Suppresses Breast Cancer Growth Research Articles

The therapeutic effect of a novel GAPDH inhibitor in mouse model of breast cancer and efficacy monitoring by molecular imaging

BackgroundBreast cancer is a serious threat to women’s health with high morbidity and mortality. The development of more effective therapies for the treatment of breast cancer is strongly warranted. Growing evidence suggests that targeting glucose metabolism may be a promising cancer treatment strategy. We previously identified a new glyceraldehyde-3-phosphate dehydrogenase (GAPDH) inhibitor, DC-5163, which shows great potential in inhibiting tumor growth. Here, we evaluated the anticancer potential of DC-5163 in breast cancer cells.MethodsThe effects of DC-5163 on breast cancer cells were investigated in vitro and in vivo. Seahorse, glucose uptake, lactate production, and cellular ATP content assays were performed to examine the impact of DC-5163 on cellular glycolysis. Cell viability, colony-forming ability, cell cycle, and apoptosis were assessed by CCK8 assay, colony formation assay, flow cytometry, and immunoblotting respectively. The anticancer activity of DC-5163 in vivo was evaluated in a mouse breast cancer xenograft model.ResultsDC-5163 suppressed aerobic glycolysis and reduced energy supply of breast cancer cells, thereby inhibiting breast cancer cell growth, inducing cell cycle arrest in the G0/G1 phase, and increasing apoptosis. The therapeutic efficacy was assessed using a breast cancer xenograft mouse model. DC-5163 treatment markedly suppressed tumor growth in vivo without inducing evident systemic toxicity. Micro-PET/CT scans revealed a notable reduction in tumor 18F-FDG and 18F-FLT uptake in the DC-5163 treatment group compared to the DMSO control group.ConclusionsOur results suggest that DC-5163 is a promising GAPDH inhibitor for suppressing breast cancer growth without obvious side effects. 18F-FDG and 18F-FLT PET/CT can noninvasively assess the levels of glycolysis and proliferation in tumors following treatment with DC-5163.

GAS5 regulated by FTO-mediated m6A modification suppresses cell proliferation via the IGF2BP2/QKI axis in breast cancer

BackgroundThe lncRNA growth arrest-specific 5 (GAS5) is involved in regulating breast cancer progression. In this study, we aimed to elucidate the function and mechanism of GAS5 in breast cancer.MethodsThe expressions of GAS5, fat mass and obesity-associated protein (FTO), insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2), and Quaking (QKI) were assessed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blot. The m6A modification level of GAS5 was detected using m6A immunoprecipitation assay (MeRIP). The interaction between IGF2BP2 and GAS5 or QKI was detected using RNA immunoprecipitation assay (RIP) and dual luciferase reporter assay. Cell proliferation was measured using the Cell Counting Kit-8 (CCK-8) assay. The biological functions of the FTO/GAS5/IGF2BP2/QKI axis was assessed using the tumor xenograft assay.ResultsLncRNA GAS5 expression decreased in breast cancer and was regulated by FTO-mediated m6A modification in an IGF2BP2-dependent manner, resulting in decreased GAS5 stability and expression. GAS5 recruited IGF2BP2 to target QKI and upregulated QKI expression in breast cancer cells. GAS5 suppressed breast cancer growth via IGF2BP2/QKI, and this inhibitory effect was modulated by FTO both in vitro and in vivo.ConclusionsGAS5 regulated by FTO-mediated m6A modification represses the growth of breast cancer via the IGF2BP2/QKI pathway, suggesting that the FTO/GAS5/IGF2BP2/QKI pathway can be a potential target for breast cancer treatment.

In Silico Discovery of Stapled Peptide Inhibitor Targeting the Nur77-PPARγ Interaction and Its Anti-Breast-Cancer Efficacy.

