USP8 is a Novel Therapeutic Target in Melanoma Through Regulating Receptor Tyrosine Kinase Levels

Overexpression of USP8 inhibits inflammation and ferroptosis in chronic obstructive pulmonary disease by regulating the OTUB1/SLC7A11 signaling pathway

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a familiar disease, and owns high morbidity and mortality, which critically damages the health of patients. Ubiquitin-specific peptidase 8 (USP8) is a pivotal protein to join in the regulation of some diseases. In a previous report, it was determined that USP8 expression is down-regulated in LPS-treated BEAS-2B cells, and USP8 restrains inflammatory response and accelerates cell viability. However, the regulatory roles of USP8 on ferroptosis in COPD are rarely reported, and the associated molecular mechanisms keep vague.

OBJECTIVE

To investigate the regulatory functions of USP8 in COPD progression.

MATERIAL AND METHODS

The lung functions were measured through the Buxco Fine Pointe Series Whole Body Plethysmography (WBP). The Fe level was tested through the Fe assay kit. The protein expressions were assessed through western blot. The levels of tumor necrosis -factor-α, interleukin 6, and interleukin 8 were evaluated through enzyme-linked immunosorbent serologic assay. Cell viability was tested through CCK-8 assay.

RESULTS

In this work, it was discovered that overexpression of USP8 improved lung function in COPD mice. In addition, overexpression of USP8 repressed ferroptosis by regulating glutathione peroxidase 4 and acyl-CoA synthetase long-chain family 4 expressions in COPD mice. Overexpression of USP8 suppressed inflammation in COPD mice. Furthermore, overexpression of USP8 suppressed ferroptosis in COPD cell model. At last, it was verified that overexpression of USP8 accelerated ubiquitin aldehyde-binding protein 1 (OTUB1)/solute carrier family 7 member 11 (SLC7A11) pathway.

CONCLUSION

This study manifested that overexpression of USP8 restrained inflammation and ferroptosis in COPD by regulating the OTUB1/SLC7A11 signaling pathway. This discovery hinted that USP8 could be a potential target for COPD treatment.

A Proteomics Approach Identifies RREB1 as a Crucial Molecular Target of Imidazo-Pyrazole Treatment in SKMEL-28 Melanoma Cells

Cutaneous melanoma is the most dangerous and deadly form of human skin malignancy. Despite its rarity, it accounts for a staggering 80% of deaths attributed to cutaneous cancers overall. Moreover, its final stages often exhibit resistance to drug treatments, resulting in unfavorable outcomes. Hence, ensuring access to novel and improved chemotherapeutic agents is imperative for patients grappling with this severe ailment. Pyrazole and its fused systems derived thereof are heteroaromatic moieties widely employed in medicinal chemistry to develop effective drugs for various therapeutic areas, including inflammation, pain, oxidation, pathogens, depression, and fever. In a previous study, we described the biochemical properties of a newly synthesized group of imidazo-pyrazole compounds. In this paper, to improve our knowledge of the pharmacological properties of these molecules, we conduct a differential proteomic analysis on a human melanoma cell line treated with one of these imidazo-pyrazole derivatives. Our results detail the changes to the SKMEL-28 cell line proteome induced by 24, 48, and 72 h of 3e imidazo-pyrazole treatment. Notably, we highlight the down-regulation of the Ras-responsive element binding protein 1 (RREB1), a member of the zinc finger transcription factors family involved in the tumorigenesis of melanoma. RREB1 is a downstream element of the MAPK pathway, and its activation is mediated by ERK1/2 through phosphorylation.

Targeting USP8 Inhibits O-GlcNAcylation of SLC7A11 to Promote Ferroptosis of Hepatocellular Carcinoma via Stabilization of OGT

Hepatocellular carcinoma (HCC) is a lethal and aggressive human malignancy. The present study examins the anti-tumor effects of deubiquitylating enzymes (DUB) inhibitors in HCC. It is found that the inhibitor of ubiquitin specific peptidase 8 (USP8) and DUB-IN-3 shows the most effective anti-cancer responses. Targeting USP8 inhibits the proliferation of HCC and induces cell ferroptosis. In vivo xenograft and metastasis experiments indicate that inhibition of USP8 suppresses tumor growth and lung metastasis. DUB-IN-3 treatment or USP8 depletion decrease intracellular cystine levels and glutathione biosynthesis while increasing the accumulation of reactive oxygen species (ROS). Mechanistical studies reveal that USP8 stabilizes O-GlcNAc transferase (OGT) via inhibiting K48-specific poly-ubiquitination process on OGT protein at K117 site, and STE20-like kinase (SLK)-mediated S716 phosphorylation of USP8 is required for the interaction with OGT. Most importantly, OGT O-GlcNAcylates solute carrier family 7, member 11 (SLC7A11) at Ser26 in HCC cells, which is essential for SLC7A11 to import the cystine from the extracellular environment. Collectively, this study demonstrates that pharmacological inhibition or knockout of USP8 can inhibit the progression of HCC and induce ferroptosis via decreasing the stability of OGT, which imposes a great challenge that targeting of USP8 is a potential approach for HCC treatment.

