The paradoxical functions of EGFR during breast cancer progression

Screening of phytochemicals from Clerodendrum inerme (L.) Gaertn as potential anti-breast cancer compounds targeting EGFR: an in-silico approach

Breast cancer (BC) is the most prevalent malignancy among women around the world. The epidermal growth factor receptor (EGFR) is a tyrosine kinase receptor (RTK) of the ErbB/HER family. It is essential for triggering the cellular signaling cascades that control cell growth and survival. However, perturbations in EGFR signaling lead to cancer development and progression. Hence, EGFR is regarded as a prominent therapeutic target for breast cancer. Therefore, in the current investigation, EGFR was targeted with phytochemicals from Clerodendrum inerme (L.) Gaertn (C. inerme). A total of 121 phytochemicals identified by gas chromatography-mass spectrometry (GC-MS) analysis were screened against EGFR through molecular docking, ADMET analyses (Absorption, Distribution, Metabolism, Excretion, and Toxicity), PASS predictions, and molecular dynamics simulation, which revealed three potential hit compounds with CIDs 10586 [i.e. alpha-bisabolol (-6.4 kcal/mol)], 550281 [i.e. 2,(4,4-Trimethyl-3-hydroxymethyl-5a-(3-methyl-but-2-enyl)-cyclohexene) (-6.5 kcal/mol)], and 161271 [i.e. salvigenin (-7.4 kcal/mol)]. The FDA-approved drug gefitinib was used to compare the inhibitory effects of the phytochemicals. The top selected compounds exhibited good ADMET properties and obeyed Lipinski's rule of five (ROF). The molecular docking analysis showed that salvigenin was the best among the three compounds and formed bonds with the key residue Met 793. Furthermore, the molecular mechanics generalized born surface area (MMGBSA) calculations, molecular dynamics simulation, and normal mode analysis validated the binding affinity of the compounds and also revealed the strong stability and compactness of phytochemicals at the docked site. Additionally, DFT and DOS analyses were done to study the reactivity of the compounds and to further validate the selected phytochemicals. These results suggest that the identified phytochemicals possess high inhibitory potential against the target EGFR and can treat breast cancer. However, further in vitro and in vivo investigations are warranted towards the development of these constituents into novel anti-cancer drugs.

L858R/L718Q and L858R/L792H Mutations of EGFR Inducing Resistance Against Osimertinib by Forming Additional Hydrogen Bonds

Acquired resistance to first-line treatments in various cancers both promotes cancer recurrence as well as limits effective treatment. This is true for epidermal growth factor receptor (EGFR) mutations, for which secondary EGFR mutations are one of the principal mechanisms conferring resistance to the covalent inhibitor osimertinib. Thus, it is very important to develop a deeper understanding of the secondary mutational resistance mechanisms associated with EGFR mutations arising in tumors treated with osimertinib to expedite the development of innovative therapeutic drugs to overcome acquired resistance. This work uses all-atom molecular dynamics (MD) simulations to investigate the conformational variation of two reported EGFR mutants (L858R/L718Q and L858R/L792H) that resist osimertinib. The wild-type EGFR kinase domain and the L858R mutant are used as the reference. Our MD simulation results revealed that both the L718Q and L792H secondary mutations induce additional hydrogen bonds between the residues in the active pocket and the residues with the water molecules. These additional hydrogen bonds reduce the exposure area of C797, the covalent binding target of osimertinib. The additional hydrogen bonds also influence the binding affinity of the EGFR kinase domain by altering the secondary structure and flexibility of the amino acid residues in the domain. Our work highlights how the two reported mutations may alter both residue-residue and residue-solvent hydrogen bonds, affecting protein binding properties, which could be helpful for future drug discovery.

Surface Functionalization of Nanocarriers with Anti-EGFR Ligands for Cancer Active Targeting

Active cancer targeting consists of the selective recognition of overexpressed biomarkers on cancer cell surfaces or within the tumor microenvironment, enabled by ligands conjugated to drug carriers. Nanoparticle (NP)-based systems are highly relevant for such an approach due to their large surface area which is amenable to a variety of chemical modifications. Over the past decades, several studies have debated the efficiency of passive targeting, highlighting active targeting as a more specific and selective approach. The choice of conjugation chemistry for attaching ligands to nanocarriers is critical to ensure a stable and robust system. Among the panel of cancer biomarkers, the epidermal growth factor receptor (EGFR) stands as one of the most frequently overexpressed receptors in different cancer types. The design and development of nanocarriers with surface-bound anti-EGFR ligands are vital for targeted therapy, relying on their facilitated capture by EGFR-overexpressing tumor cells and enabling receptor-mediated endocytosis to improve drug accumulation within the tumor microenvironment. In this review, we examine several examples of the most recent and significant anti-EGFR nanocarriers and explore the various conjugation strategies for NP functionalization with anti-EGFR biomolecules and small molecular ligands. In addition, we also describe some of the most common characterization techniques to confirm and analyze the conjugation patterns.

Integrated Network Pharmacology, Machine Learning and Experimental Validation to Identify the Key Targets and Compounds of TiaoShenGongJian for the Treatment of Breast Cancer

Background

TiaoShenGongJian (TSGJ) decoction, a traditional Chinese medicine for breast cancer, has unknown active compounds, targets, and mechanisms. This study identifies TSGJ's key targets and compounds for breast cancer treatment through network pharmacology, machine learning, and experimental validation.

Methods

Bioactive components and targets of TSGJ were identified from the TCMSP database, and breast cancer-related targets from GeneCards, PharmGkb, and RNA-seq datasets. Intersection of these targets revealed therapeutic targets of TSGJ. PPI analysis was performed via STRING, and machine learning methods (SVM, RF, GLM, XGBoost) identified key targets, validated by GSE70905, GSE70947, GSE22820, and TCGA-BRCA datasets. Pathway analyses and molecular docking were performed. TSGJ and core compounds' effectiveness was confirmed by MTT and RT-qPCR assays.

Results

160 common targets of TSGJ were identified, with 30 hub targets from PPI analysis. Five predictive targets (HIF1A, CASP8, FOS, EGFR, PPARG) were screened via SVM. Their diagnostic, biomarker, immune, and clinical values were validated. Quercetin, luteolin, and baicalein were identified as core components. Molecular docking confirmed their strong affinities with predicted targets. These compounds modulated key targets and induced cytotoxicity in breast cancer cell lines in a similar way as TSGJ.

Conclusion

This study reveals the main active components and targets of TSGJ against breast cancer, supporting its potential for breast cancer prevention and treatment.

Advancements in Global Phosphoproteomics Profiling: Overcoming Challenges in Sensitivity and Quantification

Protein phosphorylation introduces post-genomic diversity to proteins, which plays a crucial role in various cellular activities. Elucidation of system-wide signaling cascades requires high-performance tools for precise identification and quantification of dynamics of site-specific phosphorylation events. Recent advances in phosphoproteomic technologies have enabled the comprehensive mapping of the dynamic phosphoproteomic landscape, which has opened new avenues for exploring cell type-specific functional networks underlying cellular functions and clinical phenotypes. Here, we provide an overview of the basics and challenges of phosphoproteomics, as well as the technological evolution and current state-of-the-art global and quantitative phosphoproteomics methodologies. With a specific focus on highly sensitive platforms, we summarize recent trends and innovations in miniaturized sample preparation strategies for micro-to-nanoscale and single-cell profiling, data-independent acquisition mass spectrometry (DIA-MS) for enhanced coverage, and quantitative phosphoproteomic pipelines for deep mapping of cell and disease biology. Each aspect of phosphoproteomic analysis presents unique challenges and opportunities for improvement and innovation. We specifically highlight evolving phosphoproteomic technologies that enable deep profiling from low-input samples. Finally, we discuss the persistent challenges in phosphoproteomic technologies, including the feasibility of nanoscale and single-cell phosphoproteomics, as well as future outlooks for biomedical applications.

Combining Water-Soluble Porphyrin and Phthalocyanine Photosensitizers With Doxorubicin Improves the Efficacy of Chemo-Photodynamic Therapy Against DMBA-Induced Breast Carcinoma

Breast cancer ranks as the second most widespread form of cancer globally. Currently, combination therapy is being actively employed in clinical practice to augment the efficiency of anticancer treatment. Hence, the objective of this study was to assess the therapeutic efficacy of a combination of femtosecond laser-based photodynamic therapy (PDT) utilizing two distinct photosensitizers (PSs), zinc phthalocyanine tetrasulfonate (ZnPcS4) and α,β,χ,δ porphyrin-Tetrakis (1-methylpyridinium-4-yl) p-Toluenesulfonate porphyrin (TMPyP) in conjunction with doxorubicin chemotherapeutic agent, on mammary carcinomas experimentally induced in female mice using 7,12-dimethylbenz[a] anthracene (DMBA). Our results showed the efficiency of the combined therapy for promoting tissue apoptosis and necrosis as evidenced by histopathological observations and the noticeable reduction of Bcl-2 and Ki-67 expression. Moreover, there was a reduction in serum levels of the carcinoma antigen CA15-3 and transforming growth factor beta (TGF-β). Co-treatment of doxorubicin with ZnPcS4-PDT or TMPyP-PDT or a combination of both resulted in a decrease in the expression of epidermal growth factor receptor (EGFR) and its downstream oncogenes NRAS, NF-κB, mTERT, and c-Myc, and an increase in the expression of the caspase-3 apoptotic gene. These results validate the therapeutic potential of combining doxorubicin with PDT, highlighting the potential of this co-treatment strategy as a promising alternative for enhancing existing anticancer approaches.

