Deubiquitinating enzyme OTUD4 regulates metastasis in triple-negative breast cancer by stabilizing Snail1.

Metastasis is the primary cause of cancer-related deaths and remains poorly understood. Deubiquitinase OTU domain containing 4 (OTUD4) has been reported to regulate antiviral immune responses and resistance to radio- or chemo-therapies in certain cancers. However, the role of OTUD4 in cancer metastasis remain unknown. Here, we demonstrate that the depletion of OTUD4 in triple-negative breast cancer (TNBC) cells markedly suppress cell clonogenic ability, migration, invasion and cancer stem cell population in vitro as well as metastasis in vivo. Mechanistically, the tumor promoting function of OTUD4 is mainly mediated by deuiquitinating and stabilizing Snail1, one key transcriptional factor in the epithelial-mesenchymal transition. The inhibitory effect of targeting OTUD4 could be largely reversed by the reconstitution of Snail1 in OTUD4-deficient cells. Overall, our study establishes the OTUD4-Snail1 axis as an important regulatory mechanism of breast cancer metastasis and provides a rationale for potential therapeutic interventions in the treatment of TNBC.

Targeted MDM2 Degradation Reveals a New Vulnerability for p53-Inactivated Triple-Negative Breast Cancer.

Triple-negative breast cancers (TNBC) frequently inactivate p53, increasing their aggressiveness and therapy resistance. We identified an unexpected protein vulnerability in p53-inactivated TNBC and designed a new PROteolysis TArgeting Chimera (PROTAC) to target it. Our PROTAC selectively targets MDM2 for proteasome-mediated degradation with high-affinity binding and VHL recruitment. MDM2 loss in p53 mutant/deleted TNBC cells in two-dimensional/three-dimensional culture and TNBC patient explants, including relapsed tumors, causes apoptosis while sparing normal cells. Our MDM2-PROTAC is stable in vivo, and treatment of TNBC xenograft-bearing mice demonstrates tumor on-target efficacy with no toxicity to normal cells, significantly extending survival. Transcriptomic analyses revealed upregulation of p53 family target genes. Investigations showed activation and a required role for TAp73 to mediate MDM2-PROTAC-induced apoptosis. Our data, challenging the current MDM2/p53 paradigm, show MDM2 is required for p53-inactivated TNBC cell survival, and PROTAC-targeted MDM2 degradation is an innovative potential therapeutic strategy for TNBC and superior to existing MDM2 inhibitors. SIGNIFICANCE: p53-inactivated TNBC is an aggressive, therapy-resistant, and lethal breast cancer subtype. We designed a new compound targeting an unexpected vulnerability we identified in TNBC. Our MDM2-targeted degrader kills p53-inactivated TNBC cells, highlighting the requirement for MDM2 in TNBC cell survival and as a new therapeutic target for this disease. See related commentary by Peuget and Selivanova, p. 1043. This article is highlighted in the In This Issue feature, p. 1027.

Presence of human breast cancer xenograft changes the diurnal profile of amino acids in mice.

Human xenografts are extremely useful models to study the biology of human cancers and the effects of novel potential therapies. Deregulation of metabolism, including changes in amino acids (AAs), is a common characteristic of many human neoplasms. Plasma AAs undergo daily variations, driven by circadian endogenous and exogenous factors. We compared AAs concentration in triple negative breast cancer MDA-MB-231 cells and MCF10A non-tumorigenic immortalized breast epithelial cells. We also measured plasma AAs in mice bearing xenograft MDA-MB-231 and compared their levels with non-tumor-bearing control animals over 24 h. In vitro studies revealed that most of AAs were significantly different in MDA-MB-231 cells when compared with MCF10A. Plasma concentrations of 15 AAs were higher in cancer cells, two were lower and four were observed to shift across 24 h. In the in vivo setting, analysis showed that 12 out of 20 AAs varied significantly between tumor-bearing and non-tumor bearing mice. Noticeably, these metabolites peaked in the dark phase in non-tumor bearing mice, which corresponds to the active time of these animals. Conversely, in tumor-bearing mice, the peak time occurred during the light phase. In the early period of the light phase, these AAs were significantly higher in tumor-bearing animals, yet significantly lower in the middle of the light phase when compared with controls. This pilot study highlights the importance of well controlled experiments in studies involving plasma AAs in human breast cancer xenografts, in addition to emphasizing the need for more precise examination of exometabolomic changes using multiple time points.