USP8 inhibitor-induced DNA damage activates cell cycle arrest, apoptosis, and autophagy in esophageal squamous cell carcinoma

Increasing evidence suggests that targeting ubiquitin-specific peptidase 8 (USP8) serves as an attractive anti-cancer strategy. However, the role of USP8 inhibitor, DUB-IN-1, in esophageal squamous cell carcinoma (ESCC) cells still needs to be explored. Here, immunohistochemistry was employed to examine the expression of USP8 in ESCC tissues. Cell Counting Kit-8 (CCK-8) was used to evaluate cell proliferation ability, and propidium iodide (PI) was selected to test the effect of DUB-IN-1 on cell cycle. AnnexinV-FITC/PI staining and the activity of caspase 3 were detedcted to evaluate apoptosis. Transmission electron microscope, microtubule-associated protein 1 light-chain 3 (LC3) expression, and acridine orange (AO) staining were selected to check if there was autophagy. Comet assay and γ-H2AX immunofluorescence was used to monitor DNA damage. Rescue experiment was used to determine the key role of of p53 in cell cycle, apoptosis, and autophagy. Results revealed that the leve of USP8 was higher in ESCC tissues than that in tissues adjacent to carcinoma. DUB-IN-1, an USP8 inhibitor, caused DNA damage, led to G2/M phase block by p53-p21 axis, and triggered apoptosis by regulating the p53 target proteins including Bax, Noxa, and Puma. Besides, DUB-IN-1 could stimulate autophagy through p53-dependent adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) activation. Taken together, this study revealed the cytotoxic effects and the mechanism of DUB-IN-1, which indicated that DUB-IN-1 may be a novel inhibitor targeting USP8 that can kill ESCC cells. USP8 inhibitor, DUB-IN-1, treatment could inhibit esophageal squamous cell carcinoma cell growth and induce G2/M cell cycle arrest, apoptosis, and autophagy by DNA damage-induced p53 activation. DUB-IN-1 treatment led to G2/M cell cycle arrest by upregulating the protein level of p21 and triggered apoptosis by modulating the p53 target proteins including Bax, Noxa, and Puma. Meanwhile, DUB-IN-1 treatment stimulated protective autophagy through p53-dependent AMPK activation. Collectively, these findings suggested that DNA damage-triggered p53 activation, p53-Puma/Noxa/Bax, p53-p21, and p53-AMPK pathways were all involved in the effect of DUB-IN-1.

USP8 positively regulates hepatocellular carcinoma tumorigenesis and confers ferroptosis resistance through β-catenin stabilization

Hepatocellular carcinoma (HCC) is the most common type of primary hepatic carcinoma, which is a growing public health problem worldwide. One of the main genetic alterations in HCC is the deregulated Wnt/β-catenin signaling, activation of β-catenin is associated with the progression of HCC. In the present study, we aimed to identify novel modulators in controlling β-catenin ubiquitination and stability. USP8 was overexpressed in HCC tissues and correlated with β-catenin protein level. High expression of USP8 indicated poor prognosis of HCC patients. USP8 depletion significantly decreased β-catenin protein level, β-catenin target genes expression and TOP-luciferase activity in HCC cells. Further mechanistic study revealed that the USP domain of USP8 interacted with the ARM domain of β-catenin. USP8 stabilized β-catenin protein via inhibiting K48-specific poly-ubiquitination process on β-catenin protein. In addition, USP8 depletion inhibited the proliferation, invasion and stemness of HCC cells and conferred ferroptosis resistance, which effects could be further rescued by β-catenin overexpression. In addition, the USP8 inhibitor DUB-IN-3 inhibited the aggressive phenotype and promoted ferroptosis of HCC cells through degradation of β-catenin. Thus, our study demonstrated that USP8 activated the Wnt/beta-catenin signaling through a post-translational mechanism of β-catenin. High expression of USP8 promoted the progression and inhibited ferroptosis of HCC. Targeting the USP8 may serve as a promising strategy for patients with HCC.

Pharmacological inhibition of the ubiquitin-specific protease 8 effectively suppresses glioblastoma cell growth

Glioblastoma (GBM) is a malignant brain tumor. The purpose of this study is to estimate the potential effects and underlying mechanisms of a ubiquitin-specific protease 8 (USP8) small-molecule inhibitor on the phenotypic characteristics of GBM cells. The growth, migration, invasion, and stemness of GBM LN229 and T98G cells were evaluated by conducting cell proliferation, colony formation, wound healing, transwell, Ki-67 staining, spheroid formation, and ionizing radiation assays, and the results collectively showed the suppressive effects of USP8 inhibition on GBM cells. Furthermore, transcriptomic profiling of GBM cells treated with the USP8 inhibitor deubiquitinase (DUB)-IN-1 revealed significantly altered mRNA expression induced by pharmacological USP8 inhibition, from which we confirmed downregulated Aurora kinase A (AURKA) protein levels using immunoblotting assays. Our findings indicated that the proliferation, invasion, and stemness of LN229 and T98G cells were markedly suppressed by USP8 inhibition. Pharmacological USP8 suppression elicits multiple tumor-inhibitory effects, likely through dysregulating various mRNA expression events, including that of the key cell cycle regulator and oncogenic protein AURKA. Therefore, our observations corroborate the GBM-supportive roles of USP8 and suggest pharmacological USP8 inhibition is a viable therapeutic approach to target GBM. The purpose of this study was to investigate the effect and mechanism of action of the USP8 inhibitor DUB-IN-1 on GBM.