Targeting RTKs/nRTKs as promising therapeutic strategies for the treatment of triple-negative breast cancer: evidence from clinical trials

The extensive heterogeneity and the limited availability of effective targeted therapies contribute to the challenging prognosis and restricted survival observed in triple-negative breast cancer (TNBC). Recent research indicates the aberrant expression of diverse tyrosine kinases (TKs) within this cancer, contributing significantly to tumor cell proliferation, survival, invasion, and migration. The contemporary paradigm shift towards precision medicine has highlighted TKs and their receptors as promising targets for pharmacotherapy against a range of malignancies, given their pivotal roles in tumor initiation, progression, and advancement. Intensive investigations have focused on various monoclonal antibodies (mAbs) and small molecule inhibitors that specifically target proteins such as epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor (VEGFR), cellular mesenchymal-epithelial transition factor (c-MET), human epidermal growth factor receptor 2 (HER2), among others, for combating TNBC. These agents have been studied both in monotherapy and in combination with other chemotherapeutic agents. Despite these advances, a substantial terrain of unexplored potential lies within the realm of TK targeted therapeutics, which hold promise in reshaping the therapeutic landscape. This review summarizes the various TK targeted therapeutics that have undergone scrutiny as potential therapeutic interventions for TNBC, dissecting the outcomes and revelations stemming from diverse clinical investigations. A key conclusion from the umbrella clinical trials evidences the necessity for in-depth molecular characterization of TNBCs for the maximum efficiency of TK targeted therapeutics, either as standalone treatments or a combination. Moreover, our observation highlights that the outcomes of TK targeted therapeutics in TNBC are substantially influenced by the diversity of the patient cohort, emphasizing the prioritization of individual patient genetic/molecular profiles for precise TNBC patient stratification for clinical studies.

NoxO1 regulates EGFR signaling by its interaction with Erbin

NADPH oxidase organizer 1 (NoxO1) is a scaffold cytoplasmic subunit of the reactive oxygen species (ROS) forming Nox1 complex and involved in angiogenesis, differentiation, and atherosclerosis. We found that overexpression of NoxO1 without simultaneous overexpression of any other component of the active Nox1 complex inhibited EGF-induced wound closure and signaling, while NoxO1 KO yielded the opposite effect. Accordingly, we hypothesize NoxO1 to exert Nox1 independent functions. Using the BioID technique, we identified ErbB2 interacting protein (Erbin) as novel interaction partner of NoxO1. Colocalization of NoxO1 with EGFR, as well as with Erbin validated this finding. EGF treatment interrupted colocalization of NoxO1 and EGFR. EGF mediated kinase activation was delayed in NoxO1 overexpressing cells, while knockout of NoxO1 had the opposite effect. In conclusion, Erbin was identified as a novel NoxO1 interacting protein. Through the subsequent interaction of NoxO1 and EGFR, NoxO1 interferes with EGF signaling. The results of this study suggest a potential role of NoxO1 as an adaptor protein with functions beyond the well-established enabling of Nox1 mediated ROS formation.

Immunohistochemical Expression of Caspase1 and Epidermal Growth Factor Receptor in Invasive Breast Carcinoma and Their Biological and Prognostic Associations

BACKGROUND

Despite advances in breast carcinoma therapies, drug resistance mechanisms as anti-apoptosis and anti-pyroptosis limit the application of these therapies. This work assesses the immunohistochemical (IHC) expression of Caspase1 and EGFR in breast carcinoma and analyzes their clinicopathological associations as prognostic markers and potential therapeutic targets. Caspase1/EGFR expression patterns are utilized to specify breast carcinoma patients who may benefit from these therapies.

METHODS

After reviewing the hematoxylin and eosin-stained slides and the routine breast carcinoma IHC stains (estrogen receptors, progesterone receptors, HER2/NEU, Ki-67) by two pathologists and preparation of tissue microarray blocks, anti-Caspase-1 and EGFR IHC staining was performed using Horseradish Peroxidase (HRP) technique. Intensity and percentage-based scoring was applied dividing the 153 included breast carcinomas into Caspase1-negative and positive expression groups; and EGFR low and overexpression groups. Groups were statistically analyzed in relation to age, tumor size, histological and molecular subtype, grade, nodal status, metastasis/recurrence, TNM stage and Ki-67 proliferation index. Kaplan-Meier's analysis was used to compare disease-free survival (DFS) and overall survival (OS). Combined patterns based on Caspase1 and EGFR expression status were created to stratify patients into prognostic groups.

RESULTS

Caspase1 was positive in 54.2% of breast carcinomas and its positivity was significantly associated with smaller tumor size, absence of metastasis/recurrence, luminal A and B molecular subtypes and longer OS (p<0.05). EGFR overexpression was detected in 32.7% of carcinomas and was significantly associated with larger tumor size, TNBLBC and a shorter OS (p<0.05). Caspase1-negative/EGFR-overexpression pattern comprised 14.4% of carcinomas and had the worst prognostic associations including larger tumor size, metastasis/recurrence, TNBLBC subtype and shortest OS (p=0.002, 0.002, 0.004 and ≤0.001 respectively).  Conclusions: Combined Caspase1/EGFR IHC expression may provide a tool for selection of patients who benefit from combined EGFR-inhibitors with miR-155-5p down-regulators or photodynamic therapy via induction of apoptosis/pyroptosis in EGFR-overexpression carcinomas through enhanced Caspase1 signaling.

Oxygen tension-dependent variability in the cancer cell kinome impacts signaling pathways and response to targeted therapies

Most cells in solid tumors are exposed to oxygen levels between 0.5% and 5%. We developed an approach that allows collection, processing, and evaluation of cancer and non-cancer cells under physioxia, while preventing exposure to ambient air. This aided comparison of baseline and drug-induced changes in signaling pathways under physioxia and ambient oxygen. Using tumor cells from transgenic models of breast cancer and cells from breast tissues of clinically breast cancer-free women, we demonstrate oxygen-dependent differences in cell preference for epidermal growth factor receptor (EGFR) or platelet-derived growth factor receptor beta (PDGFRβ) signaling. Physioxia caused PDGFRβ-mediated activation of AKT and extracellular regulated kinase (ERK) that reduced sensitivity to EGFR and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) inhibition and maintained PDGFRβ+ epithelial-mesenchymal hybrid cells with potential cancer stem cell (CSC) properties. Cells in ambient air displayed differential EGFR activation and were more sensitive to targeted therapies. Our data emphasize the importance of oxygen considerations in preclinical cancer research to identify effective drug targets and develop combination therapy regimens.

Tuning Peptide-Based Nanofibers for Achieving Selective Doxorubicin Delivery in Triple-Negative Breast Cancer

Introduction

The design of delivery tools that efficiently transport drugs into cells remains a major challenge in drug development for most pathological conditions. Triple-negative breast cancer (TNBC) is a very aggressive subtype of breast cancer with poor prognosis and limited effective therapeutic options.

Purpose

In TNBC treatment, chemotherapy remains the milestone, and doxorubicin (Dox) represents the first-line systemic treatment; however, its non-selective distribution causes a cascade of side effects. To address these problems, we developed a delivery platform based on the self-assembly of amphiphilic peptides carrying several moieties on their surfaces, aimed at targeting, enhancing penetration, and therapy.

Methods

Through a single-step self-assembly process, we used amphiphilic peptides to obtain nanofibers decorated on their surfaces with the selected moieties. The surface of the nanofiber was decorated with a cell-penetrating peptide (gH625), an EGFR-targeting peptide (P22), and Dox bound to the cleavage sequence selectively recognized and cleaved by MMP-9 to obtain on-demand drug release. Detailed physicochemical and cellular analyses were performed.

Results

The obtained nanofiber (NF-Dox) had a length of 250 nm and a diameter of 10 nm, and it was stable under dilution, ionic strength, and different pH environments. The biological results showed that the presence of gH625 favored the complete internalization of NF-Dox after 1h in MDA-MB 231 cells, mainly through a translocation mechanism. Interestingly, we observed the absence of toxicity of the carrier (NF) on both healthy cells such as HaCaT and TNBC cancer lines, while a similar antiproliferative effect was observed on TNBC cells after the treatment with the free-Dox at 50 µM and NF-Dox carrying 7.5 µM of Dox.

Discussion

We envision that this platform is extremely versatile and can be used to efficiently carry and deliver diverse moieties. The knowledge acquired from this study will provide important guidelines for applications in basic research and biomedicine.

MerTK Drives Proliferation and Metastatic Potential in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is characterized by the absence of the estrogen receptor, progesterone receptor, and receptor tyrosine kinase HER2 expression. Due to the limited number of FDA-approved targeted therapies for TNBC, there is an ongoing need to understand the molecular underpinnings of TNBC for the development of novel combinatorial treatment strategies. This study evaluated the role of the MerTK receptor tyrosine kinase on proliferation and invasion/metastatic potential in TNBC. Immunohistochemical analysis demonstrated MerTK expression in 58% of patient-derived TNBC xenografts. The stable overexpression of MerTK in human TNBC cell lines induced an increase in proliferation rates, robust in vivo tumor growth, heightened migration/invasion potential, and enhanced lung metastases. NanoString nCounter analysis of MerTK-overexpressing SUM102 cells (SUM102-MerTK) revealed upregulation of several signaling pathways, which ultimately drive cell cycle progression, reduce apoptosis, and enhance cell survival. Proteomic profiling indicated increased endoglin (ENG) production in SUM102-MerTK clones, suggesting that MerTK creates a conducive environment for increased proliferative and metastatic activity via elevated ENG expression. To determine ENG's role in increasing proliferation and/or metastatic potential, we knocked out ENG in a SUM102-MerTK clone with CRISPR technology. Although this ENG knockout clone exhibited similar in vivo growth to the parental SUM102-MerTK clone, lung metastasis numbers were significantly decreased ~4-fold, indicating that MerTK enhances invasion and metastasis through ENG. Our data suggest that MerTK regulates a unique proliferative signature in TNBC, promoting robust tumor growth and increased metastatic potential through ENG upregulation. Targeting MerTK and ENG simultaneously may provide a novel therapeutic approach for TNBC patients.

