Breast Tumor Cells Research Articles

Evaluation of the association between centrosome amplification in tumor tissue of breast cancer patients and changes in the expression of CETN1 and CNTROB genes

One of the contributing factors of cancer is the chromosomal aberration caused by centrosome amplification (CA). Changes in the expression of centrosomal genes can cause centrosomal abnormalities. Among the genes involved are CETN1 and CNTROB. Considering the importance and prevalence of breast cancer the aim of this study was to investigate the expression of these genes and its association with CA in breast cancer in women. In this case-control study, 40 breast cancer patients were referred to Mehr hospital selected and invasive breast cancer was confirmed by pathological tests. IHC method was done on paraffin-embedded breast cancer tissue to evaluate centrosome amplification by targeting Pericentrin antibody. Real-time PCR performed to gene expression of CETN1 and CNTROB. The data were analyzed by t-test and ANOVA test. The results showed that CA in breast tumor cells significantly was more than adjacent normal cells (p ≤ 0.05). Results of CETN1 and CNTROB gene expression showed increase expression in tumor tissue compared to control, respectively (p = 0.01, P = 0.02). Our finding showed that alterations of CETN1 and CNTROB gene expression in cancer tissues of patients were excessive in comparison with normal tissues, which could cause cell proliferation, tumor growth and metastasis. It is suggested to find basic strategies for diagnosis and treatment of breast cancer needed more samples of breast cancer, and other genes involved in the function of centrosomes.

Astrocytic laminin-211 drives disseminated breast tumor cell dormancy in brain.

Although dormancy is thought to play a key role in the metastasis of breast tumor cells to the brain, our knowledge of the molecular mechanisms regulating disseminated tumour cell (DTC) dormancy in this organ is limited. Here, using serial intravital imaging of dormant and metastatic triple-negative breast cancer lines, we identify escape from the single-cell or micro-metastatic state as the rate limiting step towards brain metastasis. We show that every DTC occupies a vascular niche, with quiescent DTCs residing on astrocyte endfeet. At these sites, astrocyte-deposited laminin-211 drives DTC quiescence by inducing the dystroglycan receptor to associate with yes-associated protein (YAP), thereby sequestering it from the nucleus and preventing its pro-metastatic functions. These findings identify a brain-specific mechanism of DTC dormancy and highlight the need for a more thorough understanding of tumor dormancy to develop therapeutic approaches that prevent brain metastasis.

Neuronal exposure induces neurotransmitter signaling and synaptic mediators in tumors early in brain metastasis.

Brain metastases (BM) are responsible for neurological decline and poor overall survival. Although the pro-metastatic roles of glial cells, and the acquisition of neuronal attributes in established BM tumors have been described, there are no studies that investigate the initial interplay between neurons and brain-seeking tumor cells. The aim of this study was to characterize early tumor-neuron interactions and the induced CNS-adaptive changes in tumor cells prior to macro-colonization. Utilizing pure neuronal cultures and brain-naïve and patient-derived BM tumor cells, we surveyed the early induction of mediators of neurotransmitter (NT) and synaptic signaling in breast and lung tumor cells. Reliance on microenvironmental GABA in breast-to-brain metastatic cells (BBMs) was assessed in vitro and in vivo. Coculture with neurons induces early expression of classical NT receptor genes (HTR4, GRIA2, GRIN2B, GRM4, GRM8, DRD1) and neuronal synaptic mediators (CNR1, EGR2, ARC, NGFR, NRXN1) in breast and lung cancer cells. NT-dependent classification of tumor cells within the neuronal niche shows breast cancer cells become GABAergic responsive brain metastases (GRBMs) and transition from relying on autocrine GABA, to paracrine GABA from adjacent neurons; while autocrine Dopaminergic breast and lung tumor cells persist. In vivo studies confirm reliance on paracrine GABA is an early CNS-acclimation strategy in breast cancer. Moreover, neuronal contact induces early resurgence in Reelin expression in tumor cells through epigenetic activation, facilitating CNS adaptation. Tumor-neuron interactions allow for CNS adaptation early in the course of brain metastasis.

