Macrophage inflammatory protein-2 promotes angiogenesis, cell migration, and tumor growth in hepatic metastasis

Contemporaneous Inflammatory, Angiogenic, Fibrogenic, and Angiostatic Cytokine Profiles of the Time-to-Tumor Development by Cancer Cells to Orchestrate Tumor Neovascularization, Progression, and Metastasis

Cytokines can promote various cancer processes, such as angiogenesis, epithelial to mesenchymal transition (EMT), invasion, and tumor progression, and maintain cancer stem-cell-like (CSCs) cells. The mechanism(s) that continuously promote(s) tumors to progress in the TME still need(s) to be investigated. The data in the present study analyzed the inflammatory, angiogenic, fibrogenic, and angiostatic cytokine profiles in the host serum during tumor development in a mouse model of human pancreatic cancer. Pancreatic MiaPaCa-2-eGFP cancer cells were subcutaneously implanted in RAG2xCγ double mutant mice. Blood samples were collected before cancer cell implantation and every week until the end point of the study. The extracted serum from the blood of each mouse at different time points during tumor development was analyzed using a Bio-Plex microarray analysis and a Bio-Plex 200 system for proinflammatory (IL-1β, IL-10, IFN-γ, and TNF-α) and angiogenic and fibrogenic (IL-15, IL-18, basic FGF, LIF, M-CSF, MIG, MIP-2, PDGF-BB, and VEGF) cytokines. Here, we find that during cancer cell colonization for tumor development, host angiogenic, fibrogenic, and proinflammatory cytokine profiling in the tumor-bearing mice has been shown to significantly reduce host angiostatic and proinflammatory cytokines that restrain tumor development and increase those for tumor growth. The proinflammatory cytokines IL-15, IL-18, and IL-1β profiles reveal a significant host serum increase after day 35 when the tumor began to progress in growth. In contrast, the angiostatic cytokine profiles of TNFα, MIG, M-CSF, IL-10, and IFNγ in the host serum revealed a dramatic and significant decrease after day 5 post-implantation of cancer cells. OP treatment of tumor-bearing mice on day 35 maintained high levels of angiostatic and fibrogenic cytokines. The data suggest an entirely new regulation by cancer cells for tumor development. The findings identify for the first time how pancreatic cancer cells use host cytokine profiling to orchestrate the initiation of tumor development.

MicroRNA‑27a‑3p regulates the proliferation and chemotaxis of pulmonary macrophages in non‑small cell lung carcinoma tissues through CXCL2

The present study aimed to investigate microRNA (miRNA)-27a-3p expression in the pulmonary macrophages and peripheral blood of patients with early non-small cell lung carcinoma (NSCLC) and its regulatory effect on the infiltration of pulmonary macrophages into cancer tissues and invasion of NSCLC cells. Blood specimens were withdrawn from 36 patients with NSCLC and 29 healthy subjects. NSCLC tissues and cancer-adjacent tissues were both obtained from patients with NSCLC; furthermore, certain tissue samples were used to extract macrophages. The levels of miRNA-27a-3p and C-X-C motif ligand chemokine 2 (CXCL2) mRNA were detected by reverse transcription-quantitative PCR and the levels of CXCL2 protein were measured by ELISA and western blot analysis. A dual-luciferase reporter assay was performed to determine the interactions between miRNA and mRNA. An MTT assay was employed to examine the viability of transfected cells and macrophages and a Transwell assay was performed to assess chemotaxis. The differential expression of miRNA-27a-3p in NSCLC tissues, pulmonary macrophages and peripheral blood indicated that miRNA-27a-3p exerted different roles in these specimens. CXCL2 was upregulated in NSCLC tissues at both transcriptional and translational levels. In addition, the untranslated region of CXCL2 was confirmed to be directly targeted by miRNA-27a-3p prior to its transcriptional activation. Furthermore, miRNA-27a-3p regulated CXCL2 expression, thereby affecting the proliferation of human pulmonary macrophages. The present study highlights that miRNA-27a-3p expression in the pulmonary macrophages and peripheral blood of patients with NSCLC is downregulated, while its target gene CXCL2 is upregulated. miRNA-27a-3p may regulate the viability and chemotaxis of macrophages in tumor tissues of patients with NSCLC through CXCL2 and is expected to become a genetic marker of this disease.

The Role of Inflammatory Mediators in Colorectal Cancer Hepatic Metastasis

Colorectal cancer (CRC) is the second leading cause of death in cancer patients in the USA, whereas the major cause of CRC deaths is hepatic metastases. The liver is the most common site of metastasis in patients with CRC due to hepatic portal veins receiving blood from the digestive tract. Understanding the cellular and molecular mechanisms of hepatic metastases is of dire need for the development of potent targeted therapeutics. Immuno-signaling molecules including cytokines and chemokines play a pivotal role in hepatic metastases from CRC. This brief review discusses the involvement of three representative cytokines (TNF-α, IL-6 and IL-1β), a lipid molecule PGE2 and two chemokines (CXCL1 and CXCL2) in the process of CRC liver metastases.

