TRIP13 modulates protein deubiquitination and accelerates tumor development and progression of B cell malignancies

Bardoxolone displays potent activity against triple negative breast cancer by inhibiting the TRIP13/STAT3 circuit

Triple negative breast cancer (TNBC) is difficult to treat and novel therapeutic targets remain to be identified. TRIP13, an AAA+ ATPase, is highly expressed in breast cancer and predicts poor prognosis; however, the specific mechanism is not fully understood. In the present study, we found TRIP13 promotes TNBC cell viability and migration. In a mechanistic study, TRIP13 is found to activate STAT3 but not other STAT members. Out of expectation, TRIP13 is found to be upregulated by STAT3 and STAT3 specifically recognizes and binds to the STAT3-recognition element in the regulatory region of TRIP13. Moreover, we found bardoxolone, a recently approved drug for the treatment of chronic kidney disease, displays potent activity by inhibiting STAT3 activation and downregulating TRIP13. Furthermore, bardoxolone inhibits breast cancer cell proliferation and migration, and induces apoptosis. Consistent with this finding, ectopic expression of TRIP13 ablates bardoxolone-induced breast cancer cell apoptosis. Bardoxolone also exerts great activity to suppress TNBC tumor growth in vivo but does not show toxicity. Therefore, we reveal that the TRIP13/STAT3 circuit promotes TNBC cell proliferation and this circuit is a promising target for the treatment of TNBC.

Post-Translational Modifications in Multiple Myeloma: Mechanisms of Drug Resistance and Therapeutic Opportunities

Multiple myeloma (MM) remains an incurable hematologic malignancy due to the inevitable development of drug resistance, particularly in relapsed or refractory cases. Post-translational modifications (PTMs), including phosphorylation, ubiquitination, acetylation, and glycosylation, play pivotal roles in regulating protein function, stability, and interactions, thereby influencing MM pathogenesis and therapeutic resistance. This review comprehensively explores the mechanisms by which dysregulated PTMs contribute to drug resistance in MM, focusing on their impact on key signaling pathways, metabolic reprogramming, and the tumor microenvironment. We highlight how PTMs modulate drug uptake, alter drug targets, and regulate cell survival signals, ultimately promoting resistance to PIs, IMiDs, and other therapeutic agents. Furthermore, we discuss emerging therapeutic strategies targeting PTM-related pathways, which offer promising avenues for overcoming resistance to treatment. By integrating preclinical and clinical insights, this review underscores the potential of PTM-targeted therapies to enhance treatment efficacy and improve patient outcomes in MM.

PDCD11 Stabilizes C-MYC Oncoprotein by Hindering C-MYC-SKP2 Negative Feedback Loop to Facilitate Progression of p53-Mutant Breast and Colon Malignancies

C-MYC is a proto-oncoprotein whose dysregulation triggers tumorigenesis and tumor progression in ≈70% of cancer cases. It is presently demonstrated that aberrantly upregulated MYC is caused by the overexpressed and "extra-nucleolar" PDCD11 in p53-mutant breast and colon cancer cells, which is highly correlated to tumor progression, metastasis, and recurrence. In the nucleoplasm, PDCD11 binds to the TAD of C-MYC to prevent SKP2, a transcriptional target of C-MYC as well as one of the major E3 ligase components targeting C-MYC, from interacting with and ubiquitinating C-MYC in feedback. The ensuing stabilized C-MYC activates downstream signaling to facilitate the cellular G1/S transition, proliferation, and migration. PDCD11 silencing restores SKP2-mediated C-MYC degradation, thereby remarkably suppressing tumor growth and metastasis in nude mice. These findings highlight PDCD11 as a novel C-MYC partner and thereby offer a potential therapeutic rationale to challenge PDCD11-mediated "pro-stabilization" effect on C-MYC, a widely considered "undruggable" target, to combat C-MYC-driven malignancies with p53 mutation.

Exosome-transmitted HSPA9 facilitates bortezomib resistance by targeting TRIP13/USP1 signaling in multiple myeloma

BACKGROUND

Resistance to the proteasome inhibitor bortezomib (BTZ) poses a formidable therapeutic challenge in multiple myeloma (MM). Our study aims to analyze the mechanism by which exosomes heat shock 70 kDa protein 9 (HSPA9) secreted by BTZ-resistant MM cells disseminate resistance to BTZ-sensitive MM cells.

METHODS

The serum exosomes were identified by nanoparticle tracking analysis and transmission electron microscopy. Liquid chromatography-mass spectrometry and public databases were performed to screen exosomes HSPA9. Cell counting kit-8, western blotting and colony formation assay were used to detected the role of HSPA9 protein in vitro. Co-immunoprecipitation, immunofluorescence and protein truncation test experiments were used to determine the regulatory network of the HSPA9-USP1-TRIP13 complex. Optical imaging in vivo and xenograft mouse models were performed to investigate that exosomes HSPA9 promoted MM proliferation and BTZ resistance.