Cancer­associated fibroblast­derived LRRC15 promotes the migration and invasion of triple­negative breast cancer cells via Wnt/ß­catenin signalling pathway regulation.

Triple­negative breast cancer (TNBC) is a highly aggressive tumour subtype associated with poor prognosis. The function of leucine­rich repeat­containing protein 15 (LRRC15), a member of the leucine­rich repeat superfamily, in TNBC has not yet been elucidated. The aim of this study was to identify the combined role of LRRC15 and Wnt/ß­catenin signalling pathway in the development of TNBC. The expression of LRRC15 in TNBC tissues was analysed using data from The Cancer Genome Atlas. Cell migration and invasion assays were conducted to study the function of LRRC15 in TNBC. The expression of Wnt/ß­catenin signalling proteins was analysed via western blotting. The effect of LRRC15 on ß­catenin nuclear localisation was measured by performing western blotting and luciferase assays. It was found that high LRRC15 expression was associated with poor prognosis in patients with TNBC. High expression of LRRC15 in cancer­associated fibroblasts (CAFs) promoted cell migration and invasion in TNBC cells. In addition, TNBC cells with LRRC15 overexpression in CAFs showed an aberrant increase in ß­catenin activity concomitant with nuclear localisation of ß­catenin, which inhibited its degradation. These results showed that LRRC15 promoted tumour migration and invasion in TNBC cells by regulating the Wnt/ß­catenin signalling pathway.

Concomitant activation of GLI1 and Notch1 contributes to racial disparity of human triple negative breast cancer progression.

Mortality from triple negative breast cancer (TNBC) is significantly higher in African American (AA) women compared to White American (WA) women emphasizing ethnicity as a major risk factor; however, the molecular determinants that drive aggressive progression of AA-TNBC remain elusive. Here, we demonstrate for the first time that AA-TNBC cells are inherently aggressive, exhibiting elevated growth, migration, and cancer stem-like phenotype compared to WA-TNBC cells. Meta-analysis of RNA-sequencing data of multiple AA- and WA-TNBC cell lines shows enrichment of GLI1 and Notch1 pathways in AA-TNBC cells. Enrichment of GLI1 and Notch1 pathway genes was observed in AA-TNBC. In line with this observation, analysis of TCGA dataset reveals a positive correlation between GLI1 and Notch1 in AA-TNBC and a negative correlation in WA-TNBC. Increased nuclear localization and interaction between GLI1 and Notch1 is observed in AA-TNBC cells. Of importance, inhibition of GLI1 and Notch1 synergistically improves the efficacy of chemotherapy in AA-TNBC cells. Combined treatment of AA-TNBC-derived tumors with GANT61, DAPT, and doxorubicin/carboplatin results in significant tumor regression, and tumor-dissociated cells show mitigated migration, invasion, mammosphere formation, and CD44+/CD24- population. Indeed, secondary tumors derived from triple-therapy-treated AA-TNBC tumors show diminished stem-like phenotype. Finally, we show that TNBC tumors from AA women express significantly higher level of GLI1 and Notch1 expression in comparison to TNBC tumors from WA women. This work sheds light on the racial disparity in TNBC, implicates the GLI1 and Notch1 axis as its functional mediators, and proposes a triple-combination therapy that can prove beneficial for AA-TNBC.

