Cytokine receptor CXCR4 mediates estrogen-independent tumorigenesis, metastasis, and resistance to endocrine therapy in human breast cancer

TCF12 regulates exosome release from epirubicin-treated CAFs to promote ER+ breast cancer cell chemoresistance

Cancer-associated fibroblasts (CAFs) are the predominant stromal cells in the microenvironment and play important roles in tumor progression, including chemoresistance. However, the response of CAFs to chemotherapeutics and their effects on chemotherapeutic outcomes are largely unknown. In this study, we showed that epirubicin (EPI) treatment triggered ROS which initiated autophagy in CAFs, TCF12 inhibited autophagy flux and further promoted exosome secretion. Inhibition of EPI-induced reactive oxygen species (ROS) production with N-acetyl-L-cysteine (NAC) or suppression of autophagic initiation with short interfering RNA (siRNA) against ATG5 blunted exosome release from CAFs. Furthermore, exosome secreted from EPI-treated CAFs not only prevented ROS accumulation in CAFs but also upregulated the CXCR4 and c-Myc protein levels in recipient ER+ breast cancer cells, thus promoting EPI resistance of tumor cells. Together, the current study provides novel insights into the role of stressed CAFs in promoting tumor chemoresistance and reveal a new function of TCF12 in regulating autophagy impairment and exosome release.

Potential therapeutic role for pigment epithelium-derived factor in post-menopausal breast cancer bone metastasis

OBJECTIVES

This review discusses key oestrogens associated with the circulating pre- and post-menopausal milieu and how they may impact intratumoral oestrogen levels and breast cancer (BC) metastasis. It also identifies critical steps in BC metastasis to bone from the viewpoint of pigment epithelium-derived factor (PEDF) function, and discusses the role of several associated pro-metastatic biomarkers in BC bone metastasis.

KEY FINDINGS

PEDF is regulated by oestrogen in a number of oestrogen-sensitive tissues. Changes in circulating oestrogen levels associated with menopause may enhance the growth of BC bone metastases, leading to the establishment of a pre-metastatic niche. The establishment of such a pre-metastatic niche is driven by several key mediators, with pro-osteoclastic and pro-metastatic function which are upregulated by BC cells. These mediators appear to be regulated by oestrogen, as well as differentially affected by menopausal status. PEDF interacts with several pro-metastatic, pro-osteoclastic biomarkers, including C-X-C motif chemokine receptor 4 (CXCR4) and nuclear factor kappa B (NFκB) in BC bone metastasis.

CONCLUSION

Mediators such as CXCR4 and MT1-MMP underpin the ability of PEDF to function as an antimetastatic in other cancers such as osteosarcoma, highlighting the possibility that this serpin could be used as a therapeutic against BC metastasis in future.

Recent advances in therapeutic strategies for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer (BC) with a poor prognosis. Current treatment options are limited to surgery, adjuvant chemotherapy and radiotherapy; however, a proportion of patients have missed the surgical window at the time of diagnosis. TNBC is a highly heterogeneous cancer with specific mutations and aberrant activation of signaling pathways. Hence, targeted therapies, such as those targeting DNA repair pathways, androgen receptor signaling pathways, and kinases, represent promising treatment options against TNBC. In addition, immunotherapy has also been demonstrated to improve overall survival and response in TNBC. In this review, we summarize recent key advances in therapeutic strategies based on molecular subtypes in TNBC.

Clinical Evaluation of Nuclear Imaging Agents in Breast Cancer

Precision medicine is the customization of therapy for specific groups of patients using genetic or molecular profiling. Noninvasive imaging is one strategy for molecular profiling and is the focus of this review. The combination of imaging and therapy for precision medicine gave rise to the field of theranostics. In breast cancer, the detection and quantification of therapeutic targets can help assess their heterogeneity, especially in metastatic disease, and may help guide clinical decisions for targeted treatments. Positron emission tomography (PET) or single-photon emission tomography (SPECT) imaging has the potential to play an important role in the molecular profiling of therapeutic targets in vivo for the selection of patients who are likely to respond to corresponding targeted therapy. In this review, we discuss the state-of-the-art nuclear imaging agents in clinical research for breast cancer. We reviewed 17 clinical studies on PET or SPECT agents that target 10 different receptors in breast cancer. We also discuss the limitations of the study designs and of the imaging agents in these studies. Finally, we offer our perspective on which imaging agents have the highest potential to be used in clinical practice in the future.

Obesity and endocrine therapy resistance in breast cancer: Mechanistic insights and perspectives

The incidence of obesity, a recognized risk factor for various metabolic and chronic diseases, including numerous types of cancers, has risen dramatically over the recent decades worldwide. To date, convincing research in this area has painted a complex picture about the adverse impact of high body adiposity on breast cancer onset and progression. However, an emerging but overlooked issue of clinical significance is the limited efficacy of the conventional endocrine therapies with selective estrogen receptor modulators (SERMs) or degraders (SERDs) and aromatase inhibitors (AIs) in patients affected by breast cancer and obesity. The mechanisms behind the interplay between obesity and endocrine therapy resistance are likely to be multifactorial. Therefore, what have we actually learned during these years and which are the main challenges in the field? In this review, we will critically discuss the epidemiological evidence linking obesity to endocrine therapeutic responses and we will outline the molecular players involved in this harmful connection. Given the escalating global epidemic of obesity, advances in understanding this critical node will offer new precision medicine-based therapeutic interventions and more appropriate dosing schedule for treating patients affected by obesity and with breast tumors resistant to endocrine therapies.

NEK5 activity regulates the mesenchymal and migratory phenotype in breast cancer cells

PURPOSE

Breast cancer remains a prominent global disease affecting women worldwide despite the emergence of novel therapeutic regimens. Metastasis is responsible for most cancer-related deaths, and acquisition of a mesenchymal and migratory cancer cell phenotypes contributes to this devastating disease. The utilization of kinase targets in drug discovery have revolutionized the field of cancer research but despite impressive advancements in kinase-targeting drugs, a large portion of the human kinome remains understudied in cancer. NEK5, a member of the Never-in-mitosis kinase family, is an example of such an understudied kinase. Here, we characterized the function of NEK5 in breast cancer.

METHODS

Stably overexpressing NEK5 cell lines (MCF7) and shRNA knockdown cell lines (MDA-MB-231, TU-BcX-4IC) were utilized. Cell morphology changes were evaluated using immunofluorescence and quantification of cytoskeletal components. Cell proliferation was assessed by Ki-67 staining and transwell migration assays tested cell migration capabilities. In vivo experiments with murine models were necessary to demonstrate NEK5 function in breast cancer tumor growth and metastasis.

RESULTS

NEK5 activation altered breast cancer cell morphology and promoted cell migration independent of effects on cell proliferation. NEK5 overexpression or knockdown does not alter tumor growth kinetics but promotes or suppresses metastatic potential in a cell type-specific manner, respectively.

CONCLUSION

While NEK5 activity modulated cytoskeletal changes and cell motility, NEK5 activity affected cell seeding capabilities but not metastatic colonization or proliferation in vivo. Here we characterized NEK5 function in breast cancer systems and we implicate NEK5 in regulating specific steps of metastatic progression.

Utilizing the Hippo pathway as a therapeutic target for combating endocrine-resistant breast cancer

Drug resistance is always a great obstacle in any endocrine therapy of breast cancer. Although the combination of endocrine therapy and targeted therapy has been shown to significantly improve prognosis, refractory endocrine resistance is still common. Dysregulation of the Hippo pathway is often related to the occurrence and the development of many tumors. Targeted therapies of this pathway have played important roles in the study of triple negative breast cancer (TNBC). Targeting the Hippo pathway in combination with chemotherapy or other targeted therapies has been shown to significantly improve specific antitumor effects and reduce cancer antidrug resistance. Further exploration has shown that the Hippo pathway is closely related to endocrine resistance, and it plays a "co-correlation point" role in numerous pathways involving endocrine resistance, including related pathways in breast cancer stem cells (BCSCs). Agents and miRNAs targeting the components of the Hippo pathway are expected to significantly enhance the sensitivity of breast cancer cells to endocrine therapy. This review initially explains the possible mechanism of the Hippo pathway in combating endocrine resistance, and it concludes by recommending endocrine therapy in combination with therapies targeting the Hippo pathway in the study of endocrine-resistant breast cancers.

