CXCR4 expression in early breast cancer and risk of distant recurrence

Recent advances targeting chemokines for breast cancer

Breast cancer (BC) is a complex and heterogeneous disease, and its onset and progression involve the interplay of multiple molecular mechanisms. Chemokines and their receptors are key regulators of cell migration and immune responses and contribute significantly to the pathophysiology of BC. This article reviews the classification, functions, and mechanisms of chemokines and their receptors in the proliferation, migration, invasion, and angiogenesis of BC cells. This study explores the regulatory roles of chemokines and their receptors in the immune microenvironment of BC, particularly the ways they influence the infiltration, polarization, and antitumor immune responses of immune cells. Finally, this article summarizes the current treatment strategies for breast cancer that utilize chemokines and their receptors and provides insights into future research directions and trends in this field.

New Emerging Chemokine Receptors: CCR5 or CXCR5 on Tumor Is Associated with Poor Response to Chemotherapy and Poor Prognosis in Locally Advanced Triple-Negative Breast Cancer

BACKGROUND

We aim to investigate any possible associations between chemokine receptor expression and responses to neoadjuvant chemotherapy (NAC) along with outcomes in patients with triple-negative breast cancer (TNBC) with locally advanced disease.

METHOD

Expressions of chemokine receptors were examined immunohistochemically after staining archival tissue of surgical specimens (n = 63) using specific antibodies for CCR5, CCR7, CXCR4, and CXCR5.

RESULTS

Patients with high CCR5, CCR7, CXCR4, and CXCR5 expression on tumors and high CXCR4 expression on tumor-infiltrating lymphocytes (TILs) were less likely to have a pathological complete response (pCR) or Class 0-I RCB-Index compared to others. Patients with residual lymph node metastases (ypN-positive), high CCR5TM(tumor), and high CXCR4TM expressions had an increased hazard ratio (HR) compared to others (DFS: HR = 2.655 [1.029-6.852]; DSS: HR = 2.763 [1.008-7.574]), (DFS: HR = 2.036 [0.805-5.148]; DSS: HR = 2.689 [1.020-7.090]), and (DFS: HR = 2.908 [1.080-7.829]; DSS: HR = 2.132 (0.778-5.846)), respectively. However, patients without CXCR5TIL expression had an increased HR compared to those with CXCR5TIL (DFS: 2.838 [1.266-6.362]; DSS: 4.211 [1.770-10.016]).

CONCLUSIONS

High expression of CXCR4TM and CCR5TM was found to be associated with poor prognosis, and CXCR5TM was associated with poor chemotherapy response in the present cohort with locally advanced TNBC. Our results suggest that patients with TNBC could benefit from a chemokine receptor inhibitor therapy containing neoadjuvant chemotherapy protocols.

Multifaceted roles of lymphatic and blood endothelial cells in the tumor microenvironment of hepatocellular carcinoma: A comprehensive review

The tumor microenvironment is a complex network of cells, extracellular matrix, and signaling molecules that plays a critical role in tumor progression and metastasis. Lymphatic and blood vessels are major routes for solid tumor metastasis and essential parts of tumor drainage conduits. However, recent studies have shown that lymphatic endothelial cells (LECs) and blood endothelial cells (BECs) also play multifaceted roles in the tumor microenvironment beyond their structural functions, particularly in hepatocellular carcinoma (HCC). This comprehensive review summarizes the diverse roles played by LECs and BECs in HCC, including their involvement in angiogenesis, immune modulation, lymphangiogenesis, and metastasis. By providing a detailed account of the complex interplay between LECs, BECs, and tumor cells, this review aims to shed light on future research directions regarding the immune regulatory function of LECs and potential therapeutic targets for HCC.

Distinguished biomimetic dECM system facilitates early detection of metastatic breast cancer cells

Breast cancer is the most prevalent malignant tumor affecting women's health. Bone is the most common distant metastatic organ, worsening the quality of life and increasing the mortality of patients. Early detection of breast cancer bone metastasis is urgent for halting disease progression and improving tumor prognosis. Recently, extracellular matrix (ECM) with biomimetic tissue niches opened a new avenue for tumor models in vitro. Here, we developed a biomimetic decellularized ECM (dECM) system to recapitulate bone niches at different situations, bone mimetic dECM from osteoblasts (BM-ECM) and bone tumor mimetic dECM from osteosarcoma cells (OS-ECM). The two kinds of dECMs exhibited distinct morphology, protein composition, and distribution. Interestingly, highly metastatic breast cancer cells tended to adhere and migrate on BM-ECM, while lowly metastatic breast cancer cells preferred the OS-ECM niche. Epithelial-to-mesenchymal transition was a potential mechanism to initiate the breast cancer cell migration on different biomimetic dECMs. Importantly, in the nude mice model, the dECM system captured metastatic breast cancer cells as early as 10 days after orthotopic transplantation in mammary gland pads, with higher signal on BM-ECM than that on OS-ECM. Collectively, the biomimetic dECM system might be a promising tumor model to distinguish the metastatic ability of breast cancer cells in vitro and to facilitate early detection of metastatic breast cancer cells in vivo, contributing to the diagnosis of breast cancer bone metastasis.

Evaluation of the influence of the C-X-C motif chemokine ligand 12 / C-X-C chemokine receptor 4 axis on canine mammary gland tumor cell migration

C-X-C motif chemokine ligand 12 (CXCL12) is one of the chemokines that binds to C-X-C chemokine receptor 4 (CXCR4) on tumor cell membranes and induces chemotaxis and/or migration. Mammary gland tumors (MGT) are the most common neoplasms in intact female dogs, with local invasion and distant metastasis regarded as problems. However, the influence of the CXCL12/CXCR4 axis on canine MGT cell migration has not been elucidated. This study aimed to evaluate the expression of CXCL12 and CXCR4 in canine MGT cells and tissues and investigate the influence of CXCL12 protein on the migratory ability of MGT cells. CXCL12 expression was evaluated in 10 canine malignant MGT tissues. CXCL12 expression in tumor cells was identified in all examined tissues; however, the staining pattern and intensity differed between the tumors. Immunocytochemistry revealed three canine MGT cell lines as CXCR4-positive. Migratory ability was evaluated using a wound healing assay, and the migration of CXCR4-positive MGT cells was significantly activated by the addition of CXCL12 protein. This influence was canceled by pre-treatment with a CXCR4 antagonist. The results of our study suggest that the CXCL12/CXCR4 axis may be associated with the migration of canine MGT.

The Effect of Hypoxia on the Expression of CXC Chemokines and CXC Chemokine Receptors-A Review of Literature

Hypoxia is an integral component of the tumor microenvironment. Either as chronic or cycling hypoxia, it exerts a similar effect on cancer processes by activating hypoxia-inducible factor-1 (HIF-1) and nuclear factor (NF-κB), with cycling hypoxia showing a stronger proinflammatory influence. One of the systems affected by hypoxia is the CXC chemokine system. This paper reviews all available information on hypoxia-induced changes in the expression of all CXC chemokines (CXCL1, CXCL2, CXCL3, CXCL4, CXCL5, CXCL6, CXCL7, CXCL8 (IL-8), CXCL9, CXCL10, CXCL11, CXCL12 (SDF-1), CXCL13, CXCL14, CXCL15, CXCL16, CXCL17) as well as CXC chemokine receptors—CXCR1, CXCR2, CXCR3, CXCR4, CXCR5, CXCR6, CXCR7 and CXCR8. First, we present basic information on the effect of these chemoattractant cytokines on cancer processes. We then discuss the effect of hypoxia-induced changes on CXC chemokine expression on the angiogenesis, lymphangiogenesis and recruitment of various cells to the tumor niche, including myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), regulatory T cells (T_regs) and tumor-infiltrating lymphocytes (TILs). Finally, the review summarizes data on the use of drugs targeting the CXC chemokine system in cancer therapies.

