Cathepsin S in tumours, regional lymph nodes and sera of patients with lung cancer: relation to prognosis

Roles of cathepsin S expression levels on the prognosis and tumour microenvironment in clear cell renal cell carcinoma

BACKGROUND

Increasing evidence suggests a link between the enzyme cathepsin S (CTSS) and tumour development. However, the potential involvement and molecular functions of CTSS in clear cell renal cell carcinoma (ccRCC) remain unclear.

METHODS

We downloaded original data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases and integrated them using R. Kaplan-Meier plots of integrated expression scores were used to analyse survival outcomes. Additionally, we investigated mRNA expression, clinicopathological features, immune infiltrates, and single-cell sequencing analysis of CTSS in ccRCC. In vitro experiments were conducted with qRT-PCR and IHC staining.

RESULTS

CTSS transcriptomic and proteomic levels were higher in ccRCC than in para-cancerous tissues. Low CTSS expression was correlated with poor prognosis in patients with ccRCC. Our data demonstrated that the expression of CTSS was strongly correlated with immune cell infiltration levels and gene markers of immune cells, chemokines, and receptors. Single-cell sequencing analysis demonstrated that CTSS expression was detectable in monocytes/macrophages. Finally, certain chemicals were confirmed to affect CTSS expression.

CONCLUSION

Our findings indicate that CTSS offers promise as a prognostic biomarker and novel immune-related therapeutic target for ccRCC.

Cysteine cathepsins: From diagnosis to targeted therapy of cancer

Cysteine cathepsins are a fascinating group of proteolytic enzymes that play diverse and crucial roles in numerous biological processes, both in health and disease. Understanding these proteases is essential for uncovering novel insights into the underlying mechanisms of a wide range of disorders, such as cancer. Cysteine cathepsins influence cancer biology by participating in processes such as extracellular matrix degradation, angiogenesis, immune evasion, and apoptosis. In this comprehensive review, we explore foundational research that illuminates the diverse and intricate roles of cysteine cathepsins as diagnostic markers and therapeutic targets for cancer. This review aims to provide valuable insights into the clinical relevance of cysteine cathepsins and explore their capacity to advance personalised and targeted medical interventions in oncology.

Advances in Cathepsin S Inhibition: Challenges and Breakthroughs in Drug Development

Cathepsin S (CatS) is a proteolytic enzyme and a member of the cysteine protease family of proteolytic enzymes. Cathepsins S, K, and L are particularly similar in terms of their amino acid sequences and interactions with substrates, and this has made it difficult to develop inhibitors with specificity for either CatS, CatK, or CatL. The involvement of CatS in various disease pathophysiologies (autoimmune disorders, cardiovascular diseases, cancer, etc.) has made it a very important target in drug development. Efforts have been made since the early 1990s to develop a specific CatS inhibitor without any major success. Following many failed efforts to develop an inhibitor for CatS, it was discovered that interactions with the amino acid residues at the S2 and S3 pockets of CatS are critical for the identification of CatS-specific inhibitors. Amino acid residues at these pockets have been the target of recent research focused on developing a non-covalent, reversible, and specific CatS inhibitor. Methods applied in the identification of CatS inhibitors include molecular modeling, in-vitro screening, and in-vivo studies. The molecular modeling process has proven to be very successful in the identification of CatS-specific inhibitors, with R05459072 (Hoffmann-La Roche) and LY3000328 (Eli Lilly Company) which has completed phase 1 clinical trials. CatS inhibitors identified from 2011 to 2023 with promising prospects are discussed in this article.

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.

Mendelian randomization analyses explore the relationship between cathepsins and lung cancer

Lung cancer, a major contributor to cancer-related fatalities worldwide, involves a complex pathogenesis. Cathepsins, lysosomal cysteine proteases, play roles in various physiological and pathological processes, including tumorigenesis. Observational studies have suggested an association between cathepsins and lung cancer. However, the causal link between the cathepsin family and lung cancer remains undetermined. This study employed Mendelian randomization analyses to investigate this causal association. The univariable Mendelian randomization analysis results indicate that elevated cathepsin H levels increase the overall risk of lung cancer, adenocarcinoma, and lung cancer among smokers. Conversely, reverse Mendelian randomization analyses suggest that squamous carcinoma may lead to increased cathepsin B levels. A multivariable analysis using nine cathepsins as covariates reveals that elevated cathepsin H levels lead to an increased overall risk of lung cancer, adenocarcinoma, and lung cancer in smokers. In conclusion, cathepsin H may serve as a marker for lung cancer, potentially inspiring directions in lung cancer diagnosis and treatment.

Cysteine Cathepsins as Therapeutic Targets in Immune Regulation and Immune Disorders

Cysteine cathepsins, as the most abundant proteases found in the lysosomes, play a vital role in several processes-such as protein degradation, changes in cell signaling, cell morphology, migration and proliferation, and energy metabolism. In addition to their lysosomal function, they are also secreted and may remain functional in the extracellular space. Upregulation of cathepsin expression is associated with several pathological conditions including cancer, neurodegeneration, and immune-system dysregulation. In this review, we present an overview of cysteine-cathepsin involvement and possible targeting options for mitigation of aberrant function in immune disorders such as inflammation, autoimmune diseases, and immune response in cancer.

Cathepsin S Evokes PAR2-Dependent Pain in Oral Squamous Cell Carcinoma Patients and Preclinical Mouse Models

Oral squamous cell carcinoma (SCC) pain is more prevalent and severe than pain generated by any other form of cancer. We previously showed that protease-activated receptor-2 (PAR2) contributes to oral SCC pain. Cathepsin S is a lysosomal cysteine protease released during injury and disease that can activate PAR2. We report here a role for cathepsin S in PAR2-dependent cancer pain. We report that cathepsin S was more active in human oral SCC than matched normal tissue, and in an orthotopic xenograft tongue cancer model than normal tongue. The multiplex immunolocalization of cathepsin S in human oral cancers suggests that carcinoma and macrophages generate cathepsin S in the oral cancer microenvironment. After cheek or paw injection, cathepsin S evoked nociception in wild-type mice but not in mice lacking PAR2 in Nav1.8-positive neurons (Par2Nav1.8), nor in mice treated with LY3000328 or an endogenous cathepsin S inhibitor (cystatin C). The human oral SCC cell line (HSC-3) with homozygous deletion of the gene for cathepsin S (CTSS) with CRISPR/Cas9 provoked significantly less mechanical allodynia and thermal hyperalgesia, as did those treated with LY3000328, compared to the control cancer mice. Our results indicate that cathepsin S is activated in oral SCC, and that cathepsin S contributes to cancer pain through PAR2 on neurons.

