Blockade of the chemokine receptor, CCR5, reduces the growth of orthotopically injected colon cancer cells via limiting cancer-associated fibroblast accumulation

Tumor-associated mesenchymal stromal cells modulate macrophage phagocytosis in stromal-rich colorectal cancer via PD-1 signaling

CMS4 colorectal cancer (CRC), based on the consensus molecular subtype (CMS), stratifies patients with the poorest disease-free survival rates. It is characterized by a strong mesenchymal stromal cell (MSC) signature, wound healing-like inflammation and therapy resistance. We utilized 2D and 3D in vitro, in vivo, and ex vivo models to assess the impact of inflammation and stromal cells on immunosuppression in CMS4 CRC. RNA sequencing data from untreated stage II/III CRC patients showed enriched TNF-α signatures in CMS1 and CMS4 tumors. Secretome from TNF-α treated cancer cells induced an immunomodulatory and chemotactic phenotype in MSC and cancer-associated fibroblasts (CAFs). Macrophages in CRC tumours migrate and preferentially localise in stromal compartment. Inflammatory CRC secretome enhances expression of PD-L1 and CD47 on both human and murine stromal cells. We demonstrate that TNF-α-induced inflammation in CRC suppresses macrophage phagocytosis via stromal cells. We show that stromal cell-mediated suppression of macrophage phagocytosis is mediated in part through PD-1 signaling. These data suggest that re-stratification of CRC by CMS may reveal patient subsets with microsatellite stable tumors, particularly CMS4-like tumors, that may respond to immunotherapies.

Safety and Efficacy of Vicriviroc (MK-7690) in Combination With Pembrolizumab in Patients With Advanced or Metastatic Microsatellite Stable Colorectal Cancer

BACKGROUND

Pembrolizumab, a monoclonal antibody against PD-1, has shown limited efficacy in patients with microsatellite stable or mismatch repair proficient (MSS/pMMR) metastatic colorectal cancer (CRC). We evaluated vicriviroc (small-molecule C-C motif chemokine ligand 5 antagonist) plus pembrolizumab in patients with advanced or metastatic MSS/pMMR CRC.

PATIENTS AND METHODS

This open-label, phase 2 trial (NCT03631407) enrolled adults with histologically confirmed, locally advanced, unresectable or metastatic CRC that was MSS per local assessment. All patients had received previous treatment with standard therapies. Patients were randomized 1:1 to vicriviroc 150 mg orally once daily plus pembrolizumab 200 mg intravenously every 3 weeks or vicriviroc 250 mg orally once daily plus pembrolizumab 200 mg intravenously every 3 weeks for up to 35 cycles (2 years). Primary endpoints were the objective response rate (ORR) as assessed by the investigator per RECIST v1.1, dose-limiting toxicities (DLTs), adverse events (AEs), and discontinuations due to AEs.

RESULTS

Forty patients were enrolled and treated. ORR was 5% (95% CI, 0.1%-24.9%) in both treatment groups. There were no complete responses; 1 patient in each treatment group experienced a partial response. No patient in the vicriviroc 150 mg plus pembrolizumab group experienced a DLT. Two patients in the vicriviroc 250 mg plus pembrolizumab group experienced DLTs (1 grade 4 encephalopathy and 1 grade 4 pneumonitis).

CONCLUSION

The combination of vicriviroc at doses of 150 or 250 mg plus pembrolizumab 200 mg showed limited antitumor activity in patients with advanced or metastatic MSS/pMMR CRC. Toxicity with the combination was manageable.

Role of cancer-associated fibroblasts in colorectal cancer and their potential as therapeutic targets

Cancer-associated fibroblasts (CAFs) are mesenchymal cells in the tumor microenvironment (TME). CAFs are the most abundant cellular components in the TME of solid tumors. They affect the progression and course of chemotherapy and radiotherapy in various types of tumors including colorectal cancer (CRC). CAFs can promote tumor proliferation, invasion, and metastasis; protect tumor cells from immune surveillance; and resist tumor cell apoptosis caused by chemotherapy, resulting in drug resistance to chemotherapy. In recent years, researchers have become increasingly interested CAF functions and have conducted extensive research. However, compared to other types of malignancies, our understanding of the interaction between CRC cells and CAFs remains limited. Therefore, we searched the relevant literature published in the past 10 years, and reviewed the origin, biological characteristics, heterogeneity, role in the TME, and potential therapeutic targets of CAFs, to aid future research on CAFs and tumors.

Fibroblasts as Turned Agents in Cancer Progression

Differentiated epithelial cells reside in the homeostatic microenvironment of the native organ stroma. The stroma supports their normal function, their G0 differentiated state, and their expansion/contraction through the various stages of the life cycle and physiologic functions of the host. When malignant transformation begins, the microenvironment tries to suppress and eliminate the transformed cells, while cancer cells, in turn, try to resist these suppressive efforts. The tumor microenvironment encompasses a large variety of cell types recruited by the tumor to perform different functions, among which fibroblasts are the most abundant. The dynamics of the mutual relationship change as the sides undertake an epic battle for control of the other. In the process, the cancer "wounds" the microenvironment through a variety of mechanisms and attracts distant mesenchymal stem cells to change their function from one attempting to suppress the cancer, to one that supports its growth, survival, and metastasis. Analogous reciprocal interactions occur as well between disseminated cancer cells and the metastatic microenvironment, where the microenvironment attempts to eliminate cancer cells or suppress their proliferation. However, the altered microenvironmental cells acquire novel characteristics that support malignant progression. Investigations have attempted to use these traits as targets of novel therapeutic approaches.

CCL3 Promotes Proliferation of Colorectal Cancer Related with TRAF6/NF-κB Molecular Pathway

Chemokine C-C motif chemokine ligand 3 (CCL3) plays an important role in the invasion and metastasis of malignant tumors. For developing new therapeutic targets and antitumor drugs, the effect of chemokine CCL3 and the related cytokine network on colorectal cancer should be investigated. This study used cell, tissue, and animal experiments to prove that CCL3 is highly expressed in colorectal cancer and confirmed that CCL3 can promote the proliferation of cancer cells, and its expression is closely related to TRAF6/NF-κB molecular pathway. In addition, protein chip technology was used to examine colorectal cancer tissue samples and identify the key factors of chemokine CCL3 and the toll-like receptors/nuclear factor-κB (TLR/NF-κB) pathway in cancer and metastatic lymph nodes. Furthermore, the lentiviral vector technology was employed for transfection to construct interference and overexpression cell lines. The experimental results reveal the mechanism of CCL3 and TNF receptor-associated factor 6 (TRAF6)/NF-κB pathway-related factors and their effects on the proliferation of colon cancer cells. Finally, the expression and significance of CCL3 in colorectal cancer tissues and its correlation with clinical pathology were studied by immunohistochemistry. Also, the results confirmed that CCL3 and C-C motif chemokine receptor 5 (CCR5) were expressed in adjacent tissues, colorectal cancer tissues, and metastatic cancer. The expression level was correlated with the clinical stage and nerve invasion. The expression of chemokine CCL3 and receptor CCR5 was positively correlated with the expression of TRAF6 and NF-κB and could promote the proliferation, invasion, and migration of colorectal cancer cells through TRAF6 and NF-κB.

