Promotes Breast Cancer Cell Migration Research Articles

Abstract B037: Expression of MRTFA facilitates an immunosuppressive tumor microenvironment via upregulation of VSIR

Abstract Breast cancer, the second highest cause of cancer-related deaths in women, accounts for 31% of female cancer diagnoses. African American women have lower survival rates than White American women, influenced by both biological factors (age, family history, genetic factors, tumor biology) and social determinants (socio-economic status, insurance status, health care access). However, precise biological determinants remain unclear. The primary reason for breast cancer mortality is metastasis to organs like the lung, liver, and brain, with transcription factors playing a key role in this process. Myocardin related transcription factor A/B (MRTFA/B) are co-activators of serum-response factor (SRF), and the MRTF-SRF complex promotes breast cancer cell migration, invasion, and metastasis by regulating genes involved in actin cytoskeleton remodeling. MRTFA also supports tumor growth by modulating cancer-associated fibroblasts (CAFs) and remodeling the extracellular matrix (ECM) in the tumor microenvironment. While the pro-metastatic role of MRTFA/B is established in vitro and in mice, their impact on human cancer progression and metastasis requires further investigation. Therefore, understanding MRTFA's role in breast cancer metastasis is crucial for improving patient outcomes, making it essential to investigate MRTFA/B expression patterns in both tumor cells and the tumor microenvironment (TME). To explore the clinical, demographic, tumor-intrinsic, and tumor microenvironmental patterns of MRTFA/B’s expression and activation, we utilized multiplex imaging methods on multiple racially diverse tissue microarrays (TMA) and bioinformatics analyses of The Cancer Genome Atlas (TCGA), Molecular Taxonomy of Breast Cancer International Consortium (METABRIC), and available single-cell RNA sequencing datasets. Strikingly, MRTFA expression levels were higher in African American patients than in White American patients. Next, we investigated MRTFA expression patterns in the TME by using single-cell sequencing databases and found more abundant MRTFA expression in dendritic cells (DCs) within the TME compared to any other cell subtype. Moreover, our multiplex-imaging of tumor microarray (TMA) samples showed prominent MRTFA expression in HLA-DRA+CD45+ cells, indicative of antigen-presenting cells (APC). Notably, public single-cell RNA sequencing data indicated that breast cancer DCs strongly express the V-set immunoregulatory receptor (VSIR), an immune checkpoint protein, implying the immunosuppressive nature of the TME and we found that this increased VSIR expression is mediated by the MRTF-SRF complex. These findings suggest that DCs expressing MRTFA in breast cancer microenvironment contribute to creating the immunosuppressive TME via upregulation of VSIR expression, resulting in racial breast cancer disparities. Citation Format: Kihak Lee, Stephanie M. Wilk, Alexa M. Gajda, Mohamed Haloul, Virgilia Macias, Elizabeth L. Wiley, Zhengjia Chen, Xinyi Liu, Xiaowei Wang, Maria Sverdlov, Kent F. Hoskins, Ekrem Emrah Er. Expression of MRTFA facilitates an immunosuppressive tumor microenvironment via upregulation of VSIR [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B037.

DDX5-Targeting Fragile X Mental Retardation Protein Regulates the Wnt/β-catenin Signaling Pathway to Promote Epithelial Mesenchymal Transition in Breast Cancer

