A growth-related oncogene/CXC chemokine receptor 2 autocrine loop contributes to cellular proliferation in esophageal cancer

Epithelial-mesenchymal transition induced by senescent fibroblasts

Depending on the cell type and tissue environment, epithelial and mesenchymal cell phenotypes are not static and can be highly dynamic. Epithelial-mesenchymal transitions (EMTs) and reverse EMTs provide flexibility during embryogenesis. While EMTs are a critical normal process during development and wound healing, properties of the EMT have been implicated in human pathology, particularly cancer metastasis. A normal undamaged epithelium does not typically exhibit features of an EMT. However, particularly under the influence of the surrounding microenvironment, cancer cells may reactivate developmental phenotypes out of context in the adult. This reactivation, such as the EMT, can facilitate tumor cell invasion and metastasis, and therefore is a major mechanism of tumor progression. Conversely, cellular senescence, which is associated with aging, is a process by which cells enter a state of permanent cell cycle arrest, thereby constituting a potent tumor suppressive mechanism. However, accumulating evidence shows that senescent cells can have deleterious effects on the tissue microenvironment. The most significant of these effects is the acquisition of a senescence-associated secretory phenotype (SASP) that turns senescent fibroblasts into pro-inflammatory cells having the ability to promote tumor progression, in part by inducing an EMT in nearby epithelial cells. Here, we summarize the potential impacts of SASP factors, particularly interleukins, on tissue microenvironments and their ability to stimulate tumor progression through induction of an EMT.

The role of CXCR2 chemokine receptors in the oral squamous cell carcinoma

This study evaluated the relevance of CXCR2 chemokine receptors in oral squamous cell carcinoma, by means of in vitro and in vivo approaches. The in vitro incubation of the selective and non-peptide CXCR2 receptor antagonist N-(2-hydroxy-4-nitrophenyl)-N9-(2-bromophenyl) Urea (SB225002; 25 to 800 nM) produced a time- and concentration-dependent inhibition of SCC158 (rat) and HN30 (human) cell lines viability. Conversely, this antagonist did not significantly affect the viability of the immortalized keratinocyte lineage, HaCaT. Additionally, the incubation of human IL-8 and rat CINC-1 CXCR2 agonists produced a concentration-related increase on HN30 and SCC158 proliferation. The submucosal injection of SCC158 cells (5 × 10(6) cells) into the tongue of Fischer 344 rats induced tumor development, which displayed typical clinical features. Immunohistochemical analysis of rat tongue biopsies revealed a marked increase of CXCR2 receptor immunoreactivity, which was accompanied by augumented expression of VEGF and caspase-3. Our data suggests an important role for CXCR2 receptors in oral squamous cell carcinoma.

Clinical significance of serum expression of GROβ in esophageal squamous cell carcinoma

AIM: To determine the association between serum levels of growth-related gene product β (GROβ) and clinical parameters in esophageal squamous cell carcinoma (ESCC).

METHODS: Using enzyme-linked immunosorbent assay, serum GROβ levels were measured in ESCC patients (n = 72) and healthy volunteers (n = 83). The association between serum levels of GROβ and clinical parameters of ESCC was analyzed statistically.

RESULTS: The serum GROβ levels were much higher in ESCC patients than in healthy controls (median: 645 ng/L vs 269 ng/L, P < 0.05). Serum GROβ levels were correlated positively with tumor size, lymph node metastasis, and tumor-node-metastasis (TNM) staging, but not with gender or the histological grade of tumors in ESCC patients. The sensitivity and specificity of the assay for serum GROβ were 73.61% and 56.63%, respectively.

CONCLUSION: GROβ may function as an oncogene product and contribute to tumorigenesis and metastasis of ESCC.

Chemokines in cancer related inflammation

Chemokines are key players of the cancer-related inflammation. Chemokine ligands and receptors are downstream of genetic events that cause neoplastic transformation and are abundantly expressed in chronic inflammatory conditions which predispose to cancer. Components of the chemokine system affect multiple pathways of tumor progression including: leukocyte recruitment, neo-angiogenesis, tumor cell proliferation and survival, invasion and metastasis. Evidence in pre-clinical and clinical settings suggests that the chemokine system represents a valuable target for the development of innovative therapeutic strategies.

Thrombin stimulates RPE cell motility by PKC-zeta- and NF-kappaB-dependent gene expression of MCP-1 and CINC-1/GRO chemokines

Retinal pigment epithelial cells (RPE) are the major cell type involved in the pathogenesis of proliferative vitreoretinopathy (PVR), which involves the epithelial-mesenchymal transition, proliferation, and directional migration of transformed RPE cells to the vitreous upon RPE exposure to serum components, thrombin among them. Although the aqueous humor and vitreous of PVR patients contain high levels of chemokines, their possible involvement in PVR development has not been explored. We here analyzed the effect of thrombin on chemokine gene expression and its correlation with RPE cell migration using rat RPE cells in culture as a model system. We demonstrated that thrombin induces RPE cell migration through the dose-dependent stimulation of MCP1 and GRO expression/release, and the autocrine activation of CXCR-2 and CCR-2 chemokine receptors. Whereas inhibition of CXCR2 by Sb-225002 and of CCR2 by Rs-504393 partially prevented hirudin-sensitive cell migration, the joint inhibition of these receptors abolished thrombin effect, suggesting the contribution of distinct but coincident mechanisms. Thrombin effects were not modified by Ro-32-0432 inhibition of conventional/novel PKC isoenzymes or by the MAPkinase pathway inhibitor U0126. MCP1 and GRO expression/secretion, and cell migration were completely prevented by the inhibitory PKC-zeta pseudosubstrate and by the nuclear factor-kappa B (NF-kappaB) inhibitor BAY11-7082, but not by wortmannin inhibition of PI3K. Results show that signaling pathways leading to RPE cell migration differ from the MEK-ERK-PI3K-mediated promotion RPE of cell proliferation, both of which concur at the activation of PKC-zeta.

