The chemokine receptor CCR4 promotes tumor growth and lung metastasis in breast cancer

Clinical significance of serum thymus and activation-regulated chemokine in gastric cancer: potential as a serum biomarker

Thymus and activation-regulated chemokine (TARC) can stimulate cancer cell proliferation and migration. The present study evaluated the clinical significance of serum TARC in gastric cancer (GC). We measured serum TARC, macrophage-derived chemokine, monocyte chemotactic protein-1 and stem cell factor (SCF) levels using a chemiluminescent immunoassay along the GC carcinogenesis (normal, high-risk, early GC [EGC] and advanced GC [AGC]) in both training (N = 25 per group) and independent validation datasets (90 normal, 30 high-risk, 50 EGC and 50 AGC). Serum levels were compared among groups using one-way analysis of variance. To evaluate the diagnostic potential of serum TARC for GC, receiver operating characteristic curve and logistic regression analyses were performed. Correlations between serum TARC and GC clinicopathological features were analyzed using Spearman's correlation. In the training dataset, serum TARC correlated with serum MDC, MCP-1 and SCF. However, only serum TARC and SCF were significantly higher in cancer groups than non-cancer groups (P < 0.001). In the validation dataset, serum TARC also increased along the GC carcinogenesis; the AGC group (167.2 ± 111.1 ng/mL) had significantly higher levels than the EGC (109.1 ± 67.7 ng/mL), the high-risk (66.2 ± 47.7 ng/mL) and the normal (67.5 ± 36.2 ng/mL) groups (Bonferroni, all P < 0.001). Receiver operating characteristic curves and logistic regression demonstrated the remarkable diagnostic potential of serum TARC as a single marker (72.0% sensitivity and 71.1% specificity; cutoff point, 0.37; logistic regression) and in a multiple-marker panel (72.6% sensitivity and 88.2% specificity; cutoff point, 0.54). Spearman's correlation showed that serum TARC was closely correlated with tumor size (γ_s = 0.227, P = 0.028), T-stage (γ_s = 0.340, P = 0.001), N-stage (γ_s = 0.318, P = 0.002) and M-stage (γ_s = 0.346, P = 0.001). Serum TARC is a promising serum biomarker for GC.

The role of the CCL22-CCR4 axis in the metastasis of gastric cancer cells into omental milky spots

Background

The omentum is one of the initial sites for peritoneal metastasis because it possesses milky spots that provide a microenvironment for cancer cells to readily migrate and grow into micrometastases. This study investigated the role of the CCL22-CCR4 axis in gastric cancer cells selectively infiltrating into milky spots.

Methods

Gastric cancer MFC cells labelled with DiI were injected intraperitoneally into strain 615 mice. The mice were euthanised at specified intervals and the omentum was excised for immunohistochemistry. The effects of CCL22 on the proliferation and migration of MFCs were assessed by MTT and trans-well assays. RT-PCR and Western blot analysis detected CCR4 mRNA and protein expression levels in MFCs. Immunohistochemistry was used to analyse CCL22 and CCR4 expression in the milky spot micrometastases.

Results

Two weeks after intraperitoneal injection, the milky spot areas were completely occupied by proliferating gastric cancer cells and cell cluster-type micrometastases were observed. In contrast, cancer cells formed single cell-type micrometastases in the non-milky spot areas. MFCs expressed CCR4, which was localised on the cell surface and or in the cytoplasm. Different concentrations of CCL22 significantly increased the proliferation ability of MFCs. Additionally, concentrations of CCL22 between 10–100 ng/ml significantly increased the migration of MFCs. Within omental milky spots, CCL22 was localised mainly on the cell surface and or in the cytoplasm. Within sections of omental milky spot micrometastases, CCR4 was recognised on or in gastric cancer cells, constituent cells milky spots, blood cells and blood endothelial cells.

Conclusions

Omental milky spots are a congenial microenvironment for peritoneal free gastric cancer cells to migrate, survive, and establish cell cluster-type metastases. The CCL22-CCR4 axis contributes to this selective infiltration process.

