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Du M, Wang M, Liu M, Fu S, Lin Y, Huo Y, Yu J, Yu X, Wang C, Xiao H, Wang L. C/EBPα-p30 confers AML cell susceptibility to the terminal unfolded protein response and resistance to Venetoclax by activating DDIT3 transcription. J Exp Clin Cancer Res 2024; 43:79. [PMID: 38475919 DOI: 10.1186/s13046-024-02975-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 02/04/2024] [Indexed: 03/14/2024] Open
Abstract
BACKGROUND Acute myeloid leukemia (AML) with biallelic (CEBPAbi) as well as single mutations located in the bZIP region is associated with a favorable prognosis, but the underlying mechanisms are still unclear. Here, we propose that two isoforms of C/EBPα regulate DNA damage-inducible transcript 3 (DDIT3) transcription in AML cells corporately, leading to altered susceptibility to endoplasmic reticulum (ER) stress and related drugs. METHODS Human AML cell lines and murine myeloid precursor cell line 32Dcl3 cells were infected with recombinant lentiviruses to knock down CEBPA expression or over-express the two isoforms of C/EBPα. Quantitative real-time PCR and western immunoblotting were employed to determine gene expression levels. Cell apoptosis rates were assessed by flow cytometry. CFU assays were utilized to evaluate the differentiation potential of 32Dcl3 cells. Luciferase reporter analysis, ChIP-seq and ChIP-qPCR were used to validate the transcriptional regulatory ability and affinity of each C/EBPα isoform to specific sites at DDIT3 promoter. Finally, an AML xenograft model was generated to evaluate the in vivo therapeutic effect of agents. RESULTS We found a negative correlation between CEBPA expression and DDIT3 levels in AML cells. After knockdown of CEBPA, DDIT3 expression was upregulated, resulting in increased apoptotic rate of AML cells induced by ER stress. Cebpa knockdown in mouse 32Dcl3 cells also led to impaired cell viability due to upregulation of Ddit3, thereby preventing leukemogenesis since their differentiation was blocked. Then we discovered that the two isoforms of C/EBPα regulate DDIT3 transcription in the opposite way. C/EBPα-p30 upregulated DDIT3 transcription when C/EBPα-p42 downregulated it instead. Both isoforms directly bound to the promoter region of DDIT3. However, C/EBPα-p30 has a unique binding site with stronger affinity than C/EBPα-p42. These findings indicated that balance of two isoforms of C/EBPα maintains protein homeostasis and surveil leukemia, and at least partially explained why AML cells with disrupted C/EBPα-p42 and/or overexpressed C/EBPα-p30 exhibit better response to chemotherapy stress. Additionally, we found that a low C/EBPα p42/p30 ratio induces resistance in AML cells to the BCL2 inhibitor venetoclax since BCL2 is a major target of DDIT3. This resistance can be overcome by combining ER stress inducers, such as tunicamycin and sorafenib in vitro and in vivo. CONCLUSION Our results indicate that AML patients with a low C/EBPα p42/p30 ratio (e.g., CEBPAbi) may not benefit from monotherapy with BCL2 inhibitors. However, this issue can be resolved by combining ER stress inducers.
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Affiliation(s)
- Mengbao Du
- Bone Marrow Transplantation Center of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, No.79 Qingchun Rd., Hangzhou, 310003, Zhejiang Province, People's Republic of China
- Institute of Hematology, Zhejiang University, Hangzhou, China
- Zhejiang Province Engineering Laboratory for Stem Cell and Immunity Therapy, Hangzhou, China
| | - Mowang Wang
- Bone Marrow Transplantation Center of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, No.79 Qingchun Rd., Hangzhou, 310003, Zhejiang Province, People's Republic of China
- Institute of Hematology, Zhejiang University, Hangzhou, China
- Zhejiang Province Engineering Laboratory for Stem Cell and Immunity Therapy, Hangzhou, China
| | - Meng Liu
- Department of Hematological Malignancies Translational Science, Gehr Family Center for Leukemia Research, Hematologic Malignancies and Stem Cell Transplantation Institute, Beckman Research Institute, City of Hope Medical Center, Duarte, CA, USA
| | - Shan Fu
- Bone Marrow Transplantation Center of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, No.79 Qingchun Rd., Hangzhou, 310003, Zhejiang Province, People's Republic of China
| | - Yu Lin
- Bone Marrow Transplantation Center of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, No.79 Qingchun Rd., Hangzhou, 310003, Zhejiang Province, People's Republic of China
- Institute of Hematology, Zhejiang University, Hangzhou, China
- Zhejiang Province Engineering Laboratory for Stem Cell and Immunity Therapy, Hangzhou, China
| | - Yankun Huo
- Hematology Department, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe Dong Rd., Zhengzhou, 450000, Henan Province, People's Republic of China
| | - Jian Yu
- Bone Marrow Transplantation Center of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, No.79 Qingchun Rd., Hangzhou, 310003, Zhejiang Province, People's Republic of China
- Institute of Hematology, Zhejiang University, Hangzhou, China
| | - Xiaohong Yu
- Institute of Hematology, Zhejiang University, Hangzhou, China
- Zhejiang Province Engineering Laboratory for Stem Cell and Immunity Therapy, Hangzhou, China
| | - Chong Wang
- Hematology Department, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe Dong Rd., Zhengzhou, 450000, Henan Province, People's Republic of China.
| | - Haowen Xiao
- Department of Hematology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.
- Institute of Hematology, Zhejiang University, Hangzhou, China.
- Zhejiang Province Engineering Laboratory for Stem Cell and Immunity Therapy, Hangzhou, China.
| | - Limengmeng Wang
- Bone Marrow Transplantation Center of The First Affiliated Hospital & Liangzhu Laboratory, Zhejiang University School of Medicine, No.79 Qingchun Rd., Hangzhou, 310003, Zhejiang Province, People's Republic of China.
- Institute of Hematology, Zhejiang University, Hangzhou, China.
- Zhejiang Province Engineering Laboratory for Stem Cell and Immunity Therapy, Hangzhou, China.
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