Promotes Breast Cancer Cell Invasion Research Articles

Exosomal circ-0100519 promotes breast cancer progression via inducing M2 macrophage polarisation by USP7/NRF2 axis.

Breast cancer (BC) is one of the most prevalent malignant tumours that threatens women health worldwide. It has been reported that circular RNAs (circRNAs) play an important role in regulating tumour progression and tumour microenvironment (TME) remodelling. Differentially expression characteristics and immune correlations of circRNAs in BC were verified using high-throughput sequencing and bioinformatic analysis. Exosomes were characterised by nanoparticle transmission electron microscopy and tracking analysis. The biological function of circ-0100519 in BC development was demonstrated both in vitro and in vivo. Western blotting, RNA pull-down, RNA immunoprecipitation, flow cytometry, and luciferase reporter were conducted to investigate the underlying mechanism. Circ-0100519 was significant abundant in BC tumour tissues and related to poor prognosis. It can be encapsulated into secreted exosomes, thereby promoting BC cell invasion and metastasis via inducing M2-like macrophages polarisation.Mechanistically, circ-0100519 acted as a scaffold to enhance the interaction between the deubiquitinating enzyme ubiquitin-specific protease 7 (USP7) and nuclear factor-like 2 (NRF2) in macrophages, inducing the USP7-mediated deubiquitination of NRF2. Additionally,HIF-1α could function as an upstream effector to enhance circ-0100519 transcription. Our study revealed that exosomal circ-0100519 is a potential biomarker for BC diagnosis and prognosis, and the HIF-1α inhibitor PX-478 may provide a therapeutic target for BC.

Crosstalk between breast cancer-derived microRNAs and brain microenvironmental cells in breast cancer brain metastasis.

Breast cancer is the most frequent malignancy in women, constituting 15.2% of all new cancers diagnosed in the United States. Distant breast cancer metastasis accounts for the majority of breast cancer-related deaths; brain metastasis is the third most common site for metastatic breast cancer but is associated with worst prognosis of approximately eight months of survival. Current treatment options for breast cancer brain metastasis (BCBM) are limited and ineffective. To help identify new and effective therapies for BCBM, it is important to investigate the mechanisms by which breast cancer cells metastasize to the brain and thrive in the brain microenvironment. To this end, studies have reported that primary breast tumor cells can prime brain microenvironmental cells, including, astrocytes and microglia, to promote the formation of BCBM through the release of extracellular vesicle-microRNAs (miRNAs). Breast tumor-derived miRNAs can also promote breast cancer cell invasion through the blood-brain barrier by disrupting the integrity of the brain microvascular endothelial cells. In this review, we summarize current literature on breast cancer-derived BCBM-promoting miRNAs, cover their roles in the complex steps of BCBM particularly their interactions with microenvironmental cells within the brain metastatic niche, and finally discuss their therapeutic applications in the management of BCBM.

Extracellular Hsp90 Binds to and Aligns Collagen-1 to Enhance Breast Cancer Cell Invasiveness.

Cancer cell-secreted eHsp90 binds and activates proteins in the tumor microenvironment crucial in cancer invasion. Therefore, targeting eHsp90 could inhibit invasion, preventing metastasis-the leading cause of cancer-related mortality. Previous eHsp90 studies have solely focused on its role in cancer invasion through the 2D basement membrane (BM), a form of extracellular matrix (ECM) that lines the epithelial compartment. However, its role in cancer invasion through the 3D Interstitial Matrix (IM), an ECM beyond the BM, remains unexplored. Using a Collagen-1 binding assay and second harmonic generation (SHG) imaging, we demonstrate that eHsp90 directly binds and aligns Collagen-1 fibers, the primary component of IM. Furthermore, we show that eHsp90 enhances Collagen-1 invasion of breast cancer cells in the Transwell assay. Using Hsp90 conformation mutants and inhibitors, we established that the Hsp90 dimer binds to Collagen-1 via its N-domain. We also demonstrated that while Collagen-1 binding and alignment are not influenced by Hsp90's ATPase activity attributed to the N-domain, its open conformation is crucial for increasing Collagen-1 alignment and promoting breast cancer cell invasion. These findings unveil a novel role for eHsp90 in invasion through the IM and offer valuable mechanistic insights into potential therapeutic approaches for inhibiting Hsp90 to suppress invasion and metastasis.

