Cathepsin K associates with lymph node metastasis and poor prognosis in oral squamous cell carcinoma

dia-PASEF Proteomics of Tumor and Stroma LMD Enriched from Archived HNSCC Samples

We employed laser microdissection to selectively harvest tumor cells and stroma from the microenvironment of formalin-fixed, paraffin-embedded head and neck squamous cell carcinoma (HNSCC) tissues. The captured HNSCC tissue fractions were analyzed by quantitative mass spectrometry-based proteomics using a data independent analysis approach. In paired samples, we achieved excellent proteome coverage having quantified 6,668 proteins with a median quantitative coefficient of variation under 10%. We observed significant differences in relevant functional pathways between the spatially resolved tumor and stroma regions. Our results identified extracellular matrix (ECM) as a major component enriched in the stroma, including many cancer associated fibroblast signature proteins in this compartment. We demonstrate the potential for comparative deep proteome analysis from very low starting input in a scalable format that is useful to decipher the alterations in tumor and the stromal microenvironment. Correlating such results with clinical features or disease progression will likely enable identification of novel targets for disease classification and interventions.

Reduced expression of cathepsin F predicts poor prognosis in patients with clear cell renal cell carcinoma

Abnormalities in the extracellular matrix (ECM) play important roles in the regulation and progression of clear cell renal cell carcinoma (ccRCC). The cysteine cathepsin is one of the major proteases involved in ECM remodeling and has been shown to be aberrantly expressed in multiple cancer types. However, the clinical significance and biological function of distinct cysteine cathepsins in ccRCC remain poorly understood. In this study, several bioinformatics databases, including UALCAN, TIMER, GEPIA and the Human Protein Atlas datasets, were used to analyze the expression and prognostic value of different cysteine cathepsin family members in ccRCC. We found that the expression level of CTSF was downregulated in tumor tissues and closely related to the poor survival of ccRCC patients. Further in vitro experiments suggested that CTSF overexpression suppressed the proliferation and migration of ccRCC cells. Moreover, the expression of CTSF was shown to be associated with several immune-infiltrating cells and immunomodulators in ccRCC. These results indicated that CTSF might be a promising diagnostic and prognostic marker in ccRCC.

The potential contribution of aberrant cathepsin K expression to gastric cancer pathogenesis

The role of cathepsin K (CTSK) expression in the pathogenesis and progression of gastric cancer (GC) remains unclear. Hence, the primary objective of this study is to elucidate the precise expression and biological role of CTSK in GC by employing a combination of bioinformatics analysis and in vitro experiments. Our findings indicated a significant upregulation of CTSK in GC. The bioinformatics analysis revealed that GC patients with a high level of CTSK expression exhibited enrichment of hallmark gene sets associated with angiogenesis, epithelial-mesenchymal transition (EMT), inflammatory response, KRAS signaling up, TNFα signaling via KFκB, IL2-STAT5 signaling, and IL6-JAK-STAT3 signaling. Additionally, these patients demonstrated elevated levels of M2-macrophage infiltration, which was also correlated with a poorer prognosis. The results of in vitro experiments provided confirmation that the over-expression of CTSK leads to an increase in the proliferative and invasive abilities of GC cells. However, further evaluation was necessary to determine the impact of CTSK on the migration capability of these cells. Our findings suggested that CTSK has the potential to facilitate the initiation and progression of GC by augmenting the invasive capacity of GC cells, engaging in tumor-associated EMT, and fostering the establishment of an immunosuppressive tumor microenvironment (TME).

Cathepsin-K inhibition enhances anti-cancerous activity within oral squamous cell carcinoma cells: Uncloaking the potency of new K21 formulation

BACKGROUND

The ability of cancer cells to be invasive and metastasize depend on several factors, of which the action of protease activity takes center stage in disease progression.

PURPOSE/OBJECTIVE

To analyze function of new K21 molecule in the invasive process of oral squamous cell carcinoma (OSCC) cell line.

MATERIALS & METHODS

The Fusobacterium (ATCC 23726) streaks were made, and pellets were resuspended in Cal27 (ATCC CRL-2095) OSCC cell line spheroid cell microplate. Cells were seeded and Lysotracker staining performed for CathepsinK red channel. Cell and morphology were evaluated using Transmission Electron microscopy. Thiobarbituric acid assay was performed. OSCC was analyzed for Mic60. Raman spectra were collected from the cancer cell line. L929 dermal fibroblast cells were used for Scratch Assay. ELISA muti arrays were used for cytokines and matrix molecules. Internalization ability of fibroblast cells were also analyzed. Structure of K21 as a surfactant molecule with best docked poses were presented.