At the Bench: Pre-clinical evidence for multiple functions of CXCR4 in cancer

Signaling through chemokine receptor, C-X-C chemokine receptor type 4 (CXCR4) regulates essential processes in normal physiology, including embryogenesis, tissue repair, angiogenesis, and trafficking of immune cells. Tumors co-opt many of these fundamental processes to directly stimulate proliferation, invasion, and metastasis of cancer cells. CXCR4 signaling contributes to critical functions of stromal cells in cancer, including angiogenesis and multiple cell types in the tumor immune environment. Studies in animal models of several different types of cancers consistently demonstrate essential functions of CXCR4 in tumor initiation, local invasion, and metastasis to lymph nodes and distant organs. Data from animal models support clinical observations showing that integrated effects of CXCR4 on cancer and stromal cells correlate with metastasis and overall poor prognosis in >20 different human malignancies. Small molecules, Abs, and peptidic agents have shown anticancer efficacy in animal models, sparking ongoing efforts at clinical translation for cancer therapy. Investigators also are developing companion CXCR4-targeted imaging agents with potential to stratify patients for CXCR4-targeted therapy and monitor treatment efficacy. Here, pre-clinical studies demonstrating functions of CXCR4 in cancer are reviewed.

Application of a small molecule inhibitor screen approach to identify CXCR4 downstream signaling pathways that promote a mesenchymal and fulvestrant-resistant phenotype in breast cancer cells

Chemokine receptor 4 (CXCR4) and its ligand stromal-derived factor 1 (SDF-1) have well-characterized functions in cancer metastasis; however, the specific mechanisms through which CXCR4 promotes a metastatic and drug-resistant phenotype remain widely unknown. The aim of the present study was to demonstrate the application of a phenotypic screening approach using a small molecule inhibitor library to identify potential CXCR4-mediated signaling pathways. The present study demonstrated a new application of the Published Kinase Inhibitor Set (PKIS), a library of small molecule inhibitors from diverse chemotype series with varying levels of selectivity, in a phenotypic medium-throughput screen to identify potential mechanisms to pursue. Crystal violet staining and brightfield microscopy were employed to evaluate relative cell survival and changes to cell morphology in the screens. ‘Hits’ or lead active compounds in the first screen were PKIS inhibitors that reversed mesenchymal morphologies in CXCR4-activated breast cancer cells without the COOH-terminal domain (MCF-7-CXCR4-ΔCTD) and in the phenotypically mesenchymal triple-negative breast cancer cells (MDA-MB-231, BT-549 and MDA-MB-157), used as positive controls. In a following screen, the phenotypic and cell viability screen was used with a positive control that was both morphologically mesenchymal and had acquired fulvestrant resistance. Compounds within the same chemotype series were identified that exhibited biological activity in the screens, the ‘active’ inhibitors, were compared with inactive compounds. Relative kinase activity was obtained using published datasets to discover candidate kinase targets responsible for CXCR4 activity. MAP4K4 and MINK reversed both the mesenchymal and drug-resistant phenotypes, NEK9 and DYRK2 only reversed the mesenchymal morphology, and kinases, including ROS, LCK, HCK and LTK, altered the fulvestrant-resistant phenotype. Oligoarray experiments revealed pathways affected in CXCR4-activated cells, and these pathways were compared with the present screening approach to validate our screening tool. The oligoarray approach identified the integrin-mediated, ephrin B-related, RhoA, RAC1 and ErbB signaling pathways to be upregulated in MCF-7-CXCR4-ΔCTD cells, with ephrin B signaling also identified in the PKIS phenotypic screen. The present screening tool may be used to discover potential mechanisms of targeted signaling pathways in solid cancers.

Addressing the tumour microenvironment in early drug discovery: a strategy to overcome drug resistance and identify novel targets for cancer therapy

The tumour microenvironment (TME) comprises not only malignant and non-malignant cells, but also the extracellular matrix (ECM), secreted factors, and regulators of cellular functions. In addition to genetic alterations, changes of the biochemical/biophysical properties or cellular composition of the TME have been implicated in drug resistance. Here, we review the composition of the ECM and different elements of the TME contributing to drug resistance, including soluble factors, hypoxia, extracellular acidity, and cell adhesion properties. We discuss selected approaches for modelling the TME, current progress, and their use in low-and high-throughput assays for preclinical studies. Lastly, we summarise the status quo of advanced 3D cancer models compatible with high-throughput screening (HTS), the technical practicalities and challenges.

The Signaling Duo CXCL12 and CXCR4: Chemokine Fuel for Breast Cancer Tumorigenesis

Simple Summary

Breast cancer remains the most common malignancy in women. In this review, we explore the role of the CXCL12/CXCR4 pathway in breast cancer. We show that the CXCL12/CXCR4 cascade is involved in nearly every aspect of breast cancer tumorigenesis including proliferation, cell motility and distant metastasis. Moreover, we summarize current knowledge about the CXCL12/CXCR4-targeted therapies. Due to the critical roles of this pathway in breast cancer and other malignancies, we believe that audiences in different fields will find this overview helpful.

Abstract

The CXCL12/CXCR4 signaling pathway has emerged in the recent years as a key player in breast cancer tumorigenesis. This pathway controls many aspects of breast cancer development including cancer cell proliferation, motility and metastasis to all target organs. Moreover, the CXCL12/CXCR4 cascade affects both immune and stromal cells, creating tumor-supporting microenvironment. In this review, we examine state-of-the-art knowledge about detrimental roles of the CXCL12/CXCR4 signaling, discuss its therapeutic potential and suggest further research directions beneficial both for basic research and personalized medicine in breast cancer.

Role of the CXCR4-LASP1 Axis in the Stabilization of Snail1 in Triple-Negative Breast Cancer

The CXCL12-CXCR4 axis plays a vital role in many steps of breast cancer metastasis, but the molecular mechanisms have not been fully elucidated. We previously reported that activation of CXCR4 by CXCL12 promotes the nuclear localization of LASP1 (LIM and SH3 protein 1). The nuclear LASP1 then interacts with Snail1 in triple-negative breast cancer (TNBC) cell lines. In this study, we report that the nuclear accumulation and retention of Snail1 was dependent on an increase in nuclear LASP1 levels driven by active CXCR4. The CXCR4-LASP1 axis may directly regulate the stabilization of nuclear Snail1, by upregulating nuclear levels of pS473-Akt, pS9-GSK-3β, A20, and LSD1. Furthermore, the activation of CXCR4 induced association of LASP1 with Snail1, A20, GSK-3β, and LSD1 endogenously. Thus, nuclear LASP1 may also regulate protein-protein interactions that facilitate the stability of Snail1. Genetic ablation of LASP1 resulted in the mislocalization of nuclear Snail1, loss of the ability of TNBC cells to invade Matrigel and a dysregulated expression of both epithelial and mesenchymal markers, including an increased expression of ALDH1A1, a marker for epithelial breast cancer stem-like cells. Our findings reveal a novel role for the CXCR4-LASP1 axis in facilitating the stability of nuclear localized Snail1.

RelB sustains endocrine resistant malignancy: an insight of noncanonical NF-κB pathway into breast Cancer progression

BACKGROUND

The activation of the NF-κB pathway plays a crucial role in the progression of breast cancer (BCa) and also involved in endocrine therapy resistance. On the contrary to the canonical NF-κB pathway, the effect of the noncanonical NF-κB pathway in BCa progression remains elusive.

METHODS

BCa tumor tissues and the corresponding cell lines were examined to determine the correlation between RelB and the aggressiveness of BCa. RelB was manipulated in BCa cells to examine whether RelB promotes cell proliferation and motility by quantitation of apoptosis, cell cycle, migration, and invasion. RNA-Seq was performed to identify the critical RelB-regulated genes involved in BCa metastasis. Particularly, RelB-regulated MMP1 transcription was verified using luciferase reporter and ChIP assay. Subsequently, the effect of RelB on BCa progression was further validated using BCa mice xenograft models.

RESULTS

RelB uniquely expresses at a high level in aggressive BCa tissues, particularly in triple-negative breast cancer (TNBC). RelB promotes BCa cell proliferation through increasing G1/S transition and/or decreasing apoptosis by upregulation of Cyclin D1 and Bcl-2. Additionally, RelB enhances cell mobility by activating EMT. Importantly, RelB upregulates bone metastatic protein MMP1 expression through binding to an NF-κB enhancer element located at the 5'-flanking region. Accordingly, in vivo functional validation confirmed that RelB deficiency impairs tumor growth in nude mice and inhibits lung metastasis in SCID mice. Video abstract.