Unraveling the Role of Hepatic PGC1α in Breast Cancer Invasion: A New Target for Therapeutic Intervention?

Breast cancer (BC) is the most common cancer among women worldwide and the main cause of cancer deaths in women. Metabolic components are key risk factors for the development of non-alcoholic fatty liver disease (NAFLD), which may promote BC. Studies have reported that increasing PGC1α levels increases mitochondrial biogenesis, thereby increasing cell proliferation and metastasis. Moreover, the PGC1α/ERRα axis is a crucial regulator of cellular metabolism in various tissues, including BC. However, it remains unclear whether NAFLD is closely associated with the risk of BC. Therefore, the present study aimed to determine whether hepatic PGC1α promotes BC cell invasion via ERRα. Various assays, including ELISA, western blotting, and immunoprecipitation, have been employed to explore these mechanisms. According to the KM plot and TCGA data, elevated PGC1α expression was highly associated with a shorter overall survival time in patients with BC. High concentrations of palmitic acid (PA) promoted PGC1α expression, lipogenesis, and inflammatory processes in hepatocytes. Conditioned medium obtained from PA-treated hepatocytes significantly increased BC cell proliferation. Similarly, recombinant PGC1α in E0771 and MCF7 cells promoted cell proliferation, migration, and invasion in vitro. However, silencing PGC1α in both BC cell lines resulted in a decrease in this trend. As determined by immunoprecipitation assay, PCG1a interacted with ERRα, thereby facilitating the proliferation of BC cells. This outcome recognizes the importance of further investigations in exploring the full potential of hepatic PGC1α as a prognostic marker for BC development.

ITGB1BP1, a Novel Transcriptional Target of CD44-Downstream Signaling Promoting Cancer Cell Invasion.

Breast cancer (BC) is the most common malignancy worldwide and has a poor prognosis, because it begins in the breast and disseminates to lymph nodes and distant organs. While invading, BC cells acquire aggressive characteristics from the tumor microenvironment through several mechanisms. Thus, understanding the mechanisms underlying the process of BC cell invasion can pave the way towards the development of targeted therapeutics focused on metastasis. We have previously reported that the activation of CD44 receptor with its major ligand hyaluronan (HA) promotes BC metastasis to the liverin vivo. Next, a gene expression profiling microarray analysis was conducted to identify and validate CD44-downstream transcriptional targets mediating its pro-metastatic function from RNA samples collected from Tet CD44-inducedversuscontrol MCF7-B5 cells. We have already validated a number of novel CD44-target genes and published their underlying signaling pathways in promoting BC cell invasion. From the same microarray analysis, Integrin subunit beta 1 binding protein 1 (ITGB1BP1) was also identified as a potential CD44-target gene that was upregulated (2-fold) upon HA activation of CD44. This report will review the lines of evidence collected from the literature to support our hypothesis, and further discuss the possible mechanisms linking HA activation of CD44 to its novel potential transcriptional target ITGB1BP1.

