Lin Zhao1,2, Hong Chen3, QingYi Zhang1, Jin Ma1, Hao Hu4, Lu Xu5. 1. Department of Gastrointestinal Surgery, The First Affiliated Hospital of Soochow University, No. 899, Pinghai Road, Suzhou, 215006, Jiangsu, China. 2. Department of General Surgery, Mudanjiang First People's Hospital, Mudanjiang, 157011, China. 3. Department of General Surgery, Suzhou Dushu Lake Hospital Affiliated to Soochow University, Suzhou, 215000, China. 4. Department of Gastrointestinal Surgery, The First Affiliated Hospital of Soochow University, No. 899, Pinghai Road, Suzhou, 215006, Jiangsu, China. hhsuzhou@126.com. 5. Department of Gastrointestinal Surgery, The First Affiliated Hospital of Soochow University, No. 899, Pinghai Road, Suzhou, 215006, Jiangsu, China. luxu@suda.edu.cn.
Abstract
BACKGROUND: The impact of activating transcription factor 4 (ATF4), differentially expressed in colorectal cancer (CRC), on 5-Fluorouracil (5-FU) chemoresistance has not been fully explained. The purpose of this study is to evaluate the clinical significance of ATF4-mediated microRNA-145 (miR-145)/histone deacetylase 4 (HDAC4)/p53 axis in CRC. METHODS: Initially, the expression of ATF4, miR-145, HDAC4, and p53 in CRC tissues and cells was quantified by RT-qPCR and immunoblotting. Next, luciferase activity and chromatin immunoprecipitation assays were performed to verify the binding affinity among miR-145, ATF4, and HDAC4. Moreover, proliferation, clone formation, and apoptosis in CRC cells treated with 5-FU were assessed after gain- or loss-of-function of ATF4, miR-145, and/or HDAC4. Furthermore, the tumorigenicity and chemoresistance of CRC cells in mice were assayed for validating the in vitro findings. RESULTS: ATF4 and HDAC4 were highly expressed, while miR-145 and p53 were poorly expressed in CRC tissues and cells. miR-145 targeted and negatively regulated HDAC4 to activate p53, and miR-145 expression was suppressed by ATF4. Of note, ATF4 facilitated cell proliferation and clone formation ability and repressed apoptosis to promote autophagy and chemoresistance of CRC cells by regulating the miR-145/HDAC4/p53 axis. In vivo experiment elucidated that ATF4-mediated miR-145/HDAC4/p53 axis enhanced tumorigenesis and resistance of CRC cells to 5-FU. CONCLUSION: In conclusion, ATF4-mediated miR-145 inhibition accelerated autophagy of CRC cells and boosted their resistance to 5-FU via the HDAC4/p53 axis.
BACKGROUND: The impact of activating transcription factor 4 (ATF4), differentially expressed in colorectal cancer (CRC), on 5-Fluorouracil (5-FU) chemoresistance has not been fully explained. The purpose of this study is to evaluate the clinical significance of ATF4-mediated microRNA-145 (miR-145)/histone deacetylase 4 (HDAC4)/p53 axis in CRC. METHODS: Initially, the expression of ATF4, miR-145, HDAC4, and p53 in CRC tissues and cells was quantified by RT-qPCR and immunoblotting. Next, luciferase activity and chromatin immunoprecipitation assays were performed to verify the binding affinity among miR-145, ATF4, and HDAC4. Moreover, proliferation, clone formation, and apoptosis in CRC cells treated with 5-FU were assessed after gain- or loss-of-function of ATF4, miR-145, and/or HDAC4. Furthermore, the tumorigenicity and chemoresistance of CRC cells in mice were assayed for validating the in vitro findings. RESULTS: ATF4 and HDAC4 were highly expressed, while miR-145 and p53 were poorly expressed in CRC tissues and cells. miR-145 targeted and negatively regulated HDAC4 to activate p53, and miR-145 expression was suppressed by ATF4. Of note, ATF4 facilitated cell proliferation and clone formation ability and repressed apoptosis to promote autophagy and chemoresistance of CRC cells by regulating the miR-145/HDAC4/p53 axis. In vivo experiment elucidated that ATF4-mediated miR-145/HDAC4/p53 axis enhanced tumorigenesis and resistance of CRC cells to 5-FU. CONCLUSION: In conclusion, ATF4-mediated miR-145 inhibition accelerated autophagy of CRC cells and boosted their resistance to 5-FU via the HDAC4/p53 axis.
Authors: Abdullah M Alnuqaydan; Bilal Rah; Abdulmajeed G Almutary; Shailender Singh Chauhan Journal: Am J Cancer Res Date: 2020-03-01 Impact factor: 6.166