Green Tea (Camellia sinensis) Extract Induces p53-Mediated Cytotoxicity and Inhibits Migration of Breast Cancer Cells.

Green tea (GT) has been shown to play an important role in cancer chemoprevention. However, the related molecular mechanisms need to be further explored, especially regarding the use of GT extract (GTE) from the food matrix. For this study, epigallocatechin gallate (EGCG) and epigallocatechin (EGC) were identified in GTE, representing 42 and 40% of the total polyphenols, respectively. MDA-MB-231 (p53-p.R280K mutant) and MCF-7 (wild-type p53) breast tumor cells and MCF-10A non-tumoral cells were exposed to GTE for 24–48 h and cell viability was assessed in the presence of p53 inhibitor pifithrin-α. GTE selectively targeted breast tumor cells without cytotoxic effect on non-tumoral cells and p53 inhibition led to an increase in viable cells, especially in MCF-7, suggesting the involvement of p53 in GTE-induced cytotoxicity. GTE was also effective in reducing MCF-7 and MDA-MD-231 cell migration by 30 and 50%, respectively. An increment in p53 and p21 expression stimulated by GTE was observed in MCF-7, and the opposite phenomenon was found in MDA-MB-231 cells, with a redistribution of mutant-p53 from the nucleus and no differences in p21 levels. All these findings provide insights into the action of GTE and support its anticarcinogenic potential on breast tumor cells.

Experimental and Theoretical DFT Study of Cu(I)/N,N-Disubstituted-N'-acylthioureato Anticancer Complexes: Actin Cytoskeleton and Induction of Death by Apoptosis in Triple-Negative Breast Tumor Cells.

Six complexes with the general formula [Cu(acylthioureato)(PPh3)2] were synthesized and characterized using spectroscopic techniques (IR, UV/visible, and 1D and 2D NMR), mass spectrometry, elemental analysis, and X-ray diffraction. Interpretation of the in vitro cytotoxicity data of Cu(I) complexes took into account their stability in cell culture medium. DFT calculations showed that NMR properties, such as the shielding of carbon atoms, are affected by relativistic effects, supported by the ZORA Hamiltonian in the theoretical calculations. Additionally, the calculation of the energies of the frontier molecular orbitals predicted that the structural changes of the acylthiourea ligands did not cause marked changes in the reactivity descriptors. All complexes were cytotoxic to the evaluated tumor cell lines [MDA-MB-231 (triple-negative breast cancer, TNBC), MCF-7 (breast cancer), and A549 (lung cancer)]. In the MDA-MB-231 cell line, complex 1 significantly altered the cytoskeleton of the cells, reducing the density and promoting the condensation of F-actin filaments. In addition, the compound caused an increase in the percentage of cells in the fragmented DNA region (sub-G0) and induced cell death via the apoptotic pathway starting at the IC50 concentration. Taken together, the results show that complex 1 has cytotoxic and apoptotic effects on TNBC cells, which is a cell line originating from an aggressive, difficult-to-treat breast cancer.

A proposal of 3D sensor for rapid detection of breast tumour cell using photonic structure

The present research proposes a method that can identify tumour cells present in the human breast with the help of a plasmon-based three-dimensional (3D) photonic structure. The mechanism of detection of cells (tumour or normal) is realised through the analysis of the photonic bandgap of the proposed copper-based plasmonic structure. Moreover, the plane-wave expansion technique is applied to find the solution of the Helmholtz equation that determines the band structure. In this process, three signals with frequencies of 0.5, 1.0 and 1.5 THz are allowed to impinge on the structure to obtain the required results. The detection of cells that may be normal or suffering from tumour is confirmed by the reflected signal from the 3D photonic structure. More precisely, the bandgap analysis suggests that the cell is cancerous (suffering from tumour) if the reflected signal falls within the blue regime. In contrast, if the signal received finds a place within the violet regime of the spectrum, then this is an indication of a normal cell.