To investigate the role of fragile X mental retardation protein (FMRP) in promoting cell migration and epithelial-mesenchymal transition (EMT) in breast cancer (BC) and the potential mechanisms involved. The mRNA and protein expressions of FMRP in MCF-10A, a normal human breast epithelial cell line, and four breast cancer cell lines, including MCF-7, BT474, MDA-MB-231, and HCC1937, were analyzed by RT-PCR and Western blot. The expression of FMRP in BC tissues was measured by immunohistochemistry (IHC). FMRP expression in BC and its relationship with clinical prognosis were analyzed using GEO database. Lentiviral infection and siRNA interference were used to construct FMRP overexpression and interference vectors, respectively, and the human breast cancer cell line MCF-7 was subsequently transfected. A Control group, an interference empty vector group (the NC group), a knockdown vector group (the siFMRP group), an overexpression empty vector group (the Lv-NC group), and an overexpression vector group (the Lv-FMRP group) were set up. The migration and invasion abilities of the cells were assessed by scratch assay and Transwell assay. The expression of EMT markers, including E-cadherin, an epithelial marker, N-cadherin, an mesenchymal markers, vimentin, zinc finger E-box binding homeobox 1 (ZEB1), and snail family zinc finger 2 (Slug), in the cells of each group was determined by Western blot. The interaction between FMRP and DEAD-box RNA helicase-5 (DDX5) protein was analyzed by immunocoprecipitation combined with mass spectrometry (IP-MS). The regulatory effect of FMRP on DDX5 protein expression was assessed using the protein synthesis inhibitor cycloheximide (CHX) and proteasome inhibitor MG132. In addition, transfection with siDDX5 vector was conducted to observe whether DDX5 could reverse the effects of FMRP overexpression on cell migration and EMT. The localization and expression of β-catenin were determined by immunofluorescence staining, and the expression of core markers of Wnt/β-catenin signaling pathway was examined by Western blot. FMRP was highly expressed in BC tissues and cells (P<0.05), and overall survival (OS) and recurrence-free survival (RFS) of the FMRP high expression group were significantly lower than those of the FMRP low expression group (P<0.05). The migration ability of MCF-7 cells was weakened after FMRP knockdown, while overexpression of FMRP promoted cell migration (P<0.05). After FMRP knockdown, the expression of E-cadherin was increased, while the expression levels of N-cadherin, vimentin, ZEB1, and Slug were decreased, which inhibited the occurrence of EMT. In contrast, the overexpression of FMRP promoted the EMT process (P<0.05). FMRP interacted with DDX5 protein and promoted DDX5 protein stability by blocking the ubiquitin-proteasome pathway. DDX5 knockdown reversed the effect of FMRP overexpression to promote cell migration and EMT (P<0.05), effectively inhibited β-catenin nuclear translocation, and decreased β-catenin nuclear distribution. Furthermore, it was found that the expression of p-β-catenin, GSK3β and Axin2 protein was increased and the expression of C-myc protein was decreased after DDX5 downregulation (P<0.05). On the other hand, the expression of these proteins was reversed by combined FMRP overexpression (P<0.05). FMRP targets DDX5 and promotes BC cell migration and EMT via the activation of the Wnt/β-catenin signaling pathway.

USP7 deubiquitinates epigenetic reader ZMYND8 to promote breast cancer cell migration and invasion

The ubiquitin-proteasome system (UPS), which involves E3 ligases and deubiquitinases (DUBs), is critical for protein homeostasis. The epigenetic reader ZMYND8 (zinc finger MYND-type containing 8) has emerged as an oncoprotein, and its protein levels are elevated in various types of cancer, including breast cancer. However, the mechanism by which ZMYND8 protein levels are increased in cancer remains elusive. Although ZMYND8 has been reported to be regulated by the E3 ligase FBXW7, it is still unknown whether ZMYND8 could be modulated by DUBs. Here, we identified USP7 (ubiquitin carboxyl-terminal hydrolase 7) as a bona fide DUB for ZMYND8. Mechanically, USP7 directly binds to the PBP (PHD-BRD-PWWP) domain of ZMYND8 via its TRAF (tumor necrosis factor receptor-associated factor) domain and UBL (ubiquitin-like) domain and removes F-box and WD repeat domain containing 7 (FBXW7)-catalyzed poly-ubiquitin chains on lysine residue 1034 (K1034) within ZMYND8, thereby stabilizing ZMYND8 and stimulating the transcription of ZMYND8 target genes ZEB1 (zinc finger E-box binding homeobox 1) and VEGFA (Vascular Endothelial Growth Factor A). Consequently, USP7 enhances the capacity of breast cancer cells for migration and invasion through antagonizing FBXW7-mediated ZMYND8 degradation. Importantly, the protein levels of USP7 positively correlates with those of ZMYND8 in breast cancer tissues. These findings delineate an important layer of migration and invasion regulation by the USP7-ZMYND8 axis in breast cancer cells.

PTX promotes breast cancer migration and invasion by recruiting ATF4 to upregulate FGF19