Amino-Modified Magnetic Nanoparticles Used in Exploring the Mechanism of CCL18-Induced H19 Upregulation that Promotes Breast Cancer Cell Invasion by Regulating the EZH2-Mediated Repression of E-Cadherin Expression

The acceleration of Chemokine (C–C motif) ligand 18 (CCL18) and long noncoding RNA H19 expression is reportedly closely associated with breast cancer (BC) development and progression; however, the underlying mechanism and clinical value between CCL18 and H19 in BC remain unclear. Hence, this study aimed to examine the expression and function of CCL18 and H19 in BC tissues and cells by real-time polymerase chain reaction, immunohistochemistry, and other methods. We also detected the binding of EZH2 and other proteins to H19 through nanomagnetic bead immunoprecipitation and analyzed the roles of CCL18 and H19 in BC progression and their underlying mechanisms. Both CCL18 and H19 were upregulated in BC tissues and cell lines. High expression of CCL18 and EZH2 was closely associated with short survival in patients with BC. CCL18 or H19 silencing can prohibit BC cell invasion. Moreover, CCL18 accelerated the invasiveness of BC cells dose-dependently, and its expression was positively related to H19 expression in BC tissues. CCL18 enhanced H19 expression, while H19 knockdown partially ameliorated CCL18-induced BC cell invasiveness. Mechanistically, H19 can directly bind with EZH2 and mediate its accumulation at the promoter region of E-cadherin genes, consequently inhibiting E-cadherin expression. In conclusion, CCL18 promotes BC progression by enhancing H19 expression, and H19 overexpression suppresses E-cadherin expression via EZH2-mediated inhibition. Thus, this study describes a potential biomarker for the diagnosis, prognosis, and treatment of BC.

Heat treatment-induced autophagy promotes breast cancer cell invasion and metastasis via TGF-β2-mediated epithelial-mesenchymal transitions.

Insufficient thermal ablation can accelerate malignant behaviors and metastases in some solid tumors, and epithelial-mesenchymal transition (EMT) and autophagy are involved in tumor metastasis. It has been found that TGF-β2 which belongs to the family of transforming growth factors often associated with cancer cell invasiveness and EMT. However, whether the interactions between autophagy and TGF-β2 induce EMT in breast cancer (BC) cells following insufficient microwave ablation (MWA) remains unclear. BC cells were treated with sublethal heat treatment to simulate insufficient MWA, and the effects of heat treatment on the BC cell phenotypes were explored. CCK-8, colony formation, flow cytometry, Transwell, and wound healing assays were performed to evaluate the influence of sublethal heat treatment on the proliferation, apoptosis, invasion, and migration of BC cells. Western blotting, real-time quantitative PCR, immunofluorescence, and transmission electron microscopy were carried out to determine the changes in markers associated with autophagy and EMT following sublethal heat treatment. Results showed that heat treatment promoted the proliferation of surviving BC cells, which was accompanied by autophagy induction. Heat treatment-induced autophagy up-regulated TGF-β2/Smad2 signaling and promoted EMT phenotype, thereby enhancing BC cells' migration and invasion abilities. An increase or decrease of TGF-β2 expression resulted in the potentiation and suppression of autophagy, as well as the enhancement and abatement of EMT. Autophagy inhibitors facilitated apoptosis and repressed proliferation of BC cells in vitro, and thwarted BC cell tumor growth and pulmonary metastasis in vivo. Heat treatment-induced autophagy promoted invasion and metastasis via TGF-β2/Smad2-mediated EMTs. Suppressing autophagy may be a suitable strategy for overcoming the progression and metastasis of residual BC cells following insufficient MWA.

Doublecortin-like kinase 2 promotes breast cancer cell invasion and metastasis.

Doublecortin-like kinase 2 (DCLK2) is a microtubule-associated protein kinase that participates in neural development and maturation; however, whether it is involved in tumour progression remains unclear. DCLK2 overexpression and knockdown clones were established by lentivirus transfection. Western blot, PCR assays and bioinformatics analyses were conducted to observe the expression of DCLK2. CCK8, colony formation, scratch migration and Transwell assays were used to detect cell proliferation, migration and invasion, respectively. Tumour metastasis was evaluated in vivo using a tail vein metastasis model. Bioinformatics analyses were performed to analyse the expression correlation between DCLK2 and TCF4, or EMT markers in breast cancer. Our data indicate that DCLK2 is highly expressed in breast cancer cells and is associated with poor prognosis. Silencing DCLK2 does not affect the proliferation rate of tumour cells, but significantly suppresses migration and invasion as well as lung metastasis processes. Overexpression of DCLK2 can enhance the migratory and invasive abilities of normal breast epithelial cells. Moreover, TCF4/β-catenin inhibitor LF3 downregulates the expression of DCLK2 and inhibits the migration and invasion of breast cancer cells. Furthermore, we found that the downregulation of DCLK2 blocks the epithelial-mesenchymal transition (EMT) process. Our study indicates that DCLK2 plays an important role in EMT, cell invasion and metastasis, suggesting that DCLK2 is a potential target for the treatment of metastatic breast cancer.

