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

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.

TNF-Related Apoptosis-Inducing Ligand: Non-Apoptotic Signalling

TNF-related apoptosis-inducing ligand (TRAIL or Apo2 or TNFSF10) belongs to the TNF superfamily. When bound to its agonistic receptors, TRAIL can induce apoptosis in tumour cells, while sparing healthy cells. Over the last three decades, this tumour selectivity has prompted many studies aiming at evaluating the anti-tumoral potential of TRAIL or its derivatives. Although most of these attempts have failed, so far, novel formulations are still being evaluated. However, emerging evidence indicates that TRAIL can also trigger a non-canonical signal transduction pathway that is likely to be detrimental for its use in oncology. Likewise, an increasing number of studies suggest that in some circumstances TRAIL can induce, via Death receptor 5 (DR5), tumour cell motility, potentially leading to and contributing to tumour metastasis. While the pro-apoptotic signal transduction machinery of TRAIL is well known from a mechanistic point of view, that of the non-canonical pathway is less understood. In this study, we the current state of knowledge of TRAIL non-canonical signalling.

Evaluation of immune density, PD-L1, and CXCR4 expressions in metaplastic breast carcinoma to predict potential immunotherapy benefit

Metaplastic breast carcinoma (MBC) -rare but fatal subtype of invasive breast carcinomas- provides limited benefit from conventional triple-negative breast carcinoma chemotherapy. We aimed to determine the immune density of this tumor and to evaluate of programmed death-ligand 1 (PD-L1) and chemokine receptor type 4 (CXCR4) expressions to determine whether it would benefit from immunotherapy. Clinicopathological characteristics of 85 patients diagnosed as MBC between 1997 and 2017 were retrospectively assessed. We evaluated the immunohistochemical expression of PD-L1 and CXCR4, and the extent of tumour infiltrating lymphocytes (TILs), with survival data. TILs groups were statistically significantly associated with lymph node status, histological subtype, squamous component, local recurrence and/or systemic metastasis, and disease-related deaths (p < 0.05). PD-L1 positivity in immune cells (ICs) has a statistically significant relationship with the presence of squamous component (p = 0.011) and HER2 positivity (p = 0.031). PD-L1 positivity in tumor cells (TCs) was found to be significantly more frequent in high-TILs density (p = 0.003). PD-L1 combined positive score was significantly associated with the tumors containing high-TILs density (p = 0.012) and squamous component (p = 0.035). Disease-free and disease-specific survival rates were found to be longer for the cases displaying PD-L1 positivity in ICs; and also PD-L1 positivity in ICs was found to be an independent prognostic factor. When the expression of CXCR4 was compared with clinicopathological and survival parameters, no statistically significant association was found (p > 0.05). Based on the results of this retrospective study, PD-L1 and TILs appear to be prognostic. This study provides rationale for further studies to determine whether a subset of patients with metaplastic breast cancer could derive a meaningful benefit from immune-targeting therapies.

Forkhead Box Q1 is a novel regulator of autophagy in breast cancer cells

Forkhead Box Q1 (FoxQ1) transcription factor is overexpressed in luminal-type and basal-type human breast cancers when compared to normal mammary tissue. This transcription factor is best known for its role in promotion of breast cancer stem-like cells and epithelial to mesenchymal transition. The present study documents a novel function of FoxQ1 in breast cancer cells. Overexpression of FoxQ1 in basal-like SUM159 cells and luminal-type MCF-7 cells resulted in increased conversion of microtubule-associated protein light chain 3 beta-I (LC3B-I) to LC3B-II, which is a hallmark of autophagy. Autophagy induction by FoxQ1 overexpression was confirmed by visualization of LC3B puncta as well as by transmission electron microscopy. Expression profiling for genes implicated in autophagy regulation revealed upregulation of many genes, including ATG4B, ATG16L1, CTSS, CXCR4 and so forth but downregulation of BCL2L1, DRAM1, TNF, ULK2 and so forth by FoxQ1 overexpression in SUM159 cells. Western blot analysis confirmed upregulation of ATG4B and CXCR4 proteins by FoxQ1 overexpression in both SUM159 and MCF-7 cells. Chromatin immunoprecipitation assay revealed recruitment of FoxQ1 at the promoter of ATG4B. Pharmacological inhibition of ATG4B using S130 significantly increased apoptosis induction by DOX in empty vector transfected as well as FoxQ1 overexpressing SUM159 and MCF-7 cells but this effect was statistically significantly lowered by FoxQ1 overexpression indicating the protective role of FoxQ1 on apoptosis. Treatment of SUM159 cells with S130 and DOX enhanced LC3B-II level in both empty vector transfected cells and FoxQ1 overexpressing SUM159 cells but not in FoxQ1 overexpressing MCF-7 cells. In conclusion, FoxQ1 is a novel regulator of autophagy.

Inhibition of Dipeptidyl Peptidase-4 Activates Autophagy to Promote Survival of Breast Cancer Cells via the mTOR/HIF-1α Pathway

Autophagy plays a complex role in breast cancer cell survival, metastasis, and chemotherapeutic resistance. Dipeptidyl peptidase (DPP)-4, a therapeutic target for type 2 diabetes mellitus, is also involved in autophagic flux. The potential influence of DPP-4 suppression on cancer biology remains unknown. Here, we report that DPP-4 deficiency promotes breast cancer cell survival via the induction of autophagy by the C-X-C motif chemokine 12 (CXCL12)/C-X-C receptor 4 (CXCR4)/mammalian target of rapamycin (mTOR)/hypoxia inducible factor (HIF)-1α axis. DPP-4 knockdown and DPP-4 inhibitor KR62436 (KR) treatment both increased the levels of LC3II and HIF-1α in cultured human breast and mouse mammary cancer cells. The KR-induced autophagic phenotype in cancer cells was inhibited by treatment with the CXCR4 inhibitor AMD3100 and rapamycin. HIF-1α knockdown also suppressed breast cancer autophagy induced by KR. The autophagy inhibitor 3-methyladenine significantly blocked the KR-mediated suppression of cleaved caspase-3 levels and apoptosis in breast cancer cell lines. Finally, we found that the metformin-induced apoptosis of DPP-4-deficient 4T1 mammary cancer cells was associated with the suppression of autophagy. Our findings identify a novel role for DPP-4 inhibition in the promotion of breast cancer survival by inducing CXCL12/CXCR4/mTOR/HIF-1α axis-dependent autophagy. Metformin is a potential drug that counteracts the breast cancer cell survival system.

Molecular signaling network and therapeutic developments in breast cancer brain metastasis

Breast cancer (BC) is one of the most frequently diagnosed cancers in women worldwide. It has surpassed lung cancer as the leading cause of cancer-related death. Breast cancer brain metastasis (BCBM) is becoming a major clinical concern that is commonly associated with ER-ve and HER2+ve subtypes of BC patients. Metastatic lesions in the brain originate when the cancer cells detach from a primary breast tumor and establish metastatic lesions and infiltrate near and distant organs via systemic blood circulation by traversing the BBB. The colonization of BC cells in the brain involves a complex interplay in the tumor microenvironment (TME), metastatic cells, and brain cells like endothelial cells, microglia, and astrocytes. BCBM is a significant cause of morbidity and mortality and presents a challenge to developing successful cancer therapy. In this review, we discuss the molecular mechanism of BCBM and novel therapeutic strategies for patients with brain metastatic BC.

