The role of type II transmembrane serine protease-mediated signaling in cancer

Usability Evaluation of Urinary HAI-1, STMN-1 and TN-C in the Diagnosis of Bladder Cancer

Background: Proteins with different functions, such as Hepatocyte growth factor activator inhibitor type 1 (HAI-1), Stathmin 1 (STMN-1), and Tenascin C (TN-C), whose activity has been observed in various types of cancers, inspired our study in bladder cancer (BC) patients. The aim of the study was to evaluate selected parameters and their combinations in the diagnosis of BC. The study took into account the degree of invasiveness and malignancy of BC. Based on the analysis of the Receiver Operating Characteristic Curve (ROC), the diagnostic value of single parameters and their combinations as potential indicators of BC was assessed. Patients and Methods: The research material consisted of urine samples from patients with BC, and urine samples from a control group without urological diseases. The concentrations of the examined parameters were measured using an immunoenzymatic method. Results: Statistically significant higher concentrations of HAI-1 (p ≤ 0.001), STMN-1 (≤0.001) and TN-C (0.002) were found in the patients with BC compared to the control group. Strong relationships were shown between these parameters. ROC analyses showed that the best single parameter for detecting BC is STMN-1, and in the combination of HAI-1+STMN-1. The highest diagnostic value was obtained for the combination of HAI-1+STMN-1 in the patients with high malignancy (sensitivity 82%, specificity 91%). Conclusions: Preliminary studies of parameters have shown their utility as potential markers in BC, especially of STMN-1 and combinations HAI-1+STMN-1. However, to learn more about the contribution of these parameters to the progression of bladder cancer, it would be appropriate to continue the studies.

Structural basis of TMPRSS11D specificity and autocleavage activation

Transmembrane Protease, Serine-2 (TMPRSS2) and TMPRSS11D are human proteases that enable SARS-CoV-2 and Influenza A/B virus infections, but their biochemical mechanisms for facilitating viral cell entry remain unclear. We show these proteases spontaneously and efficiently cleave their own zymogen activation motifs, activating their broader protease activity on cellular substrates. We determine TMPRSS11D co-crystal structures with a native and an engineered activation motif, revealing insights into its autocleavage activation and distinct substrate binding cleft features. Leveraging this structural data, we develop nanomolar potency peptidomimetic inhibitors of TMPRSS11D and TMPRSS2. We show that a broad serine protease inhibitor that underwent clinical trials for TMPRSS2-targeted COVID-19 therapy, nafamostat mesylate, was rapidly cleaved by TMPRSS11D and converted to low activity derivatives. In this work, we develop mechanistic insights into human protease viral tropism and highlight both the strengths and limitations of existing human serine protease inhibitors, informing future drug discovery efforts targeting these proteases.

Phases of tight junction barrier disruption during transurothelial migration of invasive urothelial cancer cells

Bladder cancer is characterised by its multifocal nature and a high recurrence, yet the underlying mechanisms of these phenomena remain only partially understood. In the present study, we aimed to investigate transurothelial invasion of urothelial cancer cells as a potential mechanism for dissemination of bladder cancer and to identify the key molecules involved in urothelial barrier disruption. Using confocal and electron microscopy, we were able to show that within a 24-hour timeframe muscle-invasive urothelial cancer cells T24 adhere to the partially differentiated normal urothelial in vitro model and initially cause localised disruption of the tight junctions between urothelial cells. Subsequently, urothelial cells separate and individual T24 cells migrate paracellularly through the urothelium. qPCR analysis identified fibroblast activation protein (FAP)/seprase as the candidate most likely to be involved in urothelial barrier disruption. In addition, treatment of T24 cells with Pefabloc resulted in the inhibition of T24 cell invasion. Our results contribute to the understanding of the mechanisms underlying transurothelial invasion of urothelial cancer cells. Among the molecules tested, FAP/sepraseis likely involved in cancer cell-induced disruption of the urothelial barrier, suggesting its potential as a therapeutic target to prevent progression and recurrence of bladder cancer.

TMPRSS4 as a prognostic biomarker after gastric cancer surgery in a multicenter retrospective study

Transmembrane protease serine 4 (TMPRSS4) is a member of the type II transmembrane serine protease family known to be upregulated in many malignancies. We previously showed that TMPRSS4 may be a prognostic biomarker and therapeutic target for gastric cancer (GC), especially in stage III. In this retrospective study conducted at 10 institutions, all 325 patients underwent R0 resection involving D2 lymph node dissection. TMPRSS4 expression was examined using immunohistochemical analysis. TMPRSS4 expression was upregulated in 44.9% of participants. The 5-year overall survival (OS) of the TMPRSS4-positive group was significantly lower than that of the TMPRSS4-negative group (62.4% vs. 76.4%, respectively; p = 0.0149). Univariate analysis revealed that TMPRSS4 upregulation, tumor size, deeper tumor invasion, lymph node metastasis (N), lymphatic invasion, and tumor stage were significant prognostic factors for OS. Multivariate analysis revealed that N and TMPRSS4 upregulation were significant prognostic factors for OS. The 5-year OS rate was examined in two patient groups: the group with the receiver operating characteristic curve cut-off value ≥ 45% for TS-1 (cancer drug formulation) oral dosage and the group with TS-1 dosage cut-off value < 45%. For the patients in the TS-1 dosage ≥ 45% group, there were significant differences in OS between the TMPRSS4-positive and -negative groups (p = 0.0284): the 5-year OS rates of TMPRSS4-positive and -negative groups were 65.2% and 79.2%, respectively. Our findings suggest that TMPRSS4 overexpression is a useful biomarker for GC, and that an anti-TMPRSS4 antibody may have potential as a novel therapeutic agent.

Loss of tumor cell surface hepatocyte growth factor activator inhibitor-1 predicts worse prognosis in esophageal squamous cell carcinoma

Hepatocyte growth factor activator inhibitor-1 (HAI-1) is an epithelial type-1 transmembrane protease inhibitor that regulates the pericellular activities of hepatocyte growth factor activator and type-2 transmembrane serine proteases. It is strongly expressed in the stratified squamous epithelium and functions on the cell surface. We previously reported that the cell surface immunoreactivity of HAI-1 was reduced at the invasion front of oral squamous cell carcinoma. In this study, we investigate the relationship between cell surface HAI-1 (csHAI-1) and prognosis of esophageal squamous cell carcinoma (ESCC) after surgery. The effect of HAI-1 knockdown on cultured ESCC cells was also analyzed in vitro. HAI-1 exhibited distinct cell surface immunoreactivity in normal esophageal epithelium. In contrast, alterations in HAI-1 immunoreactivity were frequent in cancer cells, which exhibited aberrant intracytoplasmic localization and decreased cell surface immunoreactivity. The preservation of csHAI-1 immunoreactivity was a sign of a well-differentiated phenotype of ESCC cells. The decreased csHAI-1 was associated with shorter overall survival (OS) and disease-free survival (DFS) in the patients. In 55 cases of early (T1) ESCC cases, decreased csHAI-1 also predicted poor OS and DFS. The loss of HAI-1 enhanced migration and invasion of ESCC cells in vitro. These results suggest that the decreased cell surface immunoreactivity of HAI-1 is associated with a less differentiated phenotype and worse prognosis in ESCC. The cell surface-localized HAI-1 may serve as a promising marker for predicting recurrence and prognosis of ESCC.

COVID-19 and Carcinogenesis: Exploring the Hidden Links

The COVID-19 pandemic caused by the SARS-CoV-2 virus has been studied predominantly in terms of its immediate respiratory and systemic effects. However, emerging evidence suggests possible long-term effects, including its role in carcinogenesis. This comprehensive review explores the complex relationship between COVID-19 and cancer development, focusing on immune dysregulation, chronic inflammation, genetic and epigenetic alterations, and the impact of therapeutic interventions. We also focused on the molecular mechanisms by which SARS-CoV-2 may facilitate cancer progression, including the roles of angiotensin-converting enzyme 2 (ACE2), transmembrane serine protease 2 (TMPRSS2), and FURIN. Additionally, we examined the possible carcinogenic effects of long-term COVID-19 treatments and the interaction between co-infections and cancer risk. Our findings highlight the need for increased cancer surveillance in COVID-19 survivors. In the post-COVID-19 period, it can be thought that inflammation associated with excessive cytokine release, especially interleukin-6, genetic and epigenetic changes, and co-infections with oncogenic viruses such as Epstein-Barr virus or human papillomavirus may be effective in the development and progression of cancer. Further research is needed to explain the mechanisms underlying this relationship.