The role of chemoattractant receptors in shaping the tumor microenvironment

Chemoattractant receptors are a family of seven transmembrane G protein coupled receptors (GPCRs) initially found to mediate the chemotaxis and activation of immune cells. During the past decades, the functions of these GPCRs have been discovered to not only regulate leukocyte trafficking and promote immune responses, but also play important roles in homeostasis, development, angiogenesis, and tumor progression. Accumulating evidence indicates that chemoattractant GPCRs and their ligands promote the progression of malignant tumors based on their capacity to orchestrate the infiltration of the tumor microenvironment by immune cells, endothelial cells, fibroblasts, and mesenchymal cells. This facilitates the interaction of tumor cells with host cells, tumor cells with tumor cells, and host cells with host cells to provide a basis for the expansion of established tumors and development of distant metastasis. In addition, many malignant tumors of the nonhematopoietic origin express multiple chemoattractant GPCRs that increase the invasiveness and metastasis of tumor cells. Therefore, GPCRs and their ligands constitute targets for the development of novel antitumor therapeutics.

Inhibition of autophagy enhances the cytotoxic effect of PA-MSHA in breast cancer

Background

PA-MSHA, a genetically engineered Pseudomonas aeruginosa (PA) strain, is currently under investigation as a new anti-cancer drug. It can induce cell cycle arrest and apoptosis in different human cancer cells, including hormone receptor negative breast cancer cells. However, the underlying mechanism of tumor lethality mediated by PA-MSHA remains to be fully investigated.

Methods

The effect of PA-MSHA on human hormone receptor negative breast cancer cells was analyzed by morphological measurement, western blot, cell proliferation assay and mouse xenograft model.

Results

PA-MSHA was found to induce endoplasmic reticulum (ER) stress in breast cancer cell lines through the IRE1 signaling pathway. Inhibiting autophagy potentiated the cytotoxic effect of PA-MSHA while treating breast cancer cell lines. In mouse xenograft model, PA-MSHA produced more pronounced tumor suppression in mice inoculated with IRE1 gene knockdown. MDA-MB-231HM cells.

Conclusions

These findings demonstrated inhibiting autophagy together with PA-MSHA might be a promising therapeutic strategy in treating hormone receptor negative breast cancer cells.

Effects of sulforaphane and 3,3'-diindolylmethane on genome-wide promoter methylation in normal prostate epithelial cells and prostate cancer cells

Epigenetic changes, including aberrant DNA methylation, result in altered gene expression and play an important role in carcinogenesis. Phytochemicals such as sulforaphane (SFN) and 3,3'-diindolylmethane (DIM) are promising chemopreventive agents for the treatment of prostate cancer. Both have been shown to induce re-expression of genes, including tumor suppressor genes silenced in cancer cells, via modulation of epigenetic marks including DNA methylation. However, it remained unclear the effects SFN and DIM on DNA methylation at a genomic scale. The goal of this study was to determine the genome-wide effects of SFN and DIM on promoter methylation in normal prostate epithelial cells and prostate cancer cells. Both SFN and DIM treatment decreased DNA methyltransferase expression in normal prostate epithelial cells (PrEC), and androgen-dependent (LnCAP) and androgen-independent (PC3) prostate cancer cells. The effects of SFN and DIM on promoter methylation profiles in normal PrEC, LnCAP and PC3 prostate cancer cells were determined using methyl-DNA immunoprecipitation followed by genome-wide DNA methylation array. We showed widespread changes in promoter methylation patterns, including both increased and decreased methylation, in all three prostate cell lines in response to SFN or DIM treatments. In particular, SFN and DIM altered promoter methylation in distinct sets of genes in PrEC, LnCAP, and PC3 cells, but shared similar gene targets within a single cell line. We further showed that SFN and DIM reversed many of the cancer-associated methylation alterations, including aberrantly methylated genes that are dysregulated or are highly involved in cancer progression. Overall, our data suggested that both SFN and DIM are epigenetic modulators that have broad and complex effects on DNA methylation profiles in both normal and cancerous prostate epithelial cells. Results from our study may provide new insights into the epigenetic mechanisms by which SFN and DIM exert their cancer chemopreventive effects.