An Immunosensor for the Determination of Cathepsin S in Blood Plasma by Array SPRi-A Comparison of Analytical Properties of Silver-Gold and Pure Gold Chips

The array SPR imaging (SPRi) technique is well suited to the determination of biomarkers in body fluids, called liquid biopsy. No signal enhancement or analyte preconcentration is required. With the aim of achieving signal enhancement and lowering the cost of a single determination, the replacement of gold-covered chips by silver–gold chips was investigated. The aim of this work was to investigate the analytical characteristics of a biosensor formed on a Ag/Au chip and to compare them with those of a biosensor formed on a gold chip. A biosensor for the determination of cathepsin S (Cath S) was chosen as an example. The biosensor consisted of the linker cysteamine and an immobilized rat monoclonal antibody specific for cathepsin S. Both biosensors exhibited a Langmuirian response to Cath S concentration, with linear response ranging from LOQ to 1.5 ng mL⁻¹. The LOQ is 0.1 ng mL⁻¹ for the biosensor formed on the Ag/Au chip, and 0.22 ng mL⁻¹ for that formed on the gold chip. Recoveries and precision for medium and high Cath S concentrations were acceptable for both biosensors, i.e., precision better than 10% and recoveries within the range 102–105%. However, the results for the lowest Cath S concentration were better for the biosensor formed on the Ag/Au chip (9.4 and 106% for precision and recovery, respectively). Generally, no significant differences in analytical characteristics were observed between the Ag/Au and Au chips. The two biosensors were also compared in the determination of Cath S in real samples. Nine plasma samples from healthy donors and nine from patients with ovarian cancer were analyzed for Cath S concentration with the biosensors formed on Ag/Au and Au chips. The results obtained with the two biosensors were very similar and show no significant differences on the Bland–Altman plot. The Cath S concentration in the blood plasma of ovarian cancer patients was elevated by one order of magnitude as compared with the control (12.6 ± 3.6 vs. 1.6 ± 1.2 ng mL⁻¹).

Two SPRi biosensors for the determination of cathepsin S in blood plasma

Cathepsin S is an emerging marker for ovarian cancer. Two 'analytically specific' SPRi biosensors for the determination of Cath S have been developed. The reception part of one of the biosensors consists of the rat monoclonal antibody specific for cathepsin S attached to the gold surface via covalent bonds with cysteamine linker, while the second biosensor consists of the inhibitor LY3000328 attached via hydrophobic interaction with the 1-octadecanothiol linker. Under optimized conditions, in terms of pH and receptor concentration, both biosensors have linear response ranges between LOQ (0.14 ng mL^-1) and 2.5 ng mL^-1, which is suitable for the determination of Cath S in blood plasma samples of ovarian cancer patients and healthy individuals, after corresponding dilution with 0.15 M PBS buffer. Precision and recoveries are quite acceptable: below 7% and 98-101% respectively for the biosensor with antibody, and below 12% and 101-103% for the biosensor with inhibitor. The biosensors were validated by the determination of Cath S in series of plasma from ovarian cancer patients and healthy volunteers using both biosensors and ELISA, giving Pearson coefficients close to 1. Plasma Cath S concentration can be used as an ovarian cancer marker, in view of the highly elevated concentrations detected.

The P2X7 purinergic receptor: a potential therapeutic target for lung cancer

PURPOSE

Purinergic P2X7 receptor (P2X7R) is a gated ion channel for which adenosine triphosphate (ATP) is a ligand. Activated P2X7R is widely expressed in a variety of immune cells and tissues and is involved in a variety of physiological and pathological processes. Studies have confirmed that P2X7R is involved in the regulation of tumor cell growth, stimulating cell proliferation or inducing apoptosis. Recent studies have found that P2X7R is abnormally expressed in lung cancer and is closely related to the carcinogenesis and development of lung cancer. In this paper, we comprehensively describe the structure, function, and genetic polymorphisms of P2X7R. In particular, the role and therapeutic potential of P2X7R in lung cancer are discussed to provide new targets and new strategies for the treatment and prognosis of clinical lung cancer.

METHODS

The relevant literature on P2X7R and lung cancer from PubMed databases is reviewed in this article.

RESULTS

P2X7R regulates the function of lung cancer cells by activating multiple intracellular signaling pathways (such as the JNK, Rho, HMGB1 and EMT pathways), thereby affecting cell survival, growth, invasion, and metastasis and patient prognosis. Targeting P2X7R with inhibitors effectively suppresses the growth and metastasis of lung cancer cells.

CONCLUSION

In summary, P2X7R is expected to become a potential target for the treatment of lung cancer, and more clinical research is needed in the future to explore the effectiveness of P2X7R antagonists as treatments.

Ab locks for improving the selectivity and safety of antibody drugs

Monoclonal antibodies (mAbs) are a major targeted therapy for malignancies, infectious diseases, autoimmune diseases, transplant rejection and chronic inflammatory diseases due to their antigen specificity and longer half-life than conventional drugs. However, long-term systemic antigen neutralization by mAbs may cause severe adverse events. Improving the selectivity of mAbs to distinguish target antigens at the disease site from normal healthy tissue and reducing severe adverse events caused by the mechanisms-of-action of mAbs is still a pressing need. Development of pro-antibodies (pro-Abs) by installing a protease-cleavable Ab lock is a novel and advanced recombinant Ab-based strategy that efficiently masks the antigen binding ability of mAbs in the normal state and selectively "turns on" the mAb activity when the pro-Ab reaches the proteolytic protease-overexpressed diseased tissue. In this review, we discuss the design and advantages/disadvantages of different Ab lock strategies, focusing particularly on spatial-hindrance-based and affinity peptide-based approaches. We expect that the development of different masking strategies for mAbs will benefit the local reactivity of mAbs at the disease site, increase the therapeutic efficacy and safety of long-term treatment with mAbs in chronic diseases and even permit scientists to develop Ab drugs for formerly undruggable targets and satisfy the unmet medical needs of mAb therapy.

Leading the invasion: The role of Cathepsin S in the tumour microenvironment

Elevated expression of the cysteine protease Cathepsin S has been correlated with a number of different cancer types in recent years. As tools have been developed to enable more accurate examination of individual cathepsin species, our knowledge and appreciation of the role that this protease plays in facilitating cancer has increased exponentially. This review focuses on our current understanding of the role of Cathepsin S within tumours and the surrounding microenvironment. While various publications have shown that Cathepsin S can be derived from tumour cells themselves, a plethora of more recent studies have identified that Cathepsin S can also be derived from other cell types within the tumour microenvironment including endothelial cells, macrophages and T cells. Furthermore, specific proteolytic substrates cleaved by Cathepsin S have also been identified which have reinforced our hypothesis that this protease facilitates key steps within tumours leading to their invasion, angiogenesis and metastasis.

