VCP/p97 targets the nuclear export and degradation of p27Kip1 during G1 to S phase transition

p37 regulates VCP/p97 shuttling and functions in the nucleus and cytosol

The AAA+-ATPase valosin-containing protein (VCP; also called p97 or Cdc48), a major protein unfolding machinery with a variety of essential functions, localizes to different subcellular compartments where it has different functions. However, the processes regulating the distribution of VCP between the cytosol and nucleus are not understood. Here, we identified p37 (also called UBXN2B) as a major factor regulating VCP nucleocytoplasmic shuttling. p37-dependent VCP localization was crucial for local cytosolic VCP functions, such as autophagy, and nuclear functions in DNA damage repair. Mutations in VCP causing multisystem proteinopathy enhanced its association with p37, leading to decreased nuclear localization of VCP, which enhanced susceptibility to DNA damage accumulation. Both VCP localization and DNA damage susceptibility in cells with such mutations were normalized by lowering p37 levels. Thus, we uncovered a mechanism by which VCP nucleocytoplasmic distribution is fine-tuned, providing a means for VCP to respond appropriately to local needs.

CDC48 in plants and its emerging function in plant immunity

Protein homeostasis, namely the balance between protein synthesis and degradation, must be finely controlled to ensure cell survival, notably through the ubiquitin-proteasome system (UPS). In all species, including plants, homeostasis is disrupted by biotic and abiotic stresses. A key player in the maintenance of protein balance, the protein CDC48, shows emerging functions in plants, particularly in response to biotic stress. In this review on CDC48 in plants, we detail its highly conserved structure, describe a gene expansion that is only present in Viridiplantae, discuss its various functions and regulations, and finally highlight its recruitment, still not clear, during the plant immune response.

Proteomics analysis of serum and urine identifies VCP and CTSA as potential biomarkers associated with multiple myeloma

AIMS

We analyzed the differentially expressed proteins (DEPs) in serum and urine in order to provide new potential biomarkers for MM.

METHODS

Data-Independent Acquisition-based proteomics of serum and urine was performed to identify potential biomarkers for MM patients. Then we performed Western Blotting (WB), ELISA along with their ROC curve analysis to confirm DEPs.

RESULTS

A total of 1653 proteins in serum and 4519 proteins in urine were identified using Data-Dependent Acquisition method. VCP was the only protein that showed significant differences in different comparison groups in both serum and urine. Pathway analysis revealed that protein processing in the endoplasmic reticulum was the most relevant pathway associated with MM. Furthermore, the increased expression of HSP90B1, VCP, CTSA, HYOU1, PDIA4, and RAB7A was detected by WB. The results of ELISA indicated that a combination of VCP and CTSA provided a high area under curve (AUC) value of 0.883 (95 % CI, 0.769-0.997, p < 0.001) to diagnose NDMM. The combination of VCP, CTSA, ALB, and HGB exhibited better performance (AUC = 0.981), with 100 % specificity and 86.7 % sensitivity.

CONCLUSION

These findings suggest VCP and CTSA exhibit potential as biomarkers for MM, which may be helpful in the molecular mechanisms and pathogenesis upon further investigation.

Nuclear VCP drives colorectal cancer progression by promoting fatty acid oxidation

Fatty acid oxidation (FAO) fuels many cancers. However, knowledge of pathways that drive FAO in cancer remains unclear. Here, we revealed that valosin-containing protein (VCP) upregulates FAO to promote colorectal cancer growth. Mechanistically, nuclear VCP binds to histone deacetylase 1 (HDAC1) and facilitates its degradation, thus promoting the transcription of FAO genes, including the rate-limiting enzyme carnitine palmitoyltransferase 1A (CPT1A). FAO is an alternative fuel for cancer cells in environments exhibiting limited glucose availability. We observed that a VCP inhibitor blocked the upregulation of FAO activity and CPT1A expression triggered by metformin in colorectal cancer (CRC) cells. Combined VCP inhibitor and metformin prove more effective than either agent alone in culture and in vivo. Our study illustrates the molecular mechanism underlying the regulation of FAO by nuclear VCP and demonstrates the potential therapeutic utility of VCP inhibitor and metformin combination treatment for colorectal cancer.