Tenascin-C (TNC) Promotes Breast Cancer Cell Invasion and Proliferation: Functional Effects of TNC Knockdown in Highly Invasive Breast Cancer Cell Lines

Tenascin-C (TNC) Promotes Breast Cancer Cell Invasion and Proliferation: Functional Effects of TNC Knockdown in Highly Invasive Breast Cancer Cell Lines

Anti-PITPNM3 small molecular compounds reverse breast cancer metastasis by targeting PITPNM3.

e15005 Background: Recent studies highlight the fundamental roles of PITPNM3 in breast cancer metastasis. PITPNM3 is identified as the functional receptor of CCL18 and promotes breast cancer cell invasion and metastasis by binding with CCL18. Since anti-CCL18 neutralized antibodies shows medium binding affinity which restricts their clinical application, small molecular inhibitors targeting PITPNM3 are needed to be further investigated. Therefore, we identified several first in class small molecular inhibitors potentially targeting PITPNM3 and can inhibit breast cancer metastasis conducted by PITPNM3 activation. Methods: We performed computer-assisted drug design by constructing PITPNM3 homology model, characterizing potential binding pockets and docking preselected high diversity structured small molecule compounds into the static PITPNM3 model. Top 100 small molecules in silico scores were selected and screened through basic experiments. After screening, the anti-metastasis effects of selected compounds were tested through transwell migration and invasion assay. Immunofluorescence and qPCR were applied to confirm the expression of vimentin and CDH1. Western blot were used to clarify the inhibition effects of selected compounds on PITPNM3 signaling pathways. Results: By using homology remodeling, we successfully constructed the PITPNM3(680-920aa) protein model. The PITPNM3(680-920aa) domain is responsible for interacting with PYK2 and phosphorylating PYK2. The phosphorylation of PYK2 conducted by PITPNM3 signaling pathway will lead to metastasis and epithelial-mesenchymal transition (EMT) of breast cancer cells. We then characterized the potential binding pockets of this static model and a druggable site was founded. More than 50K molecules with high diversity were docked into this druggable site and scored through their docking performance. Finally, top 100 scored small molecules were selected. In addition, through 1 rounds of toxicity screening, 1 round of transwell migration assay screening and 1 round of transwell invasion assay screening, 4 small molecules with higher bioactivity is identified and 1 compound with the highest bioactivity as well as docking performance among 50K small molecules is chose. This compound can inhibit CCL18 treatment as well as tumor associated macrophage co-culture mediated migration and invasion. Besides, it can also inhibit the phophorylation of PYK2 and Src without inhibition the expression of PITPNM3. Conclusions: Our findings identify the first-in-class anti-PITPNM3 small molecule inhibitors. These compounds can inhibit PITPNM3 signaling pathway and reverse breast cancer metastasis.