Prognostic Value of CXCR2 in Breast Cancer

The tumor microenvironment appears essential in cancer progression and chemokines are mediators of the communication between cancer cells and stromal cells. We have previously shown that the ligands of the chemokine receptor CXCR2 were expressed at higher levels in triple-negative breast cancers (TNBC). Our hypothesis was that CXCR2 expression could also be altered in breast cancer. Here, we have analyzed the potential role of CXCR2 in breast cancer in a retrospective cohort of 105 breast cancer patients. Expression of CXCR2, CD11b (a marker of granulocytes) and CD66b (a marker of neutrophils) was analyzed by immunohistochemistry on tumor samples. We demonstrated that CXCR2 stained mainly stromal cells and in particular neutrophils. CXCR2, CD11b and CD66b expression were correlated with high grade breast cancers. Moreover, TNBC displayed a higher expression of CXCR2, CD11b and CD66b than hormone receptor positive or Her2 positive tumors. High levels of CXCR2 and CD11b, but not CD66b, were associated with a higher infiltration of T lymphocytes and B lymphocytes. We also observed a correlation between CXCR2 and AP-1 activity. In univariate analyses, CXCR2, but not CD11b or CD66b, was associated with a lower risk of relapse; CXCR2 remained significant in multivariate analysis. Our data suggest that CXCR2 is a stromal marker of TNBC. However, higher levels of CXCR2 predicted a lower risk of relapse.

CXCR4 Antagonist AMD3100 Reverses the Resistance to Tamoxifen in Breast Cancer via Inhibiting AKT Phosphorylation

Endocrine therapy is a systemic therapy and has become the main treatment strategy for patients with estrogen receptor (ER)-positive breast cancer. However, tamoxifen resistance has become an insurmountable clinical challenge, and the underlying mechanisms are still poorly understood. In this study, we explored the roles of CXC chemokine receptor type 4 (CXCR4) in tamoxifen-treated breast cancer and tamoxifen resistance. Based on the Gene Expression Omnibus (GEO) database, high expression of CXCR4 was found to be associated with worse overall survival (hazard ratio [HR] = 4.646, p < 0.001) and cancer-specific survival (HR = 4.480, p < 0.001) in tamoxifen-treated breast cancer. CXCR4 was also positively correlated with the level of AKT phosphorylation and the resistance to tamoxifen in breast cancer. AMD3100 is a CXCR4 antagonist and was found to decrease phosphorylated (p)-AKT levels of tamoxifen-resistant cells. The reversal effect of AMD3100 on tamoxifen resistance was also confirmed in vitro and in vivo. Taken together, our study demonstrated that CXCR4 could be a potential prognostic biomarker for tamoxifen-treated breast cancer, and the combination of AMD3100 with tamoxifen could be a more efficacious therapeutic strategy for the treatment of tamoxifen resistance.

Beyond Cell Motility: The Expanding Roles of Chemokines and Their Receptors in Malignancy

The anti-tumor activities of some members of the chemokine family are often overcome by the functions of many chemokines that are strongly and causatively linked with increased tumor progression. Being key leukocyte attractants, chemokines promote the presence of inflammatory pro-tumor myeloid cells and immune-suppressive cells in tumors and metastases. In parallel, chemokines elevate additional pro-cancerous processes that depend on cell motility: endothelial cell migration (angiogenesis), recruitment of mesenchymal stem cells (MSCs) and site-specific metastasis. However, the array of chemokine activities in cancer expands beyond such “typical” migration-related processes and includes chemokine-induced/mediated atypical functions that do not activate directly motility processes; these non-conventional chemokine functions provide the tumor cells with new sets of detrimental tools. Within this scope, this review article addresses the roles of chemokines and their receptors at atypical levels that are exerted on the cancer cell themselves: promoting tumor cell proliferation and survival; controlling tumor cell senescence; enriching tumors with cancer stem cells; inducing metastasis-related functions such as epithelial-to-mesenchymal transition (EMT) and elevated expression of matrix metalloproteinases (MMPs); and promoting resistance to chemotherapy and to endocrine therapy. The review also describes atypical effects of chemokines at the tumor microenvironment: their ability to up-regulate/stabilize the expression of inhibitory immune checkpoints and to reduce the efficacy of their blockade; to induce bone remodeling and elevate osteoclastogenesis/bone resorption; and to mediate tumor-stromal interactions that promote cancer progression. To illustrate this expanding array of atypical chemokine activities at the cancer setting, the review focuses on major metastasis-promoting inflammatory chemokines—including CXCL8 (IL-8), CCL2 (MCP-1), and CCL5 (RANTES)—and their receptors. In addition, non-conventional activities of CXCL12 which is a key regulator of tumor progression, and its CXCR4 receptor are described, alongside with the other CXCL12-binding receptor CXCR7 (RDC1). CXCR7, a member of the subgroup of atypical chemokine receptors (ACKRs) known also as ACKR3, opens the gate for discussion of atypical activities of additional ACKRs in cancer: ACKR1 (DARC, Duffy), ACKR2 (D6), and ACKR4 (CCRL1). The mechanisms involved in chemokine activities and the signals delivered by their receptors are described, and the clinical implications of these findings are discussed.

Endocrinotherapy resistance of prostate and breast cancer: Importance of the NF‑κB pathway (Review)

Prostate cancer (PCa) and breast cancer (BCa) are two common sex hormone‑related cancer types with high rates of morbidity, and are leading causes of cancer death globally in men and women, respectively. The biological function of androgen or estrogen is a key factor for PCa or BCa tumorigenesis, respectively. Nevertheless, after hormone deprivation therapy, the majority of patients ultimately develop hormone‑independent malignancies that are resistant to endocrinotherapy. It is widely recognized, therefore, that understanding of the mechanisms underlying the process from hormone dependence towards hormone independence is critical to discover molecular targets for the control of advanced PCa and BCa. This review aimed to dissect the important mechanisms involved in the therapeutic resistance of PCa and BCa. It was concluded that activation of the NF‑κB pathway is an important common mechanism for metastasis and therapeutic resistance of the two types of cancer; in particular, the RelB‑activated noncanonical NF‑κB pathway appears to be able to lengthen and strengthen NF‑κB activity, which has been a focus of recent investigations.

Increased Survival by Pulmonary Treatment of Established Lung Metastases with Dual STAT3/CXCR4 Inhibition by siRNA Nanoemulsions

Lung metastasis is a common and deadly occurrence in many types of solid tumors. Chemokine receptor CXCR4 and transcription factor signal transducer and activator of transcription 3 (STAT3) are among potential therapeutic targets in lung metastatic cancer. Both CXCR4 and STAT3 play important roles in the proliferation, angiogenesis, and metastasis of cancer cells. Here, we report on the development of a pulmonary delivery (p.d.) system based on perfluorocarbon (PFC) nanoemulsions for combined delivery of a partially fluorinated polymeric CXCR4 antagonist (FM) and anti-STAT3 small interfering RNA (siRNA). We have prepared FM-stabilized PFC (FM@PFC) as a delivery system of therapeutic siRNA adsorbed on the surface of the emulsion. These FM@PFC/siRNA nanoemulsions inhibited both CXCR4 and STAT3, as demonstrated by effective anti-invasive ability in vitro and related antimetastatic activity in vivo. The combined nanoemulsions provided a comprehensive anticancer effect in the model of established lung metastasis of breast carcinoma, which was dependent on induction of cancer cell apoptosis, anti-angiogenic effect, anti-invasive activity, and overcoming of the immunosuppressive tumor microenvironment. Direct comparison with intravenous (i.v.) injection showed superior activity of pulmonary administration as indicated by significantly increased animal survival. Overall, this work established the suitability of the PFC nanoemulsions for p.d. of combination anticancer treatments and as a promising method to treat lung metastasis.

CXCR4 and CXCR3 are two distinct prognostic biomarkers in breast cancer: Database mining for CXCR family members

CXC chemokine receptors (CXCRs) and chemokines are involved in tissue development and homeostasis, including in cancer development and progression. To date, seven CXCRs have been identified. However, the expression of CXCRs and their influence on the occurrence and development of breast cancer (BC) requires further investigation. In the present study, mRNA expression levels of the seven CXCRs were compared between normal tissues and several cancer types using the Oncomine database. Highly expressed CXCRs were selected and the expression levels of these CXCRs were examined in different subtypes of BC using the Gene Expression-Based Outcome for Breast Cancer database. Finally, the prognostic value of these CXCRs was examined using Kaplan-Meier plotter. It was found that, compared with normal controls, transcripts of CXCR4 and CXCR3 were significantly overexpressed in BC samples compared with other CXCRs. Survival analysis showed that high expression of CXCR4 promoted the recurrence of BC but had no impact on overall survival (OS), while a high level of CXCR3 transcript expression was significantly associated with increased survival in patients with BC. With regards to different subtypes of BC, the present study revealed that high CXCR4 transcript expression was significantly associated with both longer relapse-free survival and OS only in basal-like BC. Furthermore, CXCR4 promoted chemosensitivity in patients with basal-like BC and induced resistance against endocrine therapy for patients with luminal A BC. Thus, CXCR4 and CXCR3 are two distinct prognostic biomarkers and further studies are required.

