Tumor-derived CCL5 does not contribute to breast cancer progression

Lactobacillus intestinalis facilitates tumor-derived CCL5 to recruit dendritic cell and suppress colorectal tumorigenesis

Gut microbes play a crucial role in regulating the tumor microenvironment (TME) of colorectal cancer (CRC). Nevertheless, the deep mechanism between the microbiota-TME interaction has not been well explored. In this study, we for the first time discovered that Lactobacillus intestinalis (L. intestinalis) effectively suppressed tumor growth both in the AOM/DSS-induced CRC model and the ApcMin/+ spontaneous adenoma model. Our investigation revealed that L. intestinalis increased the infiltration of immune cells, particularly dendritic cells (DC), in the TME. Mechanically, the tumor-derived CCL5 induced by L. intestinalis recruited DC chemotaxis through the NOD1/NF-κB signaling pathway. In clinical samples and datasets, we found positive correlation between L. intestinalis, CCL5 level, and the DC-related genes. Our study provided a new strategy for microbial intervention for CRC and deepened the understanding of the interaction between tumor cells and the immune microenvironment modulated by gut microbes.

CCL5 Deficiency Enhanced Cryo–Thermal-Triggered Long-Term Anti-Tumor Immunity in 4T1 Murine Breast Cancer

Breast cancer remains one of the most common solid tumors. Tumor immunosuppressive factors mainly hinder the control of tumors. We previously developed an innovative cryo–thermal therapy that was shown to significantly suppress distal metastasis and improve long-term survival in murine B16F10 melanoma and 4T1 mammary carcinoma models. However, the effect of cryo–thermal therapy on the 4T1 model was not excellent. CCL5 has been reported to help the progression of breast cancer, so in this study, CCL5−/− was used to explore the role of host-derived CCL5 after cryo–thermal therapy. CCL5−/− could not completely resist tumor development, but it significantly improved survival rates when combined with cryo–thermal therapy. Mechanically, CCL5−/− mildly decreases the percentage of MDSCs, increases DC maturation and macrophage’s inflammatory function at an early stage after tumor inoculation, and later up-regulate the level of Th1 and down-regulate the level of Tregs. When combined with cryo–thermal therapy, CCL5−/− dramatically down-regulated the proportion of MDSCs and induced full M1 macrophage polarization, which further promoted Th1 differentiation and the cytotoxicity of CD8+ T cells. Our results indicated that CCL5−/− contributed to cryo–thermal-triggered, long-lasting anti-tumor memory immunity. The combination of cryo–thermal therapy and CCL5 blockades might extend the survival rates of patients with aggressive breast cancer.

Potential Molecular Cross Talk Among CCR5 Pathway Predicts Regorafenib Responsiveness in Metastatic Colorectal Cancer Patients

BACKGROUND

Genetic variants in the CCL5/CCR5 pathway have been shown to predict regorafenib efficacy in patients with metastatic colorectal cancer (mCRC). This study investigated the biological role of CCL4 and CCL3 gene polymorphisms in patients with refractory mCRC treated using regorafenib.

PATIENTS AND METHODS

We analyzed the genomic DNA extracted from mCRC patients receiving regorafenib. Serum factor levels at baseline, day 21, and progressive disease (PD) were measured using ELISA.

RESULTS

Decreased CCL4 levels at day 21 or increased CCL3 levels at PD were associated with better clinical outcomes. In patients with any CCL5 rs2280789 G allele, CCL3 significantly increased between BL and day 21 compared with the A/A variant (72.7% vs. 23.1%, p=0.006), but CCL4 decreased (31.8% vs. 69.2%, p=0.043).

CONCLUSION

Increased CCL3 and decreased CCL4 seen in specific genotypes may serve as potential biomarkers of regorafenib in mCRC patients.

CCL5-armed oncolytic virus augments CCR5-engineered NK cell infiltration and antitumor efficiency

BACKGROUND

Natural killer (NK) cells have potent antitumor activities. Nevertheless, adoptive transfer therapy of NK cells has gained very limited success in patients with solid tumors as most infused NK cells remain circulating in the peripheral blood instead of entering tumor sites. Chemokines and their receptors play important roles in NK cell distribution. Enhancing chemokine receptors on immune cells to match and be driven to tumor-specific chemokines may improve the therapeutic efficacy of NK cells.