Melatonin attenuates epidermal growth factor-induced cathepsin S expression in ARPE-19 cells: Implications for proliferative vitreoretinopathy

Abnormal proliferation and motility of retinal pigment epithelial cells leads to proliferative vitreoretinopathy (PVR). Melatonin is a known effective antitumour and anti-invasive agent, but whether it affects the formation and underlying mechanisms of PVR remains unclear. In this study, the results of the MTT assay, colony formation and propidium iodide (PI) staining with flow cytometry revealed that melatonin dose dependently inhibited epidermal growth factor (EGF)-induced proliferation of human ARPE-19 cells. Furthermore, melatonin reduced EGF-induced motility by suppressing cathepsin S (CTSS) expression. Pretreatment with ZFL (a CTSS inhibitor) or overexpression of CTSS (pCMV-CTSS) significantly inhibited EGF-induced cell motility when combined with melatonin. Epidermal growth factor induced the phosphorylation of AKT(S473)/mTOR (S2448) and transcription factor (c-Jun/Sp1) signaling pathways. Pretreatment of LY294002 (a PI3K inhibitor) or rapamycin (an mTOR inhibitor) markedly reduced EGF-induced motility and p-AKT/p-mTOR/c-Jun/Sp1 expression when combined with melatonin. Taken together, these data indicate that melatonin inhibited EGF-induced proliferation and motility of human ARPE-19 cells by activating the AKT/mTOR pathway, which is dependent on CTSS modulation of c-Jun/Sp1 signalling. Melatonin may be a promising therapeutic drug against PVR.

Cigarette smoke induces overexpression of active human cathepsin S in lungs from current smokers with or without COPD

Cigarette smoking has marked effects on lung tissue, including induction of oxidative stress, inflammatory cell recruitment, and a protease/antiprotease imbalance. These effects contribute to tissue remodeling and destruction resulting in loss of lung function in chronic obstructive pulmonary disease (COPD) patients. Cathepsin S (CatS) is a cysteine protease that is involved in the remodeling/degradation of connective tissue and basement membrane. Aberrant expression or activity of CatS has been implicated in a variety of diseases, including arthritis, cancer, cardiovascular, and lung diseases. However, little is known about the effect of cigarette smoking on both CatS expression and activity, as well as its role in smoking-related lung diseases. Here, we evaluated the expression and activity of human CatS in lung tissues from never-smokers and smokers with or without COPD. Despite the presence of an oxidizing environment, CatS expression and activity were significantly higher in current smokers (both non-COPD and COPD) compared with never-smokers, and correlated positively with smoking history. Moreover, we found that the exposure of primary human bronchial epithelial cells to cigarette smoke extract triggered the activation of P2X7 receptors, which in turns drives CatS upregulation. The present data suggest that excessive CatS expression and activity contribute, beside other proteases, to the deleterious effects of cigarette smoke on pulmonary homeostasis.

Plasma Cathepsin S is Associated with High-density Lipoprotein Cholesterol and Bilirubin in Patients with Abdominal Aortic Aneurysms

Background

Cathepsin S (CTSS) is a cysteine protease involved in atherogenesis. We compared the plasma CTSS as well as other biomarkers of atherosclerosis in patients with abdominal aortic aneurysms (AAA) and aortoiliac occlusive disease (AOD), aiming to identify the underlying pathogenic mechanisms of the disease development. Also, we hypothesised that the level of plasma CTSS simultaneously increases with a decrease of plasma high-density lipoprotein cholesterol (HDL-C) values.

Methods

33 patients with AAA and 34 patients with AOD were included in this study.

Results

There was no difference in the level of plasma CTSS between the two analysed groups (p=0.833). In the patients with AAA, the plasma CTSS was correlated with HDL-C (r = -0.377, p = 0.034) and total bilirubin (r =0.500, p = 0.003) while, unexpectedly, it was not correlated with cystatin C (Cys C) (r =0.083, p = 0.652). In the patients with AOD, the plasma CTSS correlated with triglycerides (r = 0.597, p< 0.001), only. When the patients were divided according to HDL-C (with HDL-C ≤0.90 and HDL-C >0.90 mmol/L), the plasma CTSS values differed among these groups (31.27 vs.25.61 μg/L, respectively, p<0.001).

Conclusions

These results provide the first evidence that CTSS negatively correlated with HDL-C and bilirubin in patients with AAA. It is possible that differences in the association of the CTSS and other markers of atherosclerosis can determine whether atherosclerotic aorta will develop dilatation or stenosis.

Application of nanotechnology to target and exploit tumour associated proteases

Proteases are hydrolytic enzymes fundamental for a variety of physiological processes, but the loss of their regulation leads to aberrant functions that promote onset and progression of many diseases including cancer. Proteases have been implicated in almost every hallmark of cancer and whilst widely investigated for tumour therapy, clinical adoption of protease inhibitors as drugs remains a challenge due to issues such as off-target toxicity and inability to achieve therapeutic doses at the disease site. Now, nanotechnology-based solutions and strategies are emerging to circumvent these issues. In this review, preclinical advances in approaches to enhance the delivery of protease drugs and the exploitation of tumour-derived protease activities to promote targeting of nanomedicine formulations is examined. Whilst this field is still in its infancy, innovations to date suggest that nanomedicine approaches to protease targeting or inhibition may hold much therapeutic and diagnostic potential.

Expression of Proteolytic Enzymes by Small Cell Lung Cancer Circulating Tumor Cell Lines

Small cell lung cancer (SCLC) is an aggressive type of lung cancer which disseminates vigorously and has a dismal prognosis. Metastasis of SCLC is linked to an extremely high number of circulating tumor cells (CTCs), which form chemoresistant spheroids, termed tumorospheres. Intravasation and extravasation during tumor spread requires the activity of a number of proteases to disintegrate the stroma and vascular tissue. Generation of several permanent SCLC CTC lines allowed us to screen for the expression of 35 proteases using Western blot arrays. Cell culture supernatants of two CTC lines, namely BHGc7 and 10, were analyzed for secreted proteases, including matrix metalloproteinases (MMPs), ADAM/TS, cathepsins, kallikreins, and others, and compared to proteases expressed by SCLC cell lines (GLC14, GLC16, NCI-H526 and SCLC26A). In contrast to NCI-H526 and SCLC26A, MMP-9 was highly expressed in the two CTC lines and in GLC16 derived of a relapse. Furthermore, cathepsins (S, V, X/Z/P, A and D) were highly expressed in the CTC lines, whereas ADAM/TS and kallikreins were not detectable. In conclusion, SCLC CTCs express MMP-9 and a range of cathepsins for proteolysis and, aside from tissue degradation, these enzymes are involved in cell signaling, survival, and the chemoresistance of tumor cells.

