The E3 ubiquitin ligase, FBXW5, promotes the migration and invasion of gastric cancer through the dysregulation of the Hippo pathway

The enigma of maladaptation in gastric pathophysiology

Despite a decline in global incidence, gastric cancer (GC) remains a major health concern. The development of GC is a sequential, multistage maladaptive process involving numerous different factors. Understanding the complexity of GC development is crucial for early detection, effective treatment, and, ultimately, prevention. In this respect, identifying the impact of risk factors contributing to the emergence or progression of GC, such as Helicobacter pylori infection, host and bacterial genetics, alcohol consumption, smoking, and preserved foods, will aid in combatting this disease. In this review, we focus on recent developments in understanding the role of the microbiome, dysfunctional molecular pathways, and immune evasion in gastric pathophysiology. We also highlight challenges and advances in treatment of GC.

F-box/WD Repeat-Containing Protein 5 Promotes Breast Cancer Progression by Regulating Ferroptosis via Enhancing Krüppel-like Factor 13 Ubiquitination Through Phosphoinositide 3-Kinase/Serine/Threonine Protein Kinase Pathway

Breast cancer (BC) is a prevalent malignancy among women. Evidence has indicated that F-box/WD repeat-containing protein 5 (FBXW5) is crucial in oncogenesis and progression. However, the function of FBXW5 in BC remains elusive. This work aims to explore the regulatory mechanisms of FBXW5 in the development of BC. The expression of FBXW5 in pan-cancer and breast invasive carcinoma (BRCA) was analyzed using The Cancer Genome Atlas (TCGA) database. FBXW5 level was enhanced in BC tissues. Besides, FBXW5 inhibition significantly decreased cell viability by 49.05% in MDA-MB-231 cells and 62.30% in MCF-7 cells. FBXW5 inhibition significantly inhibited cell proliferation by 66% in MDA-MB-231 cells and 74% in MCF-7 cells. FBXW5 inhibition significantly suppressed cell migration by 77.2% in MDA-MB-231 cells and 82.15% in MCF-7 cells. FBXW5 inhibition significantly inhibited cell invasion by 64.14% in MDA-MB-231 cells and 71.33% in MCF-7 cells. In vivo, FBXW5 depletion reduced tumor weight by 63.39% and tumor volume by 65.17%. Moreover, FBXW5 silencing restrained lung metastases in vivo. Besides, the impact of FBXW5 on the malignant behavior of BC cells was mediated through the regulation of ferroptosis. Mechanically, FBXW5 facilitated Kruppel-like factor 13 (KLF13) degradation by enhancing its ubiquitination. The addition of FBXW5 facilitated cell proliferation, migration, and invasion and inhibited ferroptosis in MDA-MB-231 and MCF-7 cells, which were neutralized by KLF13 overexpression. Besides, the knockdown of KLF13 led to the activation of the PI3K/AKT pathway. KLF13 silencing counteracted the inhibitory effects of FBXW5 depletion on cell proliferation, migration, and invasion, as well as its promotion of ferroptosis, effects that were reversed by LY294002. In conclusion, targeting FBXW5 may serve as a potential therapeutic strategy for BC by modulating the KLF13/PI3K/AKT axis.

TMEM160 inhibits KEAP1 to suppress ferroptosis and induce chemoresistance in gastric cancer

Chemoresistance is the most significant challenge affecting the clinical efficacy of the treatment of patients with gastric cancer (GC). Here we reported that transmembrane protein 160 (TMEM160) suppressed ferroptosis and induced chemoresistance in GC cells. Mechanistically, TMEM160 recruited the E3 ligase TRIM37 to promote K48-linked ubiquitination and degradation of KEAP1, thereby activating NRF2 and transcriptionally upregulating the target genes GPX4 and SLC7A11 to inhibit ferroptosis. Further in vitro and in vivo experiments demonstrated that the combination of TMEM160 targeting and chemotherapy had a synergistic inhibitory effect on the growth of GC cells, which was partially NRF2-dependent. Moreover, TMEM160 and NRF2 protein levels were markedly overexpressed in GC tissues, and their co-overexpression was an independent factor for poor prognosis. Collectively, these findings indicate that TMEM160, as a pivotal negative regulator of ferroptosis, exerts a crucial influence on the chemoresistance of GC through the TRIM37-KEAP1/NRF2 axis, providing a potential new prognostic factor and combination therapy strategy for patients with GC.