METHODS

The CCR5-CCL5 axis is critical in NK cell homing to tumor sites. Thus, we analyzed CCR5 expression on NK cells from patients with cancer and healthy donors. We then upregulated CCR5 and CCL5 with lentiviruses and oncolytic viruses in NK and tumor cells, respectively. Animal experiments were also carried out to test the efficacy of the combination of oncolytic virus with NK cells.

RESULTS

In NK cells from patients with various solid tumors or healthy subjects, CCR5 was expressed at low levels before and after expansion in vitro. CCR5-engineered NK cells showed enhanced tumor infiltration and antitumor effects, but no complete regressions were noted in the in vivo tumor models. To further improve therapeutic efficacy, we constructed CCL5-expressing oncolytic vaccinia virus. In vitro data demonstrated that vaccinia virus can produce CCL5 in tumor cells while infectivity remained unaffected. Supernatants from tumor cells infected by CCL5-modified vaccinia virus enhanced the directional movement of CCR5-overexpressed NK cells but not green fluorescent protein (GFP)-expressing cells. More importantly, NK cells were resistant to the vaccinia virus and their functions were not affected after being in contact. In vivo assays demonstrated that CCL5-expressing vaccinia virus induced a greater accumulation of NK cells within tumor lesions compared with that of the prototype virus.

CONCLUSION

Enhancement of matched chemokines and chemokine receptors is a promising method of increasing NK cell homing and therapeutic effects. Oncolytic vaccinia viruses that express specific chemokines can synergistically augment the efficacies of NK cell-based therapy.

Significant association between high serum CCL5 levels and better disease-free survival of patients with early breast cancer

Analysis of anticancer immunity aids in assessing the prognosis of patients with breast cancer. From 250 operated breast cancers, we focused on serum levels of C‐C motif chemokine ligand 5 (CCL5), which is involved in cancer immune reactions. Serum levels of CCL5 were measured using a cytometric bead‐based immunoassay kit and CCL5 expression in cancer cells was determined using immunohistochemical staining. In addition, mRNA in cancer and stromal cells was analyzed by microdissection and comparison with the public dataset. Disease‐free survival (DFS) of patients with high CCL5 levels (cut‐off, 13.87 ng/mL; n = 192) was significantly better than those with low CCL5 levels (n = 58; hazard ratio, 0.20; 95% confidence interval, 0.10‐0.39; P < .0001). An improved overall survival was observed in patients with high CCL5 levels compared to those with low CCL5 levels (P = .024). On the contrary, high immunohistochemical expression of CCL5 in cancer cells was significantly associated with decreased DFS. As serum CCL5 levels did not correlate with CCL5 expression in cancer cells and the relative expression of mRNA CCL5 was elevated in stromal cells in relation to cancer cells, serum CCL5 might be derived not from cancer cells, but from stromal cells. Expression of CCL5 in serum, but not in cancer cells, might contribute to improved patient prognosis mediating through not only immune reaction, but through other mechanisms. Determination of circulating CCL5 levels could be useful for predicting patient prognosis.

Genetic Variation in CCL5 Signaling Genes and Triple Negative Breast Cancer: Susceptibility and Prognosis Implications

Triple-negative breast cancer (TNBC) accounts for ~15–20% of breast cancer (BC) and has a higher rate of early relapse and mortality compared to other subtypes. The Chemokine (C-C motif) ligand 5 (CCL5) and its signaling pathway have been linked to TNBC. We aimed to investigate the susceptibility and prognostic implications of genetic variation in CCL5 signaling genes in TNBC in the present study. We characterized variants in CCL5 and that of six other CCL5 signaling genes (CCND1, ZMIZ1, CASP8, NOTCH2, MAP3K21, and HS6ST3) among 1,082 unrelated Tunisian subjects (544 BC patients, including 196 TNBC, and 538 healthy controls), assessed the association of the variants with BC-specific overall survival (OVS) and progression-free survival (PFS), and correlated CCL5 mRNA and serum levels with CCL5 genotypes. We found a highly significant association between the CCND1 rs614367-TT genotype (OR = 5.14; P = 0.004) and TNBC risk, and identified a significant association between the rs614367-T allele and decreased PFS in TNBC. A decreased risk of lymph node metastasis was associated with the MAP3K21 rs1294255-C allele, particularly in rs1294255-GC (OR = 0.47; P = 0.001). CCL5 variants (rs2107538 and rs2280789) were linked to CCL5 serum and mRNA levels. In the TCGA TNBC/Basal-like cohort the MAP3K21 rs1294255-G allele was associated with a decreased OVS. High expression of CCL5 in breast tumors was significantly associated with an increased OVS in all BC patients, but particularly in TNBC/Basal-like patients. In conclusion, genetic variation in CCL5 signaling genes may predict not only TNBC risk but also disease aggressiveness.