Z-FL-COCHO, a cathepsin S inhibitor, enhances oxaliplatin-mediated apoptosis through the induction of endoplasmic reticulum stress

Multiple cancer cells highly express cathepsin S, which has pro-tumoral effects. However, it was previously unknown whether knockdown or a pharmacological inhibitor (ZFL) of cathepsin S acts as an inducer of ER stress. Here, ZFL and knockdown of cathepsin S markedly induced ER stress through the up-regulation of calcium levels in the cytosol. Induction of calcium levels by inhibition of cathepsin S is markedly blocked by an inhibitor of the IP3 receptor and the ryanodine receptor Ca²⁺ channel in the ER, but an inhibitor of a mitochondrial Ca²⁺ uniporter had no effect on ZFL-induced calcium levels. Furthermore, production of mitochondrial ROS by ZFL was associated with an increase in cytosolic calcium levels. ZFL-mediated ER stress enhanced anti-cancer drug-induced apoptotic cell death, and pretreatment with chemical chaperones or down-regulation of ATF4 and CHOP by small interfering RNA markedly reduced ZFL plus oxaliplatin-induced apoptosis. Taken together, our findings reveal that inhibition of cathepsin S is an inducer of ER stress; these findings may contribute to the enhancement of therapeutic efficiency in cancer cells.

A drug that inhibits a key cancer enzyme could be used in combination with anti-cancer drugs to improve sensitivity to treatment. The intracellular endoplasmic reticulum (ER) is involved in several vital processes in cells, including folding and processing proteins. Taeg Kyu Kwon at Keimyung University, Daegu, South Korea, and co-workers have demonstrated how inhibition of cathepsin S, which is expressed in many cancer cells, induces ER stress. In trials on human kidney cancer cells grafted onto mice and in vitro, the team found that ZFL (cathepsin S inhibitor) triggered transient ER stress by increasing calcium levels inside cells. Subsequent treatment with the anti-cancer drug oxaliplatin resulted in increased cancer cell death.

The transcription factor C/EBP α controls the role of cystatin F during the differentiation of monocytes to macrophages

Cystatin F is an inhibitor of cysteine peptidases expressed solely in immune cells. It is the only type II cystatin able to enter endosomal/lysosomal vesicles and to regulate directly the activity of intracellular cysteine cathepsins. Its expression in promonocytic U937 and promyeloblastic HL-60 cells is highly upregulated but, after differentiation with phorbol 12-myristate 13-acetate - PMA, its levels drop significantly. In contrast, the activities of intracellular cysteine cathepsins C, L and S are higher in differentiated cells than in non-differentiated ones due, presumably, to the lower inhibitory capacity of cystatin F. Using immunofluorescence confocal microscopy, proximity ligation assay and co-immunoprecipitation, cathepsins C, L and S were confirmed to be the main interacting partners of cystatin F in U937 and HL-60 cells. The promoter region of the cystatin F gene, CST7, contains a unique binding site for transcription factor C/EBP α, one of the main myeloid differentiation instructors. Using the chromatin immunoprecipitation assay, C/EBP α was shown to bind to CST7 gene in U937 cells. Following cell differentiation with PMA, the binding of C/EBP α was decreased significantly. The protein level of C/EBP α was also significantly lower in differentiated than in non-differentiated cells. It was shown that, during monocyte to macrophage differentiation, the endosomal/lysosomal proteolytic activity can be regulated by cystatin F whose expression is under the control of transcriptional factor C/EBP α.

Regulating BRCA1 protein stability by cathepsin S-mediated ubiquitin degradation

Cathepsin S (CTSS) is a cysteine protease that is thought to play a role in many physiological and pathological processes including tumor growth, angiogenesis, and metastasis; it has been identified as a radiation response gene. Here, we examined the role of CTSS in regulating the DNA damage response in breast cancer cells. Activating CTSS (producing the cleavage form of the protein) by radiation induced proteolytic degradation of BRCA1, which ultimately suppressed DNA double-strand break repair activity. Depletion of CTSS by RNAi or expression of a mutant type of CTSS enhanced the protein stability of BRCA1 by inhibiting its ubiquitination. CTSS interacted with the BRCT domain of BRCA1 and facilitated ubiquitin-mediated proteolytic degradation of BRCA1, which was tightly associated with decreased BRCA1-mediated DNA repair activity. Treatment with a pharmacological CTSS inhibitor inhibited proteolytic degradation of BRCA1 and restored BRCA1 function. Depletion of CTSS by shRNA delayed tumor growth in a xenograft mouse model, only in the presence of functional BRCA1. Spontaneously uced rat mammary tumors and human breast cancer tissues with high levels of CTSS expression showed low BRCA1 expression. From these data, we suggest that CTSS inhibition is a good strategy for functional restoration of BRCA1 in breast cancers with reduced BRCA1 protein stability.

Integrated bioinformatics analysis reveals that the expression of cathepsin S is associated with lymph node metastasis and poor prognosis in papillary thyroid cancer

The prognosis of the majority of patients with papillary thyroid cancer (PTC) is excellent, although there are patients who experience disease recurrence and progression. The aim of the present study was to identify potential prognostic risk markers in PTC. Differentially expressed genes (DEGs), identified from four Genome Expression Omnibus cohorts were subjected to functional enrichment analyses with Gene Ontology terms and the Kyoto Encyclopedia of Genes and Genome pathways. Hub genes, filtered from cytoHubba, were validated using the The Cancer Genome Atlas (TCGA) cohort, and their associations with clinicopathological features and prognosis were analyzed. A total of 277 DEGs were identified following data preprocessing. DEGs were primarily enriched in 'small cell lung cancer', 'ECM-receptor interaction', 'pathways in cancer'and 'tyrosine metabolism'. Hub genes [APOE, cathepsin S (CTSS), insulin receptor substrate 1 (IRS1), KIT, LGALS3, RUNX2 and TGFBR1] were extracted from cytoHubba. Their expression in the TCGA cohort was consistent with that in the GEO cohorts. CTSS (P=0.006) and IRS1 (P=0.005) were associated with disease‑free survival, as determined using the Kaplan-Meier analysis. CTSS was an independent risk factor for poor disease‑free survival (HR, 2.649; 95% CI, 1.095-6.409; P=0.031). Patients with high expression of CTSS exhibited different histological types (increased tall-cell subtype and reduced follicular subtype; P<0.001), more frequent lymph node metastasis (P<0.001) and advanced tumor-node-metastasis stages (P=0.049) compared with the low-expression group. High expression of CTSS was independently associated with lymph node metastasis (OR, 2.015; 95% CI, 1.225-3.315; P=0.006). Therefore, CTSS may serve as a predictive risk marker for the progression and prognosis of PTC.

