New functional aspects of cathepsin D and cathepsin E

Novel insights into the nervous system affected by prolonged hyperglycemia

Multiple molecular pathways including the receptor for advanced glycation end-products-diaphanous related formin 1 (RAGE-Diaph1) signaling are known to play a role in diabetic peripheral neuropathy (DPN). Evidence suggests that neuropathological alterations in type 1 diabetic spinal cord may occur at the same time as or following peripheral nerve abnormalities. We demonstrated that DPN was associated with perturbations of RAGE-Diaph1 signaling pathway in peripheral nerve accompanied by widespread spinal cord molecular changes. More than 500 differentially expressed genes (DEGs) belonging to multiple functional pathways were identified in diabetic spinal cord and of those the most enriched was RAGE-Diaph1 related PI3K-Akt pathway. Only seven of spinal cord DEGs overlapped with DEGs from type 1 diabetic sciatic nerve and only a single gene cathepsin E (CTSE) was common for both type 1 and type 2 diabetic mice. In silico analysis suggests that molecular changes in spinal cord may act synergistically with RAGE-Diaph1 signaling axis in the peripheral nerve. KEY MESSAGES: Molecular perturbations in spinal cord may be involved in the progression of diabetic peripheral neuropathy. Diabetic peripheral neuropathy was associated with perturbations of RAGE-Diaph1 signaling pathway in peripheral nerve accompanied by widespread spinal cord molecular changes. In silico analysis revealed that PI3K-Akt signaling axis related to RAGE-Diaph1 was the most enriched biological pathway in diabetic spinal cord. Cathepsin E may be the target molecular hub for intervention against diabetic peripheral neuropathy.

An Optimally Fabricated Platform Guides Cancer-Specific Activation of Chemotherapeutic Drugs and Toxicity-free Cancer Treatment

Cancer chemotherapeutic drugs such as doxorubicin, mitomycin C, and gemcitabine, which are mostly small synthetic molecules, are still clinically useful for cancer treatment. However, despite considerable therapeutic efficacy, severe toxicity-associated problems, which are mainly caused by the non-specific mode of action such as chromosomal DNA damage and interference in the DNA replication even in normal cells, remain unresolved and a major challenge for safer and thus more widespread adoption of chemotherapy. Here we developed an innovative platform through beneficially integrating core peptide units into highly-ordered, stable, and flexibly guest-adaptable structure of apoferritin, which simultaneously fulfills high-capacity loading of chemotherapeutic drugs compared  with the case of FDA-approved antibody-drug conjugates, efficient drug targeting to cancer cells, and cancer cell-specific drug release and activation. This approach dramatically reduced drug toxicity to normal cells, significantly enhanced efficacy in in vivo cancer treatment without toxicity to normal organs of mice, and thus is expected to open up a novel clinical route to break through the limits of current cancer chemotherapy. This article is protected by copyright. All rights reserved.

Cathepsin D interacts with adenosine A2A receptors in mouse macrophages to modulate cell surface localization and inflammatory signaling

Adenosine A_2A receptor (A_2AR)–dependent signaling in macrophages plays a key role in the regulation of inflammation. However, the processes regulating A_2AR targeting to the cell surface and degradation in macrophages are incompletely understood. For example, the C-terminal domain of the A_2AR and proteins interacting with it are known to regulate receptor recycling, although it is unclear what role potential A_2AR-interacting partners have in macrophages. Here, we aimed to identify A_2AR-interacting partners in macrophages that may effect receptor trafficking and activity. To this end, we performed a yeast two-hybrid screen using the C-terminal tail of A_2AR as the “bait” and a macrophage expression library as the “prey.” We found that the lysosomal protease cathepsin D (CtsD) was a robust hit. The A_2AR–CtsD interaction was validated in vitro and in cellular models, including RAW 264.7 and mouse peritoneal macrophage (IPMΦ) cells. We also demonstrated that the A_2AR is a substrate of CtsD and that the blockade of CtsD activity increases the density and cell surface targeting of A_2AR in macrophages. Conversely, we demonstrate that A_2AR activation prompts the maturation and enzymatic activity of CtsD in macrophages. In summary, we conclude that CtsD is a novel A_2AR-interacting partner and thus describe molecular and functional interplay that may be crucial for adenosine-mediated macrophage regulation in inflammatory processes.

Redox State and Lysosomal Activity in Women with Ovarian Cancer with Tumor Recurrence and Multiorgan Metastasis

The aim of the study is to evaluate oxidant-antioxidant balance as well as lysosomal and anti-protease activities in ovarian cancer since it has been emphasized that the crucial inducing factor of carcinogenesis may be reactive oxygen/nitrogen species or, more precisely, oxidative stress-induced inflammation. The study involved 15 women with ovarian cancer, aged 59.9 ± 7.8 years, and 9 healthy women aged 56.3 ± 4.3 years (controls). The study material was venous blood collected from fasting subjects. In erythrocytes, the activities of superoxide dismutase, glutathione peroxidase, and catalase, as well as concentrations of conjugated dienes (CDs) and thiobarbituric acid reactive substances (TBARS), were investigated. CD, TBARS, and vitamins A and E plasma concentrations were also determined. Moreover, total antioxidant capacity and concentrations of 4-hydroxynonenal adducts and 8-iso-prostaglandin F2α, as well as activities of acid phosphatase, arylsulfatase, cathepsin D, and α₁-antitrypsin, were studied in serum. The vitamin E and 8-iso-prostaglandin F2α concentrations as well as arylsulfatase activity were lower in the women with cancer compared to the controls (p = 0.006, p = 0.03, p = 0.001, respectively). In contrast, cathepsin D activity was lower in the controls (p = 0.04). In the peripheral blood of the women with cancer, oxidant-antioxidant and lysosomal disturbances were observed.