Adipose microenvironment promotes triple negative breast cancer cell invasiveness and dissemination by producing CCL5

Growing evidence indicates that adiposity is associated with raised cancer incidence, morbidity and mortality. In a subset of tumors, cancer cell growth and/or metastasis predominantly occur in adipocyte-rich microenvironment. Indeed, adipocytes represent the most abundant cell types surrounding breast cancer cells. We have studied the mechanisms by which peritumoral human adipose tissue contributes to Triple Negative Breast Cancer (TNBC) cell invasiveness and dissemination.

Co-culture with human adipocytes enhanced MDA-MB231 cancer cell invasiveness. Adipocytes cultured in high glucose were 2-fold more active in promoting cell invasion and motility compared to those cultured in low glucose. This effect is induced, at least in part, by the CC-chemokine ligand 5 (CCL5). Indeed, CCL5 inhibition by specific peptides and antibodies reduced adipocyte-induced breast cancer cell migration and invasion. CCL5 immuno-detection in peritumoral adipose tissue of women with TNBC correlated with lymph node (p-value = 0.04) and distant metastases (p-value = 0.001). A positive trend was also observed between CCL5 expression and glycaemia. Finally, Kaplan-Meier curves showed a negative correlation between CCL5 staining in the peritumoral adipose tissue and overall survival of patients (p-value = 0.039).

Thus, inhibition of CCL5 in adipose microenvironment may represent a novel approach for the therapy of highly malignant TNBC.

Cytokine profiling of tumor interstitial fluid of the breast and its relationship with lymphocyte infiltration and clinicopathological characteristics

The tumor microenvironment is composed of many immune cell subpopulations and is an important factor in the malignant progression of neoplasms, particularly breast cancer (BC). However, the cytokine networks that coordinate various regulatory events within the BC interstitium remain largely uncharacterized. Moreover, the data obtained regarding the origin of cytokine secretions, the levels of secretion associated with tumor development, and the possible clinical relevance of cytokines remain controversial. Therefore, we profiled 27 cytokines in 78 breast tumor interstitial fluid (TIF) samples, 43 normal interstitial fluid (NIF) samples, and 25 matched serum samples obtained from BC patients with Luminex xMAP multiplex technology. Eleven cytokines exhibited significantly higher levels in the TIF samples compared with the NIF samples: interleukin (IL)-7, IL-10, fibroblast growth factor-2, IL-13, interferon (IFN)γ-inducible protein (IP-10), IL-1 receptor antagonist (IL-1RA), platelet-derived growth factor (PDGF)-β, IL-1β, chemokine ligand 5 (RANTES), vascular endothelial growth factor, and IL-12. An immunohistochemical analysis further demonstrated that IL-1RA, IP-10, IL-10, PDGF-β, RANTES, and VEGF are widely expressed by both cancer cells and tumor-infiltrating lymphocytes (TILs), whereas IP-10 and RANTES were preferentially abundant in triple-negative breast cancers (TNBCs) compared to Luminal A subtype cancers. The latter observation corresponds with the high level of TILs in the TNBC samples. IL-1β, IL-7, IL-10, and PDGFβ also exhibited a correlation between the TIF samples and matched sera. In a survival analysis, high levels of IL-5, a hallmark T_H2 cytokine, in the TIF samples were associated with a worse prognosis. These findings have important implications for BC immunotherapy research.