Targeting NF-kappaB for colorectal cancer

IMPORTANCE OF THE FIELD

Colorectal cancer (CRC) is the second leading cause of cancer death. Progress has been made in the development of chemotherapy for advanced CRC. Targeted therapies against VEGF or EGFR are now commonly used. Many cases show that tolerance develops to such treatments and thus new strategies are required to replace or complement current therapies. The NF-kappaB signaling pathway plays critical roles in physiological and pathological processes, and the relationship between colon cancer development and NF-kappaB is becoming clear.

AREAS COVERED IN THIS REVIEW

We discuss evidence for the participation of activated NF-kappaB in carcinogenesis and consider the possibility of NF-kappaB being a target for CRC treatment.

WHAT THE READER WILL GAIN

NF-kappaB activation might be involved in development of not only colitis-associated cancer, but also sporadic CRC. NF-kappaB activation is associated with hallmarks of cancer. Constitutive NF-kappaB activation is frequently observed in CRC and is associated with angiogenesis and resistance to chemotherapy. Several NF-kappaB inhibitors have proven to be useful.

TAKE HOME MESSAGE

Induction of NF-kappaB activation leads to resistance to chemotherapy and constitutively activated NF-kappaB can often be seen in CRC. Anti-NF-kappaB therapy may rescue many cases of CRC and should be examined further for use as a therapy target.

Endogenous latent membrane protein 1 in Epstein-Barr virus-infected nasopharyngeal carcinoma cells attracts T lymphocytes through upregulation of multiple chemokines

Tumor-infiltrating T lymphocytes are considered to facilitate development of Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC), but how EBV in NPC tumor cells directs T cell infiltration remains unclear. Here we compare EBV-infected NPC cells with and without spontaneous expression of viral latent membrane protein 1 (LMP1) and find that culture supernatants of LMP1-positive NPC cells exert enhanced chemoattraction to primary T cells. Knockdown of endogenous LMP1 in the cells suppresses the chemotactic activity. Endogenous LMP1 in NPC cells upregulates multiple chemokines, among which MIP-1alpha, MIP-1beta and IL-8 contribute to T cell chemotaxis. We further reveal that LMP1-induced production of MIP-1alpha and MIP-1beta in NPC cells requires not only two carboxyl-terminal activation regions of LMP1 but also their downstream NF-kappaB and JNK pathways. This study corroborates that endogenous LMP1 in EBV-infected NPC cells induces multiple chemokines to promote T cell recruitment and perhaps other pathogenic events in NPC.

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.

Helicobacter pylori-derived Heat shock protein 60 enhances angiogenesis via a CXCR2-mediated signaling pathway

Helicobacter pylori is a potent carcinogen associated with gastric cancer malignancy. Recently, H. pylori Heat shock protein 60 (HpHSP60) has been reported to promote cancer development by inducing chronic inflammation and promoting tumor cell migration. This study demonstrates a role for HpHSP60 in angiogenesis, a necessary precursor to tumor growth. We showed that HpHSP60 enhanced cell migration and tube formation, but not cell proliferation, in human umbilical vein endothelial cells (HUVECs). HpHSP60 also indirectly promoted HUVEC proliferation when HUVECs were co-cultured with supernatants collected from HpHSP60-treated AGS or THP-1 cells. The angiogenic array showed that HpHSP60 dramatically induced THP-1 cells and HUVECs to produce the chemotactic factors IL-8 and GRO. Inhibition of CXCR2, the receptor for IL-8 and GRO, or downstream PLCbeta2/Ca2+-mediated signaling, significantly abolished HpHSP60-induced tube formation. In contrast, suppression of MAP K or PI3 K signaling did not affect HpHSP60-mediated tubulogenesis. These data suggest that HpHSP60 enhances angiogenesis via CXCR2/PLCbeta2/Ca2+ signal transduction in endothelial cells.

Significance of STMN1 expression in esophageal squamous cell carcinoma

AIM: To investigate the expression of Stathmin 1 (STMN1) protein in esophageal squamous cell carcinoma (ESCC) tissue and cell lines and to evaluate its correlation with the clinicopathologic parameters of ESCC.

METHODS: One-dimensional (1-D) Western blot was performed to determine the expression of STMN1 in 8 ESCC cell lines. Two-dimensional (2-D) Western blot was used to determine modified STMN1 in KYSE180 cells. Western blot and immunohistochemistry (IHC) were employed to determine the expression of STMN1 in ESCC specimens. The chi-square test was used to analyze IHC results.

RESULTS: STMN1 was widely expressed in ESCC cells, including WHCO1, EC0156, KYSE510, KYSE180, KYSE170, KYSE150, KYSE140 and KYSE30 cell lines. Two STMN1 protein spots were detected in KYSE180 cells on 2-D Western blot: one stronger signal and one weaker signal located in more basic area, which suggests that STMN1 protein may be modified in KYSE180 cells. Western blot analysis showed that STMN1 was overexpressed in 69.2% (9/13) of ESCC specimens compared with their normal epithelial counterparts. IHC assay also demonstrated that the positive rate of STMN1 expression was significantly higher in ESCC tissue than in matched adjacent normal tissue (P < 0.05). STMN1 expression is not correlated with age, gender, differentiation, tumor grade and lymph node metastasis.