The Impact of Modern Therapeutic Methods on the Oxidant-Antioxidant Equilibrium and Activities of Selected Lysosomal Enzymes and Serine Protease Inhibitor in Amateur Athletes

Deep electromagnetic stimulation (DEMS) and low-frequency ultrasound (US) are new physical therapy methods used in the rehabilitation of the musculoskeletal system and wound healing. They are applied locally to treat the injured tissues. The beneficial effects of these methods in supportive care have been documented, but accurate biochemical effects are not known. The goal was to assess the effect of single DEMS and US sessions on the oxidant-antioxidant equilibrium, as well as the activities of lysosomal hydrolases and α ₁-antitrypsin (AAT) in peripheral blood of juvenile injured amateur athletes. In the athletes with low back pain (DEMS treated, N = 16) and pain in the shoulder or ankle joint (US treated, N = 14), as well as in healthy control amateur athletes (DEMS treated, N = 14; US treated, N = 17), before the sessions and 30 minutes and 24 hours after them, the levels of the following parameters were determined: thiobarbituric acid reactive substances (TBARS) in erythrocytes and plasma, superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) in erythrocytes, as well as acid phosphatase (AcP), arylsulfatase (ASA), cathepsin D (CTS D), and α ₁-antitrypsin (AAT) in serum. After both procedures, the levels of parameters changed in a negligible manner, excluding the cathepsin D activity, which was statistically significantly lower 30 min and 24 h after US in the control athletes compared to the baseline activity determined directly before the procedure (47.5% and 55.7% differences, respectively). Similar tendency was observed after DEMS (p > 0.05). The procedures, especially low-frequency US, decrease lysosomal proteolytic activity and do not significantly disrupt the oxidant-antioxidant and lysosomal equilibriums in the peripheral blood both of healthy and injured athletes. No systemic acute-phase response of AAT was also detected in the athletes after both procedures. This trial is registered with CTRI/2018/01/011344.

The impact of high-intensity laser therapy on oxidative stress, lysosomal enzymes, and protease inhibitor in athletes

The aim of the study was to assess the effect of one session of high-intensity laser therapy (HILT) on the levels of selected oxidative stress parameters, lysosomal hydrolases, and anti-inflammatory serine protease inhibitor in the peripheral blood of amateur athletes with torn or pulled tendons of the ankle or the knee joint. The group of injured athletes comprised 16 males and females aged 16.3 ± 1.3 years, while the control group of 14 healthy, noninjured amateur athletes of both sexes (controls; age 17.4 ± 4.6 years). Material for the study was peripheral blood taken at three study time points: Immediately before, 30 min after, and 24 h after HILT intervention. In plasma and erythrocytes, thiobarbituric acid reactive substances (TBARSpl and TBARSer, respectively) were determined. In erythrocytes, the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) were measured. In serum, the activity of acid phosphatase (AcP), arylsulfatase (ASA), cathepsin D (CTS D), and α1-antitrypsin (AAT) were determined. Among oxidative stress parameters, only the CAT activity significantly decreased 24 h after HILT compared to measurement 30 min after the treatment in the injured individuals (P < 0.01), while the GPx activity in that group was meaningfully higher 30 min after HILT compared to controls (P < 0.05). Thirty min after the intervention, the activities of AcP and ASA were lower in the injured participants compared to the uninjured ones (P < 0.01 and P < 0.05, respectively). The CTS D activity was lower 30 min and 24 h after HILT in both groups (P < 0.001) and did not differ significantly between them (P > 0.05). Moreover, the study showed statistically significant linear relationships between the TBARSer concentration and the SOD activity before HILT in the healthy participants (r = -0.6, P = 0.021) and 24 h after HILT in the injured ones (r = 0.6, P = 0.025). In the noninjured athletes before HILT, the CTS D activity linearly correlated with the AAT activity (r = -0.70, P = 0.005), and 30 min after the treatment, with the AcP activity (r = 0.5, P = 0.041). 24 h after the HILT intervention, the CTS D and AcP activities were also correlated in the injured athletes (r = 0.8, P = 0.002). The study suggests that one HILT intervention does not significantly influence the redox equilibrium but stabilizes lysosomal membranes.

