CircBCBM1 Promotes Breast Cancer Brain Metastasis via miR-125a/BRD4 Axis

Abstract Background: Accumulating evidence indicates that circular RNAs (circRNAs) play critical roles in tumorigenesis and progression of various cancers. We previously identified a novel upregulated circRNA, circBCBM1 (hsa_circ_0001944), in the context of breast cancer brain metastasis. However, the potential biological function and molecular mechanism of circBCBM1 in breast cancer brain metastasis remain largely unknown.Methods: In this reserch, we validated the expression and characterization of circBCBM1 through RT-qPCR, Sanger sequencing, RNase R assay and fluorescence in situ hybridization (FISH). Functional experiments were performed to determine the effect of circBCBM1 on growth and metastasis of 231-BR cells both in vitro and in vivo. The regulatory mechanisms among circBCBM1, miR-125a (has-miR-125a-5p), and BRD4 (bromodomain containing 4) were investigated by RNA immunoprecipitation (RIP), RNA pull-down, luciferase reporter assay and western blot. Results: Our findings demonstrated that circBCBM1 is a stable and cytoplasmic circRNA. Functionally, silencing of circBCBM1 led to decreased proliferation and migration of 231-BR cells whereas elevated circBCBM1 expression showed reverse effects in vitro. These findings were confirmed in vivo in mouse models, as knockdown of circBCBM1 significantly decreased growth and brain metastases of 231-BR cells. Mechanistically, circBCBM1 functions as an endogenous miR-125a sponge to inhibit miR-125a activity, resulting in the upregulation of BRD4 expression and subsequent upregulation of MMP9 (matrix metallopeptidase 9) through Sonic hedgehog (SHH) signaling pathway. Importantly, circBCBM1 was markedly upregulated in the breast cancer brain metastasis cells and clinical tissue and plasma samples; besides, the overexpression of circBCBM1 in primary cancerous tissues was associated with shorter brain metastasis-free survival (BMFS) of breast cancer patients.Conclusions: These findings indicate that circBCBM1 is involved in breast cancer brain metastasis via circBCBM1/miR-125a/BRD4 axis, which sheds light on the pathogenic mechanism of circBCBM1 and provides translational evidence that circBCBM1 may serve as a novel diagnostic or prognostic biomarker and potential therapeutic target for breast cancer brain metastasis.

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Increased Expression of Circular RNA circ_0005230 Indicates Dismal Prognosis in Breast Cancer and Regulates Cell Proliferation and Invasion via miR-618/ CBX8 Signal Pathway

Cellular Physiology and Biochemistry ◽

10.1159/000495675 ◽

2018 ◽

Vol 51 (4) ◽

pp. 1710-1722 ◽

Cited By ~ 33

Author(s):

Yi Xu ◽

Yue Yao ◽

Kaiming Leng ◽

Daolin Ji ◽

Lijun Qu ◽

...

Keyword(s):

Breast Cancer ◽

Circular Rna ◽

Clinical Severity ◽

Luciferase Reporter ◽

Circular Rnas ◽

Dismal Prognosis ◽

Tumorigenesis And Progression ◽

Tissue Specimens

Background/Aims: Circular RNAs (circRNAs) are a class of non-coding RNAs. They have been proved to be critically involved in tumorigenesis and progression of malignancies through competing endogenous RNA (ceRNA) mechanism. Nevertheless, the exploration between circRNAs and pathogenesis of breast cancer (BC) is limited. Previously, circ_0005230 was identified upregulated in BC tissues screened by circRNA microarray. In the present study, we aimed to investigate the expression pattern, functional role, and mechanism of circ_0005230 in BC. Methods: qRT-PCR was conducted to elucidate the expression levels of circ_0005230 in BC tissues and cells. Additionally, the clinical severity and prognostic value were investigated. CCK-8, colony-forming, flow cytometric assays were performed. Animal study was conducted to validate the in vitro data. What’s more, Transwell assays were induced to detect the cell metastatic properties of circ_0005230 exerts in BC cells. Luciferase reporter assay was used to measure the mechanism of circ_0005230. Results: circ_0005230 was overexpressed in BC tissue specimens and cell lines. The overexpression of circ_0005230 was related to adverse phenotypes in the patients with BC. In addition, circ_0005230 could be regarded as a prognostic predictor in BC patients. In vitro and in vivo data demonstrated the cell growth promoting role of circ_0005230. Moreover, circ_0005230 could also promote cell migratory and invasive capacities. For the mechanism investigation, circ_0005230 was proved to be a sponge of miR-618, and expression of miR-618 could regulate CBX8 expression via targeting the 3’UTR of CBX8. Rescue assays also illustrated an oncogenic function of circ_0005230 in BC via acting as a miR-618 sponge to promote CBX8 expression. Conclusion: circ_0005230/miR-618/CBX8 axis might play a key role in BC tumorigenesis and development.