Imiquimod-gemcitabine nanoparticles harness immune cells to suppress breast cancer

Monotherapy with a single chemotherapeutic regimen has met with significant hurdles in terms of clinical efficacy. The complexity of cancer accentuates the need for an alternative approach with a combination of two or more therapeutic regimens to win the battle. However, it is still a challenge to develop a successful combination of drugs with high efficiency and low toxicity to control cancer growth. While gemcitabine monotherapy remains a choice of standard treatment for advanced breast cancer, the approach has not prolonged the median survival time of metastatic breast cancer patients. Here, we report a hyaluronic acid (HA)-based drug combination of gemcitabine (GEM) with imiquimod (IMQ) to stimulate immune cells for anticancer activity. Treatment of the drug combination (IMQ-HA-GEM) showed enhanced anticancer activity against 4T1 breast tumor cells in vitro. Our study with a microfluidics-based 3D, compartmentalized cancer model showed that infiltration of THP-1 monocytes occurred particularly at the site of cancer cells treated with IMQ-HA-GEM. Moreover, IMQ-HA-GEM significantly suppressed the volume of 4T1 breast tumor of mice in vivo. Flow cytometry study displayed a significantly higher activation of CD11b+ immune cells in the blood of mice treated with IMQ-HA-GEM, whereas immunohistochemistry study revealed greater prevalence of CD68+ tumor-associated macrophages in the tumor. Histological examination of isolated tumors of mice treated with IMQ-HA-GEM further confirmed the efficacy of drug combination on cancer cells. This study supports the conclusion that imiquimod potentiates the effect of gemcitabine by activating immune cells to suppress tumors in the form of combination nanoparticles.

To explore immune synergistic function of Quercetin in inhibiting breast cancer cells

BackgroundThe precancerous disease of breast cancer is an inevitable stage in the tumorigenesis and development of breast neoplasms. Quercetin (Que) has shown great potential in breast cancer treatment by inhibiting cell proliferation and regulating T cell function. γδ T cells are a class of nontraditional T cells that have long attracted attention due to their potential in immunotherapy. In this study, we revealed the immunomodulatory function of Que through regulation of the JAK/STAT1 signaling pathway, which was followed by the synergistic killing of breast cancer cells.MethodsIn the experimental design, we first screened target genes with or without Que treatment, and we intersected the Que target with the disease target by functional enrichment analysis. Second, MCF-10A, MCF-10AT, MCF-7 and MDA-MB-231 breast cancer cell lines were treated with Que for 0 h, 24 h and 48 h. Then, we observed the expression of its subsets by coculturing Que and γδ T cells and coculturing Que and γδ T cells with breast tumor cells to investigate their synergistic killing effect on tumor cells. Finally, Western blotting was used to reveal the changes in proteins related to the JAK/STAT1 signaling pathway after Que treatment in MCF-10AT and MCF-7 cells for 48 h.ResultsThe pathway affected by Que treatment was the JAK/STAT1 signaling pathway and was associated with precancerous breast cancer, as shown by network pharmacology analysis. Que induced apoptosis of MCF-10AT, MCF-7 and MDA-MB-231 cells in a time- and concentration-dependent manner (P < 0.05). Most importantly, Que promoted the differentiation of γδ T cells into the Vδ2 T cell subpopulation. The best ratio of effector cells to target cells (E/T) was 10:1, the killing percentages of γδ T cells against MCF-10A, MCF-10AT, MCF-7, and MDA-MB-231 were 61.44 ± 4.70, 55.52 ± 3.10, 53.94 ± 2.74, and 53.28 ± 1.73 (P = 0.114, P = 0.486, and P = 0.343, respectively), and the strongest killing effect on precancerous breast cancer cells and breast cancer cells was found when the Que concentration was 5 μM and the E/T ratio was 10:1 (64.94 ± 3.61, 64.96 ± 5.45, 55.59 ± 5.98, and 59.04 ± 5.67, respectively). In addition, our results showed that Que increased the protein levels of IFNγ-R, p-JAK2 and p-STAT1 while decreasing the protein levels of PD-L1 (P < 0.0001).ConclusionsIn conclusion, Que plays a synergistic role in killing breast cancer cells and promoting apoptosis by regulating the expression of IFNγ-R, p-JAK2, p-STAT1 and PD-L1 in the JAK/STAT1 signaling pathway and promoting the regulation of γδ T cells. Que may be a potential drug for the prevention of precancerous breast cancer and adjuvant treatment of breast cancer.