Recent Advances in Nuclear Imaging of Receptor Expression to Guide Targeted Therapies in Breast Cancer

Breast cancer remains the most frequent cancer in women with different patterns of disease progression and response to treatments. The identification of specific biomarkers for different breast cancer subtypes has allowed the development of novel targeting agents for imaging and therapy. To date, patient management depends on immunohistochemistry analysis of receptor status on bioptic samples. This approach is too invasive, and in some cases, not entirely representative of the disease. Nuclear imaging using receptor tracers may provide whole-body information and detect any changes of receptor expression during disease progression. Therefore, imaging is useful to guide clinicians to select the best treatments for each patient and to evaluate early response thus reducing unnecessary therapies. In this review, we focused on the development of novel tracers that are ongoing in preclinical and/or clinical studies as promising tools to lead treatment decisions for breast cancer management.

CXCR4 mutations affect presentation and outcomes in patients with Waldenström macroglobulinemia: A systematic review

Introduction: The genomic landscape of Waldenström macroglobulinemia (WM) is characterized by recurrent MYD88 (MYD88^L265P) and CXCR4 mutations (CXCR4^MUT), detected in 90% and 30% of cases, respectively. The role of CXCR4^MUT in clinical features and outcomes to therapy in WM patients is evolving. Areas covered: We performed a systematic review aimed at evaluating the prevalence of CXCR4^MUT in WM patients, and at assessing differences in clinical features and outcomes to therapy between WM patients with and without CXCR4^MUT. Seventeen studies were included in our analysis. The pooled prevalence of CXCR4^MUT in WM patients was 31%; 34% in MYD88^L265P and 5% in MYD88^WT patients. CXCR4^MUT were associated with higher serum IgM levels and higher risk of hyperviscosity than CXCR4^WT patients. Very good partial response (VGPR) and progression-free survival (PFS) rates to ibrutinib, with and without rituximab, appeared lower in CXCR4^MUT than in CXCR4^WT patients. Response and PFS rates were not affected by CXCR4^MUT status on patients treated with proteasome inhibitors. Expert opinion: Our systematic review shows that WM patients with CXCR4^MUT have specific clinical features and have lower response and PFS rates to BTK inhibitors. Our findings support standardization of CXCR4 testing and development of CXCR4-directed therapy.

CXCR4 antagonism in combination with IDO1 inhibition weakens immune suppression and inhibits tumor growth in mouse breast cancer bone metastases

Purpose

To investigate whether inhibition of the CXCL12/CXCR4 axis or IDO1 could produce antitumor effects in a metastasized breast cancer immunocompetent animal model.

Methods

Breast cancer metastasis models were established in mice. CXCR4 inhibitor and IDO1 inhibitor were used to evaluate the anticancer effects.

Results

Combination treatment using the CXCR4 antagonist AMD3465 and the IDO1 inhibitor D1MT successfully delayed the progression of breast cancer bone metastases. AMD3465 reduced the number of intratumoral regulatory T-cells (Tregs) and myeloid-derived suppressor cells (MDSCs), while D1MT facilitated the antitumor effects of intratumoral CD8+ T-cells. IDO1 inhibition elevated the expression of perforin, granzyme-B, and IFN-γ in CD8+ T-cells, and AMD3465 treatment weakened the potential immune suppressive effects of Tregs and MDSCs. As a result, combination treatment significantly prolonged tumor-bearing mouse survival in two metastasis models, and these antitumor effects relied on overexpression of indoleamine 2, 3-dioxygenase 1 (IDO1), an enzyme that modulates the immune response and impairs immune attack in ovarian cancers CXCR3+ CD8+ cytotoxic T-cell function.

Conclusion

The current study provides preclinical evidence that AMD3465 treatment in combination with IDO1 inhibition may be a promising therapeutic regimen for refractory metastasized breast cancers.

Examination of methylation changes of VIM, CXCR4, DOK7, and SPDEF genes in peripheral blood DNA in breast cancer patients

BACKGROUND

Studying whole blood DNA methylation as a risk marker has valuable applications in either diagnosis or staging of breast cancer. We investigated whole blood DNA methylation status of VIM, CXCR4, DOK7, and SPDEF genes in breast cancer patients in comparison to healthy control subjects.

MATERIALS AND METHODS

60 patients with breast cancer and 40 healthy controls were examined. Genomic DNA isolated from peripheral blood and restriction enzyme polymerase chain reaction (REP) method was applied for analysis. Real-time PCR was used to confirm methylation status of the aforementioned genes and therefore to find out the methylation differences between normal and breast cancer subjects.

RESULTS

Level of DOK7 promoter hypomethylation in normal and breast cancer samples was significant (P-value = 0.001). The study, also, showed that hypomethylation of VIM and CXCR4 genes are significant in patients compared with normal cases (P-value < 0.05). Furthermore, SPDEF promoter hypomethylation was not significantly differed between normal and breast cancer samples (P-value = 0.2).

CONCLUSIONS

Hypermethylation of DOK7 gene in DNA from patients affected with breast cancer offers a biomarker for diagnosis of the breast cancer. This study indicates that methylation status of VIM and CXCR4 genes changes in breast cancer; so, they can be used as molecular biomarkers in breast cancer prognosis.

Involvement of CXCR4 in Normal and Abnormal Development

CXC motif chemokine receptor type 4 (CXCR4) is associated with normal and abnormal development, including oncogenesis. The ligand of CXCR4 is stromal cell-derived factor (SDF), also known as CXC motif ligand (CXCL) 12. Through the SDF-1/CXCR4 axis, both homing and migration of hematopoietic (stem) cells are regulated through niches in the bone marrow. Outside of the bone marrow, however, SDF-1 can recruit CXCR4-positive cells from the bone marrow. SDF/CXCR4 has been implicated in the maintenance and/or differentiation of stemness, and tissue-derived stem cells can be associated with SDF-1 and CXCR4 activity. CXCR4 plays a role in multiple pathways involved in carcinogenesis and other pathologies. Here, we summarize reports detailing the functions of CXCR4. We address the molecular signature of CXCR4 and how this molecule and cells expressing it are involved in either normal (maintaining stemness or inducing differentiation) or abnormal (developing cancer and other pathologies) events. As a constituent of stem cells, the SDF-1/CXCR4 axis influences downstream signal transduction and the cell microenvironment.

Nuclear Respiratory Factor 1 Acting as an Oncoprotein Drives Estrogen-Induced Breast Carcinogenesis

We have previously shown nuclear respiratory factor 1 (NRF1)-mediated transcriptional programming of mitobiogenesis contributes to estrogen-induced breast cancer through modulating cell cycle progression. In this study, we report a new role of NRF1 that goes beyond that of programming mitobiogenesis. Specifically, we report a novel oncogenic function of NRF1 supporting its causative role in breast cancer development and progression. The gain of NRF1 and/or treatment with 17β-estradiol (E2) produced heterogeneous breast cancer stem cell (BCSC)-like subsets composed of more than 10 distinct cell sub-populations. Flow sorting combined with confocal imaging of markers for pluripotency, epithelial mesenchymal transition (EMT), and BCSCs phenotypically confirmed that the BCSC-like subset arise from cell re-programming. Thus, we determined the molecular actions of NRF1 on its target gene CXCR4 because of its known role in the acquisition of the BCSC-like subset through EMT. CXCR4 was activated by NRF1 in a redox-dependent manner during malignant transformation. An NRF1-induced BCSC-like subset was able to form xenograft tumors in vivo, while inhibiting transcription of CXCR4 prevented xenograft tumor growth. Consistent with our observation of NRF1-driven breast tumorigenesis in the experimental model, higher protein levels of NRF1 were also found in human breast cancer tissue specimens. This highly novel role of NRF1 in the stochastic acquisition of BCSC-like subsets and their progression to a malignant phenotype may open an entirely new research direction targeting NRF1 signaling in invasive breast cancer. Our discovery of targeting transcriptional activation of CXCR4 to inhibit NRF1-induced oncogenic transformation provides a mechanistic explanation for estrogen-dependent breast carcinogenesis and opens new avenues in strategic therapeutics to fight breast cancer.

PET imaging of chemokine receptor CXCR4 in patients with primary and recurrent breast carcinoma

Background

CXCR4 is a chemokine receptor frequently overexpressed in invasive breast cancer that has been shown to play a major role in signaling pathways involved in metastasis. The aim of this retrospective analysis was to assess the diagnostic performance of CXCR4-directed PET imaging in patients with breast cancer using the recently introduced CXCR4-targeted PET probe ⁶⁸Ga-Pentixafor.