An Innovative Mitochondrial-targeted Gene Therapy for Cancer Treatment

Targeting cancer cell mitochondria holds great therapeutic promise, yet current strategies to specifically and effectively destroy cancer mitochondria in vivo are limited. Here, we introduce mLumiOpto, an innovative mitochondrial-targeted luminoptogenetics gene therapy designed to directly disrupt the inner mitochondrial membrane (IMM) potential and induce cancer cell death. We synthesize a blue light-gated channelrhodopsin (CoChR) in the IMM and co-express a blue bioluminescence-emitting Nanoluciferase (NLuc) in the cytosol of the same cells. The mLumiOpto genes are selectively delivered to cancer cells in vivo by using adeno-associated virus (AAV) carrying a cancer-specific promoter or cancer-targeted monoclonal antibody-tagged exosome-associated AAV. Induction with NLuc luciferin elicits robust endogenous bioluminescence, which activates mitochondrial CoChR, triggering cancer cell IMM permeability disruption, mitochondrial damage, and subsequent cell death. Importantly, mLumiOpto demonstrates remarkable efficacy in reducing tumor burden and killing tumor cells in glioblastoma or triple-negative breast cancer xenografted mouse models. These findings establish mLumiOpto as a novel and promising therapeutic strategy by targeting cancer cell mitochondria in vivo.

Dysregulated Gab1 signalling in triple negative breast cancer

BACKGROUND

Breast cancer is the most common cancer in women worldwide. Triple-negative breast cancer (TNBC) is especially aggressive and associated with high metastasis. The aetiology of TNBC is heterogeneous and characterised by multiple different mutations that amongst others cause constitutive and dysregulated MAPK and PI3K signalling. Additionally, in more than 50% of TNBC patients, the epidermal growth factor receptor (EGFR) is overexpressed and constitutively active. The multi-site docking protein Grb2-associated binder 1 (Gab1) is a central signalling hub that connects MAPK and PI3K signalling.

METHODS

Expression and activation of members of the Gab1/PI3K/MAPK signalling network were assessed in cells from different breast cancer subtypes. Influence of short- and long-term inhibition of EGFR, MAPK and PI3K on the activation of the Gab1/PI3K/MAPK signalling network as well as on cell viability, proliferation and migration was determined. Additionally, cellular localisation of Gab1 and Gab1 variants in naive cells and cells treated with the above-mentioned inhibitors was investigated.

RESULTS

We show that, activation of the Gab1/PI3K/MAPK signalling network is heterogeneous between different breast cancer subtypes. Gab1 phosphorylation and plasma membrane recruitment of Gab1 are dysregulated in the EGFRhigh TNBC cell line MDA-MB-468. While the Gab1/MAPK/PI3K signalling network follows canonical Gab1 signalling in naive MDA-MB-468 cells, Gab1 signalling is changed in cells that acquired resistance towards MAPK and PI3K inhibition. In resistant cells, Gab1 is not located at the plasma membrane despite strong activation of PI3K and MAPK. Furthermore, Gab1 tyrosine phosphorylation is uncoupled from plasma membrane recruitment.

CONCLUSION

Our study indicates that Gab1 signalling changes fundamentally during the acquisition of resistance to pharmacological inhibitors. Given the molecular heterogeneity between breast cancer subtypes, the detailed understanding of dysregulated and aberrant signalling is an absolute necessity in order to develop personalised therapies for patients with TNBC.

Receptor mediated targeting of EGF-conjugated alginate-PAMAM nanoparticles to lung adenocarcinoma: 2D/3D in vitro and in vivo evaluation

Carboplatin (cis-diamine (1,1-cyclobutandicarboxylaso)‑platinum (II)) is a second-generation antineoplastic drug, which is widely used for chemotherapy of lung, colon, breast, cervix, testicular and digestive system cancers. Although preferred over cisplatin due to the lower incidence of nephrotoxicity and ototoxicity, efficient carboplatin delivery remains as a major challenge. In this study, carboplatin loaded alginate- poly(amidoamine) (PAMAM) hybrid nanoparticles (CAPs) with mean sizes of 192.13 ± 4.15 nm were synthesized using a microfluidic platform, then EGF was conjugated to the surface of CAPs (EGF-CAPs) for the receptor-targeted delivery. Hence, increased FITC+ cell counts were observed in A549 spheroids after EGF-CAP treatment compared to CAP in the 3D cellular uptake study. As such, the cytotoxicity of EGF-CAP was approximately 2-fold higher with an IC50 value of 35.89 ± 10.37 μg/mL compared to the CAPs in A549 spheroids. Based on in vivo experimental animal model, anti-tumor activities of the group treated with CAP decreased by 61 %, whereas the group treated with EGF-CAP completely recovered. Additionally, EGF-CAP application was shown to induce apoptotic cell death. Our study provided a new strategy for designing a hybrid nanoparticle for EGFR targeted carboplatin delivery with improved efficacy both in vitro and in vivo applications.

Isolation, Cytotoxicity, and In-silico Screening of Coumarins from Psoralea corylifolia Linn

Psoralea corylifolia (syn. Cullen corylifolium), commonly called bawachi, is a medicinal plant extensively used for skin conditions like leukoderma, vitiligo, and psoriasis. It is notably rich in valuable bioactive compounds, particularly coumarins and furanocoumarins. This study isolated fourteen coumarins from P. corylifolia which were tested for cytotoxicity using the MTT assay, with compound 10 showing good cytotoxicity against A549 cells (IC50 0.9 μM), while compound 1, compound 2, and compound 3 displaying potential cytotoxicity against MDA-MB-231 cells (IC50 0.49 μM, 0.56 μM, and 0.84 μM respectively). Additionally, the compounds' interaction with Epidermal Growth Factor Receptor (EGFR) protein, highly expressed in both cell lines, was investigated through molecular modeling studies, that aligned well with cytotoxicity results. The findings revealed the remarkable cytotoxic potential of four coumarins 1, 2, 3, and 10 against A549 and MDA-MB-231 cell lines.

Platelet membrane-based biochemotactic-targeting nanoplatform combining PDT with EGFR inhibition therapy for the treatment of breast cancer

Presently, the commonly used anti-tumor drugs lack targeting ability, resulting in a limited therapeutic efficacy and significant side effects. In this view, platelet membranes (PMs) not only exhibit specific binding of its P-selectin protein with CD44, which is highly expressed on breast cancer cells, to promote tumor-active targeting by PM biomimetic nanoplatforms, but also respond to vascular damage, thus inducing biochemotactic targeting to further facilitate the aggregation of these nanoplatforms. Therefore, in this study, a PM was applied to construct a biochemotactic-targeting nanotherapeutic platform based on dendritic large pore mesoporous silica nanoparticles (DLMSNs) co-loaded with chlorin e6 (Ce6) and lapatinib (LAP) to achieve the combination of photodynamic therapy (PDT) and EGFR inhibition therapy for breast cancer. Under laser irradiation, PM@DLMSN/Ce6/Lap could not only effectively kill breast tumor cells by the PDT, but also damage blood vessels. By combining the EGFR inhibition of LAP, PM@DLMSN/Ce6/Lap could better inhibit the migration and movement of tumor cells. In vitro and in vivo results showed that PM@DLMSN/Ce6/Lap could achieve active-targeting drug delivery to breast tumors and further recruit more nanoparticles to accumulate at tumor sites after the PDT-induced damage of blood vessels through biochemotactic targeting, achieving continuous EGFR inhibition to prevent tumor proliferation and metastasis. In conclusion, this study not only provides a new strategy for the clinical treatment of breast cancer, but also provides a design idea for improving the targeted delivery of anti-tumor drugs.

Prognostic Markers in Tyrosine Kinases Specific to Basal-like 2 Subtype of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC), a heterogeneous and therapeutically challenging subtype, comprises over 50% of patients categorized into basal-like 1 (BL1) and basal-like 2 (BL2) intrinsic molecular subtypes. Despite their shared basal-like classification, BL2 is associated with a poor response to neoadjuvant chemotherapy and reduced relapse-free survival compared to BL1. Here, the study focused on identifying subtype-specific markers for BL2 through transcriptomic analysis of TNBC patients using RNA-seq and clinical integration. Six receptor tyrosine kinase (TK) genes, including EGFR, EPHA4, EPHB2, PDGFRA, PDGFRB, and ROR1, were identified as potential differentiators for BL2. Correlations between TK mRNA expression and TNBC prognosis, particularly EGFR, PDGFRA, and PDGFRB, revealed potential synergistic interactions in pathways related to cell survival and proliferation. Our findings also suggest promising dual markers for predicting disease prognosis. Furthermore, RT-qPCR validation demonstrated that identified BL2-specific TKs were expressed at a higher level in BL2 than in BL1 cell lines, providing insights into unique characteristics. This study advances the understanding of TNBC heterogeneity within the basal-like subtypes, which could lead to novel clinical treatment approaches and the development of targeted therapies.