Proteomic responses to elevated ocean temperature in ovaries of the ascidian Ciona intestinalis

Ciona intestinalis, a common sea squirt, exhibits lower reproductive success at the upper extreme of the water temperatures it experiences in coastal New England. In order to understand the changes in protein expression associated with elevated temperatures, and possible response to global temperature change, we reared C. intestinalis from embryos to adults at 18°C (a temperature at which they reproduce normally at our collection site in Rhode Island) and 22°C (the upper end of the local temperature range). We then dissected ovaries from animals at each temperature, extracted protein, and measured proteomic levels using shotgun mass spectrometry (LC-MS/MS). 1532 proteins were detected at a 1% false discovery rate present in both temperature groups by our LC-MS/MS method. 62 of those proteins are considered up- or down-regulated according to our statistical criteria. Principal component analysis shows a clear distinction in protein expression pattern between the control (18°C) group and high temperature (22°C) group. Similar to previous studies, cytoskeletal and chaperone proteins are upregulated in the high temperature group. Unexpectedly, we find evidence that proteolysis is downregulated at the higher temperature. We propose a working model for the high temperature response in C. intestinalis ovaries whereby increased temperature induces upregulation of signal transduction pathways involving PTPN11 and CrkL, and activating coordinated changes in the proteome especially in large lipid transport proteins, cellular stress responses, cytoskeleton, and downregulation of energy metabolism.

AT1-receptor blockade attenuates outward aortic remodeling associated with diet-induced obesity in mice

The renin-angiotensin system (RAS) and obesity have been implicated in vascular outward remodeling, including aneurysms, but the precise mechanisms are not yet understood. We investigated the effect of the angiotensin receptor type 1 (AT1-receptor) antagonist telmisartan on aortic outward remodeling in a diet-induced obesity model in mice. C57/Black6J mice were fed either a low-fat diet (LFD) or a high-fat diet (HFD) for 14 weeks. One group of HFD mice was additionally exposed to telmisartan (3 mg/kg per day) for the last 4 weeks. HFD led to aortic outward remodeling, characterized by increased proteolysis, along with structural changes, such as fragmentation of elastic fibers and decreased elastin content. Vascular damage was associated with up-regulation of matrix metalloproteinase (MMP)-2 (MMP-2), MMP-3, MMP-12, cathepsin D, and cathepsin B. HFD aortae exhibited an enhanced inflammatory status, characterized by tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β) colocalized with adipocytes in the adventitia. HFD resulted in a significant increase in aortic dimensions, evident by ultrasound measurements. Telmisartan abolished aortic dilatation and preserved elastin content. HFD induced enhanced expression of aortic MMP-2, MMP-9, and TNF-α was abrogated by telmisartan. Adventitial proteolytic and inflammatory factors were also examined in samples from human abdominal aneurysms. The expression of TNF-α, IL-1β, and MMP-9 was higher in the adventitial fat of diseased vessels compared with healthy tissues. Finally, adipocytes treated with TNF-α showed enhanced MMP-2, MMP-3, and cathepsin D, which was prevented by telmisartan. Taken together, HFD in mice induced aortic dilatation with up-regulation of matrix degrading and inflammatory pathways similar to those seen in human aortic aneurysmatic tissue. The HFD-induced vascular pathology was reduced by AT1-receptor antagonist telmisartan.

Optical imaging probes in oncology

Cancer is a complex disease, characterized by alteration of different physiological molecular processes and cellular features. Keeping this in mind, the possibility of early identification and detection of specific tumor biomarkers by non-invasive approaches could improve early diagnosis and patient management.Different molecular imaging procedures provide powerful tools for detection and non-invasive characterization of oncological lesions. Clinical studies are mainly based on the use of computed tomography, nuclear-based imaging techniques and magnetic resonance imaging. Preclinical imaging in small animal models entails the use of dedicated instruments, and beyond the already cited imaging techniques, it includes also optical imaging studies. Optical imaging strategies are based on the use of luminescent or fluorescent reporter genes or injectable fluorescent or luminescent probes that provide the possibility to study tumor features even by means of fluorescence and luminescence imaging. Currently, most of these probes are used only in animal models, but the possibility of applying some of them also in the clinics is under evaluation.The importance of tumor imaging, the ease of use of optical imaging instruments, the commercial availability of a wide range of probes as well as the continuous description of newly developed probes, demonstrate the significance of these applications. The aim of this review is providing a complete description of the possible optical imaging procedures available for the non-invasive assessment of tumor features in oncological murine models. In particular, the characteristics of both commercially available and newly developed probes will be outlined and discussed.

Expression profile of cathepsins indicates the potential of cathepsins B and D as prognostic factors in breast cancer patients

Breast cancer is one of the most prevalent types of cancer in women and contributes to 32% of all female cancer cases. Cathepsins, a family of proteins, are known to have a critical role in human cancers. However, previous studies on the systematic analysis of the role of cathepsin family members in breast cancer are limited. The aim of the present study was to identify biological markers to predict prognosis and treatment response of breast cancer patients, as well as to elucidate novel therapeutic targets. The present study analyzed the expression of six members of cathepsin family, including cathepsins B, G, D, K, L and V in 188 breast cancer tissue specimens using immunohistochemistry. The data showed that all members of the tested cathepsin families featured cytoplasmic staining. Notably, expression of cathepsin L was associated with advanced tumor stages, while cathepsins B and K expression levels were associated with positive estrogen receptor expression; in addition, cathepsin K expression was also demonstrated to be associated with progesterone receptor expression. Cathepsins V and D expression levels were found to be associated with breast cancer metastasis, while the expression levels of cathepsins B and D were associated with poor disease-free survival in breast cancer patients. In addition, univariate analysis demonstrated that breast cancer metastasis to the bone and the expression of cathepsin B protein were associated with poor disease-free survival. In conclusion, the results of the present study indicated that the altered expression of cathepsins, in particular cathepsins B and D, contributed to the progression of breast cancer and poor disease-free survival in breast cancer patients.