Design, synthesis, in vitro antiproliferative evaluation and GSK-3β kinase inhibition of a new series of pyrimidin-4-one based amide conjugates

A new series of novel amide conjugates of pyrimidin-4-one and aromatic/heteroaromatic /secondary cyclic amines has been synthesized and their in vitro antiproliferative activities against a panel of 60 human cancer cell lines of nine different cancer types were tested at NCI. Among the synthesized compounds, compound (4i) showed significant anti-proliferative activity. Compound (4i) displayed most potent activity against the breast tumor cell line T-47D and CNS tumor cell line SNB-75 exhibiting a growth of 1.93 % and 14.63 %, respectively. ADMET studies of the synthesized compounds were also performed and they were found to exhibit good drug like properties. Compound (4i) was found to exhibit potential inhibitory effect over GSK-3β with IC50 value of 71 nM. The molecular docking studies revealed that (4i) showed good binding affinity to GSK-3β and revealed multiple H-bonding and p-cation interactions with important amino acid residues on the receptor site. Compound (4i) may thus serve as a potential candidate for further development of novel anticancer therapeutics.

Anti-Tumor Necrosis Factor Receptor 2 Antibody Combined With Anti-PD-L1 Therapy Exerts Robust Antitumor Effects in Breast Cancer.

Breast cancer is a leading type of malignant tumor in women; however, the immunotherapy in breast cancer is still underappreciated. In this study, we demonstrated that tumor necrosis factor receptor 2 (TNFR2) is highly expressed in both breast tumor tissue and tumor-infiltrating immunosuppressive CD4+Foxp3+ regulatory T cells (Tregs). We found that TNFR2 antagonistic antibody reduced Foxp3 expression and the proliferation of Tregs and impaired the inhibitory effect of Tregs on CD4+CD25– effector T (Teff) cells in a dose-dependent manner. The treatment of anti-TNFR2 antibody not only inhibited the proliferation of breast tumor cells in vitro but also suppressed the tumorigenesis of murine mammary carcinoma 4T1 cells in vivo. Mice recovered from tumor growth also developed 4T1-specific immunity. Furthermore, we demonstrated that anti-TNFR2 antibody in combination with anti-PD-L1 exhibited augmented antitumor effects than monotherapy. Anti-TNFR2 treatment also tended to increase the expression of proinflammatory cytokines in tumor tissues. In conclusion, our study suggests that TNFR2 antagonist could potentially offer a clinical benefit as a single agent or in combination with immune checkpoint blockade treatment for breast cancer immunotherapy.

Periostin gene expression in neu-positive breast cancer cells is regulated by a FGFR signaling cross talk with TGF\u03b2/PI3K/AKT pathways

BackgroundBreast cancer is a highly heterogeneous disease with multiple drivers and complex regulatory networks. Periostin (Postn) is a matricellular protein involved in a plethora of cancer types and other diseases. Postn has been shown to be involved in various processes of tumor development, such as angiogenesis, invasion, cell survival and metastasis. The expression of Postn in breast cancer cells has been correlated with a more aggressive phenotype. Despite extensive research, it remains unclear how epithelial cancer cells regulate Postn expression.MethodsUsing murine tumor models and human TMAs, we have assessed the proportion of tumor samples that have acquired Postn expression in tumor cells. Using biochemical approaches and tumor cell lines derived from Neu+ murine primary tumors, we have identified major regulators of Postn gene expression in breast cancer cell lines.ResultsHere, we show that, while the stromal compartment typically always expresses Postn, about 50% of breast tumors acquire Postn expression in the epithelial tumor cells. Furthermore, using an in vitro model, we show a cross-regulation between FGFR, TGFβ and PI3K/AKT pathways to regulate Postn expression. In HER2-positive murine breast cancer cells, we found that basic FGF can repress Postn expression through a PKC-dependent pathway, while TGFβ can induce Postn expression in a SMAD-independent manner. Postn induction following the removal of the FGF-suppressive signal is dependent on PI3K/AKT signaling.ConclusionOverall, these results reveal a novel regulatory mechanism and shed light on how breast tumor cells acquire Postn expression. This complex regulation is likely to be cell type and cancer specific as well as have important therapeutic implications.