Ginsenoside Rh1 Prevents Migration and Invasion through Mitochondrial ROS-Mediated Inhibition of STAT3/NF-κB Signaling in MDA-MB-231 Cells.

Breast cancer (BC) a very common cancer in women worldwide. Triple negative breast cancer (TNBC) has been shown to have a poor prognosis with a high level of tumor metastatic spread. Here, the inhibitory effects of ginsenoside-Rh1 (Rh1) on BC metastasis, and its underlying signaling pathway in TNBC were investigated. Rh1-treated MDA-MB-231 cells were analyzed for metastasis using a wound healing assay, transwell migration and invasion assay, western blotting, and qRT-PCR. Rh1 treatment significantly inhibited BC metastasis by inhibiting the both protein and mRNA levels of MMP2, MMP9, and VEGF-A. Further, Rh1-mediated inhibitory effect on BC migration was associated with mitochondrial ROS generation. Rh1 treatment significantly eliminated STAT3 phosphorylation and NF-κB transactivation to downregulate metastatic factors, such as MMP2, MMP9, and VEGF-A. In addition, Mito-TEMPO treatment reversed Rh1 effects on the activation of STAT3, NF-κB, and their transcriptional targets. Rh1 further enhanced the inhibitory effects of STAT3 or NF-κB specific inhibitor, stattic or BAY 11-7082 on MMP2, MMP9, and VEGF-A expression, respectively. In summary, our results revealed the potent anticancer effect of Rh1 on TNBC migration and invasion through mtROS-mediated inhibition of STAT3 and NF-κB signaling.

Neighbor-enhanced diffusivity in dense, cohesive cell populations.

The dispersal or mixing of cells within cellular tissue is a crucial property for diverse biological processes, ranging from morphogenesis, immune action, to tumor metastasis. With the phenomenon of 'contact inhibition of locomotion,' it is puzzling how cells achieve such processes within a densely packed cohesive population. Here we demonstrate that a proper degree of cell-cell adhesiveness can, intriguingly, enhance the super-diffusive nature of individual cells. We systematically characterize the migration trajectories of crawling MDA-MB-231 cell lines, while they are in several different clustering modes, including freely crawling singles, cohesive doublets of two cells, quadruplets, and confluent population on two-dimensional substrate. Following data analysis and computer simulation of a simple cellular Potts model, which faithfully recapitulated all key experimental observations such as enhanced diffusivity as well as periodic rotation of cell-doublets and cell-quadruplets with mixing events, we found that proper combination of active self-propelling force and cell-cell adhesion is sufficient for generating the observed phenomena. Additionally, we found that tuning parameters for these two factors covers a variety of different collective dynamic states.

Machine learning reveals mesenchymal breast carcinoma cell adaptation in response to matrix stiffness.

Epithelial-mesenchymal transition (EMT) and its reverse process, mesenchymal-epithelial transition (MET), are believed to play key roles in facilitating the metastatic cascade. Metastatic lesions often exhibit a similar epithelial-like state to that of the primary tumour, in particular, by forming carcinoma cell clusters via E-cadherin-mediated junctional complexes. However, the factors enabling mesenchymal-like micrometastatic cells to resume growth and reacquire an epithelial phenotype in the target organ microenvironment remain elusive. In this study, we developed a workflow using image-based cell profiling and machine learning to examine morphological, contextual and molecular states of individual breast carcinoma cells (MDA-MB-231). MDA-MB-231 heterogeneous response to the host organ microenvironment was modelled by substrates with controllable stiffness varying from 0.2kPa (soft tissues) to 64kPa (bone tissues). We identified 3 distinct morphological cell types (morphs) varying from compact round-shaped to flattened irregular-shaped cells with lamellipodia, predominantly populating 2-kPa and >16kPa substrates, respectively. These observations were accompanied by significant changes in E-cadherin and vimentin expression. Furthermore, we demonstrate that the bone-mimicking substrate (64kPa) induced multicellular cluster formation accompanied by E-cadherin cell surface localisation. MDA-MB-231 cells responded to different substrate stiffness by morphological adaptation, changes in proliferation rate and cytoskeleton markers, and cluster formation on bone-mimicking substrate. Our results suggest that the stiffest microenvironment can induce MET.