CCL17 Induces Trophoblast Migration and Invasion by Regulating Matrix Metalloproteinase and Integrin Expression in Human First-Trimester Placenta

Chemokines and chemokine receptors have been implicated a pivotal role in trophoblast differentiation and in the formation of a functionally normal placenta. In this study, we present data that highlight the involvement of chemokine ligand 17/chemokine receptor 4 (CCL17/CCR4) expression at the fetomaternal interface and expand its biological relevance of influence during trophoblast differentiation and placentation. By immunohistochemistry, we found that CCL17 was abundantly expressed in the decidua and trophoblasts, especially in cell columns. The receptor for CCL17, CCR4, was specifically expressed in invading interstitial extravillous trophoblasts. Furthermore, by transwell migration, invasion assays, and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, we found that exogenous CCL17 concentrations paralleled the invasive potential of cytotrophoblasts to some extent, with no significant effect on cell proliferation. Using Western blotting, we demonstrated that the stimulatory effect of CCL17 was related to the expression of matrix metalloproteinase 2 (MMP-2), MMP-13, integrin α5, and integrin β1, although it downregulated tissue inhibitors of MMP-1 expression. In conclusion, our findings suggest that CCL17, as a differentiation-related molecule coexpressed by decidua and trophoblast, stimulates extravillous trophoblast migration and directs invasion mainly via modulating integrins, MMPs, and its inhibitor levels.

CCR4 mediates CCL17 (TARC)-induced migration of human colon cancer cells via RhoA/Rho-kinase signaling

BACKGROUND

Accumulating data suggest a role of chemokines in tumor cell metastasis. CCR4 has been implicated in hematologic malignancies and recently also in solid tumors. Herein, we hypothesized that CCR4 might be expressed and support migration of colon cancer cells.

METHODS

We used quantitative RT-PCR and flow cytometry to determine mRNA and surface expression of CCR4 on colon cancer cell lines (HT-29) and (AZ-97). Total RhoA and active RhoA protein levels in CCL17-stimulated colon cancer cells were quantified using ELISA and G-LISA assays. Migration assays were performed to evaluate colon cancer cells chemotaxis. In vitro tumor growth was assessed using proliferation assay.

RESULTS

Our results show clear-cut mRNA levels and surface expression of CCR4 on a colon cancer cell line (HT-29) and on tumor cells (AZ-97). CCR4 ligand CCL17 (TARC) was a potent stimulator of colon cancer cell migration. This CCL17-induced colon cancer cell migration was inhibited by pre-incubation of the colon cancer cells with an antibody directed against CCR4 or an antagonist against CCR4. CCL17-induced signaling in colon cancer cells revealed that CCL17 increased mRNA formation of RhoA-C in colon cancer cells. Our results also found that CCL17 increased total RhoA and active RhoA protein levels in colon cancer cells. The Rho-kinase inhibitor Y-27632 abolished CCL17-induced colon cancer cell chemotaxis. In addition, inhibition of isoprenylation by GGTI-2133 markedly reduced colon cancer cell migration triggered by CCL17.

CONCLUSIONS

Our novel data indicate for the first time that the CCL17-CCR4 axis might be involved in the spread of colon cancer cells.

TLR4 is a novel determinant of the response to paclitaxel in breast cancer

Overexpression of Toll-like receptor-4 (TLR4) in human tumors often correlates with chemoresistance and metastasis. We found that TLR4 is overexpressed in the majority of clinical breast cancer samples and in 68% of the examined breast cancer lines. TLR4 is activated by lipopolysaccharide (LPS) and other ligands including the widely used drug paclitaxel. LPS is frequently used to show a tumor-promoting role of TLR4 although this bacterial component is unlikely to be found in the breast cancer environment. We reasoned that paclitaxel-dependent activation of TLR4 is more relevant to breast cancer chemoresistance that could be mediated by activation of the NF-κB pathway leading to upregulation of prosurvival genes. To test this hypothesis, we correlated TLR4 expression with resistance to paclitaxel in two modified breast cancer lines with either depleted or overexpressed TLR4 protein. Depletion of TLR4 in naturally overexpressing MDA-MB-231 cells downregulated prosurvival genes concomitant with 2- to 3-fold reduced IC(50) to paclitaxel in vitro and a 6-fold decrease in recurrence rate in vivo. Conversely, TLR4 overexpression in a negative cell line HCC1806 significantly increased expression of inflammatory and prosurvival genes along with a 3-fold increase of IC(50) to paclitaxel in vitro and enhanced tumor resistance to paclitaxel therapy in vivo. Importantly, both tumor models showed that many paclitaxel-upregulated inflammatory cytokines were coinduced with their receptors suggesting that this therapy induces autocrine tumor-promoting loops. Collectively, these results show that paclitaxel not only kills tumor cells but also enhances their survival by activating TLR4 pathway. These findings suggest that blocking TLR4 could significantly improve response to paclitaxel therapy.