Ubiquitin-specific peptidase 49 promotes adenocarcinoma of the esophagogastric junction malignant progression via activating SHCBP1-β-catenin-GPX4 axis

Adenocarcinoma of the esophagogastric junction (AEG) has received widespread attention because of its increasing incidence. However, the molecular mechanism underlying tumor progression remains unclear. Here, we report that the downregulation of ubiquitin-specific peptidase 49 (USP49) promotes ferroptosis in OE33 and OE19 cells, thereby inhibiting cell proliferation in vitro and in vivo, whereas the overexpression of USP49 had the opposite effect. In addition, USP49 downregulation promoted AEG cell radiotherapy sensitivity. Moreover, overexpression of Glutathione PeroXidase 4 reversed the ferroptosis and proliferation inhibition induced by USP49 knockdown. Mechanistically, USP49 deubiquitinates and stabilizes Shc SH2-domain-binding protein 1, subsequently facilitating the entry of β-catenin into the nucleus to enhance Glutathione PeroXidase 4 transcriptional expression. Finally, high USP49 expression was correlated with shorter overall survival in patients with AEG. In summary, our findings identify USP49 as a novel regulator of ferroptosis in AEG cells, indicating that USP49 may be a potential therapeutic target in AEG.

A novel biomarker GATM suppresses proliferation and malignancy of cholangiocarcinoma cells by modulating the JNK/c-Jun signalling pathways

Background

Cholangiocarcinoma (CCA) is the second most common primary malignancy of the liver and is associated with poor prognosis. Despite the emerging role of glycine amidinotransferase (GATM) in cancer development, its function in CCA remains elusive. This study investigated the biological significance and molecular mechanisms of GATM in CCA.

Method

GATM expression was measured using immunohistochemistry and western blotting. Cell proliferation, migration, and invasion were assessed through CCK-8, EdU, clone formation, wound healing, and Transwell assays. Rescue experiments were performed to determine whether the JNK/c-Jun pathway is involved in GATM-mediated CCA development. Immunoprecipitation and mass spectrometry were performed to screen for proteins that interact with GATM. The role of GATM in vivo was investigated according to the xenograft experiment.

Result

GATM expression was downregulated in CCA tissues and cells (p < 0.05) and had a significant suppressive effect on CCA cell proliferation, migration, and invasion in vitro as well as on tumour growth in vivo (p < 0.05); conversely, GATM knockdown promoted these phenotypes (p < 0.05). Notably, GATM inhibited the JNK/c-Jun pathway, and JNK activation abrogated GATM's antitumor effects (p < 0.05). Isocitrate dehydrogenase 1 (IDH1) interacts with GATM, and IDH1 knockdown significantly attenuated GATM protein degradation. Overexpression of IDH1 restored the biological function of CCA by reversing the inhibition of JNK/c-Jun pathway phosphorylation by GATM (p < 0.05).

Conclusion

GATM acts as a tumour suppressor in CCA by regulating the phosphorylation of the JNK/c-Jun pathway. IDH1 interacted with GATM to regulate CCA progression.

Cullin-RING Ligase 4 in Cancer: Structure, Functions, and Mechanisms

Cullin-RING ligase 4 (CRL4) has attracted enormous attentions because of its extensive regulatory roles in a wide variety of biological and pathological events, especially cancer-associated events. CRL4 exerts pleiotropic effects by targeting various substrates for proteasomal degradation or changes in activity through different internal compositions to regulate diverse events in cancer progression. In this review, we summarize the structure of CRL4 with manifold compositional modes and clarify the emerging functions and molecular mechanisms of CRL4 in a series of cancer-associated events.

F-box proteins and gastric cancer: an update from functional and regulatory mechanism to therapeutic clinical prospects

Gastric cancer (GC) is a prevalent malignancy characterized by significant morbidity and mortality, yet its underlying pathogenesis remains elusive. The etiology of GC is multifaceted, involving the activation of oncogenes and the inactivation of antioncogenes. The ubiquitin-proteasome system (UPS), responsible for protein degradation and the regulation of physiological and pathological processes, emerges as a pivotal player in GC development. Specifically, the F-box protein (FBP), an integral component of the SKP1-Cullin1-F-box protein (SCF) E3 ligase complex within the UPS, has garnered attention for its prominent role in carcinogenesis, tumor progression, and drug resistance. Dysregulation of several FBPs has recently been observed in GC, underscoring their significance in disease progression. This comprehensive review aims to elucidate the distinctive characteristics of FBPs involved in GC, encompassing their impact on cell proliferation, apoptosis, invasive metastasis, and chemoresistance. Furthermore, we delve into the emerging role of FBPs as downstream target proteins of non-coding RNAs(ncRNAs) in the regulation of gastric carcinogenesis, outlining the potential utility of FBPs as direct therapeutic targets or advanced therapies for GC.