Inhibition of VCP modulates NF-κB signaling pathway to suppress multiple myeloma cell proliferation and osteoclast differentiation

Multiple myeloma (MM) is the second most common hematological malignancy, in which the dysfunction of the ubiquitin-proteasome pathway is associated with the pathogenesis. The valosin containing protein (VCP)/p97, a member of the AAA+ ATPase family, possesses multiple functions to regulate the protein quality control including ubiquitin-proteasome system and molecular chaperone. VCP is involved in the occurrence and development of various tumors while still elusive in MM. VCP inhibitors have gradually shown great potential for cancer treatment. This study aims to identify if VCP is a therapeutic target in MM and confirm the effect of a novel inhibitor of VCP (VCP20) on MM. We found that VCP was elevated in MM patients and correlated with shorter survival in clinical TT2 cohort. Silencing VCP using siRNA resulted in decreased MM cell proliferation via NF-κB signaling pathway. VCP20 evidently inhibited MM cell proliferation and osteoclast differentiation. Moreover, exosomes containing VCP derived from MM cells partially alleviated the inhibitory effect of VCP20 on cell proliferation and osteoclast differentiation. Mechanism study revealed that VCP20 inactivated the NF-κB signaling pathway by inhibiting ubiquitination degradation of IκBα. Furthermore, VCP20 suppressed MM cell proliferation, prolonged the survival of MM model mice and improved bone destruction in vivo. Collectively, our findings suggest that VCP is a novel target in MM progression. Targeting VCP with VCP20 suppresses malignancy progression of MM via inhibition of NF-κB signaling pathway.

Valosin containing protein (VCP): initiator, modifier, and potential drug target for neurodegenerative diseases

The AAA+ ATPase valosin containing protein (VCP) is essential for cell and organ homeostasis, especially in cells of the nervous system. As part of a large network, VCP collaborates with many cofactors to ensure proteostasis under normal, stress, and disease conditions. A large number of mutations have revealed the importance of VCP for human health. In particular, VCP facilitates the dismantling of protein aggregates and the removal of dysfunctional organelles. These are critical events to prevent malfunction of the brain and other parts of the nervous system. In line with this idea, VCP mutants are linked to the onset and progression of neurodegeneration and other diseases. The intricate molecular mechanisms that connect VCP mutations to distinct brain pathologies continue to be uncovered. Emerging evidence supports the model that VCP controls cellular functions on multiple levels and in a cell type specific fashion. Accordingly, VCP mutants derail cellular homeostasis through several mechanisms that can instigate disease. Our review focuses on the association between VCP malfunction and neurodegeneration. We discuss the latest insights in the field, emphasize open questions, and speculate on the potential of VCP as a drug target for some of the most devastating forms of neurodegeneration.

Expression and significance of cyclin D1, cyclin-dependent kinase 4 and cyclin-dependent kinase inhibitor P27 in patients with non-neoplastic epithelial disorders of the vulva

Non-neoplastic epithelial disorders of the vulva (NNEDV) are prevalent and refractory gynecological diseases. However, the underlying pathogenesis of these diseases remain unclear. The present study aimed to investigate the expression and significance of cyclin D1, cyclin-dependent kinase 4 (CDK4) and cyclin-dependent kinase inhibitor P27 (P27) in patients with NNEDV and provide a reference for clinical diagnosis and treatment. Normal vulvar skin samples from patients with perineum repair (control group, n=20) and skin samples from the vulvar lesions of patients with NNEDV (NNEDV group, n=36) were collected. Expression levels of cyclin D1, CDK4 and P27 were assessed in the samples using immunohistochemistry. The expression of each protein was evaluated based on the mean optical density (MOD). The MODs of cyclin D1 and CDK4 were significantly higher in samples of the three pathological types of NNEDV, namely squamous hyperplasia (SH), lichen sclerosus (LS) and mixed SH and LS lesions, compared with those of the control group. The MOD of P27 was lower in samples of the three pathological types of NNEDV than in the control group, although the difference was not statistically significant. No significant differences in the MOD of cyclin D1, CDK4 and P27 were detected among the three pathological types of NNEDV. The ratios of the MOD of cyclin D1 and CDK4 in the prickle cell layer to those in the basal cell layer were significantly higher in the NNEDV group than in the control group. However, the ratio of the MOD of P27 in the prickle cell layer to that in the basal cell layer exhibited no significant difference between the NNEDV and control groups. NNEDV has the potential for malignant transformation. The occurrence and development of NNEDV may be associated with the acceleration of cell proliferation, in which cyclin D1, CDK4 and P27 contribute to regulation of the cell cycle. Therefore, cyclin D1, CDK4 and P27 may be potential targets in the development of new clinical therapeutic drugs for patients with NNEDV.