S100A4 Is Involved in Stimulatory Effects Elicited by the FGF2/FGFR1 Signaling Pathway in Triple-Negative Breast Cancer (TNBC) Cells.

Triple-negative breast cancer (TNBC) is an aggressive breast tumor subtype characterized by poor clinical outcome. In recent years, numerous advancements have been made to better understand the biological landscape of TNBC, though appropriate targets still remain to be determined. In the present study, we have determined that the expression levels of FGF2 and S100A4 are higher in TNBC with respect to non-TNBC patients when analyzing "The Invasive Breast Cancer Cohort of The Cancer Genome Atlas" (TCGA) dataset. In addition, we have found that the gene expression of FGF2 is positively correlated with S100A4 in TNBC samples. Performing quantitative PCR, Western blot, CRISPR/Cas9 genome editing, promoter studies, immunofluorescence analysis, subcellular fractionation studies, and ChIP assays, we have also demonstrated that FGF2 induces in TNBC cells the upregulation and secretion of S100A4 via FGFR1, along with the ERK1/2-AKT-c-Rel transduction signaling. Using conditioned medium from TNBC cells stimulated with FGF2, we have also ascertained that the paracrine activation of the S100A4/RAGE pathway triggers angiogenic effects in vascular endothelial cells (HUVECs) and promotes the migration of cancer-associated fibroblasts (CAFs). Collectively, our data provide novel insights into the action of the FGF2/FGFR1 axis through S100A4 toward stimulatory effects elicited in TNBC cells.

Ferroptotic cell death triggered by conjugated linolenic acids is mediated by ACSL1.

Ferroptosis is associated with lipid hydroperoxides generated by the oxidation of polyunsaturated acyl chains. Lipid hydroperoxides are reduced by glutathione peroxidase 4 (GPX4) and GPX4 inhibitors induce ferroptosis. However, the therapeutic potential of triggering ferroptosis in cancer cells with polyunsaturated fatty acids is unknown. Here, we identify conjugated linoleates including α-eleostearic acid (αESA) as ferroptosis inducers. αESA does not alter GPX4 activity but is incorporated into cellular lipids and promotes lipid peroxidation and cell death in diverse cancer cell types. αESA-triggered death is mediated by acyl-CoA synthetase long-chain isoform 1, which promotes αESA incorporation into neutral lipids including triacylglycerols. Interfering with triacylglycerol biosynthesis suppresses ferroptosis triggered by αESA but not by GPX4 inhibition. Oral administration of tung oil, naturally rich in αESA, to mice limits tumor growth and metastasis with transcriptional changes consistent with ferroptosis. Overall, these findings illuminate a potential approach to ferroptosis, complementary to GPX4 inhibition.

Receptor-type protein tyrosine phosphatase alpha (PTPα) mediates MMP14 localization and facilitates triple-negative breast cancer cell invasion.

The ability of cancer cells to invade surrounding tissues requires degradation of the extracellular matrix (ECM). Invasive structures, such as invadopodia, form on the plasma membranes of cancer cells and secrete ECM-degrading proteases that play crucial roles in cancer cell invasion. We have previously shown that the protein tyrosine phosphatase alpha (PTPα) regulates focal adhesion formation and migration of normal cells. Here we report a novel role for PTPα in promoting triple-negative breast cancer cell invasion in vitro and in vivo. We show that PTPα knockdown reduces ECM degradation and cellular invasion of MDA-MB-231 cells through Matrigel. PTPα is not a component of TKS5-positive structures resembling invadopodia; rather, PTPα localizes with endosomal structures positive for MMP14, caveolin-1, and early endosome antigen 1. Furthermore, PTPα regulates MMP14 localization to plasma membrane protrusions, suggesting a role for PTPα in intracellular trafficking of MMP14. Importantly, we show that orthotopic MDA-MB-231 tumors depleted in PTPα exhibit reduced invasion into the surrounding mammary fat pad. These findings suggest a novel role for PTPα in regulating the invasion of triple-negative breast cancer cells.