PARG suppresses tumorigenesis and downregulates genes controlling angiogenesis, inflammatory response, and immune cell recruitment

Chemokines are highly expressed in tumor microenvironment and play a critical role in all aspects of tumorigenesis, including the recruitment of tumor-promoting immune cells, activation of cancer-associated fibroblasts, angiogenesis, metastasis, and growth. Poly (ADP-ribose) polymerase (PARP) is a multi-target transcription regulator with high levels of poly(ADP-ribose) (pADPr) being reported in a variety of cancers. Furthermore, poly (ADP-ribose) glycohydrolase (PARG), an enzyme that degrades pADPr, has been reported to be downregulated in tumor tissues with abnormally high levels of pADPr. In conjunction to this, we have recently reported that the reduction of pADPr, by either pharmacological inhibition of PARP or PARG's overexpression, disrupts renal carcinoma cell malignancy in vitro. Here, we use 3 T3 mouse embryonic fibroblasts, a universal model for malignant transformation, to follow the effect of PARG upregulation on cells' tumorigenicity in vivo. We found that the overexpression of PARG in mouse allografts produces significantly smaller tumors with a delay in tumor onset. As downregulation of PARG has also been implicated in promoting the activation of pro-inflammatory genes, we also followed the gene expression profile of PARG-overexpressing 3 T3 cells using RNA-seq approach and observed that chemokine transcripts are significantly reduced in those cells. Our data suggest that the upregulation of PARG may be potentially useful for the tumor growth inhibition in cancer treatment and as anti-inflammatory intervention.

Tumor bud-derived CCL5 recruits fibroblasts and promotes colorectal cancer progression via CCR5-SLC25A24 signaling

Background

Tumor budding is included in the routine diagnosis of colorectal cancer (CRC) and is considered a tumor prognostic factor independent of TNM staging. This study aimed to identify the fibroblast-mediated effect of tumor bud-derived C–C chemokine ligand 5 (CCL5) on the tumor microenvironment (TME).

Methods

Recruitment assays and a human cytokine array were used to detect the main cytokines that CRC tumor buds secrete to recruit fibroblasts. siRNA transfection and inhibitor treatment were used to investigate the role of fibroblast CCL5 receptors in fibroblast recruitment. Subsequently, transcriptome sequencing was performed to explore the molecular changes occurring in fibroblasts upon stimulation with CCL5. Finally, clinical specimens and orthotopic xenograft mouse models were studied to explore the contribution of CCL5 to angiogenesis and collagen synthesis.

Results

Hematoxylin–eosin staining and immunochemistry revealed a higher number of fibroblasts at the invasive front of CRC tissue showing tumor budding than at sites without tumor budding. In vitro experiments demonstrated that CCL5 derived from tumor buds could recruit fibroblasts by acting on the CCR5 receptors on fibroblasts. Tumor bud-derived CCL5 could also positively regulate solute carrier family 25 member 24 (SLC25A24) expression in fibroblasts, potentially activating pAkt-pmTOR signaling. Moreover, CCL5 could increase the number of α-SMA^high CD90^high FAP^low fibroblasts and thus promote tumor angiogenesis by enhancing VEGFA expression and making fibroblasts transdifferentiate into vascular endothelial cells. Finally, the results also showed that CCL5 could promote collagen synthesis through fibroblasts, thus contributing to tumor progression.

Conclusions

At the invasive front of CRC, tumor bud-derived CCL5 can recruit fibroblasts via CCR5-SLC25A24 signaling, further promoting angiogenesis and collagen synthesis via recruited fibroblasts, and eventually create a tumor-promoting microenvironment. Therefore, CCL5 may serve as a potential diagnostic marker and therapeutic target for tumor budding in CRC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02300-w.

Assessment of the RANTES Level Correlation and Selected Inflammatory and Pro-Angiogenic Molecules Evaluation of Their Influence on CRC Clinical Features: A Preliminary Observational Study

Background and Objectives: Assessment of RANTES level and concentrations of inflammatory cytokines: programmed death ligand 1 (PD-L1), interferon gamma IFN-γ, tumor necrosis factor alpha (TNF-α), transforming growht factor β (TGF-β) (and angiogenesis factors: vascular endothelial growth factor A (VEGF-A) and vascular endothelial growth factor C (VEGF C) in tumor and margin tissues of colorectal cancer (CRC,) and evaluation of RANTES influence on histopathological parameters (microvessel density (MVD), budding, tumor-infiltrating lymphocytes (TILs)), in relation to patients’ clinical features. Materials and Methods: The study used 49 samples of tumor and margin tissues derived from CRC patients. To determinate the concentration of RANTES, PD-L1, IFN-γ, TNF-α, TGF-β, VEGF-A, and VEGF-C, we used the commercially available enzyme-linked immunosorbent assay kit. Additionally, RANTES and PD-L1 expression was assessed with the use of IHC staining in both tumor cells and TILS in randomly selected cases. MVD was assessed on CD34-stained specimens. The MVD and budding were assessed using a light microscope. Results: We found significantly higher levels of RANTES, PD-L1, IFN-γ, TNF-α, TGF-β, VEGF-A, and VEGF-C in the tumor in comparison with the margin. The RANTES tumor levels correlated significantly with those of PD-L1, TNF-α, TGF-β, VEGF-A, and VEGF-C. The RANTES margin levels were significantly associated with the margin levels of all proteins investigated—PD-L1, IFN-γ, TNF-α, TGF-β, VEGF-A, and VEGF-C. Additionally, we observed RANTES- and PD-L1-positive immunostaining in TILs. In a group of 24 specimens, 6 different CRC tumors were positive for RANTES and PD-L1 immunostaining. The IFN-gamma concentration in both tumor and margin and TGF-β in tumor correlated with TILs. TILs were negatively associated with the patients’ disease stage and N parameter. Conclusions: RANTES activity might be associated with angiogenesis, lymphogenesis, and immune escape in CRC. RANTES is an important chemokine that is a part of the chemokine–cytokine network involved in the modulation of TME composition in CRC. Further research may verify which processes are responsible for the associations observed in the study.

CCL5/CCR5 axis in human diseases and related treatments

To defense harmful stimuli or maintain the immune homeostasis, the body produces and recruits a superfamily of cytokines such as interleukins, interferons, chemokines etc. Among them, chemokines act as crucial regulators in defense systems. CCL5/CCR5 combination is known for facilitating inflammatory responses, as well as inducing the adhesion and migration of different T cell subsets in immune responses. In addition, recent studies have shown that the interaction between CCL5 and CCR5 is involved in various pathological processes including inflammation, chronic diseases, cancers as well as the infection of COVID-19. This review focuses on how CCL5/CCR5 axis participates in the pathological processes of different diseases and their relevant signaling pathways for the regulation of the axis. Moreover, we highlighted the gene therapy and chemotherapy studies for treating CCR5-related diseases, including the ongoing clinical trials. The barriers and perspectives for future application and translational research were also summarized.

Cancer-associated fibroblasts in colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of mortality among cancers. Many aspects of this cancer are under investigation to find established markers of diagnosis, prognosis, and also potential drug targets. In this review article, we are going to discuss the possible solution to all these aims by investigating the literature about cancer-associated fibroblasts (CAFs) involved in CRC. Moreover, we are going to review their interaction with the tumor microenvironment (TME) and vitamin D and their role in tumorigenesis and metastasis. Moreover, we are going to expand more on some markers produced by them or related to them including FAP, a-SMA, CXCL12, TGF- β, POSTN, and β1-Integrin. Some signaling pathways related to CAFs are as follows: FAK, AKT, activin A, and YAP/TAZ. Some genes related to the CAFs which are found to be possible therapeutic targets include COL3A1, JAM3, AEBP1 and, CAF-derived TGFB3, WNT2, and WNT54.