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MiR-211 determines brain metastasis specificity through SOX11/NGN2 axis in triple-negative breast cancer

Oncogene ◽

10.1038/s41388-021-01654-3 ◽

2021 ◽

Author(s):

Jhih-Kai Pan ◽

Cheng-Han Lin ◽

Yao-Lung Kuo ◽

Luo-Ping Ger ◽

Hui-Chuan Cheng ◽

...

Keyword(s):

Breast Cancer ◽

Brain Metastasis ◽

Triple Negative Breast Cancer ◽

Triple Negative ◽

Survival Outcomes ◽

Poor Survival ◽

Breast Cancer Brain Metastasis ◽

High Level

AbstractBrian metastasis, which is diagnosed in 30% of triple-negative breast cancer (TNBC) patients with metastasis, causes poor survival outcomes. Growing evidence has characterized miRNAs involving in breast cancer brain metastasis; however, currently, there is a lack of prognostic plasma-based indicator for brain metastasis. In this study, high level of miR-211 can act as brain metastatic prognostic marker in vivo. High miR-211 drives early and specific brain colonization through enhancing trans-blood–brain barrier (BBB) migration, BBB adherence, and stemness properties of tumor cells and causes poor survival in vivo. SOX11 and NGN2 are the downstream targets of miR-211 and negatively regulate miR-211-mediated TNBC brain metastasis in vitro and in vivo. Most importantly, high miR-211 is correlated with poor survival and brain metastasis in TNBC patients. Our findings suggest that miR-211 may be used as an indicator for TNBC brain metastasis.

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CircWAC induces chemotherapeutic resistance in triple-negative breast cancer by targeting miR-142, upregulating WWP1 and activating the PI3K/AKT pathway

Molecular Cancer ◽

10.1186/s12943-021-01332-8 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Lei Wang ◽

Yehui Zhou ◽

Liang Jiang ◽

Linlin Lu ◽

Tiantian Dai ◽

...

Keyword(s):

Breast Cancer ◽

Triple Negative Breast Cancer ◽

Triple Negative ◽

Luciferase Reporter ◽

Akt Pathway ◽

Circular Rnas ◽

Chemotherapeutic Resistance ◽

Repressive Effect

Abstract Background Chemotherapeutic resistance is the main cause of clinical treatment failure and poor prognosis in triple-negative breast cancer (TNBC). There is no research on chemotherapeutic resistance in TNBC from the perspective of circular RNAs (circRNAs). Methods TNBC-related circRNAs were identified based on the GSE101124 dataset. Quantitative reverse transcription PCR was used to detect the expression level of circWAC in TNBC cells and tissues. Then, in vitro and in vivo functional experiments were performed to evaluate the effects of circWAC in TNBC. Results CircWAC was highly expressed in TNBC and was associated with worse TNBC patient prognosis. Subsequently, it was verified that downregulation of circWAC can increase the sensitivity of TNBC cells to paclitaxel (PTX) in vitro and in vivo. The expression of miR-142 was negatively correlated with circWAC in TNBC. The interaction between circWAC and miR-142 in TNBC cells was confirmed by RNA immunoprecipitation assays, luciferase reporter assays, pulldown assays, and fluorescence in situ hybridization. Mechanistically, circWAC acted as a miR-142 sponge to relieve the repressive effect of miR-142 on its target WWP1. In addition, the overall survival of TNBC patients with high expression of miR-142 was significantly better than that of patients with low expression of miR-142, and these results were verified in public databases. MiR-142 regulated the expression of WWP1 and the activity of the PI3K/AKT pathway. It was confirmed that WWP1 is highly expressed in TNBC and that the prognosis of patients with high WWP1 expression is poor. Conclusions CircWAC/miR-142/WWP1 form a competing endogenous RNA (ceRNA) network to regulate PI3K/AKT signaling activity in TNBC cells and affect the chemosensitivity of cells.

