Cyclin dependent kinase 9 inhibitor induces transcription-replication conflicts and DNA damage accumulation in breast cancer
Abstract Background Cyclin-dependent kinase 9 (CDK9) is a crucial regulator of transcriptional progression of RNA polymerase-II (RNAP2). RNA polymerases trapped in DNA can be a source of transcription-replication conflict (T-R conflict), which is a common source of replication stress. AZD4573, a hig...
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BMC
2025-07-01
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| Series: | Cancer Cell International |
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| Online Access: | https://doi.org/10.1186/s12935-025-03897-6 |
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| author | Minyoung Lee Kyung-Hun Lee Ahrum Min So Hyeon Kim Sujin Ham Hae Min Hwang Youlim Noh Yu-Jin Kim Dae-Won Lee Jiwon Koh Seock-Ah Im |
| author_facet | Minyoung Lee Kyung-Hun Lee Ahrum Min So Hyeon Kim Sujin Ham Hae Min Hwang Youlim Noh Yu-Jin Kim Dae-Won Lee Jiwon Koh Seock-Ah Im |
| author_sort | Minyoung Lee |
| collection | DOAJ |
| description | Abstract Background Cyclin-dependent kinase 9 (CDK9) is a crucial regulator of transcriptional progression of RNA polymerase-II (RNAP2). RNA polymerases trapped in DNA can be a source of transcription-replication conflict (T-R conflict), which is a common source of replication stress. AZD4573, a highly selective CDK9 inhibitor, has been shown to induce apoptosis in leukemia cell lines, while its anti-tumor potential in breast cancer has yet to be elucidated. Methods To evaluate the cytotoxicity of AZD4573 in vitro, MTT assays were performed. The expression of signal transduction molecules was determined using Western blotting, immunoprecipitation, and immunofluorescence. Apoptotic cell death was verified by the annexin-V assay. DNA strand breaks and repair efficacy were evaluated through the alkaline comet assay. The siRNA knock-down system was used to confirm the action mechanism. Results AZD4573 induced T-R conflicts during S-phase, increasing replication stress and DNA strand breaks, resulting in apoptosis by induction of caspase-3. Furthermore, we identified Dead-box 25 (DDX25) helicase as a key mediator in resolving the T-R conflicts. Nuclear translocation of DDX25 correlated with reduced sensitivity to AZD4573 by the resolution of T-R conflicts. Conclusions Inhibition of CDK9 by AZD4573 induces the accumulation of DNA damage through T-R conflicts. DDX25 helicases were identified as a key mediator in resolving T-R conflicts and the reduced sensitivity to AZD4573. |
| format | Article |
| id | doaj-art-d98e1e4b87a44e3a86af5b7de8e17615 |
| institution | Kabale University |
| issn | 1475-2867 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | BMC |
| record_format | Article |
| series | Cancer Cell International |
| spelling | doaj-art-d98e1e4b87a44e3a86af5b7de8e176152025-08-20T03:46:16ZengBMCCancer Cell International1475-28672025-07-0125111410.1186/s12935-025-03897-6Cyclin dependent kinase 9 inhibitor induces transcription-replication conflicts and DNA damage accumulation in breast cancerMinyoung Lee0Kyung-Hun Lee1Ahrum Min2So Hyeon Kim3Sujin Ham4Hae Min Hwang5Youlim Noh6Yu-Jin Kim7Dae-Won Lee8Jiwon Koh9Seock-Ah Im10Cancer Research Institute, Seoul National UniversityCancer Research Institute, Seoul National UniversityCancer Research Institute, Seoul National UniversityCancer Research Institute, Seoul National UniversityCancer Research Institute, Seoul National UniversityCancer Research Institute, Seoul National UniversityCancer Research Institute, Seoul National UniversityCancer Research Institute, Seoul National UniversityCancer Research Institute, Seoul National UniversityCancer Research Institute, Seoul National UniversityCancer Research Institute, Seoul National UniversityAbstract Background Cyclin-dependent kinase 9 (CDK9) is a crucial regulator of transcriptional progression of RNA polymerase-II (RNAP2). RNA polymerases trapped in DNA can be a source of transcription-replication conflict (T-R conflict), which is a common source of replication stress. AZD4573, a highly selective CDK9 inhibitor, has been shown to induce apoptosis in leukemia cell lines, while its anti-tumor potential in breast cancer has yet to be elucidated. Methods To evaluate the cytotoxicity of AZD4573 in vitro, MTT assays were performed. The expression of signal transduction molecules was determined using Western blotting, immunoprecipitation, and immunofluorescence. Apoptotic cell death was verified by the annexin-V assay. DNA strand breaks and repair efficacy were evaluated through the alkaline comet assay. The siRNA knock-down system was used to confirm the action mechanism. Results AZD4573 induced T-R conflicts during S-phase, increasing replication stress and DNA strand breaks, resulting in apoptosis by induction of caspase-3. Furthermore, we identified Dead-box 25 (DDX25) helicase as a key mediator in resolving the T-R conflicts. Nuclear translocation of DDX25 correlated with reduced sensitivity to AZD4573 by the resolution of T-R conflicts. Conclusions Inhibition of CDK9 by AZD4573 induces the accumulation of DNA damage through T-R conflicts. DDX25 helicases were identified as a key mediator in resolving T-R conflicts and the reduced sensitivity to AZD4573.https://doi.org/10.1186/s12935-025-03897-6Breast cancerCyclin dependent kinase 9DNA damageTranscription-replication conflict |
| spellingShingle | Minyoung Lee Kyung-Hun Lee Ahrum Min So Hyeon Kim Sujin Ham Hae Min Hwang Youlim Noh Yu-Jin Kim Dae-Won Lee Jiwon Koh Seock-Ah Im Cyclin dependent kinase 9 inhibitor induces transcription-replication conflicts and DNA damage accumulation in breast cancer Cancer Cell International Breast cancer Cyclin dependent kinase 9 DNA damage Transcription-replication conflict |
| title | Cyclin dependent kinase 9 inhibitor induces transcription-replication conflicts and DNA damage accumulation in breast cancer |
| title_full | Cyclin dependent kinase 9 inhibitor induces transcription-replication conflicts and DNA damage accumulation in breast cancer |
| title_fullStr | Cyclin dependent kinase 9 inhibitor induces transcription-replication conflicts and DNA damage accumulation in breast cancer |
| title_full_unstemmed | Cyclin dependent kinase 9 inhibitor induces transcription-replication conflicts and DNA damage accumulation in breast cancer |
| title_short | Cyclin dependent kinase 9 inhibitor induces transcription-replication conflicts and DNA damage accumulation in breast cancer |
| title_sort | cyclin dependent kinase 9 inhibitor induces transcription replication conflicts and dna damage accumulation in breast cancer |
| topic | Breast cancer Cyclin dependent kinase 9 DNA damage Transcription-replication conflict |
| url | https://doi.org/10.1186/s12935-025-03897-6 |
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