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Abstract Colon cancer is a prevalent malignancy, while recent studies revealed the dys-regulation of Hippo signaling as the important driver for colon cancer progression. Several studies have indicated that post-translational modifications on YAP play crucial roles in both Hippo signaling activity and cancer progression. This raises a puzzling question about why YAP/TAZ, an auto-inhibitory pathway, is frequently over-activated in colon cancer, despite the suppressive cascade of Hippo signaling remaining operational. The protein stability of YAP is subject to a tiny balance between ubiquitination and deubiquitination processes. Through correlation analysis of DUBs (deubiquitinases) expression and Hippo target gene signature in colon cancer samples, we found JOSD1 as a critical deubiquitinase for Hippo signaling and colon cancer progression. JOSD1 could facilitate colon cancer progression and in colon cancer, inhibition of JOSD1 via shRNA has been demonstrated to impede tumorigenesis. Furthermore, molecular mechanism studies have elucidated that JOSD1 enhances the formation of the Hippo/YAP transcriptome by impeding K48-linked polyubiquitination on YAP. ChIP assays have shown that YAP binds to JOSD1’s promoter region, promoting its gene transcription. These results suggest that JOSD1 is involved in both activating and being targeted by the Hippo signaling pathway in colon cancer. Consequently, a positive regulatory loop between JOSD1 and Hippo signaling has been identified, underscoring their interdependence during colon cancer progression. Thus, targeting JOSD1 may represent a promising therapeutic approach for managing colon cancer.

Abstract The dysregulation of Hippo signaling is a crucial factor driving the progression of gastric cancer, making the targeting of the Hippo pathway a promising therapeutic strategy. However, effective drugs targeting the Hippo/YAP axis remain unavailable. Thus, identifying potential therapeutic targets and mechanisms that inhibit the activity of the Hippo/YAP axis in gastric cancer is of paramount importance. The ubiquitination modification of the Hippo/YAP pathway plays a significant role in signaling transduction and cancer progression. In an effort to shed light on effective therapeutic targets, we conducted a screening using a deubiquitinase small interfering RNA library, leading to the identification of USP12 as an important deubiquitinase in the context of Hippo/YAP axis and the progression of gastric cancer. Our bioinformatic analysis further demonstrated a correlation between USP12 and poor survival, as well as a positive association with classical YAP target genes in gastric cancer samples. Notably, USP12 depletion was found to inhibit gastric cancer progression via the Hippo/YAP axis, whereas USP12 overexpression exhibited the opposite effect, promoting gastric cancer growth and enhancing YAP activity. Further studies through immuno-staining and immuno-precipitation assays indicated the nuclear localization of USP12 and its association with YAP to enhance YAP stability. Specifically, our findings revealed that USP12 could inhibit K48-linked poly-ubiquitination of YAP, predominantly at the K315 site. As a result, we have identified a novel regulatory mechanism involving USP12 and Hippo signaling in the progression of gastric cancer, with the potential for blockade of USP12 to materialize as a promising strategy for combating gastric cancer.

Abstract Background The Hippo pathway is crucial in organ size control and tumorigenesis. Dysregulation of the Hippo/YAP axis is commonly observed in gastric cancer, while effective therapeutic targets for the Hippo/YAP axis are lacking. Identification of reliable drug targets and the underlying mechanisms that could inhibit the activity of the Hippo/YAP axis and gastric cancer progression is urgently needed. Methods We used several gastric cancer cell lines and xenograft models and performed immunoblotting, qPCR, and in vivo studies to investigate the function of CXCR7 in gastric cancer progression. Results In our current study, we demonstrate that the membrane receptor CXCR7 (C-X-C chemokine receptor 7) is an important modulator of the Hippo/YAP axis. The activation of CXCR7 could stimulate gastric cancer cell progression through the Hippo/YAP axis in vitro and in vivo, while pharmaceutical inhibition of CXCR7 via ACT-1004–1239 could block tumorigenesis in gastric cancer. Molecular studies revealed that the activation of CXCR7 could dephosphorylate YAP and facilitate YAP nuclear accumulation and transcriptional activation in gastric cancer. CXCR7 functions via G-protein Gαq/11 and Rho GTPase to activate YAP activity. Interestingly, ChIP assays showed that YAP could bind to the promoter region of CXCR7 and facilitate its gene transcription, which indicates that CXCR7 is both the upstream signalling and downstream target of the Hippo/YAP axis in gastric cancer. Conclusion In general, we identified a novel positive feedback loop between CXCR7 and the Hippo/YAP axis, and blockade of CXCR7 could be a plausible strategy for gastric cancer.