RESULTS

Decrease in lysosomal staining was observed after 15 and 30 min of 0.1% treatment. Tumor clusters were associated with cell membrane destruction in K21 primed cells. There was functional silencing of Mic60 via K21, especially with 1% concentration with reduced cell migration and invasiveness. Raman intensity differences were seen at 700 cm^-1, 1200 cm^-1 and 1600 cm^-1 regions. EVs were detected within presence of fibroblast cells amongst K21 groups. Wound area and wound closure showed the progress of wound healing.

CONCLUSION

Over expression of CatK can be reduced by a newly developed targeted K21 based drug delivery system leading to reduced migration and adhesion of oral squamous cell carcinoma cells. The K21 drug formulation can have great potential for cancer therapies due to targeting and cytotoxicity effects.

Cathepsin K inhibition induces Raptor destabilization and mitochondrial dysfunction via Syk/SHP2/Src/OTUB1 axis-mediated signaling

The Raptor signaling pathway is a critical point of intervention in the invasion and progression of cancer. The non-receptor tyrosine kinase Src-mediated phosphorylation of OTUB1-Y26 plays a critical role in Raptor stabilization, whereas cathepsin K inhibitor (odanacatib; ODN) and knockdown (siRNA) induce Raptor destabilization. However, the mechanisms involved in cathepsin K inhibition-induced OTUB1-Y26 phosphorylation in Raptor stabilization have not been yet elucidated. This study showed that cathepsin K inhibition activates SHP2, a tyrosine phosphatase, that dephosphorylates OTUB1 and destabilizes Raptor, whereas SHP2 deletion and pharmacological inhibition increase OTUB1-Y26 phosphorylation and Raptor expression. SHP2 deletion also led to the inhibition of ODN-induced mitochondrial ROS, fusion, and dysfunction. Furthermore, cathepsin K inhibition phosphorylated spleen tyrosine kinase (Syk) at Y525 and Y526, resulting in the SHP2-mediated dephosphorylation of OTUB1-Y26. Collectively, our findings identified Syk not only as an upstream tyrosine kinase required for SHP2 activation but also showed a critical mechanism that regulates ODN-induced Raptor downregulation and mitochondrial dysfunction. In conclusion, Syk/SHP2/Src/OTUB1 axis-mediated signaling can act as a therapeutic target in cancer management.

Cathepsin protease expression in infiltrative soft tissue sarcomas: cathepsin-K correlates with infiltrative tumor growth and clinical outcomes

Cathepsin proteases, activated in the lysosomes, are upregulated in many cancers. Intraoperative detection systems of microscopic residual tumor using cathepsin-mediated release of fluorescent nanoparticles may guide surgical excisions to improve local control. We sought to define the genetic and proteomic expression of cathepsins and their clinicopathological correlates in myxofibrosarcoma and undifferentiated pleomorphic sarcoma (UPS)-soft tissue sarcomas with high rates of positive resection margins and local recurrence-and to establish a cellular justification for cathepsin-dependent systems to identify residual cancer in the resection bed. Real-time quantitative polymerase chain reaction analysis of 58 fresh-frozen tumor specimens revealed that 56 (97%) had elevated mRNA expression of ≥1 cathepsin, including cathepsin-B (79%), cathepsin-K (59%), cathepsin-L (71%), and -S (71%). Immunohistochemical analysis of these fresh-frozen specimens revealed that 98% of tumors were positive for one or more of cathepsin-B (85%), cathepsin-K (50%), cathepsin-L (63%), and -S (10%). Strong cathepsin-K expression was associated with greater risks of local recurrence (hazard ratio, 3.78; p = 0.044) and disease-specific mortality (hazard ratio, 3.70; p = 0.025). Immunohistochemical analysis of 33 formalin-fixed paraffin-embedded block samples revealed that 97% were positive for cathepsin-B (88%), cathepsin-K (76%), cathepsin-L (52%), or -S (52%) at the tumor periphery; cathepsin-K positivity correlated with a radiographic tail-like sign (p = 0.004) and microscopic infiltrative growth (p = 0.020). We conclude that cathepsins are broadly overexpressed in myxofibrosarcoma and UPS, and cathepsin-K may be an immunohistochemical marker of local infiltration and poorer prognosis that could be used to guide precision surgery.