Cathepsin D acts as an essential mediator to promote malignancy of benign prostatic epithelium

BACKGROUND

Stromal-epithelial interactions are important in both development and prostate cancer. Stromal changes have been shown to be powerful prognostic indicators of prostate cancer progression and of patient death helping to define lethal versus indolent phenotypes. The specific molecular underpinnings of these interactions are incompletely understood. We investigated whether stromal cathepsin D (CathD) overexpression affects prostate tumorigenesis through a paracrine mechanism.

METHODS

Normal prostate fibroblasts (NPF) were retrovirally transduced to overexpress cyclin D1 (CD1) and were designated NPF(CD1) . Cathepsin D expression was knocked down using shRNA in cancer associated fibroblasts (CAF) and NPF(CD1) . We analyzed these stromal cell lines using immunohistochemistry, Western blot, and tissue recombination.

RESULTS

An examination of human prostate tissue revealed significantly increased stromal staining of CathD in malignant prostate tissue. Overexpression of CD1 in normal prostate fibroblasts (NPF(CD1) ) produced a phenotype similar to, but more moderate than, CAF in a tissue recombination model. Knockdown studies revealed that CathD is required for NPF(CD1) motility and invasive growth in vitro. BPH-1 cell proliferation was found to be induced when cultured with NPF(CD1) conditioned medium, this effect was inhibited when CathD was knocked down in NPF(CD1) cells. Overexpression of CathD in prostate stromal cells induced malignancy in adjacent epithelium, and this transformation was inhibited when stromal CathD expression was knocked down in CAF.

CONCLUSIONS

The study presented here demonstrates increased CathD expression is seen in human CAF. The upregulation of CD1 results in concomitant increases in CathD expression. Elevated CathD expression in the stroma contributes to tumor promotion.

Cathepsin E is a marker of gastric differentiation and signet-ring cell carcinoma of stomach: a novel suggestion on gastric tumorigenesis

Gastric cancer (GC) presents various histological features, though the mechanism underlying its diversity is seldom elucidated. It is mainly classified into well differentiated tubular adenocarcinoma (tub1), moderately differentiated tubular adenocarcinoma (tub2), poorly differentiated adenocarcinoma (por), signet-ring cell carcinoma (sig), mucinous adenocarcinoma (muc), and papillary adenocarcinoma (pap). By screening, we found cathepsin E (CTSE) expresses universally in sig-type, occasionally in por-type, and rarely in tub1/tub2-type GC cell lines. In surgically-resected specimens, CTSE was immunostained in 50/51 sig-type (98.0%), 3/10 tub1-type (30.0%), 7/18 tub2-type (38.9%), 15/26 por-type (57.7%), 4/10 pap-type (40.0%), and 0/3 muc-type (0.0%) GC. In endoscopically-resected specimens, 6/7 sig-type (85.7%), 7/52 tub1-type (13.7%), 5/12 tub2-type (41.7%), 2/7 pap-type (28.6%) GC and 0/6 adenoma (0.0%) expressed CTSE. For non-malignant tissues, CTSE is universally expressed in normal fundic, pyloric, and cardiac glands of stomach, but hardly in other digestive organs. In the precancerous intestinal metaplasia of stomach, CTSE is mostly observed in mixed gastric-and-intestinal type and deficient in solely-intestinal type. CTSE expression is positively correlated with gastric marker MUC5AC (p<0.0001) and negatively correlated with intestinal marker MUC2 (p = 0.0019). For sig-type GC, in both tumors and background mucosa, expression of MUC5AC and CTSE is high whereas that of MUC2 is low, indicating that sig-type GC reflects the features of background mucosa. For gastric adenoma and tub1/tub2-type GC, more undifferentiated tumors tend to show higher expression of CTSE with MUC5AC and lower expression of MUC2 in tumors, but they tend to present lower expression of CTSE, MUC5AC and MUC2 in background mucosa. These suggest that more malignant gastric adenocarcinoma with stronger gastric and weaker intestinal properties tend to arise from background mucosa with decreased both gastric and intestinal features. In conclusion, CTSE is a marker of both gastric differentiation and signet-ring cell carcinoma, which should shed light on the mechanism of gastric tumorigenesis.