Widespread Metastasis to the Stomach 10 Years After Primary Breast Cancer: A case report and review of the literature

RATIONALE

Breast cancer is a common malignant tumor. The most common metastatic sites of breast cancer are the bone, brain, liver and lung, and gastrointestinal metastases are rare. Considering that the median time interval from the initial breast cancer diagnosis to stomach metastasis is 77.5 months, gastrointestinal metastases are rarely observed 10 years after primary breast cancer.

PATIENT CONCERNS

Here, we present a 63-year-old female with unusual endoscopy results that revealed scattered polyps and mucosal infiltration throughout the stomach, which were later confirmed to be metastatic lobular carcinoma of the breast that had been surgically removed 10 years earlier.

DIAGNOSIS

The patient was diagnosed with gastric metastases of breast cancer by immunohistochemistry.

INTERVENTIONS

The patient underwent endocrine therapy with palbociclib and tamoxifen.

OUTCOMES

After 1 year of endocrine therapy, the symptoms of upper abdominal discomfort and fatigue were relieved and a new gastroscopy revealed there had been no significant progression of the gastric metastasis. According to the Response Evaluation Criteria in Solid Tumors (RECIST), the patient reached a state of stable disease.

LESSONS

Gastric metastases of breast cancer are rare in the clinical setting. However, considering the possibility of gastric metastases from breast cancer and performing an upper endoscopy are crucial for patients who present with any subtle gastric symptoms and have a past medical history of breast cancer, even if the breast cancer occurred more than 10 years ago.

Clinical Significance of C-X-C Motif Chemokine Receptor 4 and Integrin αvβ6 Expression in Breast Cancer

Purpose

C-X-C motif chemokine receptor 4 (CXCR4) and integrin αvβ6 play important roles in the malignant progression of multiple cancers. However, it remains unclear whether the expression of one or both proteins in breast cancer (BC) is of clinical significance. In this study, we investigated the expression of CXCR4 and integrin αvβ6 in BC tissues and their correlation with clinicopathological characteristics, including survival.

Methods

CXCR4 and αvβ6 expression in 111 BC tissues was examined by immunocytochemistry. Correlations between the expression of the 2 proteins and patient clinicopathological characteristic were investigated using the Kaplan–Meier method and the Cox proportional hazards model.

Results

CXCR4 and αvβ6 were overexpressed in BC tissue compared with normal breast tissue. Overexpression of both molecules was related to lymph node status (p = 0.013 and p = 0.022, respectively). αvβ6 overexpression was also associated with tumor size (p = 0.044). A positive correlation was detected between the expression of CXCR4 and αvβ6 (r = 0.649, p = 0.001), and co-overexpression of both molecules was associated with tumor size (p = 0.018) and lymph node metastasis (p = 0.015). Kaplan–Meier analysis revealed that overexpression of CXCR4, αvβ6, or both molecules was associated with short overall survival (OS; p < 0.001, p < 0.001, and p = 0.009, respectively) and disease-free survival (DFS; p < 0.001, p = 0.005, and p = 0.019, respectively). Multivariate analysis indicated that lymph node metastasis was an independent prognostic factor for unfavorable OS and DFS (p = 0.002 and p = 0.005, respectively), whereas co-overexpression of CXCR4 and αvβ6 was an independent prognostic factor only for OS (p = 0.043).

Conclusion

CXCR4 and αvβ6 may play synergistic roles in the progression of BC, and co-targeting of CXCR4 and αvβ6 could be a potential strategy for the prevention and treatment of BC.

Chemokines and their Receptors: Multifaceted Roles in Cancer Progression and Potential Value as Cancer Prognostic Markers

Chemokines are chemotactic cytokines that mediate immune cell chemotaxis and lymphoid tissue development. Recent advances have indicated that chemokines and their cognate receptors play critical roles in cancer-related inflammation and cancer progression. On the basis of these findings, the chemokine system has become a new potential drug target for cancer immunotherapy. In this review, we summarize the essential roles of the complex network of chemokines and their receptors in cancer progression. Furthermore, we discuss the potential value of the chemokine system as a cancer prognostic marker. The chemokine system regulates the infiltration of immune cells into the tumor microenvironment, which induces both pro- and anti-immunity and promotes or suppresses tumor growth and proliferation, angiogenesis, and metastasis. Increasing evidence indicates the promising prognostic value of the chemokine system in cancer patients. While CCL2, CXCL10, and CX3CL1/CX3CR1 can serve as favorable or unfavorable prognostic factors depending on the cancer types, CCL14 and XCL1 possess good prognostic value. Other chemokines such as CXCL1, CXCL8, and CXCL12 are poor prognostic markers. Despite vast advances in our understanding of the complex nature of the chemokine system in tumor biology, knowledge about the multifaceted roles of the chemokine system in different types of cancers is still limited. Further studies are necessary to decipher distinct roles within the chemokine system in terms of cancer progression and to validate their potential value in cancer prognosis.

64Cu-Labeled Ubiquitin for PET Imaging of CXCR4 Expression in Mouse Breast Tumor

Ubiquitin has been recently identified as a chemokine receptor 4 (CXCR4) natural ligand, offering great potential for positron emission computed tomography (PET) imaging of CXCR4 expression. This study reports the preparation and evaluation of (64Cu)-radiolabeled ubiquitin for CXCR4 imaging. The ubiquitin was first fused with a C-terminal GGCGG sequence, and the resulting recombinant ubiquitin derivative UbCG4 was then functionalized with the trans-cyclooctene (TCO) moiety via thiol-maleimide click reaction, followed by 64Cu-radiolabeling through the TCO/Tz (tetrazine)-based Diels-Alder click reaction. In the prepared in vitro studies, the prepared (64Cu)-UbCG4 showed significantly higher specific uptakes in the 4T1 breast cancer cells compared with the uptakes in the CXCR4-knockdown 4T1 cells. In the in vivo evaluation in the 4T1-xenograft mouse model, (64Cu)-UbCG4 demonstrated a similar tumor uptake but much lower backgrounds compared with 64Cu-labeled AMD3465. These results suggested that (64Cu)-UbCG4 could serve as a potent PET tracer for the noninvasive imaging of CXCR4 expression in tumors.

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 and its ligand CXCL12 display opposite expression profiles in feline mammary metastatic disease, with the exception of HER2-overexpressing tumors

BACKGROUND

The receptor CXCR4 and its ligand CXCL12 play crucial roles in breast cancer. Despite the fact that the spontaneous feline mammary carcinoma (FMC) is considered a suitable model for breast cancer studies, the importance of the CXCR4/CXCL12 axis in FMC is completely unknown. Therefore, this work aims to elucidate the role of CXCR4 and its ligand in the progression of FMC and metastatic disease.