Thinking (Metastasis) outside the (Primary Tumor) Box

The metastasis of tumor cells into vital organs is a major cause of death from diverse types of malignancies [...].

Discovering the anti-cancer phytochemical rutin against breast cancer through the methodical platform based on traditional medicinal knowledge

A number of therapeutic drugs have been developed from functional chemicals found in plants. Knowledge of plants used for medicinal purposes has historically been transmitted by word of mouth or through literature. The aim of the present study is to provide a systemic platform for the development of lead compounds against breast cancer based on a traditional medical text. To verify our systematic approach, integrating processes consisted of text mining of traditional medical texts, 3-D virtual docking screening, and in vitro and in vivo experimental validations were demonstrated. Our text analysis system identified rutin as a specific phytochemical traditionally used for cancer treatment. 3-D virtual screening predicted that rutin could block EGFR signaling. Thus, we validated significant anticancer effects of rutin against breast cancer cells through blockade of EGFR signaling pathway in vitro. We also demonstrated in vivo anti-cancer effects of rutin using the breast cancer recurrence in vivo models. In summary, our innovative approach might be proper for discovering new phytochemical lead compounds designing for blockade of malignant neoplasm including breast cancer. [BMB Reports 2023; 56(11): 594-599].

Cooperative regulation of coupled oncoprotein synthesis and stability in triple-negative breast cancer by EGFR and CDK12/13

Evidence has long suggested that epidermal growth factor receptor (EGFR) may play a prominent role in triple-negative breast cancer (TNBC) pathogenesis, but clinical trials of EGFR inhibitors have yielded disappointing results. Using a candidate drug screen, we identified that inhibition of cyclin-dependent kinases 12 and 13 (CDK12/13) dramatically sensitizes diverse models of TNBC to EGFR blockade. This combination therapy drives cell death through the 4E-BP1-dependent suppression of the translation and translation-linked turnover of driver oncoproteins, including MYC. A genome-wide CRISPR/Cas9 screen identified the CCR4-NOT complex as a major determinant of sensitivity to the combination therapy whose loss renders 4E-BP1 unresponsive to drug-induced dephosphorylation, thereby rescuing MYC translational suppression and promoting MYC stability. The central roles of CCR4-NOT and 4E-BP1 in response to the combination therapy were further underscored by the observation of CNOT1 loss and rescue of 4E-BP1 phosphorylation in TNBC cells that naturally evolved therapy resistance. Thus, pharmacological inhibition of CDK12/13 reveals a long-proposed EGFR dependence in TNBC that functions through the cooperative regulation of translation-coupled oncoprotein stability.

Abrogating Metastatic Properties of Triple-Negative Breast Cancer Cells by EGFR and PI3K Dual Inhibitors

Triple-negative breast cancer (TNBC) is a devastating BC subtype. Its aggressiveness, allied to the lack of well-defined molecular targets, usually culminates in the appearance of metastases that account for poor prognosis, particularly when they develop in the brain. Nevertheless, TNBC has been associated with epidermal growth factor receptor (EGFR) overexpression, leading to downstream phosphoinositide 3-kinase (PI3K) signaling activation. We aimed to unravel novel drug candidates for TNBC treatment based on EGFR and/or PI3K inhibition. Using a highly metastatic TNBC cell line with brain tropism (MDA-MB-231 Br4) and a library of 27 drug candidates in silico predicted to inhibit EGFR, PI3K, or EGFR plus PI3K, and to cross the blood-brain barrier, we evaluated the effects on cell viability. The half maximal inhibitory concentration (IC50) of the most cytotoxic ones was established, and cell cycle and death, as well as migration and EGFR pathway intervenient, were further evaluated. Two dual inhibitors emerged as the most promising drugs, with the ability to modulate cell cycle, death, migration and proliferation, morphology, and PI3K/AKT cascade players such as myocyte enhancer factor 2C (MEF2C) and forkhead box P1 (FOXP1). This work revealed EGFR/PI3K dual inhibitors as strong candidates to tackle brain metastatic TNBC cells.

Distinct shared and compartment-enriched oncogenic networks drive primary versus metastatic breast cancer

Metastatic breast-cancer is a major cause of death in women worldwide, yet the relationship between oncogenic drivers that promote metastatic versus primary cancer is still contentious. To elucidate this relationship in treatment-naive animals, we hereby describe mammary-specific transposon-mutagenesis screens in female mice together with loss-of-function Rb, which is frequently inactivated in breast-cancer. We report gene-centric common insertion-sites (gCIS) that are enriched in primary-tumors, in metastases or shared by both compartments. Shared-gCIS comprise a major MET-RAS network, whereas metastasis-gCIS form three additional hubs: Rho-signaling, Ubiquitination and RNA-processing. Pathway analysis of four clinical cohorts with paired primary-tumors and metastases reveals similar organization in human breast-cancer with subtype-specific shared-drivers (e.g. RB1-loss, TP53-loss, high MET, RAS, ER), primary-enriched (EGFR, TGFβ and STAT3) and metastasis-enriched (RHO, PI3K) oncogenic signaling. Inhibitors of RB1-deficiency or MET plus RHO-signaling cooperate to block cell migration and drive tumor cell-death. Thus, targeting shared- and metastasis- but not primary-enriched derivers offers a rational avenue to prevent metastatic breast-cancer.

Dual kinase inhibitor for EGFR mutants and ErbB2 limit breast cancer

Mutations in the epidermal growth factor receptor (EGFR) have been found in more than 10% of non-small cell lung cancer (NSCLC) patients in North America. The vast majority of these differences are L858R point mutations in Exon 21. Currently, monoclonal antibodies directed against the extracellular domain of EGFR or small molecule/tyrosine kinase inhibitors (TKI) are the stalwarts of NSCLC therapy. Resistance, however, gradually develops because of the T790 mutation towards first and second generation TKIs. The third generation TKI AZD9291 (Osimertinib) has a high affinity for both activating and the acquired resistant mutation (T790 M) in EGFR, with a low affinity towards wild-type EGFR. Recent research, however, suggests that the EGFR (C797S) mutation in the tyrosine kinase domain is a likely cause of resistance to AZD9291. Another significant transformation mechanism associated with this resistance is erbB2 amplification. Our laboratory has developed a small kinase inhibitor, ER121 (MW: ∼500), that inhibits the erbB2/HER2 tyrosine kinases in addition to the EGFR C797S mutations. We have identified a TKI, ER121 targeting the mutant EGFR(T790 M). Using in vitro and in vivo models, examined the efficacy of ER121 on mutant EGFR cell lines. This has enabled us to establish that ER121 is well tolerated when administered orally and produces significant inhibitory activity against human cancers generated by mutant EGFR and amplified ErbB2.

Targeted Therapy and Mechanisms of Drug Resistance in Breast Cancer

Breast cancer is the most common cause of cancer-related death in women worldwide. Multidrug resistance (MDR) has been a large hurdle in reducing BC death rates. The drug resistance mechanisms include increased drug efflux, enhanced DNA repair, senescence escape, epigenetic alterations, tumor heterogeneity, tumor microenvironment (TME), and the epithelial-to-mesenchymal transition (EMT), which make it challenging to overcome. This review aims to explain the mechanisms of resistance in BC further, identify viable drug targets, and elucidate how those targets relate to the progression of BC and drug resistance.

The anticancer and EGFR-TK/CDK-9 dual inhibitory potentials of new synthetic pyranopyrazole and pyrazolone derivatives: X-ray crystallography, in vitro, and in silico mechanistic investigations

Treatment options for the management of breast cancer are still inadequate. This inadequacy is attributed to the lack of effective targeted medications, often resulting in the recurrence of metastatic disorders. Cumulative evidence suggests that epidermal growth factor receptor (EGFR-TK) and cyclin-dependent kinases-9 (CDK-9) overexpression correlates with worse overall survival in breast cancer patients. Pyranopyrazole and pyrazolone are privileged options for the development of anticancer agents. Inspired by this proven scientific fact, we report here the synthesis of two new series of suggested anticancer molecules incorporating both heterocycles together with their characterization by IR, 1H NMR, 13C NMR, 13C NMR-DEPT, and X-ray diffraction methods. An attempt to get the pyranopyrazole-gold complexes was conducted but unexpectedly yielded benzylidene-2,4-dihydro-3H-pyrazol-3-one instead. This unexpected result was confirmed by X-ray crystallographic analysis. All newly synthesized compounds were assessed for their anti-proliferative activity against two different human breast cancer cells, and the obtained results were compared with the reference drug Staurosporine. The target compounds revealed variable cytotoxicity with IC50 at a low micromolar range with superior selectivity indices. Target enzyme EGFR-TK and CDK-9 assays showed that compounds 22 and 23 effectively inhibited both biological targets with IC50 values of 0.143 and 0.121 µM, respectively. Molecular docking experiments and molecular dynamics simulation were also conducted to further rationalize the in vitro obtained results.Communicated by Ramaswamy H. Sarma.

Proteomic quantification of receptor tyrosine kinases involved in the development and progression of colorectal cancer liver metastasis

Introduction

Alterations in expression and activity of human receptor tyrosine kinases (RTKs) are associated with cancer progression and in response to therapeutic intervention.

