A novel protein encoded by a circular RNA circPPP1R12A promotes tumor pathogenesis and metastasis of colon cancer via Hippo-YAP signaling
Authors: Changping Wu
Lujun Chen
Bin Xu
Jingting Jiang
Zhuojun Zheng
Qi Wang
Qi Zhou
You Zhou
Chen Wu
Xiao Zheng
Wenwei Hu
Journal: Molecular Cancer (2019)
Discipline: MOLECULAR BIOLOGY & GENETICS
Keywords: Circular RNA (circRNA); Colon cancer; Metastasis; Proliferation; Protein coding.
Affiliations: Department of Tumor Biological Treatment, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, People's Republic of China., Jiangsu Engineering Research Center for Tumor Immunotherapy, Changzhou, 213003, People's Republic of China., Institute of Cell Therapy, Soochow University, Changzhou, 213003, People's Republic of China., Department of Hematology, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, People's Republic of China., Department of Oncology, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, People's Republic of China., Department of Tumor Biological Treatment, the Third Affiliated Hospital of Soochow University, Changzhou, 213003, People's Republic of China. ., Jiangsu Engineering Research Center for Tumor Immunotherapy, Changzhou, 213003, People's Republic of China. ., Institute of Cell Therapy, Soochow University, Changzhou, 213003, People's Republic of China. .

Abstract:  Background: It has been well established that circular RNAs (circRNAs) play an important regulatory role during tumor progression. Recent studies have indicated that even though circRNAs generally regulate gene expression through miRNA sponges, they may encode small peptides in tumor pathogenesis. However, it remains largely unexplored whether circRNAs are involved in the tumorigenesis of colon cancer (CC). Methods: The expression profiles of circRNAs in CC tissues were assessed by circRNA microarray. Quantitative real-time PCR, RNase R digestion assay and tissue microarray were used to confirm the existence and expression pattern of circPPP1R12A. The subcellular distribution of circPPP1R12A was analyzed by nuclear mass separation assay and fluorescence in situ hybridization (FISH). SDS-PAGE and LC/MS were employed to evaluate the protein-coding ability of circPPP1R12A. CC cells were stably transfected with lentivirus approach, and cell proliferation, migration and invasion, as well as tumorigenesis and metastasis in nude mice were assessed to clarify the functional roles of circPPP1R12A and its encoded protein circPPP1R12A-73aa. RNA-sequencing and Western blotting analysis were furthered employed to identify the critical signaling pathway regulated by circPPP1R12A-73aa. Results: We firstly screened the expression profiles of human circRNAs in CC tissues and found that the expression of hsa_circ_0000423 (termed as circPPP1R12A) was significantly increased in CC tissues. We also found that circPPP1R12A was mostly localized in the cytoplasm of CC cells. Kaplan-Meier analysis showed that patients with higher levels of circPPP1R12A had a significantly shorter overall survival. By gain- and loss-of-function approaches, the results suggested that circPPP1R12A played a critical role in proliferation, migration and invasion of CC cells. Furthermore, we showed that circPPP1R12A carried an open reading frame (ORF), which encoded a functional protein (termed as circPPP1R12A-73aa). Next, we found that PPP1R12A-C, not circPPP1R12A, promoted the proliferation, migration and invasion abilities of CC in vitro and in vivo. Finally, we identified that circPPP1R12A-73aa promoted the growth and metastasis of CC via activating Hippo-YAP signaling pathway. In addition, the YAP specific inhibitor Peptide 17 dramatically alleviated the promotive effect of circPPP1R12A-73aa on CC cells. Conclusions: In the present study, we illustrated the coding-potential of circRNA circPPP1R12A in the progression of CC. Moreover, we identified that circPPP1R12A-73aa promoted the tumor pathogenesis and metastasis of CC via activating Hippo-YAP signaling pathway. Our findings might provide valuable insights into the development of novel potential therapeutic targets for CC. 

Retracted: No

PubPeer comments:
 The tumors presented in Figure 7a are reused from another article from the same group (Zheng Z et al., 2019; Mol Ther, Figure 8c). They are manipulated and presented as something else. ![file] , 
 Dear Tanganyikensis, Thank you for your comment. After a systematic check of the data, we find a set of tumor image was mislabeled and wrong used in the manuscript during revision and we failed to identify this error in time. We have already contacted the editorial board of Molecular Cancer to make the necessary explanation and enquired for a correction. Thanks again and we will keep updating the status of our contacting with editorial board of Molecular Cancer. ,