Catechol-O-methyl transferase suppresses cell invasion and interplays with MET signaling in estrogen dependent breast cancer

Catechol-O-methyl transferase (COMT) is involved in detoxification of catechol estrogens, playing cancer-protective role in cells producing or utilizing estrogen. Moreover, COMT suppressed migration potential of breast cancer (BC) cells. To delineate COMT role in metastasis of estrogen receptor (ER) dependent BC, we investigated the effect of COMT overexpression on invasion, transcriptome, proteome and interactome of MCF7 cells, a luminal A BC model, stably transduced with lentiviral vector carrying COMT gene (MCF7-COMT). 2D and 3D assays revealed that COMT overexpression associates with decreased cell invasion (p < 0.0001 for Transwell assay, p < 0.05 for spheroid formation). RNA-Seq and LC-DIA-MS/MS proteomics identified genes associated with invasion (FTO, PIR, TACSTD2, ANXA3, KRT80, S100P, PREX1, CLEC3A, LCP1) being downregulated in MCF7-COMT cells, while genes associated with less aggressive phenotype (RBPMS, ROBO2, SELENBP, EPB41L2) were upregulated both at transcript (|log2FC|> 1, adj. p < 0.05) and protein (|log2FC|> 0.58, q < 0.05) levels. Importantly, proteins driving MET signaling were less abundant in COMT overexpressing cells, and pull-down confirmed interaction between COMT and Kunitz-type protease inhibitor 2 (SPINT2), a negative regulator of MET (log2FC = 5.10, q = 1.04-7). In conclusion, COMT may act as tumor suppressor in ER dependent BC not only by detoxification of catechol estrogens but also by suppressing cell invasion and interplay with MET pathway.

Discovery of Potent Small-Molecule USP8 Inhibitors for the Treatment of Breast Cancer through Regulating ERα Expression

Ubiquitin-specific protease 8 (USP8), belonging to the deubiquitinase family, has been implicated to be closely related to the occurrence of many malignant tumors, but only a few USP8-targeting inhibitors have been reported to date. In this study, we present virtual screening to discover novel hit candidates that inhibit the catalytic activity of USP8. Exploration of the structure-activity relationship led to the identification of compound DC-U4106, which binds to USP8 with a K_D value of 4.7 μM and is selective over USP2 and USP7. Western blotting and immunoprecipitation showed that DC-U4106 could target the ubiquitin pathway and facilitate the degradation of ERα. In a xenograft tumor model, DC-U4106 also significantly inhibited tumor growth with minimal toxicity. Overall, our findings suggest that DC-U4106 is a promising drug candidate and targeting the USP8-ERα complex could be a new approach to treat ER-positive or drug-resistant breast cancer.

Canine Oral Melanoma Genomic and Transcriptomic Study Defines Two Molecular Subgroups with Different Therapeutical Targets

Simple Summary

In humans, mucosal melanoma (MM) is a rare and aggressive cancer. The canine model is frequently and spontaneously affected by MM, thus facilitating the collection of samples and the study of its genetic bases. Thanks to an integrative genomic and transcriptomic analysis of 32 canine MM samples, we identified two molecular subgroups of MM with a different microenvironment and structural variant (SV) content. We demonstrated that SVs are associated with recurrently amplified regions, and identified new candidate oncogenes (TRPM7, GABPB1, and SPPL2A) for MM. Our findings suggest the existence of two MM molecular subgroups that could benefit from dedicated therapies, such as immune checkpoint inhibitors or targeted therapies, for both human and veterinary medicine.

Abstract

Mucosal melanoma (MM) is a rare, aggressive clinical cancer. Despite recent advances in genetics and treatment, the prognosis of MM remains poor. Canine MM offers a relevant spontaneous and immunocompetent model to decipher the genetic bases and explore treatments for MM. We performed an integrative genomic and transcriptomic analysis of 32 canine MM samples, which identified two molecular subgroups with a different microenvironment and structural variant (SV) content. The overexpression of genes related to the microenvironment and T-cell response was associated with tumors harboring a lower content of SVs, whereas the overexpression of pigmentation-related pathways and oncogenes, such as TERT, was associated with a high SV burden. Using whole-genome sequencing, we showed that focal amplifications characterized complex chromosomal rearrangements targeting oncogenes, such as MDM2 or CDK4, and a recurrently amplified region on canine chromosome 30. We also demonstrated that the genes TRPM7, GABPB1, and SPPL2A, located in this CFA30 region, play a role in cell proliferation, and thus, may be considered as new candidate oncogenes for human MM. Our findings suggest the existence of two MM molecular subgroups that may benefit from dedicated therapies, such as immune checkpoint inhibitors or targeted therapies, for both human and veterinary medicine.