CONCLUSION: The expression of STMN1 protein is up-regulated in both ESCC tissue and cell lines and may be modified in some ESCC cell lines. STMN1 might exert an oncogenic function in ESCC. Dynamic measurement of STMN1 expression level might aid to evaluate the progression of ESCC.

Activation of NF-kappaB signaling by inhibitor of NF-kappaB kinase beta increases aggressiveness of ovarian cancer

The NF-kappaB family of transcription factors has been implicated in the propagation of ovarian cancer, but the significance of constitutive NF-kappaB signaling in ovarian cancer is unknown. We hypothesized that constitutive NF-kappaB signaling defines a subset of ovarian cancer susceptible to therapeutic targeting of this pathway. We investigated the biological relevance of NF-kappaB in ovarian cancer using a small-molecule inhibitor of inhibitor of NF-kappaB kinase beta (IKKbeta) and confirmed with RNA interference toward IKKbeta. We developed a gene expression signature of IKKbeta signaling in ovarian cancer using both pharmacologic and genetic manipulation of IKKbeta. The expression of IKKbeta protein itself and the nine-gene ovarian cancer-specific IKKbeta signature were related to poor outcome in independently collected sets of primary ovarian cancers (P = 0.02). IKKbeta signaling in ovarian cancer regulated the transcription of genes involved in a wide range of cellular effects known to increase the aggressive nature of the cells. We functionally validated the effect of IKKbeta signaling on proliferation, invasion, and adhesion. Downregulating IKKbeta activity, either by a small-molecule kinase inhibitor or by short hairpin RNA depletion of IKKbeta, blocked all of these cellular functions, reflecting the negative regulation of the target genes identified. The diversity of functions controlled by IKKbeta in ovarian cancer suggests that therapeutic blockade of this pathway could be efficacious if specific IKKbeta inhibitor therapy is focused to patients whose tumors express a molecular profile suggestive of dependence on IKKbeta activity.

Neutralizing endogenous chemokines with small molecules. Principles and potential therapeutic applications

Regulation of cellular responses to external stimuli such as hormones, neurotransmitters, or cytokines is achieved through the control of all steps of the complex cascade starting with synthesis, going through maturation steps, release, distribution, degradation and/or uptake of the signalling molecule interacting with the target protein. One possible way of regulation, referred to as scavenging or neutralization of the ligand, has been increasingly studied, especially for small protein ligands. It shows innovative potential in chemical biology approaches as well as in disease treatment. Neutralization of protein ligands, as for example cytokines or chemokines can lead to the validation of signalling pathways under physiological or pathophysiological conditions, and in certain cases, to the development of therapeutic molecules now used in autoimmune diseases, chronic inflammation and cancer treatment. This review explores the field of ligand neutralization and tries to determine to what extent small chemical molecules could substitute for neutralizing antibodies in therapeutic approaches.

CXC chemokine ligand 2 induced by receptor activator of NF-kappa B ligand enhances osteoclastogenesis

CXCL2 has been known to regulate immune functions mainly by chemo-attracting neutrophils. In this study, we show that CXCL2 can be induced by receptor activator of NF-kappaB ligand, the osteoclast (OC) differentiation factor, through JNK and NF-kappaB signaling pathways in OC precursor cells. CXCL2 in turn enhanced the proliferation of OC precursor cells of bone marrow-derived macrophages (BMMs) through the activation of ERK. Knockdown of CXCL2 inhibited both the proliferation of and the ERK activation in BMMs. During osteoclastogenesis CXCL2 stimulated the adhesion and the migration of BMMs. Moreover, the formation of OCs from BMMs was significantly increased on treatment with CXCL2. Conversely, the CXCL2 antagonist repertaxin and a CXCL2 neutralizing Ab potently reduced receptor activator of NF-kappaB ligand-induced osteoclastogenesis. Furthermore, CXCL2 evoked fulminant bone erosion in the in vivo mouse experiments. Finally, prominent upregulation of CXCL2 was detected in synovial fluids and sera from rheumatoid arthritis patients, suggesting a potential involvement of CXCL2-mediated osteoclastogenesis in rheumatoid arthritis-associated bone destruction. Thus, CXCL2 is a novel therapeutic target for inflammatory bone destructive diseases.

A human-like senescence-associated secretory phenotype is conserved in mouse cells dependent on physiological oxygen

Cellular senescence irreversibly arrests cell proliferation in response to oncogenic stimuli. Human cells develop a senescence-associated secretory phenotype (SASP), which increases the secretion of cytokines and other factors that alter the behavior of neighboring cells. We show here that “senescent” mouse fibroblasts, which arrested growth after repeated passage under standard culture conditions (20% oxygen), do not express a human-like SASP, and differ from similarly cultured human cells in other respects. However, when cultured in physiological (3%) oxygen and induced to senesce by radiation, mouse cells more closely resemble human cells, including expression of a robust SASP. We describe two new aspects of the human and mouse SASPs. First, cells from both species upregulated the expression and secretion of several matrix metalloproteinases, which comprise a conserved genomic cluster. Second, for both species, the ability to promote the growth of premalignant epithelial cells was due primarily to the conserved SASP factor CXCL-1/KC/GRO-α. Further, mouse fibroblasts made senescent in 3%, but not 20%, oxygen promoted epithelial tumorigenesis in mouse xenographs. Our findings underscore critical mouse-human differences in oxygen sensitivity, identify conditions to use mouse cells to model human cellular senescence, and reveal novel conserved features of the SASP.