Results

Thirteen patients with first diagnosis of breast cancer, four patients with recurrent disease after primary breast cancer, and one patient with axillary lymph node metastasis of unknown primary underwent CXCR4-targeted PET imaging using ⁶⁸Ga-Pentixafor. Maximum standardized uptake values (SUVmax) and tumor-to-background (T/B) ratios of tumor lesions were measured and compared with pathological prognostic factors and molecular subtypes. ¹⁸F-FDG PET/CT images were available in 8/18 cases and were compared semi-quantitatively. Comparison with CXCR4 expression determined by immunohistochemistry was performed in 7/18 patients.

Nine of 13 primary breast cancers were visually detectable on ⁶⁸Ga-Pentixafor PET images (mean SUVmax of 3.0). The visually undetectable lesions included both cases of invasive lobular carcinoma (ILC) and two cases of invasive carcinoma of no special type (NST) without any hormone receptor and HER2 expression (triple negative). Metastases of recurrent breast cancer and unknown primary cancer were visually detectable in all five cases, exhibiting a mean SUVmax of 3.5. ¹⁸F-FDG PET demonstrated higher SUVmax in all patients compared to ⁶⁸Ga-Pentixafor PET. A correlation between SUVmax obtained from ⁶⁸Ga-Pentixafor PET and prognostic factors including estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) status, proliferation index, tumor grade, or molecular subtypes was not observed.

Conclusions

CXCR4-directed PET imaging in patients with primary and recurrent breast cancer is feasible; however, tumor detectability is significantly lower compared to ¹⁸F-FDG PET. Moreover, we did not find any correlation between aforementioned prognostic factors of breast cancer and CXCR4-targeted tracer accumulation. Based on these results in a small patient cohort, CXCR4-targeted PET imaging does not seem to be suitable as a general diagnostic tool for imaging of breast cancer. Future CXCR4 imaging studies should investigate whether this modality might be useful in more specific applications, e.g., in therapeutic approaches especially under the view of current developments in targeted immune cell and immune checkpoint inhibitory therapy.

Plasma Chemokine CCL2 and Its Receptor CCR2 Concentrations as Diagnostic Biomarkers for Breast Cancer Patients

The aim of this study was to investigate plasma levels and applicability of CCL2, CCR2, and tumor marker CA 15-3 in breast cancer (BC) patients and in relation to the control groups: patients with benign breast tumor and healthy subjects. Plasma levels of tested parameters were determined by enzyme-linked immunosorbent assay (ELISA) and CA 15-3 by Chemiluminescent Microparticle Immunoassay (CMIA). The median levels of CCL2 in entire group of BC were significantly higher compared to the control groups, similarly as median levels of CA 15-3. CCR2 is a negative marker whose levels were significantly lower in BC group compared to healthy women. The concentration of CCL2 in BC increases with advancing tumor stage, while a median level of CCR2 decreases with advancing stage. CCL2 showed the highest value of sensitivity (SE) (64.95%) in entire BC group and also in early stages of disease. The highest specificity (SP) was obtained by CA 15-3 (85.71%). The area under the ROC curve (AUC) of CCR2 (0.7304) was the largest of all the tested parameters (slightly lower than CA 15-3) in the entire BC group, but a maximum range was obtained for the combination of all tested parameters with CA 15-3 (0.8271). In early stages of BC the highest AUC of all tested parameters was observed in CCL2 or CCR2 (stage I: 0.6604 and 0.6564; respectively; stage II: 0.7768, respectively, for CCR2). The findings of this study suggest that there may be applicability of CCL2, CCR2 in diagnosis of BC patients, particularly in conjunction with CA 15-3.

Bioinformatic analyses reveal the key pathways and genes in the CXCR4 mediated mesenchymal subtype of glioblastoma

Glioblastoma multiforme (GBM) is one of the most lethal types of tumour, despite severe treatment methods. The Cancer Genome Atlas has categorised GBMs into proneural, neural, classical and mesenchymal subtypes; the mesenchymal subgroup has the worst prognosis. CXCR4 has been reported as selectively overexpressed in the mesenchymal subtype and positively associated with MES markers. However, to the best of our knowledge the underlying mechanisms regarding how CXCR4 may regulate mesenchymal GBM are still unknown. The present study aimed to investigate the critical pathways mediated by CXCR4 in mesenchymal GBM using bioinformatic analyses. The results suggested that CXCR4 is a predictor of poor prognosis and may serve as a biomarker of the mesenchymal subtype in patients with GBM. In addition, CXCR4 mediated the mitogen‑activated protein kinase signaling pathway, which was identified specifically in patients with mesenchymal GBM. CXCR4 associated genes or pathways may be a 'basket trial' option for the management of melanoma, prostate cancer and mesenchymal GBM.

Promise of chemokine network-targeted nanoparticles in combination nucleic acid therapies of metastatic cancer

Chemokines and chemokine receptors play key roles in cancer progression and metastasis. Although multiple chemokines and chemokine receptors have been investigated, inhibition of CXCR4 emerged as one of the most promising approaches in combination cancer therapy, especially when focused on the metastatic disease. Small RNA molecules, such as small interfering RNA (siRNA) and microRNA (miRNA), represent new class of therapeutics for cancer treatment through RNA interference-mediated gene silencing. However, the clinical applicability of siRNA and miRNA is severely limited by the lack of effective delivery systems. There is a significant therapeutic potential for CXCR4-targeted nanomedicines in combination with the delivery of siRNA and miRNA in cancer. Recently developed CXCR4-targeted polymeric drugs and nanomedicines, including cyclam- and chloroquine-based polymeric CXCR4 antagonists are introduced here and their ability to deliver functional siRNA and miRNA is discussed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

CXCR4/CXCL12 Signaling and Protumor Macrophages in Primary Tumors and Sentinel Lymph Nodes Are Involved in Luminal B Breast Cancer Progression

Luminal B breast cancers (BC) have a more aggressive behavior associated with a higher rate of tumor relapse and worse prognosis compared to luminal A tumors. In this study, we evaluated the involvement of specific epithelial-to-mesenchymal transition- (EMT-) and immune-related pathways in the dissemination of luminal B BC cells. The expression of 42 EMT- and immune-related genes was evaluated in matched sentinel lymph nodes (SLNs) analyzed by the one-step nucleic acid amplification assay (OSNA) and primary tumors of 40 luminal B BC patients by gene array and immunohistochemistry. The results were validated in an independent group of 150 luminal B tumors by immunohistochemistry and immunofluorescence and using gene expression data from 315 luminal B BC patients included in the Metabric dataset. We found that the expression of CXCR4 (p = 3.28E − 02) and CD163 (p = 6.92E − 03) was significantly upregulated in SLNs of recurrent luminal B BC patients. Luminal B primary tumors overexpressing CXCR4 were characterized by an increased expression of vimentin and a high content of CD163-positive macrophages. Bioinformatics analysis confirmed the correlation of CXCR4 with CXCL12, VIM, and CD163 expression and LN involvement. Our results suggest that the upregulation of the CXCR4/CXCL12 pathway and the presence of protumor macrophages in the primary tumor and SLNs sustain the aggressiveness of an important subgroup of luminal B BC.

Cytokine-mediated therapeutic resistance in breast cancer

Therapeutic resistance leading to tumor relapse is a major challenge in breast cancer (BCa) treatment. Numerous factors involved in multiple mechanisms promote the development of tumor chemo/radio-resistance. Cytokines/chemokines are important inflammatory factors and highly related to tumorigenesis, metastasis and tumors responses to treatment. A large number of studies have demonstrated that the network of cytokines activates multiple cell signaling pathways to promote tumor cell survival, proliferation, invasion, and migration. Particularly in BCa, cytokines-enhanced the epithelial-mesenchymal transition (EMT) process plays a pivotal role in the progression of metastatic phenotypes and resistance to the traditional chemo/radio-therapy. Virtually, therapeutic resistance is not entirely determined by tumor cell intrinsic characteristics but also dependent upon synchronized effects by numerous of local microenvironmental factors. Emerging evidence highlighted that exosomes secreted from various types of cells promote intercellular communication by transferring bioactive molecules including miRNAs and cytokines, suggesting that exosomes are essential for sustentation of tumor progression and therapeutic resistance within the tumor microenvironment. In this review, we discuss the mechanisms by which cytokines promote therapeutic resistance of BCa and suggest a potential approach for improving BCa therapeutics by inhibition of exosome function.