Luminescent Quantum Dots: Synthesis, Optical Properties, Bioimaging and Toxicity

Luminescent nanomaterials such as semiconductor nanocrystals (NCs) and quantum dots (QDs) attract much attention to optical detectors, LEDs, photovoltaics, displays, biosensing, and bioimaging. These materials include metal chalcogenide QDs and metal halide perovskite NCs. Since the introduction of cadmium chalcogenide QDs to biolabeling and bioimaging, various metal nanoparticles (NPs), atomically precise metal nanoclusters, carbon QDs, graphene QDs, silicon QDs, and other chalcogenide QDs have been infiltrating the nano-bio interface as imaging and therapeutic agents. Nanobioconjugates prepared from luminescent QDs form a new class of imaging probes for cellular and in vivo imaging with single-molecule, super-resolution, and 3D resolutions. Surface modified and bioconjugated core-only and core-shell QDs of metal chalcogenides (MX; M = Cd/Pb/Hg/Ag, and X = S/Se/Te,), binary metal chalcogenides (MInX₂; M = Cu/Ag, and X = S/Se/Te), indium compounds (InAs and InP), metal NPs (Ag, Au, and Pt), pure or mixed precision nanoclusters (Ag, Au, Pt), carbon nanomaterials (graphene QDs, graphene nanosheets, carbon NPs, and nanodiamond), silica NPs, silicon QDs, etc. have become prevalent in biosensing, bioimaging, and phototherapy. While heavy metal-based QDs are limited to in vitro bioanalysis or clinical testing due to their potential metal ion-induced toxicity, carbon (nanodiamond and graphene) and silicon QDs, gold and silica nanoparticles, and metal nanoclusters continue their in vivo voyage towards clinical imaging and therapeutic applications. This review summarizes the synthesis, chemical modifications, optical properties, and bioimaging applications of semiconductor QDs with particular references to metal chalcogenide QDs and bimetallic chalcogenide QDs. Also, this review highlights the toxicity and pharmacokinetics of QD bioconjugates.

Comprehensive analysis of the immunological implication and prognostic value of CXCR4 in non-small cell lung cancer

CXCR4 (C-X-C chemokine receptor type 4) is the most commonly expressed of all chemokine receptors in malignant tumors. However, studies on CXCR4 in non-small cell lung cancer (NSCLC) tumor immune microenvironment, including those determining its immune efficacy and prognostic potential, are still scarce. Therefore, in this study, we determined the ability of CXCR4 to predict immunotherapy response and prognosis in NSCLC using immunohistochemical staining and RT-PCR, respectively, in two independent cohorts from the National Cancer Center of China. We analyzed transcriptome sequencing data and clinical information from multiple public databases to assess immune cell infiltration in NSCLC and constructed immune risk prognostic signatures based on CXCR4-related immunomodulators. We found that immune cell infiltration is significant differences in NSCLC tissues and is moderately correlated with CXCR4 expression. High CXCR4 expression was significantly associated with poor prognosis in NSCLC patients and a higher response rate to immunotherapy. The ROC curve showed that CXCR4 expression exhibited excellent performance in predicting the efficacy of immunotherapy in NSCLC. We identified 30 CXCR4-related immunomodulators in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) and constructed immune prognostic signatures based on CXCR4-related immunomodulators and CXCR4-related mutant genes. The signature-based prognostic risk score showed good performance in predicting patient prognosis in both LUAD and LUSC; high risk scores were significantly associated with poor prognosis (P < 0.0001) and was established as an independent prognostic factor by multivariate Cox regression. We postulate that CXCR4 is a potential predictive marker of immunotherapy efficacy in NSCLC and should be used in clinical settings. Moreover, the constructed signatures may be valuable in predicting patient prognosis in NSCLC.

CD1C is associated with breast cancer prognosis and immune infiltrates

BACKGROUND

The tumor microenvironment (TME) in breast cancer plays a vital role in occurrence, development, and therapeutic responses. However, immune and stroma constituents in the TME are major obstacles to understanding and treating breast cancer. We evaluated the significance of TME-related genes in breast cancer.

METHODS

Invasive breast cancer (BRCA) samples were retrieved from the TCGA and GEO databases. Stroma and immune scores of samples as well as the proportion of tumor infiltrating immune cells (TICs) were calculated using the ESTIMATE and CIBERSORT algorithms. TME-related differentially expressed genes (DEGs) were analyzed by a protein interaction (PPI) network and univariate Cox regression to determine CD1C as a hub gene. Subsequently, the prognostic value of CD1C, its response to immunotherapy, and its mechanism in the TME were further studied.

RESULTS

In BRCA, DEGs were determined to identify CD1C as a hub gene. The expression level of CD1C in BRCA patients was verified based on the TCGA database, polymerase chain reaction (PCR) results, and western blot analysis. Immunohistochemical staining (IHC) results revealed a correlation between prognosis, clinical features, and CD1C expression in BRCA. Enrichment analysis of GSEA and GSVA showed that CD1C participates in immune-associated signaling pathways. CIBERSORT showed that CD1C levels were associated with tumor immune infiltrating cells (TILs), such as different kinds of T cells. Gene co-expression analysis showed that CD1C and the majority of immune-associated genes were co-expressed in BRCA. In renal cell carcinoma, patients with a high expression of CD1C had a better immunotherapy effect.

CONCLUSION

CD1C is an important part of the TME and participates in immune activity regulation in breast tumors. CD1C is expected to become a prognostic marker and a new treatment target for breast cancer.

Current Status of 68Ga-Pentixafor in Solid Tumours

Chemokine receptor CXCR4 is overexpressed in neoplasms and its expression is related to tumour invasion, metastasis and aggressiveness. ⁶⁸Ga-Pentixafor is used to non-invasively image the expression of CXCR4 in tumours and has been widely used in haematological malignancies. Recent evidence shows that therapies targeting CXCR4 can increase the chemosensitivity of the tumour as well as inhibit tumour metastasis and aggressiveness. ⁶⁸Ga-Pentixafor has shown promise as an elegant radiotracer to aid in the selection of patients whose tumours demonstrate CXCR4 overexpression and who therefore may benefit from novel therapies targeting CXCR4. In addition, its therapeutic partners ¹⁷⁷Lu- and ⁹⁰Y-Pentixather have been investigated in the treatment of patients with advanced haematological malignancies, and initial studies have shown a good treatment response in metabolically active lesions. ⁶⁸Ga-Pentixafor in solid tumours complements ¹⁸F-FDG by providing prognostic information and selecting patients who may benefit from therapies targeting CXCR4. This review summarises the available literature on the potential applications of ⁶⁸Ga-Pentixafor in solid tumours.

