Objectives Hepatocellular carcinoma (HCC) is one of the most frequent malignancies and a major leading cause of cancer-related deaths worldwide. Several therapeutic options like sorafenib and regorafenib provide only modest survival benefit to patients with HCC. This study aims to identify novel druggable candidate genes for patients with HCC.
Design A non-biased CRISPR (clustered regularly interspaced short palindromic repeats) loss-of-function genetic screen targeting all known human kinases was performed to identify vulnerabilities of HCC cells. Whole-transcriptome sequencing (RNA-Seq) and bioinformatics analyses were performed to explore the mechanisms of the action of a cyclin-dependent kinase 12 (CDK12) inhibitor in HCC cells. Multiple in vitro and in vivo assays were used to study the synergistic effects of the combination of CDK12 inhibition and sorafenib.
Results We identify CDK12 as critically required for most HCC cell lines. Suppression of CDK12 using short hairpin RNAs (shRNAs) or its inhibition by the covalent small molecule inhibitor THZ531 leads to robust proliferation inhibition. THZ531 preferentially suppresses the expression of DNA repair-related genes and induces strong DNA damage response in HCC cell lines. The combination of THZ531 and sorafenib shows striking synergy by inducing apoptosis or senescence in HCC cells. The synergy between THZ531 and sorafenib may derive from the notion that THZ531 impairs the adaptive responses of HCC cells induced by sorafenib treatment.
Conclusion Our data highlight the potential of CDK12 as a drug target for patients with HCC. The striking synergy of THZ531 and sorafenib suggests a potential combination therapy for this difficult to treat cancer.
- hepatocellular carcinoma
- cancer genetics
- DNA damage
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CW, HW, CL and AdC contributed equally.
Contributors CW, HW, CL and AdC designed the experiments, performed the experiments and data analysis and wrote the article; DG performed the in vivo experiments; GJ provided clinical samples; HJ provided advice for the design of the study; RLB provided advice for CRISPR screen and bioinformatics analysis; WQ and RB are responsible for the conception, design and supervision of the study.
Funding This work was funded by grants from the Dutch Cancer Society (KWF) through the Oncode Institute and the Center for Cancer Genomics (CGC.nl), the National Natural Science Foundation of China (81920108025, 81421001, 81672933 and 81874229), the National Basic Research Program of China (973 Program: 2015CB553905), the National Key Sci-Tech Special Projects of Infectious Diseases of China (2018ZX10732202-002-003), Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support (20181703), Shanghai Municipal Commission of Health and Family Planning (2017YQ064 and 2018YQ20) and Shanghai Rising-Star Program (18QA1403900).
Competing interests None declared.
Patient consent for publication Written informed consent was obtained from each patient.
Ethics approval Ethical approval was obtained from the Eastern Hepatobiliary Hospital Research Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.
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