Quercetin and taxifolin inhibits TMPRSS2 activity and its interaction with EGFR in paclitaxel-resistant breast cancer cells: An in silico and in vitro study

Transmembrane protease/serine (TMPRSS2), a type II transmembrane serine protease, plays a crucial role in different stages of cancer. Recent studies have reported that the triggering epidermal growth factor receptor (EGFR) activation through protease action promotes metastasis. However, there are no reports on the interaction of TMPRSS2 with EGFR, especially in triple-negative triple negative (TNBC). The current study investigates the unexplored interaction between TMPRSS2 and EGFR, which are key partners mediating metastasis. This interaction is explored for potential targeting using quercetin (QUE) and taxifolin (TAX). TMPRSS2 expression patterns in breast cancer (BC) tissues and subtypes have been predicted, with the prognostic significance assessed using the GENT2.0 database. Validation of TMPRSS2 expression was performed in normal and TNBC tissues, including drug-resistant cell lines, utilizing GEO datasets. TMPRSS2 was further validated as a predictive biomarker for FDA-approved chemotherapeutics through transcriptomic data from BC patients. The study demonstrated the association of TMPRSS2 with EGFR through in silico analysis and validates the findings in TNBC cohorts using the TIMER2.0 web server and the TCGA dataset through C-Bioportal. Molecular docking and molecular dynamic simulation studies identified QUE and TAX as best leads targeting TMPRSS2. They inhibited cell-free TMPRSS2 activity like clinical inhibitor of TMPRSS2, Camostat mesylate. In cell-based assays focused on paclitaxel-resistant TNBC (TNBC/PR), QUE and TAX demonstrated potent inhibitory activity against extracellular and membrane-bound TMPRSS2, with low IC50 values. Furthermore, ELISA and cell-based AlphaLISA assays demonstrated that QUE and TAX inhibit the interaction of TMPRSS2 with EGFR. Additionally, QUE and TAX exhibited significant inhibition of proliferation and cell cycle accompanied by notable alterations in the morphology of TNBC/PR cells. This study provides valuable insights into potential of QUE and TAX targeting TMPRSS2 overexpressing TNBC.

Use of protease substrate specificity screening in the rational design of selective protease inhibitors with unnatural amino acids: Application to HGFA, matriptase, and hepsin

Inhibition of the proteolytic processing of hepatocyte growth factor (HGF) and macrophage stimulating protein (MSP) is an attractive approach for the drug discovery of novel anticancer therapeutics which prevent tumor progression and metastasis. Here, we utilized an improved and expanded version of positional scanning of substrate combinatorial libraries (PS-SCL) technique called HyCoSuL to optimize peptidomimetic inhibitors of the HGF/MSP activating serine proteases, HGFA, matriptase, and hepsin. These inhibitors have an electrophilic ketone serine trapping warhead and thus form a reversible covalent bond to the protease. We demonstrate that by varying the P2, P3, and P4 positions of the inhibitor with unnatural amino acids based on the protease substrate preferences learned from HyCoSuL, we can predictably modify the potency and selectivity of the inhibitor. We identified the tetrapeptide JH-1144 (8) as a single digit nM inhibitor of HGFA, matriptase and hepsin with excellent selectivity over Factor Xa and thrombin. These unnatural peptides have increased metabolic stability relative to natural peptides of similar structure. The tripeptide inhibitor PK-1-89 (2) has excellent pharmacokinetics in mice with good compound exposure out to 24 h. In addition, we obtained an X-ray structure of the inhibitor MM1132 (15) bound to matriptase revealing an interesting binding conformation useful for future inhibitor design.

Efficacy of host cell serine protease inhibitor MM3122 against SARS-CoV-2 for treatment and prevention of COVID-19

We developed a novel class of peptidomimetic inhibitors targeting several host cell human serine proteases, including transmembrane protease serine 2 (TMPRSS2), matriptase, and hepsin. TMPRSS2 is a membrane-associated protease that is highly expressed in the upper and lower respiratory tracts and is utilized by SARS-CoV-2 and other viruses to proteolytically process their glycoproteins, enabling host cell entry, replication, and dissemination of new virus particles. We have previously shown that compound MM3122 exhibited subnanomolar potency against all three proteases and displayed potent antiviral effects against SARS-CoV-2 in a cell viability assay. Herein, we demonstrate that MM3122 potently inhibits viral replication in human lung epithelial cells and is also effective against the EG.5.1 variant of SARS-CoV-2. Furthermore, we evaluated MM3122 in a mouse model of COVID-19 and demonstrated that MM3122 administered intraperitoneally (IP) before (prophylactic) or after (therapeutic) SARS-CoV-2 infection had significant protective effects against weight loss and lung congestion and reduced pathology. Amelioration of COVID-19 disease was associated with a reduction in proinflammatory cytokine and chemokine production after SARS-CoV-2 infection. Prophylactic, but not therapeutic, administration of MM3122 also reduced virus titers in the lungs of SARS-CoV-2-infected mice. Therefore, MM3122 is a promising lead candidate small-molecule drug for the treatment and prevention of infections caused by SARS-CoV-2 and other coronaviruses.

IMPORTANCE

SARS-CoV-2 and other emerging RNA coronaviruses are a present and future threat in causing widespread endemic and pandemic infection and disease. In this paper, we have shown that the novel host cell protease inhibitor, MM3122, blocks SARS-CoV-2 viral replication and is efficacious as both a prophylactic and a therapeutic drug for the treatment of COVID-19 given intraperitoneally in mice. Targeting host proteins and pathways in antiviral therapy is an underexplored area of research, but this approach promises to avoid drug resistance by the virus, which is common in current antiviral treatments.

Prodrugs as empowering tools in drug discovery and development: recent strategic applications of drug delivery solutions to mitigate challenges associated with lead compounds and drug candidates

The delivery of a drug to a specific organ or tissue at an efficacious concentration is the pharmacokinetic (PK) hallmark of promoting effective pharmacological action at a target site with an acceptable safety profile. Sub-optimal pharmaceutical or ADME profiles of drug candidates, which can often be a function of inherently poor physicochemical properties, pose significant challenges to drug discovery and development teams and may contribute to high compound attrition rates. Medicinal chemists have exploited prodrugs as an informed strategy to productively enhance the profiles of new chemical entities by optimizing the physicochemical, biopharmaceutical, and pharmacokinetic properties as well as selectively delivering a molecule to the site of action as a means of addressing a range of limitations. While discovery scientists have traditionally employed prodrugs to improve solubility and membrane permeability, the growing sophistication of prodrug technologies has enabled a significant expansion of their scope and applications as an empowering tool to mitigate a broad range of drug delivery challenges. Prodrugs have emerged as successful solutions to resolve non-linear exposure, inadequate exposure to support toxicological studies, pH-dependent absorption, high pill burden, formulation challenges, lack of feasibility of developing solid and liquid dosage forms, first-pass metabolism, high dosing frequency translating to reduced patient compliance and poor site-specific drug delivery. During the period 2012-2022, the US Food and Drug Administration (FDA) approved 50 prodrugs, which amounts to 13% of approved small molecule drugs, reflecting both the importance and success of implementing prodrug approaches in the pursuit of developing safe and effective drugs to address unmet medical needs.

Efficacy of Host Cell Serine Protease Inhibitor MM3122 against SARS-CoV-2 for Treatment and Prevention of COVID-19

We have developed a novel class of peptidomimetic inhibitors targeting several host cell human serine proteases including transmembrane protease serine 2 (TMPRSS2), matriptase and hepsin. TMPRSS2 is a membrane associated protease which is highly expressed in the upper and lower respiratory tract and is utilized by SARS-CoV-2 and other viruses to proteolytically process their glycoproteins, enabling host cell receptor binding, entry, replication, and dissemination of new virion particles. We have previously shown that compound MM3122 exhibited sub nanomolar potency against all three proteases and displayed potent antiviral effects against SARS-CoV-2 in a cell-viability assay. Herein, we demonstrate that MM3122 potently inhibits viral replication in human lung epithelial cells and is also effective against the EG.5.1 variant of SARS-CoV-2. Further, we have evaluated MM3122 in a mouse model of COVID-19 and have demonstrated that MM3122 administered intraperitoneally (IP) before (prophylactic) or after (therapeutic) SARS-CoV-2 infection had significant protective effects against weight loss and lung congestion, and reduced pathology. Amelioration of COVID-19 disease was associated with a reduction in pro-inflammatory cytokines and chemokines production after SARS-CoV-2 infection. Prophylactic, but not therapeutic, administration of MM3122 also reduced virus titers in the lungs of SARS-CoV-2 infected mice. Therefore, MM3122 is a promising lead candidate small molecule drug for the treatment and prevention of infections caused by SARS-CoV-2 and other coronaviruses.

IMPORTANCE

SARS-CoV-2 and other emerging RNA coronaviruses are a present and future threat in causing widespread endemic and pandemic infection and disease. In this paper, we have shown that the novel host-cell protease inhibitor, MM3122, blocks SARS-CoV-2 viral replication and is efficacious as both a prophylactic and therapeutic drug for the treatment of COVID-19 in mice. Targeting host proteins and pathways in antiviral therapy is an underexplored area of research but this approach promises to avoid drug resistance by the virus, which is common in current antiviral treatments.

