Bairong Xia

USP33 facilitates the ovarian cancer progression via deubiquitinating and stabilizing CBX2

Post-translational modifications of proteins play a pivotal role in both the initiation and progression of ovarian cancer. Despite the recognition of USP33 as a significant factor in various cancers, its specific function and underlying mechanisms in ovarian cancer remain elusive. Proteomics and ubiquitinomics approaches were coupled to screen novel substrate proteins directly regulated by USP33. Our findings unveil that USP33 was observed to eliminate K27- and K48-linked ubiquitin chains from CBX2 at the K277 position. Notably, acetylation of CBX2 at K199, catalyzed by lysine acetyltransferase GCN5, was found to enhance its interaction with USP33, subsequently promoting further deubiquitination and stabilization. Functionally, our experiments demonstrate that USP33 significantly enhances ovarian cancer proliferation and metastasis in a CBX2-dependent manner. Furthermore, analysis revealed a direct positive correlation between the expression levels of USP33 and CBX2 proteins in human specimens, with elevated levels being associated with reduced survival rates in ovarian cancer patients. These findings elucidate the mechanism by which USP33 augments ovarian cancer progression through the stabilization of CBX2, underscoring the USP33-CBX2 axis as a promising therapeutic target in ovarian cancer management.

GSK3β and UCHL3 govern RIPK4 homeostasis via deubiquitination to enhance tumor metastasis in ovarian cancer

Receptor-interacting protein kinase 4 (RIPK4) is increasingly recognized as a pivotal player in ovarian cancer, promoting tumorigenesis and disease progression. Despite its significance, the posttranslational modifications dictating RIPK4 stability in ovarian cancer remain largely uncharted. In this study, we first established that RIPK4 levels are markedly higher in metastatic than in primary ovarian cancer tissues through single-cell sequencing. Subsequently, we identified UCHL3 as a key deubiquitinase that regulates RIPK4. We elucidate the mechanism that UCHL3 interacts with and deubiquitinates RIPK4 at the K469 site, removing the K48-linked ubiquitin chain and thus enhancing RIPK4 stabilization. Intriguingly, inhibition of UCHL3 activity using TCID leads to increased RIPK4 ubiquitination and degradation. Furthermore, we discovered that GSK3β-mediated phosphorylation of RIPK4 at Ser420 enhances its interaction with UCHL3, facilitating further deubiquitination and stabilization. Functionally, RIPK4 was found to drive the proliferation and metastasis of ovarian cancer in a UCHL3-dependent manner both in vitro and in vivo. Importantly, positive correlations between RIPK4 and UCHL3 protein expression levels were observed, with both serving as indicators of poor prognosis in ovarian cancer patients. Overall, this study uncovers a novel pathway wherein GSK3β-induced phosphorylation of RIPK4 strengthens its interaction with UCHL3, leading to increased deubiquitination and stabilization of RIPK4, thereby promoting ovarian cancer metastasis. These findings offer new insights into the molecular underpinnings of ovarian cancer and highlight potential therapeutic targets for enhancing antitumor efficacy.

Evaluation of secondary cytoreduction surgery in platinum-resistant ovarian cancer patients within three-line recurrent: a multicenter, randomized controlled study

Epithelial ovarian cancer is the leading cause of death among gynecological malignancies. Platinum resistance remains a dilemma and bottleneck in treatment, and salvage chemotherapy has limited effectiveness. Recently, the role of secondary cytoreductive surgery (SCS) in patients with platinum-resistant recurrent ovarian cancer (ROC) has caused attention especially in patients with oligometastases. However, there is neither high-quality evidence-based evidence nor standardized criteria for selecting SCS for patients with platinum-resistant ROC until now. This multicenter, randomized, controlled clinical trial is to evaluate the value of SCS and to clarify reliable criteria of utilizing SCS in women with ROC, which is led by Gynecologic Oncology Group, Women's Hospital, Zhejiang University School of Medicine. Recruitment has started on January 1st, 2023, and is scheduled to end in December 2026. One hundred and forty participants with platinum-resistant ROC who meet the "RSCS criteria" will be randomized assigned at a ratio of 1:1 to either the experimental arm or the standard arm. Patients in the experimental arm will receive SCS followed by non-platinum single agent chemotherapy (paclitaxel, gemcitabine or liposomal adriamycin) for at least 4 cycles while patients in the standard arm will be provided with only non-platinum single agent chemotherapy. The primary outcome is progression-free survival. The secondary outcomes are overall survival, adverse events and health-related cancer-specific quality of life. ClinicalTrials.gov Identifier: NCT05633199.

Cytoreductive Surgery in Platinum-resistant Recurrent Ovarian Cancer

This novel study was specifically designed for platinum-resistant recurrent ovarian cancers with PFI\<6 months and aimed to compare prognosis of patients who received cytoreductive surgery followed by chemotherapy versus chemotherapy alone.