Sphingomyelin synthase 2 facilitates M2-like macrophage polarization and tumor progression in a mouse model of triple-negative breast cancer.

High infiltration of M2-polarized macrophages in the primary tumor indicates unfavorable prognosis and poor overall survival in the patients with triple-negative breast cancer (TNBC). Thus, reversing M2-polarized tumor-associated macrophages in the tumors has been considered as a potential therapeutic strategy for TNBC. Sphingomyelin synthase 2 (SMS2) is the key enzyme for sphingomyelin production, which plays an important role in plasma membrane integrity and function. In this study we investigated whether SMS2 inhibitor or SMS2 gene knockout could reduce macrophages M2 polarization and tumor progression in a mouse model of TNBC. We showed that SMS2 mRNA expression was linked to immunosuppressive tumor microenvironment and poor prognosis in TNBC patients. The knockout of SMS2 or application of 15w (a specific SMS2 inhibitor) markedly decreased the generation of M2-type macrophages in vitro, and reduced the tumor weight and lung metastatic niche formation in a 4T1-TNBC mouse model. We further demonstrated that the in vivo antitumor efficacy of 15w was accompanied by a multifaceted remodeling of tumor immune environment reflecting not only the suppression of M2-type macrophages but also diminished levels of regulatory T cells and myeloid-derived suppressor cells leading to a dramatically improved infiltration of antitumor CD8+ T lymphocytes. Collectively, our results reveal a novel and important role of SMS2 in the protumorigenic function and may offer a new strategy for macrophage-targeted anticancer therapy.

Peptidomic analysis of pilose antler and its inhibitory effect on triple-negative breast cancer at multiple sites.

Pilose antler (PA) is a traditional Chinese functional food that has been reported to inhibit breast cancer; however, the specific substances that exert this effect and the underlying mechanisms remain unknown. This study aims to identify the specific proteins in PA water-soluble polypeptides (PAWPs) that are involved in cancer inhibition and determine the effects of PAWPs on triple-negative breast cancer in mice. In this study, peptidomic analysis of 105 varieties of polypeptides from PAWPs was carried out using LC-MS, 22 of which had functions that could potentially suppress tumors, including endopeptidase inhibitors, metal ion-binding proteins, angiogenesis inhibitors, intercellular adhesion proteins, and extracellular matrix repair proteins. Furthermore, we showed that intragastric administration of PAWPs into mice inhibited the growth and metastasis of triple-negative 4T1 breast tumors. PAWPs activated the expression of cleaved-caspase3 and increased tumor apoptosis, resulting in the reduction of platelet-endothelial cell adhesion molecule (PECAM-1/CD31) expression and the number of blood vessels, as well as the inhibition of matrix metalloproteinase (MMP) 2 and 9, increasing the ratio of Cadherin-1 (CDH1)/Cadherin-2 (CDH2) and inhibiting epithelial-mesenchymal transition (EMT) in these tumors. Therefore, PAWPs inhibit the progression and metastasis of triple-negative 4T1 breast cancer at multiple key sites in mice and contain various tumor suppressor proteins that are potentially involved in these processes.

Inhibition of lovastatin- and docosahexaenoic acid-initiated autophagy in triple negative breast cancer reverted resistance and enhanced cytotoxicity.