CXCL2-CXCR2 axis mediates αV integrin-dependent peritoneal metastasis of colon cancer cells

Peritoneal metastasis is an insidious aspect of colorectal cancer. The aim of the present study was to define mechanisms regulating colon cancer cell adhesion and spread to peritoneal wounds after abdominal surgery. Mice was laparotomized and injected intraperitoneally with CT-26 colon carcinoma cells and metastatic noduli in the peritoneal cavity was quantified after treatment with a CXCR2 antagonist or integrin-αV-antibody. CT-26 cells expressed cell surface chemokine receptors CXCR2, CXCR3, CXCR4 and CXCR5. Stimulation with the CXCR2 ligand, CXCL2, dose-dependently increased proliferation and migration of CT-26 cells in vitro. The CXCR2 antagonist, SB225002, dose-dependently decreased CXCL2-induced proliferation and migration of colon cancer cells in vitro. Intraperitoneal administration of CT-26 colon cancer cells resulted in wide-spread growth of metastatic nodules at the peritoneal surface of laparotomized animals. Laparotomy increased gene expression of CXCL2 at the incisional line. Pretreatment with CXCR2 antagonist reduced metastatic nodules by 70%. Moreover, stimulation with CXCL2 increased CT-26 cell adhesion to extracellular matrix (ECM) proteins in a CXCR2-dependent manner. CT-26 cells expressed the αV, β1 and β3 integrin subunits and immunoneutralization of αV abolished CXCL2-triggered adhesion of CT-26 to vitronectin, fibronectin and fibrinogen. Finally, inhibition of the αV integrin significantly attenuated the number of carcinomatosis nodules by 69% in laparotomized mice. These results were validated by use of the human colon cancer cell line HT-29 in vitro. Our data show that colon cancer cell adhesion and growth on peritoneal wound sites is mediated by a CXCL2-CXCR2 signaling axis and αV integrin-dependent adhesion to ECM proteins.

Characteristics of CXCL2 expression in coronary atherosclerosis and negative regulation by microRNA-421

Objective

The study investigated expression of microRNA (miR)-421 in plaques, peripheral blood mononuclear cells (PBMCs), and serum from patients with coronary atherosclerosis.

Methods

Thirty-three patients with coronary atherosclerosis and 29 healthy individuals were included. Plaque tissue and adjacent intimal tissue were collected from patients. Peripheral blood was collected from patients and healthy individuals. Quantitative real-time PCR was used to determine expression of C-X-C motif chemokine ligand 2 (CXCL2) mRNA and miR-421. Western blotting was used to measure expression of CXCL2 protein in plaques and PBMCs, and ELISA was used to detect serum levels of CXCL2. A dual luciferase reporter assay was carried out to test whether CXCL2 mRNA directly interacts with miR-421.

Results

Patients with coronary atherosclerosis had elevated expression of CXCL2 mRNA and protein in plaques, PBMCs, and serum compared with healthy controls but reduced expression of miR-421. The dual luciferase reporter assay showed that miR-421 could bind with the 3′-untranslated seed region of CXCL2 mRNA to regulate its expression.

Conclusion

We demonstrated that elevated expression of CXCL2 in plaques, PBMCs, and serum of patients with coronary atherosclerosis was related to downregulation of miR-421 expression. miR-421 plays a role in the occurrence of coronary atherosclerosis, probably through CXCL2.

Omental adipocytes promote peritoneal metastasis of gastric cancer through the CXCL2-VEGFA axis

Background

Gastric cancer (GC) patients frequently develop peritoneal metastasis; however, the underlying mechanism remains unknown. We hypothesised that omental adipocytes (OmAd) trigger GC cells towards malignant activity to induce peritoneal metastasis.

Methods

We analysed interactions among human GC cells, endothelial cells and OmAd using a 3D co-culture system. We also employed a multipronged animal study, including subcutaneous and orthotopic tumours, and humanised omental adipose tissue models. Urinary levels of CXCL2 were analysed in human GC patients with and without peritoneal metastasis.