Cysteine cathepsins as a prospective target for anticancer therapies-current progress and prospects

Cysteine cathepsins (CTS), being involved in both physiological and pathological processes, play an important role in the human body. During the last 30 years, it has been shown that CTS are highly upregulated in a wide variety of cancer types although they have received a little attention as a potential therapeutic target as compared to serine or metalloproteinases. Studies on the increasing problem of neoplastic progression have revealed that secretion of cell-surface- and intracellular cysteine proteases is aberrant in tumor cells and has an impact on their growth, invasion, and metastasis by taking part in tumor angiogenesis, in apoptosis, and in events of inflammatory and immune responses. Considering the role of CTS in carcinogenesis, inhibition of these enzymes becomes an attractive strategy for cancer therapy. The downregulation of natural CTS inhibitors (CTSsis), such as cystatins, observed in various types of cancer, supports this claim. The intention of this review is to highlight the relationship of CTS with cancer and to present illustrations that explain how some of their inhibitors affect processes related to neoplastic progression.

Sulforaphane suppresses oral cancer cell migration by regulating cathepsin S expression

Sulforaphane has been demonstrated to exert numerous biological effects, such as neuroprotective, anti-inflammatory, and anticancer effects. However, the detailed effects of sulforaphane on human oral cancer cell migration and the underlying mechanisms remain unclear. In this study, we observed that sulforaphane attenuated SCC-9 and SCC-14 cell motility and invasiveness by reducing cathepsin S expression. Moreover, sulforaphane increased microtubule-associated protein 1 light chain 3 (LC3) conversion, and the knockdown of LC3 by siRNA increased cell migration ability. Regarding the mechanism, sulforaphane inhibited the cell motility of oral cancer cells through the extracellular signal-regulated kinase (ERK) pathway, which in turn reversed cell motility. In conclusion, sulforaphane suppress cathepsin S expression by inducing autophage through ERK signaling pathway. Thus, cathepsin S and LC3 may be new targets for oral cancer treatment.

Levels of Cathepsins S and H in Pleural Fluids of Inflammatory and Neoplastic Origin

Cathepsins S and H are present in immune cells and tissues and may play a role in the activation of an adoptive immune response. Our goal was to assess their protein levels in pleural fluids from 82 patients who underwent thoracentesis or thoracoscopy for therapeutic or diagnostic reasons and to relate them to an inflammatory, neoplastic or hemodynamic origin. Pleural effusions were also analyzed for a panel of 13 inflammatory or proliferative markers to test possible links to a nonspecific host reaction. Increased levels of cathepsin S were found in parainflammatory and cancer-related effusions compared to transudates. Cathepsin H levels were elevated only in parainflammatory effusions, whereas the levels in cancer-related effusions were comparable to transudates. Cathepsin S values significantly correlated with LDH, alpha-1-AT, VEGF, sICAM, sVCAM, MPO, uPA, MMP-9/TIMP-1, IL-8 and MCP-1, but not with CRP, IL-10 or cathepsin H. In contrast to cathepsin S, cathepsin H values did not correlate with markers of inflammation, indicating a specific role for cathepsin H in the pleural host response. In conclusion, the estimation of cathepsin S and cathepsin H may help to distinguish between effusions of different etiology.

Evaluating the diagnostic and prognostic value of circulating cathepsin S in gastric cancer

To evaluate whether serum Cathepsin S (Cat S) could serve as a biomarker for the diagnosis and prognosis of gastric cancer (GC), Enzyme-linked immuno sorbent assay (ELISA) was used to detect serum Cat S in 496 participants including healthy controls and patients with benign gastric diseases, gastric cancer, esophageal cancer, liver cancer, colorectal cancer, nasopharyngeal cancer and lung cancer. The levels of serum Cat S were significantly increased in cancer patients, especially in GC patients. The qRT-PCR, Western blotting, and immunohistochemical staining revealed the overexpression of Cat S in GC cell lines and tissues. The diagnostic value of serum Cat S for GC patients from controls resulted in an AUC of 0.803 with a sensitivity of 60.7% and a specificity of 90.0%. Moreover, the levels of serum Cat S were associated with GC tumor volume, lymphoid nodal status, metastasis status, and stages. Moreover, the patients with high levels of serum Cat S had a poorer overall survival. Univariate analysis revealed Cat S expression was a prognostic factor. The knockdown of Cat S significantly suppressed the migration and invasion of GC cells. This study suggested serum Cat S may be a potential biomarker for the diagnosis and prognosis of GC.

Inhibition of cathepsin S confers sensitivity to methyl protodioscin in oral cancer cells via activation of p38 MAPK/JNK signaling pathways

Oral cancer is one of the most common cancers in the world. Approximately 90% of oral cancers are subtyped to oral squamous cell carcinoma (OSCC). Despite advances in diagnostic techniques and improvement in treatment modalities, the prognosis remains poor. Therefore, an effective chemotherapy mechanism that enhances tumor sensitivity to chemotherapeutics is urgently needed. Methyl protodioscin (MP) is a furostanol bisglycoside with a wide range of beneficial effects, including anti-inflammatory and anti-cancer properties. The aim of the present study was to determine the antitumor activity of MP on OSCC and its underlying mechanisms. Our results show that treatment of OSCC cells with MP potently inhibited cell viability. Moreover, MP leading to cell cycle arrest at G2/M phase, which subsequently activates caspase-3, -8, -9 and PARP to induce cell apoptosis. Meanwhile, we also demonstrate that MP induces a robust autophagy in OSCC cells. The results indicate cathepsin S (CTSS) is involved in MP-induced apoptosis and autophagy by modulation of p38 MAPK and JNK1/2 pathways. These findings may provide rationale to combine MP with CTSS blockade for the effective treatment of OSCC.

Six-SOMAmer Index Relating to Immune, Protease and Angiogenic Functions Predicts Progression in IPF

RATIONALE

Biomarkers in easily accessible compartments like peripheral blood that can predict disease progression in idiopathic pulmonary fibrosis (IPF) would be clinically useful regarding clinical trial participation or treatment decisions for patients. In this study, we used unbiased proteomics to identify relevant disease progression biomarkers in IPF.