The chemokine system in cancer biology and therapy

Chemokines are a key component of cancer-related inflammation. Chemokines and chemokine receptors are downstream of genetic events that cause neoplastic transformation and are components of chronic inflammatory conditions, which predispose to cancer. Components of the chemokine system affect in a cell autonomous or non-autonomous way multiple pathways of tumor progression, including: leukocyte recruitment and function; cellular senescence; tumor cell proliferation and survival; invasion and metastasis. Available information in preclinical and clinical settings suggests that the chemokine system represents a valuable target for the development of innovative therapeutic strategies.

Potential new urinary markers in the early detection of bladder cancer

PURPOSE OF REVIEW

Bladder cancer remains a highly prevalent and lethal malignancy. Early diagnosis and prompt treatment have been shown to improve survival at both initial diagnosis and recurrence. A vast number of tumor markers have been identified and rigorously evaluated in attempts to improve noninvasive diagnostic accuracy of bladder cancer. Hematuria was the first tumor marker in a field that has grown to include soluble markers, cell-surface antigens, cell-cycle-related proteins, and genetic alterations. We aim to provide a critical appraisal of newer markers and the current state of research.

RECENT FINDINGS

The number of tumor markers identified has been exponentially increasing. For a variety of reasons, many are unsuitable for clinical practice. More promising recent markers include those discovered in the fields of genomics, proteomics, and epigenetics. Much of the recent work is focused on molecular genetic pathways in bladder cancer.

SUMMARY

The field of bladder cancer tumor markers remains a rapidly evolving area in which newer markers are constantly identified, evaluated, and often discarded if they do not add significantly to the urologists' armamentarium. Newer markers rely on genetic rearrangements, molecular changes, and cell-cycle-related proteins. Work is currently being done to identify the most promising markers.

Inhibition of proliferation, invasion, and migration of prostate cancer cells by downregulating elongation factor-1alpha expression

Overexpression of elongation factor-1alpha (EF-1alpha) has been reported to contribute to the development and progression of various cancers. However, its role in prostate cancer (PCa) still remains poorly understood. In the present study, we investigate the influence of EF-1alpha in Du145, a high-grade metastatic PCa cell line, and demonstrate that EF-1alpha plays an essential role in cellular properties associated with tumor progression, namely cell proliferation, invasion, and migration. In this study, EF-1alpha expression in human PCa cell line Du145 was reduced by RNA interference (RNAi) technology, and the proliferation, invasion, and migration of EF-1alpha-reduced Du145 cells were examined. We also detected an EF-1alpha expression pattern in 20 pairs of primary PCa samples and their corresponding normal tissues. Expression of EF-1alpha was detectable in four PCa cell lines (22RV1, LnCap, Du145, and PC3), indicating its possible role in pathogenesis of PCa. RNAi-mediated knockdown of EF-1alpha expression in Du145 cells, which expressed the highest level of EF-1alpha among four PCa cell lines, led to a decrease in proliferation. Similarly, suppression of EF-1alpha inhibited Du145 cell migration and invasion through a basement membrane substitute. Furthermore, we found that the normal prostate tissues showed a relatively low level of EF-1alpha expression, whereas PCa tissues demonstrated significantly higher expression levels of EF-1alpha (P < 0.001). Taken together, these findings support the hypothesis that EF-1alpha affects multiple processes involved in tumor progression, and identify EF-1alpha as a potential therapeutic target.

The invasive potential of human melanoma cell lines correlates with their ability to alter fibroblast gene expression in vitro and the stromal microenvironment in vivo

The tumor microenvironment is thought to play an important role in invasion and metastasis. Previously, we have shown that signaling from melanoma cells can alter the gene expression profiles of fibroblasts in vitro and in vivo. To investigate whether the capacity to signal fibroblasts and alter host gene expression profiles is correlated to the invasive potential of specific human melanoma cell lines, we assayed changes in gene expression of fibroblasts when cocultured with the human melanoma cell lines BLM, MV3, A2058, SK-mel28 and WM164. Results indicated that the gene expression of key chemokines and cytokines, such as IL-1B, IL-8, IL-6 and CCL2/MCP1, was significantly upregulated in fibroblasts cocultured with the invasive melanoma lines BLM and MV3 compared to fibroblasts cocultured with noninvasive WM164 cells. The results were verified by quantitative RT-PCR as well as by protein assay and supported by immunohistochemistry of human invasive melanoma. Furthermore, a role for fibroblast-secreted IL-1B in the invasion of melanoma was demonstrated in vitro, where siRNA silencing of IL-1B in melanoma-stimulated fibroblasts resulted in a diminution of melanoma invasion. Although CCL2/MCP1, a chemoattractant for macrophages, was shown to be upregulated in fibroblasts cocultured with metastatic melanoma cell lines, immunohistochemical analysis of human melanoma also indicated CCL2/MCP1 production associated with the melanoma. In summary, these experiments indicate that the invasiveness of melanoma can partly be correlated to its ability to stimulate host stromal fibroblasts to give rise to the secretion of chemokines that generate a microenvironment that is conductive for melanoma invasion and metastasis.

Enhanced expression and clinical significance of chemokine receptor CXCR2 in hepatocellular carcinoma

BACKGROUND

An ELR+ CXC chemokine receptor, CXCR2, was recently reported to be involved in tumorigenesis and development. However, the role of CXCR2 in hepatocellular carcinoma (HCC) is poorly understood. In this study, we aimed to investigate the association between CXCR2 expression and the biocharacteristics of HCC, and determine whether the expression of CXCR2 was related to the tumorigenesis and progression.

