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 6

Torso CDW19S and ADRM1Rpn13 accumulation marks HBV-induced HRD subtype.

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Torso CDW19S and ADRM1Rpn13 accumulation marks HBV-induced HRD subtype. ...
(A) ChIP assay (left) for FLAG-tagged CDW19S subunits 2.5 kb from DSB in the presence or absence of HA-tagged HBx expression (right). Quantification was normalized to DDB1 value without HBx expression. (B) Chromatin and soluble nuclear fractionation of indicated proteins upon CPT insult with or without HBx-HA expression. Densitometry for DDB1 from 3 repeats is shown on the right. Results were obtained from identical biological samples immunoblotted from different concentrations of PAGE gels. (C) Enrichment of EXO1 or p-RPA32 loading 2.5 kb distal from DSB with HBx expression or siADRM1Rpn13. (D) HR/SSA repair assay in the presence of HBx or siWDR70 in L02 cells, with or without concomitant siADRM1Rpn13 treatment. (E) Schematic showing the HBx-induced “torso” CDW19S and consequent failure of ADRM1Rpn13 removal. (F) Representative images (left) and counting (right) of 53BP1 IRIF (8 hours after IR) in WDR70-ablated cells. Simultaneous ADRM1Rpn13 silencing was performed as indicated. Scale bar: 10 μm. (G) ChIP showing the inability of siADRM1Rpn13 to restore the DSB loading of p-RPA32 and EXO1 in BRCA1-depleted cells. (H) Parallel comparison of HR/SSA improvement by control siRNA (green) or siADRM1Rpn13 (orange) in BRCA1- and WDR70-depleted cells. P values for multiple-group comparison in B–D, F, and G were calculated by 2-way ANOVA test.