The binding of peroxisome proliferator-activated receptor γ (PPARγ) to the orphan nuclear receptor Nur77 facilitates the ubiquitination and degradation of Nur77, and leads to aberrant fatty acid uptake for breast cancer progression. Because of its crucial role in clinical prognosis, the interaction between Nur77 and PPARγ is an attractive target for anti-breast-cancer therapy. However, developing an inhibitor of the Nur77-PPARγ interaction poses a technical challenge due to the absence of the crystal structure of PPARγ and its corresponding interactive model with Nur77. Here, ST-CY14, a stapled peptide,is identified as a potent modulator of Nur77 with a KD value of 3.247×10-8M by in silico analysis, rational design, and structural modification. ST-CY14 effectively increases Nur77 protein levels by blocking the Nur77-PPARγ interaction, thereby inhibiting lipid metabolism in breast tumor cells. Notably, ST-CY14 significantly suppresses breast cancer growth and bone metastasis in mice. The findings demonstrate the feasibility of exploiting directly Nur77-PPARγ interaction in breast cancer, and generate what to the best knowledge is the first direct inhibitor of the Nur77-PPARγ interaction available for impeding fatty acid uptake and therapeutic development.

Discovery of a far-red carbazole-benzoindolium fluorescent ligand that selectively targets mitochondrial DNA and suppresses breast cancer growth

G-quadruplex (G4) formation was considered to be more prevalent in the mitochondrial DNA (mtDNA) of cancer cells compared with normal cells. Stabilization of these G4s may induce mtDNA instability and cause mitochondrial dysfunction and subsequent cell death, which may be treated as a new strategy for cancer treatment. However, few ligands were developed to target mtG4s, leaving a huge room to improve. In this study, we designed and synthesized a series of carbazole-based ligands, among which, BKN-1 was identified as the most promising mitochondrial targeting fluorescent ligand with far-red emission. Then, we demonstrated that BKN-1 may robustly interact with mtG4s via a variety of biophysical, biological experiments. Subsequently, we proved that BKN-1 may cause mtDNA loss, disrupt mitochondrial integrity, decrease ATP level and trigger unbalanced ROS, thereby leading to apoptosis and autophagy. Finally, we verified that BKN-1 had good anti-tumor activity in both cellular and in vivo models. Altogether, this study provided a dual-function ligand that may not only track the formation of mtG4s but also induce mitochondrial dysfunction, which may be developed into an applicable chemical tool for investigating the structure and function of mtG4s, and moreover, an effective therapeutic agent for cancer interference.

Thrombin induces ferroptosis in triple-negative breast cancer through the cPLA2α/ACSL4 signaling pathway

Ferroptosis is a recently identified form of regulated cell death that plays a crucial role in tumor suppression. In this study, we found that F2 (the gene encoding thrombin) was strongly upregulated in breast cancer (BRCA, TCGA Study Abbreviations) compared with normal samples and that lower F2 levels were associated with poorer prognosis in breast cancer patients. Thrombin induces ferroptosis in triple-negative breast cancer (TNBC) cells by activation of cytosolic phospholipase A2α (cPLA2α) activity to increase the release of arachidonic acid (AA). TNBC in all breast cancer subtypes exhibited the highest levels of PLA2G4A (the gene encoding cPLA2α) and Acsl4, and inhibition of cPLA2α and its downstream enzyme acyl-CoA synthetase long-chain family member 4 (ACSL4) reversed thrombin toxicity. In a mouse xenograft model of TNBC, thrombin treatment suppressed breast cancer growth which can be inhibited by ferroptosis inhibitor Liproxstatin-1 (Lip-1). Our study underscores the potential of the thrombin-ACSL4 axis as a promising therapeutic target for the treatment of TNBC.

Nanoparticle (NP)-mediated APOC1 silencing to inhibit MAPK/ERK and NF-κB pathway and suppress breast cancer growth and metastasis.