METHODS

Plasma from IPF patients was measured using an 1129 analyte slow off-rate modified aptamer (SOMAmer) array, and patient outcomes were followed over the next 80 weeks. Receiver operating characteristic (ROC) curves evaluated sensitivity and specificity for levels of each biomarker and estimated area under the curve (AUC) when prognostic biomarker thresholds were used to predict disease progression. Both logistic and Cox regression models advised biomarker selection for a composite disease progression index; index biomarkers were weighted via expected progression-free days lost during follow-up with a biomarker on the unfavorable side of the threshold.

RESULTS

A six-analyte index, scaled 0 to 11, composed of markers of immune function, proteolysis and angiogenesis [high levels of ficolin-2 (FCN2), cathepsin-S (Cath-S), legumain (LGMN) and soluble vascular endothelial growth factor receptor 2 (VEGFsR2), but low levels of inducible T cell costimulator (ICOS) or trypsin 3 (TRY3)] predicted better progression-free survival in IPF with a ROC AUC of 0.91. An index score ≥ 3 (group ≥ 2) was strongly associated with IPF progression after adjustment for age, gender, smoking status, immunomodulation, forced vital capacity % predicted and diffusing capacity for carbon monoxide % predicted (HR 16.8, 95% CI 2.2-126.7, P = 0.006).

CONCLUSION

This index, derived from the largest proteomic analysis of IPF plasma samples to date, could be useful for clinical decision making in IPF, and the identified analytes suggest biological processes that may promote disease progression.

Cysteine cathepsin proteases: regulators of cancer progression and therapeutic response

Cysteine cathepsin protease activity is frequently dysregulated in the context of neoplastic transformation. Increased activity and aberrant localization of proteases within the tumour microenvironment have a potent role in driving cancer progression, proliferation, invasion and metastasis. Recent studies have also uncovered functions for cathepsins in the suppression of the response to therapeutic intervention in various malignancies. However, cathepsins can be either tumour promoting or tumour suppressive depending on the context, which emphasizes the importance of rigorous in vivo analyses to ascertain function. Here, we review the basic research and clinical findings that underlie the roles of cathepsins in cancer, and provide a roadmap for the rational integration of cathepsin-targeting agents into clinical treatment.

Exploring the Molecular Mechanism and Biomakers of Liver Cancer Based on Gene Expression Microarray

Liver cancer is one of the most common cancers worldwide with high morbidity and mortality. Its molecular mechanism hasn’t been fully understood though many studies have been conducted and thus further researches are still needed to improve the prognosis of liver cancer. Firstly, differentially expressed genes (DEGs) between six Mdr2-knockout (Mdr2-KO) mutant mice samples (3-month-old and 12-month-old) and six control mice samples were identified. Then, the enriched GO terms and KEGG pathways of those DEGs were obtained using the Database for Annotation, Visualization and Integrated Discovery (DAVID, http://david.abcc.ncifcrf.gov/). Finally, protein-protein interactions (PPI) network of those DEGs were constructed using STRING database (http://www.string-db.org/) and visualized by Cytoscape software, at the same time, genes with high degree were selected out. Several novel biomarkers that might play important roles in liver cancer were identified through the analysis of gene microarray in GEO. Also, some genes such as Tyrobp, Ctss and pathways such as Pathways in cancer, ECM-receptor interaction that had been researched previously were further confirmed in this study. Through the bioinformatics analysis of the gene microarray in GEO, we found some novel biomarkers of liver cancer and further confirmed some known biomarkers.

miR-31 dysregulation in cystic fibrosis airways contributes to increased pulmonary cathepsin S production

RATIONALE

Cathepsin S (CTSS) activity is increased in bronchoalveolar lavage (BAL) fluid from patients with cystic fibrosis (CF). This activity contributes to lung inflammation via degradation of antimicrobial proteins, such as lactoferrin and members of the β-defensin family.

OBJECTIVES

In this study, we investigated the hypothesis that airway epithelial cells are a source of CTSS, and mechanisms underlying CTSS expression in the CF lung.

METHODS

Protease activity was determined using fluorogenic activity assays. Protein and mRNA expression were analyzed by ELISA, Western blotting, and reverse-transcriptase polymerase chain reaction.

MEASUREMENTS AND MAIN RESULTS

In contrast to neutrophil elastase, CTSS activity was detectable in 100% of CF BAL fluid samples from patients without Pseudomonas aeruginosa infection. In this study, we identified epithelial cells as a source of pulmonary CTSS activity with the demonstration that CF airway epithelial cells express and secrete significantly more CTSS than non-CF control cells in the absence of proinflammatory stimulation. Furthermore, levels of the transcription factor IRF-1 correlated with increased levels of its target gene CTSS. We discovered that miR-31, which is decreased in the CF airways, regulates IRF-1 in CF epithelial cells. Treating CF bronchial epithelial cells with a miR-31 mimic decreased IRF-1 protein levels with concomitant knockdown of CTSS expression and secretion.

CONCLUSIONS

The miR-31/IRF-1/CTSS pathway may play a functional role in the pathogenesis of CF lung disease and may open up new avenues for exploration in the search for an effective therapeutic target.

Inhibition of cathepsin S induces autophagy and apoptosis in human glioblastoma cell lines through ROS-mediated PI3K/AKT/mTOR/p70S6K and JNK signaling pathways

Cathepsin S is a lysosomal cysteine protease that is overexpressed in various cancer models and plays important role in tumorigenesis, however the mechanisms are unclear. In the present study, we found that inhibition of cathepsin S induced autophagy and mitochondrial apoptosis in human glioblastoma cells. Blockade of autophagy by either a chemical inhibitor or RNA interference attenuated cathespin S inhibition-induced apoptosis. Furthermore, autophagy and apoptosis induction was dependent on the suppression of phosphatidylinositide 3-kinases/protein kinase B/mammalian target of rapamycin/p70S6 kinase (PI3K/AKT/mTOR/p70S6K) signaling pathway and activation of c-Jun N-terminal kinase (JNK) signaling pathway. In addition, reactive oxygen species (ROS) served as an upstream of PI3K/AKT/mTOR/p70S6K and JNK signaling pathways. In conclusion, the current study revealed that cathepsin S played an important role in the regulation of autophagy and apoptosis in human glioblastoma cells.