Maraviroc Prevents HCC Development by Suppressing Macrophages and the Liver Progenitor Cell Response in a Murine Chronic Liver Disease Model

Simple Summary

Liver stem cells and activated macrophages have been implicated as contributors to liver cancer; hence, reducing their abundance is a potential avenue for therapy. In this article, we demonstrate that Maraviroc, a drug approved for human use, reduces the liver stem cell response and macrophage activation in a mouse model of liver cancer. These findings underline the preventive potential of this drug in liver cancer, a deadly disease for which there are few effective treatments.

Abstract

Maraviroc (MVC), a CCR5 antagonist, reduces liver fibrosis, injury and tumour burden in mice fed a hepatocarcinogenic diet, suggesting it has potential as a cancer therapeutic. We investigated the effect of MVC on liver progenitor cells (LPCs) and macrophages as both have a role in hepatocarcinogenesis. Mice were fed the hepatocarcinogenic choline-deficient, ethionine-supplemented diet (CDE) ± MVC, and immunohistochemistry, RNA and protein expression were used to determine LPC and macrophage abundance, migration and related molecular mechanisms. MVC reduced LPC numbers in CDE mice by 54%, with a smaller reduction seen in macrophages. Transcript and protein abundance of LPC-associated markers correlated with this reduction. The CDE diet activated phosphorylation of AKT and STAT3 and was inhibited by MVC. LPCs did not express Ccr5 in our model; in contrast, macrophages expressed high levels of this receptor, suggesting the effect of MVC is mediated by targeting macrophages. MVC reduced CD45+ cells and macrophage migration in liver and blocked the CDE-induced transition of liver macrophages from an M1- to M2-tumour-associated macrophage (TAM) phenotype. These findings suggest MVC has potential as a re-purposed therapeutic agent for treating chronic liver diseases where M2-TAM and LPC numbers are increased, and the incidence of HCC is enhanced.

Chemokine-Directed Tumor Microenvironment Modulation in Cancer Immunotherapy

Chemokines are a large family of small chemotactic cytokines that coordinates immune cell trafficking. In cancer, they have a pivotal role in the migration pattern of immune cells into the tumor, thereby shaping the tumor microenvironment immune profile, often towards a pro-tumorigenic state. Furthermore, chemokines can directly target non-immune cells in the tumor microenvironment, including cancer, stromal and vascular endothelial cells. As such, chemokines participate in several cancer development processes such as angiogenesis, metastasis, cancer cell proliferation, stemness and invasiveness, and are therefore key determinants of disease progression, with a strong influence in patient prognosis and response to therapy. Due to their multifaceted role in the tumor immune response and tumor biology, the chemokine network has emerged as a potential immunotherapy target. Under the present review, we provide a general overview of chemokine effects on several tumoral processes, as well as a description of the currently available chemokine-directed therapies, highlighting their potential both as monotherapy or in combination with standard chemotherapy or other immunotherapies. Finally, we discuss the most critical challenges and prospects of developing targeted chemokines as therapeutic options.

Chemokine signaling in cancer-stroma communications

Cancer is a multi-faceted disease in which spontaneous mutation(s) in a cell leads to the growth and development of a malignant new organ that if left undisturbed will grow in size and lead to eventual death of the organism. During this process, multiple cell types are continuously releasing signaling molecules into the microenvironment, which results in a tangled web of communication that both attracts new cell types into and reshapes the tumor microenvironment as a whole. One prominent class of molecules, chemokines, bind to specific receptors and trigger directional, chemotactic movement in the receiving cell. Chemokines and their receptors have been demonstrated to be expressed by almost all cell types in the tumor microenvironment, including epithelial, immune, mesenchymal, endothelial, and other stromal cells. This results in chemokines playing multifaceted roles in facilitating context-dependent intercellular communications. Recent research has started to shed light on these ligands and receptors in a cancer-specific context, including cell-type specificity and drug targetability. In this review, we summarize the latest research with regards to chemokines in facilitating communication between different cell types in the tumor microenvironment.

CCR5 is a potential therapeutic target for cancer

INTRODUCTION

Chemokines and their cognate receptors play a major role in modulating inflammatory responses. Depending on their ligand binding, chemokine receptors can stimulate both immune activating and inhibitory signaling pathways. The CC chemokine receptor 5 (CCR5) promotes immune responses by recruiting immune cells to the sites of inflammation/tumor, and is involved in stimulating tumor cell proliferation, invasion and migration through various mechanisms. Moreover, CCR5 also contributes to an immune-suppressive tumor microenvironment by recruiting regulatory T cells and myeloid-derived suppressor cells facilitating tumor development and progression. In summary, cells expressing CCR5 modulate immune response and tumor progression. Expression of CCR5 is increased in various malignancies and associated with poor outcome. Experimental data show promising efficacy signals with CCR5 antagonists in preclinical tumor models. Therefore, CCR5 has been recognized as a potential therapeutic target for cancer.

AREAS COVERED

In this review, we focus on the role of CCR5 in cancer progression and discuss its impact and potential as a therapeutic target for cancer.

EXPERT OPINION

Beyond immune-checkpoint inhibitors, potentially synergistic immune-modulatory drugs such as CCR5 antagonists are a promising approach to enlarge our treatment armamentarium against cancer.

Complex Interplay of Genes Underlies Invasiveness in Fibrosarcoma Progression Model

Sarcomas are a heterogeneous group of mesenchymal tumours, with a great variability in their clinical behaviour. While our knowledge of sarcoma initiation has advanced rapidly in recent years, relatively little is known about mechanisms of sarcoma progression. JUN-murine fibrosarcoma progression series consists of four sarcoma cell lines, JUN-1, JUN-2, JUN-2fos-3, and JUN-3. JUN-1 and -2 were established from a single tumour initiated in a H2K/v-jun transgenic mouse, JUN-3 originates from a different tumour in the same animal, and JUN-2fos-3 results from a targeted in vitro transformation of the JUN-2 cell line. The JUN-1, -2, and -3 cell lines represent a linear progression from the least transformed JUN-2 to the most transformed JUN-3, with regard to all the transformation characteristics studied, while the JUN-2fos-3 cell line exhibits a unique transformation mode, with little deregulation of cell growth and proliferation, but pronounced motility and invasiveness. The invasive sarcoma sublines JUN-2fos-3 and JUN-3 show complex metabolic profiles, with activation of both mitochondrial oxidative phosphorylation and glycolysis and a significant increase in spared respiratory capacity. The specific transcriptomic profile of invasive sublines features very complex biological relationships across the identified genes and proteins, with accentuated autocrine control of motility and angiogenesis. Pharmacologic inhibition of one of the autocrine motility factors identified, Ccl8, significantly diminished both motility and invasiveness of the highly transformed fibrosarcoma cell. This progression series could be greatly valuable for deciphering crucial aspects of sarcoma progression and defining new prognostic markers and potential therapeutic targets.