Breast cancer is one of the most common malignant tumors with high mortality and poor prognosis in women. There is an urgent need to discover new therapeutic targets for breast cancer metastasis. Herein, we identified that Apolipoprotein C1 (APOC1) was up-regulated in primary tumor of breast cancer patient that recurrence and metastasis by immunohistochemistry (IHC). Kaplan-Meier Plotter database showed that high levels of APOC1 in breast cancer patients were strongly associated with worse overall survival (OS) and relapse-free survival (RFS). Mechanistically, APOC1 silencing significantly inhibits MAPK/ERK kinase pathway and restrains the NF-κB to decrease the transcription of target genes related to growth and metastasis in vitro. Based on this regulatory mechanism, we developed these findings into potential therapeutic drugs, glutathione (GSH) responsive nano-particles (NPs) were used for systemic APOC1 siRNA delivery, NPs (siAPOC1) silenced APOC1 expression, and subsequently resulted in positive anti-tumor effects in orthotopic and liver metastasis models in vivo. Taken together, GSH responsive NP-mediated siAPOC1 delivery was proved to be effective in regulating growth and metastasis in multiple tumor models. These findings show that APOC1 could be a potential biomarker to predict the prognosis of breast cancer patients and NP-mediated APOC1 silencing could be new strategies for exploration of new treatments for breast cancer metastasis.

Nanoparticles (NPs)-mediated lncBCMA silencing to promote eEF1A1 ubiquitination and suppress breast cancer growth and metastasis.

Long non-coding RNAs (lncRNAs) play an important role in cancer metastasis. Exploring metastasis-associated lncRNAs and developing effective strategy for targeted regulation of lncRNA function invivo are of utmost importance for the treatment of metastatic cancer, which however remains a big challenge. Herein, we identified a new functional lncRNA (denoted lncBCMA), which could stabilize the expression of eukaryotic translation elongation factor 1A1 (eEF1A1) via antagonizing its ubiquitination to promote triple-negative breast cancer (TNBC) growth and metastasis. Based on this regulatory mechanism, an endosomal pH-responsive nanoparticle (NP) platform was engineered for systemic lncBCMA siRNA (siBCMA) delivery. This NPs-mediated siBCMA delivery could effectively silence lncBCMA expression and promote eEF1A1 ubiquitination, thereby leading to a significant inhibition of TNBC tumor growth and metastasis. These findings show that lncBCMA could be used as a potential biomarker to predict the prognosis of TNBC patients and NPs-mediated lncBCMA silencing could be an effective strategy for metastatic TNBC treatment.

IGJ suppresses breast cancer growth and metastasis by inhibiting EMT via the NF‑κB signaling pathway.

Breast cancer metastasis is the primary cause of mortality of patients with breast cancer. The present study aimed to explore the role and underlying mechanisms of IGJ in the invasion and metastasis of breast cancer. The Cancer Genome Atlas database was utilized to analyze the differential gene expression profiles in patients with breast cancer with or without metastasis; the target gene, joining chain of multimeric IgA and IgM (JCHAIN, also known as IGJ, as referred to herein), with significant expression and with prognostic value was screened. The expression levels of IGJ in human breast cancer paired tissues and cell lines were detected using reverse transcription‑quantitative PCR and western blot analysis. IGJ differential expression was detected in paired human breast cancer tissues using immunohistochemistry. The role of IGJ in breast cancer was verified using CCK‑8, invasion and migration assays, and scratch tests invivo and invitro. Further exploration of the role and mechanism of IGJ in breast cancer was conducted through Gene Set Enrichment Analysis, Kyoto Encyclopedia of Genes and Genomes analysis, western blot analysis and immunofluorescence experiments. Through the analysis of gene expression profiles, it was found that IGJ was poorly expressed in patients with breast cancer with metastasis compared to patients with non‑metastatic breast cancer. The overexpression of IGJ was associated with an improved distant metastasis‑free survival and overall survival (OS). COX multivariate regression analysis demonstrated that IGJ was an independent prognostic factor for the OS and relapse‑free survival of patients with breast cancer. In comparison to healthy breast cancer adjacent tissues and cell lines, IGJ was poorly expressed in breast cancer tissues and cell lines (P<0.05). Further analyses indicated that the overexpression of IGJ suppressed the proliferation, invasion and metastasis of breast cancer cells in vivo and invitro by inhibiting the occurrence of epithelial‑to‑mesenchymal transition (EMT) and suppressing the nuclear translocation of p65. Finally, rescue experiments indicated that IGJ restricted the proliferation and metastasis of breast cancer cells by regulating the NF‑κB signaling pathway. On the whole, the present study demonstrates that IGJ suppresses the invasion and metastasis of breast cancer by inhibiting both the occurrence of EMT and the NF‑κB signaling pathway. These findings may provide novel biomarkers and potential therapeutic targets for the treatment of metastatic breast cancer.