Novel VCP activator reverses multisystem proteinopathy nuclear proteostasis defects and enhances TDP-43 aggregate clearance

Pathogenic variants in VCP cause multisystem proteinopathy (MSP), a disease characterized by multiple clinical phenotypes including inclusion body myopathy, Paget's disease of the bone, and frontotemporal dementia (FTD). How such diverse phenotypes are driven by pathogenic VCP variants is not known. We found that these diseases exhibit a common pathologic feature, ubiquitinated intranuclear inclusions affecting myocytes, osteoclasts and neurons. Moreover, knock-in cell lines harboring MSP variants show a reduction in nuclear VCP. Given that MSP is associated with neuronal intranuclear inclusions comprised of TDP-43 protein, we developed a cellular model whereby proteostatic stress results in the formation of insoluble intranuclear TDP-43 aggregates. Consistent with a loss of nuclear VCP function, cells harboring MSP variants or cells treated with VCP inhibitor exhibited decreased clearance of insoluble intranuclear TDP-43 aggregates. Moreover, we identified four novel compounds that activate VCP primarily by increasing D2 ATPase activity whereby pharmacologic VCP activation appears to enhance clearance of insoluble intranuclear TDP-43 aggregate. Our findings suggest that VCP function is important for nuclear protein homeostasis, that MSP may be the result of impaired nuclear proteostasis, and that VCP activation may be potential therapeutic by virtue of enhancing the clearance of intranuclear protein aggregates.

Knockdown of UBE2I inhibits tumorigenesis and enhances chemosensitivity of cholangiocarcinoma via modulating p27kip1 nuclear export

The asymptomatic nature of cholangiocarcinoma (CCA), particularly during its early stages, in combination with its high aggressiveness and chemoresistance, significantly compromises the efficacy of current therapeutic options, contributing to a dismal prognosis. As a tumor suppressor that inhibits the cell cycle, abnormal cytoplasmic p27kip1 localization is related to chemotherapy resistance and often occurs in various cancers, including CCA. Nevertheless, the underlying mechanism is unclear. SUMOylation, which is involved in regulating subcellular localization and the cell cycle, is a posttranslational modification that regulates p27kip1 activity. Here, we confirmed that UBE2I, as the only key enzyme for SUMOylation, was highly expressed and p27kip1 was downregulated in CCA tissues, which were associated with poor outcomes in CCA. Moreover, UBE2I silencing inhibited CCA cell proliferation, delayed xenograft tumor growth in vivo, and sensitized CCA cells to the chemotherapeutics, which may be due to cell cycle arrest induced by p27kip1 nuclear accumulation. According to the immunoprecipitation result, we found that UBE2I could bind p27kip1, and the binding amount of p27kip1 and SUMO-1 decreased after UBE2I silencing. Moreover, nuclear retention of p27kip1 was induced by UBE2I knockdown and SUMOylation or CRM1 inhibition, further suggesting that UBE2I could cooperate with CRM1 in the nuclear export of p27kip1. These data indicate that UBE2I-mediated SUMOylation is a novel regulatory mechanism that underlies p27kip1 export and controls CCA tumorigenesis, providing a therapeutic option for CCA treatment.

Downregulation of SMIM3 inhibits growth of leukemia via PI3K-AKT signaling pathway and correlates with prognosis of adult acute myeloid leukemia with normal karyotype

BACKGROUND

Acute myeloid leukemia (AML) patients with normal karyotype (NK-AML) have significant variabilities in outcomes. The European Leukemia Net stratification system and some prognostic models have been used to evaluate risk stratification. However, these common standards still have some limitations. The biological functions and mechanisms of Small Integral Membrane Protein 3 (SMIM3) have seldomly been investigated. To this date, the prognostic value of SMIM3 in AML has not been reported. This study aimed to explore the clinical significance, biological effects and molecular mechanisms of SMIM3 in AML.