Recombinant Bacteroides fragilis enterotoxin-1 (rBFT-1) promotes proliferation of colorectal cancer via CCL3-related molecular pathways

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide and stands among the leading causes of cancer-related deaths. Although deregulation of the microbiota in the gastrointestinal tract has been frequently described in CRC, very little is known about the precise molecular mechanisms by which bacteria and their toxins modulate the process of tumorigenesis and behavior of cancer cells. In this study, we produced recombinant Bacteroides fragilis enterotoxin-1 (rBFT1) and demonstrate that rBFT1 could promote cell proliferation in colorectal cancer cells and accelerate tumor growth in vivo. To identify the mechanisms, we further investigated CCL3/CCR5 and NF-κB pathway. We found that CCL3, CCR5, NF-κB, and TRAF-6 were dramatically upregulated after rBFT1 treatment, thus suggesting that the role of rBFT1 in CRC progression may be associated with CCL3/CCR5 and NF-κB pathways. Collectively, our results indicate that rBFT1 serves as a tumor promoter and plays a crucial role in inducing the proliferation of CRC via accelerating CCL3-related molecular pathway, thus giving insights into mechanistic underpinnings for the prevention and treatment of CRC.

Molecular Targets in Precision Chemoprevention of Colorectal Cancer: An Update from Pre-Clinical to Clinical Trials

Colorectal cancer (CRC) is one of the leading causes of cancer deaths worldwide. The initiation and progression of CRC is a multi-step process that proceeds via precursor lesions to carcinoma, with each stage characterized by its distinct molecular and tissue microenvironment changes. Precursor lesions of CRC, aberrant crypt foci, and adenoma exhibit drastic changes in genetic, transcriptomic, and proteomic profiles compared to normal tissue. The identification of these changes is essential and provides further validation as an initiator or promoter of CRC and, more so, as lesion-specific druggable molecular targets for the precision chemoprevention of CRC. Mutated/dysregulated signaling (adenomatous polyposis coli, β-catenin, epidermal growth factor receptor, V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS), tumor protein53, Akt, etc.), inflammatory (cyclooxygenase-2, microsomal prostaglandin E synthase-1, inducible nitric oxide synthase, and other pro-inflammatory mediators), and metabolic/growth factor (fatty acid synthase, β-Hydroxy β-methylglutaryl-CoA reductase, and ornithine decarboxylase) related targets are some of the well-characterized molecular targets in the precision chemoprevention of CRC. In this review, we discuss precursor-lesion specific targets of CRC and the current status of pre-clinical studies regarding clinical interventions and combinations for better efficacy and safety toward future precision clinical chemoprevention. In addition, we provide a brief discussion on the usefulness of secondary precision chemopreventive targets for tertiary precision chemoprevention to improve the disease-free and overall survival of advanced stage CRC patients.

3D Tumor Models and Their Use for the Testing of Immunotherapies

Over the past decade, immunotherapy has become a powerful and evident tool in the fight against cancers. Notably, the rise of checkpoint blockade using monoclonal antibodies (anti-CTLA4, anti-PD1) to avoid interaction between inhibitory molecules allowed the betterment of patient care. Indeed, immunotherapies led to increased overall survival in forms of cutaneous melanoma or lung cancer. However, the percentage of patients responding varies from 20 to 40% depending on the type of cancer and on the expression of the target molecules by the tumor. This is due to the tumor microenvironment which allows the acquisition of resistance mechanisms to immunotherapies by tumor cells. These are closely linked to the architecture and cellular composition of the tumor microenvironment. This one acts on different parameters such as the immune cells infiltrate its composition and therefore, favors the recruitment of immunosuppressive cells as well as the tumor expression of checkpoint inhibitors such as Programmed Death Ligand-1 (PD-L1). Therefore, the analysis and modeling of the complexity of the microenvironment is an important parameter to consider, not only in the search for new therapies but also for the identification and stratification of patients likely to respond to immunotherapy. This is why the use of 3D culture models, reflecting the architecture and cellular composition of a tumor, is essential in immuno-oncology studies. Nowadays, there are several 3-D culture methods such as spheroids and organoids, which are applicable to immuno-oncology. In this review we evaluate 3D culture models as tools for the development of treatments in the field of immuno-oncology.

Maraviroc, tenofovir disoproxil fumarate and dapivirine, activate progesterone receptor B in the absence of progestogens

Antiretroviral therapy has slowed the HIV/AIDS pandemic and is currently being used as a prophylactic measure for individuals at high risk of infection. However, concerns over adverse effects of long-term use need to be explored. We hypothesize that this may occur, at least in part, through off-target effects via select steroid receptors (SRs) that broadly regulate multiple physiological processes. We investigated the effects of maraviroc (MVC), tenofovir disoproxil fumarate (TDF), and dapivirine (DPV) on progesterone receptor B (PR-B) transcriptional activity. We found that MVC and TDF activate PR-B transcription in the absence of progestogens on a PR-regulated promoter reporter construct and on endogenous PR-regulated genes. MVC and TDF exhibited no direct binding to PR-B; however, increased PR-B phosphorylation was detected with TDF but not MVC. DPV transactivated gilz and ptgs2 in the absence of progestogens and exhibited PR-B binding while showing no effects on phosphorylation, suggesting that it may activate PR-B through a direct mechanism. Our study shows that potential off-target immunomodulatory effects of MVC, TDF and DPV occur in vitro and these are most likely mediated by different mechanisms of PR-B activation.

Antineoplastic effects of targeting CCR5 and its therapeutic potential for colorectal cancer liver metastasis

Purpose

Liver metastasis is observed in up to 50% of colorectal cancer (CRC) patients. Available treatment options are limited and disease recurrence is often. Chemokine receptor 5 (CCR5) has attracted attention as novel therapeutic target for treating cancers. In this study, we reinforced the importance of CCR5 as therapeutic target in CRC and its liver metastasis by applying in vitro, in vivo and clinical investigations.

Methods

By targeting CCR5 via siRNAs or an FDA approved antagonist (maraviroc), we investigated the ensuing antineoplastic effects in three CRC cell lines. An animal model for CRC liver metastasis was used to evaluate time-dependent expressional modulation of the CCR5 axis by cDNA microarray. The model was also used to evaluate the in vivo efficacy of targeting CCR5 by maraviroc. Circulatory and tumor associated levels of CCR5 and its cognate ligands (CCL3, CCL4, CCL5) were analyzed by ELISA, qRT-PCR and immunohistochemistry.

Results

Targeting the CCR5 inhibited proliferative, migratory and clonogenic properties and interfered with cell cycle-related signaling cascades. In vivo findings showed significant induction of the CCR5 axis during the early liver colonization phase. Treatment with maraviroc significantly inhibited CRC liver metastasis in the animal model. Differential expression profiles of circulatory and tumor associated CCR5/ligands were observed in CRC patients and healthy controls.

Conclusion

The findings indicate that targeting the CCR5 axis can be an effective strategy for treating CRC liver metastasis.

Electronic supplementary material

The online version of this article (10.1007/s00432-020-03382-9) contains supplementary material, which is available to authorized users.

Colorectal Cancer and Bone Tissue: Fantastic Relations and Where to Find Them

Colorectal cancer (CRC) is the third most common cancer worldwide. There is a need for the early diagnosis of CRC for a better prognostic outcome. It is, therefore, crucial to understand the CRC pathogenesis in all its aspects. In many cases, one of the main causes of cancer-related deaths is the presence of metastases. In this context, an often overlooked aspect is the metastatic tropism, since CRC, like other cancers, is more prone to metastasize some organs rather than others. Beyond the liver and lung, and differently from other types of cancers, a not usual site of CRC metastases is the bone. However, it may assume a crucial role in the development and the outcome of the disease. Therefore, this review aims to discuss the complex relations between bone markers and CRC pathogenesis, suggesting the use of these molecules as potential targets for therapeutic purposes. Different osteogenic molecules, some of whom are growth factors and are implicated in the different osteogenic pathways, have been proved to also be involved in CRC progression. Some of them are oncogenes, while others oncosuppressors, and in a future perspective, some of them may represent new potential CRC biomarkers.