Chimeric antigen receptor macrophages activated through TLR4 or IFN-γ receptors suppress breast cancer growth by targeting VEGFR2.

Chimeric antigen receptor macrophage (CAR-M) is a promising immunotherapy strategy of anti-tumor due to its high infiltration, direct phagocytosis of tumor cells, immunomodulation of tumor microenvironment (TME) and linkage of innate and adaptive immunity. Here a series of novelly designed CAR-Ms by targeting vascular endothelial growth factor receptor-2 (VEGFR2), which highly expressed in tumor cells and TME, were evaluated. Their activation signals were transduced by Tlr4 or Ifn-γ receptors either alone or in combination, which were designed to mediate M1 polarization of macrophages as the downstream of lipopolysaccharide or Ifn-γ that had been widely reported. Our results showed that VEGFR2-targeting CAR-Ms could be activated under the stimulation of VEGFR2-expressing cells. They exhibited higher expression of CD86, MHCII and TNF-α in vitro and enhanced tumor suppressive abilities in vivo. Implantation of these CAR-Ms into 4T1 breast cancer-bearing mice could obviously inhibit the progression of tumor without significant toxic side effects, especially the group of mmC in which constructed with Tlr4 as the intracellular domain of CAR. In conclusion, this research provides a promising design of CAR that induce macrophages activation by Tlr4 and/or Ifn-γ receptors, and these CAR-Ms could effectively inhibit tumor growth through targeting VEGFR2.

Garcinone E suppresses breast cancer growth and metastasis by modulating tumor-associated macrophages polarization via STAT6 signaling.

Cancer metastasis remains the most common cause of death in breast cancer patients. Tumor-associated macrophages (TAMs) are a novel therapeutic target for the treatment of metastatic breast cancer. Despite the good anti-cancer activity of garcinone E (GE), there are no reports on its therapeutic effects on breast cancer metastasis. The objective of this study was to examine the anti-cancer effects of GE on metastatic breast cancer. RAW 264.7 and THP-1 cells were polarized to M2 macrophages by IL-4/IL-13 in vitro. A 4T1 mouse breast cancer model and the tail vein breast cancer metastasis model were used to explore the effect of GE on breast cancer growth and metastasis in vivo. In vitro studies showed that GE dose-dependently suppressed IL-4 + IL-13-induced expression of CD206 in both RAW 264.7 cells and differentiated THP-1 macrophages. However, GE did not affect the LPS + IFN-γ-induced polarization to the M1-like macrophages in vitro. GE inhibited the expression of the M2 macrophage specific genes in RAW 264.7 cells, and simultaneously impaired M2 macrophage-induced breast cancer cell proliferation and migration, and angiogenesis. In animal studies, GE significantly suppressed tumor growth, angiogenesis, and lung metastasis in 4T1 tumor-bearing mice, without causing toxicity. In both tumor and lung tissues, the proportion of M2-like TAMs was significantly decreased while the proportion of M1-like TAMs was markedly increased by GE treatment. Mechanistically, GE inhibited phosphorylation of STAT6 in vitro and in vivo. Our results demonstrate for the first time that GE suppresses breast cancer growth and pulmonary metastasis by modulating M2-like macrophage polarization through the STAT6 signaling pathway.

ZNF133 is a potent suppressor in breast carcinogenesis through dampening L1CAM, a driver for tumor progression.