The potential effects and mechanisms of breast inflammatory lesions on the occurrence and development of breast cancer

Breast cancer as the most common cancer in women has become the leading cause of cancer death for women. Although many inflammatory factors increase the risk of breast cancer, there are very few studies on the mechanisms by which inflammation affects the initiation and progression of breast cancer. Here, we profiled and compared the transcriptome of normal tissues, inflammatory breast tissues, benign breast tumors, and malignant breast tumors. To find key regulatory factors, a protein interaction network between characteristic modules in inflammatory lesions and ER-negative (ER⁻) breast cancer was constructed and inflammation-cancer interface genes were identified. We found that the transcriptional profile of inflammatory breast tissues was similar with ER⁻ malignant tumors, featured with low ER expression levels and similar immune signaling pathway activation. Through comprehensive protein network analysis, we identified the interface genes and chemokine signaling pathway that have the potential to promote inflammatory cancer transformation. These interface genes could be used as a risk factor to provide a certain basis for the clinical early detection and treatment of breast cancer. This is the first study to explore the association between breast inflammatory lesions and breast cancer at the transcriptome level. Our inflammation data and research results provide a basis for future inflammation-cancer transformation analysis.

Metformin counteracts stimulatory effects induced by insulin in primary breast cancer cells

Background

Metabolic disorders are associated with increased incidence, aggressive phenotype and poor outcome of breast cancer (BC) patients. For instance, hyperinsulinemia is an independent risk factor for BC and the insulin/insulin receptor (IR) axis is involved in BC growth and metastasis. Of note, the anti-diabetic metformin may be considered in comprehensive therapeutic approaches in BC on the basis of its antiproliferative effects obtained in diverse pre-clinical and clinical studies.

Methods

Bioinformatics analysis were performed using the information provided by The Invasive Breast Cancer Cohort of The Cancer Genome Atlas (TCGA) project. The naturally immortalized BC cell line, named BCAHC-1, as well as cancer-associated fibroblasts (CAFs) derived from BC patients were used as model systems. In order to identify further mechanisms that characterize the anticancer action of metformin in BC, we performed gene expression and promoter studies as well as western blotting experiments. Moreover, cell cycle analysis, colony and spheroid formation, actin cytoskeleton reorganization, cell migration and matrigel drops evasion assays were carried out to provide novel insights on the anticancer properties of metformin.

Results

We first assessed that elevated expression and activation of IR correlate with a worse prognostic outcome in estrogen receptor (ER)-positive BC. Thereafter, we established that metformin inhibits the insulin/IR-mediated activation of transduction pathways, gene changes and proliferative responses in BCAHC-1 cells. Then, we found that metformin interferes with the insulin-induced expression of the metastatic gene CXC chemokine receptor 4 (CXCR4), which we found to be associated with poor disease-free survival in BC patients exhibiting high levels of IR. Next, we ascertained that metformin prevents a motile phenotype of BCAHC-1 cells triggered by the paracrine liaison between tumor cells and CAFs upon insulin activated CXCL12/CXCR4 axis.

Conclusions

Our findings provide novel mechanistic insights regarding the anti-proliferative and anti-migratory effects of metformin in both BC cells and important components of the tumor microenvironment like CAFs. Further investigations are warranted to corroborate the anticancer action of metformin on the tumor mass toward the assessment of more comprehensive strategies halting BC progression, in particular in patients exhibiting metabolic disorders and altered insulin/IR functions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03463-y.

Characteristics of immunophenotypes and immunological in tumor microenvironment and analysis of immune implication of CXCR4 in gastric cancer

The formation of gastric cancer (GC) is a complicated process involving multiple factors and multiple steps. The tumor–immune microenvironment is essential for the growth of GC and affects the prognosis of patients. We performed multiple machine learning algorithms to identify immunophenotypes and immunological characteristics in GC patients’ information from the TCGA database and extracted immune genes relevance of the GC immune microenvironment. C-X-C motif chemokine receptor 4 (CXCR4), belongs to the C-X-C chemokine receptor family, which can promote the invasion and migration of tumor cells. CXCR4 expression is significantly correlated to metastasis and the worse prognosis. In this work, we assessed the condition of immune cells and identified the connection between CXCR4 and GC immune microenvironment, as well as the signaling pathways that mediate the immune responses involved in CXCR4. The work showed the risk scores generated by CXCR4-related immunomodulators could distinguish risk groups consisting of differential expression genes and could use for the personalized prognosis prediction. The findings suggested that CXCR4 is involved in tumor immunity of GC, and CXCR4 is considered as a potential prognostic biomarker and immunotherapy target of GC. The prognostic immune markers from CXCR4-associated immunomodulators can independently predict the overall survival of GC.

An Evaluation of CXCR4 Targeting with PAMAM Dendrimer Conjugates for Oncologic Applications

The chemokine receptor 4 (CXCR4) is a promising diagnostic and therapeutic target for the management of various cancers. CXCR4 has been utilized in immunotherapy, targeted drug delivery, and endoradiotherapy. Poly(amidoamine) [PAMAM] dendrimers are well-defined polymers with unique properties that have been used in the fabrication of nanomaterials for several biomedical applications. Here, we describe the formulation and pharmacokinetics of generation-5 CXCR4-targeted PAMAM (G5-X4) dendrimers. G5-X4 demonstrated an IC₅₀ of 0.95 nM to CXCR4 against CXCL12-Red in CHO-SNAP-CXCR4 cells. Single-photon computed tomography/computed tomography imaging and biodistribution studies of ¹¹¹In-labeled G5-X4 showed enhanced uptake in subcutaneous U87 glioblastoma tumors stably expressing CXCR4 with 8.2 ± 2.1, 8.4 ± 0.5, 11.5 ± 0.9, 10.4 ± 2.6, and 8.8 ± 0.5% injected dose per gram of tissue at 1, 3, 24, 48, and 120 h after injection, respectively. Specific accumulation of [¹¹¹In]G5-X4 in CXCR4-positive tumors was inhibited by the peptidomimetic CXCR4 inhibitor, POL3026. Our results demonstrate that while CXCR4 targeting is beneficial for tumor accumulation at early time points, differences in tumor uptake are diminished over time as passive accumulation takes place. This study further confirms the applicability of PAMAM dendrimers for imaging and therapeutic applications. It also emphasizes careful consideration of image acquisition and/or treatment times when designing dendritic nanoplatforms for tumor targeting.

Antibacterial Activity of T22, a Specific Peptidic Ligand of the Tumoral Marker CXCR4

CXCR4 is a cytokine receptor used by HIV during cell attachment and infection. Overexpressed in the cancer stem cells of more than 20 human neoplasias, CXCR4 is a convenient antitumoral drug target. T22 is a polyphemusin-derived peptide and an effective CXCR4 ligand. Its highly selective CXCR4 binding can be exploited as an agent for the cell-targeted delivery and internalization of associated antitumor drugs. Sharing chemical and structural traits with antimicrobial peptides (AMPs), the capability of T22 as an antibacterial agent remains unexplored. Here, we have detected T22-associated antimicrobial activity and biofilm formation inhibition over Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, in a spectrum broader than the reference AMP GWH1. In contrast to GWH1, T22 shows neither cytotoxicity over mammalian cells nor hemolytic activity and is active when displayed on protein-only nanoparticles through genetic fusion. Under the pushing need for novel antimicrobial agents, the discovery of T22 as an AMP is particularly appealing, not only as its mere addition to the expanding catalogue of antibacterial drugs. The recognized clinical uses of T22 might allow its combined and multivalent application in complex clinical conditions, such as colorectal cancer, that might benefit from the synchronous destruction of cancer stem cells and local bacterial biofilms.