Results

Conditioned media derived from OmAd (OmAd-CM) promoted the proliferation, migration and capacity to induce angiogenesis of GC cells through AKT phosphorylation and VEGFA overexpression, whereas silencing CXCL2 in OmAd cancelled OmAd-induced effects. In an orthotopic tumour model using SCID mice, omentectomy suppressed GC growth and peritoneal dissemination, and reduced serum levels of CXCL2. OmAd promoted GC growth in a humanised omental adipose tissue model using NSG mice, but silencing CXCL2 in OmAd cancelled OmAd-induced tumour growth. Finally, urinary levels of CXCL2 were significantly higher in GC patients with peritoneal metastasis than in those without.

Conclusion

Omental adipocytes trigger GC cells to an aggressive phenotype through CXCL2 secretion, which induces angiogenesis followed by cell growth and peritoneal metastasis.

Overexpression of CXCL2 inhibits cell proliferation and promotes apoptosis in hepatocellular carcinoma

C-X-C motif chemokine ligand 2 (CXCL2) is a small secreted protein that exhibits a structure similar to the proangiogenic subgroup of the CXC chemokine family. Recently, accumulating evidence suggests that chemokines play a pivotal role in cancer progression and carcinogenesis. We examined the expression levels of 7 types of ELR＋ CXCLs messenger RNA (mRNA) in 264 clinical samples. We found that CXCL2 expression was stably down-regulated in 94% of hepatocellular carcinoma (HCC) specimens compared with paired adjacent normal liver tissues and some HCC cell lines. Moreover, CXCL2 overexpression profoundly attenuated HCC cell proliferation and growth and induced apoptosis in vitro. In animal studies, we found that overexpressing CXCL2 by lentivirus also apparently inhibited the size and weight of subcutaneous tumours in nude mice. Furthermore, we demonstrated that CXCL2 induced HCC cell apoptosis via both nuclear and mitochondrial apoptosis pathways. Our results indicate that CXCL2 negatively regulates the cell cycle in HCC cells via the ERK1/2 signalling pathway. These results provide new insights into HCC and may ultimately lead to the discovery of innovative therapeutic approaches of HCC. [BMB Reports 2018; 51(12): 630-635].

Neutrophil extracellular traps promote peritoneal metastasis of colon cancer cells

Cytoreductive surgery is the only curative option for patients with peritoneal carcinomatosis, however, intraperitoneal recurrence rate is high making new ways to prevent cancer recurrence an urgent need. Recent evidence suggests that neutrophils are involved in cancer progression. The purpose of our study was to examine the role of neutrophils in the spread of colon cancer cells in the peritoneal cavity.

The number of metastatic noduli in the peritoneal cavity was quantified in mice injected with murine colon cancer cells (CT-26) intraperitoneally after surgical laparotomy and treated with a neutrophil depleting antibody or DNase I. In addition, peritoneal metastases were harvested from patients with peritoneal carcinomatosis. Scanning and transmission electron microscopy showed extensive neutrophil extracellular trap (NET) formation in peritoneal colon cancer metastases in mice and patients. Neutrophil depletion markedly reduced the number of metastases in laparotomised animals. Administration of DNase I decreased the number of metastatic nodules by 88% in laparotomised animals as well as NET-induced chemokine-dependent colon cancer cell migration and adhesion in vitro. Finally, CT-26 cancer cells were found to express the α_vβ₃ integrin and inhibition of αv integrin abolished NET-induced adhesion of colon cancer cells to vitronectin. Taken together, our data show that NETs play an important role in colon cancer cell metastasis in the peritoneal cavity and regulate colon cancer cell migration and adhesion to extracellular matrix proteins. These novel findings suggest that targeting NETs might be an effective strategy to antagonize intrabdominal recurrences of colon cancer after cytoreductive surgery in patients with peritoneal carcinomatosis.

Induction of interleukin-1β by mouse mammary tumor irradiation promotes triple negative breast cancer cells invasion and metastasis development

PURPOSE

Radiotherapy increases the level of inflammatory cytokines, some of which are known to promote metastasis. In a mouse model of triple negative breast cancer (TNBC), we determined whether irradiation of the mammary tumor increases the level of key cytokines and favors the development of lung metastases.

MATERIALS AND METHODS

D2A1 TNBC cells were implanted in the mammary glands of a Balb/c mouse and then 7 days old tumors were irradiated (4 × 6 Gy). The cytokines IL-1β, IL-4, IL-6, IL-10, IL-17 and MIP-2 were quantified in plasma before, midway and after irradiation. The effect of tumor irradiation on the invasion of cancer cells, the number of circulating tumor cells (CTC) and lung metastases were also measured.

RESULTS

TNBC tumor irradiation significantly increased the plasma level of IL-1β, which was associated with a greater number of CTC (3.5-fold) and lung metastases (2.3-fold), compared to sham-irradiated animals. Enhancement of D2A1 cell invasion in mammary gland was associated with an increase of the matrix metalloproteinases-2 and -9 activity (MMP-2, -9). The ability of IL-1β to stimulate the invasiveness of irradiated D2A1 cells was confirmed by in vitro invasion chamber assays.