Due to the complexity and heterogeneity of breast cancer, the therapeutic effects of breast cancer treatment vary between subtypes. Breast cancer subtypes are classified based on the presence of molecular markers for estrogen or progesterone receptors and human epidermal growth factor 2. Thus, novel, comprehensive, and precise molecular indicators in breast carcinogenesis are urgently needed. Here, we report that ZNF133, a zinc-finger protein, is negatively associated with poor survival and advanced pathological staging of breast carcinomas. Moreover, ZNF133 is a transcription repressor physically associated with the KAP1 complex. It transcriptionally represses a cohort of genes, including L1CAM, that are critically involved in cell proliferation and motility. We also demonstrate that the ZNF133/KAP1 complex inhibits the proliferation and invasion of breast cancer cells in vitro and suppresses breast cancer growth and metastasis in vivo by dampening the transcription of L1CAM. Taken together, the findings of our study confirm the value of ZNF133 and L1CAM levels in the diagnosis and prognosis of breast cancer, contribute to a deeper understanding of the regulation mechanism of ZNF133 for the first time, and provide a new therapeutic strategy and precise intervention target for breast cancer.

S100A6 inhibits MDM2 to suppress breast cancer growth and enhance sensitivity to chemotherapy

BackgroundS100A6 and murine double minute 2 (MDM2) are important cancer-related molecules. A previous study identified an interaction between S100A6 and MDM2 by size exclusion chromatography and surface plasmon resonance experiments. The present study investigated whether S100A6 could bind to MDM2 in vivo and further explored its functional implication.MethodsCo-immunoprecipitation, glutathione-S-transferase pull-down assay, and immunofluorescence were performed to determine the in vivo interaction between S100A6 and MDM2. Cycloheximide pulse-chase assay and ubiquitination assay were performed to clarify the mechanism by which S100A6 downregulated MDM2. In addition, clonogenic assay, WST-1 assay, and flow cytometry of apoptosis and the cell cycle were performed and a xenograft model was established to evaluate the effects of the S100A6/MDM2 interaction on growth and paclitaxel-induced chemosensitivity of breast cancer. The expressions of S100A6 and MDM2 in patients with invasive breast cancer were analyzed by immunohistochemistry. In addition, the correlation between the expression of S100A6 and the response to neoadjuvant chemotherapy was statistically analyzed.ResultsS100A6 promoted the MDM2 translocation from nucleus to cytoplasm, in which the S100A6 bound to the binding site of the herpesvirus-associated ubiquitin-specific protease (HAUSP) in MDM2, disrupted the MDM2–HAUSP–DAXX interactions, and induced the MDM2 self-ubiquitination and degradation. Furthermore, the S100A6-mediated MDM2 degradation suppressed the growth of breast cancer and enhanced its sensitivity to paclitaxel both in vitro and in vivo. For patients with invasive breast cancer who received epirubicin and cyclophosphamide followed by docetaxel (EC-T), expressions of S100A6 and MDM2 were negatively correlated, and high expression of S100A6 suggested a higher rate of pathologic complete response (pCR). Univariate and multivariate analyses showed that the high expression of S100A6 was an independent predictor of pCR.ConclusionThese results reveal a novel function for S100A6 in downregulating MDM2, which directly enhances sensitivity to chemotherapy.

CHMP4A stimulates CD8+ T-lymphocyte infiltration and inhibits breast tumor growth via the LSD1/IFNβ axis.

CD8+ T lymphocyte-mediated immunity strategies have represented attractive weapons against breast cancer (BC) recently. However, the mechanisms underlying CD8+ T-lymphocyte infiltration still remain obscure. Here, using bioinformatics analysis, we identified four hub prognostic genes related to CD8+ T-lymphocyte infiltration (CHMP4A, CXCL9, GRHL2, and RPS29), among which CHMP4A was the most significant gene. High CHMP4A mRNA expression was significantly associated with longer overall survival (OS) in BC patients. Functional experiments showed that CHMP4A had the ability to promote CD8+ T-lymphocyte recruitment and infiltration and suppressed BC growth in vitro and in vivo. Mechanistically, CHMP4A stimulates CD8+ T-lymphocyte infiltration by downregulating LSD1 expression, leading to HERV dsRNA accumulation, and promoting IFNβ and its downstream chemokine production. Collectively, CHMP4A is not only a novel positive predictor for prognosis in BC but also a stimulator of CD8+ T-lymphocyte infiltration regulated by the LSD1/IFNβ pathway. This study suggests that CHMP4A may be a novel target for improving the effectiveness of immunotherapy in patients with BC.

