ERK and USP5 govern PD-1 homeostasis via deubiquitination to modulate tumor immunotherapy

Synthesis of USP5-IN-1 derivatives as novel USP5 inhibitors with potent activity against cholangiocarcinoma cells

USP5 is a crucial deubiquitinase involved in regulating various pathophysiological processes, including DNA damage repair, immune responses, pathological pain, and, most notably, oncogenesis. Despite the considerable clinical potential of USP5-targeted inhibitors, their development remains in the early stages. USP5-IN-1 (also known as compound 64) stands out from other USP5 inhibitors due to its reported high selectivity for USP5 and its specific co-crystal structure with the USP5 ZnF-UBD (PDB: 7MS7). However, the activity of USP5-IN-1 has only been validated in vitro through the inhibition of USP5-catalyzed cleavage of a di-ubiquitin substrate, with its cell membrane penetration ability and intracellular activity still unverified. In this study, we structurally modified USP5-IN-1 to enhance its cell membrane penetration and inhibitory activity against USP5, and synthesized fifteen USP5-IN-1 derivatives (compounds 1a-1j, 2a-2d, and 3a). Compared to USP5-IN-1, compounds 1a and 1h exhibited enhanced inhibitory effects on USP5 deubiquitinase activity, as well as on the proliferation and metastasis of cholangiocarcinoma cells. Mechanistically, 1a and 1h significantly inhibited the mTORC1 and Erk1/2 pathways in HCCC9810 cells, without affecting the activation of PKCα, β-catenin or FAK, a pattern consistent with the effects of direct USP5 knockdown. Furthermore, both of the compounds, along with USP5 knockdown, significantly induced cell cycle arrest, apoptosis and ferroptosis. In-silico studies revealed that compounds 1a and 1h had significantly lower binding free energies and larger octanol-water partition coefficients than USP5-IN-1, indicating stronger affinity for USP5 and improved cell membrane penetration. We believe compounds 1a and 1h are promising USP5 inhibitors and merit further investigation.

A pathological missense mutation in the deubiquitinase USP5 leads to insensitivity to pain

Cav3.2 T-type calcium channels and their dysregulation by the deubiquitinase USP5 contribute to development of inflammatory and neuropathic pain. We report on a pediatric patient with a de novo heterozygous missense mutation R24W in USP5 who exhibits pain insensitivity. We created a CRISPR knock-in mouse harboring this mutation and performed detailed behavioral analyses in acute and chronic pain models. Heterozygous R24W mice of both sexes are resistant to acute pain and to thermal hypersensitivity in chronic inflammatory and neuropathic pain models. In contrast, only male R24W mice confer resistance to development of mechanical hypersensitivity. R24W mice lack upregulation of Cav3.2 and USP5 that is normally observed with CFA-induced inflammation. Moreover, mutant USP5 exhibits a dramatic reduction in enzymatic activity but stronger interactions with Cav3.2. Hence, R24W mutant USP5 is a critical regulator of chronic and acute pain states in humans by acting as a dominant-negative regulator of Cav3.2. Our data validate USP5 as a potential therapeutic target for chronic pain in humans.

USP5 Stabilizes IKBKG Through Deubiquitination to Suppress Ferroptosis and Promote Growth in Non-small Cell Lung Cancer

Ferroptosis, a distinctive modality of cell mortality, has emerged as a critical regulator in non-small cell lung cancer (NSCLC). The deubiquitinating enzyme USP5 has established an oncogenic role in NSCLC. However, its biological relevance in NSCLC cell ferroptosis is currently unexplored. Expression analysis was performed by quantitative PCR (qPCR), immunohistochemistry (IHC) and immunoblotting. Animal xenograft studies were used to detect USP5's role in tumor growth. Cell proliferation, colony formation and apoptotic ratio were assessed by CCK-8, colony formation and flow cytometry assays, respectively. Cell ferroptosis was evaluated by gauging ROS, MDA, GSH, SOD, and Fe2+ contents. The USP5/IKBKG relationship and the ubiquitinated IKBKG were evaluated by Co-IP experiments. USP5 expression was elevated in human NSCLC. USP5 depletion suppressed NSCLC cell in vitro and in vivo growth and enhanced cell apoptosis. Moreover, USP5 depletion induced ferroptosis in NSCLC cell lines. Mechanistically, USP5 could enhance the stability of IKBKG protein through deubiquitination. Re-expression of IKBKG partially but significantly abolished USP5 depletion-mediated anti-growth and pro-ferroptosis effects in NSCLC cells. Our study demonstrates that USP5 suppresses ferroptosis and enhances growth in NSCLC cells by stabilizing IKBKG protein through deubiquitination. Targeting USP5 expression is an encouraging strategy to block NSCLC progression.

Targeting PD-1 post-translational modifications for improving cancer immunotherapy

Programmed cell death protein 1 (PD-1) is a critical immune checkpoint receptor that suppresses immune responses largely through its interaction with PD-L1. Tumors exploit this mechanism to evade immune surveillance, positioning immune checkpoint inhibitors targeting the PD-1/PD-L1 axis as groundbreaking advancements in cancer therapy. However, the overall effectiveness of these therapies is often constrained by an incomplete understanding of the underlying mechanisms. Recent research has uncovered the pivotal role of various post-translational modifications (PTMs) of PD-1, including ubiquitination, UFMylation, phosphorylation, palmitoylation, and glycosylation, in regulating its protein stability, localization, and protein-protein interactions. As much, dysregulation of these PTMs can drive PD-1-mediated immune evasion and contribute to therapeutic resistance. Notably, targeting PD-1 PTMs with small-molecule inhibitors or monoclonal antibodies (MAbs) has shown potential to bolster anti-tumor immunity in both pre-clinical mouse models and clinical trials. This review highlights recent findings on PD-1's PTMs and explores emerging therapeutic strategies aimed at modulating these modifications. By integrating these mechanistic insights, the development of combination cancer immunotherapies can be further rationally advanced, offering new avenues for more effective and durable treatments.