Methods

Thus, protein abundance of 21 RTKs was assessed in 15 healthy and 18 cancerous liver samples [2 primary and 16 colorectal cancer liver metastasis (CRLM)] matched with non-tumorous (histologically normal) tissue, by a validated QconCAT-based targeted proteomic approach.

Results

It was demonstrated, for the first time, that the abundance of EGFR, INSR, VGFR3 and AXL, is lower in tumours relative to livers from healthy individuals whilst the opposite is true for IGF1R. EPHA2 was upregulated in tumour compared with histologically normal tissue surrounding it. PGFRB levels were higher in tumours relative to both histologically normal tissue surrounding tumour and tissues taken from healthy individuals. The abundances of VGFR1/2, PGFRA, KIT, CSF1R, FLT3, FGFR1/3, ERBB2, NTRK2, TIE2, RET, and MET were, however, comparable in all samples. Statistically significant, but moderate correlations were observed (Rs > 0.50, p < 0.05) for EGFR with INSR and KIT. FGFR2 correlated with PGFRA and VGFR1 with NTRK2 in healthy livers. In non-tumorous (histologically normal) tissues from cancer patients, there were correlations between TIE2 and FGFR1, EPHA2 and VGFR3, FGFR3 and PGFRA (p < 0.05). EGFR correlated with INSR, ERBB2, KIT and EGFR, and KIT with AXL and FGFR2. In tumours, CSF1R correlated with AXL, EPHA2 with PGFRA, and NTRK2 with PGFRB and AXL. Sex, liver lobe and body mass index of donors had no impact on the abundance of RTKs, although donor age showed some correlations. RET was the most abundant of these kinases in non-tumorous tissues (~35%), while PGFRB was the most abundant RTK in tumours (~47%). Several correlations were also observed between the abundance of RTKs and proteins relevant to drug pharmacokinetics (enzymes and transporters).

Discussion

DiscussionThis study quantified perturbation to the abundance of several RTKs in cancer and the value generated in this study can be used as input to systems biology models defining liver cancer metastases and biomarkers of its progression.

Tumor-associated macrophages respond to chemotherapy by detrimental transcriptional reprogramming and suppressing stabilin-1 mediated clearance of EGF

Introduction

Tumor resistance to chemotherapy and metastatic relapse account for more than 90% of cancer specific mortality. Tumor-associated macrophages (TAMs) can process chemotherapeutic agents and impair their action. Little is known about the direct effects of chemotherapy on TAMs.

Methods

The effect of chemotherapeutic platinum agent cisplatin was assessed in the model system of human ex vivo TAMs. Whole-transcriptome sequencing for paired TAMs stimulated and not stimulated by cisplatin was analysed by NGS. Endocytic uptake of EGF was quantified by flow cytometry. Confocal microscopy was used to visualize stabilin-1-mediated internalization and endocytic trafficking of EGF in CHO cells expressing ectopically recombinant stabilin-1 and in stabilin-1+ TAMs. In cohort of patients with breast cancer, the effect of platinum therapy on the transcriptome of TAMs was validated, and differential expression of regulators of endocytosis was identified.

Results

Here we show that chemotherapeutic agent cisplatin can initiate detrimental transcriptional and functional programs in TAMs, without significant impairment of their viability. We focused on the clearance function of TAMs that controls composition of tumor microenvironment. For the first time we demonstrated that TAMs' scavenger receptor stabilin-1 is responsible for the clearance of epidermal growth factor (EGF), a potent stimulator of tumor growth. Cisplatin suppressed both overall and EGF-specific endocytosis in TAMs by bidirectional mode: suppression of positive regulators and stimulation of negative regulators of endocytosis, with strongest effect on synaptotagmin-11 (SYT11), confirmed in patients with breast cancer.

Conclusion

Our data demonstrate that synergistic action of cytostatic agents and innovative immunomodulators is required to overcome cancer therapy resistance.

Breast tumor IGF1R regulates cell adhesion and metastasis: alignment of mouse single cell and human breast cancer transcriptomics

Introduction

The acquisition of a metastatic phenotype is the critical event that determines patient survival from breast cancer. Several receptor tyrosine kinases have functions both in promoting and inhibiting metastasis in breast tumors. Although the insulin-like growth factor 1 receptor (IGF1R) has been considered a target for inhibition in breast cancer, low levels of IGF1R expression are associated with worse overall patient survival.

Methods

To determine how reduced IGF1R impacts tumor phenotype in human breast cancers, we used weighted gene co-expression network analysis (WGCNA) of Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) patient data to identify gene modules associated with low IGF1R expression. We then compared these modules to single cell gene expression analyses and phenotypes of mouse mammary tumors with reduced IGF1R signaling or expression in a tumor model of triple negative breast cancer.

Results

WGCNA from METABRIC data revealed gene modules specific to cell cycle, adhesion, and immune cell signaling that were inversely correlated with IGF1R expression in human breast cancers. Integration of human patient data with single cell sequencing data from mouse tumors revealed similar pathways necessary for promoting metastasis in basal-like mammary tumors with reduced signaling or expression of IGF1R. Functional analyses revealed the basis for the enhanced metastatic phenotype including alterations in E- and P-cadherins.

Discussion

Human breast and mouse mammary tumors with reduced IGF1R are associated with upregulation of several pathways necessary for promoting metastasis supporting the conclusion that IGF1R normally helps maintain a metastasis suppressive tumor microenvironment. We further found that reduced IGF1R signaling in tumor epithelial cells dysregulates cadherin expression resulting in reduced cell adhesion.

'Why is survival with triple negative breast cancer so low? insights and talking points from preclinical and clinical research'

INTRODUCTION

Triple negative breast cancer is typically related to poor prognosis, early metastasis, and high recurrence rate. Intrinsic and extrinsic biological features of TNBC and resistance mechanisms to conventional therapies can support its aggressive behavior, characterizing TNBC how extremely heterogeneous. Novel combination strategies are under investigation, including immunotherapeutic agents, anti-drug conjugates, PARP inhibitors, and various targeting agents, exploring, in the meanwhile, possible predictive biomarkers to correctly select patients for the optimal treatment for their specific subtype.

AREAS COVERED

This article examines the main malignity characteristics across different subtype, both histological and molecular, and the resistance mechanisms, both primary and acquired, to different drugs explored in the landscape of TNBC treatment, that lead TNBC to still has high mortality rate.

EXPERT OPINION

The complexity of TNBC is not only the main reason of its aggressivity, but its heterogeneity should be exploited in terms of therapeutics opportunities, combining agents with different mechanism of action, after a correct selection by biologic or molecular biomarkers. The main goal is to understand what TNBC really is and to act selectively on its characteristics, with a personalized anticancer treatment.

PEGylated Strontium Sulfite Nanoparticles with Spontaneously Formed Surface-Embedded Protein Corona Restrict Off-Target Distribution and Accelerate Breast Tumour-Selective Delivery of siRNA

As transporters of RNAi therapeutics in preclinical and clinical studies, the application of nanoparticles is often hindered by their susceptibility to opsonin-mediated clearance, poor biological stability, ineffectual targeting, and undesirable effects on healthy cells. Prolonging the blood circulation time while minimizing the off-target distribution and associated toxicity is indispensable for the establishment of a clinically viable delivery system for therapeutic small interfering RNAs (siRNAs). Herein, we report a scalable and straightforward approach to fabricate non-toxic and biodegradable pH-responsive strontium sulfite nanoparticles (SSNs) wrapped with a hydrophilic coating material, biotinylated PEG to lessen unforeseen biological interactions. Surface functionalization of SSNs with PEG led to the generation of small and uniformly distributed particles with a significant affinity towards siRNAs and augmented internalization into breast cancer cells. A triple quadrupole liquid chromatography-mass spectrometry (LC-MS) was deployed to identify the proteins entrapped onto the SSNs, with the help of SwissProt.Mus_musculus database. The results demonstrated the reduction of opsonin proteins adsorption owing to the stealth effect of PEG. The distribution of PEGylated SSNs in mice after 4 h and 24 h of intravenous administration in breast tumour-bearing mice was found to be significantly less to the organs of the reticuloendothelial system (RES) and augmented accumulation in the tumour region. The anti-EGFR siRNA-loaded PEG-SSNs exerted a significant inhibitory effect on tumour development in the murine breast cancer model without any significant toxicity to healthy tissues. Therefore, PEGylated SSNs open up a new avenue for tumour-selective efficient delivery of siRNAs in managing breast cancer.

Low lamin A levels enhance confined cell migration and metastatic capacity in breast cancer

Aberrations in nuclear size and shape are commonly used to identify cancerous tissue. However, it remains unclear whether the disturbed nuclear structure directly contributes to the cancer pathology or is merely a consequence of other events occurring during tumorigenesis. Here, we show that highly invasive and proliferative breast cancer cells frequently exhibit Akt-driven lower expression of the nuclear envelope proteins lamin A/C, leading to increased nuclear deformability that permits enhanced cell migration through confined environments that mimic interstitial spaces encountered during metastasis. Importantly, increasing lamin A/C expression in highly invasive breast cancer cells reflected gene expression changes characteristic of human breast tumors with higher LMNA expression, and specifically affected pathways related to cell-ECM interactions, cell metabolism, and PI3K/Akt signaling. Further supporting an important role of lamins in breast cancer metastasis, analysis of lamin levels in human breast tumors revealed a significant association between lower lamin A levels, Akt signaling, and decreased disease-free survival. These findings suggest that downregulation of lamin A/C in breast cancer cells may influence both cellular physical properties and biochemical signaling to promote metastatic progression.