Recurrence biomarkers of triple negative breast cancer treated with neoadjuvant chemotherapy and anti-EGFR antibodies

To find metastatic recurrence biomarkers of triple-negative breast cancer (TNBC) treated by neoadjuvant chemotherapy and anti-EGFR antibodies (NAT), we evaluated tumor genomic, transcriptomic, and immune features, using MSK-IMPACT assay, gene arrays, Nanostring technology, and TIL assessment on H&E. Six patients experienced a rapid fatal recurrence (RR) and other 6 had later non-fatal recurrences (LR). Before NAT, RR had low expression of 6 MHC class I and 13 MHC class II genes but were enriched in upregulated genes involved in the cell cycle-related pathways. Their TIL number before NAT in RR was very low (<5%) and did not increase after treatment. In post-NAT residual tumors, RR cases showed high expression of SOX2 and CXCR4. Our results indicate that high expression of cell cycle genes, combined with cold immunological phenotype, may predict strong TNBC resistance to NAT and rapid progression after it. This biomarker combination is worth validation in larger studies.

Prognostic Significance of CXCR4 in Colorectal Cancer: An Updated Meta-Analysis and Critical Appraisal

Simple Summary

C-X-C chemokine receptor type 4 (CXCR4), a G-protein-coupled receptor, has been demonstrated to stimulate proliferation and invasiveness of many different tumors, including colorectal cancer. Through in vitro evidence, overexpression of CXCR4 has been identified as a negative prognostic factor in colorectal cancer. The identification of prognostic biomarkers can improve the prediction of disease evolution and disease characterization, and guide treatment efforts. This systematic review with a meta-analysis was conducted to pool hazard ratios from prognostic studies on CXCR4, provide an updated estimate of prognostic power of CXCR4, and analyze modalities of evaluating and reporting CXCR4 expression.

Abstract

Background: This study was conducted to provide an updated estimate of the prognostic power of C-X-C chemokine receptor type 4 (CXCR4) in colorectal cancer (CRC), and analyze modalities of evaluating and reporting its expression. Methods: A systematic review with meta-analysis was performed and described according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Studies were identified through PubMed and Google Scholar. The pooled hazard ratios (HRs) for overall survival (OS) or progression-free survival (PFS) with 95% confidence interval (CI) were estimated with the random-effect model. Results: Sixteen studies were selected covering a period from 2005 to 2020. An immunohistochemical evaluation of CXCR4 was performed in all studies. Only in three studies assessment of mRNA through RT–PCR was correlated with prognosis; in the remaining studies, the authors identified prognostic categories based on immunohistochemical expression. In pooled analyses, significant associations were found between positive or high or strong expression of CXCR4 and T stage ≥3 (P = 0.0001), and positive or high or strong expression of CXCR4 and left side primary tumor localization (P = 0.0186). The pooled HR for OS was 2.09 (95% CI: 1.30–2.88) in favor of high CXCR4 expression; for PFS, it was 1.42 (95% CI: 1.13–1.71) in favor of high CXCR4 expression. Conclusion: High CXCR4 expression is clearly associated with increased risk of death and progression in CRC. However, strong methodologic heterogeneity in CXCR4 assessment hinders direct translation into clinical practice; thus, a consensus to streamline detection and scoring of CXCR4 expression in CRC is indicated.

Pathogenesis and Potential Therapeutic Targets for Triple-Negative Breast Cancer

Triple negative breast cancer (TNBC) is a heterogeneous tumor characterized by early recurrence, high invasion, and poor prognosis. Currently, its treatment includes chemotherapy, which shows a suboptimal efficacy. However, with the increasing studies on TNBC subtypes and tumor molecular biology, great progress has been made in targeted therapy for TNBC. The new developments in the treatment of breast cancer include targeted therapy, which has the advantages of accurate positioning, high efficiency, and low toxicity, as compared to surgery, radiotherapy, and chemotherapy. Given its importance as cancer treatment, we review the latest research on the subtypes of TNBC and relevant targeted therapies.

Role of krüppel-like factor 8 for therapeutic drug-resistant multi-organ metastasis of breast cancer

Metastasis and drug resistance are intertwined processes that are responsible for the vast majority of patient deaths from breast cancer. The underlying mechanisms remain incompletely understood. We previously demonstrated that KLF8 activates CXCR4 transcription in metastatic breast cancer. Here, we report a novel role of KLF8-CXCR4 signaling for converting single organ metastasis into multiple organ metastasis associated with chemotherapeutic resistance. We show that KLF8 expression in metastatic breast cancer cells can be over-induced by chemotherapeutic drugs. Analysis of data from large-cohorts of patients indicates that post-chemotherapy there is a close correlation between the aberrant high levels of KLF8 and CXCR4 and that this correlation is well associated with drug resistance, metastasis, and poor prognosis. To mimic their aberrant high levels, we overexpressed KLF8 or CXCR4 in a human breast cancer cell line known to metastasize only to the lungs after intravenous injection in nude mice. As expected, these cells become more resistant to chemotherapeutic drugs. Surprisingly, these KLF8 or CXCR4 overexpressing cells, even implanted orthotopically, metastasized extensively to multiple organs particularly the CXCL12-rich organs. Tube formation assay, Ki67 staining and Western blotting revealed that KLF8 or CXCR4 overexpression enhanced angiogenesis involving increased expression and secretion of VEGF protein. We also found that KLF8 or CXCR4 overexpression strongly enhanced formation of filopodium-like protrusions and proliferation via CXCR4 stimulation in a 3D culture model mimicking the colonization step of metastasis. Taken together, these results suggest that the chemo-induction of KLF8 upregulation be critical for drug resistance and systemic metastasis through enhanced tumor angiogenesis and colonization via CXCR4 over-activation and that KLF8-CXCR4 signaling axis may be a new therapeutic target for drug-resistant breast cancer metastasis.

Loss of Cxcr4 in Endometriosis Reduces Proliferation and Lesion Number while Increasing Intraepithelial Lymphocyte Infiltration

Hyperactivation of the CXCL12-CXCR4 axis occurs in endometriosis; the therapeutic potential of treatments aimed at global inhibition of the axis was recently reported. Because CXCR4 is predominantly expressed on epithelial cells in the uterus, this study explored the effects of targeted disruption of CXCR4 in endometriosis lesions. Uteri derived from adult female mice homozygous for a floxed allele of CXCR4 and co-expressing Cre recombinase under control of progesterone receptor promoter were sutured onto the peritoneum of cycling host mice expressing the green fluorescent protein. Four weeks after endometriosis induction, significantly lower number of lesions developed in Cxcr4-conditional knockout lesions relative to those in controls (37.5% vs. 68.8%, respectively). In lesions that developed in Cxcr4-knockout, reduced epithelial proliferation was associated with a lower ratio of epithelial to total lesion area compared with controls. Furthermore, while CD3⁺ lymphocytes were largely excluded from the epithelial compartment in control lesions, in Cxcr4-knockout lesions, CD3⁺ lymphocytes infiltrated the Cxcr4-deficient epithelium in the diestrus and proestrus stages. Current data demonstrate that local CXCR4 expression is necessary for proliferation of the epithelial compartment of endometriosis lesions, that its downregulation compromises lesion numbers, and suggest a role for epithelial CXCR4 in lesion immune evasion.