METHODS

CXCR4 and CXCL12 expression was analyzed by immunohistochemistry and immunofluorescence on primary tumors (PT), regional and distant metastases of female cats with mammary carcinoma and correlated with serum CXCL12 levels, tumor molecular subtypes and clinicopathological features.

RESULTS

CXCR4 was more expressed in PT than in metastases (p = 0.0067), whereas CXCL12 was highly expressed in metastatic lesions located in liver and lung (p < 0.0001), as reported for human breast cancer. Moreover, cats with CXCR4 positive PT exhibited significantly lower serum CXCL12 levels than cats with CXCR4 negative mammary carcinomas (p = 0.0324). At metastatic lesions, HER2-overexpressing tumors presented higher CXCR4 expression than the other molecular tumor subtypes (p = 0.012) and significant differences in overall (p = 0.0147) and disease-free survival (p = 0.0279) curves between the cats with CXCL12 positive and CXCL12 negative tumors were found. Indeed, CXCL12 negative PT were associated with unfavorable prognosis in cats with HER2-overexpressing tumors.

CONCLUSIONS

This work exposes part of the complex interaction between CXCR4 and CXCL12 in PT, but also in metastases of a breast cancer model. These findings could uncover novel therapeutic tools to be used in cats and humans.

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.

CRISPR/Cas9-mediated genome engineering of CXCR4 decreases the malignancy of hepatocellular carcinoma cells in vitro and in vivo

CXC chemokine receptor 4 (CXCR4) is associated with poor clinical outcomes and decreased survival in hepatocellular carcinoma (HCC). In the present study, we targeted CXCR4 by CRISPR/Cas9 in HepG2 cells and observed the effects both in vitro and in vivo. The results indicated that after targeting CXCR4 the expression of CXCR4 was significantly decreased and the cell proliferation was inhibited. Clonogenicity and scratch cell migration assays indicated that specific downregulation of CXCR4 inhibited cell migration. This disruption of CXCR4 led to less invasiveness, the genes related to epithelial-mesenchymal transition (EMT) and cell self-renewal were also affected. Moreover, sensitivity to the anticancer drug cisplatin was significantly increased in vitro by the downregulation of CXCR4. The results of the in vivo study showed that the growth volumes were significantly smaller in neoplasms derived from CXCR4-downregulated HepG2 cells compared to those derived from wild-type cells. These results showed that targeting CXCR4 by CRISPR/Cas9 could inhibit proliferation, migration and invasion, reversed EMT, increased chemosensitivity and decrease the malignancy of HCC in vitro and in vivo.

Gastric and colon metastasis from breast cancer: case report, review of the literature, and possible underlying mechanisms

Gastrointestinal metastases from breast cancer are not common. We present a 58-year-old female diagnosed with lobular breast cancer some years before whose relapses were gastric and colonic mucosal. Simultaneous metastases are extremely rare. To our knowledge, no cases of initial dual affectation have been reported. The patient also showed gastritis by Helicobacter pylori. Invasive lobular breast carcinoma is the most frequent special type of breast cancer and carries some specific molecular alterations such as loss of expression of E-cadherin. Although underlying mechanisms of metastasization are not entirely known, chemokines as well as inflammatory events seem to be implicated in this process. Interaction between chemokines and their receptors frequently induces cell migration. We hypothesize that H. pylori, inflammatory cells, and chemokines may create a favorable environment attracting tumor cells.

CXCR4 over-expression and survival in cancer: a system review and meta-analysis

C-X-C chemokine receptor 4 (CXCR4) is frequently over-expressed in various types of cancer; many agents against CXCR4 are in clinical development currently despite variable data for the prognostic impact of CXCR4 expression. Here eighty-five studies with a total of 11,032 subjects were included to explore the association between CXCR4 and progression-free survival (PFS) or overall survival (OS) in subjects with cancer. Pooled analysis shows that CXCR4 over-expression is significantly associated with poorer PFS (HR 2.04; 95% CI, 1.72-2.42) and OS (HR=1.94; 95% CI, 1.71-2.20) irrespective of cancer types. Subgroup analysis indicates significant association between CXCR4 and shorter PFS in hematological malignancy, breast cancer, colorectal cancer, esophageal cancer, renal cancer, gynecologic cancer, pancreatic cancer and liver cancer; the prognostic effects remained consistent across age, risk of bias, levels of adjustment, median follow-up period, geographical area, detection methods, publication year and size of studies. CXCR4 over-expression predicts unfavorable OS in hematological malignancy, breast cancer, colorectal cancer, esophageal cancer, head and neck cancer, renal cancer, lung cancer, gynecologic cancer, liver cancer, prostate cancer and gallbladder cancer; these effects were independence of age, levels of adjustment, publication year, detection methods and follow-up period. In conclusion, CXCR4 over-expression is associated with poor prognosis in cancer.

Potential of CXCR4/CXCL12 Chemokine Axis in Cancer Drug Delivery

This review discusses the potential of CXCR4 chemokine receptor in the design of anticancer and antimetastatic drug delivery systems. The role of CXCR4 in cancer progression and metastasis is discussed in the context of the development of several types of drug delivery strategies. Overview of drug delivery systems targeted to cancers that overexpress CXCR4 is provided, together with the main types of CXCR4-binding ligands used in targeting applications. Drug delivery applications that take advantage of CXCR4 inhibition to achieve enhanced anticancer and antimetastatic activity of combination treatments are also discussed.

Positron emission tomographic imaging of CXCR4 in cancer: challenges and promises

Molecular imaging is an attractive platform for noninvasive detection and assessment of cancer. In recent years, the targeted imaging of the C-X-C chemokine receptor 4 (CXCR4), a chemokine receptor that has been associated with tumor metastasis, has become an area of intensive research. This review article focuses on positron emission tomography (PET) and aims to provide useful and critical insights into the application of PET to characterize CXCR4 expression, including the chemical, radiosynthetic, and biological requirements for PET radiotracers. This discussion is informed by a summary of the different approaches taken so far and a comparison of their clinical translation. Finally, our expert opinions as to potential future advances in the field are expressed.

Nef-M1, a peptide antagonist of CXCR4, inhibits tumor angiogenesis and epithelial‑to‑mesenchymal transition in colon and breast cancers