RESULTS

We demonstrated that HSPA9 was highly expressed in serum exosomes and BTZ-resistant MM patients. Knockdown of HSPA9 significantly suppressed tumorigenesis and reversed BTZ resistance in vitro. As a downstream molecular of HSPA9, thyroid hormone receptor-interacting protein 13 (TRIP13) was also highly expressed in BTZ-resistant MM patients. Mechanistically, the carboxyl-terminal peptide-binding domain of HSPA9, provides a platform for recruiting the deubiquitinating enzyme ubiquitin-specific peptidase 1 (USP1), which prevents TRIP13 protein degradation. The HSPA9-USP1-TRIP13 complex exhibits stability in the cytoplasm, and its inhibition remarkably enhances BTZ resistance in vito.

CONCLUSION

Our findings propose a pioneering molecular regulatory network in which MM-cell-derived exosomes HSPA9 transmitted BTZ resistance through the USP1/TRIP13 signaling pathway. This research highlights exosomes HSPA9 as a promising target to overcome MM BTZ resistance.

Targeting deubiquitinase USP7-mediated stabilization of XPO1 contributes to the anti-myeloma effects of selinexor

BACKGROUND

Targeting exportin1 (XPO1) with Selinexor (SEL) is a promising therapeutic strategy for patients with multiple myeloma (MM). However, intrinsic and acquired drug resistance constitute great challenges. SEL has been reported to promote the degradation of XPO1 protein in tumor cells. Nevertheless, in myeloma, the precise mechanisms underlying SEL-induced XPO1 degradation and its impact on drug responsiveness remain largely undefined.

METHODS

We assessed XPO1 protein and mRNA levels using western blotting and RT-qPCR. Cycloheximide (CHX) chase assays and degradation blockade assays were used to determine the pathway of XPO1 degradation induced by SEL. The sensitivity of MM cell lines to SEL was evaluated using CCK8-based cell viability assays and AV-PI staining-based cell apoptosis assays. The subcellular localization of the cargo protein RanBP1 was assessed via immunofluorescence staining. Immunoprecipitation coupled with mass spectrometry (IP-MS), bioinformatics analysis and ubiquitination assays, were employed to identify the molecular targets responsible for SEL-induced degradation of XPO1. shRNA-mediated knockdown assays and small molecule inhibitors of USP7 were utilized to disrupt the function of USP7. The role of USP7 in modulating SEL sensitivity was analyzed in MM cell lines, primary CD138+ cells, and xenograft mouse models.

RESULTS

SEL promotes the degradation of XPO1 in MM cells through the ubiquitin-proteasome pathway. There is a positive correlation between XPO1 degradation and sensitivity to SEL in these cells. Inhibiting XPO1 degradation reduces the functional inhibitory effects of SEL on XPO1, as evidenced by decreased nuclear localization of the cargo protein RanBP1. USP7 stabilizes XPO1 in MM cells via its deubiquitinating activity. SEL accelerates the ubiquitination and subsequent degradation of XPO1 by disrupting the interaction between XPO1 and USP7. The expression of USP7 is negatively correlated with patient prognosis and the sensitivity of MM cells to SEL. Inactivating or knocking down USP7 significantly enhances the anti-myeloma effects of SEL both in vitro and in vivo.

CONCLUSION

In conclusion, our findings underscore the essential role of XPO1 degradation in the anti-myeloma efficacy of SEL and establish a research foundation for targeting USP7 to improve the effectiveness of SEL-based therapies in MM.

Role of NEK2 in tumorigenesis and tumor progression

Never in mitosis A (NIMA)-related kinase 2 (NEK2) is a serine/threonine kinase found in the nucleus and cytoplasm throughout the cell cycle. NEK2 is overexpressed in many cancers and is a biomarker of poor prognosis. Factors contributing to NEK2 elevation in cancer cells include oncogenic transcription factors, decreased ubiquitination, DNA methylation, and the circular RNA (circRNA)/long noncoding RNA (lncRNA)-miRNA axis. NEK2 overexpression produces chromosomal instability and aneuploidy, thereby enhancing cancer progression and suppressing antitumor immunity, which highlights the prominence of NEK2 in tumorigenesis and tumor progression. Small-molecule inhibitors targeting NEK2 have demonstrated promising therapeutic potential in vitro and in vivo across various cancer types. This review outlines the regulatory mechanisms of NEK2 expression, emphasizes its functional roles in cancer initiation and progression, and highlights the anticancer properties of NEK2 inhibitors.