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.

Preclinical Advances in Theranostics for the Different Molecular Subtypes of Breast Cancer

Breast cancer is the most common cancer in women worldwide. The heterogeneity of breast cancer and drug resistance to therapies make the diagnosis and treatment difficult. Molecular imaging methods with positron emission tomography (PET) and single-photon emission tomography (SPECT) provide useful tools to diagnose, predict, and monitor the response of therapy, contributing to precision medicine for breast cancer patients. Recently, many efforts have been made to find new targets for breast cancer therapy to overcome resistance to standard of care treatments, giving rise to new therapeutic agents to offer more options for patients with breast cancer. The combination of diagnostic and therapeutic strategies forms the foundation of theranostics. Some of these theranostic agents exhibit high potential to be translated to clinic. In this review, we highlight the most recent advances in theranostics of the different molecular subtypes of breast cancer in preclinical studies.

Nonreplicating Adenoviral Vectors: Improving Tropism and Delivery of Cancer Gene Therapy

Recent preclinical and clinical studies have used viral vectors in gene therapy research, especially nonreplicating adenovirus encoding strategic therapeutic genes for cancer treatment. Adenoviruses were the first DNA viruses to go into therapeutic development, mainly due to well-known biological features: stability in vivo, ease of manufacture, and efficient gene delivery to dividing and nondividing cells. However, there are some limitations for gene therapy using adenoviral vectors, such as nonspecific transduction of normal cells and liver sequestration and neutralization by antibodies, especially when administered systemically. On the other hand, adenoviral vectors are amenable to strategies for the modification of their biological structures, including genetic manipulation of viral proteins, pseudotyping, and conjugation with polymers or biological membranes. Such modifications provide greater specificity to the target cell and better safety in systemic administration; thus, a reduction of antiviral host responses would favor the use of adenoviral vectors in cancer immunotherapy. In this review, we describe the structural and molecular features of nonreplicating adenoviral vectors, the current limitations to their use, and strategies to modify adenoviral tropism, highlighting the approaches that may allow for the systemic administration of gene therapy.

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.

Design and engineering of tumor-targeted, dual-acting cytotoxic nanoparticles

The possibility to conjugate tumor-targeted cytotoxic nanoparticles and conventional antitumoral drugs in single pharmacological entities would open a wide spectrum of opportunities in nanomedical oncology. This principle has been explored here by using CXCR4-targeted self-assembling protein nanoparticles based on two potent microbial toxins, the exotoxin A from Pseudomonas aeruginosa and the diphtheria toxin from Corynebacterium diphtheriae, to which oligo-floxuridine and monomethyl auristatin E respectively have been chemically coupled. The resulting multifunctional hybrid nanoconjugates, with a hydrodynamic size of around 50 nm, are stable and internalize target cells with a biological impact. Although the chemical conjugation minimizes the cytotoxic activity of the protein partner in the complexes, the concept of drug combination proposed here is fully feasible and highly promising when considering multiple drug treatments aimed to higher effectiveness or when facing the therapy of cancers with acquired resistance to classical drugs.

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.

Correlation between CXCR4, CXCR5 and CCR7 expression and survival outcomes in patients with clinical T1N0M0 non-small cell lung cancer

BACKGROUND

Lung cancer is the leading cause of cancer-related death. Even if early detection and treatment have proven to be effective, the survival outcomes are still poor.

METHODS

Tissue samples and clinicopathological data of 244 patients with clinical T1N0M0 NSCLC were collected. We investigated CXCR4, CXCR5 and CCR7 expression levels using the immunohistochemical method and analyzed their correlations with clinicopathological characteristics and survival outcomes.

RESULTS

Elevated expression levels of CXCR4, CXCR5 and CCR7 were found in tumor tissues (P < 0.001). The expression levels were remarkably different in histological type (CXCR4, P = 0.032; CXCR5, P < 0.001; CCR7, P < 0.001) and LVI (CXCR4, P = 0.017; CXCR5, P = 0.030; CCR7, P < 0.001). In addition, CXCR4 and CXCR5 expression were significantly different in tumor differentiation (CXCR4, P < 0.001; CXCR5, P < 0.001). Survival analysis showed that patients with positive CXCR4 expression had a significantly lower five-year DFS (P = 0.007) and a lower five-year OS (P = 0.010). Patients in the CXCR5 positive group had a significantly lower five-year DFS (P = 0.038) and a lower five-year OS (P = 0.220), which were statistically insignificant. However, five-year DFS and five-year OS of patients with positive CCR7 expression were significantly higher (DFS: P < 0.001; OS: P < 0.001). CXCR5 and CCR7 expression were found to be independent prognostic factors through multivariate analysis.

CONCLUSIONS

Expression levels of CXCR4, CXCR5 and CCR7 were significantly higher in tumor tissues, and expression of CXCR5 and CCR7 were independent prognostic factors for survival. Moreover, all three chemokines were correlated to the survival outcomes of patients with clinical T1N0M0 NSCLC, providing potential prognosticators and therapy targets for lung cancer treatment.

Leptin promotes bone metastasis of breast cancer by activating the SDF-1/CXCR4 axis

Obesity is associated with an increased risk of tumorigenesis, and increased leptin levels can promote tumor metastasis. However, the effects of leptin on bone metastasis in breast cancer are not fully understood. Here, we examined leptin receptor expression and bone metastasis in tissue samples from 96 breast cancer patients. In addition, we investigated the effects of leptin on the metastatic capacity of breast cancer cells in vitro using a transwell assays. The results indicated that higher leptin receptor levels in breast cancer cells are associated with increased incidence of bone metastasis in breast cancer patients. Additionally, leptin promoted migration and invasion of breast cancer cells. The SDF-1/CXCR4 axis activated by leptin also promoted bone metastasis of breast cancer. Finally, increased CXCR4 expression was accompanied by high leptin receptor expression in bone metastatic tissues from breast cancer patients. These results indicate that leptin induces bone metastasis of breast cancer by activating the SDF-1/CXCR4 axis.