Transmembrane serine protease 6, a novel target for inhibition of neuronal tumor growth

Transmembrane serine protease 6 (Tmprss6) has been correlated with the occurrence and progression of tumors, but any specific molecular mechanism linking the enzyme to oncogenesis has remained elusive thus far. In the present study, we found that Tmprss6 markedly inhibited mouse neuroblastoma N2a (neuro-2a) cell proliferation and tumor growth in nude mice. Tmprss6 inhibits Smad1/5/8 phosphorylation by cleaving the bone morphogenetic protein (BMP) co-receptor, hemojuvelin (HJV). Ordinarily, phosphorylated Smad1/5/8 binds to Smad4 for nuclear translocation, which stimulates the expression of hepcidin, ultimately decreasing the export of iron through ferroportin 1 (FPN1). The decrease in cellular iron levels in neuro-2a cells with elevated Tmprss6 expression limited the availability of the metal forribo nucleotide reductase activity, thereby arresting the cell cycle prior to S phase. Interestingly, Smad4 promoted nuclear translocation of activating transcription factor 3 (ATF3) to activate the p38 mitogen-activated protein kinases signaling pathway by binding to ATF3, inducing apoptosis of neuro-2a cells and inhibiting tumor growth. Disruption of ATF3 expression significantly decreased apoptosis in Tmprss6 overexpressed neuro-2a cells. Our study describes a mechanism whereby Tmprss6 regulates the cell cycle and apoptosis. Thus, we propose Tmprss6 as a candidate target for inhibiting neuronal tumor growth.

Selection of viral capsids and promoters affects the efficacy of rescue of Tmprss3-deficient cochlea

Adeno-associated virus (AAV)-mediated gene transfer has shown promise in rescuing mouse models of genetic hearing loss, but how viral capsid and promoter selection affects efficacy is poorly characterized. Here, we tested combinations of AAVs and promoters to deliver Tmprss3, mutations in which are associated with hearing loss in humans. Tmprss3tm1/tm1 mice display severe cochlear hair cell degeneration, loss of auditory brainstem responses, and delayed loss of spiral ganglion neurons. Under the ubiquitous CAG promoter and AAV-KP1 capsid, Tmprss3 overexpression caused striking cytotoxicity in vitro and in vivo and failed to rescue degeneration or dysfunction of the Tmprss3tm1/tm1 cochlea. Reducing the dosage or using AAV-DJ-CAG-Tmprss3 diminished cytotoxicity without rescue of the Tmprss3tm1/tm1 cochlea. Finally, the combination of AAV-KP1 capsid and the EF1α promoter prevented cytotoxicity and reduced hair cell degeneration, loss of spiral ganglion neurons, and improved hearing thresholds in Tmprss3tm1/tm1 mice. Together, our study illustrates toxicity of exogenous genes and factors governing rescue efficiency, and suggests that cochlear gene therapy likely requires precisely targeted transgene expression.

Serine protease PRSS56, a novel cancer-testis antigen activated by DNA hypomethylation, promotes colorectal and gastric cancer progression via PI3K/AKT axis

BACKGROUND

Cancer/testis (CT) antigens/genes are usually overexpressed in cancers and exhibit high immunogenicity, making them promising targets for immunotherapy and cancer vaccines. The role of serine protease PRSS56 in cancers remains unknown to date.

METHODS

RNA sequencing studies were performed to screen CT genes in gastric cancer (GC) and colorectal cancer (CRC) cells exposed to DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-AZA-CdR). Bioinformatics analysis was conducted to analyze the correlation between PRSS56 expression and DNA methylation. Functional experiments were performed to explore the biological function of PRSS56 in GC and CRC.

RESULTS

In this study, we identified the testis-specific serine proteases PRSS56 as a novel CT antigen. PRSS56 was frequently overexpressed in various cancers, especially in gastrointestinal cancer. PRSS56 expression was negatively associated with promoter DNA methylation level, and positively associated with gene body methylation level. PRSS56 expression was significantly activated in colorectal and gastric cancer cells exposed to DNA methyltransferase inhibitors. Importantly, our finding highlights that the decreased methylation level of the CpG site cg10242318 in the PRSS56 promoter region resulted in its overexpression in GC and CRC. Additionally, functional assays verified that PRSS56 overexpression activated PI3K-AKT signaling in GC and CRC.

CONCLUSION

Serine protease PRSS56 is a novel CT antigen that is reactivated in cancers by promoter DNA hypomethylation. PRSS56 functions oncogenic roles in GC and CRC by activating of PI3K/AKT axis. Our results presented here represent the first data on the function of the serine protease PRSS56 in cancers.

Venetoclax is a potent hepsin inhibitor that reduces the metastatic and prothrombotic phenotypes of hepsin-expressing colorectal cancer cells

Introduction: Hepsin is a type II transmembrane serine protease and its expression has been linked to greater tumorigenicity and worse prognosis in different tumors. Recently, our group demonstrated that high hepsin levels from primary tumor were associated with a higher risk of metastasis and thrombosis in localized colorectal cancer patients. This study aims to explore the molecular role of hepsin in colorectal cancer. Methods: Hepsin levels in plasma from resected and metastatic colorectal cancer patients were analyzed by ELISA. The effect of hepsin levels on cell migration, invasion, and proliferation, as well as on the activation of crucial cancer signaling pathways, was performed in vitro using colorectal cancer cells. A thrombin generation assay determined the procoagulant function of hepsin from these cells. A virtual screening of a database containing more than 2000 FDA-approved compounds was performed to screen hepsin inhibitors, and selected compounds were tested in vitro for their ability to suppress hepsin effects in colorectal cancer cells. Xenotransplantation assays were done in zebrafish larvae to study the impact of venetoclax on invasion promoted by hepsin. Results: Our results showed higher plasma hepsin levels in metastatic patients, among which, hepsin was higher in those suffering thrombosis. Hepsin overexpression increased colorectal cancer cell invasion, Erk1/2 and STAT3 phosphorylation, and thrombin generation in plasma. In addition, we identified venetoclax as a potent hepsin inhibitor that reduced the metastatic and prothrombotic phenotypes of hepsin-expressing colorectal cancer cells. Interestingly, pretreatment with Venetoclax of cells overexpressing hepsin reduced their invasiveness in vivo. Discussion: Our results demonstrate that hepsin overexpression correlates with a more aggressive and prothrombotic tumor phenotype. Likewise, they demonstrate the antitumor role of venetoclax as a hepsin inhibitor, laying the groundwork for molecular-targeted therapy for colorectal cancer.

MCAM+ brain endothelial cells contribute to neuroinflammation by recruiting pathogenic CD4+ T lymphocytes

The trafficking of autoreactive leucocytes across the blood-brain barrier endothelium is a hallmark of multiple sclerosis pathogenesis. Although the blood-brain barrier endothelium represents one of the main CNS borders to interact with the infiltrating leucocytes, its exact contribution to neuroinflammation remains understudied. Here, we show that Mcam identifies inflammatory brain endothelial cells with pro-migratory transcriptomic signature during experimental autoimmune encephalomyelitis. In addition, MCAM was preferentially upregulated on blood-brain barrier endothelial cells in multiple sclerosis lesions in situ and at experimental autoimmune encephalomyelitis disease onset by molecular MRI. In vitro and in vivo, we demonstrate that MCAM on blood-brain barrier endothelial cells contributes to experimental autoimmune encephalomyelitis development by promoting the cellular trafficking of TH1 and TH17 lymphocytes across the blood-brain barrier. Last, we showcase ST14 as an immune ligand to brain endothelial MCAM, enriched on CD4+ T lymphocytes that cross the blood-brain barrier in vitro, in vivo and in multiple sclerosis lesions as detected by flow cytometry on rapid autopsy derived brain tissue from multiple sclerosis patients. Collectively, our findings reveal that MCAM is at the centre of a pathological pathway used by brain endothelial cells to recruit pathogenic CD4+ T lymphocyte from circulation early during neuroinflammation. The therapeutic targeting of this mechanism is a promising avenue to treat multiple sclerosis.

TMPRSS4, a type II transmembrane serine protease, as a potential therapeutic target in cancer

Proteases are involved in almost all biological processes, implying their importance for both health and pathological conditions. Dysregulation of proteases is a key event in cancer. Initially, research identified their role in invasion and metastasis, but more recent studies have shown that proteases are involved in all stages of cancer development and progression, both directly through proteolytic activity and indirectly via regulation of cellular signaling and functions. Over the past two decades, a novel subfamily of serine proteases called type II transmembrane serine proteases (TTSPs) has been identified. Many TTSPs are overexpressed by a variety of tumors and are potential novel markers of tumor development and progression; these TTSPs are possible molecular targets for anticancer therapeutics. The transmembrane protease serine 4 (TMPRSS4), a member of the TTSP family, is upregulated in pancreatic, colorectal, gastric, lung, thyroid, prostate, and several other cancers; indeed, elevated expression of TMPRSS4 often correlates with poor prognosis. Based on its broad expression profile in cancer, TMPRSS4 has been the focus of attention in anticancer research. This review summarizes up-to-date information regarding the expression, regulation, and clinical relevance of TMPRSS4, as well as its role in pathological contexts, particularly in cancer. It also provides a general overview of epithelial-mesenchymal transition and TTSPs.