The Nef-M1 peptide competes effectively with the natural ligand of CXC chemokine receptor 4 (CXCR4), stromal cell-derived factor 1-alpha, to induce apoptosis and inhibit growth in colon cancer (CRC) and breast cancer (BC). Its role in tumor angiogenesis, and epithelial-to-mesenchymal transition (EMT) regulation, key steps involved in tumor growth and metastasis, are unknown. We evaluated the angioinhibitory effect of Nef-M1 peptide and examined its role in the inhibition of EMT in these cancers. Colon (HT29) and breast (MDA-MB231) cancer cells expressing CXCR4 were studied in vitro and in xenograft tumors propagated in severe combined immunodeficient mice. The mice were treated intraperitoneally with Nef-M1 or scrambled amino acid sequence of Nef-M1 (sNef-M1) peptide, a negative control, starting at the time of tumor implantation. Sections from tumors were evaluated for tumor angiogenesis, as measured by microvessel density (MVD) based on immunostaining of endothelial markers. In vitro tumor angiogenesis was assessed by treating human umbilical vein endothelial cells with conditioned media from the tumor cell lines. A BC cell line (MDA-MB 468) which does not express CXCR4 was used to study the actions of Nef-M1 peptide. Western blot and immunofluorescence analyses assessed the effect of Nef-M1 on tumor angiogenesis and EMT in both tumors and cancer cells. Metastatic lesions of CRC and BC expressed more CXCR4 than primary lesions. It was also found that tumors from mice treated with sNef-M1 had well established vascularity, while Nef-M1 treated tumors had very poor vascularization. Indeed, the mean MVD was lower in tumors from Nef-M1 treated mice than in sNef-M1 treated tumors. Nef-M1 treated tumor has poor morphology and loss of endothelial integrity. Although conditioned medium from CRC or BC cells supported HUVEC tube formation, the conditioned medium from Nef-M1 treated CRC or BC cells did not support tube formation. Western blot analyses revealed that Nef-M1 effectively suppressed the expression of VEGF-A in CRC and BC cells and tumors. This suggests that Nef-M1 treated CRC and BC cells are more consistent with E-cadherin signature, and thus appears more epithelial in nature. Our data indicate that Nef-M1 peptide inhibits tumor angiogenesis and the oncogenic EMT process. Targeting the chemokine receptor, CXCR4, mediated pathways using Nef-M1 may prove to be a novel therapeutic approach for CRC and BC.

CXCR4 Protein Epitope Mimetic Antagonist POL5551 Disrupts Metastasis and Enhances Chemotherapy Effect in Triple-Negative Breast Cancer

The SDF-1 receptor CXCR4 has been associated with early metastasis and poorer prognosis in breast cancers, especially the most aggressive triple-negative subtype. In line with previous reports, we found that tumoral CXCR4 expression in patients with locally advanced breast cancer was associated with increased metastases and rapid tumor progression. Moreover, high CXCR4 expression identified a group of bone marrow-disseminated tumor cells (DTC)-negative patients at high risk for metastasis and death. The protein epitope mimetic (PEM) POL5551, a novel CXCR4 antagonist, inhibited binding of SDF-1 to CXCR4, had no direct effects on tumor cell viability, but reduced migration of breast cancer cells in vitro. In two orthotopic models of triple-negative breast cancer, POL5551 had little inhibitory effect on primary tumor growth, but significantly reduced distant metastasis. When combined with eribulin, a chemotherapeutic microtubule inhibitor, POL5551 additively reduced metastasis and prolonged survival in mice after resection of the primary tumor compared with single-agent eribulin. Hypothesizing that POL5551 may mobilize tumor cells from their microenvironment and sensitize them to chemotherapy, we used a "chemotherapy framing" dosing strategy. When administered shortly before and after eribulin treatment, three doses of POL5551 with eribulin reduced bone and liver tumor burden more effectively than chemotherapy alone. These data suggest that sequenced administration of CXCR4 antagonists with cytotoxic chemotherapy synergize to reduce distant metastases.

Immunohistochemical expression of CXCR4 on breast cancer and its clinical significance

Many tumor cells express chemokines and chemokine receptors, and, for this reason, these molecules can affect the tumor progression. It is known that breast cancer is a complex and heterogeneous neoplasia comprising distinct diseases, histological characteristics, and clinical outcomes. The most studied role for CXCL12 chemokine and its receptor CXCR4 in breast cancer pathogenesis is the metastasis event, although several reports have demonstrated its involvement in other processes, such as angiogenesis and tumor growth. It has been found that CXCR4 is required for breast cancer cell migration to other sites such as lung, bone, and lymph nodes, which express high levels of CXCL12 chemokine. Therefore, CXCR4 is being considered a prognostic marker in breast cancer. Within this context, this review summarizes established studies involving expression of CXCR4 on breast cancer, focusing on its clinical significance.

Immunohistochemical Predictors of Bone Metastases in Breast Cancer Patients

Bones are the most common metastatic site of relapse in breast cancer patients and the prediction of bone metastases (BM) risk might prompt developing preventive and therapeutic strategies. The aim of the study was to correlate imumohistochemical (IHC) expression of selected proteins in primary breast cancer with the occurrence of BM. We analyzed expression of proteins potentially associated with BM in primary tumors of 184 patients with metastatic breast cancer (113 with- and 71 without BM). Expression of estrogen receptor (ER) in primary tumor was more common in patients with- compared to those without BM (74 vs. 45 % respectively, p = 0.0001), whereas in this subset less common was expression of parathyroid hormone related protein receptor type 1 (16 vs. 34 %, respectively, p = 0.007) and cytoplasmic expression of osteopontin (OPNcyt; 1.9 vs. 14 %, respectively, p = 0.002). The relationship between expression of ER and OPNcyt and the occurrence of BM was confirmed in the multivariate analysis. The ER-positive/OPNcyt negative phenotype was significantly more common in patients with- compared to those without BM (75 and 25 %, p < 0.0001, respectively; HR 1.79, p = 0.013). Luminal A (43 vs. 23 % respectively, p = 0.009) and luminal B/HER2-positive (16 vs. 4.9 % respectively, p = 0.032) subtypes were more common in patients with- compared to those without BM, whereas triple negative breast cancer subtype was less common (16 vs. 38 %, p = 0.002).

[Prognostic values of the clinical, morphological and molecular biological characteristics of colon adenocarcinoma]

OBJECTIVE

to estimate the predictive and prognostic factors using morphological studies in patients with colon cancer to increase survival rates.

SUBJECTS AND METHODS

Immunohistochemical examination was made in 582 patients with colon adenocarcinoma, by determining 11 different indicators relating to the development of the tumor and its treatment.

RESULTS

The simultaneous determination of the chemokine receptor CXCR4 and proliferative activity (Ki-67 expression) can define disease prognosis in view of relapse-survival rates in patients with Stage II colon cancer after radical surgical treatment.

CONCLUSION

Thymidylate synthase and thymidine phosphorylase are of predictive value. The immunohistochemical examination of other markers, such as ALDH1, CCR10, ERCC-1, DYPD, topoisomerase II alpha, and class III beta-tubulin for the choice of treatment policy for patients with colon cancer has indicated that they are of no value.

Activation of STAT3 is involved in malignancy mediated by CXCL12-CXCR4 signaling in human breast cancer

The chemokine receptor CXCR4 and signal transducer and activator of transcription 3 (STAT3) play an important role in breast cancer malignancy and metastasis. However, it remains unknown whether STAT3 can be activated by CXCR4 in human breast cancer. The expression levels of CXCR4, STAT3 and p-STAT3 in 208 breast cancer tissues and 26 tumor-adjacent tissues were examined by immunohistochemistry. Flow cytometry, western blot analysis and immunoprecipitation were used to study activation of STAT3 by CXCL12-CXCR4 signaling in human breast cancer cell lines. The expression levels of CXCR4, STAT3 and p-STAT3 were higher in the breast cancer samples than these levels in the tumor-adjacent samples. The combined expression of CXCR4 and p-STAT3 was correlated with TNM stage, tumor size, lymph node metastasis and histological grade of breast cancer. In the breast cancer cells, CXCL12 treatment increased the expression of p-STAT3. The CXCR4 antagonist AMD3100 and the Janus kinase 2 (JAK2) antagonist AG490 inhibited the CXCL12-induced increase in the phosphorylation of STAT3. Furthermore, CXCL12 promoted direct binding of JAK2 to CXCR4. Our findings suggest that activation of the JAK2/STAT3 pathway via CXCL12-CXCR4 signaling plays an important role in breast cancer malignancy and metastasis. Targeting the CXCL12-CXCR4/JAK2/STAT3 signaling pathway may be a potential therapeutic strategy for the treatment of breast cancer.