Comprehensive analysis of the prognostic value and immune function of chemokine-CXC receptor family members in breast cancer

Recently, immune checkpoint inhibitors (ICIs) have been successfully used for treating melanoma. Unfortunately, many breast cancer (BC) patients show low response to ICIs due to the lack of infiltrating immune cells. Previous studies revealed that chemokine-CXC receptors (CXCRs) play a crucial role in leukocyte infiltration and promote cancer cell proliferation, migration, metastasis, and angiogenesis. However, the underlying functions of CXCRs in cancer-immunity cycle remain unclear. In this study, we firstly found that in comparison to normal tissues, BC tissues, especially basal-like BC, showed increased mRNA levels of CXCR3/4/5/6/8, but decreased CXCR1/2/7 expression using UALCAN and TIMER database. Interestingly, it's was found that the mRNA levels of CXCR3/4/5/6 were decreased in lymphocyte depleted of the BC immune subtype. Subsequently, functional enrichment analysis of distinct CXCRs indicated that CXCR3/4/5/6 were strongly associated to immune-related biological functions. Therefore, further analysis using TIMER and TISIDB database suggested that CXCR3/4/5/6 expression were strongly correlated with tumor-infiltrating lymphocytes (TILs) and immune checkpoints in BC. Finally, Kaplan-Meier Plotter analysis indicated that high mRNA expression of CXCR4 predicted worse relapse-free survival (RFS), whereas CXCR3/5/6 indicated better RFS in BC patients. These findings suggest a therapeutic value for CXCR3/4/5/6 in combination with ICIs for the treatment of BC.

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.

Cytotoxic drugs in combination with the CXCR4 antagonist AMD3100 as a potential treatment option for pediatric rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common type of pediatric soft tissue sarcoma. The prognosis of advanced stage RMS remains poor, and metastatic invasion is a major cause of treatment failure. Therefore, there is an urgent need for treatment alternatives focusing on metastatic invasion and drug resistance. The stromal cell‑derived factor‑1 (SDF‑1)/chemokine receptor 4 (CXCR4) axis is a crucial factor for metastatic invasion in RMS. Clinical data has revealed that high CXCR4 expression is associated with a poor outcome and a high metastatic rate in several malignancies, including RMS. Thus, targeting CXCR4 in addition to classical chemotherapy may improve the effectiveness of RMS treatment. In the present study, flow cytometry and reverse transcription‑quantitative PCR were used to assess the effects of the combined treatment with a CXCR4 antagonist and chemotherapy on CXCR4 expression in the embryonal RMS (RME) cell line RD and in the alveolar RMS (RMA) cell line RH30. The functional effect of CXCR4 expression on the migratory behavior of RMS cells was analyzed using Transwell assays. Treatment with cytotoxic agents modulated CXCR4 expression in RMS cells in a dose‑, drug‑ and cell line dependent manner; however, this was not observed in RD cells with vincristine. The expression levels of CXCR4 significantly increased the migratory behavior of RMA and did not affect RME cell migration towards stromal cell‑derived factor‑1α (SDF‑1α). AMD3100 markedly reduced the migration of RH30 cells in the Transwell assays compared with SDF‑1α alone, and the cytotoxic agents doxorubicin and vincristine increased this effect. The results of the combined treatment in RMS cells using the CXCR4 antagonist AMD3100 together with cytotoxic drugs demonstrated that this approach may be a promising alternative for the treatment of advanced stage pediatric RMS. The observed effects of circumventing metastatic invasion and drug resistance should be further investigated in vivo.

CXCR4 and JUNB double-positive disseminated tumor cells are detected frequently in breast cancer patients at primary diagnosis

Background:

The chemokine receptor CXCR4 and the transcription factor JUNB, expressed on a variety of tumor cells, seem to play an important role in the metastatic process. Since disseminated tumor cells (DTCs) in the bone marrow (BM) have been associated with worse outcomes, we evaluated the expression of CXCR4 and JUNB in DTCs of primary, nonmetastatic breast cancer (BC) patients before the onset of any systemic treatment.

Methods:

Bilateral BM (10 ml) aspirations of 39 hormone receptor (HR)-positive, HER2-negative BC patients were assessed for the presence of DTCs using the following combination of antibodies: pan-cytokeratin (A45-B/B3)/CXCR4/JUNB. An expression pattern of the examined proteins was created using confocal laser scanning microscopy, Image J software and BC cell lines.

Results:

CXCR4 was overexpressed in cancer cells and DTCs, with the following hierarchy of expression: SKBR3 > MCF7 > DTCs > MDA-MB231. Accordingly, the expression pattern of JUNB was: DTCs > MDA-MB231 > SKBR3 > MCF7. The mean intensity of CXCR4 (6411 ± 334) and JUNB (27725.64 ± 470) in DTCs was statistically higher compared with BM hematopoietic cells (2009 ± 456, p = 0.001; and 11112.89 ± 545, p = 0.001, respectively). The (CXCR4+JUNB+CK+) phenotype was the most frequently detected [90% (35/39)], followed by the (CXCR4–JUNB+CK+) phenotype [36% (14/39)]. However, (CXCR4+JUNB–CK+) tumor cells were found in only 5% (3/39) of patients. Those patients harboring DTCs with the (CXCR4+JUNB+CK+) phenotype revealed lower overall survival (Cox regression: p = 0.023).

Conclusions:

(CXCR4+JUNB+CK+)-expressing DTCs, detected frequently in the BM of BC patients, seem to identify a subgroup of patients at higher risk for relapse that may be considered for close follow up.

Quantitative Proteomics and Metabolomics Reveal Biomarkers of Disease as Potential Immunotherapy Targets and Indicators of Therapeutic Efficacy

Quantitative mass spectrometry (MS) continues to deepen our understanding of the immune system, quickly becoming the gold standard for obtaining high-throughput, quantitative data on biomolecules. The development of targeted and multiplexed assays for biomarker quantification makes MS an attractive tool both for diagnosing diseases and for quantifying the effects of immunotherapeutics. Because of its accuracy, the use of MS for identifying biomarkers of disease reduces the potential for misdiagnosis and overtreatment. Advances in workflows for sample processing have drastically reduced processing time and complexities due to sample preparation, making MS a more accessible technology. In this review, we present how recent developments in proteomics and metabolomics make MS an essential component of enhancing and monitoring the efficacy of immunotherapeutic treatments.

Role of Hedgehog Signaling in Breast Cancer: Pathogenesis and Therapeutics

Breast cancer (BC) is the leading cause of cancer-related mortality in women, only followed by lung cancer. Given the importance of BC in public health, it is essential to identify biomarkers to predict prognosis, predetermine drug resistance and provide treatment guidelines that include personalized targeted therapies. The Hedgehog (Hh) signaling pathway plays an essential role in embryonic development, tissue regeneration, and stem cell renewal. Several lines of evidence endorse the important role of canonical and non-canonical Hh signaling in BC. In this comprehensive review we discuss the role of Hh signaling in breast development and homeostasis and its contribution to tumorigenesis and progression of different subtypes of BC. We also examine the efficacy of agents targeting different components of the Hh pathway both in preclinical models and in clinical trials. The contribution of the Hh pathway in BC tumorigenesis and progression, its prognostic role, and its value as a therapeutic target vary according to the molecular, clinical, and histopathological characteristics of the BC patients. The evidence presented here highlights the relevance of the Hh signaling in BC, and suggest that this pathway is key for BC progression and metastasis.