METHODS

RT-qPCR was applied to detect the expression level of SMIM3 in bone marrow specimens from 236 newly diagnosed adult AML patients and 23 healthy volunteers. AML cell lines, Kasumi-1 and THP-1, were used for lentiviral transfection. CCK8 and colony formation assays were used to detect cell proliferation. Cell cycle and apoptosis were analyzed by flow cytometry. Western blot was performed to explore relevant signaling pathways. The biological functions of SMIM3 in vivo were validated by xenograft tumor mouse model. Survival rate was evaluated by Log-Rank test and Kaplan-Meier. Cox regression model was used to analyze multivariate analysis. The correlations between SMIM3 and drug resistance were also explored.

RESULTS

Through multiple datasets and our clinical group, SMIM3 was shown to be significantly upregulated in adult AML compared to healthy subjects. SMIM3 overexpression conferred a worse prognosis and was identified as an independent prognostic factor in 95 adult NK-AML patients. Knockdown of SMIM3 inhibited cell proliferation and cell cycle progression, and induced cell apoptosis in AML cells. The reduced SMIM3 expression significantly suppressed tumor growth in the xenograft mouse model. Western blot analysis showed downregulation of p-PI3K and p-AKT in SMIM3-knockdown AML cell lines. SMIM3 may also be associated with some PI3K-AKT and first-line targeted drugs.

CONCLUSIONS

SMIM3 was highly expressed in adult AML, and such high-level expression of SMIM3 was associated with a poor prognosis in adult AML. Knockdown of SMIM3 inhibited the proliferation of AML through regulation of the PI3K-AKT signaling pathway. SMIM3 may serve as a potential prognostic marker and a therapeutic target for AML in the future.

The phosphorylation and dephosphorylation switch of VCP/p97 regulates the architecture of centrosome and spindle

The proper orientation of centrosome and spindle is essential for genome stability; however, the mechanism that governs these processes remains elusive. Here, we demonstrated that polo-like kinase 1 (Plk1), a key mitotic kinase, phosphorylates residue Thr76 in VCP/p97 (an AAA-ATPase), at the centrosome from prophase to anaphase. This phosphorylation process recruits VCP to the centrosome and in this way, it regulates centrosome orientation. VCP exhibits strong co-localization with Eg5 (a mitotic kinesin motor), at the mitotic spindle, and the dephosphorylation of Thr76 in VCP is required for the enrichment of both VCP and Eg5 at the spindle, thus ensuring proper spindle architecture and chromosome segregation. We also showed that the phosphatase, PTEN, is responsible for the dephosphorylation of Thr76 in VCP; when PTEN was knocked down, the normal spread of VCP from the centrosome to the spindle was abolished. Cryo-EM structures of VCPT76A and VCPT76E, which represent dephosphorylated and phosphorylated states of VCP, respectively, revealed that the Thr76 phosphorylation modulates VCP by altering the inter-domain and inter-subunit interactions, and ultimately the nucleotide-binding pocket conformation. Interestingly, the tumor growth in nude mice implanted with VCPT76A-reconstituted cancer cells was significantly slower when compared with those implanted with VCPWT-reconstituted cancer cells. Collectively, our findings demonstrate that the phosphorylation and dephosphorylation switch of VCP regulates the architecture of centrosome and spindle for faithful chromosome segregation.

An Integrated In Silico, In Vitro and Tumor Tissues Study Identified Selenoprotein S (SELENOS) and Valosin-Containing Protein (VCP/p97) as Novel Potential Associated Prognostic Biomarkers in Triple Negative Breast Cancer

Simple Summary

Triple negative breast cancer (TNBC) represents a clinical challenge because its early relapse, poor overall survival and lack of effective treatments. Altered levels selenoproteins have been correlated with development and progression of some cancers, however, no consistent data are available about their involvement in TNBC. Here we analyzed the expression profile of all twenty-five human selenoproteins in TNBC cells and tissues by a systematic approach, integrating in silico and wet lab approaches. We showed that the expression profiles of five selenoproteins are specifically dysregulated in TNBC. Most importantly, by a bioinformatics analysis, we selected selenoprotein S and its interacting protein valosin-containing protein (VCP/p97) as inter-related with the others and whose coordinated over-expression is associated with poor prognosis in TNBC. Overall, we highlighted two mechanistically related novel proteins whose correlated expression could be exploited for a better definition of prognosis as well as suggested as novel therapeutic target in TNBC.