Mechanical signal modulates prostate cancer immune escape by USP8-mediated ubiquitination-dependent degradation of PD-L1 and MHC-1

The tumor environment of prostate cancer (PCa) tissues of high Gleason score has been proved to be more immune suppressive and has higher extracellular matrix (ECM) stiffness, but whether ECM mechanical stiffness is the cause of higher ability of invasiveness and immune escape of PCa with high Gleason score remains uncertain. In this study, we showed that higher polyacrylamide hydrogels (PAAG) stiffness resulted in the progression and immune escape of PCa via integrin β1/FAK/YAP axis. The translocation of YAP into cell nucleus to bind to TEAD2 promoted the transcriptional activation of USP8. NBR1 could be ubiquitinated, and then degraded, via interacting with P62/SQSTM1 and through autophagy-lysosome pathway. Increased expression of USP8 promoted the abundance of NBR1 via K63-linked de-ubiquitination and PD-L1 via K48-linked de-ubiquitination in response to high PAAG stiffness. NBR1-mediated selective autophagy accelerated the degradation of MHC-1 of PCa. The USP8 inhibitor presented a potential application value in sensitizing immunotherapy of PCa. Taken together, we identified a USP8-mediated de-ubiquitination mechanism that involves in the process of high PAAG stiffness-mediated high expression of PD-L1 and low expression of MHC-1 of PCa cells, which provided a rationale of immunotherapy sensitization of PCa via USP8 inhibition.

SP1 promotes triple-negative breast cancer progression by targeting USP5

BACKGROUND

Triple-negative breast cancer (TNBC) is characterized by the absence of targeted therapies and a dismal prognosis, necessitating a critical exploration of the molecular mechanisms driving TNBC pathogenesis and the identification of novel therapeutic targets. While dysregulated USP5 expression has been observed in various malignancies, its specific functions and mechanisms in TNBC remain poorly understood.

METHODS

The study utilized a combination of TCGA database analysis, immunohistochemistry staining (IHC), quantitative RT-PCR, and western blotting assay to investigate the expression of USP5 and SP1 in TNBC. Furthermore, the study examined the role of the SP1-USP5 axis and the USP5 inhibitor periplocin in TNBC progression through CCK-8 assay, colony formation assay, EDU incorporation assay, and tumor xenograft experiments. Additionally, the study explored the underlying mechanisms involved in the regulation of USP5 expression in TNBC using luciferase assay, ChIP-qPCR, quantitative RT-PCR, and western blotting assay. In order to ascertain potential inhibitors of USP5 activity, a combination of the Molecular Operating Environment (MOE) multi-functional docking platform, cellular thermal shift assay, and in vitro USP5 activity assay were utilized.

RESULTS

In the current investigation, it was observed that the expression of USP5 was elevated in TNBC and was significantly correlated with decreased overall survival rates among patients. The upregulation of USP5 was found to be mediated by the transcription factor SP1 through its binding to the USP5 promoter, consequently facilitating the progression of TNBC. Notably, the natural compound periplocin was identified as a promising inhibitor of USP5, demonstrating potential efficacy in impeding the advancement of TNBC.

CONCLUSIONS

Our research findings indicate that the SP1-USP5 signaling pathway is significantly involved in the advancement of TNBC, and periplocin's ability to target USP5 presents a potential therapeutic approach for managing TNBC. These results offer valuable insights for the development of novel treatment strategies for TNBC patients.

Therapeutic potential of targeting ubiquitin-specific proteases in colorectal cancer

Ubiquitin-specific proteases (USPs) are a subset of deubiquitinating enzymes (DUBs) that have crucial roles in regulating key signaling pathways, DNA repair mechanisms, and immune responses by modulating the interactions and stability of proteins, including oncogenes and tumor suppressors in many cancers, such as colorectal cancer (CRC). USPs present an attractive reservoir of drug targets that could potentially overcome the shortcomings of conventional pathway-specific cancer therapies. This review explores the roles of USPs in CRC, addresses the challenges in discovering and developing USP inhibitors, highlights recent advancements in drug development, and discusses the potential of targeted protein degraders and stabilizers including proteolysis-targeting chimeras (PROTACs), molecular glues, and DUB-targeting chimeras (DUBTACs) as strategies for drugging USPs.

USP5 motivates immunosuppressive microenvironment in multiple myeloma by activating STAT2-PFKFB4-mediated glycolysis

BACKGROUND

Glycolysis, a classic characteristic of cancer cells, can drive cancer progression by generating lactate, which play as a key immunosuppressive mediator. Currently, ubiquitin-specific proteases 5 (USP5) has been demonstrated to facilitate tumor cell survival in multiple myeloma (MM), whereas whether USP5 was involved in glycolysis-lactate production pathway and immunosuppressive microenvironment formation in MM remain unknown.

METHODS

The gene and protein expression characteristics were assessed via qRT-PCR and western blot. MM cell survival was determined by CCK-8 and flow cytometry analysis. Glycolysis was evaluated by examining glucose uptake, lactate production and ATP level via corresponding kits. Tumor-associated macrophages polarization was tested via measurement of M1/M2-like macrophage markers using qRT-PCR and flow cytometry methods. Dual-luciferase reporter, chromatin immunoprecipitation and co-immunoprecipitation assays were conducted to verified molecular relationship. Xenograft model was used for verified cellular findings.

RESULTS

USP5 was abnormally overexpressed in MM patients and cell lines. Knockdown of USP5 could restrain MM cell survival and glycolysis activity, thus reducing lactate-mediated immunosuppressive M2-like macrophage polarization in vitro and in vivo, whereas overexpression of USP5 play opposite impacts. Mechanistically, USP5 could downregulate the ubiquitination modification of STAT to stabilize STAT2 protein, thus activating PFKFB4 transcription. Moreover, STAT2 could overturn the regulatory role of USP5 on MM cell survival, glycolysis and lactate-mediated immunosuppressive M2-like macrophage polarization.

CONCLUSION

These findings elucidated that USP5 served as a regulator of glycolysis-lactate to stimulate M2-like macrophage formation by regulating STAT2-PFKFB4 signaling, which supported that USP5 could be a viable therapeutic target of MM treatment.