Emerging roles of cathepsin E in host defense mechanisms

Cathepsin E is an intracellular aspartic proteinase of the pepsin superfamily, which is predominantly expressed in certain cell types, including the immune system cells and rapidly regenerating gastric mucosal and epidermal keratinocytes. The intracellular localization of this protein varies with different cell types. The endosomal localization is primarily found in antigen-presenting cells and gastric cells. The membrane association is observed with certain cell types such as erythrocytes, osteoclasts, gastric parietal cells and renal proximal tubule cells. This enzyme is also found in the endoplasmic reticulum, Golgi complex and cytosolic compartments in various cell types. In addition to its intracellular localization, cathepsin E occurs in the culture medium of activated phagocytes and cancer cells as the catalytically active enzyme. Its strategic expression and localization thus suggests the association of this enzyme with specific biological functions of the individual cell types. Recent genetic and pharmacological studies have particularly suggested that cathepsin E plays an important role in host defense against cancer cells and invading microorganisms. This review focuses emerging roles of cathepsin E in immune system cells and skin keratinocytes, and in host defense against cancer cells. This article is part of a Special Issue entitled: Proteolysis 50 years after the discovery of lysosome.

Proteomic profiling of the epileptic dentate gyrus

The development of epilepsy is often associated with marked changes in central nervous system cell structure and function. Along these lines, reactive gliosis and granule cell axonal sprouting within the dentate gyrus of the hippocampus are commonly observed in individuals with temporal lobe epilepsy (TLE). Here we used the pilocarpine model of TLE in mice to screen the proteome and phosphoproteome of the dentate gyrus to identify molecular events that are altered as part of the pathogenic process. Using a two-dimensional gel electrophoresis-based approach, followed by liquid chromatography-tandem mass spectrometry, 24 differentially expressed proteins, including 9 phosphoproteins, were identified. Functionally, these proteins were organized into several classes, including synaptic physiology, cell structure, cell stress, metabolism and energetics. The altered expression of three proteins involved in synaptic physiology, actin, profilin 1 and α-synuclein was validated by secondary methods. Interestingly, marked changes in protein expression were detected in the supragranular cell region, an area where robust mossy fibers sprouting occurs. Together, these data provide new molecular insights into the altered protein profile of the epileptogenic dentate gyrus and point to potential pathophysiologic mechanisms underlying epileptogenesis.

Mining of serum glycoproteins by an indirect approach using cell line secretome

Glycosylation is the most important and abundant post-translational modification in serum proteome. Several specific types of glycan epitopes have been shown to be associated with various types of disease. Direct analysis of serum glycoproteins is challenging due to its wide dynamic range. Alternatively, glycoproteins can be discovered in the secretome of model cell lines and then confirmed in blood. However, there has been little experimental evidence showing cell line secretome as a tractable target for the study of serum glycoproteins. We used a hydrazine-based glycocapture method to selectively enrich glycoproteins from the secretome of the breast cancer cell line Hs578T. A total of 132 glycoproteins were identified by nanoLC-MS/MS analysis. Among the identified proteins, we selected 13 proteins that had one or more N-glycosylation motifs in the matched peptides, which were included in the Secreted Protein Database but not yet in the Plasma Proteome Database (PPD), and whose antibodies were commercially available. Nine out of the 13 selected proteins were detected from human blood plasma by western analysis. Furthermore, eight proteins were also detected from the plasma by targeted LC-MS/MS, which had never been previously identified by data-dependent LC-MS/MS. Our results provide novel proteins that should be enrolled in PPD and suggest that analysis of cell line secretome with subfractionation is an efficient strategy for discovering disease-relevant serum proteins.

Stress transcriptomics in fish: a role for genomic cortisol signaling

The physiological responses to stressors, including hormonal profiles and associated tissue responsiveness have been extensively studied in teleosts, but the molecular mechanisms associated with this adaptive response are not well understood. The advent of cDNA microarray technology has transformed the field of functional genomics by revealing global gene expression changes in response to stressor exposures even in non-mammalian vertebrates, including fish. A unifying response in studies related to stressor exposure is activation of the hypothalamus-pituitary-interrenal (HPI) axis in fish, leading to cortisol release into the circulation. Here we will discuss the implications of some of the gene expression changes observed in response to acute stress in fish, while highlighting a role for cortisol in this adaptive stress response. As liver is a key organ for metabolic adjustments to stressors and also is a major target for cortisol action, the genomic studies pertaining to stress and glucocorticoid regulation have focused mainly on this tissue. The studies have identified several genes that are altered transiently after an acute stressor exposure in fish. A number of these stress-responsive genes were also modulated by glucocorticoid receptor activation, suggesting that elevation in cortisol levels during stressor exposure may be a key signal for target tissue molecular programming, essential for stress adaptation. The identification of regulatory gene networks that are stress activated, and modulated by cortisol, both in hepatic and extra-hepatic tissues, including gonads, brain, immune cells and gills, will provide a mechanistic framework to characterize the multifaceted role of cortisol during stress adaptation.

Activation of cell death pathways in the inner ear of the aging CBA/J mouse

We have previously demonstrated that oxidative stress increases in the inner ear of aging CBA/J mice and might contribute to the loss of function of the sensory system. We now investigate the activation of cell death pathways in the cochleae of these animals. Middle-aged (12 months) and old (18-26 months) mice with hearing deficits displayed outer hair cell nuclei with apoptotic and, to a lesser extent, necrotic features. Both intrinsic and extrinsic cell death pathways were activated by translocation or post-translational modification of proteins in the aging cochlea as compared to young (3 months) animals. Cytosolic cytochrome c increased, formed a complex with, and activated caspase 9. Endonuclease G translocated to the nuclei of aging outer hair cells suggesting its function as an apoptotic DNase. The cleaved (and hence active) forms of calpain I and calpain II increased while active cathepsin D was transiently elevated in middle-aged but not old animals. Finally, increases in the phosphorylation of p38 MAPK and JNK implicated the additional involvement of the MAPK pathway. The results suggest that multiple cell death pathways, all potentially linked to oxidative stress, are activated in hair cells of the auditory organ in aging mice.