Individual disruption of 12 testis-enriched genes via the CRISPR/Cas9 system does not affect the fertility of male mice

More than 1200 genes have been shown in the database to be expressed predominantly in the mouse testes. Advances in genome editing technologies such as the CRISPR/Cas9 system have made it possible to create genetically engineered mice more rapidly and efficiently than with conventional methods, which can be utilized to screen genes essential for male fertility by knocking out testis-enriched genes. Finding such genes related to male fertility would not only help us understand the etiology of human infertility but also lead to the development of male contraceptives. In this study, we generated knockout mice for 12 genes (Acrv1, Adgrf3, Atp8b5, Cfap90, Cfap276, Fbxw5, Gm17266, Lrrd1, Mroh7, Nemp1, Spata45, and Trim36) that are expressed predominantly in the testis and examined the appearance and histological morphology of testes, sperm motility, and male fertility. Mating tests revealed that none of these genes is essential for male fertility at least individually. Notably, knockout mice for Gm17266 showed smaller testis size than the wild-type but did not exhibit reduced male fertility. Since 12 genes were not individually essential for male fertilization, it is unlikely that these genes could be the cause of infertility or contraceptive targets. It is better to focus on other essential genes because complementary genes to these 12 genes may exist.

YAP1-CPNE3 positive feedback pathway promotes gastric cancer cell progression

Hippo-Yes-associated protein 1 (YAP1) plays an important role in gastric cancer (GC) progression; however, its regulatory network remains unclear. In this study, we identified Copine III (CPNE3) was identified as a novel direct target gene regulated by the YAP1/TEADs transcription factor complex. The downregulation of CPNE3 inhibited proliferation and invasion, and increased the chemosensitivity of GC cells, whereas the overexpression of CPNE3 had the opposite biological effects. Mechanistically, CPNE3 binds to the YAP1 protein in the cytoplasm, inhibiting YAP1 ubiquitination and degradation mediated by the E3 ubiquitination ligase β-transducin repeat-containing protein (β-TRCP). Thereby activating the transcription of YAP1 downstream target genes, which creates a positive feedback cycle to facilitate GC progression. Immunohistochemical analysis demonstrated significant upregulation of CPNE3 in GC tissues. Survival and Cox regression analyses indicated that high CPNE3 expression was an independent prognostic marker for GC. This study elucidated the pivotal involvement of an aberrantly activated CPNE3/YAP1 positive feedback loop in the malignant progression of GC, thereby uncovering novel prognostic factors and therapeutic targets in GC.

Isoform alterations in the ubiquitination machinery impacting gastrointestinal malignancies

The advancement of RNAseq and isoform-specific expression platforms has led to the understanding that isoform changes can alter molecular signaling to promote tumorigenesis. An active area in cancer research is uncovering the roles of ubiquitination on spliceosome assembly contributing to transcript diversity and expression of alternative isoforms. However, the effects of isoform changes on functionality of ubiquitination machineries (E1, E2, E3, E4, and deubiquitinating (DUB) enzymes) influencing onco- and tumor suppressor protein stabilities is currently understudied. Characterizing these changes could be instrumental in improving cancer outcomes via the identification of novel biomarkers and targetable signaling pathways. In this review, we focus on highlighting reported examples of direct, protein-coded isoform variation of ubiquitination enzymes influencing cancer development and progression in gastrointestinal (GI) malignancies. We have used a semi-automated system for identifying relevant literature and applied established systems for isoform categorization and functional classification to help structure literature findings. The results are a comprehensive snapshot of known isoform changes that are significant to GI cancers, and a framework for readers to use to address isoform variation in their own research. One of the key findings is the potential influence that isoforms of the ubiquitination machinery have on oncoprotein stability.

TMEM160 promotes tumor immune evasion and radiotherapy resistance via PD-L1 binding in colorectal cancer

BACKGROUND

The effectiveness of anti-programmed cell death protein 1(PD-1)/programmed cell death 1 ligand 1(PD-L1) therapy in treating certain types of cancer is associated with the level of PD-L1. However, this relationship has not been observed in colorectal cancer (CRC), and the underlying regulatory mechanism of PD-L1 in CRC remains unclear.