AIMS: Autophagy plays a complex role in breast cancer by suppressing or improving the efficiency of treatment. Triple-negative breast cancer (TNBC) cell line (MDA-MB-231) is associated with aggressive response and developing therapy resistance. MDA-MB-231 cells depend on autophagy for survival. Also, the potential benefits of autophagy inhibition in ameliorating developed chemotherapy resistance towards MDA-MB-231 remains to be elucidated. Despite showing anti-tumorigenic activities, the use of lovastatin and docosahexaenoic acid (DHA) for treating different types of cancers is still limited. We aimed to investigate the protective effect of autophagy inhibition by chloroquine (CQ) in MDA-MB-231 cells resistance treated with lovastatin or DHA. MAIN METHODS: MDA-MB-231 cells were treated with 30 µM lovastatin and/or 100 µM DHA for 48 h plus 20 µM CQ. Autophagic flux was assessed in association with the expression of multidrug resistance gene 1 (MDR1), transforming growth factor beta 1 gene (TGF-ß1), and autophagy-related 7 gene (ATG7). KEY FINDINGS: Both drugs exhibited dose-dependent cytotoxicity, enhanced the autophagic flux represented by increased LC3BII protein concentration and decreased p62 protein concentration, and up-regulated the expression of MDR1, TGF-ß1, and ATG7 genes. CQ addition enhanced the cytotoxicity of drugs and inhibited the autophagic flux which is detected by higher levels of LC3BII and p62 correlated with the reverted MDR1, TGF-ß1 and ATG7 genes expression. SIGNIFICANCE: Autophagy inhibition by CQ showed an ameliorative effect on lovastatin- and DHA-induced resistance and enhanced their cytotoxicity, providing a promising strategy in breast cancer therapy.

Analysis of the StoRM cohort reveals physical activity to be associated with survival in metastatic breast cancer.

Benefits of physical activity are widely demonstrated for early stage cancers but few studies have focused on metastatic disease. The purpose of this study was to determine the impact of physical activity on survival in patients with metastatic breast cancer. We conducted a secondary analysis of the national, multicentric, non-randomized, prospective cohort SNPs to Risk of Metastasis (StoRM) study. The level of physical activity was self-reported at inclusion and divided into three categories of physical activity: light level, moderate level, and vigorous level. Overall, 833 patients (56.2%) completed the physical activity questionnaire at baseline on average physical activity during the previous year: 11.6% had a light level of physical activity, 69.0% achieved moderate levels of physical activity and 19.3% reported vigorous levels of physical activity. After adjustment for confounding, physical activity was not statistically significantly associated with overall survival in the whole population. Subgroup analysis identified that both vigorous and moderate physical activity were associated with statistically significantly improved overall survival compared to light physical activity level only in the HER2 positive subgroup (HR 0.23; 95% CI 0.07-0.70, p = 0.01 and HR 0.38; 95% CI 0.15-0.96, p = 0.04). Physical activity done during the previous year was associated with survival in HER2 positive metastatic breast cancer patients. These results suggest that overall survival in metastatic breast cancer patients could be improved through physical activity which should be considered as a complementary intervention for these individuals. The study showed that moderate/vigorous levels of physical activity were associated with better overall survival, and that these associations remained statistically significant in multivariate analysis in the HER2 positive subgroup. These results have clinical relevance and justify the recommendations for physical activity interventions in metastatic breast cancer.

Combination of sirtuin 3 and hyperoxia diminishes tumorigenic properties of MDA-MB-231 cells.