Identification of USP39 as a prognostic and predictive biomarker for determining the response to immunotherapy in pancreatic cancer

Ubiquitin-Specific Protease 39 (USP39) has been implicated in numerous malignancies, however, its pathogenic mechanisms and impact on the tumor immune microenvironment (TIME) remain incompletely characterized. Based on The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) databases, we investigated the diagnostic and prognostic values of USP39 across various cancer types. Additionally, we examined the correlation between USP39 expression and immune-related gene signature, immune cell infiltration pattern, tumor microsatellite instability (MSI), and tumor mutation burden (TMB). This study specifically focused on exploring the clinical relevance and molecular functions of USP39 in pancreatic adenocarcinoma (PAAD), with particularly emphasis on its role in shaping the TIME and modulating responses to immunotherapy. The results demonstrated that evaluated USP39 expression significantly correlated with advanced tumor stage and unfavorable clinical outcomes across multiple cancer types, most notably in PAAD. Functional enrichment analysis indicated that USP39 potentially promotes tumor progression through multiple oncogenic signaling cascades. In vitro experimental validation confirmed that USP39 knockdown inhibited migration and proliferation of pancreatic cancer cells while inducing apoptosis. Additionally, we identified significant positive correlations between USP39 expression and immune checkpoint molecules, particularly prominent in PAAD. Furthermore, we observed associations between USP39 expression and TMB in 16 cancer types and MSI in 11 cancer types, suggesting that heightened USP39 expression may enhance responsiveness to immunotherapeutic interventions. Collectively, our findings establish USP39 as a valuable immune-related biomarker with both diagnostic and prognostic utility across multiple cancer types, especially PAAD, underscoring its potential as a promising therapeutic target for cancer immunotherapy. Clinical trial number Not applicable.

Deubiquitinase USP24 activated by IL-6/STAT3 enhances PD-1 protein stability and suppresses T cell antitumor response

Persisting programmed cell death-1 (PD-1) signaling impairs T cell effector function, which is highly associated with T cell exhaustion and immunotherapy failure. However, the mechanism responsible for PD-1 deubiquitination and T cell dysfunction remains unclear. Here, we show that ubiquitin-specific peptidase 24 (USP24) promotes PD-1 protein stability by removing K48-linked polyubiquitin. Increased interleukin-6 level transcriptionally activates the USP24 expression, which leads to PD-1 stabilization. Furthermore, USP24 deficiency reduces PD-1 levels in CD8+ T cells and attenuates EgfrL858R-driven lung tumorigenesis in Usp24C1695A catalytic deficient mice. Targeting PD-1 stability with the USP24-specific inhibitor USP24-i-101 boosts cytotoxic T cell activity, restrains lung tumor growth, and achieves superior therapeutic effects when combined with anti-CTLA4 immunotherapy. Clinically, patients with lung cancer exhibiting high USP24 expression in tumor-infiltrating CD8+ T cells display exhausted features and show unfavorable responses to immunotherapy. Our findings dissect the mechanism for regulating enhanced PD-1 stability in tumor-infiltrating CD8+ T cells and reveal USP24 as a potential target of antitumor immunotherapy.

Gut microbiota affects PD-L1 therapy and its mechanism in melanoma

Immune checkpoint inhibitors (ICIs), particularly PD-1/PD-L1 blockade, have shown great success in treating melanoma. PD-L1 (B7-H1, CD274), a ligand of PD-1, binds to PD-1 on T cells, inhibiting their activation and proliferation through multiple pathways, thus dampening tumor-reactive T cell activity. Studies have linked PD-L1 expression in melanoma with tumor growth, invasion, and metastasis, making the PD-1/PD-L1 pathway a critical target in melanoma therapy. However, immune-related adverse events are common, reducing the effectiveness of anti-PD-L1 treatments. Recent evidence suggests that the gut microbiome significantly influences anti-tumor immunity, with the microbiome potentially reprogramming the tumor microenvironment and overcoming resistance to anti-PD-1 therapies in melanoma patients. This review explores the mechanisms of PD-1/PD-L1 in melanoma and examines how gut microbiota and its metabolites may help address resistance to anti-PD-1 therapy, offering new insights for improving melanoma treatment strategies.

Modulating the PD-1-FABP5 axis in ILC2s to regulate adipose tissue metabolism in obesity

Obesity is closely linked to metabolic dysregulation and chronic inflammation, which significantly impact immune cell functions in adipose tissue. Type 2 innate lymphoid cells (ILC2s) have emerged as key regulators of energy homeostasis, positioning them as promising targets for obesity management. However, the mechanisms governing ILC2 activity and their therapeutic potential in obesity are not fully understood. In this study, we demonstrate that ILC2s in obese adipose tissue exhibit increased PD-1 expression, leading to an exhausted phenotype with diminished cytokine production and proliferation. Elevated osteopontin (OPN) levels in adipose tissue are associated with higher PD-1 expression on ILC2s, while adipocyte-derived PD-L1 interacts with PD-1 to further impair ILC2 functionality. Importantly, blocking PD-1 signaling prevents weight gain and alleviates obesity-related metabolic dysfunctions. In addition, the adoptive transfer of PD-1-deficient ILC2s reduces diabetic phenotypes in obese models. Mechanistically, PD-1 signaling drives metabolic reprogramming in ILC2s, affecting fatty acid uptake and energy metabolism through the downregulation of fatty acid binding protein 5 (FABP5). These results, corroborated by findings in human adipose tissue, suggest a conserved OPN-PD-1 axis. Our study identifies the OPN-PD-1-FABP5 pathway as a crucial regulator of ILC2 function in adipose tissue and presents an emerging immune cell-based therapeutic target for obesity treatment.

USP5 deubiquitinates and stabilizes IMPDH2, to promote hepatocellular carcinoma progression

Modulating deubiquitinase activity is an emerging therapeutic approach for cancer. In this study, ubiquitin-specific protease 5 (USP5), a deubiquitinase, was found to be frequently overexpressed in hepatocellular carcinoma (HCC) and associated with poor prognosis in patients with HCC. Inosine monophosphate dehydrogenase 2 (IMPDH2) was identified as a binding partner of USP5. USP5 N-terminal domain (cryptic ZnF-UBP and ZnF-UBP domain) interacted with IMPDH2 (251-514 aa). IMPDH2 positively correlated with USP5 expression in HCC. Mechanistically, USP5 removed Lys48-linked ubiquitin chains from IMPDH2 through its deubiquitinase activity, preventing its ubiquitin-mediated degradation and stabilizing IMPDH2. The USP5-IMPDH2 axis promoted HCC proliferation, and metastasis mediated by epithelial-mesenchymal transition (EMT) process in HCC cells and Huh7 xenograft tumors in zebrafish. Notably, GTP biosynthesis pathway was involved in HCC progression induced by USP5. Furthermore, administration of WP1130, a USP5 inhibitor, or IMPDH2 reduction by shRNA facilitated the tumor-suppressive role of sorafenib in HCC cells and Huh7 xenograft tumors in nude mice. Together, we identified IMPDH2 as a substrate of USP5, which participates in USP5 induced promotion of HCC progression. Targeting the USP5-IMPDH2 axis might offer potential therapeutic benefits for patients with HCC.