L-plastin Ser5 phosphorylation is modulated by the PI3K/SGK pathway and promotes breast cancer cell invasiveness

BackgroundMetastasis is the predominant cause for cancer morbidity and mortality accounting for approximatively 90% of cancer deaths. The actin-bundling protein L-plastin has been proposed as a metastatic marker and phosphorylation on its residue Ser5 is known to increase its actin-bundling activity. We recently showed that activation of the ERK/MAPK signalling pathway leads to L-plastin Ser5 phosphorylation and that the downstream kinases RSK1 and RSK2 are able to directly phosphorylate Ser5. Here we investigate the involvement of the PI3K pathway in L-plastin Ser5 phosphorylation and the functional effect of this phosphorylation event in breast cancer cells.MethodsTo unravel the signal transduction network upstream of L-plastin Ser5 phosphorylation, we performed computational modelling based on immunoblot analysis data, followed by experimental validation through inhibition/overexpression studies and in vitro kinase assays. To assess the functional impact of L-plastin expression/Ser5 phosphorylation in breast cancer cells, we either silenced L-plastin in cell lines initially expressing endogenous L-plastin or neoexpressed L-plastin wild type and phosphovariants in cell lines devoid of endogenous L-plastin. The established cell lines were used for cell biology experiments and confocal microscopy analysis.ResultsOur modelling approach revealed that, in addition to the ERK/MAPK pathway and depending on the cellular context, the PI3K pathway contributes to L-plastin Ser5 phosphorylation through its downstream kinase SGK3. The results of the transwell invasion/migration assays showed that shRNA-mediated knockdown of L-plastin in BT-20 or HCC38 cells significantly reduced cell invasion, whereas stable expression of the phosphomimetic L-plastin Ser5Glu variant led to increased migration and invasion of BT-549 and MDA-MB-231 cells. Finally, confocal image analysis combined with zymography experiments and gelatin degradation assays provided evidence that L-plastin Ser5 phosphorylation promotes L-plastin recruitment to invadopodia, MMP-9 activity and concomitant extracellular matrix degradation.ConclusionAltogether, our results demonstrate that L-plastin Ser5 phosphorylation increases breast cancer cell invasiveness. Being a downstream molecule of both ERK/MAPK and PI3K/SGK pathways, L-plastin is proposed here as a potential target for therapeutic approaches that are aimed at blocking dysregulated signalling outcome of both pathways and, thus, at impairing cancer cell invasion and metastasis formation.9rn5EeEuriEpmsCBgdyXncVideo abstract

Novel role of BRCA1 interacting C-terminal helicase 1 (BRIP1) in breast tumour cell invasion.

Breast cancer (BC) is the most common malignancy and the leading cause of death in women worldwide. Only 5%‐10% of mutations in BRCA genes are associated with familial breast tumours in Eastern countries, suggesting the contribution of other genes. Using a microarray gene expression profiling study of BC, we have recently identified BRIP1 (fivefold up‐regulation) as a potential gene associated with BC progression in the Omani population. Although BRIP1 regulates DNA repair and cell proliferation, the precise role of BRIP1 in BC cell invasion/metastasis has not been explored yet; this prompted us to test the hypothesis that BRIP1 promotes BC cell proliferation and invasion. Using a combination of cellular and molecular approaches, our results revealed differential overexpression of BRIP1 in different BC cell lines. Functional assays validated further the physiological relevance of BRIP1 in tumour malignancy, and siRNA‐mediated BRIP1 knockdown significantly reduced BC cell motility by targeting key motility‐associated genes. Moreover, down‐regulation of BRIP1 expression significantly attenuated cell proliferation via cell cycle arrest. Our study is the first to show the novel function of BRIP1 in promoting BC cell invasion by regulating expression of various downstream target genes. Furthermore, these findings provide us with a unique opportunity to identify BRIP1‐induced pro‐invasive genes that could serve as biomarkers and/or targets to guide the design of appropriate BC targeted therapies.

Extracellular ATP promotes breast cancer invasion and chemoresistance via SOX9 signaling.

