Hepatitis B virus infection disrupts homologous recombination in hepatocellular carcinoma by stabilizing resection inhibitor ADRM1
Ming Zeng, … , Antony M. Carr, Cong Liu
Ming Zeng, … , Antony M. Carr, Cong Liu
Published October 10, 2023
Citation Information: J Clin Invest. 2023;133(23):e171533. https://doi.org/10.1172/JCI171533.
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Research Article Hepatology Virology

Hepatitis B virus infection disrupts homologous recombination in hepatocellular carcinoma by stabilizing resection inhibitor ADRM1

Abstract

Many cancers harbor homologous recombination defects (HRDs). A HRD is a therapeutic target that is being successfully utilized in treatment of breast/ovarian cancer via synthetic lethality. However, canonical HRD caused by BRCAness mutations do not prevail in liver cancer. Here we report a subtype of HRD caused by the perturbation of a proteasome variant (CDW19S) in hepatitis B virus–bearing (HBV-bearing) cells. This amalgamate protein complex contained the 19S proteasome decorated with CRL4WDR70 ubiquitin ligase, and assembled at broken chromatin in a PSMD4Rpn10- and ATM-MDC1-RNF8–dependent manner. CDW19S promoted DNA end processing via segregated modules that promote nuclease activities of MRE11 and EXO1. Contrarily, a proteasomal component, ADRM1Rpn13, inhibited resection and was removed by CRL4WDR70-catalyzed ubiquitination upon commitment of extensive resection. HBx interfered with ADRM1Rpn13 degradation, leading to the imposition of ADRM1Rpn13-dependent resection barrier and consequent viral HRD subtype distinguishable from that caused by BRCA1 defect. Finally, we demonstrated that viral HRD in HBV-associated hepatocellular carcinoma can be exploited to restrict tumor progression. Our work clarifies the underlying mechanism of a virus-induced HRD subtype.

Authors

Ming Zeng, Zizhi Tang, Laifeng Ren, Haibin Wang, Xiaojun Wang, Wenyuan Zhu, Xiaobing Mao, Zeyang Li, Xianming Mo, Jun Chen, Junhong Han, Daochun Kong, Jianguo Ji, Antony M. Carr, Cong Liu

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Figure 1

Interference with CRL4WDR70 by HBx induces a viral HRD.

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Interference with CRL4WDR70 by HBx induces a viral HRD. (A) Repair frequ...
(A) Repair frequency of indicated pathways in WDR70-knockout or HBx-expressing cells relative to control cells (293T). **P <0.05 by 2-tailed t test. NS, no statistic significance. (B) Left: Example confocal images showing 53BP1 (red) and RPA32 (green) IRIF in HBx-expressing L02 cells 8 hours after IR. Soluble nuclear proteins were preextracted with 0.1% Triton X-100. Scale bar: 10 μm. Right: Pixel intensity (vertical) across the maximal central line of individual IRIFs. Precipitation of red line (53BP1) and rising of green line (RPA32) along the vertical axis indicate the central cavity. (C and D) ChIP assay depicting p-RPA32 chromatin loading at indicated distance from the DSB upon expression of gRNA (g1) targeting the PPP1R12C/p84 locus. WDR70-knockout or control 293T cells (C) and L02 cells expressing HBx (D) were cotransfected with si53BP1 or control siRNA (siScr). (E) Relative HR/SSA efficiency for L02 cells pretreated with HBx, siWDR70, or siBRCA1 and concomitant silencing of 53BP1. (F and G) Representative images (F) and quantification (G) of aberrant chromosomes in the indicated cells cotreated with olaparib (1 μM) and/or sh53BP1. (H) Giemsa staining for colony formation (left) and survival curves (right) of control L02 (HBV–) and T43 (HBV+) cells subjected to olaparib treatment. Survival at endpoints was analyzed for statistical significance. n = 3 biological repeats; error bars indicate SD; t test. (I) Survival curves for L02 and T43 cells treated with siWDR70 (left) or sh53BP1 (right) with simultaneous exposure to indicated concentrations of olaparib. n = 3 experimental repeats; error bars indicate SD; P values by t test are shown for indicated groups.