METHODS

Forty-two patients who underwent hepatic resection and were diagnosed as HCC by histologic examination were included. HCC and corresponding adjacent tissues (distance from the tumor border exceeding 2 cm) were obtained. Twenty-three samples of normal liver tissue were acquired surgically from the patients who had received an operation due to liver trauma. CXCR2 mRNA and protein expressions were examined using semiquantitative reverse transcription-PCR and Western blot.

RESULTS

Expression levels of CXCR2 were significantly increased in HCC compared with adjacent and normal liver tissues (P < 0.05). The results showed that CXCR2 mRNA and protein expression levels were not related to age, gender, AFP levels, tumor capsule, or tumor size. Also, there was no relationship between CXCR2 mRNA expression and TNM staging. The expression levels of CXCR2 mRNA and protein were correlated with intrahepatic metastasis (P < 0.05), portal cancer embolus (P < 0.05), and low differentiation (P < 0.05). Furthermore, the protein level of CXCR2 was relevant to TNM staging. The protein level of CXCR2 in stage III-IV was remarkably higher than in stage I-II (P < 0.05).

CONCLUSION

Our data revealed that CXCR2 was able to promote invasion and metastasis of HCC. It may be a useful marker for judging biocharacteristics and prognosis of HCC.

Prostaglandin F2alpha-F-prostanoid receptor signaling promotes neutrophil chemotaxis via chemokine (C-X-C motif) ligand 1 in endometrial adenocarcinoma

The prostaglandin F(2alpha) (PGF(2alpha)) receptor (FP) is elevated in endometrial adenocarcinoma. This study found that PGF(2alpha) signaling via FP regulates expression of chemokine (C-X-C motif) ligand 1 (CXCL1) in endometrial adenocarcinoma cells. Expression of CXCL1 and its receptor, CXCR2, are elevated in cancer tissue compared with normal endometrium and localized to glandular epithelium, endothelium, and stroma. Treatment of Ishikawa cells stably transfected with the FP receptor (FPS cells) with 100 nmol/L PGF(2alpha) increased CXCL1 promoter activity, mRNA, and protein expression, and these effects were abolished by cotreatment of cells with FP antagonist or chemical inhibitors of Gq, epidermal growth factor receptor, and extracellular signal-regulated kinase. Similarly, CXCL1 was elevated in response to 100 nmol/L PGF(2alpha) in endometrial adenocarcinoma explant tissue. CXCL1 is a potent neutrophil chemoattractant. The expression of CXCR2 colocalized to neutrophils in endometrial adenocarcinoma and increased neutrophils were present in endometrial adenocarcinoma compared with normal endometrium. Conditioned media from PGF(2alpha)-treated FPS cells stimulated neutrophil chemotaxis, which could be abolished by CXCL1 protein immunoneutralization of the conditioned media or antagonism of CXCR2. Finally, xenograft tumors in nude mice arising from inoculation with FPS cells showed increased neutrophil infiltration compared with tumors arising from wild-type cells or following treatment of mice bearing FPS tumors with CXCL1-neutralizing antibody. In conclusion, our results show a novel PGF(2alpha)-FP pathway that may regulate the inflammatory microenvironment in endometrial adenocarcinoma via neutrophil chemotaxis.

A key role for early growth response-1 and nuclear factor-kappaB in mediating and maintaining GRO/CXCR2 proliferative signaling in esophageal cancer

Although early growth response-1 (EGR-1) has been shown as a key transcription factor in controlling cell growth, proliferation, differentiation, and angiogenesis, its role in the development of esophageal cancer is poorly understood despite the high frequency of this disease in many parts of the world. Here, immunohistochemistry showed that EGR-1 is overexpressed in 80% of esophageal tumor tissues examined. Furthermore, EGR-1 is constitutively expressed in all esophageal cancer cell lines analyzed. Esophageal squamous carcinoma WHCO1 cells stably transfected with EGR-1 short hairpin RNA displayed a 55% reduction in EGR-1 protein levels, 50% reduction in cell proliferation, a 50% reduction in cyclin-dependent kinase 4 levels, and a 2-fold induction in p27(Kip1) levels associated with a G(2)-M cell cycle arrest. EGR-1 knockdown also caused a marked induction in IkappaBalpha expression, an effect also observed in GRObeta RNA interference-expressing WHCO1 cells, because EGR-1 lies downstream of GRO/CXCR2 signaling. Furthermore, p65 mRNA levels were also reduced in cells treated with either short hairpin RNA EGR-1 or small interfering RNA EGR-1. Immunohistochemical analysis indicated that p65 is elevated in 78% (n = 61) of esophageal tumor sections analyzed. Moreover, nuclear factor-kappaB inhibition with either sodium salicylate or p65 RNA interference led to a significant reduction in GROalpha and GRObeta expression. These results indicate that EGR-1 and nuclear factor-kappaB mediate GRO/CXCR2 proliferative signaling in esophageal cancer and may represent potential target molecules for therapeutic intervention.

Role of eotaxin-1 signaling in ovarian cancer

PURPOSE

Tumor cell growth and migration can be directly regulated by chemokines. In the present study, the association of CCL11 with ovarian cancer has been investigated.