BAP1 phosphorylation-mediated Sp1 stabilization plays a critical role in cathepsin K inhibition-induced C-terminal p53-dependent Bax upregulation

Cathepsin K inhibitor (odanacatib; ODN) and cathepsin K knockdown (siRNA) enhance oxaliplatin-induced apoptosis through p53-dependent Bax upregulation. However, its underlying mechanisms remain unclear. In this study, we elucidated the mechanism behind enhancement of oxaliplatin-induced apoptosis by ODN. We also investigated the molecular mechanisms of ODN-induced Bax upregulation. Here, we demonstrated that ODN-induced Bax upregulation required p53, but it was independent of p53 transcriptional activity. Various mutants of the DNA-binding domain of p53 induced Bax upregulation in ODN-treated cells. p53 functional domain analysis showed that the C-terminal domain of p53 participates in the physical interaction and stabilization of Sp1, a major transcription factor of Bax. We screened a specific siRNA encoding 50 deubiquitinases and identified that BAP1 stabilizes Sp1. The knockdown or catalytic mutant form of BAP1 abolished the ODN-induced upregulation of Sp1 and Bax expression. Mechanistically, ODN induced BAP1 phosphorylation and enhanced Sp1-BAP1 interaction, resulting in Sp1 ubiquitination and degradation. Interestingly, ODN-induced BAP1 phosphorylation and DNA damage were modulated by the production of mitochondrial reactive oxygen species (ROS). Mitochondrial ROS scavengers prevented DNA damage, BAP1-mediated Sp1 stabilization, and Bax upregulation by ODN. BAP1 downregulation by siRNA inhibited apoptosis induced by the combined treatment of ODN and oxaliplatin/etoposide. Therefore, Sp1 is a crucial transcription factor for ODN-induced Bax upregulation, and Sp1 stabilization is regulated by BAP1.

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Odanacatib (ODN) enhances oxaliplatin-induced apoptosis by upregulating Bax.

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ODN-mediated Bax upregulation is independent of p53 transcriptional activity.

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C-terminal domain of p53 induces Sp1 stabilization linked to BAP1 phosphorylation.

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ODN-mediated mitochondrial ROS generation causes BAP1 phosphorylation and DNA damage.

Highly potent inhibitors of cathepsin K with a differently positioned cyanohydrazide warhead: structural analysis of binding mode to mature and zymogen-like enzymes

Cathepsin K (CatK) is a target for the treatment of osteoporosis, arthritis, and bone metastasis. Peptidomimetics with a cyanohydrazide warhead represent a new class of highly potent CatK inhibitors; however, their binding mechanism is unknown. We investigated two model cyanohydrazide inhibitors with differently positioned warheads: an azadipeptide nitrile Gü1303 and a 3-cyano-3-aza-β-amino acid Gü2602. Crystal structures of their covalent complexes were determined with mature CatK as well as a zymogen-like activation intermediate of CatK. Binding mode analysis, together with quantum chemical calculations, revealed that the extraordinary picomolar potency of Gü2602 is entropically favoured by its conformational flexibility at the nonprimed-primed subsites boundary. Furthermore, we demonstrated by live cell imaging that cyanohydrazides effectively target mature CatK in osteosarcoma cells. Cyanohydrazides also suppressed the maturation of CatK by inhibiting the autoactivation of the CatK zymogen. Our results provide structural insights for the rational design of cyanohydrazide inhibitors of CatK as potential drugs.

The Crossroads of Periodontitis and Oral Squamous Cell Carcinoma: Immune Implications and Tumor Promoting Capacities

Periodontitis (PD) is increasingly considered to interact with and promote a number of inflammatory diseases, including cancer. In the case of oral squamous cell carcinoma (OSCC) the local inflammatory response associated with PD is capable of triggering altered cellular events that can promote cancer cell invasion and proliferation of existing primary oral carcinomas as well as supporting the seeding of metastatic tumor cells into the gingival tissue giving rise to secondary tumors. Both the immune and stromal components of the periodontium exhibit phenotypic alterations and functional differences during PD that result in a microenvironment that favors cancer progression. The inflammatory milieu in PD is ideal for cancer cell seeding, migration, proliferation and immune escape. Understanding the interactions governing this attenuated anti-tumor immune response is vital to unveil unexplored preventive or therapeutic possibilities. Here we review the many commonalities between the oral-inflammatory microenvironment in PD and oral-inflammatory responses that are associated with OSCC progression, and how these conditions can act to promote and sustain the hallmarks of cancer.

Inhibition of cathepsin K sensitizes oxaliplatin-induced apoptotic cell death by Bax upregulation through OTUB1-mediated p53 stabilization in vitro and in vivo

Cathepsin K is highly expressed in various types of cancers. However, the effect of cathepsin K inhibition in cancer cells is not well characterized. Here, cathepsin K inhibitor (odanacatib; ODN) and knockdown of cathepsin K (siRNA) enhanced oxaliplatin-induced apoptosis in multiple cancer cells through Bax upregulation. Bax knockdown significantly inhibited the combined ODN and oxaliplatin treatment-induced apoptotic cell death. Stabilization of p53 by ODN played a critical role in upregulating Bax expression at the transcriptional level. Casein kinase 2 (CK2)-dependent phosphorylation of OTUB1 at Ser16 played a critical role in ODN- and cathepsin K siRNA-mediated p53 stabilization. Interestingly, ODN-induced p53 and Bax upregulation were modulated by the production of mitochondrial reactive oxygen species (ROS). Mitochondrial ROS scavengers prevented OTUB1-mediated p53 stabilization and Bax upregulation by ODN. These in vitro results were confirmed by in mouse xenograft model, combined treatment with ODN and oxaliplatin significantly reduced tumor size and induced Bax upregulation. Furthermore, human renal clear carcinoma (RCC) tissues revealed a strong correlation between phosphorylation of OTUB1(Ser16) and p53/Bax expression. Our results demonstrate that cathepsin K inhibition enhances oxaliplatin-induced apoptosis by increasing OTUB1 phosphorylation via CK2 activation, thereby promoting p53 stabilization, and hence upregulating Bax.