Chemokine (C-X-C motif) receptor 4 RNA interference inhibits bone metastasis in breast cancer

Chemokine (C-X-C motif) receptor 4 (CXCR4) has been found to closely correlate with the incidence, development, treatment and prognosis of breast cancer. The aim of the present study was to investigate the effects of CXCR4 on bone metastasis in breast cancer and to explore the mechanisms of this process. CXCR4 small interfering RNA was transfected into the breast cancer cell line, MDA-MB-231BA-rfp, and the cell proliferation and invasion abilities of the cells were measured using cell counting kit-8 cell proliferation and Transwell assays. A mouse model of breast cancer with bone metastasis was prepared and the bone metastasis was confirmed using micro-positron emission tomography. The associated proteins were detected by western blot analysis and the results showed that CXCR4 RNAi inhibited the cell proliferation and invasion ability of the MDA-MB-231BA-rfp cells. In addition, CXCR4 RNAi inhibited the duration and extent of bone metastasis in the MDA-MB-231BA-rfp cells in the mouse model, while the inhibition of CXCR4 RNAi blocked the phosphatidylinositide 3-kinase (PI3K)/protein kinase B (AKT)/matrix metalloproteinase (MMP)-9 pathway. In conclusion, the present study demonstrated that CXCR4 RNAi inhibits bone metastasis and the cell proliferation and invasion abilities of breast cancer cells. Furthermore, the CXCR4/PI3K/AKT/MMP-9 pathway may be important in the bone metastasis of breast cancer.

Effect of biodegradability on CXCR4 antagonism, transfection efficacy and antimetastatic activity of polymeric Plerixafor

Chemokine receptor CXCR4 and its sole ligand SDF-1 are key players in regulating cancer cell invasion and metastasis. Plerixafor (AMD3100) is a small-molecule CXCR4 antagonist that prevents binding of SDF-1 to CXCR4 and has potential in prevention of cancer metastasis. This study investigates the influence of biodegradability of a recently reported polymeric Plerixafor (PAMD) on CXCR4 antagonism, antimetastatic activity, and transfection efficacy of PAMD polyplexes with plasmid DNA. We show that PAMD exhibits CXCR4 antagonism and inhibition of cancer cell invasion in vitro regardless of its biodegradability. Biodegradable PAMD showed considerably enhanced transfection efficiency and decreased cytotoxicity when compared with the non-degradable PAMD. Despite similar CXCR4 antagonism in vitro, only biodegradable PAMD displayed antimetastatic activity in experimental lung metastasis model in vivo.

Expression of CXCR4 and breast cancer prognosis: a systematic review and meta-analysis

Background

The chemokine receptor CXCR4 plays a significant role in biological processes, as well as in tumorigenesis and the progression of cancer, especially breast cancer. However, the clinical application of CXCR4 for breast cancer prognosis is still very limited. A meta-analysis based on published studies was performed with the aim of obtaining an accurate evaluation of the relationship between CXCR4 expression and the prognosis of breast cancer.

Methods

A comprehensive search strategy was used to search relevant literature in PubMed, MEDLINE and the ISI Web of Science. The correlation between CXCR4 expression and clinicopathological features and breast cancer prognosis was analyzed. This meta-analysis was carried out using Review Manager 4.2.

Result

Thirteen eligible studies consisting of 3865 participants were included. We found that breast cancers with CXCR4 expression were associated with lymph node status (pooled RR =1.20, 95% CI: 1.01-1.43, P<0.001) and distant metastasis (pooled RR =1.52, 95% CI: 1.17-1.98, P = 0.125). CXCR4 overexpression was significantly associated with disease free survival (DFS) (RR = 0.77, 95% CI = 0.70–0.86, P = 0.554) and overall survival (OS) (RR = 0.70, 95% CI = 0.59–0.83, P = 0.329). However, there was no significant association between CXCR4 expression and some clinical parameters of breast cancer, such as tumor category, ER status, PR status, or c-erbB-2 status.

Conclusion

Our meta-analysis showed that CXCR4 is an efficient prognostic factor for breast cancer. Overexpression of CXCR4 was significantly associated with lymph node status and distant metastasis and indicated poor overall and disease free survival.

A radiogallium-DOTA-based bivalent peptidic ligand targeting a chemokine receptor, CXCR4, for tumor imaging

We have developed a novel radiogallium (Ga)-DOTA-based bivalent peptidic ligand targeting a chemokine receptor, CXCR4, for tumor imaging. A CXCR4 imaging probe with two CXCR4 antagonists (Ac-TZ14011) on Ga-DOTA core, Ga-DOTA-TZ2, was synthesized, and the affinity and binding to CXCR4 was evaluated in CXCR4 expressing cells in vitro. The affinity of Ga-DOTA-TZ2 for CXCR4 was 20-fold greater than the corresponding monovalent probe, Ga-DOTA-TZ1. (67)Ga-DOTA-TZ2 showed the significantly higher accumulation in CXCR4-expressing tumor cells compared with (67)Ga-DOTA-TZ1, suggesting the bivalent effect enhances its binding to CXCR4. The incorporation of two CXCR4 antagonists to Ga-DOTA could be effective in detecting CXCR4-expressing tumors.

The potential of hypoxia markers as target for breast molecular imaging--a systematic review and meta-analysis of human marker expression

Background

Molecular imaging of breast cancer is a promising emerging technology, potentially able to improve clinical care. Valid imaging targets for molecular imaging tracer development are membrane-bound hypoxia-related proteins, expressed when tumor growth outpaces neo-angiogenesis. We performed a systematic literature review and meta-analysis of such hypoxia marker expression rates in human breast cancer to evaluate their potential as clinically relevant molecular imaging targets.

Methods

We searched MEDLINE and EMBASE for articles describing membrane-bound proteins that are related to hypoxia inducible factor 1α (HIF-1α), the key regulator of the hypoxia response. We extracted expression rates of carbonic anhydrase-IX (CAIX), glucose transporter-1 (GLUT1), C-X-C chemokine receptor type-4 (CXCR4), or insulin-like growth factor-1 receptor (IGF1R) in human breast disease, evaluated by immunohistochemistry. We pooled study results using random-effects models and applied meta-regression to identify associations with clinicopathological variables.

Results

Of 1,705 identified articles, 117 matched our selection criteria, totaling 30,216 immunohistochemistry results. We found substantial between-study variability in expression rates. Invasive cancer showed pooled expression rates of 35% for CAIX (95% confidence interval (CI): 26-46%), 51% for GLUT1 (CI: 40-61%), 46% for CXCR4 (CI: 33-59%), and 46% for IGF1R (CI: 35-70%). Expression rates increased with tumor grade for GLUT1, CAIX, and CXCR4 (all p < 0.001), but decreased for IGF1R (p < 0.001). GLUT1 showed the highest expression rate in grade III cancers with 58% (45-69%). CXCR4 showed the highest expression rate in small T1 tumors with 48% (CI: 28-69%), but associations with size were only significant for CAIX (p < 0.001; positive association) and IGF1R (p = 0.047; negative association). Although based on few studies, CAIX, GLUT1, and CXCR4 showed profound lower expression rates in normal breast tissue and benign breast disease (p < 0.001), and high rates in carcinoma in situ. Invasive lobular carcinoma consistently showed lower expression rates (p < 0.001).