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ADAM22/LGI1 complex as a new actionable target for breast cancer brain metastasis

BMC Medicine ◽

10.1186/s12916-020-01806-4 ◽

2020 ◽

Vol 18 (1) ◽

Author(s):

Sara Charmsaz ◽

Ben Doherty ◽

Sinéad Cocchiglia ◽

Damir Varešlija ◽

Attilio Marino ◽

...

Keyword(s):

Breast Cancer ◽

Metastatic Breast Cancer ◽

Brain Metastasis ◽

In Silico ◽

Ex Vivo ◽

Metastatic Breast ◽

Peptide Mimetic ◽

Breast Cancer Brain Metastasis

Abstract Background Metastatic breast cancer is a major cause of cancer-related deaths in woman. Brain metastasis is a common and devastating site of relapse for several breast cancer molecular subtypes, including oestrogen receptor-positive disease, with life expectancy of less than a year. While efforts have been devoted to developing therapeutics for extra-cranial metastasis, drug penetration of blood–brain barrier (BBB) remains a major clinical challenge. Defining molecular alterations in breast cancer brain metastasis enables the identification of novel actionable targets. Methods Global transcriptomic analysis of matched primary and metastatic patient tumours (n = 35 patients, 70 tumour samples) identified a putative new actionable target for advanced breast cancer which was further validated in vivo and in breast cancer patient tumour tissue (n = 843 patients). A peptide mimetic of the target’s natural ligand was designed in silico and its efficacy assessed in in vitro, ex vivo and in vivo models of breast cancer metastasis. Results Bioinformatic analysis of over-represented pathways in metastatic breast cancer identified ADAM22 as a top ranked member of the ECM-related druggable genome specific to brain metastases. ADAM22 was validated as an actionable target in in vitro, ex vivo and in patient tumour tissue (n = 843 patients). A peptide mimetic of the ADAM22 ligand LGI1, LGI1MIM, was designed in silico. The efficacy of LGI1MIM and its ability to penetrate the BBB were assessed in vitro, ex vivo and in brain metastasis BBB 3D biometric biohybrid models, respectively. Treatment with LGI1MIM in vivo inhibited disease progression, in particular the development of brain metastasis. Conclusion ADAM22 expression in advanced breast cancer supports development of breast cancer brain metastasis. Targeting ADAM22 with a peptide mimetic LGI1MIM represents a new therapeutic option to treat metastatic brain disease.

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MicroRNA-101 Inhibits Growth, Proliferation and Migration and Induces Apoptosis of Breast Cancer Cells by Targeting Sex-Determining Region Y-Box 2

Cellular Physiology and Biochemistry ◽

10.1159/000481445 ◽

2017 ◽

Vol 43 (2) ◽

pp. 717-732 ◽

Cited By ~ 16

Author(s):

Jingjie Wang ◽

Huijuan Zeng ◽

Hanjun Li ◽

Tao Chen ◽

Lulu Wang ◽

...