CONCLUSION

Irradiation targeting a D2A1 tumor and its microenvironment increased the level of the inflammatory cytokine IL-1β and was associated with the promotion of cancer cell invasion and lung metastasis development.

Type conversion of secretomes in a 3D TAM2 and HCC cell co-culture system and functional importance of CXCL2 in HCC

Macrophages play important roles in the tumor microenvironment, driving cancer progression and metastasis, particularly in hepatocellular carcinoma (HCC). However, few studies have assessed the exact secretome composition in HCC. In the present study, the impact of different phenotype of macrophages on HCC cells was investigated. Alternatively activated macrophages (M2) were found to significantly increase the proliferation, migration, and invasion abilities of SMMC7721 cells (all P < 0.05). M2 were then co-cultured with SMMC7721 cells to reconstruct the tumor microenvironment. Conditioned medium from 3D single cultures of M2, SMMC7721 cells, and their co-culture system were analyzed using quantitative proteomics via iTRAQ labeling combined with mass spectrometric analysis. Secretome analysis revealed a total of 159 differential secreted proteins in the co-culture system compared to the single culture systems, with 63 being up-regulated (>1.3-fold) and 96 down-regulated (<0.7-fold). CXCL2 was confirmed to have higher expression in the co-culture system and HCC tissues, and was selected for further investigation. Functional effects data suggested that recombinant human CXCL2 significantly enhanced the migration, invasion ability of SMMC7721 cells, and weakened adhesion ability. While CXCL2 neutralization and CXCR2 blockage significantly inhibited the effects of CXCL2 on SMMC7721 cells, indicating that CXCL2 may play pivotal role in HCC metastasis.

Clinical significance of serum interleukin-29, interleukin-32, and tumor necrosis factor alpha levels in patients with gastric cancer

Many studies suggested that cytokines interleukin (IL)-29, IL-32, and tumor necrosis factor alpha (TNF-α) are implicated in the pathogenesis of malignancies. The purpose of this study was to determine the clinical significance of the serum levels of IL-29, IL-32, and TNF-α in gastric cancer (GC) patients. Fifty-eight GC patients and 20 age- and sex-matched healthy controls were enrolled into this study. The median age at diagnosis was 59.5 years (range 32-82 years). Tumor localization of the majority of the patients was antrum (n = 42, 72.4 %), and tumor histopathology of the majority of the patients was diffuse (n = 43, 74.1 %). The majority of the patients had stage IV disease (n = 41, 70.7 %). Thirty-six (62.1 %) patients had lymph node involvement. The median follow-up time was 66 months (range 1 to 97.2 months). The baseline serum IL-29 concentrations were not different between patients and controls (p = 0.627). The baseline serum IL-32 and TNF-α concentrations of the GC patients were significantly higher (for IL-32, p = 0.014; for TNF-α, p = 0.001). Gender, localization, histopathology, tumor, and lymph node involvement were not found to be correlated with serum IL-29, IL-32, and TNF-α concentrations (p > 0.05). Patients without metastasis (p = 0.01) and patients who responded to chemotherapy (p = 0.04) had higher serum IL-29 concentrations. Patients older than 60 years had higher serum IL-32 (p = 0.002). Serum IL-29, IL-32, and TNF-α levels were not associated with outcome (p = 0.30, p = 0.51, and p = 0.41, respectively). In conclusion, serum levels of IL-32 and TNF-α may be diagnostic markers, and serum IL-29 levels may be associated with good prognosis in patients with GC.

Significant association between IL-32 gene polymorphisms and susceptibility to endometrial cancer in Chinese Han women

Interleukin-32 (IL-32), a pro-inflammatory chemokine, has been reported to be involved in inflammatory, infectious diseases and even cancers. This study aimed to investigate whether two genetic variants (rs28372698 and rs12934561) of IL-32 were associated with susceptibility to endometrial cancer (EC) in Chinese Han women by a hospital-based study with 272 EC patients and 337 healthy controls. Our results showed that the frequencies of TT genotype (P = 0.012, OR = 2.37, 95 % CI = 1.32-4.28) and T allele (P = 0.026, OR = 1.320, 95 % CI = 1.036-1.681) of rs28372698 in EC patients were significantly higher than controls. Clinical analyses indicated the TT genotype frequency was relevant to high clinical stage and cervical invasion. Furthermore, the frequencies of CC genotype (P = 0.0077, OR = 1.62, 95 % CI = 1.05-2.50) and C allele (P = 0.043, OR = 1.269, 95 % CI = 1.011-1.592) of rs12934561 were also significantly higher in EC patients than controls. Stratification analyses revealed that CC genotype was more frequent in endometrioid adenocarcinoma or EC without parametrial invasion. This study demonstrates that IL-32 gene polymorphisms are significantly associated with increased EC susceptibility in Chinese Han women.