METHODS

Binding of TMEM160 to PD-L1 was determined by co-immunoprecipitation (Co-IP) and GST pull-down assay.The ubiquitination levels of PD-L1 were verified using the ubiquitination assay. Phenotypic experiments were conducted to assess the role of TMEM160 in CRC cells. Animal models were employed to investigate how TMEM160 contributes to tumor growth.The expression and clinical significance of TMEM160 and PD-L1 in CRC tissues were evaluated by immunohistochemistry(IHC).

RESULTS

In our study, we made a discovery that TMEM160 interacts with PD-L1 and plays a role in stabilizing its expression within a CRC model. Furthermore, we demonstrated that TMEM160 hinders the ubiquitination-dependent degradation of PD-L1 by competing with SPOP for binding to PD-L1 in CRC cells. Regarding functionality, the absence of TMEM160 significantly inhibited the proliferation, invasion, metastasis, clonogenicity, and radioresistance of CRC cells, while simultaneously enhancing the cytotoxic effect of CD8 + T cells on tumor cells. Conversely, the upregulation of TMEM160 substantially increased these capabilities. In severely immunodeficient mice, tumor growth derived from lentiviral vector shTMEM160 cells was lower compared with that derived from shNC control cells. Furthermore, the downregulation of TMEM160 significantly restricted tumor growth in immune-competent BALB/c mice. In clinical samples from patients with CRC, we observed a strong positive correlation between TMEM160 expression and PD-L1 expression, as well as a negative correlation with CD8A expression. Importantly, patients with high TMEM160 expression exhibited a worse prognosis compared with those with low or no TMEM160 expression.

CONCLUSIONS

Our study reveals that TMEM160 inhibits the ubiquitination-dependent degradation of PD-L1 that is mediated by SPOP, thereby stabilizing PD-L1 expression to foster the malignant progress, radioresistance, and immune evasion of CRC cells. These findings suggest that TMEM160 holds potential as a target for the treatment of patients with CRC.

Liver transcriptome profiles of dairy cows with different serum metabotypes

In a previously established animal model, 38 multiparous Holstein cows were assigned to 2 groups fed different diets to achieve either a normal (NBCS) or high (HBCS) body condition score (BCS) and backfat thickness (BFT) until dry-off at -49 d before calving (NBCS: BCS <3.5 [3.02 ± 0.24) and BFT <1.2 cm [0.92 ± 0.21]; HBCS: BCS >3.75 [3.82 ± 0.33] and BFT >1.4 cm [2.36 ± 0.35], mean ± SD). The groups were also stratified for comparable milk yields (NBCS: 10,361 ± 302 kg; HBCS: 10,315 ± 437 kg; mean ± SD). The cows were then fed the same diet during the dry period and subsequent lactation, maintaining the differences in BFT and BCS throughout the study. Using the serum metabolomics data, we created a classification model that identified different metabotypes. Machine learning classifiers revealed a distinct cluster labeled HBCS-PN (HBCS predicted normal BCS) among over-conditioned cows. These cows showed higher feed intake and better energy balance than the HBCS-PH (high BCS predicted high BCS) group, while milk yield was similar. The aim of this study was to investigate the changes in the hepatic transcriptome of cows differing in serum-metabotype postpartum. We performed hepatic transcriptome analysis in cows from 3 metabolic clusters: HBCS-PH (n = 8), HBCS-PN (n = 6), and normal BCS predicted normal BCS (NBCS-PN, n = 8) on d 21 (±2) postpartum. Liver tissue from cows expressed a total of 13,118 genes aligned with the bovine genome. A total of 48 differentially expressed genes (DEG; false discovery rate ≤0.1 and fold-change >1.5) were found between NBCS-PN and HBCS-PH cows, whereas 24 DEG (14 downregulated and 10 upregulated) were found between HBCS-PN and HBCS-PH cows. The downregulated DEG (n = 31) in NBCS-PN cows compared with HBCS-PH cows are involved in biosynthetic processes such as lipid, lipoprotein, and cholesterol synthesis (e.g., APOA1, MKX, RPL3L, CANT1, CHPF, FUT1, ZNF696), cell organization, biogenesis, and localization (e.g., SLC12A8, APOA1, BRME1, RPL3L, STAG3, FBXW5, TMEM120A, SLC16A5, FGF21), catabolic processes (e.g., BREH1, MIOX, APOBEC2, FBXW5, NUDT16), and response to external stimuli (e.g., APOA1, FGF21, TMEM120A, FNDC4), whereas upregulated DEG (n = 17) are related to signal transduction and cell motility (e.g., RASSF2, ASPN, SGK1, KIF7, ZEB2, MAOA, ACKR4, TCAF1), suggesting altered metabolic adaptations during lactation. Our results showed 24 DEG between HBCS-PN and HBCS-PH in the liver. The expression of SLC12A8, SLC16A5, FBXW5, OSGIN1, LAMA3, KDELR3, OR4X17, and INHBE, which are responsible for regulating cellular processes was downregulated in HBCS-PN cows compared with HBCS-PH cows. In particular, the downregulation of SLC12A8 and SLC16A5 expression in HBCS-PN cows indicates lower metabolic load and reduced need for NAD+ biosynthesis to support mitochondrial respiratory processes. The upregulation of MAOA, ACKR4, KIF27, SFRP1, and CAV2 in the liver of HBCS-PN cows may indicate adaptive mechanisms to maintain normal liver function in response to increased metabolic demands from over-conditioning. These molecular differences underscore the existence of distinct metabolic types in cows and provide evidence for the role of the liver in shaping different metabolic patterns.