Keyword(s):

Breast Cancer ◽

Cell Lines ◽

Tnm Classification ◽

Critical Role ◽

Luciferase Reporter ◽

Sox2 Expression ◽

Normal Tissues ◽

And Migration

Background: Increasing evidence has demonstrated that microRNAs play a critical role in breast cancer (BC) progression. microRNA-101 (miR-101) has been considered a tumor suppressive miRNA in different cancer types. This study aimed to investigate miR-101 expression in BC tissues and to investigate its roles in BC progression that are mediated by Sex-determining region Y-box 2 (SOX2), a critical oncogene in various cancers. Methods: qRT-PCR and immunohistochemistry were performed to detect miR-101 and SOX2 expression in BC tissues and paired normal tissues or BC cell lines. MTT, transwell migration, wound healing, colony formation, flow cytometric and xenograft assays were performed to determine the influence of miR-101 and SOX2 on the malignant behaviors of BC cells in vitro and in vivo. Results: miR-101 was significantly downregulated in BC tissues and cell lines. miR-101 overexpression inhibited the malignant behaviors of BC cells, both in vitro and in vivo. miR-101 downregulation had the converse effect. A miR-101 binding site was identified by luciferase reporter assay in the 3’UTR of SOX2. SOX2 was upregulated in BC tissues and cell lines, and its upregulation was associated with lymph node metastasis, pathological grade and TNM classification. SOX2 knockdown mimicked the effects of miR-101 overexpression on the malignant behaviors of BC cells, while SOX2 overexpression mitigated the miR-101-induced inhibition of these effects. Conclusions: Our study revealed that miR-101 plays a critical role in suppressing tumor progression by directly targeting SOX2.

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G9a drives hypoxia-mediated gene repression for breast cancer cell survival and tumorigenesis

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1618706114 ◽

2017 ◽

Vol 114 (27) ◽

pp. 7077-7082 ◽

Cited By ~ 46

Author(s):

Francesco Casciello ◽

Fares Al-Ejeh ◽

Greg Kelly ◽

Donal J. Brennan ◽

Shin Foong Ngiow ◽

...

Keyword(s):

Breast Cancer ◽

Gene Expression ◽

Tumor Growth ◽

Cellular Proliferation ◽

Gene Signature ◽

Breast Cancer Patients ◽

Hypoxic Response ◽

And Migration

G9a is an epigenetic regulator that methylates H3K9, generally causing repression of gene expression, and participates in diverse cellular functions. G9a is genetically deregulated in a variety of tumor types and can silence tumor suppressor genes and, therefore, is important for carcinogenesis. Although hypoxia is recognized to be an adverse factor in tumor growth and metastasis, the role of G9a in regulating gene expression in hypoxia has not been described extensively. Here, we show that G9a protein stability is increased in hypoxia via reduced proline hydroxylation and, hence, inefficient degradation by the proteasome. This inefficiency leads to an increase in H3K9me2 at its target promoters. Blocking the methyltransferase activity of G9a inhibited cellular proliferation and migration in vitro and tumor growth in vivo. Furthermore, an increased level of G9a is a crucial factor in mediating the hypoxic response by down-regulating the expression of specific genes, includingARNTL,CEACAM7,GATA2,HHEX,KLRG1, andOGN. This down-regulation can be rescued by a small molecule inhibitor of G9a. Based on the hypothesis that the changes in gene expression would influence patient outcomes, we have developed a prognostic G9a-suppressed gene signature that can stratify breast cancer patients. Together, our findings provide an insight into the role G9a plays as an epigenetic mediator of hypoxic response, which can be used as a diagnostic marker, and proposes G9a as a therapeutic target for solid cancers.

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TAMI-04. OLFACTORY RECEPTOR 5B21 DRIVES BREAST CANCER BRAIN METASTASIS THROUGH STAT3/NFΚB/CEBPΒ PATHWAY

Neuro-Oncology ◽

10.1093/neuonc/noab196.788 ◽

2021 ◽

Vol 23 (Supplement_6) ◽

pp. vi198-vi199

Author(s):

Mao Li ◽

Markus Schweiger ◽

Daniel Ryan ◽

Ichiro Nakano ◽

Litia Carvalho ◽

...