Conditional expression of endorepellin in the tumor vasculature attenuates breast cancer growth, angiogenesis and hyaluronan deposition.

The tumor stroma of most solid malignancies is characterized by a pathological accumulation of pro-angiogenic and pro-tumorigenic hyaluronan driving tumorigenesis and metastatic potential. Of all three hyaluronan synthase isoforms, HAS2 is the primary enzyme that promotes the build-up of tumorigenic HA in breast cancer. Previously, we discovered that endorepellin, the angiostatic C-terminal fragment of perlecan, evokes a catabolic mechanism targeting endothelial HAS2 and hyaluronan via autophagic induction. To explore the translational implications of endorepellin in breast cancer, we created a double transgenic, inducible Tie2CreERT2;endorepellin(ER)Ki mouse line that expresses recombinant endorepellin specifically from the endothelium. We investigated the therapeutic effects of recombinant endorepellin overexpression in an orthotopic, syngeneic breast cancer allograft mouse model. First, adenoviral delivery of Cre evoking intratumor expression of endorepellin in ERKi mice suppressed breast cancer growth, peritumor hyaluronan and angiogenesis. Moreover, tamoxifen-induced expression of recombinant endorepellin specifically from the endothelium in Tie2CreERT2;ERKi mice markedly suppressed breast cancer allograft growth, hyaluronan deposition in the tumor proper and perivascular tissues, and tumor angiogenesis. These results provide insight into the tumor suppressing activity of endorepellin at the molecular level and implicate endorepellin as a promising cancer protein therapy that targets hyaluronan in the tumor microenvironment.

Discovery of YH677 as a cancer stemness inhibitor that suppresses triple-negative breast cancer growth and metastasis by regulating the TGFβ signaling pathway

Triple-negative breast cancer (TNBC) has a poor prognosis due to the lack of specific and highly effective therapeutic agents. Cancer stem cells (CSCs) are one of the main factors contributing to TNBC relapse and metastasis. Therefore, targeting CSCs selectively with small molecules is a novel strategy for drug development. In this study, the natural product harmine (HM) was identified as a hit compound from 2632 natural product monomers based on phenotypic screening of a 2D assay and patient-derived organoid (PDO) model that was established from a patient who had multiple drug resistance and various visceral and contralateral breast metastases. Next, harmine was further modified and optimized to obtain a lead compound (YH677) with a tetrahydro-β-carboline scaffold. YH677 showed potent antiproliferative and antimigratory activities against several TNBC cell lines in vitro. In addition, YH677 inhibited epithelial mesenchymal transition (EMT) and stem cell marker expression in a dose-dependent manner. More importantly, YH677 suppressed breast cancer growth and metastasis in orthotopic, metastatic xenograft and patient-derived xenograft (PDX) models in vivo. Mechanistic studies showed that YH677 inhibits the expansion of CSCs by regulating the TGFβ/Smad signaling pathway. These preclinical data provide a basis for the development of YH677 as a lead compound for TNBC treatment.