Review article epithelial to mesenchymal transition‑associated microRNAs in breast cancer

Despite major advances, breast cancer (BC) is the most commonly diagnosed carcinoma and remains a deadly disease among women worldwide. Many researchers point toward an important role of an epithelial to mesenchymal transition (EMT) in BC development and promoting metastasis. Here, will be discussed that how functional changes of transcription factors, signaling pathways, and microRNAs (miRNA) in BC promote EMT. A thorough understanding the EMT biology can be important to determine reversing the process and design treatment approaches. There are frequent debates as to whether EMT is really relevant to BC in vivo, in which due to the intrinsic heterogeneity and tumor microenvironment. Nevertheless, given the importance of EMT in cancer progression and metastasis, the implementation of therapies against cancer-associated EMT will continue to help us develop and test potential treatments.

Structure-based design and synthesis of a novel long-chain 4''-alkyl ether derivative of EGCG as potent EGFR inhibitor: in vitro and in silico studies

Herein, we report the discovery of a novel long-chain ether derivative of (-)-epigallocatechin-3-gallate (EGCG), a major green tea polyphenol as a potent EGFR inhibitor. A series of 4''-alkyl EGCG derivatives have been synthesized via regio-selectively alkylating the 4'' hydroxyl group in the D-ring of EGCG and tested for their antiproliferative activities against high (A431), moderate (HeLa), and low (MCF-7) EGFR-expressing cancer cell lines. The most potent compound, 4''-C14 EGCG showed the lowest IC50 values across all the tested cell lines. 4''-C14 EGCG was also found to be significantly more stable than EGCG under physiological conditions (PBS at pH 7.4). Further western blot analysis and imaging data revealed that 4''-C14 EGCG induced cell death in A431 cells with shrunken nuclei, nuclear fragmentation, membrane blebbing, and increased population of apoptotic cells where BAX upregulation and BCLXL downregulation were observed. In addition, autophosphorylation of EGFR and its downstream signalling proteins Akt and ERK were markedly inhibited by 4''-C14 EGCG. MD simulation and the MM/PBSA analysis disclosed the binding mode of 4''-C14 EGCG in the ATP-binding site of EGFR kinase domain. Taken together, our findings demonstrate that 4''-C14 EGCG can act as a promising potent EGFR inhibitor with enhanced stability.

Fucoxanthin Is a Potential Therapeutic Agent for the Treatment of Breast Cancer

Breast cancer (BC) is one of the most common cancers diagnosed and the leading cause of cancer-related death in women. Although there are first-line treatments for BC, drug resistances and adverse events have been reported. Given the incidence of BC keeps increasing, seeking novel therapeutics is urgently needed. Fucoxanthin (Fx) is a dietary carotenoid commonly found in seaweeds and diatoms. Both in vitro and in vivo studies show that Fx and its deacetylated metabolite fucoxanthinol (Fxol) inhibit and prevent BC growth. The NF-κB signaling pathway is considered the major pathway contributing to the anti-proliferation, anti-angiogenesis and pro-apoptotic effects of Fx and Fxol. Other signaling molecules such as MAPK, MMP2/9, CYP and ROS are also involved in the anti-cancer effects by regulating the tumor microenvironment, cancer metastasis, carcinogen metabolism and oxidation. Besides, Fx also possesses anti-obesity effects by regulating UCP1 levels and lipid metabolism, which may help to reduce BC risk. More importantly, mounting evidence demonstrates that Fx overcomes drug resistance. This review aims to give an updated summary of the anti-cancer effects of Fx and summarize the underlying mechanisms of action, which will provide novel strategies for the development of Fx as an anti-cancer therapeutic agent.

Emerging drug targets for triple-negative breast cancer: a guided tour of the preclinical landscape

INTRODUCTION

Triple-negative breast cancer (TNBC) is the most fatal molecular subtype of breast cancer because of its aggressiveness and resistance to chemotherapy. FDA-approved therapies for TNBC are limited to poly(ADP-ribose) polymerase inhibitors, immune checkpoint inhibitors, and trophoblast cell surface antigen 2-targeted antibody-drug conjugate. Therefore, developing a novel effective targeted therapy for TNBC is an urgent unmet need.

AREAS COVERED

In this narrative review, we discuss emerging targets for TNBC treatment discovered in early translational studies. We focus on cancer cell membrane molecules, hyperactive intracellular signaling pathways, and the tumor microenvironment (TME) based on their druggability, therapeutic potency, specificity to TNBC, and application in immunotherapy.

EXPERT OPINION

The significant challenges in the identification and validation of TNBC-associated targets are 1) application of appropriate genetic, molecular, and immunological approaches for modulating the target, 2) establishment of a proper mouse model that accurately represents the human immune TME, 3) TNBC molecular heterogeneity, and 4) failure translation of preclinical findings to clinical practice. To overcome those difficulties, future research needs to apply novel technology, such as single-cell RNA sequencing, thermostable group II intron reverse transcriptase sequencing, and humanized mouse models. Further, combination treatment targeting multiple pathways in both the TNBC tumor and its TME is essential for effective disease control.

DNA damage alters EGFR signaling and reprograms cellular response via Mre-11

To combat the various DNA lesions and their harmful effects, cells have evolved different strategies, collectively referred as DNA damage response (DDR). The DDR largely relies on intranuclear protein networks, which sense DNA lesions, recruit DNA repair enzymes, and coordinates several aspects of the cellular response, including a temporary cell cycle arrest. In addition, external cues mediated by the surface EGF receptor (EGFR) through downstream signaling pathways contribute to the cellular DNA repair capacity. However, cell cycle progression driven by EGFR activation should be reconciled with cell cycle arrest necessary for effective DNA repair. Here, we show that in damaged cells, the expression of Mig-6 (mitogen-inducible gene 6), a known regulator of EGFR signaling, is reduced resulting in heightened EGFR phosphorylation and downstream signaling. These changes in Mig-6 expression and EGFR signaling do not occur in cells deficient of Mre-11, a component of the MRN complex, playing a central role in double-strand break (DSB) repair or when cells are treated with the MRN inhibitor, mirin. RNAseq and functional analysis reveal that DNA damage induces a shift in cell response to EGFR triggering that potentiates DDR-induced p53 pathway and cell cycle arrest. These data demonstrate that the cellular response to EGFR triggering is skewed by components of the DDR, thus providing a plausible explanation for the paradox of the known role played by a growth factor such as EGFR in the DNA damage repair.

Therapeutic Targeting of Stromal-Tumor HGF-cMET Signaling in an Organotypic Triple Negative Breast Tumor Model

The tumor microenvironment (TME) promotes proliferation, drug resistance, and invasiveness of cancer cells. Therapeutic targeting of the TME is an attractive strategy to improve outcomes for patients, particularly in aggressive cancers such as triple negative breast cancer (TNBC) that have a rich stroma and limited targeted therapies. However, lack of preclinical human tumor models for mechanistic understanding of tumor-stromal interactions has been an impediment to identify effective treatments against the TME. To address this need, we developed a three-dimensional (3D) organotypic tumor model to study interactions of patient-derived cancer-associated fibroblasts (CAFs) with TNBC cells and explore potential therapy targets. We found that CAFs predominantly secreted hepatocyte growth factor (HGF) and activated MET receptor tyrosine kinase in TNBC cells. This tumor-stromal interaction promoted invasiveness, epithelial-to-mesenchymal transition, and activities of multiple oncogenic pathways in TNBC cells. Importantly, we established that TNBC cells become resistant to monotherapy and demonstrated a design-driven approach to select drug combinations that effectively inhibit pro-metastatic functions of TNBC cells. Our study also showed that HGF-MET from lung fibroblasts promotes colony formation by TNBC cells, suggesting that blocking HGF-MET signaling potentially could target both primary TNBC tumorigenesis and lung metastasis. Overall, we established the utility of our organotypic tumor model to identify and therapeutically target specific mechanisms of tumor-stromal interactions in TNBC toward the goal of developing targeted therapies against the TME. Implications: Leveraging a state-of-the-art organotypic tumor model, we demonstrated that CAFs-mediated HGF-MET signaling drive tumorigenic activities in TNBC and presents a therapeutic target.

Targeting Ribosome Biogenesis to Combat Tamoxifen Resistance in ER+ve Breast Cancer

Breast cancer is a heterogeneous disease. Around 70% of breast cancers are estrogen receptor-positive (ER+ve), with tamoxifen being most commonly used as an adjuvant treatment to prevent recurrence and metastasis. However, half of the patients will eventually develop tamoxifen resistance. The overexpression of c-MYC can drive the development of ER+ve breast cancer and confer tamoxifen resistance through multiple pathways. One key mechanism is to enhance ribosome biogenesis, synthesising mature ribosomes. The over-production of ribosomes sustains the demand for proteins necessary to maintain a high cell proliferation rate and combat apoptosis induced by therapeutic agents. c-MYC overexpression can induce the expression of eIF4E that favours the translation of structured mRNA to produce oncogenic factors that promote cell proliferation and confer tamoxifen resistance. Either non-phosphorylated or phosphorylated eIF4E can mediate such an effect. Since ribosomes play an essential role in c-MYC-mediated cancer development, suppressing ribosome biogenesis may help reduce aggressiveness and reverse tamoxifen resistance in breast cancer. CX-5461, CX-3543 and haemanthamine have been shown to repress ribosome biogenesis. Using these chemicals might help reverse tamoxifen resistance in ER+ve breast cancer, provided that c-MYC-mediated ribosome biogenesis is the crucial factor for tamoxifen resistance. To employ these ribosome biogenesis inhibitors to combat tamoxifen resistance in the future, identification of predictive markers will be necessary.