Keyword(s):

Breast Cancer ◽

Brain Metastasis ◽

Cancer Metastasis ◽

Metastatic Breast ◽

Mesenchymal Transition ◽

Breast Cancer Brain Metastasis ◽

Metastatic Sites ◽

The Brain

Abstract Olfactory receptors (ORs), responsible for the sense of smell, play an essential role in various physiological processes outside the nasal epithelium, including cancer. In breast cancer, however, the expression and function of ORs remain understudied. We established a breast cancer metastasis model by intracardiac injection of MDA-MB-231 (231P) in immunocompromised mice and produced a series of derivative cell lines from developed metastatic sites, including the brain-seeking clone (231Br). We examined the significance of ORs transcript abundance in primary and metastatic breast cancer to different tissues, including the brain, bone, and lung. While 20 OR transcripts were differentially expressed in distant metastases, OR5B21 displayed high expression in all three metastatic sites with respect to the primary tumor, especially in brain metastasis with 13 fold higher than the primary site. Metastatic clones showed distinguishing higher invasion biological characteristics compared to parental cells in vivo and in vitro. Knockdown of OR5B21 significantly decreased the invasion and migration of MDA-MB-231 Brain-seeking metastatic cell as well as metastasis to different organs, including the brain, while overexpression of OR5B21 had the opposite effect. Mechanistically, OR5B21 expression was associated with epithelial to mesenchymal transition through the STAT3/NFkB/CEBPβ signaling pathway. We propose OR5B21 (and potentially other ORs) as a novel oncogene contributing to breast cancer brain metastasis and a potential target for adjuvant therapy.

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circEPSTI1 Acts as a ceRNA to Regulate the Progression of Osteosarcoma

Current Cancer Drug Targets ◽

10.2174/1568009619666191107140948 ◽

2020 ◽

Vol 20 (4) ◽

pp. 288-294 ◽

Cited By ~ 3

Author(s):

Xinyu Tan ◽

Duxun Tan ◽

Haomiao Li ◽

Ye Lin ◽

Zhishen Wen ◽

...

Keyword(s):

Cell Proliferation ◽

Luciferase Reporter ◽

Regulatory Function ◽

Cell Leukaemia ◽

Circular Rnas ◽

Cell Proliferation And Migration ◽

And Migration ◽

Proliferation And Migration

Background: Recent studies have reported the vital roles of circular RNAs (circRNAs) in tumor progression. However, the function and expression profile of most circRNAs in osteosarcoma remain unclear. Methods: We examined the expression of circEPSTI1, a circRNA, in 50 paired adjacent normal tissues and osteosarcoma tissues by qRT-PCR. Then, we further explored the function of circEPSTI1 in osteosarcoma progression in vitro and in vivo. For example, cell proliferation and migration were examined. Some experiments were performed to explore the regulatory function of circEPSTI1 in miRNA and to investigate the potential role of circEPSTI1 in osteosarcoma. Results: We found that circEPSTI1 was significantly upregulated in osteosarcoma. Inhibition of circEPSTI1 suppressed the osteosarcoma cancer cell proliferation and migration in vitro. Dual luciferase reporter assay showed that circEPSTI1 and MCL1 (myeloid cell leukaemia 1) could bind to miR-892b and that MCL1 and circEPSTI1 were targets of miR-892b. Conclusion: Thus, the circEPSTI1-miR-892b-MCL1 axis affected osteosarcoma progression through the miRNA sponging mechanism. circEPSTI1 may serve as a target and biomarker for osteosarcoma treatment.

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Circular RNA circIKBKB promotes breast cancer bone metastasis through sustaining NF-κB/bone remodeling factors signaling

Molecular Cancer ◽

10.1186/s12943-021-01394-8 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Yingru Xu ◽

Shuxia Zhang ◽

Xinyi Liao ◽

Man Li ◽

Suwen Chen ◽

...