BackgroundWidely-spread among women, breast cancer is a malignancy with fatalities, and chemotherapy is a vital treatment option for it. Recent studies have underscored the potential of chemotherapeutic agents such as paclitaxel, adriamycin, cyclophosphamide, and gemcitabine, among others, in facilitating tumor metastasis, with paclitaxel being extensively researched in this context. The molecular mechanism of these genes and their potential relevance to breast cancer is noteworthy. MethodClinical tissue specimens were used to analyze the expression and clinical significance of FGF19 or P-FGFR4 in patients with breast cancer before and after chemotherapy. qRT-PCR, ELISA, immunofluorescence and Western blotting were used to detect the expression level of FGF19 in breast cancer cells. The biological impacts of paclitaxel, FGF19, and ATF4 on breast cancer cells were assessed through CCK8, Transwell, and Western blot assays. The expression of ATF4 in breast cancer cells was determined through database analysis, Western blot analysis, qRT-PCR, and immunofluorescence. The direct interaction between FGF19 and ATF4 was confirmed by a luciferase assay, and Western blotting was used to assess the levels of key proteins in the stress response pathway. To confirm the effects of PTX and FGF19 in vivo, we established a lung metastasis model in nude mice. ResultsFGF19 expression was increased in breast cancer patients after chemotherapy. Paclitaxel can boost the migration and invasion of breast cancer cells, accompanied by an increase in FGF19 expression. ATF4 might be involved in facilitating the enhancing effect of FGF19 on breast cancer cell migration. Finally, stimulation during paclitaxel treatment could trigger a stress response, influencing the expression of FGF19 and the migration of breast cancer cells. ConclusionThese data suggest that paclitaxel regulates FGF19 expression through ATF4 and thus promotes breast cancer cell migration and invasion.

AGEs induce MMP-9 promoter demethylation through the GADD45α-mediated BER pathway to promote breast cancer metastasis in patients with diabetes.

Scientific evidence has linked diabetes to a higher incidence and increased aggressiveness of breast cancer; however, mechanistic studies of the numerous regulators involved in this process are insufficiently thorough. Advanced glycation end products (AGEs) play an important role in the chronic complications of diabetes, but the mechanisms of AGEs in breast cancer are largely unexplored. In this study, we first demonstrate that high AGE levels in breast cancer tissues are associated with the diabetic state and poor patient outcomes. Furthermore, AGEs interact with the receptor for AGEs (RAGE) to promote breast cancer cell migration and invasion. Mechanistically, based on RNA sequencing (RNA-seq) analysis, we reveal that growth arrest and DNA damage gene 45α (GADD45α) is a vital protein upregulated by AGEs through a P53-dependent pathway. Next, GADD45α recruits thymine DNA glycosylase for base excision repair to form the demethylation complex at the promoter region of MMP-9 and enhance MMP-9 transactivation through DNA demethylation. Overall, our results indicate a critical regulatory role of AGEs in patients with breast cancer and diabetes and reveal a novel mechanism of epigenetic modification in promoting breast cancer metastasis.

ING1 inhibits Twist1 expression to block EMT and is antagonized by the HDAC inhibitor vorinostat

ING1 is a chromatin targeting subunit of the Sin3a histone deacetylase (HDAC) complex that alters chromatin structure to subsequently regulate gene expression. We find that ING1 knockdown increases expression of Twist1, Zeb 1&2, Snai1, Bmi1 and TSHZ1 drivers of EMT, promoting EMT and cell motility. ING1 expression had the opposite effect, promoting epithelial cell morphology and inhibiting basal and TGF-β-induced motility in 3D organoid cultures. ING1 binds the Twist1 promoter and Twist1 was largely responsible for the ability of ING1 to reduce cell migration. Consistent with ING1 inhibiting Twist1 expression in vivo, an inverse relationship between ING1 and Twist1 levels was seen in breast cancer samples from The Cancer Genome Atlas (TCGA). The HDAC inhibitor vorinostat is approved for treatment of multiple myeloma and cutaneous T cell lymphoma and is in clinical trials for solid tumours as adjuvant therapy. One molecular target of vorinostat is INhibitor of Growth 2 (ING2), that together with ING1 serve as targeting subunits of the Sin3a HDAC complex. Treatment with sublethal (LD25-LD50) levels of vorinostat promoted breast cancer cell migration several-fold, which increased further upon ING1 knockout. These observations indicate that correct targeting of the Sin3a HDAC complex, and HDAC activity in general decreases luminal and basal breast cancer cell motility, suggesting that use of HDAC inhibitors as adjuvant therapies in breast cancers that are prone to metastasize may not be optimal and requires further investigation.