The CCL5/CCR5 Axis in Cancer Progression

Tumor cells can “hijack” chemokine networks to support tumor progression. In this context, the C-C chemokine ligand 5/C-C chemokine receptor type 5 (CCL5/CCR5) axis is gaining increasing attention, since abnormal expression and activity of CCL5 and its receptor CCR5 have been found in hematological malignancies and solid tumors. Numerous preclinical in vitro and in vivo studies have shown a key role of the CCL5/CCR5 axis in cancer, and thus provided the rationale for clinical trials using the repurposed drug maraviroc, a CCR5 antagonist used to treat HIV/AIDS. This review summarizes current knowledge on the role of the CCL5/CCR5 axis in cancer. First, it describes the involvement of the CCL5/CCR5 axis in cancer progression, including autocrine and paracrine tumor growth, ECM (extracellular matrix) remodeling and migration, cancer stem cell expansion, DNA damage repair, metabolic reprogramming, and angiogenesis. Then, it focuses on individual hematological and solid tumors in which CCL5 and CCR5 have been studied preclinically. Finally, it discusses clinical trials of strategies to counteract the CCL5/CCR5 axis in different cancers using maraviroc or therapeutic monoclonal antibodies.

HIV-1, HAART and cancer: A complex relationship

HIV infected people are at higher risk of developing cancer, although it is globally diminished in the era of highly active antiretroviral treatment (HAART). Recently, antioncogenic properties of some HAART drugs were discovered. We discuss the role of HAART in the prevention and improvement of treatment outcomes of cancers in HIV-infected people. We describe different trends in HAART-cancer relationships: cancer-predisposing as well as cancer-preventing. We cover the roles of particular drug regimens in cancer prevention. We also describe the causes of cancer treatment with HAART drugs in HIV-negative people, including ongoing clinical studies that may directly point to a possible independent anti-oncogenic activity of HAART drugs. We conclude that despite potent antioncogenic activities of every class of HAART drugs reported in preclinical models, the evidence to date indicates that their independent clinical impact in HIV-infected people is limited. Improved cancer prevention strategies besides HAART are needed to reduce HIV-cancer-related mortality.

Crosstalk Between Prostate Cancer Cells and Tumor-Associated Fibroblasts Enhances the Malignancy by Inhibiting the Tumor Suppressor PLZF

Although prostate cancer is clinically manageable during the early stages of progression, metastatic progression severely compromises the prognosis and leads to mortality. Constitutive activation of STAT3 has been connected to prostate cancer malignancy, and abolishing the STAT3 activity may diminish tumor growth and metastasis. However, its suppressor genes and pathways have not been well established. In this study, we show that promyelocytic leukemia zinc finger (PLZF) has a putative tumor-suppressor function in prostate cancer by inhibiting phosphorylation of STAT3. Compared with a benign prostate, high-grade prostate cancer patient tissue was negatively correlated with PLZF expression. PLZF depletion accelerated proliferation and survival, migration, and invasion in human prostate cancer cells. Mechanistically, we demonstrated a novel role of PLZF as the transcriptional regulator of the tyrosine phosphatase SHP-1 that inhibits the oncogenic JAKs–STAT3 pathway. These results suggest that the collapse of PLZF expression by the CCL3 derived from fibroblasts accelerates the cell migration and invasion properties of prostate cancer cells. Our results suggest that increasing PLZF could be an attractive strategy for suppressing prostate cancer metastasis as well as for tumor growth.

CCR5 and CCR5Δ32 in bacterial and parasitic infections: Thinking chemokine receptors outside the HIV box

The CCR5 molecule was reported in 1996 as the main HIV-1 co-receptor. In that same year, the CCR5Δ32 genetic variant was described as a strong protective factor against HIV-1 infection. These findings led to extensive research regarding the CCR5, culminating in critical scientific advances, such as the development of CCR5 inhibitors for the treatment of HIV infection. Recently, the research landscape surrounding CCR5 has begun to change. Different research groups have realized that, since CCR5 has such important effects in the chemokine system, it could also affect other different physiological systems. Therefore, the effect of reduced CCR5 expression due to the presence of the CCR5Δ32 variant began to be further studied. Several studies have investigated the role of CCR5 and the impacts of CCR5Δ32 on autoimmune and inflammatory diseases, various types of cancer, and viral diseases. However, the role of CCR5 in diseases caused by bacteria and parasites is still poorly understood. Therefore, the aim of this article is to review the role of CCR5 and the effects of CCR5Δ32 on bacterial (brucellosis, osteomyelitis, pneumonia, tuberculosis and infection by Chlamydia trachomatis) and parasitic infections (toxoplasmosis, leishmaniasis, Chagas disease and schistosomiasis). Basic information about each of these infections was also addressed. The neglected role of CCR5 in fungal disease and emerging studies regarding the action of CCR5 on regulatory T cells are briefly covered in this review. Considering the "renaissance of CCR5 research," this article is useful for updating researchers who develop studies involving CCR5 and CCR5Δ32 in different infectious diseases.

The G protein coupled receptor CCR5 in cancer

The G coupled protein receptor CC chemokine receptor type 5 (CCR5) has the unusual characteristic in humans of being a developmentally non-essential gene that participates in several pathological processes including infection with HIV (Dean et al., 1996; Gupta et al., 2019; Samson et al., 1996), progression of stroke (Joy et al., 2019), osteoporosis (Xie et al., 2019) and the metastasis of cancer (Jiao et al., 2018; Velasco-Velazquez et al., 2012, 2014) (Reviewed in: Jiao, Nawab, et al., 2019; Jiao, Wang, & Pestell, 2019). The importance of CCR5 in HIV led to recent genetic engineering of humans to recreate a non-functional CCR5 gene. Thus, although the application of gene-editing tools, to manipulate human embryos is prohibited in the United States, and China. at the Second International Summit on Human Genome Editing in Hong Kong (http://www.nationalacademies.org/), it was claimed that CRISPR-Cas9 systems had been used to edit the CCR5 gene in twin baby girls. The importance of CCR5 in stroke has led to clinical trials using maraviroc (NCT03172026). The key function of CCR5 in cancer metastasis and homing (Jiao et al., 2018; Jiao, Nawab, et al., 2019; Velasco-Velazquez et al., 2012, 2014) has led to three active clinical trials for metastatic cancer using CCR5 antagonists (Jiao, Nawab, et al., 2019; Jiao, Wang, & Pestell, 2019). Thus, it was surprising to find that the all-cause mortality rate in individuals who are homozygous for the CCR5△32 allele in the United Kingdom normal population was increased >20% increase, with an almost 2 year reduction overall lifespan (Wei & Nielsen, 2019). The current review herein discusses the distinct functions of CCR5 in human disease and potential avenues for further research.