Keyword(s):

Breast Cancer ◽

Bone Metastasis ◽

Bone Remodeling ◽

Circular Rna ◽

Luciferase Reporter ◽

Circular Rnas ◽

Metastatic Niche ◽

Breast Cancer Bone Metastasis

Abstract Background Breast cancer (BC) has a marked tendency to spread to the bone, resulting in significant skeletal complications and mortality. Recently, circular RNAs (circRNAs) have been reported to contribute to cancer initiation and progression. However, the function and mechanism of circRNAs in BC bone metastasis (BC-BM) remain largely unknown. Methods Bone-metastatic circRNAs were screened using circRNAs deep sequencing and validated using in situ hybridization in BC tissues with or without bone metastasis. The role of circIKBKB in inducing bone pre-metastatic niche formation and bone metastasis was determined using osteoclastogenesis, immunofluorescence and bone resorption pit assays. The mechanism underlying circIKBKB-mediated activation of NF-κB/bone remodeling factors signaling and EIF4A3-induced circIKBKB were investigated using RNA pull-down, luciferase reporter, chromatin isolation by RNA purification and enzyme-linked immunosorbent assays. Results We identified that a novel circRNA, circIKBKB, was upregulated significantly in bone-metastatic BC tissues. Overexpressing circIKBKB enhanced the capability of BC cells to induce formation of bone pre-metastatic niche dramatically by promoting osteoclastogenesis in vivo and in vitro. Mechanically, circIKBKB activated NF-κB pathway via promoting IKKβ-mediated IκBα phosphorylation, inhibiting IκBα feedback loop and facilitating NF-κB to the promoters of multiple bone remodeling factors. Moreover, EIF4A3, acted acting as a pre-mRNA splicing factor, promoted cyclization of circIKBKB by directly binding to the circIKBKB flanking region. Importantly, treatment with inhibitor eIF4A3-IN-2 reduced circIKBKB expression and inhibited breast cancer bone metastasis effectively. Conclusion We revealed a plausible mechanism for circIKBKB-mediated NF-κB hyperactivation in bone-metastatic BC, which might represent a potential strategy to treat breast cancer bone metastasis.

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CircNOL10 suppresses breast cancer progression by sponging miR-767-5p to regulate SOCS2/JAK/STAT signaling

Journal of Biomedical Science ◽

10.1186/s12929-020-00697-0 ◽

2021 ◽

Vol 28 (1) ◽

Author(s):

Fang Wang ◽

Xiaochun Wang ◽

Jingruo Li ◽

Pengwei Lv ◽

Mingli Han ◽

...

Keyword(s):

Breast Cancer ◽

Cell Proliferation ◽

Cancer Progression ◽

Molecular Mechanisms ◽

Luciferase Reporter ◽

Migration And Invasion ◽

Circular Rnas ◽

Cytokine Signaling

Abstract Background Circular RNAs (circRNAs) have caught increasing attentions and interests for their important involvement in cancer initiation and progression. This study aims to investigate the biological functions of circNOL10 and its potential molecular mechanisms in breast cancer (BC). Materials and methods qRT-PCR and western blot assays were performed to measure the expression of related genes. CCK-8, colony formation, flow cytomerty and transwell assays were used to assess cell proliferation, cell cycle, migration and invasion. RNA pull-down, luciferase reporter and RIP assays were applied to address the potential regulatory mechanism of circNOL10. Results CircNOL10 was down-regulated in BC tissues and cells. Low expression of circNOL10 was associated with larger tumor size, advanced TNM stage, lymph node metastasis and unfavorable prognosis. Overexpression of circNOL10 inhibited cell proliferation, migration, invasion and EMT in vitro and slowed xenograft tumor growth in vivo. Mechanistically, circNOL10 could act as a molecular sponge for miR-767-5p, leading to the up-regulation of suppressors of cytokine signaling 2 (SOCS2) and inactivation of JAK2/STAT5 pathway. Moreover, circNOL10-mediated suppression of malignant phenotypes was attenuated by miR-767-5p. Similar to circNOL10, enforced expression of SOCS2 also resulted in the suppression of cell proliferation and metastasis. Furthermore, knockdown of SOCS2 reversed the tumor-suppressive effect induced by circNOL10. Conclusions CircNOL10 repressed BC development via inactivation of JAK2/STAT5 signaling by regulating miR-767-5p/SOCS2 axis. Our findings offer the possibility of exploiting circNOL10 as a therapeutic and prognostic target for BC patients.

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