GATA zinc finger protein p66β promotes breast cancer cell migration by acting as a co-activator of Snail

The transcriptional repressor Snail induces EMT during embryonic development and tumor metastasis. Growing evidence indicates that Snail functions as a trans-activator to induce gene expression; however, the underlying mechanism remains elusive. Here, we report that Snail cooperates with GATA zinc finger protein p66β to transactivate genes in breast cancer cells. Biologically, depletion of p66β reduces cell migration and lung metastasis in BALB/c mice. Mechanistically, Snail interacts with p66β and cooperatively induces gene transcription. Notably, a group of genes induced by Snail harbor conserved G-rich cis-elements (5′-GGGAGG-3′, designated as G-box) in their proximal promoter regions. Snail directly binds to G-box via its zinc fingers and transactivates the G-box-containing promoters. p66β enhances Snail binding affinity to G-box, whereas depletion of p66β results in a decreased binding affinity of Snail to the endogenous promoters and concomitantly reduces the transcription of Snail-induced genes. Taken together, these data demonstrated that p66β is critical for Snail-mediated cell migration by acting as a co-activator of Snail to induce genes containing G-box elements in the promoters.

Pleckstrin-2-promoted PPM1B degradation plays an important role in transforming growth factor-β-induced breast cancer cell invasion and metastasis.

Transforming growth factor-β (TGF-β) is known to promote breast cancer cell migration, invasion, and dissemination; however, the underlying molecular mechanisms are not yet well characterized. Here, we report that TGF-β induces pleckstrin-2 (PLEK2) expression by Smad3 and signal transducer and activator of transcription 3 (STAT3) activating PLEK2 promoter activity. Higher PLEK2 expression is associated with poor prognosis in breast cancer patients. Overexpression and knockout experiments in MDA-MB-231 and MCF-7 breast cancer cells revealed that PLEK2 promotes cell migration, invasion, and dissemination in 2D and 3D cell culture. Moreover, PLEK2 promotes metastasis of breast cancer cells in vivo. Pleckstrin-2 localizes to the cell membrane and cell protrusions following TGF-β treatment. Furthermore, inhibition of PI3K phosphorylation abolishes TGF-β- and PLEK2-induced cell invasion. The carboxyl-terminal PH domain of PLEK2 is critical for TGF-β- and PLEK2-induced Akt activation and plays an important role in cell invasion. Pleckstrin-2 interacts with PPM1B and promotes its ubiquitin-dependent degradation. The PLEK2-PPM1B axis utilizes nuclear factor-κB signaling to promote cell migration and invasion. Our data implicate the TGF-β-STAT3/Smad3-PLEK2-PPM1B signaling cascade in TGF-β-induced breast cancer cell migration and invasion. These findings suggest that PLEK2/PPM1B could represent novel targets for the intervention of breast cancer metastasis.

Abstract P5-13-06: Overexpression of somatic mutation in NSDHL promotes breast cancer cell migration and tumor growth

Abstract Background: We had identified somatic mutations of the NAD(P) Dependent Steroid Dehydrogenase-Like (NSDHL) gene from breast tumors of patients with distant metastasis using whole-exome sequencing. This study aimed to investigate the function of NSDHL mutants in breast cancer. Methods: ER-positive and tamoxifen-resistant human breast cancer cell line (ZR75-1) and mouse macrophage cell line (RAW264,7) were used. GFP-tagged NSDHL mutants were generated by subcloning the mutant NDHL into a lentiviral vector yielding an in-frame fusion of 3′ to GFP. ZR75-1 cells expressing the GFP-tagged NSDHL mutants were selected by puromycin with subsequent FACS analysis. The following experiments were performed: western blot, immunofluorescence staining, qRT-PCR, CellTiter-Glo assay, cell cycle assay, transwell migration assay, wound healing assay, tumor spheroid formation assay, and total cellular cholesterol measurement. An orthotopic breast tumor mouse model by injection of ZR75.1 cells into mammary gland fat pad was used in vivo. Results: Four novel NSDHL somatic mutations were discovered in the breast tumor tissues of patients. While total cholesterol levels in NSDHL mutant-transduced cells did not significantly increase, they were notably higher in wild-type NSDHL-transduced cells than in parent ZR75-1 cells. When compared to the parent and wild-type NSDHL-transduced cells, there was a minor increase in growth rate and a large increase in migratory capacities in NSDHL mutant-transduced cells (P&amp;lt; 0.05). The size of tumor spheroids is significantly larger in NSDHL mutant-transduced cells than in wild-type NSDHL-transduced cells. Both EGFR expression and epithelial to mesenchymal transition (EMT) markers were higher in NSDHL mutant-transduced cells than in parent and wild-type NSDHL-transduced cells. The NSDHL mutant-transduced cells’ conditioned media promoted the migratory ability and M2 polarization of RAW264.7 cells. In an orthotopic xenograft mouse model, NSDHL mutant-transduced cells were shown to promote tumor growth better than parent and wild-type NSDHL-transduced cells, suggesting that somatic mutation of the NSDHL contributes to the malignant progression of breast cancer cells. Conclusion: The present data indicate that breast cancer cells harboring somatic mutants of the NSDHL gene seem to display more aggressive behavior by gaining biological worse phenotype both in vitro and in vivo. More investigation is required into the mechanisms behind the function and accumulation of mutant NSDHL proteins to speed the development of therapies for patients with breast cancer harboring mutant NSDHL. Citation Format: Moonjou Baek, Hoe Suk Kim, So-Hyun Yoon, Seungyeon Ryu, Sangeun Lee, Kyoungsook Park, Han-Byoel Lee, Wonshik Han. Overexpression of somatic mutation in NSDHL promotes breast cancer cell migration and tumor growth [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-13-06.