Chemokines in chronic liver allograft dysfunction pathogenesis and potential therapeutic targets

Despite advances in immunosuppressive drugs, long-term success of liver transplantation is still limited by the development of chronic liver allograft dysfunction. Although the exact pathogenesis of chronic liver allograft dysfunction remains to be established, there is strong evidence that chemokines are involved in organ damage induced by inflammatory and immune responses after liver surgery. Chemokines are a group of low-molecular-weight molecules whose function includes angiogenesis, haematopoiesis, mitogenesis, organ fibrogenesis, tumour growth and metastasis, and participating in the development of the immune system and in inflammatory and immune responses. The purpose of this review is to collect all the research that has been done so far concerning chemokines and the pathogenesis of chronic liver allograft dysfunction and helpfully, to pave the way for designing therapeutic strategies and pharmaceutical agents to ameliorate chronic allograft dysfunction after liver transplantation.

Mouse β-defensin 14 (Defb14) promotes tumor growth by inducing angiogenesis in a CCR6-dependent manner

β-Defensins are known for their antimicrobial activity and belong to the molecular barrier of the innate immune system against invading pathogens. In addition, it has been shown that some members of the β-defensin superfamily have the capacity to promote local innate inflammatory and systemic adaptive immune responses, mediated in part by the interaction with CCR6. We found that mouse β-defensin 14 (mBD14, Defb14), a newly identified member of the mouse β-defensin superfamily, is expressed in mouse fibrosarcoma tumor tissue. Tumor cells overexpressing mBD14 demonstrated enhanced solid tumor growth in syngeneic C57BL/6 mice concomitant with increased vascularization of these tumors. Furthermore, mBD14-overexpressing tumors demonstrated increased expression of proangiogenic MIP-2 (CXCL2) ex vivo. In contrast, vascular endothelial growth factor expression was not affected. Cellular analysis of tumor-infiltrating leukocytes revealed a significant increase of CCR6(+) B220(+) lymphocytes in solid tumors derived from mBD14-overexpressing tumor cells. Enhanced tumor growth of mBD14-overexpressing fibrosarcomas was abolished in CCR6-deficient mice, which was paralleled by decreased infiltration of CCR6(+) B220(+) lymphocytes, indicating the requirement of CCR6 expression on host cells. Previously, the interaction of activated, LTαβ(+), lymphocytes with lymphotoxin β-receptor-expressing fibrosarcoma tumor cells has been identified as a new CXCL2-dependent proangiogenic pathway. Coexpression of a soluble lymphotoxin β-receptor:Ig fusion protein, an inhibitor of CXCL2-dependent angiogenesis, in mBD14-overexpressing fibrosarcoma tumor cells abolished enhanced solid tumor growth. Thus, we conclude that mBD14 expression by tumor-infiltrating host cells results in the chemoattraction of CCR6(+) B220(+) lymphocytes, which in turn initiates a proangiogenic pathway leading to enhanced angiogenesis and organized tumor tissue development.

A functional role for Nlrp6 in intestinal inflammation and tumorigenesis

The nucleotide-binding oligomerization domain-like receptor (NLR) family member, Nlrp6, has been implicated in inflammasome signaling to activate caspase-1, which is essential for the production of mature IL-1β and IL-18. However, a function for Nlrp6 in vivo has never been demonstrated. Due to the relative high expression of Nlrp6 in intestinal tissue, we hypothesized that Nlrp6 has a role in intestinal homeostasis. Indeed, Nlrp6-deficient mice are more susceptible to chemically induced colitis as well as colitis-induced tumorigenesis than wild-type (WT) mice. Nlrp6-deficient mice exhibited significantly more inflammation within the colon than WT mice after dextran sulfate sodium treatment. Their inability to resolve inflammation and repair damaged epithelium as efficiently as WT mice resulted in prolonged increases in epithelial proliferative activity that likely underlie the increased propensity for tumors in these mice during chronic inflammation. We further show that the activity of Nlrp6 in hematopoietic cells is critical for protection against inflammation-related colon tumorigenesis. This study highlights the importance of NLR function in maintaining intestinal homeostasis to prevent the development of aberrant inflammation and tumor development within the colon.

Association of intra-tumoral infiltrating macrophages and regulatory T cells is an independent prognostic factor in gastric cancer after radical resection

BACKGROUND

Macrophages (Mφ) and regulatory T cells (Tregs) are the major components of the inflammatory infiltrate in virtually all tumors. The objective of this study was to investigate the prognostic significance of Mφ and Tregs infiltration in advanced gastric cancer after radical resection.

