<p>Long Non-coding RNA BLACAT1 Induces Tamoxifen Resistance in Human Breast Cancer by Regulating miR-503/Bcl-2 Axis</p>
Authors: Yan Tang
Guang Shi
Qiong Yu
Rongfeng Qu
Chunmei Hu
Journal: Cancer Management and Research (2020)
Discipline: CLINICAL MEDICINE
Keywords: Bcl-2; breast cancer; long non-coding RNA BLACAT1; miR-503; tamoxifen resistance.
Affiliations: Department of Hematology and Oncology, The Second Hospital of Jilin University, Changchun 130041, Jilin, People's Republic of China.

Abstract:  Introduction: At present, drug resistance remains a major obstacle for breast cancer (BCa) patients who receive tamoxifen (TAM) chemotherapy. In this study, we aimed to investigate the functional role of long non-coding RNA BLACAT1 in the acquisition of TAM resistance in BCa. Methods: TAM-resistant BCa cells were derived by exposure to 1 μM of TAM for 6 months. The expression levels of BLACAT1 and miR-503 were detected by RT-qPCR analysis. Chemosensitivity of BCa cells to TAM was measured by MTT assay. Apoptosis of BCa cells was detected by flow cytometric analysis, and the expression levels of apoptosis-related proteins were detected by Western blot analysis. The direct binding relation between BLACAT1 and miR-503 was predicted by bioinformatics analysis and verified by dual-luciferase reporter assay. Results: Our findings showed that BLACAT1 was significantly upregulated in TAM-resistant BCa cells (MCF-7/TR and T47D/TR), and BLACAT1 knockdown markedly reduced the TAM resistance in these cells. Importantly, we observed that BLACAT1 might function as a competing endogenous RNA of miR-503 in MCF-7/TR and T47D/TR cells, thereby increasing the expression of oncogenic Bcl-2 protein. Rescue experiments showed that miR-503 inhibition partly blocked the inhibitory effect of BLACAT1 knockdown on TAM resistance of MCF-7/TR and T47D/TR cells. Conclusion: To conclude, this study revealed that overexpressed BLACAT1 induces TAM resistance in human BCa partly by regulating miR-503/Bcl-2 axis, potentially benefiting BCa treatment in the future. 

Retracted: Yes

PubPeer comments:
 Figs 1A, 2C, 4E. ![file] ![file] Each panel contains a halo of regularly-spaced dots, surrounding a central clump with a curious tapestry texture, almost woven in appearance. Perhaps these are instrumentation artefacts of some kind. Is it possible for the authors to upload the raw data files to a data repository somewhere? , 
 Retracted [26 July 2021] . ------------------------ The Editor-in-chief and Publisher of *Cancer Management and Research* wish to retract the published article. Concerns were raised regarding discrepancies in the flow cytometry images used in Figures 1B, 2C and 4E. The authors did respond to our queries but were unable to provide the raw data for their flow cytometry results and could not provide raw data for other aspects of their study, including the western blots. The findings of the study could not be validated and the decision was made to retract the article. The authors agree with this decision. Our decision-making was informed by our policy on publishing ethics and integrity and the COPE guidelines on retraction. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as u201cRetractedu201d. ,