GPCR Modulation in Breast Cancer

Breast cancer is the most prevalent cancer found in women living in developed countries. Endocrine therapy is the mainstay of treatment for hormone-responsive breast tumors (about 70% of all breast cancers) and implies the use of selective estrogen receptor modulators and aromatase inhibitors. In contrast, triple-negative breast cancer (TNBC), a highly heterogeneous disease that may account for up to 24% of all newly diagnosed cases, is hormone-independent and characterized by a poor prognosis. As drug resistance is common in all breast cancer subtypes despite the different treatment modalities, novel therapies targeting signaling transduction pathways involved in the processes of breast carcinogenesis, tumor promotion and metastasis have been subject to accurate consideration. G protein-coupled receptors (GPCRs) are the largest family of cell-surface receptors involved in the development and progression of many tumors including breast cancer. Here we discuss data regarding GPCR-mediated signaling, pharmacological properties and biological outputs toward breast cancer tumorigenesis and metastasis. Furthermore, we address several drugs that have shown an unexpected opportunity to interfere with GPCR-based breast tumorigenic signals.

High Cytoplasmic CXCR4 Expression Predicts Prolonged Survival in Triple-Negative Breast Cancer Patients Treated with Adjuvant Chemotherapy

BACKGROUND

Chemokine receptor CXC chemokine receptor type 4 (CXCR4) and its ligand CXC motif chemokine 12 (CXCL12; stromal cell-derived factor-1) are implicated in tumor growth, metastasis, and tumor cell-microenvironment interaction. A number of studies have reported that increased CXCR4 expression is associated with worse prognosis in triple-negative breast cancer (TNBC), but its prognostic significance has not been studied in TNBC patients treated with adjuvant chemotherapy.

METHODS

Two hundred eighty-three TNBC patients who received adjuvant chemotherapy were retrospectively analyzed. Tissue microarray was constructed from formalinfixed, paraffin-embedded tumor tissue and immunohistochemistry for CXCR4 and CXCL12 was performed. Expression of each marker was compared with clinicopathologic characteristics and outcome.

RESULTS

High cytoplasmic CXCR4 expression was associated with younger age (p = .008), higher histologic grade (p = .007) and lower pathologic stage (p = .045), while high CXCL12 expression was related to larger tumor size (p = .045), positive lymph node metastasis (p = .005), and higher pathologic stage (p = .017). The patients with high cytoplasmic CXCR4 experienced lower distant recurrence (p = .006) and better recurrence-free survival (RFS) (log-rank p = .020) after adjuvant chemotherapy. Cytoplasmic CXCR4 expression remained an independent factor of distant recurrence (p = .019) and RFS (p = .038) after multivariate analysis.

CONCLUSIONS

High cytoplasmic CXCR4 expression was associated with lower distant recurrence and better RFS in TNBC patients treated with adjuvant chemotherapy. This is the first study to correlate high CXCR4 expression to better TNBC prognosis, and the underlying mechanism needs to be elucidated in further studies.

The Role of CXC Chemokine Receptors 1-4 on Immune Cells in the Tumor Microenvironment

Chemokines govern leukocyte migration by attracting cells that express their cognate ligands. Many cancer types show altered chemokine secretion profiles, favoring the recruitment of pro-tumorigenic immune cells and preventing the accumulation of anti-tumorigenic effector cells. This can ultimately result in cancer immune evasion. The manipulation of chemokine and chemokine-receptor signaling can reshape the immunological phenotypes within the tumor microenvironment in order to increase the therapeutic efficacy of cancer immunotherapy. Here we discuss the three chemokine-chemokine receptor axes, CXCR1/2–CXCL1-3/5-8, CXCR3–CXCL9/10/11, and CXCR4-CXCL12 and their role on pro-tumorigenic immune cells and anti-tumorigenic effector cells in solid tumors. In particular, we summarize current strategies to target these axes and discuss their potential use in treatment approaches.

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.

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.

Role of chemokines in metastatic niche: new insights along with a diagnostic and prognostic approach

Chemokines are cytokines that are involved in the movement of leukocytes and the occurrence of immune responses. It has recently been noted that these cytokines play a role in the movement of cancer cells to different parts of the body and create a suitable environment [i.e. (pre) metastatic niche] for their growth and proliferation. We studied the role of chemokines in the metastasis of cancer cells, as well as their involvement in the proliferation and growth of these cells. Relevant literature was identified by a PubMed search (2005-2017) of English language papers using the terms 'chemokine,' 'metastasis niche,' and 'organotropism.' Based on the nature of cancer cells, the expression of chemokine receptors on these cells leads to metastasis to various organs, which ultimately causes changes in different signaling pathways. Finally, the targeting of chemokines on cancer cells could prevent the metastasis of cancer cells toward different organs.

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.

Bone Metastasis in Advanced Breast Cancer: Analysis of Gene Expression Microarray

BACKGROUND

Approximately 30% to 40% of breast cancer recurrences involve bone metastasis (BM). Certain genes have been linked to BM; however, none have been able to predict bone involvement. In this study, we analyzed gene expression profiles in advanced breast cancer patients to elucidate genes that can be used to predict BM.

PATIENTS AND METHODS

A total of 92 advanced breast cancer patients, including 46 patients with BM and 46 patients without BM, were identified for this study. Immunohistochemistry and gene expression analysis was performed on 81 formalin-fixed paraffin-embedded samples. Data were collected through medical records, and gene expression of 200 selected genes compiled from 6 previous studies was performed using NanoString nCounter.

RESULTS

Genetic expression profiles showed that 22 genes were significantly differentially expressed between breast cancer patients with metastasis in bone and other organs (BM+) and non-BM, whereas subjects with only BM showed 17 significantly differentially expressed genes. The following genes were associated with an increasing incidence of BM in the BM+ group: estrogen receptor 1 (ESR1), GATA binding protein 3 (GATA3), and melanophilin with an area under the curve (AUC) of 0.804. In the BM group, the following genes were associated with an increasing incidence of BM: ESR1, progesterone receptor, B-cell lymphoma 2, Rab escort protein, N-acetyltransferase 1, GATA3, annexin A9, and chromosome 9 open reading frame 116. ESR1 and GATA3 showed an increased strength of association with an AUC of 0.928.

CONCLUSION

A combination of the identified 3 genes in BM+ and 8 genes in BM showed better prediction than did each individual gene, and this combination can be used as a training set.