Emerging targeted agents in metastatic breast cancer

Extensive preclinical experimentation has conceptually changed the way we perceive breast cancer, with the wide spectrum of genomic alterations governing its malignant progression now being recognized. Functional genomics has helped us identify important genetic defects that can be pharmaceutically targeted in the setting of metastatic disease. Rationally chosen combination regimens are now under clinical investigation. Recent data underline the functional importance of the tumour-associated stroma, with several candidate molecular targets now emerging. Data elucidating a cellular hierarchy within the breast cancer cellular compartment support the existence of a therapy-resistant subpopulation of breast cancer stem cells. Identification of the developmental pathways that dictate their malignant phenotype and use of high-throughput screening techniques are leading to new therapeutic avenues. In this Review, we present the biological rationale for the clinical development of more than 15 different classes of targeted agents in breast cancer, along with evidence supporting rational combinations. However, metastatic breast cancer resembles a Darwinian evolutionary system, with 'driver' mutations and epigenetic changes determining clonal selection according to branching trajectories. This evolution is reflected in the molecular heterogeneity of the disease and poses severe impediments to the successful clinical development of emerging targeted agents.

Cell surface receptor FPR2 promotes antitumor host defense by limiting M2 polarization of macrophages

FPR2 (Fpr2 in mouse) is a G-protein-coupled receptor interacting with bacterial and host-derived chemotactic agonists. Fpr2 supports innate and adaptive immune responses as illustrated by the reduction in severity of allergic airway inflammation in Fpr2-KO mice, due to impaired trafficking of antigen-presenting dendritic cells (DC). The aim of this study is to examine the role of Fpr2 in host antitumor responses. We found that Fpr2-KO mice bearing subcutaneously implanted Lewis lung carcinoma (LLC) cells exhibited significantly shortened survival than normal mice due to more rapidly growing tumors. In contrast, in Fpr2-transgenic mice overexpressing Fpr2, subcutaneously implanted LLC tumors grew more slowly than those in wild-type (WT) littermates. Investigation of tumor tissues revealed an increased number of macrophages associated with tumors grown in Fpr2-KO mice. Macrophages derived from Fpr2-KO mice showed a more potent chemotactic response to LLC-derived supernatant (LLC Sup), which could be neutralized by an anti-CCL2 antibody. The increased chemotaxis of Fpr2-KO mouse macrophages in response to LLC Sup was due to their higher level expression of CCR4, a chemokine receptor that also recognizes the ligand CCL2. Furthermore, macrophages from Fpr2-KO mice acquired an M2 phenotype after stimulation with LLC Sup. These results suggest that Fpr2 plays an important role in host defense against implanted LLC by sustaining macrophages in an M1 phenotype with more potent antitumor activities.

Autocrine and paracrine loops between cancer cells and macrophages promote lymph node metastasis via CCR4/CCL22 in head and neck squamous cell carcinoma

Lymph node metastasis is a poor prognostic factor for patients with head and neck squamous cell carcinoma (HNSCC). However, its molecular mechanism has not yet been fully understood. In our study, we investigated the expression of CCR4 and its ligand CCL22 in the HNSCC tumor microenvironment and found that the CCR4/CCL22 axis was involved in lymph node metastasis of HNSCC. CCR4 was expressed in 20 of 31 (64.5%) human tongue cancer tissues, and its expression was significantly correlated with lymph node metastasis (p < 0.01) and lymphatic invasion (p < 0.05). CCR4 was expressed in three of five human HNSCC cell lines tested. CCR4(+) HNSCC cells, but not CCR4(-) cells, showed enhanced migration toward CCL22, indicating that functional CCR4 was expressed in HNSCC cell lines. CCL22 was also expressed in cancer cells (48.4% of tongue cancer tissues) or CD206(+) M2-like macrophages infiltrated in tumors and draining lymph nodes. CCL22 produced by cancer cells or CD206(high) M2-like macrophages increased the cell motility of CCR4(+) HNSCC cells in vitro in an autocrine or paracrine manner. In the mouse SCCVII in vivo model, CCR4(+) cancer cells, but not CCR4(-) cells, metastasized to lymph nodes which contained CCL22 producing M2-like macrophages. These results demonstrate that lymph node metastasis of CCR4(+) HNSCC is promoted by CCL22 in an autocrine or M2-like macrophage-dependent paracrine manner. Therefore, the CCR4/CCL22 axis may be an attractive target for the development of diagnostic and therapeutic strategies for patients with HNSCC.