Agaricus bisporus β-(1 → 6)-d-glucan induces M1 phenotype on macrophages and increases sensitivity to doxorubicin of triple negative breast cancer cells

Mushroom β-d-glucans have demonstrated immunomodulatory activity, which is initiated by their recognition by specific receptors on immune system cells surfaces. Studies indicated that β-d-glucans may present a synergistic effect with chemotherapy drugs. In this study, a linear β-(1 → 6)-d-glucan (B16), isolated from A. bisporus and previously characterized (Mw: 8.26 × 104 g/mol), was evaluated about its capacity to modulate THP-1 macrophages towards an M1 phenotype and induce an antitumoral activity. This was evidenced by the production of pro-inflammatory markers upon B16 treatment (30; 100 μg/mL). The breast tumor cells (MDA-MB-231) viability was not affected by treatment with B16, however, their viability markedly decreased upon treatment with the drug doxorubicin. The results showed a synergic effect of B16 and doxorubicin, which reduced the viability of MDA-MB-231 cells by 31%. Furthermore, B16 treatment provided a sustainable M1 state environment and contributed to increase the sensitivity of breast cancer cells to the doxorubicin treatment.

Spatial and temporal dynamics of RhoA activities of single breast tumor cells in a 3D environment revealed by a machine learning-assisted FRET technique

One of the hallmarks of cancer cells is their exceptional ability to migrate within the extracellular matrix (ECM) for gaining access to the circulatory system, a critical step of cancer metastasis. RhoA, a small GTPase, is known to be a key molecular switch that toggles between actomyosin contractility and lamellipodial protrusion during cell migration. Current understanding of RhoA activity in cell migration has been largely derived from studies of cells plated on a two-dimensional (2D) substrate using a FRET biosensor. There has been increasing evidence that cells behave differently in a more physiologically relevant three-dimensional (3D) environment. However, studies of RhoA activities in 3D have been hindered by low signal-to-noise ratio in fluorescence imaging. In this paper, we present a a machine learning-assisted FRET technique to follow the spatiotemporal dynamics of RhoA activities of single breast tumor cells (MDA-MB-231) migrating in a 3D as well as a 2D environment. We found that RhoA activity is more polarized along the long axis of the cell for single cells migrating on 2D fibronectin-coated glass versus those embedded in 3D collagen matrices. In particular, RhoA activities of cells in 2D exhibit a distinct front-to-back and back-to-front movement during migration in contrast to those in 3D. Finally, regardless of dimensionality, RhoA polarization is found to be moderately correlated with cell shape.

CTI-2 Inhibits Metastasis and Epithelial-Mesenchymal Transition of Breast Cancer Cells by Modulating MAPK Signaling Pathway.

Although some breast cancer patients die due to tumor metastasis rather than from the primary tumor, the molecular mechanism of metastasis remains unclear. Therefore, it is necessary to inhibit breast cancer metastasis during cancer treatment. In this case, after designing and synthesizing CTI-2, we found that CTI-2 treatment significantly reduced breast cancer cell metastasis in vivo and in vitro. Notably, with the treatment of CTI-2 in breast cancer cells, the expression level of E-cadherin increased, while the expression level of N-cadherin and vimentin decreased. In addition, after CTI-2 treatment, those outflow levels for p-ERK, p-p38, and p-JNK diminished, while no significant changes in the expression levels of ERK, JNK, or p38 were observed. Our conclusion suggested that CTI-2 inhibits the epithelial-mesenchymal transition (EMT) of breast carcinoma cells by inhibiting the activation of the mitogen-activated protein kinase (MAPK) signaling pathway, thereby inhibiting the metastasis of breast tumor cells. Therefore, we believe that CTI-2 is another candidate for breast tumor medication.