Abstract Hepatocellular carcinoma (HCC) is one of the most lethal malignancies worldwide. The Hippo signaling pathway has emerged as a significant suppressive pathway for hepatocellular carcinogenesis. The core components of the Hippo pathway constitute a kinase cascade, which inhibits the functional activation of YAP/TAZ. Interestingly, the overactivation of YAP/TAZ is commonly observed in hepatocellular carcinoma, although the inhibitory kinase cascade of the Hippo pathway is still functional. Recent studies have indicated that the ubiquitin‒proteasome system also plays important roles in modulating Hippo signaling activity. Our DUB (deubiquitinase) siRNA screen showed that USP1 is a critical regulator of Hippo signaling activity. Analysis of TCGA data demonstrated that USP1 expression is elevated in HCC and associated with poor survival in HCC patients. RNA sequencing analysis revealed that USP1 depletion affects Hippo signaling activity in HCC cell lines. Mechanistic assays revealed that USP1 is required for Hippo/TAZ axis activity and HCC progression. USP1 interacted with the WW domain of TAZ, which subsequently enhanced TAZ stability by suppressing K11-linked polyubiquitination of TAZ. Our study identifies a novel mechanism linking USP1 and TAZ in regulating the Hippo pathway and one possible therapeutic target for HCC.

Introduction Gastric cancer (GC) diagnosed in the elderly population has become a serious public health problem worldwide. Given the combined effects of frailty and the consequences of cancer treatment, older individuals with GC are more likely than young patients to suffer from postoperative complications and poor clinical outcomes. Nutrition, functional capacity and psychological state-based multimodal prehabilitation, which is dominated by Enhanced Recovery After Surgery (ERAS) pathway management, has been shown to reduce postoperative complications, promote functional recovery and decrease hospitalisation time in certain malignancies. However, no previous studies have investigated the clinical application of multimodal prehabilitation in frail older patients with GC.Methods and analysis The study is a prospective, multicentre randomised controlled trial in which a total of 368 participants who meet the inclusion criteria will be randomised into either a prehabilitation group or an ERAS group. The prehabilitation group will receive multimodal prehabilitation combined with ERAS at least 2 weeks before the gastrectomy is performed, including physical and respiratory training, nutritional support, and therapy and psychosocial treatment. The ERAS group patients will be treated according to the ERAS pathway. All interventions will be supervised by family members. The primary outcome measures are the incidence and severity of postoperative complications. Secondary outcomes include survival, functional capacity and other short-term postoperative outcomes. Overall, the multimodal prehabilitation protocol may improve functional capacity, reduce the surgical stress response and concomitant systemic inflammation, and potentially modulate the tumour microenvironment to improve short-term and long-term clinical outcomes and patients’ quality of life.Ethics and dissemination All procedures and participating centres of this study were approved by their respective ethics committees (QYFYKYLL 916111920). The final study results will be published separately in peer-reviewed journals.Trial registration number NCT05352802.

Highlights 1. RNF31 restrains cancer cell progression in TNBC. 2. RNF31 regulates YAP protein stability via promoting YAP K48-linked poly-ubiquitination. 3. RNF31 represses immune evasion via suppressing YAP/PD-L1 axis in TNBC.