Glycyrrhetinic acid suppresses breast cancer metastasis by inhibiting M2-like macrophage polarization via activating JNK1/2 signaling

BackgroundBreast cancer metastasis is leading cause of cancer death among women worldwide. Tumor-associated macrophages (TAMs) have been considered as potential targets for treating breast cancer metastasis because they promote tumor growth and development. Glycyrrhetinic acid (GA) is one of the most important phytochemicals of licorice which has shown promising anti-cancer efficacies in pre-clinical trials. However, the regulatory effect of GA on the polarization of TAMs remains elusive. PurposeTo investigate the role of GA in regulating the polarization of M2 macrophages and inhibiting breast cancer metastasis, and to further explore its underlying mechanisms of action. Study DesignIL-4 / IL-13-treated RAW 264.7 and THP-1 cells were used as the M2-polarized macrophages in vitro. A 4T1 mouse breast cancer model and the tail vein breast cancer metastasis model were applied to study the effect of GA on breast cancer growth and metastasis in vivo. ResultsIn vitro studies showed that GA significantly inhibited IL-4 / IL 13-induced M2-like polarization in RAW 264.7 and THP-1 macrophages without affecting M1-like polarization. GA strongly decreased the expression of M2 macrophage markers CD206 and Arg-1, and reduced the levels of the pro-angiogenic molecules VEGF, MMP9, MMP2 and IL-10 in M2 macrophages. GA also increased the phosphorylation of JNK1/2 in M2 macrophages. Moreover, GA significantly suppressed M2 macrophage-induced cell proliferation and migration in 4T1 cancer cells and HUVECs. Interestingly, the inhibitory effects of GA on M2 macrophages were abolished by a JNK inhibitor. Animal studies showed that GA significantly suppressed tumor growth, angiogenesis, and lung metastasis in BALB/c mice bearing breast tumor. In tumor tissues, GA reduced the number of M2 macrophages but elevated the proportion of M1 macrophages, accompanied by activation of JNK signaling. Similar results were found in the tail vein breast cancer metastasis model. ConclusionThis study demonstrated for the first time that GA could effectively suppress breast cancer growth and metastasis by inhibiting macrophage M2 polarization via activating JNK1/2 signaling. These findings indicate that GA could be served as the lead compound for the future development of anti-breast cancer drug.

Coiled-coil domain containing 3 suppresses breast cancer growth by protecting p53 from proteasome-mediated degradation.

Coiled-coil domain containing 3 (CCDC3) was previously shown to regulate liver lipid metabolism as a secretory protein. Here, we report an unexpected intracellular role of CCDC3 as a tumor suppressor in breast cancer (BrC). Bioinformatics datasets analysis showed that CCDC3 is under-expressed in BrCs, while its higher levels are correlated with higher overall survival and lower relapse of cancer patients, and CCDC3 is positively correlated with p53 and its target genes. Ectopic CCDC3 markedly suppressed proliferation, colony formation, and xenograft tumor growth by augmenting p53 activity in BrC cells. Depletion of endogenous CCDC3 by CRISPR-Cas9 increased proliferation and drug resistance of BrC cells by alleviating 5-Fluorouracil (5-FU)-induced p53 level and activity. Mechanistically, CCDC3 bound to the C-termini of p53 and MDM2, consequently stabilizing p53 in the nucleus and impairing MDM2 recruitment of p53 to the 26S proteosome without inhibiting p53 ubiquitination. p53 induced CCDC3 expression by binding to its promoter in BrC cells. Our results unveil a unique mechanism underlying CCDC3 activation of p53 in a positive feedback fashion to suppress BrC growth.

Hsa_circ_0002082 up-regulates Centromere Protein F via abolishing miR-508-3p to promote breast cancer progression.

Circular RNAs (circRNAs) dysregulation has been revealed to function in the pathological processes of cancers. Herein, the role and mechanisms of hsa_circ_0002082 in breast cancer (BC) progression were elucidated. In vivo and in vitro functional experiments were conducted, and the interaction between miR-508-3p and hsa_circ_0002082 or Centromere Protein F (CENPF) was elucidated. Hsa_circ_0002082 expression was higher in BC tissues and cell lines. Functionally, knockdown of hsa_circ_0002082 induced apoptosis and suppressed proliferation and metastasis in BC cells in vitro. Mechanistically, hsa_circ_0002082 targeted miR-508-3p, which was confirmed to be decreased in BC. MiR-508-3p overexpression suppressed BC cell malignant phenotypes, moreover, inhibition of miR-508-3p attenuated the anticancer action of hsa_circ_0002082 silencing on BC cells. Besides that, miR-508-3p targeted CENPF, CENPF was highly expressed in BC, CENPF up-regulation reversed the suppressive impacts of miR-508-3p on BC cell growth and metastasis. Besides, hsa_circ_0002082 silencing impeded BC growth in nude mice. Knockdown of hsa_circ_0002082 suppresses breast cancer growth and metastasis by miR-508-3p/CENPF axis, suggesting that hsa_circ_0002082 may be a promising target for breast cancer treatment.