Abstract

Background. Triple negative breast cancer (TNBC) is a heterogeneous group of tumors with early relapse, poor overall survival, and lack of effective treatments. Hence, new prognostic biomarkers and therapeutic targets are needed. Methods. The expression profile of all twenty-five human selenoproteins was analyzed in TNBC by a systematic approach.In silicoanalysis was performed on publicly available mRNA expression datasets (Cancer Cell Line Encyclopedia, CCLE and Library of Integrated Network-based Cellular Signatures, LINCS). Reverse transcription quantitative PCR analysis evaluated selenoprotein mRNA expression in TNBC versus non-TNBC and normal breast cells, and in TNBC tissues versus normal counterparts. Immunohistochemistry was employed to study selenoproteins in TNBC tissues. STRING and Cytoscape tools were used for functional and network analysis. Results.GPX1, GPX4, SELENOS, TXNRD1 and TXNRD3 were specifically overexpressed in TNBC cells, tissues and CCLE/LINCS datasets. Network analysis demonstrated that SELENOS-binding valosin-containing protein (VCP/p97) played a critical hub role in the TNBCselenoproteins sub-network, being directly associated with SELENOS expression. The combined overexpression of SELENOS and VCP/p97 correlated with advanced stages and poor prognosis in TNBC tissues and the TCGA dataset. Conclusion. Combined evaluation of SELENOS and VCP/p97 might represent a novel potential prognostic signature and a therapeutic target to be exploited in TNBC.

Valosin-Containing Protein (VCP)/p97: A Prognostic Biomarker and Therapeutic Target in Cancer

Valosin-containing protein (VCP)/p97, a member of the AAA+ ATPase family, is a molecular chaperone recruited to the endoplasmic reticulum (ER) membrane by binding to membrane adapters (nuclear protein localization protein 4 (NPL4), p47 and ubiquitin regulatory X (UBX) domain-containing protein 1 (UBXD1)), where it is involved in ER-associated protein degradation (ERAD). However, VCP/p97 interacts with many cofactors to participate in different cellular processes that are critical for cancer cell survival and aggressiveness. Indeed, VCP/p97 is reported to be overexpressed in many cancer types and is considered a potential cancer biomarker and therapeutic target. This review summarizes the role of VCP/p97 in different cancers and the advances in the discovery of small-molecule inhibitors with therapeutic potential, focusing on the challenges associated with cancer-related VCP mutations in the mechanisms of resistance to inhibitors.

Disruption of p97/VCP induces autophagosome accumulation, cell cycle arrest and apoptosis in human choriocarcinoma cells

Gestational choriocarcinoma is aggressive trophoblastic disease. The development, progression and the cure of this disease is not well-established. p97/Valosin containing protein has been shown to play critical roles in many cellular processes. In various cancers, higher expression of p97/VCP has been reported and targeting of p97/VCP with its spesific inhibitors or siRNA's (siVCP) in cancer therapy was suggested. However, no study is avaible about the expression and function of p97/VCP in gestational choriocarcinoma. Hence, the aim of the study was to evaluate effects of p97/VCP inhibitor, DBeQ and siVCP on choriocarcinoma cells. We use human placental choriocarcinoma cell line (Jeg3) as model to find out the effects of DBeQ and VCP siRNA's (siVCP) on apoptotic and autophagic pathway by immunflouroscence staining, Western blotting, qPCR and flow-cytometry. p97/VCP siRNA's and DBeQ induced accumulation of autophagic proteins, LC3II and p62 in the cytoplasm of Jeg3 cells detected. Concurrently, Jeg3 cells treated with DBeQ and siVCP demonstrated G0/G1 cell cycle arrest, accompanied by accumulation of poly-ubiquitinated proteins. Moreover, disruption of p97/VCP by siRNA and DBeQ inhibited cancer cell growth managing the caspases-3 and -7. Our results show that inhibition of p97/VCP activity with DBeQ and depletion of p97/VCP expression with siRNA in Jeg3 cells induce caspase activation, inhibits cell proliferation and leads to a defect in autophagosome maturation, thus providing potential target for the prevention and treatment of choriocarcinoma.