Abstract Background Triple negative breast cancer (TNBC) is one of the most lethal breast cancer subtypes. Due to a lack of effective therapeutic targets, chemotherapy is still the main medical treatment for TNBC patients. Thus, it is important and necessary to find new therapeutic targets for TNBC. Recent genomic studies implicated the Hippo / Yap signal is over activated in TNBC, manifesting it plays a key role in TNBC carcinogenesis and cancer progression. RBCK1 was firstly identified as an important component for linear ubiquitin assembly complex (LUBAC) and facilitates NFKB signaling in immune response. Further studies showed RBCK1 also facilitated luminal type breast cancer growth and endocrine resistance via trans-activation estrogen receptor alpha. Methods RBCK1 and YAP protein expression levels were measured by western blotting, while the mRNA levels of YAP target genes were measured by RT–PCR. RNA sequencing data were analyzed by Ingenuity Pathway Analysis. Identification of Hippo signaling activity was accomplished with luciferase assays, RT–PCR and western blotting. Protein stability assays and ubiquitin assays were used to detect YAP protein degradation. Ubiquitin-based immunoprecipitation assays were used to detect the specific ubiquitination modification on the YAP protein. Results In our current study, our data revealed an opposite function for RBCK1 in TNBC progression. RBCK1 over-expression inhibited TNBC cell progression in vitro and in vivo, while RBCK1 depletion promoted TNBC cell invasion. The whole genomic expression profiling showed that RBCK1 depletion activated Hippo/YAP axis. RBCK1 depletion increased YAP protein level and Hippo target gene expression in TNBC. The molecular biology studies confirmed that RBCK1 could bind to YAP protein and enhance the stability of YAP protein by promoting YAP K48-linked poly-ubiquitination at several YAP lysine sites (K76, K204 and K321). Conclusion Our study revealed the multi-faced RBCK1 function in different subtypes of breast cancer patients and a promising therapeutic target for TNBC treatment. Video abstract

Highlights 1. DUB1 is an important modulator of Hippo signaling in gastric cancer. 2. DUB1 expression is elevated in human gastric cancer samples and correlates with poor survival in gastric cancer. 3. DUB1 facilitates gastric cancer progression via the Hippo/TAZ axis. 4. DUB1 associates with TAZ and directly inhibits YAP polyubiquitination and degradation.

Abstract Background Breast cancer is the most common cancer in women worldwide. More than 70% of breast cancers are estrogen receptor (ER) alpha positive. Compared with ER alpha-negative breast cancer, which is more aggressive and has a shorter survival time, ER alpha-positive breast cancer could benefit from endocrine therapy. Selective estrogen receptor modulators, such as tamoxifen, are widely used in endocrine therapy. Approximately half of ER alpha-positive breast cancer patients will eventually develop endocrine resistance, making it a major clinical challenge in therapy. Thus, decoding the throughput of estrogen signaling, including the control of ER alpha expression and stability, is critical for the improvement of breast cancer therapeutics. Methods TRIM3 and ER alpha protein expression levels were measured by western blotting, while the mRNA levels of ER alpha target genes were measured by RT–PCR. A CCK-8 assay was used to measure cell viability. RNA sequencing data were analyzed by Ingenuity Pathway Analysis. Identification of ER alpha signaling activity was accomplished with luciferase assays, RT–PCR and western blotting. Protein stability assays and ubiquitin assays were used to detect ER alpha protein degradation. Ubiquitin-based immunoprecipitation assays were used to detect the specific ubiquitination modification on the ER alpha protein. Results In our current study, we found that TRIM3, an E3 ligase, can promote ER alpha signaling activity and breast cancer progression. TRIM3 depletion inhibits breast cancer cell proliferation and migration, while unbiased RNA sequencing data indicated that TRIM3 is required for the activity of estrogen signaling on the -genome-wide scale. The immunoprecipitation assays indicated that TRIM3 associates with ER alpha and promotes its stability, possibly by inducing K63-linked polyubiquitination of ER alpha. In conclusion, our data implicate a nongenomic mechanism by which TRIM3 stabilizes the ER alpha protein to control ER alpha target gene expression linked to breast cancer progression. Conclusion Our study provides a novel posttranslational mechanism in estrogen signaling. Modulation of TRIM3 expression or function could be an interesting approach for breast cancer treatment. Graphical abstract Video abstract