TRIP13: A promising cancer immunotherapy target

The tumor microenvironment (TME) facilitates tumor development through intricate intercellular signaling, thereby supporting tumor growth and suppressing the immune response. Thyroid hormone receptor interactor 13 (TRIP13), an AAA+ ATPase, modulates the conformation of client macromolecules, consequently influencing cellular signaling pathways. TRIP13 has been implicated in processes such as proliferation, invasion, migration, and metastasis during tumor progression. Recent studies have revealed that TRIP13 also plays a role in immune response suppression within the TME. Thus, inhibiting these functions of TRIP13 could potentially enhance immune responses and improve the efficacy of immune checkpoint inhibition. This review summarizes the recent research progress of TRIP13 and discusses the potential of targeting TRIP13 to improve immune-based therapies for patients with cancer.

Ubiquitin-specific peptidases in lymphoma: a path to novel therapeutics

Background

Ubiquitin-specific peptidases (USPs), also known as deubiquitinating enzymes (DUBs), play a crucial role in maintaining cellular homeostasis by selectively removing ubiquitin molecules from targeted proteins. This process affects protein stability, subcellular localization, and activity, thereby influencing processes such as DNA repair, cell cycle regulation, and apoptosis. Abnormal USP activities have been linked to various diseases, including cancer. Emerging evidence in lymphoma studies highlights the significance of USPs in controlling signaling pathways related to cancer initiation and progression and presents them as potential therapeutic targets.

Aim

This study aimed to elucidate the multifaceted roles of USPs in lymphoma.

Methods

This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Articles published in English up to May 2023 were retrieved from PubMed, Web of Science, and Scopus. The inclusion criteria focused on studies investigating the role of USPs in lymphoma cancer, involving human subjects or relevant lymphoma cell lines, exploring molecular mechanisms and signaling pathways, and assessing diagnostic or prognostic value.

Results

After the selection process, 23 studies were selected for analysis. USPs were found to affect various aspects of lymphoma development and progression. Specific USPs were identified with roles in cell-cycle regulation, apoptosis modulation, drug resistance, DNA repair, and influence of key oncogenic pathways, such as B cell receptor (BCR) signaling.

Conclusion

This systematic review underscores the emerging role of USPs in lymphoma and their potential as therapeutic targets. Inhibitors of USPs, such as USP14 inhibitors, show promise in overcoming drug resistance. The dynamic interplay between USPs and lymphoma biology presents an exciting opportunity for future research and the development of more effective treatments for patients with lymphoma. Understanding the intricate functions of USPs in lymphoma offers new insights into potential therapeutic strategies, emphasizing the significance of these enzymes in the context of cancer biology.

Tetrahydrocurcumin targets TRIP13 inhibiting the interaction of TRIP13/USP7/c-FLIP to mediate c-FLIP ubiquitination in triple-negative breast cancer

INTRODUCTION

Triple-negative breast cancer (TNBC) has a high mortality rate and limited treatment options. Tetrahydrocurcumin (THC), a major metabolite of curcumin, has potential antitumor activities. However, the antitumor effects and mechanism of THC in TNBC remain elusive.

OBJECTIVES

To investigate the mechanism of THC in combating TNBC by targeting TRIP13 to disrupt the interaction of the TRIP13/USP7/c-FLIP complex and mediate c-FLIP ubiquitination both in vitro and in vivo.

METHODS

Apoptosis was measured by TUNEL and flow cytometry. Click chemistry-based target fishing, CETSA, DARTS, and SPR were used to identify direct target of THC. Protein interactions was examined using co-immunoprecipitation. The role of USP7 in THC-mediated c-FLIP ubiquitination was evaluated by in vitro deubiquitination assay. Human breast cancer clinical samples were employed to assess the expression of c-FLIP, TRIP13, and USP7. The impact of THC on USP7/TRIP13/c-FLIP was analyzed using co-immunoprecipitation, confocal microscopy, molecular docking and dynamics simulations.

RESULTS

THC effectively inhibits TNBC cell proliferation and tumor growth in vitro and in vivo without significant toxicity. Mechanistically, THC induces extrinsic apoptosis in TNBC primarily by promoting degradation of c-FLIP, a key negative regulator in the apoptotic pathway. Furthermore, utilizing click chemistry-based target fishing, we identified TRIP13, a component of the highly conserved AAA ATPase family, as a direct target of THC in combating TNBC. Interestingly, contrary to previous drug-target studies, the knockdown of TRIP13 further amplified the antitumor effects of THC. After in-depth investigation, it was revealed that TRIP13 forms a trimeric complex with USP7 and c-FLIP in TNBC cells. THC specifically targets TRIP13 to disrupt the interaction of TRIP13/USP7/c-FLIP, leading to the ubiquitination of c-FLIP, ultimately inducing extrinsic apoptosis.

CONCLUSIONS

These findings offer new insights into the novel molecular mechanisms of anti-TNBC effects of THC and present a promising targeted therapeutic strategy for TNBC.

