Poly(ADP-ribose) glycohydrolase enforces p21 degradation via dePARylation to promote gastric cancer progression
Yangchan Hu, Qimei Bao, Yixing Huang, Yan Wang, Xin Zhao, Junjun Nan, Yuxin Meng, Mingcong Deng, Yuancong Li, Zirui Zhuang, Hanyi He, Dan Zu, Yuke Zhong, Chunkai Zhang, Bing Wang, Ran Li, Yanhua He, Qihan Wang, Min Liu, John A. Tainer, Yin Shi, Xiangdong Cheng, Ji Jing, Zu Ye
Yangchan Hu, Qimei Bao, Yixing Huang, Yan Wang, Xin Zhao, Junjun Nan, Yuxin Meng, Mingcong Deng, Yuancong Li, Zirui Zhuang, Hanyi He, Dan Zu, Yuke Zhong, Chunkai Zhang, Bing Wang, Ran Li, Yanhua He, Qihan Wang, Min Liu, John A. Tainer, Yin Shi, Xiangdong Cheng, Ji Jing, Zu Ye
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Research Article Cell biology Gastroenterology Oncology

Poly(ADP-ribose) glycohydrolase enforces p21 degradation via dePARylation to promote gastric cancer progression

Abstract

Dysregulation of cell cycle checkpoints is a cancer hallmark, with ubiquitination-controlled protein stability playing a pivotal role. Although p21, a key cyclin-dependent kinase inhibitor, is tightly regulated by ubiquitin-mediated degradation, the key upstream modulators of its ubiquitination remain incompletely defined. Here, we identify poly(ADP-ribose) glycohydrolase (PARG) as a regulator of p21 stability in gastric cancer (GC) cells. We show that PARG expression is markedly upregulated in GC tissues and correlates with poor patient prognosis. Functional assays revealed that genetic depletion of PARG triggers G2/M phase arrest and impairs GC cell proliferation. Mechanistically, we demonstrate that PARG loss enhances p21 PARylation, which disrupts its association with E3 ubiquitin ligase, thereby reducing K48-linked ubiquitination and leading to p21 protein stabilization. Moreover, we identify lysine residues K161 and K163 as critical sites for PARG-mediated regulation of p21 ubiquitination. Our findings reveal a posttranslational regulatory axis in which PARG governs cell cycle progression by modulating the PARylation-dependent ubiquitination of p21. These results broaden the understanding of p21 regulation in cancer and highlight PARG as a potential therapeutic target for GC treatment.

Authors

Yangchan Hu, Qimei Bao, Yixing Huang, Yan Wang, Xin Zhao, Junjun Nan, Yuxin Meng, Mingcong Deng, Yuancong Li, Zirui Zhuang, Hanyi He, Dan Zu, Yuke Zhong, Chunkai Zhang, Bing Wang, Ran Li, Yanhua He, Qihan Wang, Min Liu, John A. Tainer, Yin Shi, Xiangdong Cheng, Ji Jing, Zu Ye

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Figure 5

High-throughput screening identifies G C-K as synergistic lethal with PARG loss.

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High-throughput screening identifies G C-K as synergistic lethal with PA...
(A) Flowchart of high-throughput drug screening. (B) Initial screening of the natural product library, n = 3. (C) Secondary screening of the top 10 drugs sensitive to PARG KO cells, n = 3. Compounds 1–10 represent vincristine sulfate, lappaconitine, 4-methylumbelliferone, mupirocin, diosmetin, aloin, uridine, ginsenoside C-K, saikosaponin D, and gracillin, respectively. (D) A CCK-8 assay was used to detect the survival rate of WT and PARG KO HGC27 cells after G C-K treatment, n = 3. After the cells were treated with 30 μM G C-K for 48 hours, they were incubated with CCK-8 assay reagent for 2 hours before detection. (E) Flowchart of PDX model construction. (F) Graph of G C-K-treated PDX model tumors. (G) Statistical graph of the tumor volume growth curve in the PDX model after G C-K treatment, n = 5. (H) Statistical graph of tumor weight in the PDX model after G C-K treatment, n = 5. (I) Graphs of IHC staining for TUNEL, Ki-67 and H&E in PDX tumor tissues; scale bar: 50 μm. (J) Statistical graph of TUNEL-positive cells in tumor tissues; n = 5. (K) Statistical graph of Ki-67–positive cells in tumor tissues, n = 5. (*P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001, ****P ≤ 0.0001, NS, not significant, “C, D, and G by 2-way ANOVA, H, J, and K by 1-way ANOVA. Error bars represent the mean ± SD).