eIF3f promotes tumour malignancy by remodelling fatty acid biosynthesis in hepatocellular carcinoma

BACKGROUND & AIMS

Fatty acid metabolism is closely associated with hepatocellular carcinoma (HCC). Elucidating the molecules that influence fatty acid metabolism in HCC is important for developing precision therapies. However, uncovering the precise molecular mechanisms underlying changes in fatty acid metabolism in tumour cells is challenging. In this study, we aimed to determine the characteristics of fatty acid metabolism in HCC.

METHODS

We employed organoid models, single-cell RNA sequencing, and spatial transcriptomics to identify key genes involved in tumour fatty acid metabolism. Metabolomics, proteomics, metabolic flux analysis, and transmission electron microscopy were utilized to evaluate this metabolic process. Tumour malignancy was characterized using multi-species models. Changes in the immune microenvironment were analysed by time-of-flight mass cytometry and multiplexed immunohistochemistry. Gene knockdown targeting the liver was achieved using lipid nanoparticles.

RESULTS

Eukaryotic translation initiation factor 3 subunit f (eIF3f) is upregulated in HCC tissues and is associated with poor prognosis. eIF3f directly interacted with and stabilised long chain acyl CoA synthetase 4 (ACSL4) through K48-linked deubiquitination, promoting fatty acid biosynthesis and malignancy. The increased fatty acid levels in the tumour microenvironment indirectly reduced CD8+ T-cell infiltration. In addition, phosphorylated eIF3f enhanced the interaction between eIF3f and ACSL4.

CONCLUSIONS

Targeting the eIF3f-ACSL4-fatty acid biosynthesis axis could decelerate the progression of HCC and enhance anti-programmed cell death-1 efficacy, implicating eIF3f as a potential target for precision therapy in HCC.

IMPACT AND IMPLICATIONS

Fatty acid metabolism is closely associated with hepatocellular carcinoma (HCC), yet the underlying mechanisms involved remain unclear. Here, we found that eIF3f is upregulated in HCC and is associated with poor prognosis. eIF3f interacts with and stabilizes ACSL4, thereby promoting fatty acid biosynthesis. Additionally, increased fatty acid levels reduce CD8+ T-cell infiltration and activation. These findings are of significant importance for clinicians and researchers in the field of HCC treatment, as eIF3f inhibition combined with anti-PD-1 therapy significantly improved anti-tumour efficacy in a mouse model and could offer therapeutic benefits for patients. These findings have practical implications, as eIF3f could serve as a novel therapeutic target in HCC. However, further clinical studies are needed to confirm the efficacy of eIF3f targeting in human patients.

Classification of lung adenocarcinoma based on senescence-related genes identifies a cluster with immunotherapy resistance and poor prognosis

Lung adenocarcinoma is one of the major contributors to cancer-related mortality, with immunotherapy emerging as a key treatment. However, many patients exhibit resistance to immune checkpoint inhibitors. Cellular senescence has been linked to tumor progression and drug resistance, influencing the tumor microenvironment. This study applied consensus clustering to classify lung adenocarcinoma patients into two clusters based on senescence-related gene expression, revealing differing immune characteristics. One of the identified clusters exhibited immunosuppressive characteristics and showed resistance to immunotherapy. A senescence-related risk score was developed using machine learning to predict immunotherapy response and prognosis. High senescence-related risk score correlated with poorer survival and increased immunotherapy resistance across multiple cancer types. The senescence-related risk score model showed robust predictive ability in both the training and validation cohorts. These findings suggest a link between senescence and immunotherapy resistance, and further investigation into their relationship could reveal new perspectives for cancer treatment.

USP5 Promotes Head and Neck Squamous Cell Carcinoma Progression via mTOR Signaling Pathway

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is a highly aggressive malignancy characterized by limited prognostic markers and treatment options, contributing to high mortality rates. While Ubiquitin-specific peptidase 5 (USP5) has been implicated in various cancers, its role in HNSCC remains poorly understood.

AIMS

This study aims to investigate the role of USP5 in the progression of HNSCC and explore its potential as both a prognostic biomarker and a therapeutic target.

MATERIALS & METHODS

This work utilized single-cell transcriptomic analysis with the Scissor algorithm to identify distinct epithelial subpopulations, particularly focusing on the Stress subpopulation that exhibited significant upregulation of USP5. Validation was conducted using tissue microarray (TMA) analysis and immunohistochemistry (IHC) to compare USP5 expression levels in HNSCC tissues versus adjacent normal tissues. Furthermore, RNA interference (RNAi) experiments were performed to knock down USP5 expression, assessing its effects on tumor cell behavior, including proliferation, migration, and invasion, as well as the regulation of mTORC1 and NF-κB signaling pathways.

RESULTS

This study revealed that the Stress subpopulation, characterized by USP5 upregulation, was associated with enhanced tumor cell proliferation, migration, and invasion. TMA and IHC analyses confirmed that USP5 expression was significantly higher in HNSCC tissues compared to normal tissues, correlating with poor patient prognosis. Additionally, RNAi-mediated knockdown of USP5 led to reduced tumor cell activities and downregulation of the mTORC1 and NF-κB signaling pathways.

DISCUSSION

The findings suggest that USP5 plays a critical role in driving HNSCC progression. Its overexpression in aggressive tumor subpopulations and association with poor clinical outcomes highlight its potential utility as both a prognostic biomarker and a therapeutic target. The observed effects on cell behavior and oncogenic signaling pathways provide mechanistic insights into how USP5 for HNSCC therapy.

CONCLUSIONS

This study establishes USP5 as a key driver of HNSCC progression, underscoring its potential role in prognosis and therapy. Targeting USP5 may offer novel treatment strategies for HNSCC, addressing the urgent need for effective therapeutic interventions in this aggressive malignancy.

