Exosome-mediated lncRNA AFAP1-AS1 promotes trastuzumab resistance through binding with AUF1 and activating ERBB2 translation
Authors: Jingyi Li
Chao Yu
Pengwei Lu
Xueke Qian
Dongwei Dou
Yunqing Yang
Hui Cao
Xiangke Li
Na Han
Huaying Dong
Mingli Han
Jianguo Hu
Yuanting Gu
Xue Yang
Journal: Molecular Cancer (2020)
Discipline: MOLECULAR BIOLOGY & GENETICS
Keywords: AFAP1-AS1; Breast cancer; ERBB2; Exosome; Trastuzumab resistance.
Affiliations: Department of Breast Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China. ., Department of Breast Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China., Department of Vascular Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China., Department of Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China., Department of General Surgery, University-Town Hospital of Chongqing Medical University, Chongqing, 400016, China., Department of Obstetrics and Gynecology, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, 400010, China., Department of General Surgery, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, No.19 XiuHua Road, Xiuying District, Haikou, 570311, China. .

Abstract:  Background: Although trastuzumab provides significant clinical benefit for HER2-positive breast cancers, responses are limited by the emergence of resistance. Recent evidence suggests that long noncoding RNAs (lncRNAs) play important roles in tumorigenesis and chemoresistance. However, the regulatory mechanism of lncRNAs in trastuzumab resistance is not well established to date. In this research, we identified the differentially expressed lncRNA and investigated its regulatory role in trastuzumab resistance of breast cancer. Methods: LncRNA microarray and qRT-PCR were performed to identify the dysregulated lncRNAs. Transmission electron microscopy, differential ultracentrifugation and qRT-PCR were used to verify the existence of exosomal AFAP1-AS1 (actin filament associated protein 1 antisense RNA 1). Bioinformatics prediction, RNA fluorescence in situ hybridization (RNA-FISH) and immunoprecipitation assays were performed to identify the direct interactions between AFAP1-AS1 and other associated targets, such as AU-binding factor 1 (AUF1) and ERBB2. Finally, a series gain- or loss-functional assays were done to prove the precise role of AFAP1-AS1 in trastuzumab resistance. Results: AFAP1-AS1 was screened out due to its higher expression in trastuzumab-resistant cells compared to sensitive cells. Increased expression of AFAP1-AS1was associate with poorer response and shorter survival time of breast cancer patients. AFAP1-AS1 was upregulated by H3K27ac modification at promoter region, and knockdown of AFAP1-AS1 reversed trastuzumab resistance. Moreover, extracellular AFAP1-AS1 secreted from trastuzumab resistant cells was packaged into exosomes and then disseminated trastuzumab resistance of receipt cells. Mechanically, AFAP1-AS1 was associated with AUF1 protein, which further promoted the translation of ERBB2 without influencing the mRNA level. Conclusion: Exosomal AFAP1-AS1 could induce trastuzumab resistance through associating with AUF1 and promoting ERBB2 translation. Therefore, AFAP1-AS1 level may be useful for prediction of trastuzumab resistance and breast cancer treatment. 

Retracted: Yes

PubPeer comments:
 Too light to be adult Wistar rats. ![file] , 
 Could the authors comment as to why some experiments appear to involve Swiss mice? ![file] ,