HBXIP blocks myosin-IIA assembly by phosphorylating and interacting with NMHC-IIA in breast cancer metastasis.

Tumor metastasis depends on the dynamic balance of the actomyosin cytoskeleton. As a key component of actomyosin filaments, non-muscle myosin-IIA disassembly contributes to tumor cell spreading and migration. However, its regulatory mechanism in tumor migration and invasion is poorly understood. Here, we found that oncoprotein hepatitis B X-interacting protein (HBXIP) blocked the myosin-IIA assemble state promoting breast cancer cell migration. Mechanistically, mass spectrometry analysis, co-immunoprecipitation assay and GST-pull down assay proved that HBXIP directly interacted with the assembly-competent domain (ACD) of non-muscle heavy chain myosin-IIA (NMHC-IIA). The interaction was enhanced by NMHC-IIA S1916 phosphorylation via HBXIP-recruited protein kinase PKCβII. Moreover, HBXIP induced the transcription of PRKCB, encoding PKCβII, by coactivating Sp1, and triggered PKCβII kinase activity. Interestingly, RNA sequencing and mouse metastasis model indicated that the anti-hyperlipidemic drug bezafibrate (BZF) suppressed breast cancer metastasis via inhibiting PKCβII-mediated NMHC-IIA phosphorylation invitro and invivo. We reveal a novel mechanism by which HBXIP promotes myosin-IIA disassembly via interacting and phosphorylating NMHC-IIA, and BZF can serve as an effective anti-metastatic drug in breast cancer.

MiRNA-1260b Promotes Breast Cancer Cell Migration and Invasion by Downregulating CCDC134.

Breast cancer (BRCA) is the most common type of cancer among women worldwide. MiR-1260b has been widely demonstrated to participate in multiple crucial biological functions of cancer tumorigenesis, but its functional effect and mechanism in human breast cancer have not been fully understood. qRT-PCR was used to detect miR-1260b expression in 29 pairs of breast cancer tissues and normal adjacent tissues. Besides, the expression level of miR-1260b in BRCA cells was also further validated by qRT-PCR. miR-1260b played its role in the prognostic process by using Kaplan-Meier curves. In addition, miR-1260b knockdown and target gene CCDC134 overexpression model was constructed in cell line MDA-MB-231. Transwell migration and invasion assay was performed to analyze the effect of miR-1260b and CCDC134 on the biological function of BRCA cells. TargetScan and miRNAWalk were used to find possible target mRNAs. The relationship between CCDC134 and immune cell surface markers was analyzed using TIMER and database and the XIANTAO platform. GSEA analysis was used to identify possible CCDC134-associated molecular mechanisms and pathways. In the present study, miR-1260b expression was significantly upregulated in human breast cancer tissue and a panel of human breast cancer cell lines, while the secretory protein coiled-coil domain containing 134 (CCDC134) exhibited lower mRNA expression. High expression of miR-1260b was associated with poor overall survival among the patients by KM plot. Knockdown of miR-1260b significantly suppressed breast cancer cell migration and invasion and yielded the opposite result. In addition, overexpression of CCDC134 could inhibit breast cancer migration and invasion, and knockdown yielded the opposite result. There were significant positive correlations of CCDC134 with CD25 (IL2RA), CD80 and CD86. GSEA showed that miR-1260b could function through the MAPK pathway by downregulating CCDC134. Collectively, these results suggested that miR-1260b might be an oncogene of breast cancer and might promote the migration and invasion of BRCA cells by down-regulating its target gene CCDC134 and activating MAPK signaling pathway as well as inhibiting immune function and causing immune escape in human breast cancer.