Human Cytomegalovirus UL111A and US27 Gene Products Enhance the CXCL12/CXCR4 Signaling Axis via Distinct Mechanisms

Human cytomegalovirus (HCMV) is a prevalent pathogen that establishes lifelong infection in the host. Virus persistence is aided by extensive manipulation of the host immune system, particularly cytokine and chemokine signaling pathways. The HCMV UL111A gene encodes cmvIL-10, an ortholog of human interleukin-10 that has many immunomodulatory effects. We found that cmvIL-10 increased signaling outcomes from human CXCR4, a chemokine receptor with essential roles in hematopoiesis and immune cell trafficking, in response to its natural ligand CXCL12. Calcium flux and chemotaxis to CXCL12 were significantly greater in the presence of cmvIL-10 in monocytes, epithelial cells, and fibroblasts that express CXCR4. cmvIL-10 effects on CXCL12/CXCR4 signaling required the IL-10 receptor and Stat3 activation. Heightened signaling occurred both in HCMV-infected cells and in uninfected bystander cells, suggesting that cmvIL-10 may broadly influence chemokine networks by paracrine signaling during infection. Moreover, CXCL12/CXCR4 signaling was amplified in HCMV-infected cells compared to mock-infected cells even in the absence of cmvIL-10. Enhanced CXCL12/CXCR4 outcomes were associated with expression of the virally encoded chemokine receptor US27, and CXCL12/CXCR4 activation was reduced in cells infected with a deletion mutant lacking US27 (TB40/E-mCherry-US27Δ). US27 effects were Stat3 independent but required close proximity to CXCR4 in cell membranes of either HCMV-infected or US27-transfected cells. Thus, HCMV encodes two proteins, cmvIL-10 and US27, that exhibit distinct mechanisms for enhancing CXCR4 signaling. Either individually or in combination, cmvIL-10 and US27 may enable HCMV to exquisitely manipulate CXCR4 signaling to alter host immune responses and modify cell trafficking patterns during infection.IMPORTANCE The human chemokine system plays a central role in host defense, as evidenced by the many strategies devised by viruses for manipulating it. Human cytomegalovirus (HCMV) is widespread in the human population, but infection rarely causes disease except in immunocompromised hosts. We found that two different HCMV proteins, cmvIL-10 and US27, act through distinct mechanisms to upregulate the signaling activity of a cellular chemokine receptor, CXCR4. cmvIL-10 is a secreted viral cytokine that affects CXCR4 signaling in both infected and uninfected cells, while US27 is a component of the virus particle and impacts CXCR4 activity only in infected cells. Both cmvIL-10 and US27 promote increased intracellular calcium signaling and cell migration in response to chemokine CXCL12 binding to CXCR4. Our results demonstrate that HCMV exerts fine control over the CXCL12/CXCR4 pathway, which could lead to enhanced virus dissemination, altered immune cell trafficking, and serious health implications for HCMV patients.

Interleukin 7-expressing fibroblasts promote breast cancer growth through sustenance of tumor cell stemness

The tumor microenvironment harbors cancer-associated fibroblasts that function as major modulators of cancer progression. Here, we assessed to which extent distinct cancer-associated fibroblast subsets impact mammary carcinoma growth and cancer cell stemness in an orthotopic murine model. We found that fibroblasts expressing the Cre recombinase under the control of the interleukin 7 promoter occupied mainly the tumor margin where they physically interacted with tumor cells. Intratumoral ablation of interleukin 7-expressing fibroblasts impaired breast tumor growth and reduced the clonogenic potential of cancer cells. Moreover, cDNA expression profiling revealed a distinct oncogenic signature of interleukin 7-producing fibroblasts. In particular, Cxcl12 expression was strongly enhanced in interleukin 7-producing fibroblasts and cell type-specific genetic ablation and systemic pharmacological inhibition revealed that the CXCL12/CXCR4 axis impacts breast tumor cell stemness. Elevated expression of CXCL12 and other stem cell factors in primary human breast cancer-associated fibroblasts indicates that certain fibroblast populations support tumor cell stemness and thereby promote breast cancer growth.

A fully human CXCR4 antibody demonstrates diagnostic utility and therapeutic efficacy in solid tumor xenografts

For physiologically important cancer therapeutic targets, use of non-invasive imaging for therapeutic guidance and monitoring may improve outcomes for treated patients. The CXC chemokine receptor 4 (CXCR4) is overexpressed in many cancers including non-small cell lung cancer (NSCLC) and triple negative breast cancer (TNBC). CXCR4 overexpression contributes to tumor growth, progression and metastasis. There are several CXCR4-targeted therapeutic agents currently in clinical trials. Since CXCR4 is also crucial for normal biological functions, its prolonged inhibition could lead to unwanted toxicities. While CXCR4-targeted imaging agents and inhibitors have been reported and evaluated independently, there are currently no studies demonstrating CXCR4-targeted imaging for therapeutic guidance.

Monoclonal antibodies (mAbs) are commonly used for cancer therapy and imaging. Here, an ⁸⁹Zr-labeled human CXCR4-mAb (⁸⁹Zr-CXCR4-mAb) was evaluated for detection of CXCR4 expression with positron emission tomography (PET) while its native unmodified analogue was evaluated for therapy in relevant models of NSCLC and TNBC. In vitro and in vivo evaluation of ⁸⁹Zr-CXCR4-mAb showed enhanced uptake in NSCLC xenografts with a high expression of CXCR4. It also had the ability to detect lymph node metastases in an experimental model of metastatic TNBC. Treatment of high and low CXCR4 expressing NSCLC and TNBC xenografts with CXCR4-mAb demonstrated a therapeutic response correlating with the expression of CXCR4. Considering the key role of CXCR4 in normal biological functions, our results suggest that combination of ⁸⁹Zr-CXCR4-mAb-PET with non-radiolabeled mAb therapy may provide a precision medicine approach for selecting patients with tumors that are likely to be responsive to this treatment.

Targeting CXCR7 improves the efficacy of breast cancer patients with tamoxifen therapy

Chemokine (C-X-C motif) receptor 7 (CXCR7) has been established to be involved in breast cancer (BCa) progression. However, the role of CXCR7 in different subtype of BCa still remains unclear. Here we note that CXCR7 expression is significantly amplified in Luminal type BCa tissues as compared with Her2 and TNBC types through data-mining in TCGA datasets, and its protein level positively correlates with ERα expression by staining of human BCa tissue. Interestingly, alteration of CXCR7 expression in Luminal type BCa cells is able to modulate the expression of ERα through ubiquitination at post-translational level. Additionally, overexpression of CXCR7 in these cells greatly induces 4-OHT insensitivity in vitro and is associated with earlier recurrence in patients with tamoxifen therapy. Notably, silencing ERα expression potentially rescues the sensitivity of the above cells to 4-OHT, suggesting that elevated level of ERα is responsible for CXCR7-induced 4-OHT insensitivity in Luminal type BCa. Finally, mechanistic analyses show that the reduced BRCA1 (ubiquitin E3 ligase) and elevated OTUB1 (deubiquitinase) expression, which are regulated by CXCR7/ERK1/2 signaling pathway, are responsible for stabilizing ERα protein. In conclusion, our results suggest that targeting CXCR7 may serve as a potential therapeutic strategy for improving the efficacy of BCa patients with tamoxifen therapy.

Early changes in the apparent diffusion coefficient and MMP-9 expression of a cervical carcinoma U14 allograft model following irradiation

A cervical carcinoma allograft model was designed to assess the correlation between early changes in the apparent diffusion coefficient (ADC) values on diffusion-weighted magnetic resonance imaging (DW-MRI) and the expression of matrix metalloproteinase-9 (MMP-9) in tumors. BALB/c mice with U14 tumor allografts on the right rear flank were irradiated with a single 20 Gy dose. All tumor-bearing mice were subjected to DW-MRI, followed by calculation of the ADC values and characterization of the T1 and T2 relaxation time constants. Pre- and post-irradiation ADC values were compared with the tumor volume, and the immunohistochemical staining of MMP-9 and hematoxylin-eosin (HE) staining of tumor allografts. However, no correlations between the pre-treatment ADC values and changes in tumor volumes following irradiation were observed. Notably, the mean ADC value was significantly higher in the irradiated tumors (0.756±0.102×10^-3 mm²/sec) as compared with those in the untreated tumors (0.501±0.052×10^-3 mm²/sec; P=0.002; r=0.682). Additionally, immunohistochemical staining demonstrated that MMP-9 expression in the irradiated tumors was significantly increased. The mean ADC value was significantly higher in the irradiated tumors with high MMP-9 expression levels (0.815±0.112×10^-3 mm²/sec), as compared with in the untreated tumors with low MMP-9 expression levels (0.631±0.068×10^-3 mm²/sec). Quantitative analysis determined that the ADC values were correlated with MMP-9 expression (r=0.752; P=0.003). Combined, these results suggest that radiation-induced increases in MMP-9 expression levels may be responsible for early changes in the mean ADC value and the response to irradiation in cervical carcinoma.