EXPERIMENTAL DESIGN AND RESULTS

Circulating levels of CCL11 in sera of patients with ovarian cancer were significantly lower than those in healthy women or women with breast, lung, liver, pancreatic, or colon cancer. Cultured ovarian carcinoma cells absorbed soluble CCL11, indicating that absorption by tumor cells could be responsible for the observed reduction of serum level of CCL11 in ovarian cancer. Postoperative CCL11 levels in women with ovarian cancer negatively correlated with relapse-free survival. Ovarian tumors overexpressed three known cognate receptors of CCL11, CC chemokine receptors (CCR) 2, 3, and 5. Strong positive correlation was observed between expression of individual receptors and tumor grade. CCL11 potently stimulated proliferation and migration/invasion of ovarian carcinoma cell lines, and these effects were inhibited by neutralizing antibodies against CCR2, CCR3, and CCR5. The growth-stimulatory effects of CCL11 were likely associated with activation of extracellular signal-regulated kinase 1/2, MEK1, and STAT3 phosphoproteins and with increased production of multiple cytokines, growth factors, and angiogenic factors. Inhibition of CCL11 signaling by the combination of neutralizing antibodies against the ligand and its receptors significantly increased sensitivity to cisplatin in ovarian carcinoma cells.

CONCLUSION

We conclude that CCL11 signaling plays an important role in proliferation and invasion of ovarian carcinoma cells and CCL11 pathway could be targeted for therapy in ovarian cancer. Furthermore, CCL11 could be used as a biomarker and a prognostic factor of relapse-free survival in ovarian cancer.

Identification of GRO1 as a critical determinant for mutant p53 gain of function

Mutant p53 gain of function contributes to cancer progression, increased invasion and metastasis potentials, and resistance to anticancer therapy. The ability of mutant p53 to acquire its gain of function is shown to correlate with increased expression of progrowth genes, such as c-MYC, MDR1, and NF-kappaB2. However, most of the published studies to identify mutant p53 target genes were performed in a cell system that artificially overexpresses mutant p53. Thus, it remains unclear whether such mutant p53 targets can be regulated by endogenous physiological levels of mutant p53. Here, we utilized SW480 and MIA-PaCa-2 cells, in which endogenous mutant p53 can be inducibly knocked down, to identify mutant p53 target genes that potentially mediate mutant p53 gain of function. We found that knockdown of mutant p53 inhibits GRO1 expression, whereas ectopic expression of mutant R175H in p53-null HCT116 cells increases GRO1 expression. In addition, we found that endogenous mutant p53 is capable of binding to and activating the GRO1 promoter. Interestingly, ectopic expression of GRO1 can rescue the proliferative defect in SW480 and MIA-PaCa-2 cells induced by knockdown of mutant p53. Conversely, knockdown of endogenous GRO1 inhibits cell proliferation and thus abrogates mutant p53 gain of function in SW480 cells. Taken together, our findings define a novel mechanism by which mutant p53 acquires its gain of function via transactivating the GRO1 gene in cancer cells. Thus, targeting GRO1 for cancer therapy would be applicable to a large portion of human tumors with mutant p53, but the exploration of GRO1 as a potential target should take the mutation status of p53 into consideration.

Chemokine C-X-C motif receptor 6 contributes to cell migration during hypoxia

The chemokine and chemokine receptor families have important roles in tumorigenesis. Although CXCR4 and CCR7 have been reported to be associated with cancer metastasis, the role of other chemokine receptors in cancer is poorly understood. We explored the status of CXCR6 in hypoxia-induced cell migration. Breast cancer cells and human umbilical vein endothelial cells (HUVEC) expressed CXCR6, and showed appreciable chemotactic migration to CXCL16. Significant accumulation of CXCR6 mRNA and protein during hypoxia was observed. Overexpression of CXCR6 increased cell migration, and knockdown of CXCR6 attenuated hypoxia-mediated cell migration and MMP-2 secretion. To investigate possible mechanisms regulating CXCR6 expression during hypoxia, we detected the expression of HIFs and found that HIF-1alpha was involved in CXCR6 regulation. CXCR6 and HIF-1alpha were highly expressed in breast cancer lymph nodes metastases. Our data suggest CXCR6 contributes significantly to cell migration during hypoxia.

The good and the bad of chemokines/chemokine receptors in melanoma

Chemokine ligand/receptor interactions affect melanoma cell growth, stimulate or inhibit angiogenesis, recruit leukocytes, promote metastasis, and alter the gene expression profile of the melanoma associated fibroblasts. Chemokine/chemokine receptor interactions can protect against tumor development/growth or can stimulate melanoma tumor progression, tumor growth and metastasis. Metastatic melanoma cells express chemokine receptors that play a major role in the specifying the organ site for metastasis, based upon receptor detection of the chemokine gradient elaborated by a specific organ/tissue. A therapeutic approach that utilizes the protective benefit of chemokines involves delivery of angiostatic chemokines or chemokines that stimulate the infiltration of cytotoxic T cells and natural killer T cells into the tumor microenvironment. An alternative approach that tackles the tumorigenic property of chemokines uses chemokine antibodies or chemokine receptor antagonists to target the growth and metastatic properties of these interactions. Based upon our current understanding of the role of chemokine-mediated inflammation in cancer, it is important that we learn to appropriately regulate the chemokine contribution to the tumorigenic 'cytokine/chemokine storm', and to metastasis.

Secreted CXCL1 is a potential mediator and marker of the tumor invasion of bladder cancer

PURPOSE

The purpose of this study was to identify proteins that are potentially involved in the tumor invasion of bladder cancer.

EXPERIMENTAL DESIGN

We searched for the candidate proteins by comparing the profiles of secreted proteins among the poorly invasive human bladder carcinoma cell line RT112 and the highly invasive cell line T24. The proteins isolated from cell culture supernatants were identified by shotgun proteomics. We found that CXCL1 is related to the tumor invasion of bladder cancer cells. We also evaluated whether the amount of the chemokine CXCL1 in the urine would be a potential marker for predicting the existence of invasive bladder tumors.

