and increases in proapoptotic proteins (BAD, 40%; BAX, 12%), but decreases in antiapoptotic proteins (BCL2, down 38%; BCL(xL), 20%). PLK2 cells grew as slow-growing tumors (decrease of 54%), compared with that of PC3V tumors in athymic mice. Ex vivo analyses of PLK2 tumor tissues showed reduced expression of Cyclin D1 and vascular endothelial growth factor, and increased apoptosis activity. Other IL-8-expressing prostate cancer cell lines also exhibited similar phenotypes when CXCR1 was depleted by CXCR1 shRNA transfection. In contrast to these cells, CXCR1 depletion had little effect on IL-8 ligand-deficient LNCaP cells. RNA interference rescue using mutated CXCR1 plasmids reversed the silencing effect of PLK2, thus demonstrating the specificity of phenotypic alteration by CXCR1 shRNA. These studies establish that CXCR1 promotes IL-8-mediated tumor growth.

Functional activity of CXCL8 receptors, CXCR1 and CXCR2, on human malignant melanoma progression

We examined the autocrine/paracrine role of interleukin-8 (CXCL8) and the functional significance of CXCL8 receptors, CXCR1 and CXCR2, in human malignant melanoma proliferation, migration, invasion and angiogenesis. We found that a panel of seven cell lines, even though at different extent, secreted CXCL8 protein, and expressed CXCR1 and CXCR2 independently from the CXCL8 expression, but depending on the oxygen level. In fact, hypoxic exposure increases the expression of CXCR1 and CXCR2. The cell proliferation of both M20 and A375SM lines, expressing similar levels of both CXCR1 and CXCR2 but secreting low and high amounts of CXCL8, respectively, was significantly enhanced by CXCL8 exposure and reduced by CXCL8, CXCR1 and CXCR2 neutralising antibodies, indicating the autocrine/paracrine role of CXCL8 in melanoma cell proliferation. Moreover, an increased invasion and migration in response to CXCL8 was observed in several cell lines, and a further enhancement evidenced under hypoxic conditions. A CXCL8-dependent in vivo vessel formation, evaluated through a matrigel assay, was also demonstrated. Furthermore, when neutralising antibodies against CXCR1 or CXCR2 were used, only the involvement of CXCR2, but not CXCR1 was observed on cell migration and invasion, while both receptors played a role in angiogenesis. In summary, our data demonstrate that CXCL8 induces cell proliferation and angiogenesis through both receptors and that CXCR2 plays an important role in regulating the CXCL8-mediated invasive and migratory behaviour of human melanoma cells. Thus, blocking the CXCL8 signalling axis promises an improvement for the therapy of cancer and, in particular, of metastatic melanoma.

Monocyte chemotactic protein 1 promotes lung cancer-induced bone resorptive lesions in vivo

Lung cancer is the leading cause of cancer-related deaths. The morbidity and mortality of lung cancer have markedly increased in the past decade with at least 75% of patients with lung cancer having evidence of metastases at the time of diagnosis. It frequently metastasizes to bone resulting in osteolytic lesions with unknown mechanisms. The aim of this study was to identify factors that mediate lung cancer-induced osteoclast activity in vivo. Using a human cytokine antibody array, we first determined cytokine levels in a conditioned medium collected from non-small cell lung cancer A549 and H1299 cells and the non-neoplastic human bronchial epithelial BEAS2B cells. Both A549 and H1229 cells produced significantly higher amount of several cytokines including monocyte chemotactic protein 1 (MCP-1) and interleukin 8 (IL-8) compared with BEAS2B cells. These findings were confirmed by ELISA. From clinical serum specimens, we also observed that MCP-1 and IL-8 levels were increased in lung cancer patients with bone metastases compared with the patients with localized tumor. Next, we investigated the effects of MCP-1 on osteoclast formation in vitro using murine bone marrow-derived monocytes. A549 conditioned medium induced osteoclast formation that was inhibited by neutralizing antibodies against MCP-1. Finally, A549 cells were stably transfected with MCP-1 short hairpin RNA. The MCP-1 knockdown A549 cells were implanted into the tibia of severe combined immunodeficient mice for 4 weeks. The MCP-1 knockdown significantly diminished A549 cell growth. We conclude that MCP-1 promotes lung cancer-induced osteoclast activity and thus bone resorptive lesions in vivo.