Protease-Responsive Potential-Tunable AIEgens for Cell Selective Imaging of TMPRSS2 and Accurate Inhibitor Screening

Transmembrane protease serine 2 (TMPRSS2) is a plasma membrane protease that activates both spike protein of coronaviruses for cell entry and oncogenic signaling pathways for tumor progression. TMPRSS2 inhibition can reduce cancer invasion and metastasis and partially prevent the entry of SARS-CoV-2 into host cells. Thus, there is an urgent need for both TMPRSS2-selective imaging and precise screening of TMPRSS2 inhibitors. Here, we report a TMPRSS2-responsive surface-potential-tunable peptide-conjugated probe (EGTP) with aggregation-induced emission (AIE) features for TMPRSS2 selective imaging and accurate inhibitor screening. The amphiphilic EGTP was constructed with tunable surface potential and responsive efficiency with TMPRSS2 and its inhibitor. The rational construction of AIE luminogens (AIEgens) with modular peptides indicated that the cleavage of EGTP led to a gradual aggregation with bright fluorescence in high TMPRSS2-expressing cells. This strategy may have value for selective detection of cancer cells, SARS-CoV-2-target cells, and screening of protease inhibitors.

Reactive Centre Loop Mutagenesis of SerpinB3 to Target TMPRSS2 and Furin: Inhibition of SARS-CoV-2 Cell Entry and Replication

The SARS-CoV-2 virus can utilize host cell proteases to facilitate cell entry, whereby the Spike (S) protein is cleaved at two specific sites to enable membrane fusion. Furin, transmembrane protease serine 2 (TMPRSS2), and cathepsin L (CatL) are the major proteases implicated, and are thus targets for anti-viral therapy. The human serpin (serine protease inhibitor) alpha-1 antitrypsin (A1AT) shows inhibitory activity for TMPRSS2, and has previously been found to suppress cell infection with SARS-CoV-2. Here, we have generated modified serpin inhibitors with increased specificity for these cellular proteases. Using SerpinB3 (SCCA-1), a cross-class inhibitor of CatL, as a scaffold, we have designed and produced reactive centre loop (RCL) variants to more specifically target both furin and TMPRSS2. Two further variants were generated by substituting the RCL P7–P1 with the spike protein S1/S2 cleavage site from either SARS-CoV-2 alpha or delta (P681R) sequences. Altered inhibitory specificity of purified recombinant proteins was verified in protease assays, with attenuated CatL inhibition and gain of furin or TMPRSS2 inhibition, as predicted, and modified serpins were shown to block S protein cleavage in vitro. Furthermore, the serpin variants were able to inhibit S-pseudoparticle entry into A549-ACE2-TMPRSS2 cells and suppress SARS-CoV-2 replication in Vero E6 cells expressing TMPRSS2. The construct designed to inhibit TMPRSS2 (B3-TMP) was most potent. It was more effective than A1AT for TMPRSS2 enzyme inhibition (with an eighteen-fold improvement in the second order inhibition rate constant) and for blocking SARS-CoV-2 viral replication. These findings advance the potential for serpin RCL mutagenesis to generate new inhibitors, and may lead to novel anti-viral biological molecules.

TMPRSS13 zymogen activation, surface localization, and shedding is regulated by proteolytic cleavage within the non-catalytic stem region

TMPRSS13 is a member of the type II transmembrane serine protease (TTSP) family. Here we characterize a novel post-translational mechanism important for TMPRSS13 function: proteolytic cleavage within the extracellular TMPRSS13 stem region located between the transmembrane domain and the first site of N-linked glycosylation at asparagine (N)-250 in the scavenger receptor cysteine rich (SRCR) domain. Importantly, the catalytic competence of TMPRSS13 is essential for stem region cleavage, suggesting an autonomous mechanism of action. Site-directed mutagenesis of the 10 basic amino acids (four arginine and six lysine residues) in this region abrogated zymogen activation and catalytic activity of TMPRSS13, as well as phosphorylation, cell surface expression, and shedding. Mutation analysis of individual arginine residues identified R223, a residue located between the low-density lipoprotein receptor class A domain and the SRCR domain, as important for stem region cleavage. Mutation of R223 causes a reduction in the aforementioned functional processing steps of TMPRSS13. These data provide further insight into the roles of different post-translational modifications as regulators of the function and localization of TMPRSS13. Additionally, the data suggest the presence of complex interconnected regulatory mechanisms that may serve to ensure the proper levels of cell-surface and pericellular TMPRSS13-mediated proteolysis under homeostatic conditions.

Structure and activity of human TMPRSS2 protease implicated in SARS-CoV-2 activation

Transmembrane protease, serine 2 (TMPRSS2) has been identified as key host cell factor for viral entry and pathogenesis of SARS-CoV-2. Specifically, TMPRSS2 proteolytically processes the SARS-CoV-2 Spike (S) protein, enabling virus-host membrane fusion and infection of the airways. We present here a recombinant production strategy for enzymatically active TMPRSS2 and characterization of its matured proteolytic activity, as well as its 1.95 Å X-ray cocrystal structure with the synthetic protease inhibitor nafamostat. Our study provides a structural basis for the potent but nonspecific inhibition by nafamostat and identifies distinguishing features of the TMPRSS2 substrate binding pocket that explain specificity. TMPRSS2 cleaved SARS-CoV-2 S protein at multiple sites, including the canonical S1/S2 cleavage site. We ranked the potency of clinical protease inhibitors with half-maximal inhibitory concentrations ranging from 1.4 nM to 120 µM and determined inhibitor mechanisms of action, providing the groundwork for drug development efforts to selectively inhibit TMPRSS2.

A Renal-Clearable Activatable Molecular Probe for Fluoro-Photacoustic and Radioactive Imaging of Cancer Biomarkers

In vivo simultaneous visualization of multiple biomarkers is critical to accurately diagnose disease and decipher fundamental processes at a certain pathological evolution, which however is rarely exploited. Herein, a multimodal activatable imaging probe (P-¹²⁵ I) is reported with activatable fluoro-photoacoustic and radioactive signal for in vivo imaging of biomarkers (i.e., hepsin and prostate-specific membrane antigen (PSMA)) associated with prostate cancer diagnosis and prognosis. P-¹²⁵ I contains a near-infrared (NIR) dye that is caged with a hepsin-cleavable peptide sequence and linked with a radiolabeled PSMA-targeted ligand (PSMAL). After systemic administration, P-¹²⁵ I actively targets the tumor site via specific recognition between PSMA and PSMAL moiety and in-situ generates of activated fluoro-photoacoustic signal after reacting with hepsin to release the free dye (uncaged state). P-¹²⁵ I achieves precisely early detection of prostate cancer and renal clearance to alleviate toxicity issues. In addition, the accumulated radioactive and activated photoacoustic signal of probe correlates well with the respective expression level of PSMA and hepsin, which provides valuable foreseeability for cancer progression and prognosis. Thus, this study presents a multimodal activatable probe for early detection and in-depth deciphering of prostate cancer.

Implication of Hepsin from Primary Tumor in the Prognosis of Colorectal Cancer Patients

Hepsin is a type II transmembrane serine protease whose deregulation promotes tumor invasion by proteolysis of the pericellular components. In colorectal cancer, the implication of hepsin is unknown. Consequently, we aimed to study the correlations between hepsin expression and different clinical-histopathological variables in 169 patients with localized colorectal cancer and 118 with metastases. Tissue microarrays were produced from samples at diagnosis of primary tumors and stained with an anti-hepsin antibody. Hepsin expression was correlated with clinical-histopathological variables by using the chi-square and Kruskal−Wallis tests, Kaplan−Meier and Aalen−Johansen estimators, and Cox and Fine and Gray multivariate models. In localized cancer patients, high-intensity hepsin staining was associated with reduced 5-year disease-free survival (p-value = 0.16). Medium and high intensity of hepsin expression versus low expression was associated with an increased risk of metastatic relapse (hazard ratio 2.83, p-value = 0.035 and hazard ratio 3.30, p-value = 0.012, respectively), being a better prognostic factor than classic histological variables. Additionally, in patients with localized tumor, 5-year thrombosis cumulative incidence increased with the increment of hepsin expression (p-value = 0.038). Medium and high intensities of hepsin with respect to low intensity were associated with an increase in thrombotic risk (hazard ratio 7.71, p-value = 0.043 and hazard ratio 9.02, p-value = 0.028, respectively). This relationship was independent of previous tumor relapse (p-value = 0.036). Among metastatic patients, low hepsin expression was associated with a low degree of tumor differentiation (p-value < 0.001) and with major metastatic dissemination (p-value = 0.023). Hepsin is a potential thrombotic and metastatic biomarker in patients with localized colorectal cancer. In metastatic patients, hepsin behaves in a paradoxical way with respect to differentiation and invasion processes.