Unravelling the role of ubiquitin-specific proteases in breast carcinoma: insights into tumour progression and immune microenvironment modulation

Breast cancer is a prevalent malignancy worldwide, and its treatment has increasingly shifted towards precision medicine, with immunotherapy emerging as a key therapeutic strategy. Deubiquitination, an essential epigenetic modification, is regulated by deubiquitinating enzymes (DUBs) and plays a critical role in immune function and tumor progression. Ubiquitin-specific proteases (USPs), a prominent subgroup of DUBs, are involved in regulating immune cell functions, antigen processing, and T cell development in the context of breast cancer. Certain USPs also modulate the differentiation of immune cells, such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs), within the breast cancer immune microenvironment. Furthermore, several USPs influence the expression of PD-L1, thus affecting the efficacy of immune checkpoint inhibitors. The overexpression of USPs may promote immune evasion, contributing to the development of treatment resistance. This review elucidates the role of USPs in modulating the immune microenvironment and immune responses in breast cancer. Additionally, it discusses effective strategies for combining USP inhibitors with other therapeutic agents to enhance treatment outcomes. Therefore, targeting USPs presents the potential to enhance the efficacy of immunotherapy and overcome drug resistance, offering a more effective treatment strategy for breast cancer patients.

Post-translational modifications in hepatocellular carcinoma: unlocking new frontiers in immunotherapy

Liver cancer, particularly hepatocellular carcinoma (HCC), is one of the most common and aggressive malignancies worldwide. Immunotherapy has shown promising results in treating HCC, but its efficacy is often limited by complex mechanisms of immune evasion. Post-translational modifications (PTMs) of proteins play a critical role in regulating the immune responses within the tumor microenvironment (TME). These modifications influence protein function, stability, and interactions, which either promote or inhibit immune cell activity in cancer. In this mini-review, we explore the diverse PTMs that impact immune evasion in liver cancer, including glycosylation, phosphorylation, acetylation, and ubiquitination. We focus on how these PTMs regulate key immune checkpoint molecules such as PD-L1, CTLA-4, and the TCR complex. Furthermore, we discuss the potential of targeting PTMs in combination with existing immunotherapies to enhance the effectiveness of treatment in HCC. Understanding the role of PTMs in immune regulation may lead to the development of novel therapeutic strategies to overcome resistance to immunotherapy in liver cancer.

USP5 stabilizes YTHDF1 to control cancer immune surveillance through mTORC1-mediated phosphorylation

The N6-methyladenosine binding protein YTHDF1, often upregulated in cancer, promotes tumor growth and hinders immune checkpoint blockade treatment. A comprehensive understanding of the molecular mechanisms governing YTHDF1 protein stability is pivotal for enhancing clinical response rates and the effectiveness of immune checkpoint blockade in cancer patients. Here, we report that USP5 interacts with YTHDF1, stabilizing it by removing K11-linked polyubiquitination. Insulin activates mTORC1, phosphorylating USP5 and promoting its dimerization, which binds to and protects YTHDF1 from degradation. Conversely, the CUL7-FBXW8 E3 ligase promotes YTHDF1 degradation. Deficiency in YTHDF1 or USP5 increases PD-L1 expression and suppresses immune-related gene expression, facilitating immune evasion. Combining USP5 inhibition with anti-PD-L1 therapy enhances anti-tumor immunity, suggesting USP5 as a potential biomarker for patient stratification. This study reveals a ubiquitination-dependent regulation of YTHDF1, proposing USP5 inhibition alongside PD-(L)1 blockade as a promising cancer treatment strategy.

The epitranscriptional factor PCIF1 orchestrates CD8+ T cell ferroptosis and activation to control antitumor immunity

T cell-based immunotherapies have revolutionized cancer treatment, yet durable responses remain elusive. Here we show that PCIF1, an RNA N6 2'-O-dimethyladenosine (m6Am) methyltransferase, negatively regulates CD8+ T cell antitumor responses. Whole-body or T cell-specific Pcif1 knockout (KO) reduced tumor growth in mice. Single-cell RNA sequencing shows an increase in the number of tumor-infiltrating cytotoxic CD8+ T cells in Pcif1-deficient mice. Mechanistically, proteomic and m6Am-sequencing analyses pinpoint that Pcif1 KO elevates m6Am-modified targets, specifically ferroptosis suppressor genes (Fth1, Slc3a2), and the T cell activation gene Cd69, imparting resistance to ferroptosis and enhancing CD8+ T cell activation. Of note, Pcif1-deficient mice had enhanced responses to anti-PD-1 immunotherapy, and Pcif1 KO chimeric antigen receptor T cells improved tumor control. Clinically, cancer patients with low PCIF1 expression in T cells have enhanced responses to immunotherapies. These findings suggest that PCIF1 suppresses CD8+ T cell activation and targeting PCIF1 is a promising strategy to boost antitumor immunity.

LRP11 facilitates lipid metabolism and malignancy in hepatocellular carcinoma by stabilizing RACK1 through USP5 regulation

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide and a major public health challenge. Lipid metabolism plays a crucial role in the metabolic reprogramming observed in HCC, although the underlying mechanisms are still being elucidated. Nile red staining and lipid assays showed that LRP11 knockdown significantly reduces lipid accumulation in HCC cells, with a concurrent decrease in key lipid metabolism markers such as FSAN, ACLY and ACSL4, as demonstrated by Western blotting. Mass spectrometry (MS) and co-immunoprecipitation (Co-IP) revealed that LRP11 recruits USP5, enhancing USP5-mediated deubiquitination of RACK1. Truncation analysis identified LRP11 residues 309-500 as critical for interaction with the RACK1 residues 91-231. These findings suggest that LRP11 may influence lipid metabolism and progression in HCC through USP5-mediated stabilization of RACK1. Based on these results, LRP11 emerges as a potential target for further exploration in HCC therapy. Targeting LRP11 or disrupting its interactions with USP5 or RACK1 could offer new avenues for treatment, though additional research is required to validate these therapeutic possibilities.