GPR137 inactivates Hippo signaling to promote gastric cancer cell malignancy

As the fifth most common cancer in the world, gastric cancer (GC) ranks as the third major cause of cancer-related death globally. Although surgical resection and chemotherapy still remains the mainstay of potentially curative treatment for GC, chemotherapy resistance and adverse side effects limit their clinical applications. Thus, further investigation of the mechanisms of carcinogenesis in GC and discovery of novel biomarkers is of great concern. We herein report that the elevated expression of GPR137 is correlated with GC. Overexpression of GPR137 potentiates human gastric cancer AGS cell malignancy, including proliferation, migration, invasion, colony formation and xenograft growth in nude mice in vivo, whereas knockout of GPR137 by CRISPR/Cas9 gene editing exerts the opposite effects. Mechanistically, GPR137 could bind to MST, the upstream kinases in Hippo pathway, which disrupts the association of MST with LATS, subsequently activating the transcriptional co-activators, YAP and TAZ, and thereby triggering the target transcription and the alterations in GC cell biological actions consequently. Therefore, our findings may provide with the evidence of developing a potentially novel treatment method with specific target for GC.

Role of F-box proteins in human upper gastrointestinal tumors

Protein ubiquitination and degradation is an essential physiological process in almost all organisms. As the key participants in this process, the E3 ubiquitin ligases have been widely studied and recognized. F-box proteins, a crucial component of E3 ubiquitin ligases that regulates diverse biological functions, including cell differentiation, proliferation, migration, and apoptosis by facilitating the degradation of substrate proteins. Currently, there is an increasing focus on studying the role of F-box proteins in cancer. In this review, we present a comprehensive overview of the significant contributions of F-box proteins to the development of upper gastrointestinal tumors, highlighting their dual roles as both carcinogens and tumor suppressors. We delve into the molecular mechanisms underlying the involvement of F-box proteins in upper gastrointestinal tumors, exploring their interactions with specific substrates and their cross-talks with other key signaling pathways. Furthermore, we discuss the implications of F-box proteins in radiotherapy resistance in the upper gastrointestinal tract, emphasizing their potential as clinical therapeutic and prognostic targets. Overall, this review provides an up-to-date understanding of the intricate involvement of F-box proteins in human upper gastrointestinal tumors, offering valuable insights for the identification of prognostic markers and the development of targeted therapeutic strategies.

DPP2/7 is a Potential Predictor of Prognosis and Target in Immunotherapy in Colorectal Cancer: An Integrative Multi-omics Analysis

BACKGROUND

Colorectal cancer (CRC) ranks among the leading causes of cancerrelated deaths.

OBJECTIVE

This study aimed to illuminate the relationship between DPP7 (also known as DPP2) and CRC through a combination of bioinformatics and experimental methodologies.

METHODS

A multi-dimensional bioinformatic analysis on DPP7 was executed, covering its expression, survival implications, clinical associations, functional roles, immune interactions, and drug sensitivities. Experimental validations involved siRNA-mediated DPP7 knockdown and various cellular assays.