Structure-Based Design of High-Affinity and Selective Peptidomimetic Hepsin Inhibitors

In many solid tumors, increased upregulation of transmembrane serine proteases (TTSPs) leads to an overactivation of growth factors, which promotes tumor progression. Here, we have used a combinatorial methodology to develop high-affinity tetrapeptidic inhibitors. A previous virtual screening of 8000 peptide combinations against the crystal structure of the TTSP hepsin identified a series of recognition sequences, customized for the non-prime substrate binding (P) sites of this serine protease. A combination of the top recognition sequences with an electrophilic warhead resulted in highly potent inhibitors with good selectivity against coagulation proteases factor Xa and thrombin. Structure-activity relationships of two selected compounds were further elucidated by investigation of their stability in biological fluids as well as the influence of the warhead and truncated inhibitors on the inhibitory potency. Overall, this methodology yielded compounds as selective inhibitors for potential cancer drug development, where hepsin is overexpressed.

Upregulation of the transmembrane protease serine 3 mRNA level in radioresistant colorectal cancer tissues

Aim: To investigate the clinical role of transmembrane protease serine 3 (TMPRSS3) in radioresistance and prognosis of colorectal cancer (CRC). Methods: Standardized mean difference (SMD) and summary area under the curve (AUC) of TMPRSS3 were calculated by combining all available high-throughput data globally. The prognostic significance of TMPRSS3 was determined by Kaplan-Meier and Cox regression analyses. Results: TMPRSS3 was remarkably upregulated in 198 CRC radioresistant cases compared with nonradioresistance (SMD = 0.38, AUC = 0.71). Overexpression of TMPRSS3 was observed in 1601 CRC patients compared with control subjects without CRC. TMPRSS3 was a risk factor for disease-free survival of CRC with the summarized hazard ratio 1.28. Conclusion: TMPRSS3 contributes to the radioresistance and unfavorable prognosis of CRC.

Induction of IDO1 and Kynurenine by Serine Proteases Subtilisin, Prostate Specific Antigen, CD26 and HtrA: A New Form of Immunosuppression?

Several serine proteases have been linked to autoimmune disorders and tumour initiation although the mechanisms are not fully understood. Activation of the kynurenine pathway enzyme indoleamine-2,3-dioxygenase (IDO1) modulates cellular activity in the brain, tolerogenesis in the immune system and is a major checkpoint in cancer development. We now report that IDO1 mRNA and IDO1 protein expression (generating kynurenine) are induced in human monocyte-derived macrophages by several chymotryptic serine proteases with direct links to tumorigenesis, including Prostate Specific Antigen (PSA), CD26 (Dipeptidyl-peptidase-4, CD26/DPP-4), High Temperature Requirement protein-A (HtrA), and the bacterial virulence factor subtilisin. These proteases also induce expression of the pro-inflammatory cytokine genes IL1B and IL6. Other serine proteases tested: bacterial glu-C endopeptidase and mammalian Pro-protein Convertase Subtilase-Kexin-3 (PCSK3, furin), urokinase plasminogen activator (uPA), cathepsin G or neutrophil elastase, did not induce IDO1, indicating that the reported effects are not a general property of all serine proteases. The results represent a novel mechanism of activating immunosuppressive IDO1 and inducing kynurenine generation which, together with the production of inflammatory cytokines, would contribute to tumour initiation and progression, providing a new target for drug development. In addition, the proteasomal S20 serine protease inhibitor carfilzomib, used in the treatment of myeloma, prevented the induction of IDO1 and cytokine gene expression, potentially contributing to its clinical anti-cancer activity.

Utility of TMPRSS4 as a Prognostic Biomarker and Potential Therapeutic Target in Patients with Gastric Cancer

BACKGROUND

Transmembrane serine protease 4 (TMPRSS4) belongs to the family of type II transmembrane serine proteases that are known to be upregulated in many malignant tumors. However, there is a paucity of studies documenting the clinical impact and biological effects of TMPRSS4 on gastric cancer (GC) patients who underwent surgery.

METHODS

Tissues samples were obtained from 105 patients with GC who underwent gastrectomy followed by adjuvant chemotherapy, excluding those at stage I. The expression of TMPRSS4 was examined through immunohistochemical analysis. The association between TMPRSS4 expression and clinico-pathological features as well as prognosis was assessed. Moreover, the effects of TMPRSS4 expression on cell migration and sensitivity to 5-FU were investigated.

RESULTS

The expression rate of TMPRSS4 was 56.3% (59/105) in GC cases. The expression of TMPRSS4 was positively correlated with the depth of tumor (T) and venous (V) invasion. The 5-year overall survival (OS) and recurrence-free survival (RFS) rates of the TMPRSS4-positive group was significantly lower than that of the TMPRSS4-negative group (p=0.0001 and p=0.005, respectively). Especially, there was significant differences in OS and RFS of patients with stage III cancer between the two groups (p=0.0064 and 0.012, respectively). Multivariate analysis demonstrated that TMPRSS4 expression and the stage of cancer were crucial prognostic factors for RFS. TMPRSS4-silenced GC cells exhibited increased sensitivity to 5-FU when compared with the non-specific control siRNA-transfected cells.

CONCLUSION

TMPRSS4 can be considered as a potential prognostic biomarker, especially for stage III, and a promising therapeutic target for GC.

Identification of a novel tumour microenvironment-based prognostic biomarker in skin cutaneous melanoma

Skin cutaneous melanoma (SKCM) is one of the most destructive skin malignancies and has attracted worldwide attention. However, there is a lack of prognostic biomarkers, especially tumour microenvironment (TME)-based prognostic biomarkers. Therefore, there is an urgent need to investigate the TME in SKCM, as well as to identify efficient biomarkers for the diagnosis and treatment of SKCM patients. A comprehensive analysis was performed using SKCM samples from The Cancer Genome Atlas and normal samples from Genotype-Tissue Expression. TME scores were calculated using the ESTIMATE algorithm, and differential TME scores and differentially expressed prognostic genes were successively identified. We further identified more reliable prognostic genes via least absolute shrinkage and selection operator regression analysis and constructed a prognostic prediction model to predict overall survival. Receiver operating characteristic analysis was used to evaluate the diagnostic efficacy, and Cox regression analysis was applied to explore the relationship with clinicopathological characteristics. Finally, we identified a novel prognostic biomarker and conducted a functional enrichment analysis. After considering ESTIMATEScore and tumour purity as differential TME scores, we identified 34 differentially expressed prognostic genes. Using least absolute shrinkage and selection operator regression, we identified seven potential prognostic biomarkers (SLC13A5, RBM24, IGHV3OR16-15, PRSS35, SLC7A10, IGHV1-69D and IGHV2-26). Combined with receiver operating characteristic and regression analyses, we determined PRSS35 as a novel TME-based prognostic biomarker in SKCM, and functional analysis enriched immune-related cells, functions and signalling pathways. Our study indicated that PRSS35 could act as a potential prognostic biomarker in SKCM by investigating the TME, so as to provide new ideas and insights for the clinical diagnosis and treatment of SKCM.

TMPRSS4 promotes cancer stem-like properties in prostate cancer cells through upregulation of SOX2 by SLUG and TWIST1

Background

Transmembrane serine protease 4 (TMPRSS4) is a cell surface–anchored serine protease. Elevated expression of TMPRSS4 correlates with poor prognosis in colorectal cancer, gastric cancer, prostate cancer, non–small cell lung cancer, and other cancers. Previously, we demonstrated that TMPRSS4 promotes invasion and proliferation of prostate cancer cells. Here, we investigated whether TMPRSS4 confers cancer stem–like properties to prostate cancer cells and characterized the underlying mechanisms.

Methods

Acquisition of cancer stem–like properties by TMPRSS4 was examined by monitoring anchorage-independent growth, tumorsphere formation, aldehyde dehydrogenase (ALDH) activation, and resistance to anoikis and drugs in vitro and in an early metastasis model in vivo. The underlying molecular mechanisms were evaluated, focusing on stemness-related factors regulated by epithelial–mesenchymal transition (EMT)-inducing transcription factors. Clinical expression and significance of TMPRSS4 and stemness-associated factors were explored by analyzing datasets from The Cancer Genome Atlas (TCGA).

Results

TMPRSS4 promoted anchorage-independent growth, ALDH activation, tumorsphere formation, and therapeutic resistance of prostate cancer cells. In addition, TMPRSS4 promoted resistance to anoikis, thereby increasing survival of circulating tumor cells and promoting early metastasis. These features were accompanied by upregulation of stemness-related factors such as SOX2, BMI1, and CD133. SLUG and TWIST1, master EMT-inducing transcription factors, made essential contributions to TMPRSS4-mediated cancer stem cell (CSC) features through upregulation of SOX2. SLUG stabilized SOX2 via preventing proteasomal degradation through its interaction with SOX2, while TWIST1 upregulated transcription of SOX2 by interacting with the proximal E-box element in the SOX2 promoter. Clinical data showed that TMPRSS4 expression correlated with the levels of SOX2, PROM1, SNAI2, and TWIST1. Expression of SOX2 was positively correlated with that of TWIST1, but not with other EMT-inducing transcription factors, in various cancer cell lines.