A combination of inhibitors of glycolysis, glutaminolysis and de novo fatty acid synthesis decrease the expression of chemokines in human colon cancer cells

Lonidamine, 6-Diazo-5-oxo-L-norleucine (DON) and orlistat are well known inhibitors of glycolysis, glutaminolysis and of de novo fatty acid synthesis, respectively. Although their antitumor effects have been explored in detail, the potential inhibition of the malignant metabolic phenotype and its influence on the expression of chemokines and growth factors involved in colon cancer, have not been previously reported to the best of our knowledge. In the present study, dose-response curves with orlistat, lonidamine or DON were generated from cell viability assays conducted in SW480 colon cancer cells. In addition, the synergistic effect of these compounds was evaluated in SW480 human colon cancer cells. The determination of the doses used for maximum synergistic efficacy led to the exploration of the mRNA levels of the target genes hexokinase-2 (HK2), glutaminase-1 (GLS-1) and fatty acid synthase (FASN) in human SW480 and murine CT26.WT colon cancer cells. The cell viability was evaluated following transfection with small interfering (si)RNA targeting these genes and was assessed with trypan blue. The expression levels of chemokines and growth factors were quantified in the supernatant of SW480 cells with LEGENDplex™. The combination of lonidamine, DON and orlistat resulted in a synergistic cytotoxic effect and induced the transcription of the corresponding gene targets but their corresponding proteins were actually downregulated. The downregulation of the expression levels of HK2, GLS-1 and FASN following transfection of the cells with the corresponding siRNA sequences decreased their viability. The treatment significantly reduced the expression levels of 9 chemokines [interleukin-9, C-X-C motif chemokine ligand (CXCL) 10, eotaxin, chemokine ligand (CCL) 9, CXCL5, CCL20, CXCL1, CXCL11 and CCCL4] and one growth factor (stem cell factor). These changes were associated with decreased phosphorylated-nuclear factor κB-p65. The data demonstrate that lonidamine, DON and orlistat in combination reduce the expression levels of chemokines and growth factors in colon cancer cells. Additional research is required to investigate the exact way by which both tumor and stromal cells regulate the expression levels of chemokines and growth factors.

Recent Advances Targeting CCR5 for Cancer and Its Role in Immuno-Oncology

Experiments of nature have revealed the peculiar importance of the G-protein-coupled receptor, C-C chemokine receptor type 5 (CCR5), in human disease since ancient times. The resurgence of interest in heterotypic signals in the onset and progression of tumorigenesis has led to the current focus on CCR5 as an exciting new therapeutic target for metastatic cancer with clinical trials now targeting breast and colon cancer. The eutopic expression of CCR5 activates calcium signaling and thereby augments regulatory T cell (Treg) differentiation and migration to sites of inflammation. The misexpression of CCR5 in epithelial cells, induced upon oncogenic transformation, hijacks this migratory phenotype. CCR5 reexpression augments resistance to DNA-damaging agents and is sufficient to induce cancer metastasis and "stemness". Recent studies suggest important cross-talk between CCR5 signaling and immune checkpoint function. Because CCR5 on Tregs serves as the coreceptor for human immunodeficiency virus (HIV) entry, CCR5-targeted therapeutics used in HIV, [small molecules (maraviroc and vicriviroc) and a humanized mAb (leronlimab)], are now being repositioned in clinical trials as cancer therapeutics. As CCR5 is expressed on a broad array of tumors, the opportunity for therapeutic repositioning and the rationale for combination therapy approaches are reviewed herein.

The Diagnostic Significance of PDGF, EphA7, CCR5, and CCL5 Levels in Colorectal Cancer

In this study, we compared the levels of C-C chemokine receptor type 5 (CCR5), C-C motif chemokine ligand 5 (CCL5), platelet-derived growth factor (PDGF), and EphrinA7 (EphA7) in patients with colorectal carcinoma and healthy controls in order to investigate the significance and usability of these potential biomarkers in early diagnosis of colorectal cancer. The study included 70 colorectal carcinoma patients and 40 healthy individuals. The CCR5, CCL5, PDGF, and EphA7 levels were measured using ELISA in blood samples. PDGF-BB, EphA7, CCR5, and CCL5 levels of the patients with colorectal carcinoma were significantly higher compared to the control group (p < 0.001 for each comparison). Our logistic regression analysis (the area under the curve was 0.958) supports the notion that PDGF-BB, EphA7, and CCL5 are potential biomarkers for the diagnosis of colon cancer. The sensitivity, specificity, and positive and negative predictive values were found to be 87.9%, 87.5%, 92.1%, and 81.4%, respectively. To our knowledge, this is the first study that investigates the relationship between colorectal carcinoma and the four biomarkers CCL5, CCR5, PDGF, and EphA7. The significantly elevated levels of all these parameters in the patient group compared to the healthy controls indicate that they can be used for the early diagnosis of colorectal carcinoma.

CCR5 status and metastatic progression in colorectal cancer

Multiple reports have highlighted the importance of the local immunological cellular composition (i.e. the density of effector T cells and macrophage polarization state) in predicting clinical outcome in advanced metastatic stage of colorectal cancer. However, in spite of the general association between a high effector T cell density and improved outcome, our recent work has revealed a specific lymphocyte-driven cancer cell-supporting signal. Indeed, lymphocyte-derived CCL5 supports CCR5-positive tumor cell proliferation and thereby fosters tumor growth in metastatic liver lesions. Upon systematic analysis of CCR5 expression by tumor cells using immunohistochemistry, we observed that the intensity of CCR5 increases with primary tumor size and peaks in T4 tumors. In liver metastases however, though CCR5 expression intensity is globally heightened compared to primary tumors, alterations in the expression patterns appear, leading to “patchiness” of the stain. CCR5 patchiness is, therefore, a signature of liver metastases in our cohort (n = 97 specimens) and relates to globally decreased expression intensity, but does not influence the extent of the response to CCR5 inhibitor Maraviroc in patients. Moreover, CCR5 patchiness relates to a poor immune landscape characterized by a low cytotoxic-to-regulatory T cell ratio at the invasive margin and enriched cellular and molecular markers of macrophage M2 polarization. Finally, because higher numbers of PD-1- and CTLA-4-positive cells surround tumors with patchy CCR5 expression, one can speculate that these tumors potentially respond to immune checkpoint blockade. This hypothesis is corroborated by the prolonged disease-free survival and disease-specific survival observed in patients with low gene expression of CCR5 in metastases from two publically available cohorts. These observations highlight the complex role of the CCL5-CCR5 axis in CRC metastatic progression and warrant further investigations.

Low-Dose Maraviroc, an Antiretroviral Drug, Attenuates the Infiltration of T Cells into the Central Nervous System and Protects the Nigrostriatum in Hemiparkinsonian Monkeys

Parkinson's disease (PD) is the most common neurodegenerative movement disorder in humans. Despite intense investigation, no effective therapy is available to stop the progression of this disease. It is becoming clear that both innate and adaptive immune responses are active in PD. Accordingly, we have reported a marked increase in RANTES and eotaxin, chemokines that are involved in T cell trafficking, in vivo in the substantia nigra (SN) and the serum of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-intoxicated hemiparkinsonian monkeys. Because RANTES and eotaxin share a common receptor, CCR5, we examined the efficacy of maraviroc, an inhibitor of CCR5 and a Food and Drug Administration-approved drug against HIV infection, in hemiparkinsonian rhesus monkeys. First, we found glial limitans injury, loss of GFAP immunostaining, and infiltration of T cells across the endothelial monolayer in SN of hemiparkinsonian monkeys. However, oral administration of a low dose of maraviroc protected glia limitans partially, maintained the integrity of endothelial monolayer, reduced the infiltration of T cells, attenuated neuroinflammation, and decreased α-synucleinopathy in the SN. Accordingly, maraviroc treatment also protected both the nigrostriatal axis and neurotransmitters and improved motor functions in hemiparkinsonian monkeys. These results suggest that low-dose maraviroc and other CCR5 antagonists may be helpful for PD patients.