Role of TRIP13 in human cancer development

As an AAA + ATPase, thyroid hormone receptor interacting protein 13 (TRIP13) primarily functions in DNA double-strand break repair, chromosome recombination, and cell cycle checkpoint regulation; aberrant expression of TRIP13 can result in chromosomal instability (CIN). According to recent research, TRIP13 is aberrantly expressed in a variety of cancers, and a patient's poor prognosis and tumor stage are strongly correlated with high expression of TRIP13. Tumor cell and subcutaneous xenograft growth can be markedly inhibited by TRIP13 knockdown or TRIP13 inhibitor administration. In the initiation and advancement of human malignancies, TRIP13 seems to function as an oncogene. Based on available data, TRIP13 may function as a biological target and biomarker for cancer. The creation of inhibitors that specifically target TRIP13 may present novel approaches to treating cancer.

TRIP13 - a potential drug target in cancer pharmacotherapy

ATPases Associated with Diverse Cellular Activity (AAA+ATPases) are important enzymatic functional proteins in human cells. Thyroid Hormone Receptor Interacting Protein-13 (TRIP13) is a member of this protein superfamily, that partly regulates DNA repair pathways and spindle assembly checkpoints during mitosis. TRIP13 is reported as an oncogene involving multiple pathways in many human malignancies, including multiple myeloma, brain tumors, etc. The structure of TRIP13 reveals the mechanisms for ATP binding and how TRIP13 recognizes the Mitotic Arrest Deficiency-2 (MAD2) protein, with p31comet acting as an adapter protein. DCZ0415, TI17, DCZ5417, and DCZ5418 are the reported small-molecule inhibitors of TRIP13, which have been demonstrated to inhibit TRIP13's biological functions significantly and effective in suppressing various types of malignant cells, indicating that TRIP13 is a significant anticancer drug target. Currently, no systematic reviews are cutting across the functions, structure, and novel inhibitors of TRIP13. This review provides a comprehensive overview of TRIP13's biological functions, its roles in eighteen different cancers, four small molecule inhibitors, different underlying molecular mechanisms, and its functionality as a potential anticancer drug target.

A Bruton tyrosine kinase inhibitor-resistance gene signature predicts prognosis and identifies TRIP13 as a potential therapeutic target in diffuse large B-cell lymphoma

Bruton tyrosine kinase inhibitor (BTKi) combined with rituximab-based chemotherapy benefits diffuse large B-cell lymphoma (DLBCL) patients. However, drug resistance is the major cause of relapse and death of DLBCL. In this study, we conducted a comprehensive analysis BTKi-resistance related genes (BRRGs) and established a 10-gene (CARD16, TRIP13, PSRC1, CASP1, PLBD1, CARD6, CAPG, CACNA1A, CDH15, and NDUFA4) signature for early identifying high-risk DLBCL patients. The resistance scores based on the BRRGs signature were associated with prognosis. Furthermore, we developed a nomogram incorporating the BRRGs signature, which demonstrated excellent performance in predicting the prognosis of DLBCL patients. Notably, tumor immune microenvironment, biological pathways, and chemotherapy sensitivity were different between high- and low-resistance score groups. Additionally, we identified TRIP13 as a key gene in our model. TRIP13 was found to be overexpressed in DLBCL and BTKi-resistant DLBCL cell lines, knocking down TRIP13 suppresses cell proliferation, promotes cell apoptosis, and enhances the apoptosis effect of BTKi on DLBCL cells by regulating the Wnt/β-catenin pathway. In conclusion, our study presents a novel BRRGs signature that could serve as a promising prognostic marker in DLBCL, and TRIP13 might be a potential therapeutic target for resistant DLBCL.

Removal of the catalytic subunit of DNA-protein kinase in the proximal tubules promotes DNA and tubular damage during kidney injury

Tubular epithelial cell damage can be repaired through a series of complex signaling pathways. An early event in many forms of tubular damage is the observation of DNA damage, which can be repaired by specific pathways depending upon the type of genomic alteration.. In this study, we report that the catalytic subunit of DNA protein kinase (DNA-PKcs), a central DNA repair enzyme involved in sensing DNA damage and performing double stranded DNA break repair, plays an important role in the extent of tubular epithelial cell damage following exposure to injurious acute and chronic stimuli. Selective loss of DNA-PKcs in the proximal tubules led to increased markers of kidney dysfunction, DNA damage, and tubular epithelial cell injury in multiple models of acute kidney injury, specifically bilateral renal ischemia-reperfusion injury and single dose of cisplatin (15 mg/kg IP). In contrast, in a mouse model of kidney fibrosis and chronic kidney disease (UUO),the protective effects of DNA-PKcs was not as obvious histologically from the tissue sections. In the absence of proximal tubular DNA-PKcs, there was reduced levels of fibrotic markers, α-SMA and fibronectin, which suggests that there may be a biphasic role of DNA-PKcs depending upon the conditions exerted upon the kidney. In conclusion, this study demonstrates that the catalytic subunit of DNA-PKcs plays a context-dependent role in the kidney to reduce DNA damage during exposure to various types of acute, but not chronic forms of injurious stimuli.

