Background: The APOBEC3 family of cytidine deaminases mutate the cancer genome in a range of cancer types. Although many studies have documented the downstream effects of APOBEC3 activity through next-generation sequencing, less is known about their upstream regulation. In this study, we sought to identify a molecular basis for APOBEC3 expression and activation. Results: HER2 amplification and PTEN loss promote DNA replication stress and APOBEC3B activity in vitro and correlate with APOBEC3 mutagenesis in vivo. HER2-enriched breast carcinomas display evidence of elevated levels of replication stress-associated DNA damage in vivo. Chemical and cytotoxic induction of replication stress, through aphidicolin, gemcitabine, camptothecin or hydroxyurea exposure, activates transcription of APOBEC3B via an ATR/Chk1-dependent pathway in vitro. APOBEC3B activation can be attenuated through repression of oncogenic signalling, small molecule inhibition of receptor tyrosine kinase signalling and alleviation of replication stress through nucleoside supplementation. Conclusion: These data link oncogene, loss of tumour suppressor gene and drug-induced replication stress with APOBEC3B activity, providing new insights into how cytidine deaminase-induced mutagenesis might be activated in tumourigenesis and limited therapeutically.
Bibliographical noteFunding Information:
C. Swanton is Royal Society Napier Research Professor. This work was supported by the Francis Crick Institute which receives its core funding from Cancer Research UK (FC001169), the UK Medical Research Council (FC001169), and the Wellcome Trust (FC001169); by the UK Medical Research Council (grant reference MR/FC001169 /1); C. Swanton is funded by Cancer Research UK (TRACERx), the CRUK Lung Cancer Centre of Excellence, Stand Up 2 Cancer (SU2C), the Rosetrees Trust, NovoNordisk Foundation (ID 16584), the Prostate Cancer Foundation, the Breast Cancer Research Foundation, the European Research Council (THESEUS) and Support was provided to C. Swanton by the National Institute for Health Research, the University College London Hospitals Biomedical Research Centre, and the Cancer Research UK University College London Experimental Cancer Medicine Centre; NK is funded by the Breast Cancer Research Foundation and Stand Up 2 Cancer. MAC and MD are funded by the Breast Cancer Research Foundation. SV is funded by Stand Up 2 Cancer. GG is funded by the Prostate Cancer Foundation. NM is funded by Cancer Research UK (TRACERx). LPZ is funded by a Cancer Research UK fellowship. Cancer research in the Harris laboratory is supported by grants from the Department of Defense Breast Cancer Research Program (BC121347), Jimmy V Foundation for Cancer Research, Minnesota Ovarian Cancer Alliance and Randy Shaver Cancer Research and Community Fund. RSH is an Investigator of the Howard Hughes Medical Institute. The Bartek laboratory is funded by the Danish Cancer Society, the Novo Nordisk Foundation (grant 16584), the Danish Council for Independent Research (DFF-1331-00262B), The Danish National Research Foundation (DNRF125, project CARD) and the Swedish Research Council and CancerFonden (grant 150733). MIW is funded by a CRUK programme grant to the Cancer Therapeutics Unit (C309/A11566). RR is funded by a Wellcome Trust studentship.
- Genomic instability
- Replication stress
- Somatic mutation