Conclusions

Together, these findings suggest that TMPRSS4 promotes CSC features in prostate cancer through upregulation of the SLUG- and TWIST1-induced stem cell factor SOX2 beyond EMT. Thus, TMPRSS4/SLUG–TWIST1/SOX2 axis may represent a novel mechanism involved in the control of tumor progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02147-7.

Long-Acting Tumor-Activated Prodrug of a TGFβR Inhibitor

Inhibition of TGFβ signaling in concert with a checkpoint blockade has been shown to provide improved and durable antitumor immune response in mouse models. However, on-target adverse cardiovascular effects have limited the clinical use of TGFβ receptor (TGFβR) inhibitors in cancer therapy. To restrict the activity of TGFβR inhibitors to tumor tissues and thereby widen the therapeutic index, a series of tumor-activated prodrugs of a selective small molecule TGFβR1 inhibitor 1 were prepared by appending 1 to a serine protease substrate and a half-life extension fatty acid carbon chain. The prodrugs were shown to be selectively metabolized in tumor tissues relative to the heart and blood and demonstrated a prolonged favorable increase in the tumor-to-heart ratio of the active drug in tissue distribution studies. Once-weekly administration of the most tissue-selective compound 10 provided anti-tumor efficacy comparable to the parent compound and reduced systemic exposure of the active drug.

A novel class of TMPRSS2 inhibitors potently block SARS-CoV-2 and MERS-CoV viral entry and protect human epithelial lung cells

The host cell serine protease TMPRSS2 is an attractive therapeutic target for COVID-19 drug discovery. This protease activates the Spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and of other coronaviruses and is essential for viral spread in the lung. Utilizing rational structure-based drug design (SBDD) coupled to substrate specificity screening of TMPRSS2, we have discovered covalent small-molecule ketobenzothiazole (kbt) TMPRSS2 inhibitors which are structurally distinct from and have significantly improved activity over the existing known inhibitors Camostat and Nafamostat. Lead compound MM3122 (4) has an IC50 (half-maximal inhibitory concentration) of 340 pM against recombinant full-length TMPRSS2 protein, an EC50 (half-maximal effective concentration) of 430 pM in blocking host cell entry into Calu-3 human lung epithelial cells of a newly developed VSV-SARS-CoV-2 chimeric virus, and an EC50 of 74 nM in inhibiting cytopathic effects induced by SARS-CoV-2 virus in Calu-3 cells. Further, MM3122 blocks Middle East respiratory syndrome coronavirus (MERS-CoV) cell entry with an EC50 of 870 pM. MM3122 has excellent metabolic stability, safety, and pharmacokinetics in mice, with a half-life of 8.6 h in plasma and 7.5 h in lung tissue, making it suitable for in vivo efficacy evaluation and a promising drug candidate for COVID-19 treatment.

Posttranslational modifications of serine protease TMPRSS13 regulate zymogen activation, proteolytic activity, and cell surface localization

TMPRSS13, a member of the type II transmembrane serine protease (TTSP) family, harbors four N-linked glycosylation sites in its extracellular domain. Two of the glycosylated residues are located in the scavenger receptor cysteine-rich (SRCR) protein domain, while the remaining two sites are in the catalytic serine protease (SP) domain. In this study, we examined the role of N-linked glycosylation in the proteolytic activity, autoactivation, and cellular localization of TMPRSS13. Individual and combinatory site-directed mutagenesis of the glycosylated asparagine residues indicated that glycosylation of the SP domain is critical for TMPRSS13 autoactivation and catalytic activity toward one of its protein substrates, the prostasin zymogen. Additionally, SP domain glycosylation-deficient TMPRSS13 displayed impaired trafficking of TMPRSS13 to the cell surface, which correlated with increased retention in the endoplasmic reticulum. Importantly, we showed that N-linked glycosylation was a critical determinant for subsequent phosphorylation of endogenous TMPRSS13. Taken together, we conclude that glycosylation plays an important role in regulating TMPRSS13 activation and activity, phosphorylation, and cell surface localization.

Targeting Multiple Signal Transduction Pathways of SARS-CoV-2: Approaches to COVID-19 Therapeutic Candidates

Due to the complicated pathogenic pathways of coronavirus disease 2019 (COVID-19), related medicinal therapies have remained a clinical challenge. COVID-19 highlights the urgent need to develop mechanistic pathogenic pathways and effective agents for preventing/treating future epidemics. As a result, the destructive pathways of COVID-19 are in the line with clinical symptoms induced by severe acute coronary syndrome (SARS), including lung failure and pneumonia. Accordingly, revealing the exact signaling pathways, including inflammation, oxidative stress, apoptosis, and autophagy, as well as relative representative mediators such as tumor necrosis factor-α (TNF-α), nuclear factor erythroid 2-related factor 2 (Nrf2), Bax/caspases, and Beclin/LC3, respectively, will pave the road for combating COVID-19. Prevailing host factors and multiple steps of SARS-CoV-2 attachment/entry, replication, and assembly/release would be hopeful strategies against COVID-19. This is a comprehensive review of the destructive signaling pathways and host-pathogen interaction of SARS-CoV-2, as well as related therapeutic targets and treatment strategies, including potential natural products-based candidates.

A novel class of TMPRSS2 inhibitors potently block SARS-CoV-2 and MERS-CoV viral entry and protect human epithelial lung cells

The host cell serine protease TMPRSS2 is an attractive therapeutic target for COVID-19 drug discovery. This protease activates the Spike protein of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and of other coronaviruses and is essential for viral spread in the lung. Utilizing rational structure-based drug design (SBDD) coupled to substrate specificity screening of TMPRSS2, we have discovered a novel class of small molecule ketobenzothiazole TMPRSS2 inhibitors with significantly improved activity over existing irreversible inhibitors Camostat and Nafamostat. Lead compound MM3122 ( 4 ) has an IC ₅₀ of 340 pM against recombinant full-length TMPRSS2 protein, an EC ₅₀ of 430 pM in blocking host cell entry into Calu-3 human lung epithelial cells of a newly developed VSV SARS-CoV-2 chimeric virus, and an EC ₅₀ of 74 nM in inhibiting cytopathic effects induced by SARS-CoV-2 virus in Calu-3 cells. Further, MM3122 blocks Middle East Respiratory Syndrome Coronavirus (MERS-CoV) cell entry with an EC ₅₀ of 870 pM. MM3122 has excellent metabolic stability, safety, and pharmacokinetics in mice with a half-life of 8.6 hours in plasma and 7.5 h in lung tissue, making it suitable for in vivo efficacy evaluation and a promising drug candidate for COVID-19 treatment.

Gene Families With Stochastic Exclusive Gene Choice Underlie Cell Adhesion in Mammalian Cells

Exclusive stochastic gene choice combines precision with diversity. This regulation enables most T-cells to express exactly one T-cell receptor isoform chosen from a large repertoire, and to react precisely against diverse antigens. Some cells express two receptor isoforms, revealing the stochastic nature of this process. A similar regulation of odorant receptors and protocadherins enable cells to recognize odors and confer individuality to cells in neuronal interaction networks, respectively. We explored whether genes in other families are expressed exclusively by analyzing single-cell RNA-seq data with a simple metric. This metric can detect exclusivity independently of the mean value and the monoallelic nature of gene expression. Chromosomal segments and gene families are more likely to express genes concurrently than exclusively, possibly due to the evolutionary and biophysical aspects of shared regulation. Nonetheless, gene families with exclusive gene choice were detected in multiple cell types, most of them are membrane proteins involved in ion transport and cell adhesion, suggesting the coordination of these two functions. Thus, stochastic exclusive expression extends beyond the prototypical families, permitting precision in gene choice to be combined with the diversity of intercellular interactions.

Interstitial Deletions Generating Fusion Genes

A fusion gene is the physical juxtaposition of two different genes resulting in a structure consisting of the head of one gene and the tail of the other. Gene fusion is often a primary neoplasia-inducing event in leukemias, lymphomas, solid malignancies as well as benign tumors. Knowledge about fusion genes is crucial not only for our understanding of tumorigenesis, but also for the diagnosis, prognostication, and treatment of cancer. Balanced chromosomal rearrangements, in particular translocations and inversions, are the most frequent genetic events leading to the generation of fusion genes. In the present review, we summarize the existing knowledge on chromosome deletions as a mechanism for fusion gene formation. Such deletions are mostly submicroscopic and, hence, not detected by cytogenetic analyses but by array comparative genome hybridization (aCGH) and/or high throughput sequencing (HTS). They are found across the genome in a variety of neoplasias. As tumors are increasingly analyzed using aCGH and HTS, it is likely that more interstitial deletions giving rise to fusion genes will be found, significantly impacting our understanding and treatment of cancer.