TRIP13 Plays an Important Role in the Sensitivity of Leukemia Cell Response to Sulforaphane Therapy

Sulforaphane is one of the most characterized isothiocyanate compounds in cruciferous vegetables and shows anticancer effects, especially antileukemia properties. However, the molecular mechanism of the growth inhibition effect of sulforaphane in acute myeloid leukemia (AML) has not been fully explored. In the present study, a proteomic analysis was performed on the AML cell line U937 responding to sulforaphane treatment to identify novel and efficient therapeutic targets of sulforaphane on AML cells. Key driver analysis was run on the leukemia network, and TRIP13 was identified as a key regulatory factor in sulforaphane-induced growth inhibition in U937 cells. Pretreatment with DCZ0415, an inhibitor of TRIP13, could significantly attenuate sulforaphane-induced cell apoptosis and cell cycle arrest in vitro through the PI3K/Akt/mTOR signaling pathway. In addition, the inhibitory effect of sulforaphane on the tumor volume could also be obviously attenuated by the pretreatment of DCZ0415 in vivo. These results indicate that TRIP13 plays an important role in the sensitivity of leukemia cell response to sulforaphane treatment, and these findings expand the understanding of the mechanism of the antileukemic effect of sulforaphane and provide a new target for the treatment of AML.

Ribosomal protein S3 mediates drug resistance of proteasome inhibitor: potential therapeutic application in multiple myeloma

Multiple myeloma (MM) remains incurable due to drug resistance. Ribosomal protein S3 (RPS3) has been identified as a non-Rel subunit of NF-κB. However, the detailed biological roles of RPS3 remain unclear. Here, we report for the first time that RPS3 is necessary for MM survival and drug resistance. RPS3 was highly expressed in MM, and knockout of RPS3 in MM inhibited cell growth and induced cell apoptosis both in vitro and in vivo. Overexpression of RPS3 mediated the proteasome inhibitor resistance of MM and shortened the survival of MM tumor-bearing animals. Moreover, our present study found an interaction between RPS3 and the thyroid hormone receptor interactor 13 (TRIP13), an oncogene related to MM tumorigenesis and drug resistance. We demonstrated that the phosphorylation of RPS3 was mediated by TRIP13 via PKCδ, which played an important role in activating the canonical NF-κB signaling and inducing cell survival and drug resistance in MM. Notably, the inhibition of NF-κB signaling by the small-molecule inhibitor targeting TRIP13, DCZ0415, was capable of triggering synergistic cytotoxicity when combined with bortezomib in drug-resistant MM. This study identifies RPS3 as a novel biomarker and therapeutic target in MM.

Genetic mechanisms of fertilization failure and early embryonic arrest: a comprehensive review

BACKGROUND

Infertility and pregnancy loss are longstanding problems. Successful fertilization and high-quality embryos are prerequisites for an ongoing pregnancy. Studies have proven that every stage in the human reproductive process is regulated by multiple genes and any problem, at any step, may lead to fertilization failure (FF) or early embryonic arrest (EEA). Doctors can diagnose the pathogenic factors involved in FF and EEA by using genetic methods. With the progress in the development of new genetic technologies, such as single-cell RNA analysis and whole-exome sequencing, a new approach has opened up for us to directly study human germ cells and reproductive development. These findings will help us to identify the unique mechanism(s) that leads to FF and EEA in order to find potential treatments.

OBJECTIVE AND RATIONALE

The goal of this review is to compile current genetic knowledge related to FF and EEA, clarifying the mechanisms involved and providing clues for clinical diagnosis and treatment.

SEARCH METHODS

PubMed was used to search for relevant research articles and reviews, primarily focusing on English-language publications from January 1978 to June 2023. The search terms included fertilization failure, early embryonic arrest, genetic, epigenetic, whole-exome sequencing, DNA methylation, chromosome, non-coding RNA, and other related keywords. Additional studies were identified by searching reference lists. This review primarily focuses on research conducted in humans. However, it also incorporates relevant data from animal models when applicable. The results were presented descriptively, and individual study quality was not assessed.

OUTCOMES

A total of 233 relevant articles were included in the final review, from 3925 records identified initially. The review provides an overview of genetic factors and mechanisms involved in the human reproductive process. The genetic mutations and other genetic mechanisms of FF and EEA were systematically reviewed, for example, globozoospermia, oocyte activation failure, maternal effect gene mutations, zygotic genome activation abnormalities, chromosome abnormalities, and epigenetic abnormalities. Additionally, the review summarizes progress in treatments for different gene defects, offering new insights for clinical diagnosis and treatment.