METHODS

CD68(+) Mφ and FOXP3(+) Tregs were assessed by immunohistochemistry in tissues from 107 patients with surgically advanced gastric cancer. The microlocalization of Mφ and Tregs cells with respect to the development of gastric cancer were given special concern. Prognostic value of normal, peritumoral, and intratumoral Mφ and Tregs densities was evaluated by Kaplan-Meier analysis and Cox regression.

RESULTS

The results showed that the presence of intratumoral CD68(+) Mφ was an independent prognostic factor for overall survival (OS) (P = 0.02). Moreover, the combination of high numbers of intratumoral CD68(+) Mφ and FOXP3(+) Tregs was associated with improved survival (P = 0.041). Five-year OS rate was only 27% for patients with low intratumoral Mφ and intratumoral Tregs compared with 62% for patients with high intratumoral Mφ and intratumoral Tregs. In addition, advanced intestinal-type gastric cancers were more likely to have fewer infiltrating Mφ than diffuse-type cancers (P = 0.024).

CONCLUSIONS

Association of intratumoral Mφ and Tregs is a promising independent predictor for survival in advanced gastric cancer. The results suggested that a combination of concomitant stimulation of intratumoral Mφ and Tregs may be an effective strategy for treatment of patients with advanced gastric cancer after radical resection.

Altered phenotype of lymphatic endothelial cells induced by highly metastatic OTSCC cells contributed to the lymphatic metastasis of OTSCC cells

The lymphatic endothelial cell (LEC) is an interactive surface for cancer cells. This article aims to explore cancer cell-induced changes of LEC, and study the tumor-lymphatic endothelium interaction. Here, LECs were co-cultured with highly and poorly metastatic tongue cancer cells. The differences in biologic behaviors and gene expression profiles between them were examined. The results showed that LECs induced by highly metastatic cancer cells displayed abnormal biologic behaviors, and could secrete chemokines to promote the migration of cancer cells. Therefore, biologic properties and functional status of LECs in oral tongue squamous cell carcinoma (OTSCC) might be a positive factor in lymphatic dissemination.

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.

The role of chemokines in intestinal inflammation and cancer

Chronic inflammation is a risk factor for several gastrointestinal malignancies, including colorectal cancer. Recent epidemiological studies and clinical trials demonstrate that long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) markedly reduced the relative risk of colorectal cancer. Chronic inflammation associated with development of cancer is partly driven by the chemokine system. Chemokines are chemoattractant cytokines that recruit leukocytes from the circulatory system to local inflammatory sites. In this review, we highlight recent breakthroughs in our understanding of the role of chemokines in inflammatory bowel disease and colorectal cancer from animal models and human studies. These findings provide a rationale for the development of new anti-inflammatory therapeutic approaches for prevention and/or treatment of inflammatory bowel disease and colorectal cancer.

Differential CXC receptor expression in colorectal carcinomas

In this study, we aimed to assess the expression profile of chemokine receptors CXCR1-4 in inflammatory and malignant colorectal diseases and corresponding hepatic metastases of synchronous and metachronous origin to elucidate their role in colorectal cancer (CRC) progression and metastasis. Chemokine receptor expression was assessed by quantitative real-time PCR, immunohistochemistry (IHC) and Western blot analysis in resection specimens from patients with ulcerative colitis (UC, n = 25), colorectal adenomas (CRA, n = 8), different stages of CRC (n = 48) as well as colorectal liver metastases (CRLM) along with their corresponding primary colorectal tumours (n = 16). While none of the chemokine receptors were significantly upregulated or downregulated in UC or CRA tissues, CXC receptors 1, 2 and 4 demonstrated a significant increase in expression in all tumour stages of CRC specimens with CXCR4 correlating with tumour grading (P < 0.05). On the other hand, CXCR3 showed no significant upregulation in either tumour stage, but significant overexpression in CRLM. While CXCR4 demonstrated significant upregulation in both tumour entities, IHC analysis revealed that the predominate cell type expressing CXCR4 in CRC is represented by tumour cells, whereas in CRLM the majority of positive CXCR4 signals is due to hepatocytes along the tumour invasion front. In conclusion, our findings show a very differential expression pattern of the four receptors in colorectal carcinomas and their corresponding liver metastases with prominent expression profiles that indicate a potential role in the pathogenesis of CRC.

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.

Correlation of IL-8 with induction, progression and metastatic potential of colorectal cancer

AIM: To investigate the expression profile of IL-8 in inflammatory and malignant colorectal diseases to evaluate its potential role in the regulation of colorectal cancer (CRC) and the development of colorectal liver metastases (CRLM).