Krüppel-like factor 8 activates the transcription of C-X-C cytokine receptor type 4 to promote breast cancer cell invasion, transendothelial migration and metastasis

Krüppel-like factor 8 (KLF8) has been strongly implicated in breast cancer metastasis. However, the underlying mechanisms remain largely unknown. Here we report a novel signaling from KLF8 to C-X-C cytokine receptor type 4 (CXCR4) in breast cancer. Overexpression of KLF8 in MCF-10A cells induced CXCR4 expression at both mRNA and protein levels, as determined by quantitative real-time PCR and immunoblotting. This induction was well correlated with increased Boyden chamber migration, matrigel invasion and transendothelial migration (TEM) of the cells towards the ligand CXCL12. On the other hand, knockdown of KLF8 in MDA-MB-231 cells reduced CXCR4 expression associated with decreased cell migration, invasion and TEM towards CXCL12. Histological and database mining analyses of independent cohorts of patient tissue microarrays revealed a correlation of aberrant co-elevation of KLF8 and CXCR4 with metastatic potential. Promoter analysis indicated that KLF8 directly binds and activates the human CXCR4 gene promoter. Interestingly, a CXCR4-dependent activation of focal adhesion kinase (FAK), a known upregulator of KLF8, was highly induced by CXCL12 treatment in KLF8-overexpressing, but not KLF8 deficient cells. This activation of FAK in turn induced a further increase in KLF8 expression. Xenograft studies showed that overexpression of CXCR4, but not a dominant-negative mutant of it, in the MDA-MB-231 cells prevented the invasive growth of primary tumor and lung metastasis from inhibition by knockdown of KLF8. These results collectively suggest a critical role for a previously unidentified feed-forward signaling wheel made of KLF8, CXCR4 and FAK in promoting breast cancer metastasis and shed new light on potentially more effective anti-cancer strategies.

MicroRNA-126 inhibits colon cancer cell proliferation and invasion by targeting the chemokine (C-X-C motif) receptor 4 and Ras homolog gene family, member A, signaling pathway

MicroRNA-126 (miR-126) suppresses the migration, proliferation and invasion of colon cancer cells. However, the underlying mechanisms of miR-126 in colon cancer have not been fully elucidated. In this study, in vivo experiments revealed that miR-126 inhibits colon cancer growth and metastasis. Furthermore, miR-126 was down-regulated in human colon cancer tissue, and its expression was inversely correlated with TNM stage and metastasis of patients. Low level of miR-126 identified patients with poor prognosis. And we found that miR-126 expression was negatively correlated with the expression levels of chemokine (C-X-C motif) receptor 4 (CXCR4) and components of signaling pathway of Ras homolog gene family, member A (RhoA) in vitro and in vivo. Moreover, we verified that miR-126 negatively regulated CXCR4 and RhoA signaling in vitro. In addition, either in miR-126-overexpressing or in miR- 126-silenced colon cancer cells, the restoration of CXCR4 could significantly reverse the proliferation and invasion, as well as abolish the effects of miR-126 on RhoA signaling pathway. Collectively, these results demonstrated that miR-126 acts as a tumor suppressor by inactivating RhoA signaling via CXCR4 in colon cancer. And miR-126 may serve as a prognostic marker for monitoring and treating colon cancer.

The good and bad faces of the CXCR4 chemokine receptor

Chemokines are chemotactic cytokines that promote cell migration and activation under homeostatic and inflammatory conditions. Chemokines bind to seven transmembrane-spanning receptors that are coupled to heterotrimeric guanine nucleotide-binding (G) proteins, which are the responsible for intracellularly transmitting the activating signals for cell migration. Hematopoiesis, vascular development, lymphoid organ morphogenesis, cardiogenesis and neural differentiation are amongst the processes involving chemokine function. In addition, immune cell trafficking from bone marrow to blood circulation, and from blood and lymph to lymphoid and inflamed tissues, is tightly regulated by chemokines both under physiological conditions and also in autoimmune diseases. Furthermore, chemokine binding to their receptors stimulate trafficking to and positioning of cancer cells into target tissues and organs during tumour dissemination. The CXCL12 chemokine (also known as stromal-cell derived factor-1α, SDF-1α) plays key roles in hematopoiesis and lymphoid tissue architecture, in cardiogenesis, vascular formation and neurogenesis, as well as in the trafficking of solid and hematological cancer cell types. CXCL12 binds to the CXCR4 receptor, a multi-facetted molecule which tightly mirrors CXCL12 functions in homeostasis and disease. This review addresses the important roles of the CXCR4-CXCL12 axis in homeostasis, specially focusing in hematopoiesis, as well as it provides a picture of CXCR4 as mediator of cancer cell spreading, and a view of the available CXCR4 antagonists in different cancer types.

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.

Serum SDF-1 levels are a reliable diagnostic marker of feline mammary carcinoma, discriminating HER2-overexpressing tumors from other subtypes

The feline mammary carcinoma (FMC) is the third most common tumor in cat, sharing many clinicopathological features with human breast cancer and thus, considered a suitable model for comparative oncology. Due to its poor prognosis, further studies are required to improve the diagnostic accuracy and treatment of cats with spontaneous mammary carcinoma. Recently, it was reported that the overexpression of stromal cell-derived factor-1 (SDF-1) has great value in human breast cancer diagnosis, suggesting that diagnostic tools and therapies targeting the SDF-1 ligand can improve the clinical outcome. In this study, we aimed to evaluate if serum SDF-1 levels can also be used as a biomarker of mammary carcinoma in cats and to analyze if serum SDF-1 levels are associated with clinicopathological features, linked to a specific FMC subtype or correlated with the tumor expression of SDF-1 receptor, the chemokine C-X-C motif receptor 4 (CXCR4). Results showed that cats with mammary carcinoma had significantly higher serum SDF-1 levels than healthy controls (p=0.035) and ROC analysis revealed that the best cut-off value to differentiate sick from healthy animals was 2 ng/ml (specificity: 80%; sensitivity: 57%; AUC=0.715). Significant associations were also found between cats with elevated serum SDF-1 concentrations (≥ 2 ng/ml) and HER2-overexpressing mammary carcinomas (Luminal B-like and HER2-positive subtypes, p<0.0001), CXCR4-negative mammary carcinomas (p=0.027), mammary carcinomas with small size (<3 cm, p=0.027) and tumors with low Ki-67 expression (p=0.012). No statistical associations were found between serum SDF-1 levels and overall or disease-free survival. In summary, our results show that serum SDF-1 levels can be used as a biomarker of feline mammary carcinoma, especially in cats with HER2-overexpressing mammary tumors. Data suggest that targeted therapies against the SDF-1 ligand and/or its CXC4 receptor may be effective for the treatment of FMC, as described for human breast cancer, strengthening the concept that spontaneous feline mammary carcinoma is a suitable model for comparative oncology.

Prognostic genes of breast cancer revealed by gene co-expression network analysis

The aim of the present study was to identify genes that may serve as markers for breast cancer prognosis by constructing a gene co-expression network and mining modules associated with survival. Two gene expression datasets of breast cancer were downloaded from ArrayExpress and genes from these datasets with a coefficient of variation >0.5 were selected and underwent functional enrichment analysis with the Database for Annotation, Visualization and Integration Discovery. Gene co-expression networks were constructed with the WGCNA package in R. Modules were identified from the network via cluster analysis. Cox regression was conducted to analyze survival rates. A total of 2,669 genes were selected, and functional enrichment analysis of them revealed that they were mainly associated with the immune response, cell proliferation, cell differentiation and cell adhesion. Seven modules were identified from the gene co-expression network, one of which was found to be significantly associated with patient survival time. Expression status of 144 genes from this module was used to cluster patient samples into two groups, with a significant difference in survival time revealed between these groups. These genes were involved in the cell cycle and tumor protein p53 signaling pathway. The top 10 hub genes were identified in the module. The findings of the present study could advance the understanding of the molecular pathogenesis of breast cancer.