WIDER IMPLICATIONS

The information provided in this review will facilitate the development of more accurate molecular screening tools for diagnosing infertility using genetic markers and networks in human reproductive development. The findings will also help guide clinical practice by identifying appropriate interventions based on specific gene mutations. For example, when an individual has obvious gene mutations related to FF, ICSI is recommended instead of IVF. However, in the case of genetic defects such as phospholipase C zeta1 (PLCZ1), actin-like7A (ACTL7A), actin-like 9 (ACTL9), and IQ motif-containing N (IQCN), ICSI may also fail to fertilize. We can consider artificial oocyte activation technology with ICSI to improve fertilization rate and reduce monetary and time costs. In the future, fertility is expected to be improved or restored by interfering with or supplementing the relevant genes.

The role of ubiquitination and deubiquitination in PI3K/AKT/mTOR pathway: A potential target for cancer therapy

The PI3K/AKT/mTOR pathway controls key cellular processes, including proliferation and tumor progression, and abnormally high activation of this pathway is a hallmark in human cancers. The post-translational modification, such as Ubiquitination and deubiquitination, fine-tuning the protein level and the activity of members in this pathway play a pivotal role in maintaining normal physiological process. Emerging evidence show that the unbalanced ubiquitination/deubiquitination modification leads to human diseases via PI3K/AKT/mTOR pathway. Therefore, a comprehensive understanding of the ubiquitination/deubiquitination regulation of PI3K/AKT/mTOR pathway may be helpful to uncover the underlying mechanism and improve the potential treatment of cancer via targeting this pathway. Herein, we summarize the latest research progress of ubiquitination and deubiquitination of PI3K/AKT/mTOR pathway, systematically discuss the associated crosstalk between them, as well as focus the clinical transformation via targeting ubiquitination process.

Behavior of intracellular lipid droplets during cell division in HuH7 hepatoma cells

Intracellular lipid droplets (LDs) are ubiquitous organelles found in many cell types. During mitosis, membranous organelles, including mitochondria, are divided into small pieces and transferred to daughter cells; however, the process of LD transfer to daughter cells is not fully elucidated. Herein, we investigated the behavior of LDs during mitosis in HuH7 human hepatoma cells. While fragments of the Golgi apparatus were scattered in the cytosol during mitosis, intracellular LDs retained their size and spherical morphology as they translocated to the two daughter cells. LDs were initially distributed throughout the cell during prophase but positioned outside the spindle in metaphase, aligning at the far sides of the centrioles. A similar distribution of LDs during mitosis was observed in another hepatocarcinoma HepG2 cells. When the spindle was disrupted by nocodazole treatment or never in mitosis gene A-related kinase 2A knockdown, LDs were localized in the area outside the chromosomes, suggesting that spindle formation is not necessary for LD localization at metaphase. The amount of major LD protein perilipin 2 reduced while LDs were enriched in perilipin 3 during mitosis, indicating the potential alteration of LD protein composition. Conclusively, the behavior of LDs during mitosis is distinct from that of other organelles in hepatocytes.

The novel norcantharidin derivative DCZ5417 suppresses multiple myeloma progression by targeting the TRIP13-MAPK-YWHAE signaling pathway

BACKGROUND

Multiple myeloma (MM), an incurable disease owing to drug resistance, requires safe and effective therapies. Norcantharidin (NCTD), an active ingredient in traditional Chinese medicines, possesses activity against different cancers. However, its toxicity and narrow treatment window limit its clinical application. In this study, we synthesized a series of derivatives of NCTD to address this. Among these compounds, DCZ5417 demonstrated the greatest anti-MM effect and fewest side effects. Its anti-myeloma effects and  the mechanism were further tested.

METHODS

Molecular docking, pull-down, surface plasmon resonance-binding, cellular thermal shift, and ATPase assays were used to study the targets of DCZ5417. Bioinformatic, genetic, and pharmacological approaches were used to elucidate the mechanisms associated with DCZ5417 activity.

RESULTS

We confirmed a highly potent interaction between DCZ5417 and TRIP13. DCZ5417 inhibited the ATPase activity of TRIP13, and its anti-MM activity was found to depend on TRIP13. A mechanistic study verified that DCZ5417 suppressed cell proliferation by targeting TRIP13, disturbing the TRIP13/YWHAE complex and inhibiting the ERK/MAPK signaling axis. DCZ5417 also showed a combined lethal effect with traditional anti-MM drugs. Furthermore, the tumor growth-inhibitory effect of DCZ5417 was demonstrated using in vivo tumor xenograft models.

CONCLUSIONS

DCZ5417 suppresses MM progression in vitro, in vivo, and in primary cells from drug-resistant patients, affecting cell proliferation by targeting TRIP13, destroying the TRIP13/YWHAE complex, and inhibiting ERK/MAPK signaling. These results imply a new and effective therapeutic strategy for MM treatment.