METHODS: IL-8 expression was assessed by quantitative real-time PCR (Q-RT-PCR) and the enzyme-linked immunosorbent assay (ELISA) in resected specimens from patients with ulcerative colitis (UC, n = 6) colorectal adenomas (CRA, n = 8), different stages of colorectal cancer (n = 48) as well as synchronous and metachronous CRLM along with their corresponding primary colorectal tumors (n = 16).

RESULTS: IL-8 mRNA and protein expression was significantly up-regulated in all pathological colorectal entities investigated compared with the corresponding neighboring tissues. However, in the CRC specimens IL-8 revealed a significantly more pronounced overexpression in relation to the CRA and UC tissues with an average 30-fold IL-8 protein up-regulation in the CRC specimens in comparison to the CRA tissues. Moreover, IL-8 expression revealed a close correlation with tumor grading. Most interestingly, IL-8 up-regulation was most enhanced in synchronous and metachronous CRLM, if compared with the corresponding primary CRC tissues. Herein, an up to 80-fold IL-8 overexpression in individual metachronous metastases compared to normal tumor neighbor tissues was found.

CONCLUSION: Our results strongly suggest an association between IL-8 expression, induction and progression of colorectal carcinoma and the development of colorectal liver metastases.

Adhesion molecules and chemokines: the navigation system for circulating tumor (stem) cells to metastasize in an organ-specific manner

To date, cancer is still the second most prevalent cause of death after cardiovascular diseases in the industrialized word, whereby the primary cause of cancer is not attributed to primary tumor formation, but rather to the growth of metastases at distant organ sites. For several years it was considered that the well-known phenomenon of organ-specific spreading of tumor cells is mostly a mechanical process either directed passively due to size constraints (mechanical trapping theory) or due to a fertile environment provided by the organ in which tumor cells can proliferate (seed and soil hypothesis). Both mechanisms strongly depend on the adhesive properties of tumor cells either to endothelial cells and/or cancer cells, which are facilitated by a variety of cell adhesion molecules including carbohydrates and integrins. Within the past years it became evident that the organ-specific metastatic spreading of tumor cells does not only rely on heterotypic and homotypic adhesive interactions, but also on the interplay of chemokines and their appropriate receptors. Moreover, the identification of cancer stem cells in various tumor tissues has opened new questions. Cancer stem cells possess self-renewal, differentiation, and tumor-initiating capacities. Thus these cells are ideal candidates to be the seed of a secondary tumor. In the present review we will give a brief overview about the complex process of organ-specific metastasis formation depending on the interplay of adhesion molecules, chemokines, and the putative role of cancer stem cells in metastasis formation.

Liver resection-associated macrophage inflammatory protein-2 stimulates engraftment but not growth of colorectal metastasis at extrahepatic sites

BACKGROUND

Previous studies have shown that liver resection enhances intrahepatic engraftment of CXCR-2-expressing colorectal cancer cells by the action of the CXC chemokine macrophage inflammatory protein (MIP)-2. Herein we studied how liver resection-associated MIP-2 affects extrahepatic tumor cell engraftment and whether MIP-2 also stimulates the growth of already established metastases.

MATERIALS AND METHODS

Green fluorescent protein-transfected CT26.WT colorectal cancer cells were implanted into dorsal skinfold chambers of syngeneic BALB/c mice. Additionally, all animals underwent a 30% hepatectomy. To study MIP-2 in extrahepatic tumor cell engraftment, animals were treated with an anti-MIP-2 antibody, starting at the day of tumor cell implantation. To study MIP-2 in established metastases, anti-MIP-2 treatment was initiated at day 5 after tumor cell implantation. Hepatectomized animals without neutralization of MIP-2 served as controls. Tumor vascularization and growth as well as tumor cell migration, proliferation, apoptosis, and CXCR-2 expression were studied over 14 days using intravital fluorescence microscopy, histology, and immunohistochemistry.

RESULTS

Functional inhibition of MIP-2 significantly delayed extrahepatic tumor cell engraftment but not the growth of established metastases. The initial delay of engraftment was associated with a compensatory stimulation of vascularization and tumor cell migration when compared to controls (P < 0.05). Further, inhibition of tumor cell engraftment by initial anti-MIP-2 treatment was associated with a significant (P < 0.05) reduction of CXCR-2 expression and tumor cell apoptosis.

CONCLUSION

Our study indicates that MIP-2 is involved in extrahepatic engraftment of CT.26 colorectal cancer cells. The MIP-2/CXCR-2 signaling pathway may be a promising target for early antitumor therapy in patients undergoing liver resection.

