Objectives: Triple negative breast cancer (TNBC) is a subtype of breast cancer with stronger invasion and metastasis, but its specific mechanism of action is still unclear. Tuft1 plays an important regulatory role in the survival of breast cancer cells; however, its role in regulating TNBC metastatic potential has not been well-characterized. Our aim was therefore to systematically study the mechanism of TUFT1 in the metastasis, stemness, and chemoresistance of TNBC and provide new predictors and targets for BC treatment. Methods: We used western blotting and IHC to measure TUFT1and Rac1-GTP expression levels in both human BC samples and cell lines. A combination of shRNA, migration/invasion assays, sphere formation assay, apoptosis assays, nude mouse xenograft tumor model, and GTP activity assays was used for further mechanistic studies. Results: We demonstrated that silencing TUFT1 in TNBC cells significantly inhibited cell metastasis and stemness in vitro . A nude mouse xenograft tumor model revealed that TUFT1 knockdown greatly decreased spontaneous lung metastasis of TNBC tumors. Mechanism studies showed that TUFT1 promoted tumor cell metastasis and stemness by up-regulating the Rac1/β-catenin pathway. Moreover, mechanistic studies indicated that the lack of TUFT1 expression in TNBC cells conferred more sensitive to chemotherapy and increased cell apoptosis via down-regulating the Rac1/β-catenin signaling pathway. Further, TUFT1 expression positively correlated with Rac1-GTP in TNBC samples, and co-expression of TUFT1 and Rac1-GTP predicted poor prognosis in TNBC patients who treated with chemotherapy. Conclusion: Our findings suggest that TUFT1/Rac1/β-catenin pathway may provide a potential target for more effective treatment of TNBC.
Abstract. Astrocyte elevated gene-1 (AEG1) was identified to be overexpressed in breast cancer, and to be associated with the development of breast cancer. In the present study, AEG1 was identified as highly expressed in the MCF-7, MDA-MB-231 and SK-BR-3 breast cancer cell lines and was detected in the MCF-10A normal breast epithelial cell line. The present study established an AEG1-knockdown MCF-7 cell line to investigate the expression status of certain cancer-associated proteins. Western blotting demonstrated that AEG1 may affect cancer cell proliferation and invasion via activating the Wnt/β-catenin signaling pathway, a hypothesis that has been supported by cell function tests. The results of the present study demonstrated that when AEG1 was significantly overexpressed in breast cancer cells it promoted cell proliferation and invasion via activating the Wnt/β-catenin signaling pathway. Therefore, AEG1 may serve as a novel therapeutic target in breast cancer. IntroductionBreast cancer is a common type of malignancy; the incidence of the disease has increased in recent years worldwide, currently ranking first with respect to cancer-associated morbidity in women (1-3). The traditional methods of treatment include surgery, radiotherapy and chemotherapy for patients with advanced breast cancer exhibit poor efficacy (4). Therefore, the development of gene-targeted therapy for breast cancer requires further attention. Previous studies have revealed that numerous genes are involved in the occurrence and development of breast cancer, including cyclin D1, matrix metalloproteinases (MMPs) and E-cadherin (5-8). Astrocyte elevated gene-1 (AEG1) has also been investigated with respect to poor prognosis in breast cancer (9). AEG1 is a potentially crucial mediator of tumor malignancy and a key converging point of a complex network of oncogenic signaling pathways (10-12). Previous studies revealed that the AEG1 gene was significantly overexpressed in a number of types of malignant cells, and is associated with tumorigenesis, proliferation, invasion and metastasis (13,14). Statistics also demonstrated that AEG1 was upregulated in breast cancer tissue and positively correlated with clinical stage and lymph node metastasis (15).The Wnt signaling pathway is one of the most important intracellular signal transduction pathways, and it affects the activated state of multiple effector molecules downstream (16)(17)(18)(19). It is closely associated with a variety of human tumor developments, and serves an important role in breast cancer cell proliferation and invasion (20,21). However, the mechanisms that underlie the activation of the Wnt signaling pathway in various types of breast cancer have yet to be identified. β-catenin has been revealed as a central regulator in the Wnt signaling pathway, and is associated with disease progression and poor prognosis in breast cancer (22). Typically, during activation of the Wnt signaling pathway, β-catenin accumulates in the cytosol at high levels, binds to T-cell factor/lymphoid enhancer fac...
Triple-negative breast cancer (TNBC) is the leading cause of cancer-related death in women. Previous studies indicated that miR-361-5p was downregulated in breast cancer, however, the exact effect of miR-361-5p on TNBC requires further investigation. In the present study, we investigated whether miR-361-5p can act as a tumor suppressor by targeting required for cell differentiation 1 homolog (RQCD1) and inhibiting epidermal growth factor receptor (EGFR)/phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway in TNBC. The expression of miR-361-5p and RQCD1 was determined by quantitative reverse transcription PCR (qRT-PCR) and/or western blot in TNBC and the adjacent tissues. miR-361-5p mimics were constructed and transfected to TNBC cell line MDA-MB-231. Expression of miR-361-5p and mRNA and protein expression of RQCD1, PI3K, Akt, EGFR and matrix metallopeptidase 9 (MMP-9) in MDA-MB-231 were measured by qRT-PCR and/or western blot after transfection. Cell viability was determined by CCK-8 assay. Cell migration and invasion ability were evaluated by scratch and transwell assay respectively. Confirmation of miR-361-5p target was determined by bioinformatics analysis and luciferase reporter assay. Downregulated miR-361-5p and upregulated RQCD1 were observed in tumor tissues. Expression of EGFR, PI3K, Akt and MMP-9 was inhibited in cells treated with miR-361-5p mimics. Transfection of miR-361-5p mimics also inhibited the phosphorylation of EGFR, PI3K, and Akt. Suppressed cell viability, migration, and invasion was found in miR-361-5p mimics groups. Luciferase reporter assay showed that RQCD1 was the target of miR-361-5p. These results indicated that overexpression of miR-361-5p might act as a suppressor in TNBC by targeting RQCD1 to inhibit the EGFR/PI3K/Akt signaling pathway.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.