RESULTS

Data from the Cancer Genome Atlas (TCGA) identified high DPP7 expression in solid CRC tumors, with elevated levels adversely affecting patient prognosis. A shift from the N0 to the N2 stage in CRC was associated with increased DPP7 expression. Functional insights indicated the involvement of DPP7 in cancer progression, particularly in extracellular matrix disassembly. Immunological analyses showed its association with immunosuppressive entities, and in vitro experiments in CRC cell lines underscored its oncogenic attributes.

CONCLUSION

DPP7 could serve as a CRC prognosis marker, functioning as an oncogene and representing a potential immunotherapeutic target.

Molecular Insight into Gastric Cancer Invasion-Current Status and Future Directions

Gastric cancer (GC) is one of the most common malignancies worldwide. There has been no efficient therapy for stage IV GC patients due to this disease's heterogeneity and dissemination ability. Despite the rapid advancement of molecular targeted therapies, such as HER2 and immune checkpoint inhibitors, survival of GC patients is still unsatisfactory because the understanding of the mechanism of GC progression is still incomplete. Invasion is the most important feature of GC metastasis, which causes poor mortality in patients. Recently, genomic research has critically deepened our knowledge of which gene products are dysregulated in invasive GC. Furthermore, the study of the interaction of GC cells with the tumor microenvironment has emerged as a principal subject in driving invasion and metastasis. These results are expected to provide a profound knowledge of how biological molecules are implicated in GC development. This review summarizes the advances in our current understanding of the molecular mechanism of GC invasion. We also highlight the future directions of the invasion therapeutics of GC. Compared to conventional therapy using protease or molecular inhibitors alone, multi-therapy targeting invasion plasticity may seem to be an assuring direction for the progression of novel strategies.

KMT2A maintains stemness of gastric cancer cells through regulating Wnt/β-catenin signaling-activated transcriptional factor KLF11

The molecular mechanisms of epigenetic regulation in gastric cancer development are not yet well established. In this study, we demonstrated that KMT2A was highly expressed in gastric cancer and associated with poor outcomes of patients and revealed that KMT2A was significantly associated with stemness and increased nuclear β-catenin in gastric cancer. Mechanistically, KMT2A activated the translocation of β-catenin into the nucleus of gastric cancer cells, and then, β-catenin served as a coactivator of KLF11, which promoted the expression of specific gastric cancer stemness-related molecules, including SOX2 and FOXM1. Together, KMT2A is an important epigenetic regulator of gastric cancer stemness, which provides a novel insight to the potential application of targeting against KMT2A in treating gastric cancer.

Function, mechanism and drug discovery of ubiquitin and ubiquitin-like modification with multiomics profiling for cancer therapy

Ubiquitin (Ub) and ubiquitin-like (Ubl) pathways are critical post-translational modifications that determine whether functional proteins are degraded or activated/inactivated. To date, >600 associated enzymes have been reported that comprise a hierarchical task network (e.g., E1-E2-E3 cascade enzymatic reaction and deubiquitination) to modulate substrates, including enormous oncoproteins and tumor-suppressive proteins. Several strategies, such as classical biochemical approaches, multiomics, and clinical sample analysis, were combined to elucidate the functional relations between these enzymes and tumors. In this regard, the fundamental advances and follow-on drug discoveries have been crucial in providing vital information concerning contemporary translational efforts to tailor individualized treatment by targeting Ub and Ubl pathways. Correspondingly, emphasizing the current progress of Ub-related pathways as therapeutic targets in cancer is deemed essential. In the present review, we summarize and discuss the functions, clinical significance, and regulatory mechanisms of Ub and Ubl pathways in tumorigenesis as well as the current progress of small-molecular drug discovery. In particular, multiomics analyses were integrated to delineate the complexity of Ub and Ubl modifications for cancer therapy. The present review will provide a focused and up-to-date overview for the researchers to pursue further studies regarding the Ub and Ubl pathways targeted anticancer strategies.

Ubiquitination network in the type I IFN-induced antiviral signaling pathway

Type I IFN (IFN-I) is the body's first line of defense against pathogen infection. IFN-I can induce cellular antiviral responses and therefore plays a key role in driving antiviral innate and adaptive immunity. Canonical IFN-I signaling activates the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway, which induces the expression of IFN-stimulated genes and eventually establishes a complex antiviral state in the cells. Ubiquitin is a ubiquitous cellular molecule for protein modifications, and the ubiquitination modifications of protein have been recognized as one of the key modifications that regulate protein levels and/or signaling activation. Despite great advances in understanding the ubiquitination regulation of many signaling pathways, the mechanisms by which protein ubiquitination regulates IFN-I-induced antiviral signaling have not been explored until very recently. This review details the current understanding of the regulatory network of ubiquitination that critically controls the IFN-I-induced antiviral signaling pathway from three main levels, including IFN-I receptors, IFN-I-induced cascade signals, and effector IFN-stimulated genes.

