Li Honghao,Wu Junfeng,Dai Hua,Li Jiaming,Bai Xiaoyan,Sun Yueli,Lin Jiaxin,Li Yangsi,Li Peng,Shi Lingchao,Wang Zhen,Tu Haiyan,Ke Ee
Indolent lung cancer is characterized by slow progression, and the patient may die of other causes before it becomes symptomatic. The increasing usage of lung cancer screening technologies has increased the detection of early-stage cancers, improved survival, and reduced mortality, but it also brings overdiagnosis or overtreatment for indolent lung cancer patients. In this study, we performed high-throughput whole-exome sequencing in lung adenocarcinoma (LUAD) patients with a tumor doubling time of more than 600 days (the indolent group) and another group with a tumor doubling time of less than 30 days (the aggressive group). We identified a novel germline variation in PDZRN4 , rs74955204 (p.G121E, c.362 G > A) in the indolent group. The rs74955204 variant resulted in upregulated PDZRN4 expression and was positively correlated with the survival of LUAD patients. We confirmed that overexpression of PDZRN4 inhibits the ubiquitylation of HIF-1A mediated by TRIM28, thus activating HIF-1A-IGFBP3 signaling to promote apoptosis, and inducing NDRG1 to inhibit EGFR-AKT signaling, restricting lung cancer cell growth in vitro and in vivo. With the EGFR L858R -driven lung cancer mouse model as an example, we found that PDZRN4 knockout promoted, whereas PDZRN4 overexpression suppressed LUAD growth in vivo. In addition, recombinant PDZRN4 or screened small molecules retinoic acid showed potent inhibitory effects on EGFR-driven LUAD growth and amelioration of osimertinib resistance. Overall, our findings suggest that targeted PDZRN4 is a potential therapeutic strategy for treating LUAD. Examination of PDZRN4 rs74955204 variant may be an effective approach for the early detection of indolent lung cancer and to avoid overdiagnosis. Graphical : Germline variation rs74955204 (p.G121E, c.362 G > A) in PDZRN4 significantly upregulated PDZRN4 expression and resulted in indolent growth of LUAD. Overexpressed PDZRN4 inhibits the ubiquitylation of HIF-1A by TRIM28, activating HIF-1A-IGFBP3 signaling to promote apoptosis, and inducing NDRG1 to inhibit EGFR-AKT signaling, thus restricting lung cancer cell growth.
Background Hepatitis B virus (HBV) is a pathogen that poses a serious threat to human health. The interaction between HBV and host has made great progress in recent years. SUMOylation is involved in virus-related cancer progression, but there are fewer studies on the mechanism of SUMOylation on HBV replication and antiviral defense. Tumor necrosis factor receptor-associated factor 6 (TRAF6) is a critical adaptor of the NF-κB pathways. Here, we focus on the roles of TRIM28 in regulating TRAF6 SUMOylation in HBV-replicating cells. Methods The SUMO1-modified TRAF6 proteins were enriched from total cellular proteins by immunoprecipitation with anti-SUMO1 antibody, then the SUMOylated TRAF6 was detected by western blot using an anti-TRAF6 antibody. The interaction between TRAF6 and TRIM28 was identified by immunoprecipitation and LC–MS/MS. The modification sites of TRAF6 SUMOylation were identified by amino acid site mutation. Expression and localization of TRAF6 and TRIM28 were assessed by immunohistochemistry and immunofluorescence. The hydrodynamic injection HBV mouse model was used to determine the function of TRIM28-mediated TRAF6 SUMOylation in vivo. Results The results show that the levels of SUMO1-modified TRAF6 are elevated in HBV-replicating cells. Lys453 is a major SUMO1 modification site of TRAF6. There is an antagonistic interaction between SUMOylation and ubiquitination of TRAF6 protein. The SUMO ligase TRIM28 is responsible for catalyzing TRAF6 SUMOylation. Compared to the wild-type TRAF6, its SUMO site mutant TRAF6 K453R promotes NF-κB activation. Moreover, TRIM28 overexpression attenuates TRAF6-mediated NF-κB activation, thereby inhibiting HBV replication in vivo. Conclusions Our findings demonstrate that SUMO ligase TRIM28 affects the ability of TRAF6 on NF-κB activation, nucleocytoplasmic shuttling and HBV replication-related indicators. Our data reveal that TRIM28-mediated SUMOylation of TRAF6 is a novel mechanism to regulate the inflammatory response, which may pave the way for new strategies to control anti-HBV.
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