Formation of the Immunosuppressive Microenvironment of Classic Hodgkin Lymphoma and Therapeutic Approaches to Counter It

Classic Hodgkin lymphoma (cHL) is characterized by a few tumor cells surrounded by a protective, immunosuppressive tumor microenvironment composed of normal cells that are an active part of the disease. Hodgkin and Reed-Sternberg (HRS) cells evade the immune system through a variety of different mechanisms. They evade antitumor effector T cells and natural killer cells and promote T cell exhaustion. Using cytokines and extracellular vesicles, they recruit normal cells, induce their proliferation and "educate" (i.e. reprogram) them to become immunosuppressive and protumorigenic. Therefore, alternative treatment strategies are being developed to target not only tumor cells but also the tumor microenvironment. Here we summarize current knowledge on the ability of HRS cells to build their microenvironment and to educate normal cells to become immunosuppressive. We also describe therapeutic strategies to counteract formation of the tumor microenvironment and related processes leading to T cell exhaustion and repolarization of immunosuppressive tumor-associated macrophages.

Prognostic value of immunoexpression of CCR4, CCR5, CCR7 and CXCR4 in squamous cell carcinoma of tongue and floor of the mouth

Background

Diverse studies have evidenced that chemokines can play a critical role in pathogenesis of oral squamous cell carcinoma (SCC). The main chemokines involved in oral carcinogenesis, tumor invasion and metastasis are CCR4, CCR5, CCR7 and CXCR4, and our aim was to evaluate the prognostic value of the immunoexpression of these chemokines in SCC of tongue and floor of the mouth.

Material and Methods

A retrospective descriptive study of the immunohistochemical expression of CCR4, CCR5, CCR7 and CXCR4 in paraffin-embedded samples of 124 patients with SCC of the tongue and floor of the mouth was performed, considering 98 cases from Brazil and 26 cases from Chile. Associations between variables were analyzed using chi-square test. Survival curves were performed using the Kaplan-Meier method and compared with long-rank test. For multivariate survival analysis, the Cox hazard model was established. The level of significance established was p≤0.05.

Results

The statistical analysis showed that samples with well or moderate WHO model differentiation (p=0.001) and a high expression of CCR5 (p=0.05) were significantly associated with a higher disease specific survival, which were also observed in Cox´s multivariate analysis (p=0.01). A higher expression of CCR7 (p=0.01) interfered significantly in disease-free survival in univariate analysis and in Cox´s multivariate analysis (p=0.05).

Conclusions

These results support additional evidence, showing that chemokine receptors CCR5 and CCR7 are helpful as biomarkers of poor prognosis in patients with SCC of the tongue and floor of the mouth.

Key words:Oral squamous cell carcinoma, prognosis, survival, chemokine receptor.

Bone marrow-derived mesenchymal stem cells promote colorectal cancer progression via CCR5

Mesenchymal stem cells (MSCs) are recruited from BM to the stroma of developing tumors, where they serve as critical components of the tumor microenvironment by secreting growth factors, cytokines, and chemokines. The role of MSCs in colorectal cancer (CRC) progression was controversial. In this study, we found that C-C chemokine receptor type 5 (CCR5) ligands (i.e., C-C motif chemokine ligand 3 (CCL3), CCL4, and CCL5) were highly produced from MSCs using a chemokine array screening with conditioned media from the cultured human MSCs. A relatively strong CCR5 expression could be detected within the cytoplasm of several CRC cell lines. Regarding the effect of MSC, we found that the xenografts in which CCR5-overexpressing HCT116 cells were inoculated into immunocompromised mice were highly promoted in vivo by a mixture with MSCs. Notably, the CCR5 inhibitor, maraviroc, significantly abolished the MSC-induced tumor growth in vivo. In human clinical specimens (n = 89), 20 cases (29%) were high for CCR5, whereas 69 cases (71%) were low. Statistical analyses indicated that CCR5 expression in primary CRC was associated with CRC patients’ prognosis. Especially, stage III/IV patients with CCR5-high CRCs exhibited a significantly poorer prognosis than those with CCR5-low CRCs. Furthermore, we investigated the effects of preoperative serum CCR5 ligands on patients’ prognosis (n = 114), and found that CRC patients with high serum levels of CCL3 and CCL4 exhibited a poorer prognosis compared to those with low levels of CCL3 and CCL4, while there was no association between CCL5 and prognosis. These results suggest that the inhibition of MSC–CRC interaction by a CCR5 inhibitor could provide the possibility of a novel therapeutic strategy for CRC, and that serum levels of CCL3 and CCL4 could be predictive biomarkers for the prognosis of CRC patients.

CCR5 blockage by maraviroc: a potential therapeutic option for metastatic breast cancer

PURPOSE

Bone metastasis is observed in up to 70% of breast cancer patients. The currently available treatment options are palliative in nature. Chemokine receptor 5 (CCR5) has gained attention as therapeutic target in various malignancies. Here, we investigated the effects of targeting CCR5 by its antagonist maraviroc in metastatic breast cancer cells.

METHODS

In response to maraviroc exposure, cytotoxicity was assessed using an MTT proliferation assay, whereas the effects on colony formation and migration were assessed using colony formation, transwell chamber migration and scratch wound healing assays, respectively. Apoptosis-related activities were investigated using nuclear staining, annexin-V FITC staining and Western blotting. Cell cycle changes were analysed using flow cytometry and qRT-PCR for cell cycle relevant genes. A nude rat model for breast cancer bone metastasis was used to evaluate the in vivo efficacy of CCR5 targeting by maraviroc. Circulatory levels of the three cognate ligands for CCR5 (CCL3, CCL4, CCL5) were analysed in sera of breast cancer patients using ELISA.

RESULTS

We found that blockade of CCR5 attenuated the proliferation, colony formation and migration of metastatic breast cancer cells, and induced apoptosis and arrest in the G1 phase of the cell cycle. Expression profiling highlighted the involvement of cell cycle related signalling cascades. We also found that treatment with maraviroc significantly inhibited bone metastasis in nude rats implanted with MDA-MB-231 breast cancer cells. Finally, we found that the circulatory levels of three cognate ligands for the CCR5 receptor varied between breast cancer patients and healthy controls.

CONCLUSION

Our findings indicate that targeting CCR5 may be an effective strategy to combat breast cancer bone metastasis.