Conclusions

Our results support the potential of hypoxia-related markers as breast cancer molecular imaging targets. Although specificity is promising, combining targets would be necessary for optimal sensitivity. These data could help guide the choice of imaging targets for tracer development depending on the envisioned clinical application.

High-level expression of CXCR4 in breast cancer is associated with early distant and bone metastases

Metastasis is the most life-threatening complication in all cancers. The chemokine receptor 4 (CXCR4) is expressed at high levels in many breast-cancer tumors and may modulate metastasis. We compared the time-to-metastasis and the sites of metastasis between breast-cancer tumors expressing CXCR4 at high or low levels. We enrolled 191 early breast cancer patients in our study. The expression of CXCR4 was evaluated using immunohistochemical staining, and the patients were divided into low-level (CXCR4-) and high-level (CXCR4+) CXCR4 expression groups. Associations between the patients' level of CXCR4 expression and their basic clinical characteristics, time-to-metastasis, and metastatic sites were examined using a Cox proportional-hazards regression model. A total of 107 CXCR4+ patients (56 %) were identified. No statistical differences were evident in basic characteristics between the CXCR4+ and CXCR4- groups. The CXCR4+ group had a higher incidence of distant metastasis during the first year (10.3 % versus 1.1 %, P = 0.009) and shorter event-free survival (17.43 months versus 27.5 months, P = 0.026) than those of the CXCR4- group. The CXCR4+ group also had a higher incidence of bone metastasis (P = 0.008) than the CXCR4- group. No significant difference in metastasis sites in other organs was observed between the two groups. A high level of CXCR4 expression in breast cancer is associated with early distant and bone metastases. The CXCR4+ phenotype may be a useful predictor for the prevention of early treatment failure and bone metastasis in breast cancer patients. This retrospective study shows that a high expression of CXCR4 in breast cancer is associated with earlier distant metastasis and bone metastasis in breast cancer.

The impact of chemokine receptor CXCR4 on breast cancer prognosis: a meta-analysis

BACKGROUND

C-X-C chemokine receptor type 4 (CXCR4) has been implicated in the invasiveness and metastasis of diverse cancers. However, the published data remain controversial on the correlation between CXCR4 expression level, as well as its subcellular distribution in tumor cells, and the clinical outcome of patients with breast cancer.

METHODS

To identify the precise role of CXCR4 in the clinical outcome of breast cancer, we performed a meta-analysis including 15 published studies. Original data included the hazard ratios (HRs) of overall survival (OS) and disease-free survival (DFS) in breast cancer with high CXCR4 expression versus low expression. We pooled hazard ratios (HRs) with 95% confidence intervals (CIs) to estimate the hazard.

RESULTS

A total of 15 published studies (including 3104 patients) were eligible. Overall survival (OS) and disease-free survival (DFS) of breast cancer were found to be significantly related to CXCR4 expression level, with the HR being 1.65 (95%CI: 1.34-2.03; P<0.00001) and 1.94 (95%CI: 1.42-2.65; P<0.00001) respectively. Stratified analysis according to subcellular distribution of CXCR4 showed that high expression in whole cells, cytoplasm and nucleus could predict unfavorable OS, with the HR of 2.02 (95%CI: 1.43-2.85; P<0.0001), 1.57 (95%CI: 1.13-2.18; P=0.007), and 1.47 (95%CI: 1.19-1.81; P=0.0004) respectively. As for DFS, elevated expression level of CXCR4 both in whole cells and cytoplasm predicted a poor outcome, with the HR being 2.23 (95%CI: 1.48-3.37; P=0.0001) and 1.76 (95%CI: 1.11-2.80; P=0.02), while high expression in the nucleus had no statistical significance, with HR 1.15 (95%CI: 0.52-2.55; P=0.73).

CONCLUSIONS

Increased CXCR4 expression, especially in whole cells and cytoplasm, may serve as a poor prognostic indicator in patients with breast cancer. Future studies are warranted to investigate the relationship between CXCR4 expression and survival of patients with breast carcinoma, which could help predict the clinical outcome and guide clinical decision-making for therapy.

Concomitant overexpression of EGFR and CXCR4 is associated with worse prognosis in a new molecular subtype of non-small cell lung cancer

Although the relationships between CXCR4 and EGFR expression and survival in non‑small cell lung cancer (NSCLC) have been studied independently, dual CXCR4/EGFR tumor status and its relationship with survival has not been previously investigated. In the present study, we examined the relationship between CXCR4 expression, EGFR expression and dual CXCR4/EGFR expression and survival in patients with NSCLC (n=125) using immunohistochemical techniques. Overall survival was estimated using Kaplan-Meier and Cox proportional hazards models adjusting for patient age, tumor stage and type of treatments. Patients with CXCR4-positive tumors were significantly associated with distant metastasis and tended to have poorer prognosis compared to patients with CXCR4-negative tumors (HR=2.172, 95% CI=1.229‑3.839). No significant association between EGFR expression and survival was found; however co-expression of CXCR4/EGFR was a significant prognostic factor of worse overall survival (HR=2.741, 95% CI=1.330‑5.741). Furthermore, we showed that EGF enhanced the expression of CXCR4 in NSCLC cells through the PI-3K pathway, and treatment of NSCLC cells with EGFR phosphorylation inhibitor, AG1478, resulted in downregulation of the expression of CXCR4. These results suggest an important interaction between CXCR4 and EGFR intra-cellular pathways that may activate signals of tumor progression and may provide a valid explanation for the poor overall survival rate of patients whose co-expression of CXCR4 and EGFR is detected in tissue sections. Based on EGFR and CXCR4 expression, new molecular subtypes of NSCLC established in the present study can be used for customization of NSCLC treatment. Our results also showed that EGFR and CXCR4 are potential therapeutic targets for NSCLC and that simultaneous inhibition of EGFR and CXCR4 in NSCLC patients with concomitant expression of both CXCR4 and EGFR may be an effective treatment strategy.

Nef-M1, a CXCR4 Peptide Antagonist, Enhances Apoptosis and Inhibits Primary Tumor Growth and Metastasis in Breast Cancer

Results from studies with animal models suggest that, in many cancers, CXCR4 is an important therapeutic target and that CXCR4 antagonists may be promising treatments for primary cancers and for metastases. The Nef protein effectively competes with CXCR4’s natural ligand, SDF-1α, and induces apoptosis. As described in this report, the Nef-M1 peptide (Nef protein amino acids 50 – 60) inhibits primary tumor growth and metastasis of breast cancer (BC). Four BC cell lines (MDA-MB-231, MDA-MB-468, MCF 7, and DU4475) and primary human mammary epithelium (HME) cells were evaluated for their response to the Nef protein and to the Nef-M1 peptide. The presence of CXCR4 receptors in these cells was determined by RT-PCR, Western blot (WB), and immunohistochemical analyses. The apoptotic effect of Nef-M1 was assessed by terminal transferase dUTP nick-end labeling (TUNEL). WBs was used to assess caspase 3 activation. BC xenografts grown in SCID mice were evaluated for the presence of CXCR4 and for their metastatic potential. CXCR4 was presented in MDA-MB-231, MCF 7, and DU 4475 BC cells but not in MDA-MB-468 BC or HME cells. Cells expressing CXCR4 and treated with Nef-M1 peptide or the Nef protein had higher rates of apoptosis than untreated cells. Caspase-3 activation increased in MDA-MB 231 cells treated with the Nef protein, the Nef 41 – 60 peptide, or Nef-M1. Nef-M1, administered to mice starting at the time of xenograft implantation, inhibited growth of primary tumors and metastatic spread. Untreated mice developed diffuse intraperitoneal metastases. We conclude that, in BCs, Nef-M1, through interaction with CXCR4, inhibits primary tumor growth and metastasis by causing apoptosis.