Cysteine cathepsins and their potential in clinical therapy and biomarker discovery

Since their discovery, cysteine cathepsins were generally considered to be involved mainly in the nonspecific bulk protein degradation that takes place within the lysosomes. However, it has become clear that their proteolytical activity can also influence various specific pathological processes such as cancer, arthritis, and atherosclerosis. Furthermore, their localization was found not to be limited strictly to the lysosomes. In the light of those findings, it is not surprising that cysteine cathepsins are currently considered as highly relevant clinical targets. Moreover, recent development of proteomic-based methods for identification of novel physiological substrates of proteases provides a major opportunity also in the field of cysteine cathepsins. In this review, we will therefore present cysteine cathepsin roles in disease progression and discuss their potential relevance as prognostic and diagnostic biomarkers.

Cathepsin S-mediated autophagic flux in tumor-associated macrophages accelerate tumor development by promoting M2 polarization

BACKGROUND

Tumor-associated macrophages (TAMs) are the major component of tumor-infiltrating leukocytes. TAMs are heterogeneous, with distinct phenotypes influenced by the microenvironment surrounding tumor tissues, but relatively little is known about the key molecular in these cells that contribute to malignant phenotypes. Autophagic activity is a critical factor in tumor development that contributes to enhancing cellular fitness and survival in the hostile tumor microenvironment. However, the molecular basis and relations between autophagy and TAMs polarization remain unclear.

METHODS

Cathepsin S (Cat S) expression was analyzed in human colon carcinoma and normal colon tissues. In vivo effects were evaluated using PancO2 subcutaneous tumor model and SL4 hepatic metastasis model. Immunofluorescence staining, flow cytometry and real-time PCR were done to examine TAMs polarization. Western blotting assay, transmission electron microscopy, mCherry-GFP-LC3 transfection and DQ-BSA degradation assays were carried out to determine its role in regulating autophagy.

RESULTS

In the present study, we showed that the enhanced expression of Cat S correlated with the severity of histologic grade as well as clinical stage, metastasis, and recurrence, which are known indicators of a relatively poor prognosis of human colon carcinoma. Cat S knockout led to decreased tumor growth and metastasis. Moreover, Cat S knockout inhibited M2 macrophage polarization during tumor development. We further demonstrated that Cat S was required for not only autophagic flux but also the fusion processes of autophagosomes and lysosomes in TAMs. Importantly, we found that Cat S contributed to tumor development by regulating the M2 phenotype of TAMs through the activation of autophagy.

CONCLUSIONS

These results indicated that Cat S-mediated autophagic flux is an important mechanism for inducing M2-type polarization of TAMs, which leads to tumor development. These data provide strong evidence for a tumor-promoting role of autophagy in TAMs and suggest Cat S could be a potential target for cancer therapy.

Synthesis and radiopharmacological characterisation of a fluorine-18-labelled azadipeptide nitrile as a potential PET tracer for in vivo imaging of cysteine cathepsins

A fluorinated cathepsin inhibitor based on the azadipeptide nitrile chemotype was prepared and selected for positron emission tomography (PET) tracer development owing to its high affinity for the oncologically relevant cathepsins L, S, K and B. Labelling with fluorine-18 was accomplished in an efficient and reliable two-step, one-pot radiosynthesis by using 2-[(18) F]fluoroethylnosylate as a prosthetic agent. The pharmacokinetic properties of the resulting radiotracer compound were studied in vitro, ex vivo and in vivo in normal rats by radiometabolite analysis and small-animal positron emission tomography. These investigations revealed rapid conjugate formation of the tracer with glutathione in the blood, which is associated with slow blood clearance. The potential of the developed (18) F-labelled probe to image tumour-associated cathepsin activity was investigated by dynamic small-animal PET imaging in nude mice bearing tumours derived from the human NCI-H292 lung carcinoma cell line. Computational analysis of the obtained image data indicated the time-dependent accumulation of the radiotracer in the tumours. The expression of the target enzymes in the tumours was confirmed by immunohistochemistry with specific antibodies. This indicates that azadipeptide nitriles have the potential to target thiol-dependent cathepsins in vivo despite their disadvantageous pharmacokinetics.

Cathepsin S from both tumor and tumor-associated cells promote cancer growth and neovascularization

Recent murine studies have demonstrated that tumor-associated macrophages in the tumor microenvironment are a key source of the pro-tumorigenic cysteine protease, cathepsin S. We now show in a syngeneic colorectal carcinoma murine model that both tumor and tumor-associated cells contribute cathepsin S to promote neovascularization and tumor growth. Cathepsin S depleted and control colorectal MC38 tumor cell lines were propagated in both wild type C57Bl/6 and cathepsin S null mice to provide stratified depletion of the protease from either the tumor, tumor-associated host cells, or both. Parallel analysis of these conditions showed that deletion of cathepsin S inhibited tumor growth and development, and revealed a clear contribution of both tumor and tumor-associated cell derived cathepsin S. The most significant impact on tumor development was obtained when the protease was depleted from both sources. Further characterization revealed that the loss of cathepsin S led to impaired tumor vascularization, which was complemented by a reduction in proliferation and increased apoptosis, consistent with reduced tumor growth. Analysis of cell types showed that in addition to the tumor cells, tumor-associated macrophages and endothelial cells can produce cathepsin S within the microenvironment. Taken together, these findings clearly highlight a manner by which tumor-associated cells can positively contribute to developing tumors and highlight cathepsin S as a therapeutic target in cancer.

Proteomics reveals acute pro-inflammatory and protective responses in rat Kupffer cells and hepatocytes after chemical initiation of liver cancer and after LPS and IL-6

Inflammation is a key event in the development of liver cancer. We studied early inflammatory responses of Kupffer cells (KCs) and hepatocyte (HC) after cancer initiation. The chemical carcinogen N-nitrosomorpholine (NNM) was used in a rat model. We applied a comprehensive analytical strategy including metabolic labeling, 2-D PAGE, LC-MS/MS-based spot identification and shotgun proteomics and thus determined the rates of synthesis of individual proteins, compared whole tissue with isolated constituent cells and performed in vivo to in vitro comparisons of NNM effects. NNM increased synthesis of overall and 138 individual proteins identified in HC and/or KC, indicating reprogramming of metabolism favoring protection, repair and replacement of cell constituents in HC and KC. Secretome analysis by 2-D PAGE and shotgun proteomics of HC revealed the induction of acute phase proteins, in case of KC of proteases, cytokines and chemokines, indicating inflammatory effects. All responses were induced rapidly, independently of signals from other cells, and closely mimicked the pro-inflammatory and protective effects of inflammation modulators LPS in KC and IL-6 in HC. In conclusion, the carcinogen NNM exerts pro-inflammatory effects in the liver, partially by direct activation of KC. The acute inflammation and its protective component will enhance formation, survival and proliferation of initiated cells and may therefore act synergistically with the genotoxic action of the carcinogen.

