Year-end Sale % OFF 
Abstract
Breast cancer (BC) is the most prevalent malignant neoplasm among women and is the fifth most common cause of cancer-associated death worldwide. Acquired chemoresistance driven by genetic and epigenetic alterations is a significant clinical challenge in treating BC. However, the mechanism of BC cell resistance to adriamycin (ADR) remains to be elucidated. In this study, we identified the methyltransferase-like 3/microRNA-221-3p/homeodomain-interacting protein kinase 2/Che-1 (METTL3/miR-221-3p/HIPK2/Che-1) axis as a novel signaling event that may be responsible for resistance of BC cells to ADR. A dual-luciferase reporter gene assay was employed to test the presence of miR-221-3p binding sites in the 3′UTR of HIPK2. Drug resistance was evaluated by immunoblotting multidrug resistance protein 1 (MDR1) and breast cancer resistance protein (BCRP). Cultured ADR-resistant MCF-7 cells were assayed for their half maximal inhibitory concentration (IC50) values and apoptosis using an MTT assay and Annexin V-FITC/PI-labeled flow cytometry, and the cells were then xenografted into nude mice. METTL3 knockdown was shown to reduce the expression of miR-221-3p by reducing pri-miR-221-3p m6A mRNA methylation, thereby reducing the IC50 value of ADR-resistant MCF-7 cells, reducing the expression of MDR1 and BCRP, and inducing apoptosis. Mechanistically, miR-221-3p was demonstrated to negatively regulate HIPK2 and upregulate its direct target Che-1, thus leading to enhanced drug resistance in ADR-resistant MCF-7 cells. In vitro results were reproduced in nude mice xenografted with ADR-resistant MCF-7 cells. Our work elucidates an epigenetic mechanism of acquired chemoresistance in BC, in support of the METTL3/miR-221-3p/HIPK2/Che-1 axis as a therapeutic target for the improvement of chemotherapy.
Highlights
Breast cancer (BC) is the most prevalently diagnosed malignancy in the female population, with 2,088,849 new cases diagnosed and 626,679 deaths reported in 2018 worldwide, accounting for 11.6% and 6.6% of cases and deaths associated with cancer, respectively[1]
Expressed miRNAs (Fig. 1a) between BC and normal breast tissue samples were screened by analyzing miRNA microarray data in the GSE37527, GSE57897 and GSE58027 datasets of the Gene Expression Omnibus (GEO) database, and miR-221-3p was identified by Venn diagram (Fig. 1b) as a common differentially expressed miRNA. miR-221-3p was upregulated in the microarray datasets GSE37527, GSE58027, and GSE57897 (Fig. 1c)
We successfully introduced a miR-2213p-specific inhibitor into MCF-7/ADR cells (Fig. 1e). miR-221-3p inhibitor-treated MCF-7/ADR cells were subjected to MTT assays and Annexin V-fluorescein isothiocyanate (FITC)/Propidium iodide (PI)-labeled flow cytometry
Summary
Breast cancer (BC) is the most prevalently diagnosed malignancy in the female population, with 2,088,849 new cases diagnosed and 626,679 deaths reported in 2018 worldwide, accounting for 11.6% and 6.6% of cases and deaths associated with cancer, respectively[1]. MicroRNAs (miRNAs) emerge as potential noninvasive cancer biomarkers implicated in tumorigenesis as well as drug resistance and metastasis considering their aberrant expression profile[5]. HIPK2 has been found to downregulate the expression of Che-1/AATF (Che-1), a regulator of gene transcription, cellular proliferative potential and resistance to anticancer drugs[11,12]. Multidrug resistance gene 1 (MDR1) and breast cancer resistance protein (BCRP) have been suggested to be of great importance in mediating the drug resistance of patients with BC13. We sought to investigate the communication of METTL3 with BC cell resistance to ADR, involving its crosstalk with the functional axis of miR-221-3p/HIPK2/Che-1 as well as its regulation of the expression of MDR1 and BCRP
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