Our previous research demonstrated that extracellular adenosine 5'-triphosphate (ATP) could promote breast cancer cell invasion. However, the impact of extracellular ATP on chemoresistance and the mechanisms behind ATP pro-invasion and pro-chemoresistance remain unclear. Here we aimed to determine the molecules or signaling pathways involved. cDNA microarray was performed to identify the differentially expressed genes before and after ATP treatment. As a result, Sex-determining region Y-box 9 (SOX9) was up-regulated after ATP treatment in breast cancer cells. In vitro invasion and migration assays demonstrated that knocking down SOX9 attenuated ATP-driven invasive capability. Mass spectrometry and co-IP revealed that SOX9 interacted with Janus kinase 1 (JAK1). Afterward, IL-6-JAK1-STAT3 signaling was demonstrated to promote SOX9 expression and invasion following ATP treatment. Notably, ATP-IL-6-SOX9 signaling was shown to stimulate chemoresistance in breast cancer cells. ChIP assays identified some potential SOX9 target genes, among which carcinoembryonic antigen-related cell adhesion molecule 5/6 (CEACAM5/6) was demonstrated to mediate ATP pro-invasive function, while ATP-binding cassette subfamily B member 1 (ABCB1) and ATP-binding cassette subfamily G member 2 (ABCG2) mediated ATP-driven chemoresistance. In addition, SOX9-knockdown and apyrase (an ATP hydrolase)-treated MDA-MB-231 cells illustrated decreased tumor growth and enhanced drug sensitivity in nude mice. In vitro spheroid formation assays also proved the significance of ATP-SOX9 in mediating chemoresistance. Moreover, molecules involved in ATP-SOX9 signaling were up-regulated in human breast carcinoma specimens and were associated with poor prognosis. Altogether, SOX9 signaling is vital in ATP-driven invasion and chemoresistance, which may serve as a potential target for breast cancer therapies.

Increased SIX-1 expression promotes breast cancer metastasis by regulating lncATB-miR-200s-ZEB1 axis.

Patients with advanced breast cancer (BC) showed a higher incidence of regional and distant metastases. Sine oculis homeobox homolog 1 (SIX‐1) has been confirmed to be a key tumorigenic and metastatic regulator in BC progression. Yet, molecular mechanisms behind SIX‐1‐induced BC metastases remain largely unknown. Here we found that SIX‐1 was frequently up‐regulated in BC and correlated with poor outcomes when tested in human BC tissue microarray. Then, we manipulated the expression of SIX‐1 by via shRNA‐mediated knockdown and lentivirus‐mediated overexpression. Transwell assay in vitro and lung metastases model of nude mice in vivo showed that SIX‐1 promoted BC cell invasion and migration in vitro, and facilitated metastases in vivo. Mechanistically, SIX‐1 could promote the transcription of lncATB, which exerts critical pro‐metastatic role in BC by directly binding to the miR‐200 family, especially for miR‐200c, to induce EMT and promote metastases. In conclusion, SIX‐1 exerts its pro‐metastatic role in BC through lncATB/miR‐200s axis of EMT signalling pathway and could act as an important diagnostic marker as well as a significant therapeutic target for clinically advanced BC.

Silencing of Growth Differentiation Factor-15 Promotes Breast Cancer Cell Invasion by Down-regulating Focal Adhesion Genes.

As metastasis accounts for most breast cancer (BC)-related deaths, identifying key players becomes research priority. Growth differentiation factor-15 (GDF15), a member of the transforming growth factor-β superfamily, is affected by the actin cytoskeleton and has been associated with cancer. However, its exact role in BC cell invasiveness is vague. GDF15 short-hairpin (shRNA)-mediated silencing was used to inhibit GDF15 expression in MCF-7 and MDA-MB-231 BC cells and gene expression of relevant focal adhesion (FA) genes, cell migration, invasion and tumor spheroid invasion were subsequently analyzed. GDF15 silencing promoted cell migration, cell invasion as well as tumor spheroid invasion and up-regulated urokinase plasminogen activator (uPA) and FA genes, integrin-linked kinase (ILK), LIM zinc finger domain containing 1 (LIMS1), α-parvin (PARVA), and RAS suppressor-1 (RSU1). Computational analysis of Cancer Genome Atlas BC dataset however, revealed no significant correlation between GDF15 expression and metastasis pointing towards a more complex molecular interplay between GDF15, actin cytoskeleton and FA-related genes which ultimately affects their expression pattern, in vivo. GDF15 suppresses BC cell invasion in vitro through down-regulation of FA genes but its role in BC is more complicated in vivo and warrants further investigation.