Studies on MIP-2 and CXCR2 expression in a mouse model of extrahepatic colorectal metastasis

AIMS

The CXC chemokine macrophage inflammatory protein (MIP)-2 has been shown to promote outgrowth of colorectal liver metastasis by enhancing angiogenesis and tumor cell migration. However, the effect of MIP-2 on extrahepatic metastasis is not known yet. With a use of a murine model, we therefore studied cell proliferation and microvascularization of extrahepatic CT26.WT-GFP colorectal tumors after exposure to MIP-2.

METHODS

Green fluorescent protein (GFP)-transfected CT26.WT colorectal cancer cells were implanted in dorsal skinfold chambers of syngeneic BALB/c mice. After 5 days, the tumors were locally exposed to 100 nM MIP-2. Cell proliferation as well as tumor microvascularization and growth were studied during a further 9-day period using intravital fluorescence microscopy, histology and immunohistochemistry. Tumors exposed to PBS served as controls.

RESULTS

MIP-2 induced a marked CXCR2 expression and promoted a distinct tumor cell proliferation. This was associated with a significant increase of tumor size compared to PBS-treated controls. Of interest, MIP-2 did not affect dilation and permeability of the tumor microvessels, which would be indicators for an enhanced VEGF action. Accordingly, the angiogenic response, e.g. the outgrowth of new microvessels, was not affected, and the density of the established tumor microvascular network was even found decreased after MIP-2 exposure when compared to PBS controls.

CONCLUSION

With the use of a murine tumor model, we demonstrate that MIP-2 accelerates growth of experimentally established extrahepatic colorectal metastases by inducing tumor cell proliferation rather than promoting vascularization.

Major but not minor hepatectomy accelerates engraftment of extrahepatic tumor cells

BACKGROUND

The effect of hepatectomy and hepatic regeneration on intra- and extrahepatic tumor growth is still controversially discussed. Herein we studied the effect of minor (30%) or major (70%) hepatectomy on engraftment of extrahepatic tumor cells, and the role of tumor neovascularization and tumor cell migration.

METHODS

Green fluorescent protein (GFP)-transfected CT26.WT colorectal cancer cells were implanted in dorsal skinfold chambers of syngeneic BALB/c mice. Animals underwent 30% (30%Phx, n = 8) or 70% hepatectomy (70%Phx, n = 8). Sham-operated animals served as controls (n = 8). Angiogenesis and neovascularization as well as tumor cell migration, proliferation and growth were studied over 14 days using intravital fluorescence microscopy, histology and immunohistochemistry.

RESULTS

After both minor and major hepatectomy tumor proliferating cell nuclear antigen (PCNA) expression increased significantly (P < 0.05) when compared with nonhepatectomized controls. However, only major but not minor hepatectomy accelerated neovascularization (P < 0.05) and tumor cell migration (P < 0.05). This was associated with a significantly (P < 0.05) enhanced tumor growth after 70%Phx when compared with 30%Phx and controls. The rate of apoptotic cell death was not affected by major or minor hepatectomy.

CONCLUSION

Regeneration after major hepatectomy accelerates extrahepatic tumor cell engraftment, most probably by acceleration of neovascularization and induction of tumor cell migration.

Role of chemokine receptor CXCR4/CXCL12 signaling pathway in hepatic metastasis of colorectal carcinoma

AIM: To investigate the potential role of chemokine receptor CXCR4/CXCL12 signal transduction pathway in hepatic metastasis of colorectal carcinoma.

METHODS: CXCR4 and CXCL12 expression were detected in tissue samples from 60 patients with colorectal carcinoma representing various clinicopathological parameters by Western blot analysis.

RESULTS: The levels of CXCR4 and CXCL12 proteins expression were increased significantly in colorectal cancer as compared with those in the adjacent normal mucosa (P < 0.05). In the 10 patients with lymph node metastasis, the expression of CXCR4 and CXCL12 were also markedly higher than those in those without metastasis (CXCR4: 3.9 ± 0.5 vs 2.2 ± 0.3, P < 0.05; CXCL12: 3.6 ± 0.5 vs 2.4 ± 0.3, P < 0.05). The over-expression of CXCR4 and CXCL12 proteins were correlated with TNM staging, and they were highly elevated in colorectal cancer at Ⅲ and Ⅳ stages as compared with those at Ⅰ and Ⅱ stages (CXCR4: 3.4 ± 0.6 vs 1.8 ± 0.3, P < 0.05; CXCL12: 3.6 ± 0.5 vs 1.8 ± 0.4, P < 0.05).

CONCLUSION: Over-expression of CXCR4/CXCL12 plays an important role in the hepatic metastasis of colorectal carcinoma.