Bone metastasis in breast cancer: the story of RANK-ligand

The primary cellular mechanism responsible for osteolytic bone metastases is osteoclastic activation. Preclinical models have shown that breast cancer cells can produce parathyroid hormone-related protein (PTHrP), and other osteolytic molecules, which stimulate excessive osteoclastic bone resorption and establishment of osteolytic lesions. It has been shown that PTHrP by itself cannot directly induce osteoclastic activation, but it mediates its effect through the transactivation of RANK-ligand (RANKL) gene on stromal and osteoblastic cells. Accordingly RANKL up-regulation has been considered as a prerequisite in virtually all conditions of cancer induced bone destruction. Hence, therapeutic targeting of RANKL seems to be a rational approach to treat or even to prevent the process of bone metastases. In this review, we will focus on the unique patho-physiological aspects related to the evolution of bone metastases in breast cancer, emphasizing the pivotal role of RANKL and some other key molecules in osteoclastic bone resorption. We will discuss the therapeutic interventions using bisphosphonates and RANKL inhibitors in patients with bone metastases and the outcome of this novel approach.

Imaging agents for the chemokine receptor 4 (CXCR4)

The interaction between the chemokine receptor 4 (CXCR4) and stromal cell-derived factor-1 (SDF-1, also known as CXCL12) is a natural regulatory process in the human body. However, CXCR4 over-expression is also found in diseases such as cancer, where it plays a role in, among others, the metastatic spread. For this reason it is an interesting biomarker for the field of diagnostic oncology, and therefore, it is gaining increasing interest for applications in molecular imaging. Especially "small-molecule" imaging agents based on T140, FC131 and AMD3100 have been extensively studied. SDF-1, antibodies, pepducins and bioluminescence have also been used to visualize CXCR4. In this critical review reported CXCR4 targeting imaging agents are described based on their affinity, specificity and biodistribution. The level wherein CXCR4 is up-regulated in cancer patients and its relation to the different cell lines and animal models used to evaluate the efficacy of the imaging agents is also discussed (221 references).

C-X-C chemokine receptor 7: a functionally associated molecular marker for bladder cancer

BACKGROUND

C-X-C chemokine receptor 4 (CXCR4) and CXCR7 are 7-transmembrane chemokine receptors of the stroma-derived factor (SDF-1). CXCR4, but not CXCR7, has been examined in bladder cancer (BCa). This study examined the functional and clinical significance of CXCR7 in BCa.

METHODS

CXCR4 and CXCR7 levels were measured in BCa cell lines, tissues (normal = 25; BCa = 44), and urine specimens (n = 186) by quantitative polymerase chain reaction and/or immunohistochemistry. CXCR7 function in BCa cells were examined by transient transfections using a CXCR7 expression vector or small interfering RNA.

RESULTS

In BCa cell lines, CXCR7 messenger RNA levels were 5- to 37-fold higher than those for CXCR4. Transient overexpression of CXCR7 in BCa cell lines promoted growth and chemotactic motility. CXCR7 colocalized and formed a functional complex with epidermal growth factor receptor, phosphoinositide 3-kinase/Akt, Erk, and src and induced their phosphorylation. CXCR7 also induced up-regulation of cyclin-D1 and bcl-2. Suppression of CXCR7 expression reversed these effects and induced apoptosis. CXCR7 messenger RNA levels and CXCR7 staining scores were significantly (5- to 10-fold) higher in BCa tissues than in normal tissues (P < .001). CXCR7 expression independently associated with metastasis (P = .019) and disease-specific mortality (P = .03). CXCR7 was highly expressed in endothelial cells in high-grade BCa tissues when compared to low-grade BCa and normal bladder. CXCR7 levels were elevated in exfoliated urothelial cells from high-grade BCa patients (P = .0001; 90% sensitivity; 75% specificity); CXCR4 levels were unaltered.

CONCLUSIONS

CXCR7 promotes BCa cell proliferation and motility plausibly through epidermal growth factor receptor receptor and Akt signaling. CXCR7 expression is elevated in BCa tissues and exfoliated cells and is associated with high-grade and metastasis.

Systemic treatment of brain metastases in HER2-positive breast cancer: current status and future directions

In recent years, brain metastases have emerged as a main challenge affecting the morbidity and mortality of patients with HER2-positive metastatic breast cancer. In the era following trastuzumab, approximately 30% of these patients develop brain metastases. Trastuzumab does not cross the blood-brain barrier, hence its role is limited to controlling extra-CNS metastases. Lapatinib emerged as a potential candidate; however, its use as a single agent was associated with modest responses. Combination with capecitabine was associated with good results, particularly in patients with newly diagnosed brain metastases. In this article, we discuss the role of trastuzumab and lapatinib in patients with HER2-positive breast cancer with brain metastases. We also highlight the complex structure of the blood-brain barrier and elucidate different potential strategies that could be useful in improving drug delivery.

Bone morphogenetic protein 4 (BMP4) is required for migration and invasion of breast cancer

Bone-morphogenetic proteins (BMPs) play an important role in development and many cellular processes. However, their functional role in the development and progression of breast cancer is not clearly understood. In the present study, we performed a systematic expression analysis of the 14 types of BMPs in 10 human breast cancer cell lines. We found that bone morphogenetic protein 4 (BMP4) was one of the most frequently expressed BMPs. Furthermore, the expression level of BMP4 was maybe correlated with the metastatic potential of the cancer lines. Accordingly, overexpression of BMP4 in the breast cancer cell lines MCF-7 and MBA-MD-231 promoted the migration and invasion phenotypes of the cancer cells, whereas RNAi-mediated knockdown of BMP4 expression inhibited the migration and invasion activities of the cancer cells. To identify the important factors that may mediate the BMP4 functions in breast cancer cells, we analyzed a panel of cancer-related genes, and found that the expression of matrix metalloproteinase-1 (MMP-1) and C-X-C chemokine receptor type 4 (CXCR4) sharply increased at both the mRNA and protein levels in the breast cancer cells overexpressing BMP4. Interestingly, when breast cancer cells MDA-MB-231 or MCF-7 were co-cultured with the osteoblast-like cells MG63 to mimic a bone metastasis microenvironment, BMP4 did not exhibit any significant effect on the expression of OPG or RANKL, two important factors in bone remodeling. BMPs antagonists, Noggin, parallel inhibited breast cancer cell migration and invasion and induced bone remodeling. Taken together, our results strongly suggest that BMP4 may promote the migration and invasion of breast cancer cells, at least in part by up-regulating the expressions of MMP-1 and CXCR4. It is conceivable that novel therapeutics for breast cancer may be developed by targeting BMP4 signaling pathway and/or its important downstream mediators in breast cancer cells.