Interleukin-22 Mediates the Chemotactic Migration of Breast Cancer Cells and Macrophage Infiltration of the Bone Microenvironment by Potentiating S1P/SIPR Signaling.

The interleukin-22 (IL-22) signaling pathway is well known to be involved in the progression of various cancer types but its role in bone metastatic breast cancer remains unclear. We demonstrate using human GEO profiling that bone metastatic breast cancer displays elevated interleukin-22 receptor 1 (IL-22R1) and sphingosine-1-phosphate receptor 1 (S1PR1) expression. Importantly, IL-22 stimuli promoted the expression of IL-22R1 and S1PR1 in aggressive MDA-MB-231 breast cancer cells. IL-22 treatment also increased sphingosine-1-phosphate production in mesenchymal stem cells (MSCs) and induced the sphingosine-1-phosphate (S1P)-mediated chemotactic migration of MDA-MB-231 cells. This effect was inhibited by an S1P antagonist. In addition to the S1PR1 axis, IL-22 stimulated the expression of matrix metalloproteinase-9 (MMP-9), thereby promoting breast cancer cell invasion. Moreover, IL-22 induced IL22R1 and S1PR1 expression in macrophages, myeloid cell, and MCP1 expression in MSCs to facilitate macrophage infiltration. Immunohistochemistry indicated that IL-22R1 and S1PR1 are overexpressed in invasive malignant breast cancers and that this correlates with the MMP-9 levels. Collectively, our present results indicate a potential role of IL-22 in driving the metastasis of breast cancers into the bone microenvironment through the IL22R1-S1PR1 axis.

PA28α/β Promote Breast Cancer Cell Invasion and Metastasis via Down-Regulation of CDK15.

PA28α/β activated immunoproteasome frequently participates in MHC class I antigen processing, however, whether it is involved in breast tumor progression remains largely unclear. Here, our evidences show that PA28α/β proteins are responsible for breast cancer cell migration, invasion, and metastasis. Knockdown of immunoproteasome core subunit β5i also robustly suppresses the tumor cell migration and invasion. Interestingly, silencing of PA28α/β and β5i up-regulates the protein expression of cyclin-dependent kinase 15 (CDK15). Our data further indicate that the loss of CDK15 is important for breast tumor cell invasion and metastasis. Taken together, this study implicates that targeting of PA28α/β represents a potential way for treatment of metastatic breast cancer.

Circadian protein BMAL1 promotes breast cancer cell invasion and metastasis by up-regulating matrix metalloproteinase9 expression

BackgroundMetastasis is an important factor in the poor prognosis of breast cancer. As an important core clock protein, brain and muscle arnt-like 1 (BMAL1) is closely related to tumorigenesis. However, the molecular mechanisms that mediate the role of BMAL1 in invasion and metastasis remain largely unknown. In this study, we investigated the BMAL1 may take a crucial effect in the progression of breast cancer cells.MethodsBMAL1 and MMP9 expression was measured in breast cell lines. Transwell and scratch wound-healing assays were used to detect the movement of cells and MTT assays and clonal formation assays were used to assess cells’ proliferation. The effects of BMAL1 on the MMP9/NF-κB pathway were examined by western blotting, co-immunoprecipitation and mammalian two-hybrid.ResultsIn our study, it showed that cell migration and invasion were significantly enhanced when overexpressed BMAL1. Functionally, overexpression BMAL1 significantly increased the mRNA and protein level of matrix metalloproteinase9 (MMP9) and improved the activity of MMP9. Moreover, BMAL1 activated the NF-κB signaling pathway by increasing the phosphorylation of IκB and promoted human MMP9 promoter activity by interacting with NF-kB p65, leading to increased expression of MMP9. When overexpressed BMAL1, CBP (CREB binding protein) was recruited to enhance the activity of p65 and further activate the NF-κB signaling pathway to regulate the expression of its downstream target genes, including MMP9, TNFα, uPA and IL8, and then promote the invasion and metastasis of breast cancer cells.ConclusionsThis study confirmed a new mechanism by which BMAL1 up-regulated MMP9 expression to increase breast cancer metastasis, to provide research support for the prevention and treatment of breast cancer.