Abstract The tumor suppressor P53 plays critical role in preventing cancer. P53 is rarely mutated and remains functional in luminal-type breast cancer(1). According to current knowledge, wild-type P53 function is tightly controlled by posttranslational modifications, such as ubiquitination. Several ubiquitin ligases have been shown to regulate P53 ubiquitination and protein stability. Here, we report that RNF187, a RING family ubiquitin ligase, facilitates breast cancer growth and inhibits apoptosis by modulating P53 signaling. RNF187 expression was elevated in breast cancer and correlated with breast cancer survival only in the P53 wild-type groups. Bioinformatic analysis showed that the expression of RNF187 was negatively correlated with the expression of P53 target genes, such as IGFBP3 and FAS, in breast cancer. RNF187 depletion inhibited breast cancer growth and facilitated cell death. RNA sequencing analysis indicated that RNF187 could be an important modulator of P53 signaling. Further experiments showed that RNF187 interacts with P53 and promotes its degradation by facilitating its polyubiquitination in breast cancer cells. Interestingly, the in vitro ubiquitin assay showed that RNF187 can directly ubiquitinate P53 in a manner independent of MDM2. These findings reveal a novel direct P53 regulator and a potential therapeutic target for breast cancer.

Primary liver cancer is the sixth most frequently diagnosed cancer worldwide and the third leading cause of cancer-related death. The majority of the primary liver cancer cases are hepatocellular carcinoma and intrahepatic cholangiocarcinoma. Worldwide, there is an increasing incidence of primary liver cancer cases due to multiple risk factors ranging from parasites and viruses to metabolic diseases and lifestyles. Often, patients are diagnosed at advanced stages, depriving them of surgical curability benefits. Moreover, the efficacy of the available chemotherapeutics is limited in advanced stages. Furthermore, tumor metastases and recurrence make primary liver cancer management exceptionally challenging. Thus, exploring the molecular mechanisms for the development and progression of primary liver cancer is critical in improving diagnostic, treatment, prognostication, and surveillance modalities. These mechanisms facilitate the discovery of specific targets that are critical for novel and more efficient treatments. Consequently, the Hippo signaling pathway executing a pivotal role in organogenesis, hemostasis, and regeneration of tissues, regulates liver cells proliferation, and apoptosis. Cell polarity or adhesion molecules and cellular metabolic status are some of the biological activators of the pathway. Thus, understanding the mechanisms exhibited by the Hippo pathway is critical to the development of novel targeted therapies. This study reviews the advances in identifying therapeutic targets and prognostic markers of the Hippo pathway for primary liver cancer in the past six years.

Radical excision by surgery is the main treatment method for gastric cancer and as the surgery develops, the laparoscopic treatment effect on gastric cancer is gradually being verified. The totally laparoscopic gastrectomy (TLG) with natural orifice specimen extraction surgery (NOSES) for gastric cancer has attracted people's attention by avoiding abdominal incision and further reducing surgical injury and provides ideas for the further development of minimally invasive surgical treatment on the basis of laparoscopy. Surgical technique of TLG with natural orifice (vagina) specimen extraction is detailed in the text. We have employed NOSES in 4 cases of TLG in the past year. The visual analogue scale score was low, and all patients had no complications during and after the operation. No recurrence or metastasis was found in the short-term follow-up. TLG with NOSES is feasible and has many advantages such as aesthetics, light post-operative pain.