CCR5 antagonism by maraviroc inhibits Hodgkin lymphoma microenvironment interactions and xenograft growth

Classic Hodgkin lymphoma tumor cells express a functional CCR5 receptor, and tumor tissues express high CCL5 levels, suggesting that CCL5-CCR5 signaling is involved in tumor-microenvironment formation and tumor growth. Using the CCR5 antagonist, maraviroc, and a neutralizing anti-CCL5 antibody, we found that CCL5 secreted by classic Hodgkin lymphoma cells recruited mesenchymal stromal cells and monocytes. The “education” of mesenchymal stromal cells by tumor cell-conditioned medium enhanced mesenchymal stromal cells’ proliferation and CCL5 secretion. In turn, educated mesenchymal stromal cell-conditioned medium increased the clonogenic growth of tumor cells and monocyte migration, but these effects were reduced by maraviroc. Monocyte education by tumor cell-conditioned medium induced their growth and reprogrammed them towards immunosuppressive tumor-associated macrophages that expressed IDO and PD-L1 and secreted IL-10, CCL17 and TGF-β. Educated monocyte-conditioned medium slowed the growth of phytohemagglutinin-activated lymphocytes. Maraviroc decreased tumor cell growth and synergized with doxorubicin and brentuximab vedotin. A three-dimensional heterospheroid assay showed that maraviroc counteracted both the formation and viability of heterospheroids generated by co-cultivation of tumor cells with mesenchymal stromal cells and monocytes. In mice bearing tumor cell xenografts, maraviroc reduced tumor growth by more than 50% and inhibited monocyte accumulation, without weight loss. Finally, in classic Hodgkin lymphoma human tumor tissues, CCL5 and CD68 expression correlated positively, and patients with high CCL5 levels had poor prognosis. In conclusion, since the present challenges are to find molecules counteracting the formation of the immunosuppressive tumor microenvironment or new, less toxic drug combinations, the repurposed drug maraviroc may represent a new opportunity for classic Hodgkin lym phoma treatment.

Pancreatic carcinoma cells colonizing the liver modulate the expression of their extracellular matrix genes

Liver is the main target of pancreatic ductal adenocarcinoma (PDAC) metastasis. Here, a rat model was used for analysing gene expression modulations during liver colonization. ASML PDAC cells were injected to isogenic rats and re-isolated at various stages of liver colonization for RNA isolation or re-cultivation. Microarrays were used for analysing mRNA and miRNA profiles of expres­sion. The results were partially confirmed by (q) RT-PCR and western blot. Selected genes were knocked down by siRNA transfection and the resulting cell behaviour was analysed. The ratio of up- and down regulated genes decreased from 20:1 (early stage) to 1.2:1 (terminal stage). Activation of cancer relevant gene categories varied between stages of liver colonization, with a nadir in the intermediate stage. The cells' environment triggered up to hundredfold changed expression for collagens, matrix metalloproteinases and chemokines. These modulations in mRNA expression were related to respective changes at miRNA levels. Gene expression knockdown of Mmp2 and Ccl20, which were highly modulated in vivo, was correlated with reduced prolif­eration and migration in vitro. Thus, target genes and temporal alterations in expression were identified, which can serve as basis for future therapeutic or diagnostic purposes.

Inhibition of the CCL5/CCR5 Axis against the Progression of Gastric Cancer

Despite the progress made in molecular and clinical research, patients with advanced-stage gastric cancer (GC) have a bad prognosis and very low survival rates. Furthermore, it is challenging to find the complex molecular mechanisms that are involved in the development of GC, its progression, and its resistance to therapy. The interactions of chemokines, also known as chemotactic cytokines, with their receptors regulate immune and inflammatory responses. However, updated research demonstrates that cancer cells subvert the normal chemokine role, transforming them into fundamental constituents of the tumor microenvironment (TME) with tumor-promoting effects. C-C chemokine ligand 5 (CCL5) is a chemotactic cytokine, and its expression and secretion are regulated in T cells. C-C chemokine receptor type 5 (CCR5) is expressed in T cells, macrophages, other leukocytes, and certain types of cancer cells. The interaction between CCL5 and CCR5 plays an active role in recruiting leukocytes into target sites. This review summarizes recent information on the role of the CCL5 chemokine and its receptor CCR5 in GC cell proliferation, metastasis formation, and in the building of an immunosuppressive TME. Moreover, it highlights the development of new therapeutic strategies to inhibit the CCL5/CCR5 axis in different ways and their possible clinical relevance in the treatment of GC.

Hyaluronan, Cancer-Associated Fibroblasts and the Tumor Microenvironment in Malignant Progression

This review summarizes the roles of CAFs in forming a “cancerized” fibrotic stroma favorable to tumor initiation and dissemination, in particular highlighting the functions of the extracellular matrix component hyaluronan (HA) in these processes. The structural complexity of the tumor and its host microenvironment is now well appreciated to be an important contributing factor to malignant progression and resistance-to-therapy. There are multiple components of this complexity, which include an extensive remodeling of the extracellular matrix (ECM) and associated biomechanical changes in tumor stroma. Tumor stroma is often fibrotic and rich in fibrillar type I collagen and hyaluronan (HA). Cancer-associated fibroblasts (CAFs) are a major source of this fibrotic ECM. CAFs organize collagen fibrils and these biomechanical alterations provide highways for invading carcinoma cells either under the guidance of CAFs or following their epithelial to mesenchymal transition (EMT). The increased HA metabolism of a tumor microenvironment instructs carcinoma initiation and dissemination by performing multiple functions. The key effects of HA reviewed here are its role in activating CAFs in pre-malignant and malignant stroma, and facilitating invasion by promoting motility of both CAFs and tumor cells, thus facilitating their invasion. Circulating CAFs (cCAFs) also form heterotypic clusters with circulating tumor cells (CTC), which are considered to be pre-cursors of metastatic colonies. cCAFs are likely required for extravasation of tumors cells and to form a metastatic niche suitable for new tumor colony growth. Therapeutic interventions designed to target both HA and CAFs in order to limit tumor spread and increase response to current therapies are discussed.

Chemokines and cancer: new immune checkpoints for cancer therapy

The current review focuses on two chemokine-chemokine receptor interactions: CXCL10-CXCR3 and CCL1-CCR8. We show that CXCL10 acts on CD4+ and CD8+ T cells to enhance anti-tumor immunity, and explore the translational perspectives of these findings. As for CCR8 very recently, we identified a novel subset of CCR8+CD4+FOXp3+ regulatory T cells (T_reg) that are major drivers of immune regulation. We observed that one of the four CCR8 ligands, CCL1, produced by these cells, potentiates their suppressive activity via induction of CCR8, FOXp3, CD39, Granzyme-B, and IL-10 in a positive feedback mechanism, making them master drivers of immune regulation. Collectively, this suggests blocking the CCR8-CCL1 interaction, alone or combined with other immune checkpoint inhibitors, as an approach to treat malignant diseases.

The Role of Hypoxia in Glioblastoma Invasion

Glioblastoma multiforme (GBM), a grade IV astrocytoma, is the most common and deadly type of primary malignant brain tumor, with a patient's median survival rate ranging from 15 to 17 months. The current treatment for GBM involves tumor resection surgery based on MRI image analysis, followed by radiotherapy and treatment with temozolomide. However, the gradual development of tumor resistance to temozolomide is frequent in GBM patients leading to subsequent tumor regrowth/relapse. For this reason, the development of more effective therapeutic approaches for GBM is of critical importance. Low tumor oxygenation, also known as hypoxia, constitutes a major concern for GBM patients, since it promotes cancer cell spreading (invasion) into the healthy brain tissue in order to evade this adverse microenvironment. Tumor invasion not only constitutes a major obstacle to surgery, radiotherapy, and chemotherapy, but it is also the main cause of death in GBM patients. Understanding how hypoxia triggers the GBM cells to become invasive is paramount to developing novel and more effective therapies against this devastating disease. In this review, we will present a comprehensive examination of the available literature focused on investigating how GBM hypoxia triggers an invasive cancer cell phenotype and the role of these invasive proteins in GBM progression.