RESULTS

Higher amount of CXCL1 was secreted from highly invasive bladder carcinoma cell lines and this chemokine modulated the invasive ability of those cells in vitro. It was revealed that CXCL1 regulated the expression of matrix metalloproteinase-13 in vitro and higher expression of CXCL1 was associated with higher pathologic stages in bladder cancer in vivo. We also showed that urinary CXCL1 levels were significantly higher in patients with invasive bladder cancer (pT1-4) than those with noninvasive pTa tumors (P = 0.0028) and normal control (P < 0.0001). Finally, it was shown that CXCL1 was an independent factor for predicting the bladder cancer with invasive phenotype.

CONCLUSIONS

Our results suggest that CXCL1 modulates the invasive abilities of bladder cancer cells and this chemokine may be a potential candidate of urinary biomarker for invasive bladder cancer and a possible therapeutic target for preventing tumor invasion.

Enhanced ENA-78 and IL-8 expression in patients with malignant pancreatic diseases

BACKGROUND/AIM

Pancreatic cancer is characterized by perineural invasion, early lymph node and liver metastases, and an extremely dismal prognosis. In the present study we aimed at investigating the expression profile of pro-inflammatory and angiogenic CXC chemokines as potential factors contributing to the aggressive biology of this gastrointestinal malignancy.

METHODS

Protein expression profiles of the CXC chemokines growth-related oncogene alpha (GRO-alpha/CXCL1), epithelial cell-derived neutrophil-activating peptide-78 (ENA-78/CXCL5), granulocyte chemoattractant protein-2 (GCP-2/CXCL6), neutrophil-activating protein-2 (NAP-2/CXCL7), and interleukin-8 (IL-8/CXCL8) were assessed by enzyme-linked immunosorbent assay in pancreatic carcinoma, cancer of the papilla of Vater, pancreatic cystadenoma, and chronic pancreatitis specimens.

RESULTS

IL-8 and ENA-78 protein expression was most pronounced in pancreatic carcinoma specimens, showing an 11-fold and 17-fold overexpression in comparison with non-affected neighbouring tissues, a 66-fold and 24-fold upregulation compared to pancreatic cystadenoma, and a 6-fold and 9-fold overexpression with respect to chronic pancreatitis, respectively (p < 0.05 between all groups). In addition, a close correlation between IL-8 and ENA-78 protein expression and advanced pancreatic carcinomas in relation to the T category was evident (p < 0.05).

CONCLUSION

Our results demonstrate that ELR+ CXC chemokines are differentially expressed in malignant and non-malignant human pancreatic specimens, suggesting a potential contribution of these chemokines to the pathogenesis of pancreatic carcinoma.

Identification of truncated chemokine receptor 7 in human colorectal cancer unable to localize to the cell surface and unreactive to external ligands

Chemokine receptors are thought to be involved in the process of cancer metastases. When investigating cell lines and tissues from colorectal cancer (CRC), the CCR7 protein unexpectedly was confined to the cytoplasm and not present on the cell surface. This study investigated at the DNA, mRNA and protein level, the mechanism and the consequences of the failure of CCR7 to localize to the cell membrane. In all 15 CRC cell lines tested, no surface CCR7 was detected and no chemotactic response was elicited upon in-vitro exposure to CCR7 chemokine ligands (CCL) 19 and CCL21. Integrity of CCR7 DNA and mRNA was examined with respect to signal peptide expression in cell lines and CRC tissues by real-time RT-PCR and sequencing. Nine of 15 CRC cell lines and 8 of 14 CRC tissues revealed a truncated CCR7 mRNA species containing various incomplete signal peptide encoding sequences, while the corresponding DNA was intact. These results indicate in CRC frequent alternative splicing or post-transcriptional mRNA modification resulting in a CCR7 molecule lacking an intact signal peptide prohibiting membrane translocation. Further studies would be necessary to identify a potential intracellular role of the truncated CCR7, abundantly present in the cytoplasm.

Chemokines as therapeutic targets in renal cell carcinoma

Targeting novel pathways associated with tumor angiogenesis, invasion and immunity, may lead to improvement in patient outcomes for renal cell carcinoma. Chemokines potentiate tumor growth, metastasis, angiogenesis and immune evasion through interactions with stromal cells and neoplastic cells. Further understanding of the mechanisms involved in chemokine-mediated angiogenesis and metastasis may lead to improved therapeutic strategies in this disease. Interactions between chemokine expression and signaling, and the VEGF and hypoxia-inducible factor pathways offer important opportunities to intervene in the process of renal cell carcinoma proliferation, angiogenesis and invasion. Modulation of the CXCR3/CXCR3-ligand or the CXCR4/CXCL12 biologic axis may be potential therapeutic targets for the treatment of renal cell carcinoma. Furthermore, combination treatment with agents targeting chemokine signaling with therapies directed at angiogenesis and tumor immunity may lead to improved outcomes in this disease.