Atlas of dihydrotestosterone actions on the transcriptome of prostate in vivo

BACKGROUND

Using serial analysis of gene expression (SAGE), we studied the transcriptomic changes in vivo by dihydrotestosterone (DHT) treatment in mice to better understand androgen effects in the prostate.

METHODS

Approximately 872,000 SAGE tags were isolated from intact and castrated (GDX) mice with and without DHT injection.

RESULTS

GDX significantly altered 431 transcripts, including 110 transcripts restored by DHT, and 146 potentially new transcripts. Totally, 187 transcripts were significantly affected by DHT treatment, of which 124 were induced and 63 were repressed. Interestingly and consistent with the prostate's secretory role, DHT up-regulated the expression of many genes involved in various steps of protein metabolism such as synthesis, folding, and secretion. GDX modulated the expression of genes which induce cell apoptosis and inhibit cell proliferation through polyamine biosynthesis, retinoid X receptor actions as well as several signaling pathways and some related factors. These results clarify DHT effects on prostate transcriptome in the areas of protein metabolism, cell proliferation and apoptosis. In addition, we detected gene expression changes in metabolic pathways, cytoskeleton, immunity and endoplasmic reticulum stress. Furthermore, knockdown of S-adenosylmethionine decarboxylase 1 in LNCaP cells confirmed the importance of androgen-regulated genes (ARGs) in prostate cancer cell growth.

CONCLUSION

Our data support the idea that ARGs are essential for the normal development of the prostate and can also be responsible for the pathogenesis of the prostate cancer.

Development of systemic in vitro evolution and its application to generation of peptide-aptamer-based inhibitors of cathepsin E

Proteases are involved in various biological functions. Thus, inhibition of their activities is scientifically interesting and medically important. However, there is no systematic method established to date to generate endopeptidase inhibitory peptides. Here, we report a general system to identify endopeptidase inhibitory peptides based on the use of in vitro evolution. Using this system, we generated peptides that inhibit cathepsin E (CE) specifically at a submicromolar IC(50). This system generates protease inhibitor peptides utilizing techniques of cDNA display, selection-by-function, Y-ligation-based block shuffling, and others. We further demonstrated the importance and effectiveness of a secondary library for obtaining small-sized and active peptides. CE inhibitory peptides generated by this method were characterized by a small size (8 to 12 aa) and quite different sequences, suggesting that they bind to different sites on CE. Typical CE inhibitory peptide aptamers obtained here (P(i)101; SCGG IIII SCIA) have half an inhibition activity (K(i); 5 nM) of pepstatin A (potent CE inhibitor) without inhibiting cathepsin D (structurally similar to CE). The general applicability of this system suggests that it may be useful to identify inhibitory peptides for various kinds of proteases and that it may therefore contribute to protein science and drug discovery. The peptide binding to a protein is discussed in comparison with the antibody binding to an antigen.

Insulin protects islets from apoptosis via Pdx1 and specific changes in the human islet proteome

Insulin is both a hormone regulating energy metabolism and a growth factor. We and others have shown that physiological doses of insulin initiate complex signals in primary human and mouse beta-cells, but the functional significance of insulin's effects on this cell type remains unclear. In the present study, the role of insulin in beta-cell apoptosis was examined. Exogenous insulin completely prevented apoptosis induced by serum withdrawal when given at picomolar or low nanomolar concentrations but not at higher concentrations, indicating that physiological concentrations of insulin are antiapoptotic and that insulin signaling is self-limiting in islets. Insulin treatment was associated with the nuclear localization of Pdx1 and the prosurvival effects of insulin were largely absent in islets 50% deficient in Pdx1, providing direct evidence that Pdx1 is a signaling target of insulin. Physiological levels of insulin did not increase Akt phosphorylation, and the protective effects of insulin were only partially altered in islets lacking 80% of normal Akt activity, suggesting the presence of additional insulin-regulated antiapoptotic pathways. Proteomic analysis of insulin-treated human islets revealed significant changes in multiple proteins. Bridge-1, a Pdx1-binding partner and regulator of beta-cell survival, was increased significantly at low insulin doses. Together, these data suggest that insulin can act as a master regulator of islet survival by regulating Pdx1.