Expression of CXCL14 and its anticancer role in breast cancer

CXCL14, also known as breast and kidney-expressed chemokine, was initially identified as a chemokine highly expressed in the kidney and breast. The exact function of CXCL14 in human breast cancer is still unclear, although it has been testified to play an anti-tumor role in other tumors, including head and neck squamous cell carcinoma, lung cancer, prostate cancer, and so on. In this study, we tried to demonstrate the relationship between CXCL14 and breast cancer. CXCL14 expressions were detected by reverse transcription-PCR and western blot in 2 normal breast epithelial cell lines and 6 breast cancer cell lines. The effects of CXCL14 on the proliferation and invasion in vitro were tested using the CXCL14-overexpressing cells (MDA-MB-231HM-CXCL14) which were established by stable transfection. We established an orthotropic xenograft tumor model in SCID mice using the MDA-MB-231HM-CXCL14 cells and explored the influence of CXCL14 overexpression on tumor growth and metastasis in vivo. Furthermore, we detected the protein level of CXCL14 in 208 breast cancer patients by immunohistochemistry and discussed the correlation between CXCL14 and the prognosis of breast cancer. CXCL14 mRNA expression is lower in breast cancer cell lines, and MDA-MB-231HM express the lowest levels of CXCL14 mRNA. Overexpression of CXCL14 inhibited cell proliferation and invasion in vitro and attenuated xenograft tumor growth and lung metastasis in vivo. CXCL14 protein level is positively correlated to the overall survival of all patients as well as the patients with lymph node metastasis, and it has a negative correlation with the lymph node metastasis. Our study showed for the first time that CXCL14 is a negative regulator of growth and metastasis in breast cancer. The re-expression or up-regulation of this gene may provide a novel strategy in breast cancer therapy in the future.

Differential Expression of Chemokine Receptors and their Roles in Cancer Imaging

Chemokine/chemokine receptor interactions play diverse roles in cell migration and homeostasis. Emerging evidence suggests that cancer cells co-opt chemokine networks for survival, proliferation, immune evasion, and metastasis. Most of the chemokine receptors are reported to be involved in tumor progression. Given their extensive implication in cancer progression, several chemokine receptor/ligand axes are considered as potential therapeutic targets. This review provides a survey of chemokine receptor expression in cancer and evaluates the potential of chemokine receptor imaging as a tool for molecular characterization of cancer.

Bioengineering embryonic stem cell microenvironments for the study of breast cancer

Breast cancer is the most prevalent disease amongst women worldwide and metastasis is the main cause of death due to breast cancer. Metastatic breast cancer cells and embryonic stem (ES) cells display similar characteristics. However, unlike metastatic breast cancer cells, ES cells are nonmalignant. Furthermore, embryonic microenvironments have the potential to convert metastatic breast cancer cells into a less invasive phenotype. The creation of in vitro embryonic microenvironments will enable better understanding of ES cell-breast cancer cell interactions, help elucidate tumorigenesis, and lead to the restriction of breast cancer metastasis. In this article, we will present the characteristics of breast cancer cells and ES cells as well as their microenvironments, importance of embryonic microenvironments in inhibiting tumorigenesis, convergence of tumorigenic and embryonic signaling pathways, and state of the art in bioengineering embryonic microenvironments for breast cancer research. Additionally, the potential application of bioengineered embryonic microenvironments for the prevention and treatment of invasive breast cancer will be discussed.