Ovarian Mucinous Carcinoma in a Pediatric Patient With Maroteaux-Lamy Syndrome

Mucopolysaccharidoses (MPS) are autosomal recessive lysosomal storage disorder (LSD). Mucinous ovarian cancer is a rare tumor and seldom encounters among adolescents. Here we describe an adolescent female with MPS type VI diagnosed with mucinous ovarian cancer. To our knowledge, this is the first case report of ovarian mucinous carcinoma in a patient with MPS. The association between MPS and cancer has never been described so far, but some LSD are known to have an increased risk of malignancies. The pathogenetic link between LSD and cancer is not well understood. Several potential mechanisms have been proposed for pathogenesis, which include chronic inflammation, abnormal function of activated macrophages, and genetic modifiers. Further studies are required, to understand the role of LSD in cancer.

EPHB4 Regulates the Proliferation and Metastasis of Oral Squamous Cell Carcinoma through the HMGB1/NF-κB Signalling Pathway

Background: Malignant proliferation and cervical lymphatic metastasis restrict the prognosis of oral squamous cell carcinoma (OSCC). Erythropoietin-producing human hepatocellular B4 (EPHB4) regulates a series of tumour functions involving tumourigenesis, cancer cell attachment and metastasis. However, the mechanism of EphB4 regulating the malignant progression of OSCC has not been fully elucidated. Methods: EPHB4 expression was analysed in 65 OSCC samples and adjacent noncancerous tissues through immunohistochemistry (IHC). siRNA and overexpression plasmids were transfected into OSCC cells to modify EPHB4 expression, and then, regulatory functions were explored in vitro and in vivo. Co-immunoprecipitation (Co-IP) and mass spectrometry were applied to detect proteins interacting with EPHB4. Subsequently, protein stability assays and NF-κB pathway inhibition assays were used to verify the regulation of EPHB4, high-mobility group box 1 (HMGB1) and nuclear factor-κB (NF-κB) activation. Results: EPHB4 was found to be highly expressed in OSCC tissues, which was related to tumour stage and lymphatic metastasis and resulted in a poor prognosis. Cellular experiments and mouse tongue xenograft models further confirmed that high EPHB4 expression promoted the proliferation and metastasis of OSCC tumours. Mechanistically, co-IP and mass spectrometry studies indicated that EPHB4 could bind to HMGB1 and maintain HMGB1 stability. Downregulation of HMGB1 inhibited the proliferation and metastasis of OSCC cells and inhibited NF-κB phosphorylation activation but did not affect EPHB4 expression. Conclusion: This study revealed the mechanism by which EPHB4 promotes the proliferation and metastasis of OSCC by activating the HMGB1-mediated NF-κB signalling pathway, which can be exploited as a novel marker or therapeutic target to control metastasis and improve the survival rate of OSCC.

Dlx5 promotes cancer progression through regulation of CCND1 in oral squamous cell carcinoma (OSCC)

Genetic studies have revealed a critical role of the distal-less homeobox gene 5 (Dlx5) in the pathogenesis of ovarian cancer, lung cancer, and T-cell lymphoma; however, the role and underlying mechanisms of Dlx5 in oral squamous cell carcinoma (OSCC) are largely unknown. In this study, we demonstrated that Dlx5 is up-regulated in OSCC tissues and cell lines, compared with their control groups. The results from our immunohistochemistry (IHC) analyses show that high expression levels of Dlx5 correlated with advanced TNM stages (P = 0.0001), lymph node metastasis (P = 0.0049), poor cellular differentiation (P = 0.0491), location of the tumors (P = 0.0132), and poor prognosis for the patient. We also demonstrated that knockdown of Dlx5 inhibited the viability, proliferation, and colony formation of OSCC cell lines CAL-27 and WSU-HN6 cells, probably by blocking cell cycle in the G1 phase. Furthermore, we revealed that Dlx5 exerts its biological functions via direct regulation of CCND1 in CAL-27 and WSU-HN6 cells. Ultimately, we have demonstrated that silencing of Dlx5 inhibits the growth of xenograft tumors in vivo, and that Dlx5 affects the progression of OSCC both in vitro and in vivo via directly regulating CCND1, providing a potential diagnostic biomarker and therapeutic target for OSCC.