The Kunitz-type serine protease inhibitor Spint2 is required for cellular cohesion, coordinated cell migration and cell survival during zebrafish hatching gland development

We have previously shown that the Kunitz-type serine protease inhibitor Spint1a, also named Hai1a, is required in the zebrafish embryonic epidermis to restrict the activity of the type II transmembrane serine protease (TTSP) Matriptase1a/St14a, thereby ensuring epidermal homeostasis. A closely related Kunitz-type inhibitor is Spint2/Hai2, which in mammals plays multiple developmental roles that are either redundant or non-redundant with those of Spint1. However, the molecular bases for these non-redundancies are not fully understood. Here, we study spint2 during zebrafish development. It is co-expressed with spint1a in multiple embryonic epithelia, including the outer/peridermal layer of the epidermis. However, unlike spint1a, spint2 expression is absent from the basal epidermal layer but present in hatching gland cells. Hatching gland cells derive from the mesendodermal prechordal plate, from where they undergo a thus far undescribed transit into, and coordinated sheet migration within, the interspace between the outer and basal layer of the epidermis to reach their final destination on the yolk sac. Hatching gland cells usually survive their degranulation that drives embryo hatching but die several days later. In spint2 mutants, cohesion among hatching gland cells and their collective intra-epidermal migration are disturbed, leading to a discontinuous organization of the gland. In addition, cells undergo precocious cell death before degranulation, so that embryos fail to hatch. Chimera analyses show that Spint2 is required in hatching gland cells, but not in the overlying periderm, their potential migration and adhesion substrate. Spint2 acts independently of all tested Matriptases, Prostasins and other described Spint1 and Spint2 mediators. However, it displays a tight genetic interaction with and acts at least partly via the cell-cell adhesion protein E-cadherin, promoting both hatching gland cell cohesiveness and survival, in line with formerly reported effects of E-cadherin during morphogenesis and cell death suppression. In contrast, no such genetic interaction was observed between Spint2 and the cell-cell adhesion molecule EpCAM, which instead interacts with Spint1a. Our data shed new light onto the mechanisms of hatching gland morphogenesis and hatching gland cell survival. In addition, they reveal developmental roles of Spint2 that are strikingly different from those of Spint1, most likely due to differences in the expression patterns and relevant target proteins.

Hepsin: a multifunctional transmembrane serine protease in pathobiology

Cell membrane-bound serine proteases are important in the maintenance of physiological homeostasis. Hepsin is a type II transmembrane serine protease highly expressed in the liver. Recent studies indicate that hepsin activates prohepatocyte growth factor in the liver to enhance Met signaling, thereby regulating glucose, lipid, and protein metabolism. In addition, hepsin functions in nonhepatic tissues, including the adipose tissue, kidney, and inner ear, to regulate adipocyte differentiation, urinary protein processing, and auditory function, respectively. In mouse models, hepsin deficiency lowers blood glucose, lipid, and protein levels, impairs uromodulin assembly in renal epithelial cells, and causes hearing loss. Elevated hepsin expression has also been found in many cancers. As a type II transmembrane protease, cell surface expression and zymogen activation are essential for hepsin activity. In this review, we discuss the current knowledge regarding hepsin biosynthesis, activation, and functions in pathobiology.

Priming of SARS-CoV-2 S protein by several membrane-bound serine proteinases could explain enhanced viral infectivity and systemic COVID-19 infection

The ongoing COVID-19 pandemic has already caused over a million deaths worldwide, and this death toll will be much higher before effective treatments and vaccines are available. The causative agent of the disease, the coronavirus SARS-CoV-2, shows important similarities with the previously emerged SARS-CoV-1, but also striking differences. First, SARS-CoV-2 possesses a significantly higher transmission rate and infectivity than SARS-CoV-1 and has infected in a few months over 60 million people. Moreover, COVID-19 has a systemic character, as in addition to the lungs, it also affects the heart, liver, and kidneys among other organs of the patients and causes frequent thrombotic and neurological complications. In fact, the term "viral sepsis" has been recently coined to describe the clinical observations. Here I review current structure-function information on the viral spike proteins and the membrane fusion process to provide plausible explanations for these observations. I hypothesize that several membrane-associated serine proteinases (MASPs), in synergy with or in place of TMPRSS2, contribute to activate the SARS-CoV-2 spike protein. Relative concentrations of the attachment receptor, ACE2, MASPs, their endogenous inhibitors (the Kunitz-type transmembrane inhibitors, HAI-1/SPINT1 and HAI-2/SPINT2, as well as major circulating serpins) would determine the infection rate of host cells. The exclusive or predominant expression of major MASPs in specific human organs suggests a direct role of these proteinases in e.g., heart infection and myocardial injury, liver dysfunction, kidney damage, as well as neurological complications. Thorough consideration of these factors could have a positive impact on the control of the current COVID-19 pandemic.

Prospects for Using Expression Patterns of Paramyxovirus Receptors as Biomarkers for Oncolytic Virotherapy

Simple Summary

Some non-pathogenic viruses that do not cause serious illness in humans can efficiently target and kill cancer cells and may be considered candidates for cancer treatment with virotherapy. However, many cancer cells are protected from viruses. An important goal of personalized cancer treatment is to identify viruses that can kill a certain type of cancer cells. To this end, researchers investigate expression patterns of cell entry receptors, which viruses use to bind to and enter host cells. We summarized and analyzed the receptor expression patterns of two paramyxoviruses: The non-pathogenic measles and the Sendai viruses. The receptors for these viruses are different and can be proteins or lipids with attached carbohydrates. This review discusses the prospects for using these paramyxovirus receptors as biomarkers for successful personalized virotherapy for certain types of cancer.

Abstract

The effectiveness of oncolytic virotherapy in cancer treatment depends on several factors, including successful virus delivery to the tumor, ability of the virus to enter the target malignant cell, virus replication, and the release of progeny virions from infected cells. The multi-stage process is influenced by the efficiency with which the virus enters host cells via specific receptors. This review describes natural and artificial receptors for two oncolytic paramyxoviruses, nonpathogenic measles, and Sendai viruses. Cell entry receptors are proteins for measles virus (MV) and sialylated glycans (sialylated glycoproteins or glycolipids/gangliosides) for Sendai virus (SeV). Accumulated published data reviewed here show different levels of expression of cell surface receptors for both viruses in different malignancies. Patients whose tumor cells have low or no expression of receptors for a specific oncolytic virus cannot be successfully treated with the virus. Recent published studies have revealed that an expression signature for immune genes is another important factor that determines the vulnerability of tumor cells to viral infection. In the future, a combination of expression signatures of immune and receptor genes could be used to find a set of oncolytic viruses that are more effective for specific malignancies.

A rational roadmap for SARS-CoV-2/COVID-19 pharmacotherapeutic research and development: IUPHAR Review 29

In this review, we identify opportunities for drug discovery in the treatment of COVID-19 and, in so doing, provide a rational roadmap whereby pharmacology and pharmacologists can mitigate against the global pandemic. We assess the scope for targeting key host and viral targets in the mid-term, by first screening these targets against drugs already licensed, an agenda for drug repurposing, which should allow rapid translation to clinical trials. A simultaneous, multi-pronged approach using conventional drug discovery methods aimed at discovering novel chemical and biological means of targeting a short list of host and viral entities which should extend the arsenal of anti-SARS-CoV-2 agents. This longer term strategy would provide a deeper pool of drug choices for future-proofing against acquired drug resistance. Second, there will be further viral threats, which will inevitably evade existing vaccines. This will require a coherent therapeutic strategy which pharmacology and pharmacologists are best placed to provide. LINKED ARTICLES: This article is part of a themed issue on The Pharmacology of COVID-19. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.21/issuetoc.

Inhibitors of type II transmembrane serine proteases in the treatment of diseases of the respiratory tract - A review of patent literature

INTRODUCTION

Type II transmembrane serine proteases (TTSPs) of the human respiratory tract generate high interest owing to their ability, among other roles, to cleave surface proteins of respiratory viruses. This step is critical in the viral invasion of coronaviruses, including SARS-CoV-2 responsible for COVID-19, but also influenza viruses and reoviruses. Accordingly, these cell surface enzymes constitute appealing therapeutic targets to develop host-based therapeutics against respiratory viral diseases. Additionally, their deregulated levels or activity has been described in non-viral diseases such as fibrosis, cancer, and osteoarthritis, making them potential targets in these indications.

AREAS COVERED

Areas covered: This review includes WIPO-listed patents reporting small molecules and peptide-based inhibitors of type II transmembrane serine proteases of the respiratory tract.

EXPERT OPINION

Expert opinion: Several TTSPs of the respiratory tract represent attractive pharmacological targets in the treatment of respiratory infectious diseases (notably COVID-19 and influenza), but also against idiopathic pulmonary fibrosis and lung cancer. The current emphasis is primarily on TMPRSS2, matriptase, and hepsin, yet other TTSPs await validation. Compounds listed herein are predominantly peptidomimetic inhibitors, some with covalent reversible mechanisms of action and high potencies. Their selectivity profile, however, are often only partially characterized. Preclinical data are promising and warrant further advancement in the above diseases.