Text mining, a race against time? An attempt to quantify possible variations in text corpora of medical publications throughout the years

BACKGROUND

The continuous growth of medical sciences literature indicates the need for automated text analysis. Scientific writing which is neither unitary, transcending social situation nor defined by a timeless idea is subject to constant change as it develops in response to evolving knowledge, aims at different goals, and embodies different assumptions about nature and communication. The objective of this study was to evaluate whether publication dates should be considered when performing text mining.

METHODS

A search of PUBMED for combined references to chemokine identifiers and particular cancer related terms was conducted to detect changes over the past 36 years. Text analyses were performed using freeware available from the World Wide Web. TOEFL Scores of territories hosting institutional affiliations as well as various readability indices were investigated. Further assessment was conducted using Principal Component Analysis. Laboratory examination was performed to evaluate the quality of attempts to extract content from the examined linguistic features.

RESULTS

The PUBMED search yielded a total of 14,420 abstracts (3,190,219 words). The range of findings in laboratory experimentation were coherent with the variability of the results described in the analyzed body of literature. Increased concurrence of chemokine identifiers together with cancer related terms was found at the abstract and sentence level, whereas complexity of sentences remained fairly stable.

CONCLUSIONS

The findings of the present study indicate that concurrent references to chemokines and cancer increased over time whereas text complexity remained stable.

Esophageal Squamous Cell Carcinoma Cells Modulate Chemokine Expression and Hyaluronan Synthesis in Fibroblasts

The aim of this study was to characterize the interaction of KYSE-410, an esophageal squamous cell carcinoma cell line, and fibroblasts with respect to the extracellular matrix component hyaluronan (HA) and chemokine expression. KYSE-410 cells induced the mRNA expression of HA synthase 2 (Has2) in normal skin fibroblasts (SF) only in direct co-cultures. Parallel to Has2 mRNA, Has2 antisense RNA (Has2os2) was up-regulated in co-cultures. Knockdown of LEF1, a downstream target of Wnt signaling, abrogated Has2 and Has2os2 induction. After knockdown of Has2 in SF, significantly less α-smooth muscle actin expression was detected in co-cultures. Moreover, it was investigated whether the phenotype of KYSE-410 was affected in co-culture with SF and whether Has2 knockdown in SF had an impact on KYSE-410 cells in co-culture. However, no effects on epithelial-mesenchymal transition markers, proliferation, and migration were detected. In addition to Has2 mRNA, the chemokine CCL5 was up-regulated and CCL11 was down-regulated in SF in co-culture. Furthermore, co-cultures of KYSE-410 cells and cancer-associated fibroblasts (CAF) were investigated. Similar to SF, Has2 and Ccl5 were up-regulated and Ccl11 was down-regulated in CAF in co-culture. Importantly and in contrast to SF, inhibiting HA synthesis by 4-methylumbelliferone abrogated the effect of co-culture on Ccl5 in CAF. Moreover, HA was found to promote adhesion of CD4(+) but not CD8(+) cells to xenogaft tumor tissues. In conclusion, direct co-culture of esophageal squamous cell carcinoma and fibroblasts induced stromal HA synthesis via Wnt/LEF1 and altered the chemokine profile of stromal fibroblasts, which in turn may affect the tumor immune response.

The potential to target CCL5/CCR5 in breast cancer

INTRODUCTION

Chemokines play a crucial role in breast cancer tumorigenesis and progression. Recently, the chemokine (C-C motif) ligand 5 (CCL5), which can be secreted either by tumor cells or by mesenchymal stromal cells recruited to the tumor, has been identified as a key node in the bidirectional communication between breast cancer and normal cells.

AREAS COVERED

In this review, the authors discuss the role of CCL5/chemokine receptor 5 (CCR5) axis in promoting breast cancer onset and progression. Interrogation of large clinical databases has demonstrated increased expression of the CCL5/CCR5 axis in specific subtypes of breast cancer. The activation of the receptor CCR5 in breast cancer cells controls their invasiveness serving as a driver for metastasis. Furthermore, the CCL5/CCR5 axis participates in the recruitment of specific immune cells into tumors, inducing local immunosuppression and favoring tumor progression.

EXPERT OPINION

The role of CCR5 in HIV infection led to the development of specific and potent CCR5 antagonists. The data reviewed here includes basic and translational studies that support the use of such CCR5 antagonists in breast cancer patients as adjuvant therapy to block the metastasis.