Role of lysosomes in physiological activities, diseases, and therapy

Long known as digestive organelles, lysosomes have now emerged as multifaceted centers responsible for degradation, nutrient sensing, and immunity. Growing evidence also implicates role of lysosome-related mechanisms in pathologic process. In this review, we discuss physiological function of lysosomes and, more importantly, how the homeostasis of lysosomes is disrupted in several diseases, including atherosclerosis, neurodegenerative diseases, autoimmune disorders, pancreatitis, lysosomal storage disorders, and malignant tumors. In atherosclerosis and Gaucher disease, dysfunction of lysosomes changes cytokine secretion from macrophages, partially through inflammasome activation. In neurodegenerative diseases, defect autophagy facilitates accumulation of toxic protein and dysfunctional organelles leading to neuron death. Lysosomal dysfunction has been demonstrated in pathology of pancreatitis. Abnormal autophagy activation or inhibition has been revealed in autoimmune disorders. In tumor microenvironment, malignant phenotypes, including tumorigenesis, growth regulation, invasion, drug resistance, and radiotherapy resistance, of tumor cells and behaviors of tumor-associated macrophages, fibroblasts, dendritic cells, and T cells are also mediated by lysosomes. Based on these findings, a series of therapeutic methods targeting lysosomal proteins and processes have been developed from bench to bedside. In a word, present researches corroborate lysosomes to be pivotal organelles for understanding pathology of atherosclerosis, neurodegenerative diseases, autoimmune disorders, pancreatitis, and lysosomal storage disorders, and malignant tumors and developing novel therapeutic strategies.

Cathepsin K (Clone EPR19992) Demonstrates Uniformly Positive Immunoreactivity in Renal Oncocytoma, Chromophobe Renal Cell Carcinoma, and Distal Tubules

Introduction. Cathepsin K is overexpressed in several tumors associated with microphthalmia transcription factor (MiTF) family or mechanistic target of rapamycin (mTOR) upregulation. Among renal neoplasms, MiTF translocation renal cell carcinoma (RCC), perivascular epithelioid cell neoplasms (PEComa), and eosinophilic solid and cystic RCC have demonstrated Cathepsin K immunoreactivity. In this study, we demonstrate a uniform Cathepsin K expression in oncocytoma, chromophobe RCC (CHRCC), and distal tubules. Design. We stained 13 oncocytomas, 13 CHRCC, 14 clear cell RCC (CCRCC), 9 papillary RCC (PRCC), 9 PEComas, and 5 MiTF RCC. Additionally, we assessed immunoreactivity for Cathepsin K in non-neoplastic renal parenchyma. Immunolabeling was performed on regularly charged slides from formalin-fixed paraffin-embedded tissue with monoclonal anti-rabbit antibodies to human Cathepsin K (clone EPR19992, Abcam). Results. All oncocytomas demonstrated diffuse strong cytoplasmic immunolabeling. CHRCC demonstrated uniform less intense immunolabeling in all cases with membranous accentuation. The assessment of the non-neoplastic renal parenchyma in all cases showed strong cytoplasmic immunoreaction in distal tubules and proximal tubules stained faintly. Mesangial cells were not immunoreactive. All MiTF RCC and PEComas were immunoreactive for Cathepsin K, whereas CCRCC and PRCC were negative in all cases. Conclusions. In this study, we expand the spectrum of renal neoplasms reactive with a particular clone of Cathepsin K (EPR19992). Distal tubules are strongly immunoreactive for Cathepsin K. Our conclusions need to be taken into consideration when differential diagnosis includes MiTF RCC or PEComa and this Cathepsin K clone is included in the immunohistochemical panel. This newer antibody clone was not tested in prior publications, potentially explaining the difference in conclusions.

Expression of cathepsins B, D and K in thymic epithelial tumours

AIM

Cathepsins are proteases that regulate a wide range of physiological processes, including protein turnover, cell signalling and antigen presentation. Recent studies have shown that cathepsins are highly upregulated in many types of tumours. Of the 15 cathepsins in humans, cathepsins V and S are abundantly expressed in the thymus, and we previously showed that the immunostaining of these cathepsins could serve as diagnostic markers for thymic epithelial tumours. However, little is known about the expression of other cathepsins in thymic epithelial tumours. To determine the diagnostic implications of cathepsins, we performed immunohistochemical analysis of cathepsin B (CTB), cathepsin D (CTD) and cathepsin K (CTK), all of which have been reported to correlate with the progression of squamous cell carcinoma.

METHODS

The association between cathepsin expression and clinicopathological features was evaluated in 122 cases of thymoma and thymic carcinoma.