AIMS: Since the role of the major mitochondrial NAD+-dependent deacetylase, sirtuin 3 (Sirt3), is differential in cancer, opposite to the well-known tumor-suppressing effect of hyperoxia, this study aimed to investigate the role of Sirt3 in triple-negative breast cancer (TNBC) cell line MDA-MB-231 upon hyperoxic (95% O2) conditions. MAIN METHODS: MDA-MB-231 cells were stably transfected with Flag-tagged Sirt-3 or empty plasmid. Western blot and real-time PCR were used to monitor the expression of proteins or genes involved in mitochondrial biogenesis, metabolic regulation and antioxidant defense. Immunocytochemistry and confocal microscopy were used to confirm the cellular localization and abundance of proteins. Flow cytometry was used to analyze mitochondrial mass, potential and ROS production, and MTT test as a measure of metabolic activity. Mitotic index analysis, colony-forming unit assay, DNA damage and Annexin V-FITC analyses were used to assess the differences in the growth and apoptosis rate. KEY FINDINGS: Although Sirt3 seemed to improve mitochondrial properties by increasing mitochondrial mass and potential, metabolic activity (Warburg effect) and antioxidative defense (SOD2, Cat), it also increased mitochondrial ROS, induced DNA damage, timp-1 expression, formation of multinucleated cells and apoptosis, and finally markedly reduced the proliferation of MDA-MB-231 cells. All these effects were even more evident upon the hyperoxic treatment, thus pointing towards combined negative effect of Sirt3 and hyperoxia on MDA-MB-231 cells. SIGNIFICANCE: Both Sirt3 and hyperoxia, alone or in combination, have the potential to negatively affect the malignant properties of the MDA-MB-231 cells and should be further explored as a possible therapy for TNBC.

Electric Fields at Breast Cancer and Cancer Cell Collective Galvanotaxis.

Cancer growth interferes with local ionic environments, membrane potentials, and transepithelial potentials, resulting in small electrical changes in the tumor microenvironment. Electrical fields (EFs) have significant effects on cancer cell migration (galvanotaxis/electrotaxis), however, their role as a regulator of cancer progression and metastasis is poorly understood. Here, we employed unique probe systems to characterize the electrical properties of cancer cells and their migratory ability under an EF. Subcutaneous tumors were established from a triple-negative murine breast cancer cell line (4T1), electric currents and potentials of tumors were measured using vibrating probe and glass microelectrodes, respectively. Steady outward and inward currents could be detected at different positions on the tumor surface and magnitudes of the electric currents on the tumor surface strongly correlated with tumor weights. Potential measurements also showed the non-homogeneous intratumor electric potentials. Cancer cell migration was then surveyed in the presence of EFs in vitro. Parental 4T1 cells and metastatic sublines in isolation showed random migration in EFs of physiological strength, whereas cells in monolayer migrated collectively to the anode. Our data contribute to an improved understanding of breast cancer metastasis, providing new evidence in support of an electrical mechanism that promotes this phenomenon.

Effect of Bicalutamide on the proliferation and invasion of human triple negative breast cancer MDA-MB-231 cells.

Previous studies have shown androgen receptor (AR) is associated with the occurrence, development, recurrence, metastasis, and prognosis of triple negative breast cancer (TNBC). More and more experts have noticed that AR signaling pathway plays an important role in the occurrence and development of TNBC. The purpose of this study is to detect the inhibitory efficacy and mechanism of Bicalutamide on the proliferation and invasion of TNBC cells.MDA-MB-231 cells of human breast cancer cells were treated with 0, 25, 100 µmol/L of Bicalutamide, cell proliferation assay was performed to assess cell proliferation viability by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, Thiazolyl Blue Tetrazolium Bromide assay and cell invasion was evaluated by Transwell assay. Meanwhile, flow cytometric analysis and western blotting were performed to investigate the mechanism of Bicalutamide on the proliferation and invasion of MDA-MB-231 cells.Bicalutamide could efficiently inhibit the proliferation and invasion of MDA-MB-231 cells in a dose-dependent manner. In addition, Bicalutamide could significantly induce the cell cycle arrest at G0/G1 phase and decrease the protein expression of AR, cyclin D1, matrix metalloprotease-2 (MMP-2), and matrix metalloprotease-9 (MMP-9).The present study indicated the Bicalutamide inhibited the proliferation and invasion process of triple negative breast cancer cells by targeting AR signaling pathway and down-regulating MMP-2/-9 protein expression levels.