Hepatocyte growth factor/MET and CD44 in colorectal cancer: partners in tumorigenesis and therapy resistance

Intestinal epithelial self-renewal is a tightly controlled process, which is critically dependent on WNT signalling. Aberrant activation of the WNT pathway in intestinal stem cells (ISCs) results in constitutive transcription of target genes, which collectively drive malignant transformation in colorectal cancer (CRC). However, the contribution of individual genes to intestinal homeostasis and tumorigenesis often is incompletely defined. Here, we discuss converging evidence indicating that the receptor tyrosine kinase (RTK) MET and its ligand hepatocyte growth factor (HGF) play a major role in the intestinal damage response, as well as in intestinal tumorigenesis, by controlling the proliferation, survival, motility, and stemness of normal and neoplastic intestinal epithelial cells. These activities of MET are promoted by specific CD44 isoforms expressed by ISCs. The accrued data indicate that MET and the EGFR have overlapping roles in the biology of intestinal epithelium and that metastatic CRCs can exploit this redundancy to escape from EGFR-targeted treatments, co-opting HGF/MET/CD44v signalling. Hence, targeting both pathways may be required for effective treatment of (a subset of) CRCs. The RTK identity of MET, the distinctive 'plasminogen-like' structure and activation mode of its ligand HGF, and the specific collaboration of MET with CD44, provide several unique targeting options, which merit further exploration.

Proteolytic cleavage of Podocin by Matriptase exacerbates podocyte injury

Podocyte injury is a critical step toward the progression of renal disease and is often associated with a loss of slit diaphragm proteins, including Podocin. Although there is a possibility that the extracellular domain of these slit diaphragm proteins can be a target for a pathological proteolysis, the precise mechanism driving the phenomenon remains unknown. Here we show that Matriptase, a membrane-anchored protein, was activated at podocytes in CKD patients and mice, whereas Matriptase inhibitors slowed the progression of mouse kidney disease. The mechanism could be accounted for by an imbalance favoring Matriptase over its cognate inhibitor, hepatocyte growth factor activator inhibitor type 1 (HAI-1), because conditional depletion of HAI-1 in podocytes accelerated podocyte injury in mouse model. Matriptase was capable of cleaving Podocin, but such a reaction was blocked by either HAI-1 or dominant-negative Matriptase. Furthermore, the N terminus of Podocin, as a consequence of Matriptase cleavage of Podocin, translocated to nucleoli, suggesting that the N terminus of Podocin might be involved in the process of podocyte injury. Given these observations, we propose that the proteolytic cleavage of Podocin by Matriptase could potentially cause podocyte injury and that targeting Matriptase could be a novel therapeutic strategy for CKD patients.

The cell-surface anchored serine protease TMPRSS13 promotes breast cancer progression and resistance to chemotherapy

Breast cancer progression is accompanied by increased expression of extracellular and cell-surface proteases capable of degrading the extracellular matrix as well as cleaving and activating downstream targets. The type II transmembrane serine proteases (TTSPs) are a family of cell-surface proteases that play critical roles in numerous types of cancers. Therefore, the aim of this study was to identify novel and uncharacterized TTSPs with differential expression in breast cancer and to determine their potential roles in progression. Systematic in silico data analysis followed by immunohistochemical validation identified increased expression of the TTSP family member, TMPRSS13 (transmembrane protease, serine 13), in invasive ductal carcinoma patient tissue samples compared to normal breast tissue. To test whether loss of TMPRSS13 impacts tumor progression, TMPRSS13 was genetically ablated in the oncogene-induced transgenic MMTV-PymT tumor model. TMPRSS13 deficiency resulted in a significant decrease in overall tumor burden and growth rate, as well as a delayed formation of detectable mammary tumors, thus suggesting a causal relationship between TMPRSS13 expression and the progression of breast cancer. Complementary studies using human breast cancer cell culture models revealed that siRNA-mediated silencing of TMPRSS13 expression decreases proliferation, induces apoptosis, and attenuates invasion. Importantly, targeting TMPRSS13 expression renders aggressive triple-negative breast cancer cell lines highly responsive to chemotherapy. At the molecular level, knockdown of TMPRSS13 in breast cancer cells led to increased protein levels of the tumor-suppressive protease prostasin. TMPRSS13/prostasin co-immunoprecipitation and prostasin zymogen activation experiments identified prostasin as a potential novel target for TMPRSS13. Regulation of prostasin levels may be a mechanism that contributes to the pro-oncogenic properties of TMPRSS13 in breast cancer. TMPRSS13 represents a novel candidate for targeted therapy in combination with standard of care chemotherapy agents in patients with hormone receptor-negative breast cancer or in patients with tumors refractory to endocrine therapy.

Existence of SARS-CoV-2 Entry Molecules in the Oral Cavity

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor, angiotensin-converting enzyme 2 (ACE2), transmembrane protease serine 2 (TMPRSS2), and furin, which promote entry of the virus into the host cell, have been identified as determinants of SARS-CoV-2 infection. Dorsal tongue and gingiva, saliva, and tongue coating samples were examined to determine the presence of these molecules in the oral cavity. Immunohistochemical analyses showed that ACE2 was expressed in the stratified squamous epithelium of the dorsal tongue and gingiva. TMPRSS2 was strongly expressed in stratified squamous epithelium in the keratinized surface layer and detected in the saliva and tongue coating samples via Western blot. Furin was localized mainly in the lower layer of stratified squamous epithelium and detected in the saliva but not tongue coating. ACE2, TMPRSS2, and furin mRNA expression was observed in taste bud-derived cultured cells, which was similar to the immunofluorescence observations. These data showed that essential molecules for SARS-CoV-2 infection were abundant in the oral cavity. However, the database analysis showed that saliva also contains many protease inhibitors. Therefore, although the oral cavity may be the entry route for SARS-CoV-2, other factors including protease inhibitors in the saliva that inhibit viral entry should be considered.

Large-scale discovery of male reproductive tract-specific genes through analysis of RNA-seq datasets

Background

The development of a safe, effective, reversible, non-hormonal contraceptive method for men has been an ongoing effort for the past few decades. However, despite significant progress on elucidating the function of key proteins involved in reproduction, understanding male reproductive physiology is limited by incomplete information on the genes expressed in reproductive tissues, and no contraceptive targets have so far reached clinical trials. To advance product development, further identification of novel reproductive tract-specific genes leading to potentially druggable protein targets is imperative.

Results

In this study, we expand on previous single tissue, single species studies by integrating analysis of publicly available human and mouse RNA-seq datasets whose initial published purpose was not focused on identifying male reproductive tract-specific targets. We also incorporate analysis of additional newly acquired human and mouse testis and epididymis samples to increase the number of targets identified. We detected a combined total of 1178 genes for which no previous evidence of male reproductive tract-specific expression was annotated, many of which are potentially druggable targets. Through RT-PCR, we confirmed the reproductive tract-specific expression of 51 novel orthologous human and mouse genes without a reported mouse model. Of these, we ablated four epididymis-specific genes (Spint3, Spint4, Spint5, and Ces5a) and two testis-specific genes (Pp2d1 and Saxo1) in individual or double knockout mice generated through the CRISPR/Cas9 system. Our results validate a functional requirement for Spint4/5 and Ces5a in male mouse fertility, while demonstrating that Spint3, Pp2d1, and Saxo1 are each individually dispensable for male mouse fertility.

Conclusions

Our work provides a plethora of novel testis- and epididymis-specific genes and elucidates the functional requirement of several of these genes, which is essential towards understanding the etiology of male infertility and the development of male contraceptives.

TMPRSS13 promotes cell survival, invasion, and resistance to drug-induced apoptosis in colorectal cancer

Cancer progression is often accompanied by increased levels of extracellular proteases capable of remodeling the extracellular matrix and promoting pro-cancerous signaling pathways by activating growth factors and receptors. The type II transmembrane serine protease (TTSP) family encompasses several proteases that play critical roles in cancer progression; however, the expression or function of the TTSP TMPRSS13 in carcinogenesis has not been examined. In the present study, we found TMPRSS13 to be differentially expressed at both the transcript and protein levels in human colorectal cancer (CRC). Immunohistochemical analyses revealed consistent high expression of TMPRSS13 protein on the cancer cell surface in CRC patient samples; in contrast, the majority of normal colon samples displayed no detectable expression. On a functional level, TMPRSS13 silencing in CRC cell lines increased apoptosis and impaired invasive potential. Importantly, transgenic overexpression of TMPRSS13 in CRC cell lines increased tolerance to apoptosis-inducing agents, including paclitaxel and HA14-1. Conversely, TMPRSS13 silencing rendered CRC cells more sensitive to these agents. Together, our findings suggest that TMPRSS13 plays an important role in CRC cell survival and in promoting resistance to drug-induced apoptosis; we also identify TMPRSS13 as a potential new target for monotherapy or combination therapy with established chemotherapeutics to improve treatment outcomes in CRC patients.