Progress in understanding the regulatory mechanisms of immune checkpoint proteins PD-1 and PD-L1 expression

Programmed Death Protein-1 (PD-1) is a cell surface receptor that serves as a checkpoint for T cells, playing a pivotal role in regulating T-cell apoptosis. The binding of PD-1 to its ligand, Programmed Death Ligand 1 (PD-L1), inhibits anti-tumor immunity by suppressing T-cell activation signals. Indeed, the PD-1/PD-L1 pathway governs the induction and maintenance of immune tolerance within the tumor microenvironment. Consequently, the regulation of PD-1/PD-L1 immune checkpoint expression is of paramount importance. This review summarizes the mechanisms governing PD1/PD-L1 expression at various stages, including transcription, post-transcription (mRNA processing), and post-translation (protein modifications), as well as immunotherapy targeting PD1/PD-L1, aiming to further explore novel strategies for tumor immunotherapy.

USP5 promotes tumor progression by stabilizing SLUG in bladder cancer

Bladder cancer ranks as the second most prevalent urology malignancy globally. Invasive metastasis is a significant contributor to mortality among patients with bladder cancer, yet the underlying mechanisms remain elusive. Deubiquitinases are pivotal in carcinogenesis, with USP5 implicated in the malignant progression of hepatocellular carcinoma, colorectal cancer and non-small cell lung cancer. The present study assessed the role and mechanism of ubiquitin-specific proteinase 5 (USP5) in the malignant progression of bladder cancer. The association between USP5 expression and bladder cancer prognosis and stage was analyzed using The Cancer Genome Atlas database. Moreover, to elucidate the role of USP5 in bladder cancer, USP5 overexpression and knockdown cell lines were established using T24 cells. Cell viability, proliferation and migration were assessed using Cell Counting Kit-8, Transwell and scratch assays, respectively. Cyclohexanamide was used to evaluate the effect of USP5 expression on Snail family zinc finger 2 (SLUG) stability. Immunoprecipitation and immunofluorescence co-localization were utilized to probe the interaction between USP5 and SLUG. Changes in mRNA and protein levels were assessed using reverse transcription-quantitative PCR and western blotting, respectively. The results revealed that patients with bladder cancer with high USP5 expression had significantly shorter survival (P<0.05) and a higher clinicopathologic stage (P<0.05) than those with low USP5 expression. T24 cells overexpressing USP5 demonstrated significantly increased proliferation (P<0.05), invasion (P<0.05) and expression of epithelial-mesenchymal transition markers (P<0.05); whereas T24 cells with knocked-down USP5 expression revealed significantly reduced proliferation (P<0.05), invasion (P<0.05) and epithelial-mesenchymal transition markers (P<0.05). Immunoprecipitation experiments demonstrated the binding of USP5 to SLUG in bladder cancer cells, with further analysis revealing that USP5 upregulated protein levels of SLUG by inhibiting its ubiquitination. Furthermore, the treatment of bladder cancer cells with Degrasyn, a USP5 inhibitor, was associated with a significant inhibition of the proliferation (P<0.05) and invasion (P<0.05) of T24 cells. In conclusion, the findings of the present study underscore the role of USP5 in promoting the malignant progression of bladder cancer through the stabilization of SLUG. Targeting USP5 holds promise as a strategy for inhibiting bladder cancer progression.

Unraveling the Mechanism of Action of Ubiquitin-Specific Protease 5 and Its Inhibitors in Tumors

Ubiquitin-specific protease 5 (USP5), a member of the ubiquitin-specific proteases (USPs) family, functions by specifically removing ubiquitin chains from target proteins for stabilization and degrading unbound polyubiquitin chains to maintain a steady-state monoubiquitin pool. Ubiquitin-specific protease 5 regulates various cellular activities, including DNA double-strand break repair, transmission of neuropathic and inflammatory pain signals, immune response, and tumor cell proliferation. Furthermore, USP5 is involved in the development of multiple tumors such as liver, lung, pancreatic, and breast cancers as well as melanoma. Downstream regulatory mechanisms associated with USP5 are complex and diverse. Ubiquitin-specific protease 5 has been revealed as an emerging target for tumor treatment. This study has introduced some molecules upstream to control the expression of USP5 at the levels of transcription, translation, and post-translation. Furthermore, the study incorporated inhibitors known to be associated with USP5, including partially selective deubiquitinase (DUB) inhibitors such as WP1130, EOAI3402143, vialinin A, and chalcone derivatives. It also included the ubiquitin-activating enzyme E1 inhibitor, PYR-41. These small molecule inhibitors impact the occurrence and development of various tumors. Therefore, this article comprehensively reviews the pivotal role of USP5 in different signaling pathways during tumor progression and resumes the progress made in developing USP5 inhibitors, providing a theoretical foundation for their clinical translation.

USP33 facilitates the ovarian cancer progression via deubiquitinating and stabilizing CBX2

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

USP18 Is Associated with PD-L1 Antitumor Immunity and Improved Prognosis in Colorectal Cancer

BACKGROUND

Compared with conventional chemotherapy and targeted therapy, immunotherapy has improved the treatment outlook for a variety of solid tumors, including lung cancer, colorectal cancer (CRC), and melanoma. However, it is effective only in certain patients, necessitating the search for alternative strategies to targeted immunotherapy. The deubiquitinating enzyme USP18 is known to play an important role in various aspects of the immune response, but its role in tumor immunity in CRC remains unclear.

METHODS

In this study, multiple online datasets were used to systematically analyze the expression, prognosis, and immunomodulatory role of USP18 in CRC. The effect of USP18 on CRC was assessed via shRNA-mediated knockdown of USP18 expression in combination with CCK-8 and colony formation assays. Finally, molecular docking analysis of USP18/ISG15 and programmed death-ligand 1 (PD-L1) was performed via HDOCK, and an ELISA was used to verify the potential of USP18 to regulate PD-L1.

RESULTS

Our study revealed that USP18 expression was significantly elevated in CRC patients and closely related to clinicopathological characteristics. The experimental data indicated that silencing USP18 significantly promoted the proliferation and population-dependent growth of CRC cells. In addition, high USP18 expression was positively correlated with the CRC survival rate and closely associated with tumor-infiltrating CD8+ T cells and natural killer (NK) cells. Interestingly, USP18 was correlated with the expression of various chemokines and immune checkpoint genes. The results of molecular docking simulations suggest that USP18 may act as a novel regulator of PD-L1 and that its deficiency may potentiate the antitumor immune response to PD-L1 blockade immunotherapy in CRC.

CONCLUSIONS

In summary, USP18 shows great promise for research and clinical application as a potential target for CRC immunotherapy.