A role for cathepsin E in the processing of mast-cell carboxypeptidase A

Mast-cell carboxypeptidase A is stored in the secretory granule and is released, together with a range of other inflammatory mediators, upon mast-cell degranulation. Carboxypeptidase A, like all mast-cell proteases, is stored in the granule as an active enzyme (i.e. with its propeptide removed). Although the processing mechanisms for the other classes of mast-cell proteases (in particular the chymases) have been clarified to some extent, the processing of procarboxypeptidase A is poorly characterized. Here, we show that mast cells from mice lacking the aspartic protease cathepsin E display an accumulation of procarboxypeptidase A, indicating a defect in carboxypeptidase-A processing. By contrast, mast cells lacking cathepsins B, L or D have normal carboxypeptidase-A processing. Furthermore, recombinant cathepsin E was found to process recombinant procarboxypeptidase A in vitro, under conditions resembling those found in mast-cell granules. Immunohistochemical analysis revealed staining for cathepsin E in mast cells from normal mice but not in mast cells from mice lacking heparin, indicating that cathepsin E is bound to heparin proteoglycan within mast-cell granules. In accordance with this notion, affinity chromatography showed that recombinant cathepsin E bound strongly to heparin under acidic conditions (the conditions prevailing in mast-cell granules) but not at neutral pH. Moreover, mast-cell degranulation resulted in the release of cathepsin E. Taken together, our results indicate that cathepsin E is located in mast-cell secretory granules in complex with heparin proteoglycans, and that it has a role in the processing of procarboxypeptidase A into active protease.

Gene Expression Profiling of Progressive Papillary Noninvasive Carcinomas of the Urinary Bladder

PURPOSE

The aim of the present study was to define gene expression profiles of noninvasive and invasive bladder cancer, to identify potential therapeutic or screening targets in bladder cancer, and to define genetic changes relevant for tumor progression of recurrent papillary bladder cancer (pTa).

EXPERIMENTAL DESIGN

Overall, 67 bladder neoplasms (46 pTa, 3 pTis, 10 pT1, and 8 pT2) and eight normal bladder specimens were investigated by a combination of laser microdissection and gene expression profiling. Eight of 16 patients with recurrent noninvasive papillary bladder tumors developed carcinoma in situ (pTis) or invasive bladder cancer (> or = pT1G2) in the course of time. RNA expression results of the putative progression marker cathepsin E (CTSE) were confirmed by immunohistochemistry using high-throughput tissue microarray analysis (n = 776). Univariate analysis of factors regarding overall survival, progression-free survival, and recurrence-free survival in patients with urothelial bladder cancer was done.

RESULTS

Hierarchical cluster analyses revealed no differences between pTaG1 and pTaG2 tumors. However, distinct groups of invasive cancers with different gene expression profiles in papillary and solid tumors were found. Progression-associated gene profiles could be defined (e.g., FABP4 and CTSE) and were already present in the preceding noninvasive papillary tumors. CTSE expression (P = 0.003) and a high Ki-67 labeling index of at least 5% (P = 0.01) were the only factors that correlated significantly with progression-free survival of pTa tumors in our gene expression approach.

CONCLUSIONS

Gene expression profiling revealed novel genes with potential clinical utility to select patients that are more likely to develop aggressive disease.

Processing of chicken progastrin at post-Phe bonds by an aspartyl protease

Prohormones mature to biologically active peptide hormones through posttranslational modifications, which include endoproteolytic cleavages. Cleavages at mono- and dibasic sites are well characterized, and several of the responsible prohormone convertases have been identified. There is, however, evidence that endoproteolytic maturation occurs also at other sites. Among these, post-Phe cleavage occurs in the maturation of chicken progastrin, where the processing to gastrin-30 has been examined in detail. In this study we have characterized an endoprotease of the aspartic acid protease family in chicken and human tissue capable of cleaving at the Phe site. Enzymatic activity was monitored by radioimmunoassays using antibodies specific for the N- and C-termini exposed after cleavage. Analysis showed that only pepstatin, a specific inhibitor of aspartic proteases, inhibited the enzyme. The pH optimum of the enzyme ranged from pH 2 to pH 5. Amino acid substitution from Phe to Ala in the substrate completely abolished enzyme activity. The endoproteolytic activity was identified in chicken antrum and pectoral muscle as well as human cardiac and prostate extracts, suggesting that the enzyme has widespread biological functions. Experiments using recombinant cathepsin D and E indicated that neither is responsible for the endoproteolytic cleavage of chicken progastrin at post-Phe bonds.

Expression of hypoxia-inducible factor 1alpha and cathepsin D in pituitary adenomas

Hypoxia-inducible factor (HIF)-1alpha is a crucial transcription factor involved in the adaptive response to hypoxia, whereas cathepsin D, which regulates angiostatin in several cancer cell lines, has been reported to be upregulated by HIF-1alpha. In order to determine the involvement of angiogenesis in pituitary adenomas, we studied the expression of both HIF-1alpha and cathepsin D in tissues from 58 patients (39 women, 19 men, ranging in age from 20 to 78 yr), sorted by histological group, and assayed by double immunohistochemistry. HIF-1alpha immunoreactivity, confined to the nucleoplasm, was present in both tumor and vascular endothelial cells. There was no difference in microvascular density (p = 0.7761) by histotype. ACTH-producing adenomas showed the lowest level of HIF-1alpha, whereas prolactin (PRL)-producing adenomas and HIF-1alpha-positive microvessels showed the highest (p < 0.001). In contrast, the lowest expression of cathepsin D was observed in PRL-producing adenomas, whereas the highest expression was detected in ACTH-producing adenomas (p < 0.0001). Imaging analysis with fluorescence double immunohistochemistry showed that HIF-1alpha-negative tumor cells did not express significantly higher levels of cathepsin D. In these poorly vascularized tumors, the hypoxic marker HIF-1alpha may not downregulate cathepsin D. The mechanisms of tumor angiogenesis and cell invasion in pituitary adenomas may differ from those in other tumor cells.