CC chemokine receptor 5: the interface of host immunity and cancer

Solid tumors are embedded in a stromal microenvironment consisting of immune cells, such as macrophages and lymphocytes, as well as nonimmune cells, such as endothelial cells and fibroblasts. Chemokines are a type of small secreted chemotactic cytokine and together with their receptors play key roles in the immune defense. Critically, they regulate cancer cellular migration and also contribute to their proliferation and survival. The CCR5 chemokine receptor is involved in leucocytes chemotaxis to sites of inflammation and plays an important role in the macrophages, T cells, and monocytes recruitment. Additionally, CCR5 may have an indirect effect on cancer progression by controlling the antitumor immune response, since it has been demonstrated that its expression could promote tumor growth and contribute to tumor metastasis, in different types of malignant tumors. Furthermore, it was demonstrated that a CCR5 antagonist may inhibit tumor growth, consisting of a possible therapeutic target. In this context, the present review focuses on the establishment of CCR5 within the interface of host immunity, tumor microenvironment, and its potential as a targeting to immunotherapy.

CCL5 as a potential immunotherapeutic target in triple-negative breast cancer

Breast cancer (BC) is a leading cause of mortality among women in the world. To date, a number of molecules have been established as disease status indicators and therapeutic targets. The best known among them are estrogen receptor-α (ER-α), progesterone receptor (PR) and HER-2/neu. About 15%-20% BC patients do not respond effectively to therapies targeting these classes of tumor-promoting factors. Thus, additional targets are strongly and urgently sought after in therapy for human BCs negative for ER, PR and HER-2, the so-called triple-negative BC (TNBC). Recent clinical work has revealed that CC chemokine ligand 5 (CCL5) is strongly associated with the progression of BC, particularly TNBC. How CCL5 contributes to the development of TNBC is not well understood. Experimental animal studies have begun to address the mechanistic issue. In this article, we will review the clinical and laboratory work in this area that has led to our own hypothesis that targeting CCL5 in TNBCs will have favorable therapeutic outcomes with minimal adverse impact on the general physiology.

A novel role of hematopoietic CCL5 in promoting triple-negative mammary tumor progression by regulating generation of myeloid-derived suppressor cells

CCL5 is a member of the CC chemokine family expressed in a wide array of immune and non-immune cells in response to stress signals. CCL5 expression correlates with advanced human breast cancer. However, its functional significance and mode of action have not been established. Here, we show that CCL5-deficient mice are resistant to highly aggressive, triple-negative mammary tumor growth. Hematopoietic CCL5 is dominant in this phenotype. The absence of hematopoietic CCL5 causes aberrant generation of CD11b(+)/Gr-1(+), myeloid-derived suppressor cells (MDSCs) in the bone marrow in response to tumor growth by accumulating Ly6C(hi) and Ly6G(+) MDSCs with impaired capacity to suppress cytotoxicity of CD8(+) T cells. These properties of CCL5 are observed in both orthotopic and spontaneous mammary tumors. Antibody-mediated systemic blockade of CCL5 inhibits tumor progression and enhances the efficacy of therapeutic vaccination against non-immunogenic tumors. CCL5 also helps maintain the immunosuppressive capacity of human MDSCs. Our study uncovers a novel, chemokine-independent activity of the hematopoietically derived CCL5 that promotes mammary tumor progression via generating MDSCs in the bone marrow in cooperation with tumor-derived colony-stimulating factors. The study sheds considerable light on the interplay between the hematopoietic compartment and tumor niche. Because of the apparent dispensable nature of this molecule in normal physiology, CCL5 may represent an excellent therapeutic target in immunotherapy for breast cancer as well as a broad range of solid tumors that have significant amounts of MDSC infiltration.