Association of rs1801157 single nucleotide polymorphism of CXCL12 gene in breast cancer in Pakistan and in-silico expression analysis of CXCL12-CXCR4 associated biological regulatory network

Background

C-X-C chemokine ligand 12 (CXCL12) has important implications in breast cancer (BC) pathogenesis. It is selectively expressed on B and T lymphocytes and is involved in hematopoiesis, thymocyte trafficking, stem cell motility, neovascularization, and tumorigenesis. The single nucleotide polymorphism (SNP) rs1801157 of CXCL12 gene has been found to be associated with higher risk of BC.

Methods

Our study focuses on the genotypic and allelic distribution of SNP (rs1801157; G/A) in Pakistani population as well as its association with the clinico-pathological features. The association between rs1801157 genotypes (G/A) and BC risks was assessed by a multivariate logistic regression (MLR) analysis. Genotyping was performed in both healthy individuals and patients of BC using PCR-restriction fragment length polymorphism (PCR-RFLP) method. Furthermore, in-silico approaches were adapted to investigate the association of CXCL12 and its receptor CXCR4 with genes/proteins involved in BC signalling.

Results

Significant differences in allelic and genotypic distribution between BC patients and healthy individuals of genotype (G/G) and (A/G) (p < 0.05) were observed. The frequency of the allele G in the BC group (77%) was significantly higher as compared to control group (61%) (p = 0.01). The association of genotype GG with clinico-pathological features including age, stages of cancer and organ (lung, liver, bones and brain) metastasis (p > 0.05) was assessed. In a MLR analysis, a number of variables including age, weight of an individual, affected lymph nodes, hormonal status (estrogen and progesterone receptor), alcohol consumption and family history associated with the GG genotype (GG:AA, odds ratio (OR) = 1.30, 95% CI [1.06–1.60]) were found to be independent risk factors for BC. Our in-vitro results suggest that genotype GG is possibly increasing the risk of BC in Pakistani cohorts. in-silico analysis finds that CXCL12–CXCR4 is associated with an increased expression of PDZK1, PI3k and Akt which lead the breast tumor towards metastasis.

Conclusion

Multiple targets such as CXCL12, CXCR4, PDZK1, PI3k and Akt can be inhibited in combined strategies to treat BC metastasis.

Downregulation of miR-186 is associated with metastatic recurrence of gastrointestinal stromal tumors

Although dysregulation of microRNAs (miRNAs/miRs) is a common feature of human malignancies, its involvement in gastrointestinal stromal tumors (GISTs) is not fully understood. The present study aimed to identify the miRNAs that perform a role in GIST metastasis. miRNA expression profiles from a series of 32 primary GISTs were analyzed using microarrays, and miR-186 was observed to be downregulated in tumors exhibiting metastatic recurrence. Reverse transcription-quantitative polymerase chain reaction analysis of an independent cohort of 100 primary GISTs revealed that low miR-186 expression is associated with metastatic recurrence and a poor prognosis. Inhibition of miR-186 in GIST-T1 cells promoted cell migration. Gene expression microarray analysis demonstrated that miR-186 inhibition upregulated a set of genes implicated in cancer metastasis, including insulin-like growth factor-binding protein 3, AKT serine/threonine kinase 2, hepatocyte growth factor receptor, CXC chemokine receptor 4 and epidermal growth factor-containing fibulin-like extracellular matrix protein 1. These results suggest that the downregulation of miR-186 is involved in the metastatic recurrence of GISTs, and that miR-186 levels could potentially be a predictive biomarker for clinical outcome.

CCL20 promotes migration and invasiveness of human cancerous breast epithelial cells in primary culture

The relation between the tumor and its microenvironment is one of the most interesting and less understood issues. Recently, we showed a role of CCL20 chemokine in proning the healthy tissue neighboring the tumor to carcinogenesis. Besides, tumor-secreted CCL20 induced proliferation, migration, and EMT of healthy cells. In this context, we have studied here if CCL20 had effects on the migration of cancer cells and the intracellular pathways used in breast epithelial cells in primary culture. Using molecular (siRNA) and pharmacological (inhibitors) techniques, we found multiple signaling kinases to be activated and involved in CCL20-induced tumor breast cell migration. CCL20 provoked a 2.5-fold increase of cell migration and invasion; CCL20 also enhanced MMP- 2 and MMP-9 mRNAs/protein expression and activities. Cell migration and invasiveness due to CCL20 significantly decreased when MMP-2 and MMP-9 were inhibited in CCL20-stimulated cells. CCL20 controlled MMP-2 expression through the JAK2/STAT3 pathway, while the expression of MMP-9 occurred by PKC-α that activated, consequently, c-Src, Akt, and finally NF-kB. These results reveal a role for CCL20 also in tumor breast cell and point to CCL20 as a novel therapeutic target in cancer.

UTX promotes hormonally responsive breast carcinogenesis through feed-forward transcription regulation with estrogen receptor

UTX is implicated in embryonic development and lineage specification. However, how this X-linked histone demethylase contributes to the occurrence and progression of breast cancer remains to be clarified. Here we report that UTX is physically associated with estrogen receptor (ER) and functions in ER-regulated transcription. We showed that UTX coordinates with JHDM1D and CBP to direct H3K27 methylation-acetylation transition and to create a permissive chromatin state on ER targets. Genome-wide analysis of the transcriptional targets of UTX by ChIP-seq identified a set of genes such as chemokine receptor CXCR4 that are intimately involved in breast cancer tumorigenesis and metastasis. We demonstrated that UTX promotes the proliferation and migration of ER⁺ breast cancer cells. Interestingly, UTX itself is transactivated by ER, forming a feed-forward loop in the regulation of hormone response. Indeed, UTX is upregulated during ER⁺ breast cancer progression, and the expression level of UTX is positively correlated with that of CXCR4 and negatively correlated with the overall survival of ER⁺ breast cancer patients. Our study identified a feed-forward loop between UTX and ER in the regulation of hormonally responsive breast carcinogenesis, supporting the pursuit of UTX as an emerging therapeutic target for the intervention of certain ER⁺ breast cancer with specific epigenetic vulnerability.

The role of the chemokine receptor XCR1 in breast cancer cells

Considerable attention has recently been paid to the application of chemokines to cancer immunotherapy due to their complex role in cell proliferation, invasion, metastasis, and tumorigenesis, which extends beyond the regulation of lymphocyte migration during immune responses. The expression and the function of the chemokine receptor XCR1 on breast cancer have remained elusive to date. In this study, the expressions of XCR1 mRNA were tested by quantitative real-time polymerase chain reaction in one breast epithelial cell line (MCF-10A) and nine breast cancer cell lines (MDA-MB-231, 231HM, 231BO, MDA-MB-468, MCF-7, T47D, Bcap-37, ZR-75-30, and SK-BR-3). We established XCR1-overexpressing breast cancer cell line MDA-MB-231 (231/XCR1) in XCR1 low expression cell line MDA-MB-231 (231). The ability of proliferation, invasion, and metastasis was measured by CCK8, plate cloning formation, and transwell analysis, respectively, in XCR1-overexpressing breast cancer cell lines (231/XCR1) and their parental cell line MDA-MB-231/Vector (simplified as “231/Vector”); 5×10⁶/100 μL cells were inoculated in mammary fat pad of BALB/c nude mice. There were six BALB/c nude mice in the experimental group and control group. Protein expression was analyzed by cell immunofluorescence and Western blot. The growth of XCR1-overexpressing human breast cancer cell line MDA-MB-231 in vitro was restrained and tumorigenesis in vivo was also extenuated, its mechanism may involve in the inhibition of MAPK and PI3K/AKT/mTOR signaling pathway, but increase in LC3 expression. However, the overexpression of XCR1 in human breast cancer cell line MDA-MB-231 in vitro can promote the migration and invasion partially due to decreasing the protein level of β-catenin. Therefore, XCR1 can affect the biological characteristics of some special breast cancer cells through complex signal transduction pathway.

Chemotherapy induces adaptive drug resistance and metastatic potentials via phenotypic CXCR4-expressing cell state transition in ovarian cancer

Ovarian cancer (OVC) patients who receive chemotherapy often acquire drug resistance within one year. This can lead to tumor reoccurrence and metastasis, the major causes of mortality. We report a transient increase of a small distinctive CXCR4^High/CD24^Low cancer stem cell population (CXCR4^High) in A2780 and SKOV-3 OVC cell lines in response to cisplatin, doxorubicin, and paclitaxel, treatments. The withdrawal of the drug challenges reversed this cell-state transition. CXCR4^High exhibits dormancy in drug resistance and mesenchymal-like invasion, migration, colonization, and tumor formation properties. The removal of this cell population from a doxorubicin-resistant A2780 lineage (A2780/ADR) recovered the sensitivity to drug treatments. A cytotoxic peptide (CXCR4-KLA) that can selectively target cell-surface CXCR4 receptor was further synthesized to investigate the therapeutic merits of targeting CXCR4^High. This peptide was more potent than the conventional CXCR4 antagonists (AMD3100 and CTCE-9908) in eradicating the cancer stem cells. When used together with cytotoxic agents such as doxorubicin and cisplatin, the combined drug-peptide regimens exhibited a synergistic cell-killing effect on A2780, A2780/ADR, and SKOV-3. Our data suggested that chemotherapy could establish drug-resistant and tumor-initiating properties of OVC via reversible CXCR4 cell state transition. Therapeutic strategies designed to eradicate rather than antagonize CXCR4^High might offer a far-reaching potential as supportive chemotherapy.