Metabolomics-Microbiome Crosstalk in the Breast Cancer Microenvironment.

Breast cancer, the most frequent cancer diagnosed among females, is associated with a high mortality rate worldwide. Alterations in the microbiota have been linked with breast cancer development, suggesting the possibility of discovering disease biomarkers. Metabolomics has emerged as an advanced promising analytical approach for profiling metabolic features associated with breast cancer subtypes, disease progression, and response to treatment. The microenvironment compromises non-cancerous cells such as fibroblasts and influences cancer progression with apparent phenotypes. This review discusses the role of metabolomics in studying metabolic dysregulation in breast cancer caused by the effect of the tumor microenvironment on multiple cells such as immune cells, fibroblasts, adipocytes, etc. Breast tumor cells have a unique metabolic profile through the elevation of glycolysis and the tricarboxylic acid cycle metabolism. This metabolic profile is highly sensitive to microbiota activity in the breast tissue microenvironment. Metabolomics shows great potential as a tool for monitoring metabolic dysregulation in tissue and associating the findings with microbiome expression.

Synthesis, crystal structure, DFT and anticancer study of dihydroartermisinin-paracetamol hybrids

A pair of C-10 epimers of dihydroartermisinin-paracetamol hybrids (A and B) were prepared in this work, and both of which were characterized by MS, 1H NMR, 13C NMR, IR and ECD spectra as well as by a single crystal X-ray structural analysis. Subsequently, the structures of the two compounds were analyzed with DFT-based approaches. The analytical results on conformations indicated that the DFT-optimized molecular structures were consistent with the crystal structures confirmed by X-ray diffraction. The packing of the molecules in the solid state was stabilized by hydrogen bonds. The signs of the experimental IR and ECD spectra was also efficiently simulated by the DFT methods. A primary evaluation on anticancer effects of A and B was conducted towards human breast tumor cell line MCF-7 and human colon tumor cell line HCT116, the results demonstrated that 10-α-O-(4-acetylamino) phenyl dihydroartemisinin (A) was slightly less potent than its 10-β counterpart (B) in both tested cell lines.

Triple Targeting of Breast Tumors Driven by Hormonal Receptors and HER2.

Breast cancers that express hormonal receptors (HR) and HER2 display resistance to targeted therapy. Tumor-promotional signaling from the HER2 and estrogen receptor (ER) pathways converges at the cyclin D1 and cyclin-dependent kinases (CDK) 4 and 6 complex, which drives cell-cycle progression and development of therapeutic resistance. Therefore, we hypothesized that co-targeting of ER, HER2, and CDK4/6 may result in improved tumoricidal activity and suppress drug-resistant subclones that arise on therapy. We tested the activity of the triple targeted combination therapy with tucatinib (HER2 small-molecule inhibitor), palbociclib (CKD4/6 inhibitor), and fulvestrant (selective ER degrader) in HR+/HER2+ human breast tumor cell lines and xenograft models. In addition, we evaluated whether triple targeted combination prevents growth of tucatinib or palbociclib-resistant subclones in vitro and in vivo Triple targeted combination significantly reduced HR+/HER2+ tumor cell viability, clonogenic survival, and in vivo growth. Moreover, survival of HR+/HER2+ cells that were resistant to the third drug in the regimen was reduced by the other two drugs in combination. We propose that a targeted triple combination approach will be clinically effective in the treatment of otherwise drug-resistant tumors, inducing robust responses in patients.

An organoid-based screen for epigenetic inhibitors that stimulate antigen presentation and potentiate T-cell-mediated cytotoxicity.