Enhancing cancer immunotherapy: Nanotechnology-mediated immunotherapy overcoming immunosuppression

Immunotherapy is an important cancer treatment method that offers hope for curing cancer patients. While immunotherapy has achieved initial success, a major obstacle to its widespread adoption is the inability to benefit the majority of patients. The success or failure of immunotherapy is closely linked to the tumor's immune microenvironment. Recently, there has been significant attention on strategies to regulate the tumor immune microenvironment in order to stimulate anti-tumor immune responses in cancer immunotherapy. The distinctive physical properties and design flexibility of nanomedicines have been extensively utilized to target immune cells (including tumor-associated macrophages (TAMs), T cells, myeloid-derived suppressor cells (MDSCs), and tumor-associated fibroblasts (TAFs)), offering promising advancements in cancer immunotherapy. In this article, we have reviewed treatment strategies aimed at targeting various immune cells to regulate the tumor immune microenvironment. The focus is on cancer immunotherapy models that are based on nanomedicines, with the goal of inducing or enhancing anti-tumor immune responses to improve immunotherapy. It is worth noting that combining cancer immunotherapy with other treatments, such as chemotherapy, radiotherapy, and photodynamic therapy, can maximize the therapeutic effects. Finally, we have identified the challenges that nanotechnology-mediated immunotherapy needs to overcome in order to design more effective nanosystems.

Ubiquitin modification in the regulation of tumor immunotherapy resistance mechanisms and potential therapeutic targets

Although immune checkpoint-based cancer immunotherapy has shown significant efficacy in various cancers, resistance still limits its therapeutic effects. Ubiquitination modification is a mechanism that adds different types of ubiquitin chains to proteins, mediating protein degradation or altering their function, thereby affecting cellular signal transduction. Increasing evidence suggests that ubiquitination modification plays a crucial role in regulating the mechanisms of resistance to cancer immunotherapy. Drugs targeting ubiquitination modification pathways have been shown to inhibit tumor progression or enhance the efficacy of cancer immunotherapy. This review elaborates on the mechanisms by which tumor cells, immune cells, and the tumor microenvironment mediate resistance to cancer immunotherapy and the details of how ubiquitination modification regulates these mechanisms, providing a foundation for enhancing the efficacy of cancer immunotherapy by intervening in ubiquitination modification.

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

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

Deubiquitinating enzymes: potential regulators of the tumor microenvironment and implications for immune evasion

Ubiquitination and deubiquitination are important forms of posttranslational modification that govern protein homeostasis. Deubiquitinating enzymes (DUBs), a protein superfamily consisting of more than 100 members, deconjugate ubiquitin chains from client proteins to regulate cellular homeostasis. However, the dysregulation of DUBs is reportedly associated with several diseases, including cancer. The tumor microenvironment (TME) is a highly complex entity comprising diverse noncancerous cells (e.g., immune cells and stromal cells) and the extracellular matrix (ECM). Since TME heterogeneity is closely related to tumorigenesis and immune evasion, targeting TME components has recently been considered an attractive therapeutic strategy for restoring antitumor immunity. Emerging studies have revealed the involvement of DUBs in immune modulation within the TME, including the regulation of immune checkpoints and immunocyte infiltration and function, which renders DUBs promising for potent cancer immunotherapy. Nevertheless, the roles of DUBs in the crosstalk between tumors and their surrounding components have not been comprehensively reviewed. In this review, we discuss the involvement of DUBs in the dynamic interplay between tumors, immune cells, and stromal cells and illustrate how dysregulated DUBs facilitate immune evasion and promote tumor progression. We also summarize potential small molecules that target DUBs to alleviate immunosuppression and suppress tumorigenesis. Finally, we discuss the prospects and challenges regarding the targeting of DUBs in cancer immunotherapeutics and several urgent problems that warrant further investigation.

Drug resistance mechanisms and treatment strategies mediated by Ubiquitin-Specific Proteases (USPs) in cancers: new directions and therapeutic options

Drug resistance represents a significant obstacle in cancer treatment, underscoring the need for the discovery of novel therapeutic targets. Ubiquitin-specific proteases (USPs), a subclass of deubiquitinating enzymes, play a pivotal role in protein deubiquitination. As scientific research advances, USPs have been recognized as key regulators of drug resistance across a spectrum of treatment modalities, including chemotherapy, targeted therapy, immunotherapy, and radiotherapy. This comprehensive review examines the complex relationship between USPs and drug resistance mechanisms, focusing on specific treatment strategies and highlighting the influence of USPs on DNA damage repair, apoptosis, characteristics of cancer stem cells, immune evasion, and other crucial biological functions. Additionally, the review highlights the potential clinical significance of USP inhibitors as a means to counter drug resistance in cancer treatment. By inhibiting particular USP, cancer cells can become more susceptible to a variety of anti-cancer drugs. The integration of USP inhibitors with current anti-cancer therapies offers a promising strategy to circumvent drug resistance. Therefore, this review emphasizes the importance of USPs as viable therapeutic targets and offers insight into fruitful directions for future research and drug development. Targeting USPs presents an effective method to combat drug resistance across various cancer types, leading to enhanced treatment strategies and better patient outcomes.

PD-1 regulation in immune homeostasis and immunotherapy

Harnessing the programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) axis is pivotal in autoimmunity and cancer immunotherapy. PD-1 receptors on immune cells engage with one of its ligands, PD-L1 or PD-L2, expressed on antigen-presenting cells or tumor cells, driving T-cell dysfunction and tumor immune escape. Thus, targeting PD-1/PD-L1 revitalizes cytotoxic T cells for cancer elimination. However, a majority of cancer patients don't respond to PD-1/PD-L1 blockade, and the underlying mechanisms remain partially understood. Recent studies have revealed that PD-1 expression levels or modifications impact the effectiveness of anti-PD-1/PD-L1 treatments. Therefore, understanding the molecular mechanisms governing PD-1 expression and modifications is crucial for innovating therapeutic strategies to enhance the efficacy of PD-1/PD-L1 inhibition. This article presents a comprehensive overview of advancements in PD-1 regulation and highlights their potential in modulating immune homeostasis and cancer immunotherapy, aiming to refine clinical outcomes.