Targeting XPO6 inhibits prostate cancer progression and enhances the suppressive efficacy of docetaxel

BACKGROUND

Although XPO6, one of the Exportin family members, functions in malignant progression of certain types of cancer, its role in prostate cancer (PCa) has not been elucidated. Herein, we investigated the oncogenic effect and clarified the downstream mechanism of XPO6 in PCa cells.

METHODS

We detected the expression level of XPO6 in PCa tissues by immunohistochemistry (IHC) and analyzed the correlation between clinicopathological characteristics and XPO6 level based on TCGA database. The effects of XPO6 in the proliferation and migration or resistance to docetaxel (DTX) in PCa cells were assessed using CCK8, colony formation, wound-healing and Transwell assays. Mice experiments were performed to investigate the role of XPO6 in tumor progression and DTX effect in vivo. Further, functional analysis of DEGs revealed the correlation of XPO6 with Hippo pathway and XPO6 could promote the expression and nuclear translocation of YAP1 protein. Furthermore, blocking Hippo pathway with YAP1 inhibitor leads to the loss of XPO6-mediated regulation of biological functions.

RESULTS

XPO6 was highly expressed and positively correlated with the clinicopathological characteristics of PCa. Functional experiments indicated that XPO6 could promote tumor development and DTX resistance in PCa. Mechanistically, we further confirmed that XPO6 could regulate Hippo pathway via mediating YAP1 protein expression and nuclear translocation thereby promoting PCa progression and chemotherapeutic resistance.

CONCLUSION

In conclusion, our research reveals that XPO6 potentially function as an oncogene and promotes DTX resistance of PCa, suggesting that XPO6 could be both a potential prognostic marker as well as a therapeutic target to effectively overcome DTX resistance.

UPS: Opportunities and challenges for gastric cancer treatment

Gastric cancer remains the fourth most frequently diagnosed malignancy and the fifth leading cause of cancer-related mortality worldwide owning to the lack of efficient drugs and targets for therapy. Accumulating evidence indicates that UPS, which consists of E1, E2, and E3 enzymes and proteasome, plays an important role in the GC tumorigenesis. The imbalance of UPS impairs the protein homeostasis network during development of GC. Therefore, modulating these enzymes and proteasome may be a promising strategy for GC target therapy. Besides, PROTAC, a strategy using UPS to degrade the target protein, is an emerging tool for drug development. Thus far, more and more PROTAC drugs enter clinical trials for cancer therapy. Here, we will analyze the abnormal expression enzymes in UPS and summarize the E3 enzymes which can be developed in PROTAC so that it can contribute to the development of UPS modulator and PROTAC technology for GC therapy.

The Hippo signaling pathway in gastric cancer

Gastric cancer (GC) is an aggressive malignant disease which still lacks effective early diagnosis markers and targeted therapies, representing the fourth-leading cause of cancer-associated death worldwide. The Hippo signaling pathway plays crucial roles in organ size control and tissue homeostasis under physiological conditions, yet its aberrations have been closely associated with several hallmarks of cancer. The last decade witnessed a burst of investigations dissecting how Hippo dysregulation contributes to tumorigenesis, highlighting the therapeutic potential of targeting this pathway for tumor intervention. In this review, we systemically document studies on the Hippo pathway in the contexts of gastric tumor initiation, progression, metastasis, acquired drug resistance, and the emerging development of Hippo-targeting strategies. By summarizing major open questions in this field, we aim to inspire further in-depth understanding of Hippo signaling in GC development, as well as the translational implications of targeting Hippo for GC treatment.

Vestigial-like 1 (VGLL1): An ancient co-transcriptional activator linking wing, placenta, and tumor development

Vestigial-like 1 (VGLL1) is a recently discovered driver of proliferation and invasion that is expressed in many aggressive human malignancies and is strongly associated with poor prognosis. The VGLL1 gene encodes for a co-transcriptional activator that shows intriguing structural similarity to key activators in the hippo pathway, providing important clues to its functional role. VGLL1 binds to TEADs in an analogous fashion to YAP1 but appears to activate a distinct set of downstream gene targets. In mammals, VGLL1 expression is found almost exclusively in placental trophoblasts, cells that share many hallmarks of cancer. Due to its role as a driver of tumor progression, VGLL1 has become a target of interest for potential anticancer therapies. In this review, we discuss VGLL1 from an evolutionary perspective, contrast its role in placental and tumor development, summarize the current knowledge of how signaling pathways can modulate VGLL1 function, and discuss potential approaches for targeting VGLL1 therapeutically.