Association of EGFR mutations in second primary lung cancer and HER2 expression in breast cancer survivors

Background

The incidence of second primary lung cancer (SPLC) is increasing with longer survival rates from breast cancer. Despite of studies to suggest the mutual exclusivity of epidermal growth factor receptor (EGFR) and human epidermal growth receptor 2 (HER2) in several cancers, the effect of HER2 expression in breast cancer on EGFR mutations in SPLC is unclear. Therefore, this study aimed to determine the association between HER2 expression and EGFR mutations.

Methods

We conducted a retrospective cohort study of breast cancer survivors diagnosed with SPLC after breast cancer treatment between 1997 and 2018. We investigated the association between HER2 expression in breast cancer and EGFR mutations in SPLC, specifically focusing on negative correlations by using logistic regression analysis.

Results

EGFR mutations in SPLC were detected in 19 of 38 patients. Analysis for HER2 revealed a statistically significant difference in the proportion of EGFR mutations between patients with SPLC and previous HER2 positive breast cancer (43.5%) and those with SPLC and previous HER2 negative breast cancer (90.0%; P=0.021). The ratio of EGFR mutations decreased with the degree of HER2 expression in patients with previous breast cancer (90.0%: for no HER2 expression, 62.5% for HER2 1+, 0.0% for HER2 2+, and 41.7% for HER2 3+; P=0.018). Multivariate logistic analyses revealed that EGFR mutations in SPLC were significantly associated with age [odds ratio (OR): 1.11, 95% confidence interval (CI): 1.01-0.23, P=0.039] and HER2 positive status (OR: 0.04, 95% CI: 0.01-0.56, P=0.017).

Conclusions

This study suggests that the frequency of EGFR mutations in SPLC may be associated with low HER2 expression in previous breast cancer.

Triple-Negative Breast Cancer: A Brief Review About Epidemiology, Risk Factors, Signaling Pathways, Treatment and Role of Artificial Intelligence

Triple-negative breast cancer (TNBC) is a kind of breast cancer that lacks estrogen, progesterone, and human epidermal growth factor receptor 2. This cancer is responsible for more than 15-20% of all breast cancers and is of particular research interest as it is therapeutically challenging mainly because of its low response to therapeutics and highly invasive nature. The non-availability of specific treatment options for TNBC is usually managed by conventional therapy, which often leads to relapse. The focus of this review is to provide up-to-date information related to TNBC epidemiology, risk factors, metastasis, different signaling pathways, and the pathways that can be blocked, immune suppressive cells of the TNBC microenvironment, current and investigation therapies, prognosis, and the role of artificial intelligence in TNBC diagnosis. The data presented in this paper may be helpful for researchers working in the field to obtain general and particular information to advance the understanding of TNBC and provide suitable disease management in the future.

Targeted EV to Deliver Chemotherapy to Treat Triple-Negative Breast Cancers

Triple-negative breast cancers (TNBCs) are heterogeneous and metastatic, and targeted therapy is highly needed for TNBC treatment. Recent studies showed that extracellular vesicles (EV) have great potential to deliver therapies to treat cancers. This study aimed to develop and evaluate a natural compound, verrucarin A (Ver-A), delivered by targeted EV, to treat TNBC. First, the surface expression of epidermal growth factor receptor (EGFR) and CD47 were confirmed with immunohistochemistry (IHC) staining of patient tissue microarray, flow cytometry and Western blotting. EVs were isolated from HEK 293F culture and surface tagged with anti-EGFR/CD47 mAbs to construct mAb-EV. The flow cytometry, confocal imaging and live-animal In Vivo Imaging System (IVIS) demonstrated that mAb-EV could effectively target TNBC and deliver the drug. The drug Ver-A, with dosage-dependent high cytotoxicity to TNBC cells, was packed in mAb-EV. The anti-TNBC efficacy study showed that Ver-A blocked tumor growth in both 4T1 xenografted immunocompetent mouse models and TNBC patient-derived xenograft models with minimal side effects. This study demonstrated that the targeted mAb-EV-Ver-A had great potential to treat TNBCs.

Genome-wide and transcriptome-wide association studies of mammographic density phenotypes reveal novel loci

BACKGROUND

Mammographic density (MD) phenotypes, including percent density (PMD), area of dense tissue (DA), and area of non-dense tissue (NDA), are associated with breast cancer risk. Twin studies suggest that MD phenotypes are highly heritable. However, only a small proportion of their variance is explained by identified genetic variants.

METHODS

We conducted a genome-wide association study, as well as a transcriptome-wide association study (TWAS), of age- and BMI-adjusted DA, NDA, and PMD in up to 27,900 European-ancestry women from the MODE/BCAC consortia.

RESULTS

We identified 28 genome-wide significant loci for MD phenotypes, including nine novel signals (5q11.2, 5q14.1, 5q31.1, 5q33.3, 5q35.1, 7p11.2, 8q24.13, 12p11.2, 16q12.2). Further, 45% of all known breast cancer SNPs were associated with at least one MD phenotype at p < 0.05. TWAS further identified two novel genes (SHOX2 and CRISPLD2) whose genetically predicted expression was significantly associated with MD phenotypes.

CONCLUSIONS

Our findings provided novel insight into the genetic background of MD phenotypes, and further demonstrated their shared genetic basis with breast cancer.

EGF-SNX3-EGFR axis drives tumor progression and metastasis in triple-negative breast cancers

Epidermal growth factor receptor (EGFR) has critical roles in epithelial cell physiology. Over-expression and over-activation of EGFR have been implicated in diverse cancers, including triple-negative breast cancers (TNBCs), prompting anti-EGFR therapies. Therefore, developing potent therapies and addressing the inevitable drug resistance mechanisms necessitates deciphering of EGFR related networks. Here, we describe Sorting Nexin 3 (SNX3), a member of the recycling retromer complex, as a critical player in the epidermal growth factor (EGF) stimulated EGFR network in TNBCs. We show that SNX3 is an immediate and sustained target of EGF stimulation initially at the protein level and later at the transcriptional level, causing increased SNX3 abundance. Using a proximity labeling approach, we observed increased interaction of SNX3 and EGFR upon EGF stimulation. We also detected colocalization of SNX3 with early endosomes and endocytosed EGF. Moreover, we show that EGFR protein levels are sensitive to SNX3 loss. Transient RNAi models of SNX3 downregulation have a temporary reduction in EGFR levels. In contrast, long-term silencing forces cells to recover and overexpress EGFR mRNA and protein, resulting in increased proliferation, colony formation, migration, invasion in TNBC cells, and increased tumor growth and metastasis in syngeneic models. Consistent with these results, low SNX3 and high EGFR mRNA levels correlate with poor relapse-free survival in breast cancer patients. Overall, our results suggest that SNX3 is a critical player in the EGFR network in TNBCs with implications for other cancers dependent on EGFR activity.

mRNA expression of specific HER ligands and their association with clinical outcome in patients with metastatic breast cancer treated with trastuzumab

Prognostic and predictive biomarkers are being studied for the diagnosis and treatment of breast cancer. The present study retrospectively assessed the mRNA expression of HER family receptor ligands and of other potential prognostic biomarkers and their association with time to progression (TTP), survival and clinicopathological characteristics in patients with metastatic breast cancer (MBC) treated with trastuzumab. A total of 145 tumour tissue samples were analysed. mRNA expression analysis of the transcripts of interest was performed and the association of these markers with selected clinicopathological parameters was examined. HER2 status was centrally re-evaluated. Only 67.6% of patients were truly HER2-positive according to the central HER2 re-evaluation. Heparin binding epidermal growth factor (EGF)-like growth factor, transforming growth factor β1 (TGFB1) and thyroid hormone receptor α (THRA) mRNA expression was higher in HER2-positive patients (P=0.026, P<0.001 and P<0.001). Insulin-like growth factor binding protein 4 was correlated with retinoic acid receptor α, TGFB1 and THRA (rho=0.45, rho=0.60 and rho=0.45). In HER2-positive patients, high neuregulin 1 and high betacellulin were unfavourable factors for TTP [hazard ratio (HR) = 1.78, P=0.040 and HR=2.00, P=0.043, respectively]. In patients with de novo MBC, high EGF expression was associated with a non-significant prolongation of TTP (HR=0.52, P=0.080) and significantly longer survival (HR=0.40, P=0.020). The present study examined clinical and biological implications of specific genes and it was concluded that their expression has an impact on the outcome of trastuzumab-treated patients with MBC.

Drug-Induced Resistance and Phenotypic Switch in Triple-Negative Breast Cancer Can Be Controlled via Resolution and Targeting of Individualized Signaling Signatures

Simple Summary

Patients with Triple Negative Breast Cancer (TNBC) have a poor prognosis due to high inter-tumor heterogeneity and absence of effective targeted treatments. Through quantification of ongoing processes in each individual with TNBC, we propose an explanation on why certain previously suggested monotherapies, such as anti-EGFR, are not effective. We experimentally demonstrate that monotherapies or drug combinations that are not adjusted accurately to the patient-specific ongoing processes may create an evolutionary pressure on a tumor leading to the emergence of previously undetected or untargeted cellular subpopulations. We show for example that certain TNBC tumors may benefit from therapies targeting estrogen receptors (ER), similarly to ER positive cancers. When untargeted, those tumors may develop large ER positive subpopulations. We propose that anti-TNBC therapy should be accurately tailored to the personalized molecular processes and that incomplete or “wrong” treatments may generate diverse evolutionary routes of TNBC tumors leading to drug resistance.