CBX3 promotes breast cancer progression and high level of CBX3 predicts poor prognosis in patients.

Breast cancer is one of the leading cancer deaths around the world. Targeted drugs have greatly increased the survival rate of breast cancer patients in recent years. But in some patients, the current regimen is still ineffective. Therefore, more therapeutic targets for treating breast cancer are demanding. The core heterochromatin-related genes of breast cancer were identified by utilizing prognostic survival analysis and multivariate Cox hazard proportional regression analysis. Both breast cancer and adjacent normal tissue were collected and analyzed with western blot and immunohistochemistry. Colony formation assay, CCK-8 assay, and EdU assay were used to measure the effect of CBX3 on breast cancer cell growth, wound-healing assay and Transwell assay were used to analyze the effect of CBX3 on breast cancer cell migration and invasion. Flow cytometry assay and western blot were used to study the molecular mechanism of CBX3 in breast cancer. High expression of heterochromatin-related proteins CBX3, H2AFY, and SULF1 showed a poor prognosis in patients in both TCGA dataset and GEO datasets. Western blot demonstrated that the expression level of CBX3 was significantly higher in breast cancer than that in adjacent normal tissues. Colony formation assay, CCK-8 assay, and EdU assay showed that the knockdown of CBX3 could significantly inhibit breast cancer cell growth, and the overexpression of CBX3 could promote the growth of breast cancer cells. Transwell assay and wound healing assay showed that knockdown of CBX3 inhibited breast cancer cell migration and invasion, and the overexpression of CBX3 promoted breast cancer cell migration and invasion. Western blot showed that CBX3 might promote breast cancer cell proliferation, invasion, and migration in breast cancer by modulating the ERK1/2 signaling pathway and epithelial-mesenchymal transition (EMT)-related genes. CBX3 was a biomarker of poor prognosis in breast cancer patients. CBX3 promoted the proliferation of breast cancer cells through the ERK signaling pathway, and migration and invasion of breast cancer cells through EMT-related genes. The CBX3/p-ERK1/2 signaling axis might provide a new therapeutic method against breast cancer.

The Core-Targeted RRM2 Gene of Berberine Hydrochloride Promotes Breast Cancer Cell Migration and Invasion via the Epithelial–Mesenchymal Transition

Berberine hydrochloride (BBR) could inhibit the proliferation, migration, and invasion of various cancer cells. As the only enzyme for the de novo synthesis of ribonucleotides, RRM2 is closely related to the development of tumorigenesis. However, not much is currently known about the functional roles of RRM2 in breast cancer (BRCA), and whether BBR regulates the migration and invasion of BRCA cells by regulating the expression of RRM2 remains to be determined. We study the effects of BBR on BRCA cell proliferation in vitro and tumorigenesis in vivo by using colony formation assays, EdU assays, and xenograft models. Transcriptome sequencing, the random forest algorithm, and KEGG analysis were utilized to explore the therapeutic target genes and relative pathways. The expression of RRM2 in BRCA patients was analyzed with The Cancer Genome Atlas (TCGA) dataset, the GEPIA website tool, the Gene Expression Omnibus (GEO) database, and the UALCAN database. The survival probability of BRCA patients could be predicted by survival curve and nomogram analysis. Molecular docking was used to explore the affinity between BBR and potential targets. Gain- and loss-of-function methods were employed to explore the biological process in RRM2 participants. We comprehensively investigated the pharmacological characteristics of BBR on BRCA cell lines and discovered that BBR could inhibit the proliferation of BRCA cells in vitro and in vivo. Combining transcriptome sequencing and KEGG analysis, we found that BBR mainly affected the biological behavior of BRCA cells via HIF-1α and AMPK signal pathways. Additionally, by using bioinformatics and molecular docking, we demonstrated that RRM2 plays an oncogenic role in BRCA samples and that it acts as the hub gene of BBR on BRCA cells. Knockdown and overexpression studies indicated that RRM2 promoted BRCA cell migration as well as invasion in vitro by affecting the epithelial-to-mesenchymal transition (EMT). Our study demonstrated the significance of BBR regulating HIF-1α and AMPK signaling pathways in BRCA cells. Moreover, we revealed the carcinogenic role and potential mechanism of RRM2 as a core regulatory factor of BBR in BRCA in controlling BRCA invasion, migration, and EMT, suggesting that RRM2 may be a therapeutic target and prognostic biomarker for BRCA therapy.

Upregulation of SCD1 by ErbB2 via LDHA promotes breast cancer cell migration and invasion.