Silencing cathepsin S gene expression inhibits growth, invasion and angiogenesis of human hepatocellular carcinoma in vitro

Cathepsin S (Cat S) plays an important role in tumor invasion and metastasis by its ability to degrade extracellular matrix (ECM). Our previous study suggested there could be a potential association between Cat S and hepatocellular carcinoma (HCC) metastasis. The present study was designed to determine the role of Cat S in HCC cell growth, invasion and angiogenesis, using RNA interference technology. Small interfering RNA (siRNA) sequences for the Cat S gene were synthesized and transfected into human HCC cell line MHCC97-H. The Cat S gene targeted siRNA-mediated knockdown of Cat S expression, leading to potent suppression of MHCC97-H cell proliferation, invasion and angiogenesis. These data suggest that Cat S might be a potential target for HCC therapy.

Inhibition of Cathepsin S by Fsn0503 enhances the efficacy of chemotherapy in colorectal carcinomas

Cathepsin S is a lysosomal cysteine protease implicated in tumourigenesis with key roles in invasion and angiogenesis. We have previously shown that the specific inhibition of Cathepsin S using a monoclonal antibody (Fsn0503) blocks colorectal carcinoma tumour growth and angiogenesis in vivo. We investigated whether Cathepsin S expression levels were affected by chemotherapy in human cancer cell lines by RT-PCR. Using colorectal xenograft models, we examined the therapeutic benefit of Cathepsin S inhibition using Fsn0503 in combination with a metronomic dosing regimen of CPT-11. We analysed the effects of the combination therapy on tumour progression and on tumour vascularisation by immunohistochemical staining of tumours. Cathepsin S expression levels are upregulated in HCT116, LoVo, Colo205 cell lines and HUVECs after exposure to CPT-11 in vitro. The administration of Fsn0503 in combination with CPT-11 significantly attenuated tumour growth in comparison to CPT-11 alone in colorectal HCT116 xenograft models. Furthermore, analysis of tumour vascularisation revealed that this was also significantly disrupted by the combination treatment. These results show that the combination of Cathepsin S inhibition with CPT-11 enhances the therapeutic effect of the chemotherapy. This rationale may have clinical application in the treatment of colorectal cancer upon further evaluation.

Molecular Imaging of Proteases in Cancer

Proteases play important roles during tumor angiogenesis, invasion, and metastasis. Various molecular imaging techniques have been employed for protease imaging: optical (both fluorescence and bioluminescence), magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), and positron emission tomography (PET). In this review, we will summarize the current status of imaging proteases in cancer with these techniques. Optical imaging of proteases, in particular with fluorescence, is the most intensively validated and many of the imaging probes are already commercially available. It is generally agreed that the use of activatable probes is the most accurate and appropriate means for measuring protease activity. Molecular imaging of proteases with other techniques (i.e. MRI, SPECT, and PET) has not been well-documented in the literature which certainly deserves much future effort. Optical imaging and molecular MRI of protease activity has very limited potential for clinical investigation. PET/SPECT imaging is suitable for clinical investigation; however the optimal probes for PET/SPECT imaging of proteases in cancer have yet to be developed. Successful development of protease imaging probes with optimal in vivo stability, tumor targeting efficacy, and desirable pharmacokinetics for clinical translation will eventually improve cancer patient management. Not limited to cancer, these protease-targeted imaging probes will also have broad applications in other diseases such as arthritis, atherosclerosis, and myocardial infarction.

Relationship between expression of Cathepsin S and digestive system neoplasms

Cathepsin, a kind of cysteine proteinases, is found in the 1920 and able to degrade extracellular matrix (ECM) components. Cathepsin S is a single-chain and non-glycosylated cysteine proteinase ubiquitously distributed in lysosomes. Apart from its role in human digestive system neoplasms, Cathepsin S was also identified to participate in the occurrence of astrocytoma, glioblastoma, prostatic carcinoma and lung cancer. It is found that cathepsin S is directly involved in vascular matrix remodeling. In addition, the expression of cathepsin S is associated with the angiogenesis, growth and metastasis of tumors. This article reviews the relationship between cathepsin S expression and digestive system neoplasms.

Vesicle-associated protein 1: a novel ovarian immunocontraceptive target in the common brushtail possum, Trichosurus vulpecula

Ovarian-based immunological research is currently restricted to proteins of the zona pellucida. This study examined the immunocontraceptive potential of a novel vesicle-associated protein, VAP1, previously isolated from the vesicle-rich hemisphere of the brushtail possum oocyte. Seven female possums were immunized against recombinant glutathione S-transferase-VAP1 fusion protein. Control animals (n=3) received antigen-free vaccinations. Following immunization, regular blood sampling determined the level and duration of immune response. Animals were monitored daily, pre- and post-immunization, to determine estrous cycling activity and the percentage of reproductive cycles yielding viable young. The reproductive tracts and somatic organs of VAP1-immunized (n=7), control-immunized (n=3) and non-immunized (n=5) animals were collected and examined by histology and transmission electron microscopy. VAP1 immunization caused a strong and sustained immune response. Elevated levels of VAP1 antibody binding were detected in sera following initial injections, and immune titers rose as boosters were administered. Immunization had no adverse effect upon animal behavior or body condition. Immunized females demonstrated no major change in annual estrous cycling activity; however, the percentage of reproductive cycles resulting in pouch young decreased significantly (P<0.05) by 40%. Histological and ultrastructural analyses revealed an abundance of lipid-like degradation bodies within the ooplasm of developing oocytes and the cytoplasm of failing uterine zygotes. Active macrophage invasion of enlarged endometrial glands was observed in the uteri of two females. Reproductive tract changes are discussed in relation to observed fertility decline. The results of this study indicate that VAP1 has exciting potential as an immunocontraceptive target for possum control in New Zealand.

Detection of cathepsin S cysteine protease in human brain tumour microdialysates in vivo

Microdialysis enables the chemistry of extracellular fluid in body tissues to be measured. Extracellular proteases such as the cysteine protease, cathepsin S (CatS), are thought to facilitate astrocytoma invasion. Microdialysates obtained from human brain tumours in vivo were subjected to cathepsin S activity and ELISA assays. Cathepsin S ELISA expression was detected in five out of 10 tumour microdialysates, while activity was detected in five out of 11 tumour microdialysates. Cathepsin S expression was also detected in microdialysate from the normal brain control although no activity was found in the same sample. While some refinements to the technique are necessary, the authors demonstrate the feasibility and safety of microdialysis in human astrocytomas in vivo. Characterisation of the extracellular environment of brain tumours in vivo using microdialysis may be a useful tool to identify the protease profile of brain tumours.