Abstract

Triple-negative breast cancer (TNBC) is an aggressive subgroup of breast cancers which is treated mainly with chemotherapy and radiotherapy. Epidermal growth factor receptor (EGFR) was considered to be frequently expressed in TNBC, and therefore was suggested as a therapeutic target. However, clinical trials of EGFR inhibitors have failed. In this study, we examine the relationship between the patient-specific TNBC network structures and possible mechanisms of resistance to anti-EGFR therapy. Using an information-theoretical analysis of 747 breast tumors from the TCGA dataset, we resolved individualized protein network structures, namely patient-specific signaling signatures (PaSSS) for each tumor. Each PaSSS was characterized by a set of 1–4 altered protein–protein subnetworks. Thirty-one percent of TNBC PaSSSs were found to harbor EGFR as a part of the network and were predicted to benefit from anti-EGFR therapy as long as it is combined with anti-estrogen receptor (ER) therapy. Using a series of single-cell experiments, followed by in vivo support, we show that drug combinations which are not tailored accurately to each PaSSS may generate evolutionary pressure in malignancies leading to an expansion of the previously undetected or untargeted subpopulations, such as ER+ populations. This corresponds to the PaSSS-based predictions suggesting to incorporate anti-ER drugs in certain anti-TNBC treatments. These findings highlight the need to tailor anti-TNBC targeted therapy to each PaSSS to prevent diverse evolutions of TNBC tumors and drug resistance development.

Targeted Liposomal Chemotherapies to Treat Triple-Negative Breast Cancer

Simple Summary

Triple-negative breast cancers (TNBCs) are mainly treated with standard chemotherapies. Combined therapies have been demonstrated as a promising treatment strategy in clinics. The aim of this study was to develop a new formulation of combined chemotherapies facilitated with a targeted delivery vehicle. We found that the mertansine and gemcitabine with different anti-cancer mechanisms resulted in high cytotoxicity in TNBC cells. The in vivo evaluations using two TNBC xenograft models confirmed the anti-tumor efficacy, i.e., significantly reduced tumor growth rate. Furthermore, the antibody-tagged liposomes effectively delivered the therapeutic drugs to TNBC tumor, which could reduce the side effects. This study is highly translational and the targeted liposomal drug formulation can be further investigated in future clinical trials for TNBC treatment.

Abstract

Triple-negative breast cancers (TNBCs) are highly aggressive and recurrent. Standard cytotoxic chemotherapies are currently the main treatment options, but their clinical efficacies are limited and patients usually suffer from severe side effects. The goal of this study was to develop and evaluate targeted liposomes-delivered combined chemotherapies to treat TNBCs. Specifically, the IC₅₀ values of the microtubule polymerization inhibitor mertansine (DM1), mitotic spindle assembly defecting taxane (paclitaxel, PTX), DNA synthesis inhibitor gemcitabine (GC), and DNA damage inducer doxorubicin (AC) were tested in both TNBC MDA-MB-231 and MDA-MB-468 cells. Then we constructed the anti-epidermal growth factor receptor (EGFR) monoclonal antibody (mAb) tagged liposomes and confirmed its TNBC cell surface binding using flow cytometry, internalization with confocal laser scanning microscopy, and TNBC xenograft targeting in NSG female mice using In Vivo Imaging System. The safe dosage of anti-EGFR liposomal chemotherapies, i.e., <20% body weight change, was identified. Finally, the in vivo anti-tumor efficacy studies in TNBC cell line-derived xenograft and patient-derived xenograft models revealed that the targeted delivery of chemotherapies (mertansine and gemcitabine) can effectively inhibit tumor growth. This study demonstrated that the targeted liposomes enable the new formulations of combined therapies that improve anti-TNBC efficacy.

PI3K and MAPK Pathways as Targets for Combination with the Pan-HER Irreversible Inhibitor Neratinib in HER2-Positive Breast Cancer and TNBC by Kinome RNAi Screening

Human epidermal growth factor receptor (EGFR) 2 (HER2) is overexpressed/amplified in about 25% of all breast cancers, and EGFR is overexpressed in up to 76% and amplified in up to 24% of triple-negative breast cancers (TNBC). Here, we aimed to identify inhibitors that may enhance the anti-tumor activity of neratinib for HER2+ breast cancer and TNBC. By conducting a non-biased high-throughput RNA interference screening, we identified PI3K/AKT/mTOR and MAPK as two potential inhibitory synergistic canonical pathways. We confirmed that everolimus (mTOR inhibitor) and trametinib (MEK inhibitor) enhances combinatorial anti-proliferative effects with neratinib under anchorage-independent growth conditions (p < 0.05). Compared to single agent neratinib, the combination therapies significantly enhanced tumor growth inhibition in both SUM190 HER2+ breast cancer (neratinib plus everolimus, 77%; neratinib plus trametinib, 77%; p < 0.0001) and SUM149 TNBC (neratinib plus everolimus, 71%; neratinib plus trametinib, 81%; p < 0.0001) xenograft models. Compared to single-agent neratinib, everolimus, or trametinib, both everolimus plus neratinib and trametinib plus neratinib significantly suppressed proliferation marker Ki67 and enhanced antitumor efficacy by activating the apoptosis pathway shown by increased Bim and cleaved-PARP expression. Taken together, our data justify new neratinib-based combinations for both HER2+ breast cancer and TNBC.

In silico analysis of differentially expressed genesets in metastatic breast cancer identifies potential prognostic biomarkers

BACKGROUND

Identification of specific biological functions, pathways, and appropriate prognostic biomarkers is essential to accurately predict the clinical outcomes of and apply efficient treatment for breast cancer patients.

METHODS

To search for metastatic breast cancer-specific biological functions, pathways, and novel biomarkers in breast cancer, gene expression datasets of metastatic breast cancer were obtained from Oncomine, an online data mining platform. Over- and under-expressed genesets were collected and the differentially expressed genes were screened from four datasets with large sample sizes (N > 200). They were analyzed for gene ontology (GO), KEGG pathway, protein-protein interaction, and hub gene analyses using online bioinformatic tools (Enrichr, STRING, and Cytoscape) to find enriched functions and pathways in metastatic breast cancer. To identify novel prognostic biomarkers in breast cancer, differentially expressed genes were screened from the entire twelve datasets with any sample sizes and tested for expression correlation and survival analyses using online tools such as KM plotter and bc-GenExMiner.

RESULTS

Compared to non-metastatic breast cancer, 193 and 144 genes were differentially over- and under-expressed in metastatic breast cancer, respectively, and they were significantly enriched in regulating cell death, epidermal growth factor receptor signaling, and membrane and cytoskeletal structures according to the GO analyses. In addition, genes involved in progesterone- and estrogen-related signalings were enriched according to KEGG pathway analyses. Hub genes were identified via protein-protein interaction network analysis. Moreover, four differentially over-expressed (CCNA2, CENPN, DEPDC1, and TTK) and three differentially under-expressed genes (ABAT, LRIG1, and PGR) were further identified as novel biomarker candidate genes from the entire twelve datasets. Over- and under-expressed biomarker candidate genes were positively and negatively correlated with the aggressive and metastatic nature of breast cancer and were associated with poor and good prognosis of breast cancer patients, respectively.

CONCLUSIONS

Transcriptome datasets of metastatic breast cancer obtained from Oncomine allow the identification of metastatic breast cancer-specific biological functions, pathways, and novel biomarkers to predict clinical outcomes of breast cancer patients. Further functional studies are needed to warrant validation of their roles as functional tumor-promoting or tumor-suppressing genes.

Phenotypic Heterogeneity and Metastasis of Breast Cancer Cells

Although intratumoral genomic heterogeneity can impede cancer research and treatment, less is known about the effects of phenotypic heterogeneities. To investigate the role of cell migration heterogeneities in metastasis, we phenotypically sorted metastatic breast cancer cells into two subpopulations based on migration ability. Although migration is typically considered to be associated with metastasis, when injected orthotopically in vivo, the weakly migratory subpopulation metastasized significantly more than the highly migratory subpopulation. To investigate the mechanism behind this observation, both subpopulations were assessed at each stage of the metastatic cascade, including dissemination from the primary tumor, survival in the circulation, extravasation, and colonization. Although both subpopulations performed each step successfully, weakly migratory cells presented as circulating tumor cell (CTC) clusters in the circulation, suggesting clustering as one potential mechanism behind the increased metastasis of weakly migratory cells. RNA sequencing revealed weakly migratory subpopulations to be more epithelial and highly migratory subpopulations to be more mesenchymal. Depletion of E-cadherin expression from weakly migratory cells abrogated metastasis. Conversely, induction of E-cadherin expression in highly migratory cells increased metastasis. Clinical patient data and blood samples showed that CTC clustering and E-cadherin expression are both associated with worsened patient outcome. This study demonstrates that deconvolving phenotypic heterogeneities can reveal fundamental insights into metastatic progression. More specifically, these results indicate that migratory ability does not necessarily correlate with metastatic potential and that E-cadherin promotes metastasis in phenotypically sorted breast cancer cell subpopulations by enabling CTC clustering. SIGNIFICANCE: This study employs phenotypic cell sorting for migration to reveal a weakly migratory, highly metastatic breast cancer cell subpopulation regulated by E-cadherin, highlighting the dichotomy between cancer cell migration and metastasis.