NRF3 suppresses breast cancer cell metastasis and cell proliferation and is a favorable predictor of survival in breast cancer.

Background: Cancer metastasis is the leading cause of cancer-related death in breast cancer. However, our understanding of its mechanisms is still limited. At this study, the biological roles and clinical significance of NRF3 (NFE2L3, nuclear factor, Erythroid 2 Like 3) in breast cancer are evaluated for the first time.Methods: NRF3 expression in breast cancer cell lines and clinical specimens was determined by western blot and immunohistochemistry, respectively. Cell proliferation, cell cycle distribution, cell migration, and invasion were detected by MTT, colony formation, flow cytometry, and transwell assays, respectively. All other proteins were measured by western blot. The clinical significance of NRF3 was analyzed using the data from tissue microarray.Results: We found that NRF3 expression was obviously suppressed in breast cancer tissues, and negatively associated with the Lymph node metastasis status and tumor stages. Our data also indicated NRF3 expression was much higher in MCF-7 cells than that in MDA-MB-231 and SKBR3 cells which were more malignant. Silence of NRF3 in MCF-7 cells could significantly promote cell proliferation by reducing the cell number in the G0/G1 phase. Exogenous expression of NRF3 in SKBR3 and MDA-MB-231 cells effectively inhibited both cell growth and metastasis with epithelial–mesenchymal transition and MMPs expression suppressed. NRF3 overexpression also impaired the ID3 expression by inactivating the AKT signaling pathway. Exogenous expression of ID3 could not only effectively promote breast cancer cell invasion by inhibiting E-cadherin expression and upregulating MMP-2 expression, but also attenuated the inhibitory function of NRF3 on the breast cancer cell invasion.Conclusion: Our findings suggested that NRF3 inhibited breast cancer cell proliferation and metastasis via inhibiting AKT/ID3 axis at least partially, and potentially to be a valuable clinic marker in breast cancer prognosis.

Molecular Actions of Thyroid Hormone on Breast Cancer Cell Migration and Invasion via Cortactin/N-WASP

The thyroid hormone triiodothyronine (T3) plays a fundamental role in growth regulation, differentiation, metabolism and cellular movement. These processes are particularly important considering that deregulation of T3 levels could promote abnormal responsiveness of mammary epithelial cells, which may lead to the development and progression of breast cancer (BC). Once cells migrate and invade different tissues, BC metastasis is the main cause of cancer-related death because it is particularly difficult to revert this multistep process. Cell migration integrates several steps that induce changes in cell structure and morphology to promote BC cell invasion. These sequential steps include actin cytoskeleton remodeling, focal adhesion complex formation and, finally, the turnover of branched actin filament networks. In this article, we demonstrate that T3 has the ability to modify the Epithelial-Mesenchymal Transition process. In addition, we show that T3 induces actin cytoskeleton reorganization, triggers focal adhesion formation and, as a consequence, promotes actin nucleation via non-genomic pathway. These events are specifically modulated by T3 via integrin αvβ3 to FAK/paxillin/cortactin/N-WASP/Arp2/3 complex signaling pathway, increasing cell adhesion, migration and invasion of T-47D BC cells. We suggest that T3 influences the progression of tumor metastasis by controlling signaling pathways that converge in cell motility. This knowledge is crucial for the development of novel therapeutic strategies for BC treatment.