Upregulated GPRC5A disrupting the Hippo pathway promotes the proliferation and migration of pancreatic cancer cells via the cAMP-CREB axis

BACKGROUND

Pancreatic cancer has a high mortality rate worldwide, and is predicted to be third leading cause of death in the near future. However, the regulatory mechanisms that inhibit the progression of pancreatic cancer remain elusive. Currently, exploring the function and mechanisms of GPCRs (G-protein coupled receptors) is an important way to discover promising therapeutic targets for cancer.

METHODS

GPRC5A expression was measured using real-time quantitative PCR, immunohistochemistry and western blot assays. Cell proliferation and migration were assessed using CCK-8, clone formation, wound-healing and transwell assays. A cytosolic/nuclear distribution experiment was used to detect the protein location transfer. A xenograft model of pancreatic cancer was established to explore the role of GPRC5A in vivo.

RESULTS

GPRC5A expression was increased in pancreatic cancer, and disruption of GPRC5A expression inhibited tumor growth in vivo. Mechanistically, GPRC5A positively regulated the transcription of YAP1 through cAMP-CREB signaling. Moreover, we show that the proliferation and migration induced by GPRC5A in pancreatic cancer could be rescued by inhibiting YAP1 expression.

CONCLUSIONS

GPRC5A interacts with the Hippo pathway to promote the progression of pancreatic cancer. These findings reveal an important crosstalk model and provide potential targets for pancreatic cancer therapy.

Pan-cancer analysis of FBXW family with potential implications in prognosis and immune infiltration

Background

The F-box and WD repeat domain containing (FBXW) family of SCF E3 complexes has 10 members that are responsible for ubiquitination and degradation of substrate proteins involved in cell cycle regulation and tumorigenesis. Among them, FBXW1 (also called b-TrCP1/BTRC) and FBXW7 are the central proteins in this category. However, there is still a lack of elaborate exploration of the contribution of FBXW family members, especially FBXW1 and FBXW7, in various tumor types.

Methods

In this present study, we preliminarily analyzed the genetic structure characteristics of the FBXW family, and systematically investigated their expression patterns and clinical correlations based on the TCGA pan-cancer data. Survival analysis of FBXWs was also conducted through the Kaplan-Meier method. In addition, we assessed their immune infiltration level through immune-related algorithms like Timer and xCell.

Results

There were obvious genetic heterogeneity and different clinical traits in FBXW family members. Moreover, we found that FBXW family genes may be useful in predicting prognosis and therapeutic efficacy using survival analysis. In addition, the immune infiltration of FBXW family was also clearly illustrated in this study. The results showed these genes were closely involved in immune components such as immune score, immune subtypes, tumor-infiltrating lymphocytes and immune checkpoints. Notedly, FBXW1 as an oncogene and FBXW7 as a tumor suppressor gene also show opposite relationships on immune cells.

Conclusion

Our results provided valuable strategies to guide the therapeutic orientation concerning the role of FBXW family genes in cancer.

Targeting the Hippo Pathway in Gastric Cancer and Other Malignancies in the Digestive System: From Bench to Bedside

The Hippo pathway is an evolutionally conserved signaling cascade that controls organ size and tissue regeneration under physiological conditions, and its aberrations have been well studied to promote tumor initiation and progression. Dysregulation of the Hippo tumor suppressor signaling frequently occurs in gastric cancer (GC) and other solid tumors and contributes to cancer development through modulating multiple aspects, including cell proliferation, survival, metastasis, and oncotherapy resistance. In the clinic, Hippo components also possess diagnostic and prognostic values for cancer patients. Considering its crucial role in driving tumorigenesis, targeting the Hippo pathway may greatly benefit developing novel cancer therapies. This review summarizes the current research progress regarding the core components and regulation of the Hippo pathway, as well as the mechanism and functional roles of their dysregulation in gastrointestinal malignancies, especially in GC, and discusses the therapeutic potential of targeting the Hippo pathway against cancers.