Current and future directions of USP7 interactome in cancer study

The ubiquitin-proteasome system (UPS) is an essential protein quality controller for regulating protein homeostasis and autophagy. Ubiquitination is a protein modification process that involves the binding of one or more ubiquitins to substrates through a series of enzymatic processes. These include ubiquitin-activating enzymes (E1), ubiquitin-conjugating enzymes (E2), and ubiquitin ligases (E3). Conversely, deubiquitination is a reverse process that removes ubiquitin from substrates via deubiquitinating enzymes (DUBs). Dysregulation of ubiquitination-related enzymes can lead to various human diseases, including cancer, through the modulation of protein ubiquitination. The most structurally and functionally studied DUB is the ubiquitin-specific protease 7 (USP7). Both the TRAF and UBL domains of USP7 are known to bind to the [P/A/E]-X-X-S or K-X-X-X-K motif of substrates. USP7 has been shown to be involved in cancer pathogenesis by binding with numerous substrates. Recently, a novel substrate of USP7 was discovered through a systemic analysis of its binding motif. This review summarizes the currently discovered substrates and cellular functions of USP7 in cancer and suggests putative substrates of USP7 through a comprehensive systemic analysis.

Targeting TRIP13 for overcoming anticancer drug resistance (Review)

Cancer is one of the greatest dangers to human wellbeing and survival. A key barrier to effective cancer therapy is development of resistance to anti‑cancer medications. In cancer cells, the AAA+ ATPase family member thyroid hormone receptor interactor 13 (TRIP13) is key in promoting treatment resistance. Nonetheless, knowledge of the molecular processes underlying TRIP13‑based resistance to anticancer therapies is lacking. The present study evaluated the function of TRIP13 expression in anticancer drug resistance and potential methods to overcome this resistance. Additionally, the underlying mechanisms by which TRIP13 promotes resistance to anticancer drugs were explored, including induction of mitotic checkpoint complex surveillance system malfunction, promotion of DNA repair, the enhancement of autophagy and the prevention of immunological clearance. The effects of combination treatment, which include a TRIP13 inhibitor in addition to other inhibitors, were discussed. The present study evaluated the literature on TRIP13 as a possible target and its association with anticancer drug resistance, which may facilitate improvements in current anticancer therapeutic options.

Deubiquitinating enzyme JOSD2 affects susceptibility of non-small cell lung carcinoma cells to anti-cancer drugs through DNA damage repair

OBJECTIVES

To investigate the effects and mechanisms of deubiquitinating enzyme Josephin domain containing 2 (JOSD2) on susceptibility of non-small cell lung carcinoma (NSCLC) cells to anti-cancer drugs.

METHODS

The transcriptome expression and clinical data of NSCLC were downloaded from the Gene Expression Omnibus. Principal component analysis and limma analysis were used to investigate the deubiquitinating enzymes up-regulated in NSCLC tissues. Kaplan-Meier analysis was used to investigate the relationship between the expression of deubiquitinating enzymes and overall survival of NSCLC patients. Gene ontology enrichment and gene set enrichment analysis (GSEA) were used to analyze the activation of signaling pathways in NSCLC patients with high expression of JOSD2. Gene set variation analysis and Pearson correlation were used to investigate the correlation between JOSD2 expression levels and DNA damage response (DDR) pathway. Western blotting was performed to examine the expression levels of JOSD2 and proteins associated with the DDR pathway. Immunofluorescence was used to detect the localization of JOSD2. Sulforhodamine B staining was used to examine the sensitivity of JOSD2-knock-down NSCLC cells to DNA damaging drugs.

RESULTS

Compared with adjacent tissues, the expression level of JOSD2 was significantly up-regulated in NSCLC tissues (P<0.05), and was significantly correlated with the prognosis in NSCLC patients (P<0.05). Compared with the tissues with low expression of JOSD2, the DDR-related pathways were significantly upregulated in NSCLC tissues with high expression of JOSD2 (all P<0.05). In addition, the expression of JOSD2 was positively correlated with the activation of DDR-related pathways (all P<0.01). Compared with the control group, overexpression of JOSD2 significantly promoted the DDR in NSCLC cells. In addition, DNA damaging agents significantly increase the nuclear localization of JOSD2, whereas depletion of JOSD2 significantly enhanced the sensitivity of NSCLC cells to DNA damaging agents (all P<0.05).

CONCLUSIONS

Deubiquitinating enzyme JOSD2 may regulate the malignant progression of NSCLC by promoting DNA damage repair pathway, and depletion of JOSD2 significantly enhances the sensitivity of NSCLC cells to DNA damaging agents.