The incidence of breast cancer ranks at the top of female malignant tumors in China. Metastasis remains the main cause of death among breast cancer patients. The overexpression of ErbB2 is closely related to the metastasis and poor prognosis of breast cancer patients. Therefore, ErbB2 is an important clinical therapeutic target of breast cancer. However, the molecular mechanism of ErbB2 promoting breast cancer metastasis has not been studied clearly. Stearoyl-CoA desaturase 1 (SCD1) is a key enzyme in catalyzing the conversion of saturated fatty acids (SFAs) into monounsaturated fatty acids (MUFAs). SCD1 is overexpressed in breast cancer, and its overexpression is an indicator of poor prognosis in breast cancer patients. However, the role of SCD1 in ErbB2-overexpressing breast cancer metastasis has not been reported. In this study, we investigated the role of SCD1 in the migration and invasion of ErbB2-overexpressing breast cancer cells and its molecular mechanism. First, we demonstrated that ErbB2 upregulates the expression of SCD1. Second, we found that SCD1 and its catalytic product oleic acid played crucial roles in migration and invasion of ErbB2-overexpressing breast cancer cells. Finally, we found that in breast cancer cells, ErbB2 upregulated SCD1 through lactate dehydrogenase A (LDHA). To sum up, upregulation of SCD1 by ErbB2 via LDHA promotes the migration and invasion of breast cancer cells.

E2F1-initiated transcription of PRSS22 promotes breast cancer metastasis by cleaving ANXA1 and activating FPR2/ERK signaling pathway

Breast cancer (BC) is the most common malignant tumor in women worldwide. Metastasis is the main cause of BC-related death. The specific mechanism underlying BC metastasis remains obscure. Recently, PRSS22 was discovered to be involved in tumor development, however, its detailed biological function and regulatory mechanism in BC are unclear. Here, we characterized that PRSS22 expression is upregulated in BC tissues compared with non-tumorous breast tissues. Dual luciferase assays, bioinformatics analyses and chromatin immunoprecipitation (ChIP) assays indicated that transcription factor E2F1 directly binds to the PRSS22 promoter region and activates its transcription. Functionally, upregulation of PRSS22 promoted invasion and metastasis of BC cells in vitro and in vivo, whereas knockdown of PRSS22 inhibited its function. Mechanistically, the combination of PRSS22 and ANXA1 protein in BC cells was first screened by protein mass spectrometry analysis, and then confirmed by co-immunoprecipitation (Co-IP) and western blot assays. Co-overexpression of PRSS22 and ANXA1 could promote BC cell migration and invasion. We further demonstrated that PRSS22 promotes the cleavage of ANXA1 and in turn generates an N-terminal peptide, which initiates the FPR2/ERK signaling axis to increase BC aggressiveness.

Hypoxia promotes the expression of Von Willebrand factor in breast cancer cells by up-regulating the transcription factor YY1 and down-regulating the hsa-miR-424

Von Willebrand factor (VWF), a large glycoprotein with hemostatic properties, is mainly synthesized by megakaryocytes and endothelial cells (ECs). In recent years, studies have found that tumor cells also can produce VWF de novo. Tumor growth is usually accompanied by hypoxic environment, and whether hypoxia will influence von Willebrand factor production in tumor cells is still unknown. In this research, we demonstrated that hypoxia could induce the production of VWF in breast cancer cells (MCF-7 and MDA-MB-231 cell lines), and promoted cell migration as well as angiogenesis. Notably, VWF is a key factor for hypoxia to promote breast cancer cell migration and angiogenesis, and knocking down VWF can attenuate the effects of hypoxia. Further study was conducted on the molecular mechanism to clarify why hypoxia can promote VWF synthesis in breast cancer cells. We found that Yin-Yang 1 (YY1, a transcription factor) had a binding site to the promoter region of VWF, and acted as a transcriptional activator of VWF. Meanwhile, hsa-miR-424 inhibited VWF production by associating with the 3′-UTR of VWF mRNA. Here, we proved that hypoxia up-regulated the transcription factor YY1 and down-regulated hsa-miR-424 to increase the expression level of VWF. Additionally, knockdown of transcription factor YY1 and transfection of hsa-miR-424 mimics had a synergistic effect in reducing hypoxia-induced VWF production of breast cancer cells, cell migration and angiogenesis in vitro.

Suppression of SIN3A by miR-183 Promotes Breast Cancer Metastasis.

SIN3A expression is decreased in metastatic breast cancer in part due to miR-183.