Emerging therapeutic frontiers in cancer: insights into posttranslational modifications of PD-1/PD-L1 and regulatory pathways

The interaction between programmed cell death ligand 1 (PD-L1), which is expressed on the surface of tumor cells, and programmed cell death 1 (PD-1), which is expressed on T cells, impedes the effective activation of tumor antigen-specific T cells, resulting in the evasion of tumor cells from immune-mediated killing. Blocking the PD-1/PD-L1 signaling pathway has been shown to be effective in preventing tumor immune evasion. PD-1/PD-L1 blocking antibodies have garnered significant attention in recent years within the field of tumor treatments, given the aforementioned mechanism. Furthermore, clinical research has substantiated the efficacy and safety of this immunotherapy across various tumors, offering renewed optimism for patients. However, challenges persist in anti-PD-1/PD-L1 therapies, marked by limited indications and the emergence of drug resistance. Consequently, identifying additional regulatory pathways and molecules associated with PD-1/PD-L1 and implementing judicious combined treatments are imperative for addressing the intricacies of tumor immune mechanisms. This review briefly outlines the structure of the PD-1/PD-L1 molecule, emphasizing the posttranslational modification regulatory mechanisms and related targets. Additionally, a comprehensive overview on the clinical research landscape concerning PD-1/PD-L1 post-translational modifications combined with PD-1/PD-L1 blocking antibodies to enhance outcomes for a broader spectrum of patients is presented based on foundational research.

UFL1 ablation in T cells suppresses PD-1 UFMylation to enhance anti-tumor immunity

UFMylation is an emerging ubiquitin-like post-translational modification that regulates various biological processes. Dysregulation of the UFMylation pathway leads to human diseases, including cancers. However, the physiological role of UFMylation in T cells remains unclear. Here, we report that mice with conditional knockout (cKO) Ufl1, a UFMylation E3 ligase, in T cells exhibit effective tumor control. Single-cell RNA sequencing analysis shows that tumor-infiltrating cytotoxic CD8+ T cells are increased in Ufl1 cKO mice. Mechanistically, UFL1 promotes PD-1 UFMylation to antagonize PD-1 ubiquitination and degradation. Furthermore, AMPK phosphorylates UFL1 at Thr536, disrupting PD-1 UFMylation to trigger its degradation. Of note, UFL1 ablation in T cells reduces PD-1 UFMylation, subsequently destabilizing PD-1 and enhancing CD8+ T cell activation. Thus, Ufl1 cKO mice bearing tumors have a better response to anti-CTLA-4 immunotherapy. Collectively, our findings uncover a crucial role of UFMylation in T cells and highlight UFL1 as a potential target for cancer treatment.

Post-translational Modification of PD-1: Potential Targets for Cancer Immunotherapy

Activation of effector T cells leads to upregulation of PD-1, which can inhibit T-cell activity following engagement with its ligand PD-L1. Post-translational modifications (PTM), including glycosylation, phosphorylation, ubiquitination, and palmitoylation, play a significant role in regulating PD-1 protein stability, localization, and interprotein interactions. Targeting PTM of PD-1 in T cells has emerged as a potential strategy to overcome PD-1-mediated immunosuppression in cancer and enhances antitumor immunity. The regulatory signaling pathways that induce PTM of PD-1 can be suppressed with small-molecule inhibitors, and mAbs can directly target PD-1 PTMs. Preliminary outcomes from exploratory studies suggest that focusing on the PTM of PD-1 has strong therapeutic potential and can enhance the response to anti-PD-1.

KRAS4A and KRAS4B in liquid biopsy of metastatic lung adenocarcinoma patients treated with Pembrolizumab or chemotherapy plus Pembrolizumab

KRAS is involved in the stability and expression of PD-L1. We investigated the expression of circulating mRNA (cmRNA) of KRAS4A and KRAS4B and the possible impact on progression-free survival (PFS) of patients with metastatic lung adenocarcinoma treated with immunotherapy. Patients without driver mutations undergoing Pembrolizumab (P) or P plus chemotherapy (PC) were prospectively accrued for liquid biopsy analysis of KRAS4A, KRAS4B, and PD-L1 cmRNA. Both KRAS isoforms were also studied for association with PD-L1 cmRNA. Of 56 patients, 28 received P and 28 PC. Patients with high levels of both KRAS isoforms showed significantly better PFS. The median PFS for KRAS4A was 29 months (95% CI 22-29 months) and KRAS4B 24 months (95% CI 13-29 months), respectively. The median PFS of patients with low levels of both isoforms was 12 months (95% CI 6-15 months for KRAS4A and 95% CI 5-20 months for KRAS4B). High KRAS4A retained a significant positive association with PFS in the multivariate model. An exploratory analysis in treatment subgroups found a positive association between high KRAS4A and KRAS4B with PFS in patients treated with P. PD-L1 cmRNA was significantly higher in patients with high KRAS isoforms levels and this effect was pronounced for high KRAS4A carriers. KRAS4A deserves further investigation as a potential marker for defining patients who may benefit the most from immune checkpoint inhibitors therapy and improving personalized cancer immunotherapeutic strategies.

Ultrasound-Induced Gold Nanoparticle United with Acoustic Reprogramming of Macrophages for Enhanced Cancer Therapy

Sonodynamic therapy (SDT) has considerable potential in cancer treatment and exhibits high tissue penetration with minimal damage to healthy tissues. The efficiency of SDT is constrained by the complex immunological environment and tumor treatment resistance. Herein, a specific acoustic-actuated tumor-targeted nanomachine is proposed to generate mechanical damage to lysosomes for cancer SDT. The hybrid nanomachine was assembled with gold nanoparticles (GNPs) as the core and encapsulated with macrophage exosomes modified by AS1411 aptamers (GNP@EXO-APs) to optimize the pharmacokinetics and tumor aggregation. GNP@EXO-APs could be specifically transferred to the lysosomes of tumor cells. After induction with ultrasound, GNP@EXO-APs generated strong mechanical stress to produce lysosomal-dependent cell death in cancer cells. Notably, tumor-associated macrophages were reprogrammed in the ultrasound environment to an antitumor phenotype. Enhanced mechanical destruction via GNP@EXO-APs and immunotherapy of cancer cells were verified both in vitro and in vivo under SDT. This study provides a new direction for inside-out killing effects on tumor cells for cancer treatment.

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.