In breast cancer, genetic heterogeneity, the lack of actionable targets, and immune evasion all contribute to the limited clinical response rates to immune checkpoint blockade therapy. Here, we report a high-throughput screen based on the functional interaction of mouse or patient-derived breast tumour organoids and tumour-specific cytotoxic T cells for the identification of epigenetic inhibitors that promote antigen presentation and that potentiate T-cell-mediated cytotoxicity. We show that the epigenetic inhibitors GSK-LSD1, CUDC-101 and BML-210, identified by the screen, display antitumour activities in orthotopic mammary tumours in mice, that they upregulate antigen presentation mediated by the major histocompatibility complex class I on breast tumour cells, and that treatment with BML-210 substantially sensitized breast tumours to the checkpoint inhibitor programmed-death-1. Standardized measurements of tumour-cell killing activity facilitated by tumour-organoid–T cell screens may aid the identification of candidate immunotherapeutics for a range of cancers.

Novel role of the dietary flavonoid fisetin in suppressing rRNA biogenesis

The nucleolus of a cell is a critical cellular compartment that is responsible for ribosome biogenesis and plays a central role in tumor progression. Fisetin, a nutraceutical, is a naturally occurring flavonol from the flavonoid group of polyphenols that has anti-cancer effects. Fisetin negatively impacts several signaling pathways that support tumor progression. However, effect of fisetin on the nucleolus and its functions were unknown. We observed that fisetin is able to physically enter the nucleolus. In the nucleolus, RNA polymerase I (RNA Pol I) mediates the biogenesis of ribosomal RNA. Thus, we investigated the impacts of fisetin on the nucleolus. We observed that breast tumor cells treated with fisetin show a 20–30% decreased nucleolar abundance per cell and a 30–60% downregulation of RNA Pol I transcription activity, as well as a 50–70% reduction in nascent rRNA synthesis, depending on the cell line. Our studies show that fisetin negatively influences MAPK/ERK pathway to impair RNA Pol I activity and rRNA biogenesis. Functionally, we demonstrate that fisetin acts synergistically (CI = 0.4) with RNA Pol I inhibitor, BMH-21 and shows a noteworthy negative impact (60% decrease) on lung colonization of breast cancer cells. Overall, our findings highlight the potential of ribosomal RNA (rRNA) biogenesis as a target for secondary prevention and possible treatment of metastatic disease.Fisetin, a natural flavanol, can localize to the nucleolus and decrease rRNA biogenesis. It preferentially targets tumorigenic cells and cells with cancer stem-like properties. In combination with the RNA Pol I inhibitor BMH-21, it synergistically inhibits pulmonary metastasis, making this combination an exciting potential therapeutic strategy.

Adipocyte-derived extracellular vesicles promote breast cancer cell malignancy through HIF-1α activity.

Extracellular vesicles (EVs) are emerging key protagonists in intercellular communication between adipocytes and breast cancer (BC) cells. Here, we described a new mechanism by which EVs released by mature adipocytes promoted breast cancer cell malignancy "in vitro" and "in vivo". We found that adipocyte-derived EVs enhanced growth, motility and invasion, stem cell-like properties, as well as specific traits of epithelial-to-mesenchymal transition in both estrogen receptor positive and triple negative BC cells. Of note, adipocyte-derived EVs aid breast tumor cells in lung metastatic colonization after tail-vein injection in mice. These EV-mediated effects occur via the induction of HIF-1α activity, since they were abrogated by the use of the HIF-1α inhibitor KC7F2 or in cells silenced for HIF-1α expression. Moreover, using an "ex vivo" model of obese adipocytes we found that the depletion of EVs counteracted the ability of obese adipocytes to sustain pro-invasive phenotype in BC cells. Interestingly, EVs released by undifferentiated adipocytes failed to induce aggressiveness and HIF-1α expression. These findings shed new light on the role of adipocyte-derived EVs in breast cancer progression, suggesting the possibility to target HIF-1α activity to block the harmful adipocyte-tumor cell dialogue, especially in obese settings.