CXCL12 promotes CCR7 ligand-mediated breast cancer cell invasion and migration toward lymphatic vessels.

Chemokines are a family of cytokines that mediate leukocyte trafficking and are involved in tumor cell migration, growth, and progression. Although there is emerging evidence that multiple chemokines are expressed in tumor tissues and that each chemokine induces receptor‐mediated signaling, their collaboration to regulate tumor invasion and lymph node metastasis has not been fully elucidated. In this study, we examined the effect of CXCL12 on the CCR7‐dependent signaling in MDA‐MB‐231 human breast cancer cells to determine the role of CXCL12 and CCR7 ligand chemokines in breast cancer metastasis to lymph nodes. CXCL12 enhanced the CCR7‐dependent in vitro chemotaxis and cell invasion into collagen gels at suboptimal concentrations of CCL21. CXCL12 promoted CCR7 homodimer formation, ligand binding, CCR7 accumulation into membrane ruffles, and cell response at lower concentrations of CCL19. Immunohistochemistry of MDA‐MB‐231–derived xenograft tumors revealed that CXCL12 is primarily located in the pericellular matrix surrounding tumor cells, whereas the CCR7 ligand, CCL21, mainly associates with LYVE‐1+ intratumoral and peritumoral lymphatic vessels. In the three‐dimensional tumor invasion model with lymph networks, CXCL12 stimulation facilitates breast cancer cell migration to CCL21‐reconstituted lymphatic networks. These results indicate that CXCL12/CXCR4 signaling promotes breast cancer cell migration and invasion toward CCR7 ligand–expressing intratumoral lymphatic vessels and supports CCR7 signaling associated with lymph node metastasis.

RNF12 is regulated by AKT phosphorylation and promotes TGF-\u03b2 driven breast cancer metastasis

Transforming growth factor-β (TGF-β) acts as a pro-metastatic factor in advanced breast cancer. RNF12, an E3 ubiquitin ligase, stimulates TGF-β signaling by binding to the inhibitory SMAD7 and inducing its proteasomal degradation. How RNF12 activity is regulated and its exact role in cancer is incompletely understood. Here we report that RNF12 was overexpressed in invasive breast cancers and its high expression correlated with poor prognosis. RNF12 promoted breast cancer cell migration, invasion, and experimental metastasis in zebrafish and murine xenograft models. RNF12 levels were positively associated with the phosphorylated AKT/protein kinase B (PKB) levels, and both displayed significant higher levels in the basal-like subtype compared with the levels in luminal-like subtype of breast cancer cells. Mechanistically, AKT-mediated phosphorylation induced the nuclear localization of RNF12, maintained its stability, and accelerated the degradation of SMAD7 mediated by RNF12. Furthermore, we demonstrated that RNF12 and AKT cooperated functionally in breast cancer cell migration. Notably, RNF12 expression strongly correlated with both phosphorylated AKT and phosphorylated SMAD2 levels in breast cancer tissues. Thus, our results uncovered RNF12 as an important determinant in the crosstalk between the TGF-β and AKT signaling pathways during breast cancer progression.

Doxorubicin promotes breast cancer cell migration and invasion via DCAF13.

DDB1 and CUL4 associated factor 13 (DCAF13) is a substrate receptor in the CUL4‐DDB1 E3 ligase, and its expression is associated with the prognosis of certain cancers. In the present study, we report evidence that DCAF13 is aberrantly overexpressed in human breast cancer and its expression is positively associated with cancer progression. Further analysis showed that the DCAF13 expression level is significantly higher in triple‐negative breast cancer compared to non‐triple‐negative breast cancer, indicating a positive correlation between its expression and the aggressiveness of breast cancer. Subsequent studies revealed that DCAF13 regulates cancer cell migration, invasion and epithelial–mesenchymal transition in human breast cancer, whereas it has no significant impact on breast cancer cell proliferation, cell cycle progressionor apoptosis. Taken together, our results demonstrate that DCAF13 promotes the epithelial–mesenchymal transition in human breast cancer cells, indicating an involvement in breast cancer metastasis. Furthermore, we report that doxorubicin, a widely used chemotherapy drug, increases DCAF13 expression in breast cancer cells, leading to enhanced cancer cell migration and invasion. These results suggest that doxorubicin chemotherapy may increase the risk of metastasis of drug‐resistant breast cancer cells, and future therapeutics targeting DCAF13 may help reduce the risk, especially for patients undergoing chemotherapy.