Valproic acid regulates MIEF1 through MST2-HIPPO to suppress breast cancer growth

AimsTo determine the effects of valproic acid (VPA) on anti-proliferative effects and mitochondrial function in breast cancer cells and the underlying mechanisms involved in the effects, with a focus on signal transduction. Main methodsThe inhibitory effect of valproic acid on breast cancer in vivo and in vitro was evaluated by cellular and animal experiments. Mitochondria-related proteins as well as hippo pathway were monitored by western blotting. The effects of VPA on mitochondrial membrane potential, reactive oxygen species, and apoptosis were confirmed by flow cytometry. In addition, the involvement of hippo pathway in the regulation of mitochondrial function by VPA was verified by XMU-MP-1 (MST2 inhibitor). Key findingsIn this study, we highlight that VPA significantly attenuates mitochondrial function, leading to inhibited cell proliferation and reduced colony formation in MCF-7 and MDA-MB-231 breast cancer cells. Mechanistically, VPA-induced suppression of mitochondrial aerobic respiration was mediated by decreased expression of mitochondrial elongation factor 1 through activation of the hippo pathway, resulting in impaired breast cancer growth. In summary, we uncover a novel mechanism of VPA in regulating mitochondrial aerobic respiration, which is essential for developing an effective approach in breast cancer therapy. SignificanceMitochondrial aerobic respiration and its products are the main sources of energy for tumors; therefore, studying the role of mitochondrial function in tumor cells is significant. VPA has been used as a therapeutic agent for cancer. However, the detail mechanism underlying the effects of VPA on mitochondrial function in breast cancer remains unclear.

LINC00536 knockdown inhibits breast cancer cells proliferation, invasion, and migration through regulation of the miR-4282/centromere protein F axis.

Breast cancer (BC) poses a huge threat to women's health. Growing evidence has shown lncRNAs play critical roles in BC progression. However, the effect of LINC00536 in BC remains unknown. LINC00536, miR-4282, and centromere protein F (CENPF) expressions in BC cells were determined using qPCR assay. Colony formation assay was employed to evaluate the cell proliferation of BC cells. Besides, cell migration and invasion were evaluated using the transwell assay. FISH assay was employed to analyze LINC00536 and miR-4282 locations in BC cells. Additionally, dual luciferase reporter gene assay was performed to verify the binding relationships between LINC00536 and miR-4282, miR-4282 and CENPF. Here, our results displayed that LINC00536 and CENPF were overexpressed in BC cells, while miR-4282 was downregulated. LINC00536 could negatively regulate miR-4282 expression via directly binding to miR-4282. LINC00536 silence suppressed the proliferation, migration, and invasion of BC cells, which was abolished by miR-4282 inhibition. Additionally, miR-4282 could negatively regulate CENPF expression via directly binding to CENPF. MiR-4282 overexpression suppressed BC development, which was abolished by CENPF overexpression. Finally, we proved that LINC00536 silencing suppressed BC growth via regulating the miR-4282/CENPF axis in vivo. Our research displayed that LINC00536 acted as an oncogene in BC. LINC00536-enhanced BC cell proliferation, migration, and invasion. Moreover, LINC00536 functioned as a ceRNA to exert malignant characteristics in BC via the miR-4282-CENPF axis. Collectively, our results demonstrated that the LINC00536-miR-4282-CENPF axis was a critical player in BC development and was a promising target for BC therapy.