RESULTS

CTB and CTD were frequently expressed in type A and type AB thymomas. In contrast, CTB and CTD were significantly less common in type B thymomas than in type A or AB thymomas. In type AB thymomas, the expression of CTB correlated with histological features, and was found predominantly in the type A component. Notably, CTK was expressed most commonly in thymic carcinomas, and patients who died of the disease showed increased expression of CTK.

CONCLUSIONS

The expression of CTB and CTD correlated with the histological subtype of thymoma. In addition, the expression of CTK appears to be useful for the diagnosis of thymic carcinomas and as a prognostic marker.

Could CTSK and COL4A2 be specific biomarkers of poor prognosis for patients with gastric cancer in Asia?-a microarray analysis based on regional population

Background

In the purpose of identifying reliable biomarkers for evaluating prognosis, monitoring recurrence and exploring new therapeutic targets, it is quite necessary to screen for the genetic changes and potential molecular mechanisms of the occurrence and development of gastric cancer (GC) from the aspects of race and region.

Methods

Target datasets were retrieved from Gene Expression Omnibus (GEO) database with "gastric cancer" as the key word, and corresponding data was downloaded. The differentially expressed genes (DEGs) were obtained by using limma R package, and the Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway for DEGs were analyzed in Enirchr database. Protein-protein interaction (PPI) network and molecular module were also constructed through STRING database and Cytoscape software. Survival analyses were completed for DEGs in GEO and Kaplan-Meier plotter database via cross validation. Finally, the correlation between gene expression and the infiltration cell levels in tumor microenvironment (TME) was explored based on the tumor immune estimation resource (TIMER) database.

Results

Five GC-related microarray datasets were selected and used for differential analysis, and 222 DEGs were identified. GO analyses of DEGs were mainly involved in cell metabolism and the formation of extracellular matrix (ECM). The top enriched pathways of DEGs were protein digestion and absorption, ECM-receptor interaction, focal adhesion (FA), PI3K-Akt signaling pathway. Survival analyses of DEGs revealed that the expression levels of CTSK and COL4A2 were significantly associated with poor prognosis of GC patients in Asian. Specifically, the high expression of CTSK had a closely related to the infiltration level of inflammatory cell in TME.

Conclusions

CTSK and COL4A2 could play a critical role in the pathogenesis of GC and act as the promising prognostic biomarkers. CTSK could induce the formation of immunosuppressive TME and promote the immune escape of GC cells.

Prognostic role and therapeutic susceptibility of cathepsin in various types of solid tumor and leukemia: A systematic review

Cathepsins (CTSs) are multifunctional proteins that can play prominent roles in cancer progression and metastasis. In this systematic review, we compared the prognosis of CTS subtypes overexpression in leukemia and solid tumors, and investigated the effect of different factors on CTS prognosis. We systematically searched published articles indexed in PubMed, Scopus, Cochrane library, ISI Web of Science, and EmBase databases from February 2000 until January 2020. Among the selected leukemia and solid tumors studies, overexpression of CTS subtypes in newly diagnosed and treated patients were with poor prognosis in 43 studies (79.6%) and with good prognosis in 9 studies (16.6%). However, there were 2 studies (3.8%) with either good or poor prognosis, depending on conditions and caner stage and host cell. The relation between CTS and human leukocyte antigen (HLA) in leukemia and solid tumors was mentioned in 7 studies (13%). Overexpression of CTS subtypes in all new case patients had contributed to the induction of poor prognosis. It seems that CTS subtypes, based on the type of cancer and its stage, the type of host cells, and the probable relation with HLA, breed good or poor prognosis in patients with cancer. Therefore, monitoring the overexpression of CTS subtypes and determining the effect of each of these factors on CTS prognosis could be helpful in predicting cancer prognosis both in newly diagnosed or under treatment patients. They could also be useful in finding ways for improving the efficiency of contemporary therapeutic strategies in various types of leukemia and solid tumors.

Cathepsin K: The Action in and Beyond Bone

Cathepsin K (CatK) is one of the most potent proteases in lysosomal cysteine proteases family, of which main function is to mediate bone resorption. Currently, CatK is among the most attractive targets for anti-osteoporosis drug development. Although many pharmaceutical companies are working on the development of selective inhibitors for CatK, there is no FDA approved drug till now. Odanacatib (ODN) developed by Merck & Co. is the only CatK inhibitor candidate which demonstrated high therapeutic efficacy in patients with postmenopausal osteoporosis in Phase III clinical trials. Unfortunately, the development of ODN was finally terminated due to the cardio-cerebrovascular adverse effects. Therefore, it arouses concerns on the undesirable CatK inhibition in non-bone sites. It is known that CatK has far-reaching actions throughout various organs besides bone. Many studies have also demonstrated the involvement of CatK in various diseases beyond the musculoskeletal system. This review not only summarized the functional roles of CatK in bone and beyond bone, but also discussed the potential relevance of the CatK action beyond bone to the adverse effects of inhibiting CatK in non-bone sites.