TRIP13 overexpression promotes gefitinib resistance in non‑small cell lung cancer via regulating autophagy and phosphorylation of the EGFR signaling pathway

Non‑small cell lung cancer (NSCLC) accounts for the majority of lung cancers and remains the most common cause of cancer‑related death. Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR‑TKIs) have been used as first‑line treatment for patients with NSCLC showing EGFR mutations. Unfortunately, drug resistance is a crucial barrier affecting the treatment of patients with NSCLC. Thyroid hormone receptor interactor 13 (TRIP13) is an ATPase that is overexpressed in numerous tumors and is involved in drug resistance. However, whether TRIP13 plays a role in regulating sensitivity to EGFR‑TKIs in NSCLC remains unknown. TRIP13 expression was evaluated in gefitinib‑sensitive (HCC827) and ‑resistant (HCC827GR and H1975) cell lines. The effect of TRIP13 on gefitinib sensitivity was assessed using the MTS assay. The expression of TRIP13 was upregulated or knocked down to determine its effect on cell growth, colony formation, apoptosis and autophagy. Additionally, the regulatory mechanism of TRIP13 on EGFR and its downstream pathways in NSCLC cells were examined using western blotting, immunofluorescence and co‑immunoprecipitation assays. The expression levels of TRIP13 were significantly higher in gefitinib‑resistant than in gefitinib‑sensitive NSCLC cells. TRIP13 upregulation enhanced cell proliferation and colony formation while reducing the apoptosis of gefitinib‑resistant NSCLC cells, suggesting that TRIP13 may facilitate gefitinib resistance in NSCLC cells. In addition, TRIP13 improved autophagy to desensitize gefitinib in NSCLC cells. Furthermore, TRIP13 interacted with EGFR and induced its phosphorylation and downstream pathways in NSCLC cells. The present study demonstrated that TRIP13 overexpression promotes gefitinib resistance in NSCLC by regulating autophagy and activating the EGFR signaling pathway. Thus, TRIP13 could be used as a biomarker and therapeutic target for gefitinib resistance in NSCLC.

The equilibrium of tumor suppression: DUBs as active regulators of PTEN

PTEN is among the most commonly lost or mutated tumor suppressor genes in human cancer. PTEN, a bona fide lipid phosphatase that antagonizes the highly oncogenic PI3K-AKT-mTOR pathway, is considered a major dose-dependent tumor suppressor. Although PTEN function can be compromised by genetic mutations in inherited syndromes and cancers, posttranslational modifications of PTEN may also play key roles in the dynamic regulation of its function. Notably, deregulated ubiquitination and deubiquitination lead to detrimental impacts on PTEN levels and subcellular partitioning, promoting tumorigenesis. While PTEN can be targeted by HECT-type E3 ubiquitin ligases for nuclear import and proteasomal degradation, studies have shown that several deubiquitinating enzymes, including HAUSP/USP7, USP10, USP11, USP13, OTUD3 and Ataxin-3, can remove ubiquitin from ubiquitinated PTEN in cancer-specific contexts and thus reverse ubiquitination-mediated PTEN regulation. Researchers continue to reveal the precise molecular mechanisms by which cancer-specific deubiquitinases of PTEN regulate its roles in the pathobiology of cancer, and new methods of pharmacologically for modulating PTEN deubiquitinases are critical areas of investigation for cancer treatment and prevention. Here, we assess the mechanisms and functions of deubiquitination as a recently appreciated mode of PTEN regulation and review the link between deubiquitinases and PTEN reactivation and its implications for therapeutic strategies.

Proteomic profiling reveals CDK6 upregulation as a targetable resistance mechanism for lenalidomide in multiple myeloma

The immunomodulatory drugs (IMiDs) lenalidomide and pomalidomide are highly effective treatments for multiple myeloma. However, virtually all patients eventually relapse due to acquired drug resistance with resistance-causing genetic alterations being found only in a small subset of cases. To identify non-genetic mechanisms of drug resistance, we here perform integrated global quantitative tandem mass tag (TMT)-based proteomic and phosphoproteomic analyses and RNA sequencing in five paired pre-treatment and relapse samples from multiple myeloma patients. These analyses reveal a CDK6-governed protein resistance signature that includes myeloma high-risk factors such as TRIP13 and RRM1. Overexpression of CDK6 in multiple myeloma cell lines reduces sensitivity to IMiDs while CDK6 inhibition by palbociclib or CDK6 degradation by proteolysis targeting chimeras (PROTACs) is highly synergistic with IMiDs in vitro and in vivo. This work identifies CDK6 upregulation as a druggable target in IMiD-resistant multiple myeloma and highlights the use of proteomic studies to uncover non-genetic resistance mechanisms in cancer.

Acquired resistance to immunomodulatory drugs is common in multiple myeloma patients, but rarely attributed to genetic alterations. Here, proteomic, phosphoproteomic and RNA sequencing analysis in five paired pre-treatment and relapse samples reveals a CDK6-regulated protein resistance signature.