Adenosine arrests breast cancer cell motility by A3 receptor stimulation

In neutrophils, adenosine triphosphate (ATP) release and autocrine purinergic signaling regulate coordinated cell motility during chemotaxis. Here, we studied whether similar mechanisms regulate the motility of breast cancer cells. While neutrophils and benign human mammary epithelial cells (HMEC) form a single leading edge, MDA-MB-231 breast cancer cells possess multiple leading edges enriched with A3 adenosine receptors. Compared to HMEC, MDA-MB-231 cells overexpress the ectonucleotidases ENPP1 and CD73, which convert extracellular ATP released by the cells to adenosine that stimulates A3 receptors and promotes cell migration with frequent directional changes. However, exogenous adenosine added to breast cancer cells or the A3 receptor agonist IB-MECA dose-dependently arrested cell motility by simultaneous stimulation of multiple leading edges, doubling cell surface areas and significantly reducing migration velocity by up to 75 %. We conclude that MDA-MB-231 cells, HMEC, and neutrophils differ in the purinergic signaling mechanisms that regulate their motility patterns and that the subcellular distribution of A3 adenosine receptors in MDA-MB-231 breast cancer cells contributes to dysfunctional cell motility. These findings imply that purinergic signaling mechanisms may be potential therapeutic targets to interfere with the motility of breast cancer cells in order to reduce the spread of cancer cells and the risk of metastasis.

Blood vessel endothelium-directed tumor cell streaming in breast tumors requires the HGF/C-Met signaling pathway

During metastasis to distant sites, tumor cells migrate to blood vessels. In vivo, breast tumor cells utilize a specialized mode of migration known as streaming, where a linear assembly of tumor cells migrate directionally towards blood vessels on fibronectin-collagen I-containing extracellular matrix (ECM) fibers in response to chemotactic signals. We have successfully reconstructed tumor cell streaming in vitro by co-plating tumors cells, macrophages and endothelial cells on 2.5 μm thick ECM-coated micro-patterned substrates. We found that tumor cells and macrophages, when plated together on the micro-patterned substrates, do not demonstrate sustained directional migration in only one direction (sustained directionality) but show random bi-directional walking. Sustained directionality of tumor cells as seen in vivo was established in vitro when beads coated with human umbilical vein endothelial cells were placed at one end of the micro-patterned 'ECM fibers' within the assay. We demonstrated that these endothelial cells supply the hepatocyte growth factor (HGF) required for the chemotactic gradient responsible for sustained directionality. Using this in vitro reconstituted streaming system, we found that directional streaming is dependent on, and most effectively blocked, by inhibiting the HGF/C-Met signaling pathway between endothelial cells and tumor cells. Key observations made with the in vitro reconstituted system implicating C-Met signaling were confirmed in vivo in mammary tumors using the in vivo invasion assay and intravital multiphoton imaging of tumor cell streaming. These results establish HGF/C-Met as a central organizing signal in blood vessel-directed tumor cell migration in vivo and highlight a promising role for C-Met inhibitors in blocking tumor cell streaming and metastasis in vivo, and for use in human trials.

Laser Direct-Write Onto Live Tissues: A Novel Model for Studying Cancer Cell Migration

Investigation into the mechanisms driving cancer cell behavior and the subsequent development of novel targeted therapeutics requires comprehensive experimental models that mimic the complexity of the tumor microenvironment. Recently, our laboratories have combined a novel tissue culture model and laser direct-write, a form of bioprinting, to spatially position single or clustered cancer cells onto ex vivo microvascular networks containing blood vessels, lymphatic vessels, and interstitial cell populations. Herein, we highlight this new model as a tool for quantifying cancer cell motility and effects on angiogenesis and lymphangiogenesis in an intact network that matches the complexity of a real tissue. Application of our proposed methodology offers an innovative ex vivo tissue perspective for evaluating the effects of gene expression and targeted molecular therapies on cancer cell migration and invasion. J. Cell. Physiol. 231: 2333-2338, 2016. © 2016 Wiley Periodicals, Inc.

Exosomes enriched in stemness/metastatic-related mRNAS promote oncogenic potential in breast cancer

Cancer cells efficiently transfer exosome contents (essentially mRNAs and microRNAs) to other cell types, modifying immune responses, cell growth, angiogenesis and metastasis. Here we analyzed the exosomes release by breast tumor cells with different capacities of stemness/metastasis based on CXCR4 expression, and evaluated their capacity to generate oncogenic features in recipient cells. Breast cancer cells overexpressing CXCR4 showed an increase in stemness-related markers, and in proliferation, migration and invasion capacities. Furthermore, recipient cells treated with exosomes from CXCR4-cells showed increased in the same abilities. Moreover, inoculation of CXCR4-cell-derived exosomes in immunocompromised mice stimulated primary tumor growth and metastatic potential. Comparison of nucleic acids contained into exosomes isolated from patients revealed a “stemness and metastatic” signature in exosomes of patients with worse prognosis. Finally, our data supported the view that cancer cells with stem-like properties show concomitant metastatic behavior, and their exosomes stimulate tumor progression and metastasis. Exosomes-derived nucleic acids from plasma of breast cancer patients are suitable markers in the prognosis of such patients.

GLI1 orchestrates CXCR4/CXCR7 signaling to enhance migration and metastasis of breast cancer cells

The up-regulation of chemokine receptors CXCR4 and CXCR7 impacts on the distant metastasis and prognosis of breast cancer, though knowledge about the regulatory mechanism of their expressions is limited. Meanwhile, the GLI transcription factors of Hedgehog signaling have been reported to play a pivotal role in the development and progression of many types of human cancer. In breast cancer, the increased expression of GLI1 correlated with metastasis and unfavorable overall prognosis, though its molecular mechanism is also not fully understood. Based on our findings that GLI1 enhanced the lung metastasis of breast cancer cells in a mouse model system, we comprehensively screened for genes up-regulated by GLI1 in breast cancer cells, and as such identified CXCR4, CXCR7/ACKR3, and actin-binding protein LCP1/L-PLASTIN, all of which have been reported to be involved in CXCL12-stimulating signaling. In breast cancer cells, we found that GLI1 and GLI2 up-regulated these expressions, while treatment with GLI-specific inhibitor GANT61 reduced the expressions. As for CXCR4, we confirmed it as a direct target of GLI1 through the reporter assay and the chromatin immunoprecipitation assay. We also found that GLI1 enhanced CXCL12-induced ERK phosphorylation and cell migration, both of which were blocked by either CXCR4-specific inhibitor or knockdown of CXCR7 or LCP1. These evidences suggest an indispensable role of GLI1 in the migration and metastasis of breast cancer cells through CXCL12/CXCR4 signaling enhancement.

The metastasis inducer CCN1 (CYR61) activates the fatty acid synthase (FASN)-driven lipogenic phenotype in breast cancer cells

The angiogenic inducer CCN1 (Cysteine-rich 61, CYR61) is differentially activated in metastatic breast carcinomas. However, little is known about the precise mechanisms that underlie the pro-metastatic actions of CCN1. Here, we investigated the impact of CCN1 expression on fatty acid synthase (FASN), a metabolic oncogene thought to provide cancer cells with proliferative and survival advantages. Forced expression of CCN1 in MCF-7 cells robustly up-regulated FASN protein expression and also significantly increased FASN gene promoter activity 2- to 3-fold, whereas deletion of the sterol response element-binding protein (SREBP) binding site in the FASN promoter completely abrogated CCN1-driven transcriptional activation. Pharmacological blockade of MAPK or PI-3'K activation similarly prevented the ability of CCN1 to induce FASN gene activation. Pharmacological inhibition of FASN activity with the mycotoxin cerulenin or the small compound C75 reversed CCN1-induced acquisition of estrogen independence and resistance to hormone therapies such as tamoxifen and fulvestrant in anchorage-independent growth assays. This study uncovers FASNdependent endogenous lipogenesis as a new mechanism controlling the metastatic phenotype promoted by CCN1. Because estrogen independence and progression to a metastatic phenotype are hallmarks of therapeutic resistance and mortality in breast cancer, this previously unrecognized CCN1-driven lipogenic phenotype represents a novel metabolic target to clinically manage metastatic disease progression.