Oncogenic effects of germline variants in lysosomal storage disease genes

PURPOSE

Clinical and experimental evidence has suggested pathobiological crosstalk between lysosomal storage diseases (LSDs) and cancer. We aimed to elucidate the association between germline variants in LSD genes and cancer.

METHODS

We performed aggregate rare variant association analysis of potentially pathogenic variants (PPVs) in 42 LSD genes and >30 histological types of cancer using genome sequencing data from 2567 cancer patients (Pan-Cancer cohort) and 2504 healthy individuals (1000 Genomes cohort) and exome sequencing data from 53,105 individuals without cancer (ExAC cohort).

RESULTS

PPVs were significantly enriched in the Pan-Cancer cohort compared with the 1000 Genomes cohort (PPV prevalence, 20.7% vs. 13.5%; P = 8.7 × 10^-12). Cancer risk was higher in individuals with a greater number of PPVs (P = 7.3 × 10^-12). Population structure-adjusted optimal sequence kernel association test (SKAT-O) revealed 37 significantly associated cancer type-LSD gene pairs. These results were supported by the consistent tendency toward enrichment of PPVs in cancer patients compared with the ExAC cohort. Cancer developed earlier in PPV carriers than in wild-type patients. Analysis of tumor transcriptomic data from the pancreatic adenocarcinoma cohort revealed 508 genes differentially expressed according to PPV carrier status, which were highly enriched in the core signaling pathways of pancreatic cancer.

CONCLUSION

Carriers of PPVs in LSD genes are at increased risk of cancer.

MITF Regulates Downstream Genes in Response to Vibrio parahaemolyticus Infection in the Clam Meretrix Petechialis

The microphthalmia-associated transcription factor (MITF) is a basic helix-loop-helix-leucine zipper protein that plays a key role in cell proliferation, survival and immune defense through the direct transcriptional control of downstream genes. We have found that MITF participates in the immune response to Vibrio parahaemolyticus infection in the clam Meretrix petechialis. In this study, we focused on how MITF functions in immunity. First, PO, CTSK, and BCL-2 were identified as the target genes of MpMITF in the clam by RNAi. EMSAs showed direct binding between the MpMITF protein and the E-box of the MpPO, MpCTSK, and MpBCL-2 promoters. Yeast one-hybrid assays also suggested that MpMITF could activate the expression of these three downstream genes. These results demonstrated that the transcriptional expression of MpPO, MpCTSK, and MpBCL-2 is directly regulated by MpMITF. Second, we analyzed the roles of MpPO, MpCTSK, and MpBCL-2 in clam immunity. The mRNA expression of MpPO, MpCTSK, and MpBCL-2 increased significantly after V. parahaemolyticus challenge, which implied that these genes might take part in the immune defense against V. parahaemolyticus challenge in clams. The purified recombinant proteins, MpPO and MpCTSK, inhibited the growth of V. parahaemolyticus. Additionally, the apoptosis rate of clam haemocytes rose significantly when the activity of MpBCL-2 was suppressed. These results revealed that MpPO, MpCTSK, and MpBCL-2 are involved in the immune defense against V. parahaemolyticus. This study supports the idea that the MpMITF pathway plays a key role in immune defense through the direct regulation of the downstream genes MpPO, MpCTSK, and MpBCL-2 in the clam, M. petechialis.

Association of autoimmunity and cancer: An emphasis on proteolytic enzymes

Cancer and autoimmune diseases are the two devastating conditions that together constitute a leading health problem worldwide. The rising burden of these disorders in the developing world demands a multifaceted approach to address the challenges it poses. Understanding the root causes and specific molecular mechanisms by which the progression of the diseases takes place is need of the hour. A strong inflammatory background and common developmental pathways, such as activation of immune cells, proliferation, increased cell survival and migration which are controlled by growth factors and inflammatory cytokines have been considered as the critical culprits in the progression and complications of these disorders. Enzymes are the potential immune modulators which regulate various inflammatory events and can break the circulating immune complexes via macrophages production. In the current manuscript, we have uncovered the possible role of proteolytic enzymes in the pathogenesis and progression of cancer and autoimmune diseases. In the light of the available scientific literature, we advocate in-depth comprehensive studies which will shed light towards the role of proteolytic enzymes in the modulation of inflammatory responses in cancer and autoimmune diseases together.