Loss of interferon regulatory factor 5 (IRF5) expression in human ductal carcinoma correlates with disease stage and contributes to metastasis

INTRODUCTION

New signaling pathways of the interleukin (IL) family, interferons (IFN) and interferon regulatory factors (IRF) have recently been found within tumor microenvironments and in metastatic sites. Some of these cytokines stimulate while others inhibit breast cancer proliferation and/or invasion. IRFs, a family of nine mammalian transcription factors, have multiple biologic functions that when dysregulated may contribute to tumorigenesis; most well-known are their roles in regulating/initiating host immunity. Some IRF family members have been implicated in tumorigenesis yet little is still known of their expression in primary human tumors or their role(s) in disease development/progression. IRF5 is one of the newer family members to be studied and has been shown to be a critical mediator of host immunity and the cellular response to DNA damage. Here, we examined the expression of IRF5 in primary breast tissue and determined how loss of expression may contribute to breast cancer development and/or progression.

METHODS

Formalin-fixed paraffin-embedded archival breast tissue specimens from patients with atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) were examined for their expression of IRF1 and IRF5. Knockdown or overexpression of IRF5 in MCF-10A, MCF-7 and MDA-MB-231 mammary epithelial cell lines was used to examine the role of IRF5 in growth inhibition, invasion and tumorigenesis.

RESULTS

Analysis of IRF expression in human breast tissues revealed the unique down-regulation of IRF5 in patients with different grades of DCIS and IDC as compared to IRF1; loss of IRF5 preceded that of IRF1 and correlated with increased invasiveness. Overexpression of IRF5 in breast cancer cells inhibited in vitro and in vivo cell growth and sensitized them to DNA damage. Complementary experiments with IRF5 siRNAs made normal mammary epithelial cells resistant to DNA damage. By 3-D culture, IRF5 overexpression reverted MDA-MB-231 to normal acini-like structures; cells overexpressing IRF5 had decreased CXCR4 expression and were insensitive to SDF-1/CXCL12-induced migration. These findings were confirmed by CXCR4 promoter reporter assays.

CONCLUSIONS

IRF5 is an important tumor suppressor that regulates multiple cellular processes involved in the conversion of normal mammary epithelial cells to tumor epithelial cells with metastatic potential.

Breast cancer - one term, many entities?

Breast cancer, rather than constituting a monolithic entity, comprises heterogeneous tumors with different clinical characteristics, disease courses, and responses to specific treatments. Tumor-intrinsic features, including classical histological and immunopathological classifications as well as more recently described molecular subtypes, separate breast tumors into multiple groups. Tumor-extrinsic features, including microenvironmental configuration, also have prognostic significance and further expand the list of tumor-defining variables. A better understanding of the features underlying heterogeneity, as well as of the mechanisms and consequences of their interactions, is essential to improve targeting of existing therapies and to develop novel agents addressing specific combinations of features.

Stem Cell Transplantation for Hematological Malignancies: Prospects for Personalized Medicine and Co-therapy with Mesenchymal Stem Cells

Bone marrow transplantation is a form of cell therapy that has been in practice for decades for the treatment of hematological disorders and solid tumors. Immunosuppressive therapy has been a mainstay for treatment, but the severity of the adverse effects has made it an undesirable choice. Mesenchymal stem cells (MSCs), which reside in the vascular regions of the bone marrow, have been shown to serve as cellular support for the hematopoietic stem cell (HSC) niche. Furthermore, the immune suppressive properties of MSCs have been explored in the treatment of inflammatory and autoimmune disorders. Thus, co-therapy with MSCs has been shown to facilitate engraftment of hematopoietic cells by suppressive graft versus host disease (GvHD). Although the mechanism by which MSCs suppress GvHD is unclear, the experimental evidence suggests that this partly occurs by modulation of immune response such as the induction of regulatory T cells. This paper discusses the role of MSCs as co-therapy for the future of stem cell transplantation, with the overarching theme of personalized medicine for cell-based health interventions.

Immunohistochemical detection of the CXCR4 expression in tumor tissue using the fluorescent peptide antagonist Ac-TZ14011-FITC

Pathology is fundamental in grading, staging, and treatment planning of malignancies. One relatively novel biomarker that may become more important in therapy and diagnostics is the chemokine receptor 4 (CXCR4). Ac-TZ14011 peptide derivatives, functionalized with a radiolabel, can be used for molecular imaging of tumors. Direct fluorescent labeling of the small peptide Ac-TZ14011 with the fluorescent dye fluorescein isothiocyanate (FITC), however, provides an alternative for the detection of CXCR4 expression levels in cells and tumor tissue. In this study, Ac-TZ14011-FITC was validated for CXCR4 staining in human breast cancer cell lines MDAMB231 and MDAMB231(CXCR4+) during flow cytometric analysis. Its efficacy was compared to commercially available antibodies. Competition experiments validated the staining specificity. Confocal imaging revealed that CXCR4 staining was predominantly found on the cell membrane and/or in vesicles formed after endocytosis. Next to being able to differentiate "high" and "low" CXCR4-expressing tumor cells, the fluorescent peptide demonstrates potential in fluorescent immunohistochemistry of tumor tissue. Ac-TZ14011-FITC was able to differentiate MDAMB231 from MDAMB231(CXCR4+) tumor cells and tissue, proving its applicability in the detection of differences in CXCR4 expression levels.

Role of RANK, RANKL, OPG, and CXCR4 tissue markers in predicting bone metastases in breast cancer patients

This is a retrospective study on 40 breast cancer patients, of which 20 have bone metastases, 10 have visceral metastases, and 10 have no evidence of disease, aimed at evaluating the role of CXCR4 and the RANK/RANKL/OPG system to predict bone metastases. CXCR4 expression, alone or in combination with RANK, identified patients destined to relapse to bone.

BACKGROUND

The RANK/RANKL/OPG system is active in primary cancers such as breast, prostate, and also in their bone metastases. CXCR4 chemokine receptor is highly expressed in human breast cancer cells and is believed to facilitate the homing of tumor cells to organs such as bone that express high levels of its ligand SDF1. Our study aimed to investigate whether the analysis of these markers with an inexpensive and simple test can help to predict bone metastases in breast cancer patients.

PATIENTS AND METHODS

Marker expression was evaluated by immunohistochemical staining in paraffin-embedded tissue sections of primary breast cancers from 40 individuals: 20 patients with bone metastases (BM), 10 with visceral metastases (VM; considered together as the relapsed group), and 10 with no evidence of disease (NED).

RESULTS

RANKL was not detected in tumor cells. OPG- and RANK-positive tumors are found with similar frequency in NED (20%) and in relapsed patients (23% and 17%, respectively). However, in the latter subgroup, only RANK positivity was always associated with bone relapse. The frequency of CXCR4-positive tumors was three-fold higher in relapsed (30%) than in NED (10%) patients and positivity was always linked to bone metastases. Considering NED and VM patients together versus BM patients, we observed that CXCR4 expression, alone (P = .008) or in combination with RANK (P < .001), identified patients destined to relapse to bone.

CONCLUSION

Our results provide the first clinical evidence to support a pivotal role of combined CXCR4 and RANK expression in predicting bone relapse.