Epstein-Barr virus lytic transactivator Zta enhances chemotactic activity through induction of interleukin-8 in nasopharyngeal carcinoma cells

Epstein-Barr virus (EBV)-associated, undifferentiated type of nasopharyngeal carcinoma (NPC) is characterized by intensive leukocyte infiltration. Interaction between the infiltrating cells and the tumor cells has been considered crucial for NPC development. Recruitment of the infiltrates can be directed by certain chemokines present in the NPC tissues. It is unknown whether and how EBV lytic infection regulates expression of the chemokines. Using an antibody array, we first found that several chemokines secreted from EBV-infected NPC cells are increased upon EBV reactivation into the lytic cycle, and interleukin-8 (IL-8) is the chemokine upregulated most significantly and consistently. Further studies showed that the EBV lytic transactivator Zta is a potent inducer of IL-8 in NPC cells, augmenting secreted and intracellular IL-8 proteins, as well as IL-8 RNA. Zta upregulates Egr-1, a cellular transcription factor that has been involved in upregulation of IL-8, but the Zta-induced IL-8 expression is independent of Egr-1. The ability of Zta to transactivate the IL-8 promoter is important for the induction of IL-8, and we have identified two Zta-responsive elements in the promoter. Zta can bind to these two elements in vitro and can also be recruited to the IL-8 promoter in vivo. DNA-binding-defective Zta mutants can neither activate the IL-8 promoter nor induce IL-8 production. In addition, Zta-expressing NPC cells exert enhanced chemotactic activity that is mainly mediated by IL-8. Since IL-8 may contribute to not only leukocyte infiltration but also multiple oncogenic processes, the present study provides a potential link between EBV lytic infection and pathogenesis of NPC.

CXCR2 agonists in ADPKD liver cyst fluids promote cell proliferation

Autosomal dominant polycystic kidney disease (ADPKD) is a highly prevalent genetic disease that results in cyst formation in kidney and liver. Cytokines and growth factors secreted by the cyst-lining epithelia are positioned to initiate autocrine/paracrine signaling and promote cyst growth. Comparative analyses of human kidney and liver cyst fluids revealed disparate cytokine/growth factor profiles. CXCR2 agonists, including IL-8, epithelial neutrophil-activating peptide (ENA-78), growth-related oncogene-alpha (GRO-alpha), are potent proliferative agents that were found at high levels in liver but not kidney cyst fluids. Liver cysts are lined by epithelial cells derived from the intrahepatic bile duct (i.e., cholangiocytes). In polarized pkd2(WS25/-) mouse liver cyst epithelial monolayers, CXCR2 agonists were released both apically and basally, indicating that they may act both on the endothelial and epithelial cells within or lining the cyst wall. IL-8 and human liver cyst fluid induced cell proliferation of HMEC-1 cells, a human microvascular endothelial cell line, and Mz-ChA1 cells, a human cholangiocyte cell model. IL-8 expression can be regulated by specific stresses. Hypoxia and mechanical stretch, two likely stressors acting on the liver cyst epithelia, significantly increased IL-8 secretion and promoter activity. AP-1, c/EBP, and NF-kappaB were required but not sufficient to drive the stress-induced increase in IL-8 transcription. An upstream element between -272 and -1,481 bp allowed for the stress-induced increase in IL-8 transcription. These studies support the hypothesis that CXCR2 signaling promotes ADPKD liver cyst growth.

Clinical utilization of chemokines to combat cancer: the double-edged sword

Chemokines are a small group of related chemo-attractant peptides that play an essential role in the homeostatic maintenance of the immune system. They control the recruitment of cells needed for the induction and activation of innate and adaptive immune responses. However, tumors also utilize chemokines to actively progress and evade immunosurveillance. In fact, chemokines are involved directly or indirectly in almost every aspect of tumorigenesis. They mediate survival and metastatic spread of tumors, promote new blood vessel formation (neovascularization) and induce an immunosuppressive microenvironment via recruitment of immunosuppressive cells. As a result, a number of therapeutic strategies have been proposed to target almost every step of the chemokine/chemokine receptor involvement in tumors. Yet, despite occasional success stories, most of them appear to be ineffective or impractical, presumably due to 'nonspecific' harm of cells needed for the elimination of tumor escapees and maintenance of immunological memory. The strategy would only be effective if it also promoted antitumor adaptive immune responses capable of combating a residual disease and tumor relapse.

Effects of IFN-gamma and Stat1 on gene expression, growth, and survival in non-small cell lung cancer cells

Stat transcription factors are activated by cytokines and can activate pathways important in oncogenesis. Although previous studies have identified an oncogenic role of Stat3 in lung cancer cells, the role of Stat1 is unclear. Using a mutant of Stat1 with constitutive activity (Stat1C), we examined the effect of persistent Stat1 activity on lung cancer cell growth, survival and gene expression. We identified no significant effect of Stat1C alone or with interferon-gamma (IFN-gamma) on lung cancer cell growth or survival. Consistent with prior reports, Stat1C expression alone elicited minimal changes in gene expression and required costimulatory IFN-gamma for full activity. Using oligonucleotide gene arrays and quantitative real-time PCR, we identified numerous proinflammatory gene products and chemokines regulated by IFN-gamma/Stat1C signaling. These results suggest the major role of IFN-gamma and Stat1 in lung cells is to direct a proinflammatory gene expression program rather than have major effects on cell growth or survival or both.

G-protein-coupled receptors and cancer

G-protein-coupled receptors (GPCRs), the largest family of cell-surface molecules involved in signal transmission, have recently emerged as crucial players in tumour growth and metastasis. Malignant cells often hijack the normal physiological functions of GPCRs to survive, proliferate autonomously, evade the immune system, increase their blood supply, invade their surrounding tissues and disseminate to other organs. This Review will address our current understanding of the many roles of GPCRs and their signalling circuitry in tumour progression and metastasis. We will also discuss how interfering with GPCRs might provide unique opportunities for cancer prevention and treatment.