Gut microbiota-stimulated cathepsin K secretion mediates TLR4-dependent M2 macrophage polarization and promotes tumor metastasis in colorectal cancer

Metastasis is a complex process that requires the interaction between tumor cells and their microenvironment. As an important regulator of intestinal microenvironment, gut microbiota plays a significant role in the initiation and progression of colorectal cancer (CRC), but the underlying mechanisms remain elusive. In this study, a metastasis-related secretory protein cathepsin K (CTSK) was identified as a vital mediator between the imbalance of intestinal microbiota and CRC metastasis. We implanted MC38 cells into the cecal mesentry of antibiotic-treated mice with intragastrically administration of E. coli to mimic gut microbiota imbalance. The bigger primary tumors and more liver metastatic foci were detected in the E. coli group accompanied with high LPS secretion and CTSK overexpression compared with that in the control group. CTSK contributes to the aggressive phenotype of CRC cells both in vitro and in vivo. Silencing CTSK or administration of Odanacatib, a CTSK-specific inhibitor, totally abolished the CTSK-enhanced migration and motility of CRC cells. Interestingly, the tumor-secreted CTSK could bind to toll-like receptor 4 (TLR4) to stimulate the M2 polarization of tumor-associated macrophages (TAMs) via an mTOR-dependent pathway. Recombinant CTSK could neither stimulate CRC growth and metastasis, nor induce M2 macrophage polarization in TRL4^-/- mice. Meanwhile, CTSK could stimulate the secretion of cytokines by M2 TAMs including IL10 and IL17, which, in turn, promote the invasion and metastasis of CRC cells through NFκB pathway. Clinically, overexpression of CTSK in human CRC tissues is always accompanied with high M2 TAMs in the stroma, and correlated with CRC metastasis and poor prognosis. Our current research identified CTSK as a mediator between the imbalance of gut microbiota and CRC metastasis. More importantly, we illustrated a CTSK-mediated-positive feedback loop between CRC cells and TAMs during metastasis, prompting CTSK as a novel predictive biomarker and feasible therapeutic target for CRC.

Cathepsins: Potent regulators in carcinogenesis

Cathepsins (CTS) are mainly lysosomal acid hydrolases extensively involved in the prognosis of different diseases, and having a distinct role in tumor progression by regulating cell proliferation, autophagy, angiogenesis, invasion, and metastasis. As all these processes conjunctively lead to cancer progression, their site-specific regulation might be beneficial for cancer treatment. CTS regulate activation of the proteolytic cascade and protein turnover, while extracellular CTS is involved in promoting extracellular matrix degradation and angiogenesis, thereby stimulating invasion and metastasis. Despite cancer regulation, the involvement of CTS in cellular adaptation toward chemotherapy and radiotherapy augments their therapeutic potential. However, lysosomal permeabilization mediated cytosolic translocation of CTS induces programmed cell death. This complex behavior of CTS generates the need to discuss the different aspects of CTS associated with cancer regulation. In this review, we mainly focused on the significance of each cathepsin in cancer signaling and their targeting which would provide noteworthy information in the context of cancer biology and therapeutics.

Cathepsin B inhibition ameliorates the non-alcoholic steatohepatitis through suppressing caspase-1 activation

Non-alcoholic fatty liver disease (NAFLD) has emerged as the most common chronic liver disease. NLRP3 inflammasome activation has been widely studied in the pathogenesis of NAFLD. Cathepsin B (CTSB) is a ubiquitous cysteine cathepsin, and the role of CTSB in the progression and development of NAFLD has received extensive concern. However, the exact roles of CTSB in the NAFLD development and NLRP3 inflammasome activation are yet to be evaluated. In the present study, we used methionine choline-deficient (MCD) diet to establish mice NASH model. CTSB inhibitor (CA-074) was used to suppress the expression of CSTB. Expressions of CTSB and caspase-1 were evaluated by immunohistochemical staining. Serum IL-1β and IL-18 levels were also determined. Palmitic acid was used to stimulate Kupffer cells (KCs), and protein expressions of CTSB, NLRP3, ASC (apoptosis-associated speck-like protein containing CARD), and caspase-1 in KCs were detected. The levels of IL-1β and IL-18 in the supernatant of KCs were evaluated by enzyme-linked immunosorbent assay (ELISA). Our results showed that CTSB inhibition improved the liver function and reduced hepatic inflammation and ballooning, and the levels of pro-inflammatory cytokines IL-1β and IL-18 were decreased. The expressions of CTSB and caspase-1 in liver tissues were increased in the NASH group. In in vitro experiments, PA stimulation could increase the expressions of CTSB and NLRP3 inflammasome in KCs, and CTSB inhibition downregulated the expression of NLRP3 inflammasome in KCs, when challenged by PA. Moreover, CTSB inhibition effectively suppressed the expression and activity of caspase-1 and subsequently secretions of IL-1β and IL-18. Collectively, these results suggest that CTSB inhibition limits NLRP3 inflammasome-dependent NASH formation through regulating the expression and activity of caspase-1, thus providing a novel anti-inflammatory signal pathway for the therapy of NAFLD.