CCR5 antagonist blocks metastasis of basal breast cancer cells

The roles of the chemokine CCL5 and its receptor CCR5 in breast cancer progression remain unclear. Here, we conducted microarray analysis on 2,254 human breast cancer specimens and found increased expression of CCL5 and its receptor CCR5, but not CCR3, in the basal and HER-2 genetic subtypes. The subpopulation of human breast cancer cell lines found to express CCR5 displayed a functional response to CCL5. In addition, oncogene transformation induced CCR5 expression, and the subpopulation of cells that expressed functional CCR5 also displayed increased invasiveness. The CCR5 antagonists maraviroc or vicriviroc, developed to block CCR5 HIV coreceptor function, reduced in vitro invasion of basal breast cancer cells without affecting cell proliferation or viability, and maraviroc decreased pulmonary metastasis in a preclinical mouse model of breast cancer. Taken together, our findings provide evidence for the key role of CCL5/CCR5 in the invasiveness of basal breast cancer cells and suggest that CCR5 antagonists may be used as an adjuvant therapy to reduce the risk of metastasis in patients with the basal breast cancer subtype.

Relationship between CCL5 and transforming growth factor-β1 (TGFβ1) in breast cancer

PURPOSE

Investigate circulating CCL5 in breast cancer patients and healthy controls, along with gene expression levels in corresponding tumour tissue and isolated primary stromal cells. Hormonal control of CCL5, and a potential relationship with TGFβ1, was also investigated.

METHODS

Circulating levels of CCL5 and TGFβ1 were measured in 102 breast cancer patients and 66 controls using ELISA. Gene expression levels (CCL5, CCR5, TGFβ1, TGFβRII) were quantified in corresponding tumour tissue (n = 43), normal tissue (n = 16), and isolated tumour (n = 22) and normal (n = 3) stromal cells using RQ-PCR. CCL5 and circulating menstrual hormones (LH, FSH, Oestradiol, Progesterone) were analysed in serum samples from healthy, premenopausal volunteers (n = 60).

RESULTS

TGFβ1 was significantly higher in breast cancer patients (Mean(SEM) 27.4(0.9)ng/ml) compared to controls (14.9(0.9)ng/ml). CCL5 levels decreased in the transition from node negative (59.6(3.7)ng/ml) to node positive disease (40.5(6.3)ng/ml) and increased again as the number of positive lymph nodes increased (⩾3 positive 50.95(9.8)ng/ml). A significant positive correlation between circulating CCL5 and TGFβ1 (r = 0.423, p<0.0001) was observed, and mirrored at the gene expression level in tumour tissue from the same patients (r = 0.44, p<0.001). CCL5, CCR5 and TGFβ1 expression was significantly higher in tumour compared to normal breast tissue (p < 0.001). A significant negative correlation was observed between circulating CCL5, Oestradiol and Progesterone (r = -0.50, r = -0.39, respectively, p < 0.05).

CONCLUSION

CCL5 expression is elevated in the tumour microenvironment. The data support a role for hormonal control of circulating CCL5 and also highlight a potentially important relationship between CCL5 and TGFβ1 in breast cancer.

Expression of the inflammatory chemokines CCL2, CCL5 and CXCL2 and the receptors CCR1-3 and CXCR2 in T lymphocytes from mammary tumor-bearing mice

Chemokines and their receptors have been studied in several solid tumor models as mediators of inflammation. In turn, inflammation has been implicated in the promotion and progression of tumors, and as such, chemokines have been proposed as novel molecular targets for chemotherapy. While the expression of these molecules has been described in tumor cells, endothelial cells, macrophages and neutrophils, less attention has been paid to the expression profile of these molecules by T lymphocytes in the periphery or infiltrating the tumor. Using the D1-DMBA-3 murine mammary adenocarcinoma model, we aimed to better characterize the differential expression of chemokines and/or their receptors in the host and in the tumor microenvironment, and specifically, in the T cells of tumor-bearing mice compared to normal control animals. We found that T lymphocytes from tumor-bearing mice express the pro-inflammatory chemokines, CCL2, CCL5 and CXCL2, as well as the chemokine receptors, CCR1, CCR2, CCR3 and CXCR2.

Tumor-secreted PGE2 inhibits CCL5 production in activated macrophages through cAMP/PKA signaling pathway

One of the major characteristics of tumors is their ability to evade immunosurveillance through altering the properties and functions of host stromal and/or immune cells. CCL5 has been shown to play important roles in T cell proliferation, IFN-γ, and IL-2 production, which promotes the differentiation and proliferation of Th1 cells important for immune defense against intracellular infection. In this study we found that tumor-bearing mice were more susceptible to bacterial infection and showed reduced CCL5 levels in serum during endotoxic shock. Our data further demonstrated that the soluble factors secreted by mammary gland tumor cells but not normal mammary gland epithelial cells inhibited CCL5 expression in macrophages in response to LPS, but not to TNF-α stimulation. The inhibitory effect of tumor-secreted molecules on LPS-induced CCL5 expression was regulated at the post-transcriptional level. Blocking PGE(2) synthesis by NS398 or through the use of PGE(2) receptor antagonists AH-6809 (EP2 antagonist) and AH-23848 (EP4 antagonist) completely reversed the inhibitory effect of tumor-conditioned medium (TCM) on LPS-induced CCL5 expression. Moreover, PGE(2) and the cAMP analog forskolin could mimic tumor-mediated CCL5 inhibition, and the inhibitory effects of TCM, PGE(2), and cAMP analog on LPS-induced CCL5 expression could be completely reversed by the PKA inhibitor H89. Furthermore, blocking PGE(2) synthesis in vivo led to partial recovery of CCL5 production during endotoxic shock. Taken together, our data indicate that PGE(2) secreted from breast cancer cells suppresses CCL5 secretion in LPS-activated macrophages through a cAMP/PKA signaling pathway, which may result in suppression of host immune responses against subsequent bacterial infection.

CCL5 as an adjuvant for cancer immunotherapy

IMPORTANCE OF THE FIELD

To date cancer immunotherapy has only achieved limited clinical efficacy, thus more efficient immunotherapeutic approaches need to be explored. The CC chemokine CCL5 plays a role in chemoattraction and activation of immune cells implying its potential clinical application as an adjuvant for boosting anti-tumor immunity, although an effect on carcinogenesis and tumor cell invasiveness is also reported to be associated with CCL5.

AREAS COVERED IN THIS REVIEW

Recent progress in exploiting CCL5 as an adjuvant for cancer prevention and treatment, and updated understanding on how CCL5 is involved in tumor invasiveness and carcinogenesis.

WHAT THE READER WILL GAIN

CCL5 represents a natural adjuvant for enhancing anti-tumor immune responses. However, animal experiments and clinical reports suggest that CCL5 plays a role in carcinogenesis and invasiveness of tumor cells. Therefore, a CCL5-based cancer therapeutic approach needs to avoid the CCL5-associated potential detrimental effects.

TAKE HOME MESSAGE

CCL5 has a pre-eminent role in chemotaxis and activation of a wide spectrum of immune cells. CCL5 functions as an adjuvant to boost anti-tumor immunity by diverse protocols such as co-immunization of recombinant CCL5 protein with tumor-associated antigen, vaccination with CCL-5-expressing tumor cells, or viral vector delivery of CCL5 cDNA into growing tumor. CCL5 may also promote tumor cell survival, proliferation and invasion by different mechanisms.

Concomitant expression of the chemokines RANTES and MCP-1 in human breast cancer: a basis for tumor-promoting interactions

The chemokines RANTES (CCL5) and MCP-1 (CCL2) were suggested to contribute, independently, to breast malignancy. In the present study, we asked if the two chemokines are jointly expressed in clinical samples of breast cancer patients, and do they interact in breast tumor cells. We found that RANTES and MCP-1 were expressed by breast tumor cells in primary tumors of Ductal Carcinoma In Situ and of Invasive Ductal Carcinoma, but minimally in normal breast epithelial duct cells. The chemokines were also detected in metastases and pleural effusions. Novel findings showed that co-expression of RANTES and MCP-1 in the same tumor was associated with more advanced stages of disease, suggesting that breast tumors "benefit" from interactions between the two chemokines. Accordingly, MCP-1 significantly promoted the release of RANTES from endogenous pre-made vesicles, in an active process that depended on calcium from intracellular and extracellular sources, and on intracellular transport of RANTES towards exocytosis. Our findings show a chemokine-triggered release of stored pro-malignancy chemokine from breast tumor cells. These observations support a major tumor-promoting role for co-expression of the chemokines in breast malignancy, and agree with the significant association of joint RANTES and MCP-1 expression with advanced stages of breast cancer.