Cathepsin D is up-regulated in inflammatory bowel disease macrophages

Down-regulation of receptors involved in the recognition or transmission of inflammatory signals and a reduced responsiveness support the concept that macrophages are 'desensitized' during their differentiation in the intestinal mucosa. During inflammatory bowel disease (IBD) intestinal macrophages (IMACs) change to a reactive or 'aggressive' type. After having established a method of isolation and purification of IMACs, message for cathepsin D was one of the mRNAs we found to be up-regulated in a subtractive hybridization of Crohn's disease (CD) macrophages versus IMACs from control mucosa. The expression of cathepsin D in intestinal mucosa was analysed by immunohistochemistry in biopsies from IBD and control patients and in a mouse model of dextran sulphate sodium (DSS)-induced acute and chronic colitis. IMACs were isolated and purified from normal and inflamed mucosa by immunomagnetic beads armed with a CD33 antibody. RT-PCR was performed for cathepsin D mRNA. Results were confirmed by Northern blot and flow cytometrical analysis. Immunohistochemistry revealed a significant increase in the cathepsin D protein expression in inflamed intestinal mucosa from IBD patients compared to non-inflamed mucosa. No cathepsin D polymerase chain reaction (PCR) product could be obtained with mRNA from CD33-positive IMACs from normal mucosa. Reverse transcription (RT)-PCR showed an induction of mRNA for cathepsin D in purified IMACs from IBD patients. Northern blot and flow cytometry analysis confirmed these results. Cathepsin D protein was also found in intestinal mucosa in acute and chronic DSS-colitis but was absent in normal mucosa. This study shows that expression of cathepsin D is induced in inflammation-associated IMACs. The presence of cathepsin D might contribute to the mucosal damage in IBD.

Gene expression profiling reveals multiple toxicity endpoints induced by hepatotoxicants

Microarray technology continues to gain increased acceptance in the drug development process, particularly at the stage of toxicology and safety assessment. In the current study, microarrays were used to investigate gene expression changes associated with hepatotoxicity, the most commonly reported clinical liability with pharmaceutical agents. Acetaminophen, methotrexate, methapyrilene, furan and phenytoin were used as benchmark compounds capable of inducing specific but different types of hepatotoxicity. The goal of the work was to define gene expression profiles capable of distinguishing the different subtypes of hepatotoxicity. Sprague-Dawley rats were orally dosed with acetaminophen (single dose, 4500 mg/kg for 6, 24 and 72 h), methotrexate (1mg/kg per day for 1, 7 and 14 days), methapyrilene (100mg/kg per day for 3 and 7 days), furan (40 mg/kg per day for 1, 3, 7 and 14 days) or phenytoin (300 mg/kg per day for 14 days). Hepatic gene expression was assessed using toxicology-specific gene arrays containing 684 target genes or expressed sequence tags (ESTs). Principal component analysis (PCA) of gene expression data was able to provide a clear distinction of each compound, suggesting that gene expression data can be used to discern different hepatotoxic agents and toxicity endpoints. Gene expression data were applied to the multiplicity-adjusted permutation test and significantly changed genes were categorized and correlated to hepatotoxic endpoints. Repression of enzymes involved in lipid oxidation (acyl-CoA dehydrogenase, medium chain, enoyl CoA hydratase, very long-chain acyl-CoA synthetase) were associated with microvesicular lipidosis. Likewise, subsets of genes associated with hepatotocellular necrosis, inflammation, hepatitis, bile duct hyperplasia and fibrosis have been identified. The current study illustrates that expression profiling can be used to: (1) distinguish different hepatotoxic endpoints; (2) predict the development of toxic endpoints; and (3) develop hypotheses regarding mechanisms of toxicity.

Expression profiling of breast cancer cells by differential peptide display

Expression profiling of RNAs or proteins has become a promising means to investigate the heterogeneity of histopathologically defined classes of cancer. Peptides, representing degradation as well as processing products of proteins offer an even closer insight into cell physiology. Peptides are related to the turnover of cellular proteins and are capable to reflect disease-related changes in homoeostasis of the human body. Furthermore, peptides derived from tumor cells are potentially useful markers in the early detection of cancer. In this study, we introduced a method called differential peptide display (DPD) for separating, detecting, and identifying native peptides derived from whole cell extracts. This method is a highly standardized procedure, combining the power of reversed-phase chromatography with mass spectrometry. This technology is suitable to analyze cell lines, various tissue types and human body fluids. Peptide-based profiling of normal human mammary epithelial cells (HMEC) and the breast cancer cell line MCF-7 revealed complex peptide patterns comprising of up to 2300 peptides. Most of these peptides were common to both cell lines whereas about 8% differed in their abundance. Several of the differentially expressed peptides were identified as fragments of known proteins such as intermediate filament proteins, thymosins or Cathepsin D. Comparing cell lines with native tumors, overlapping peptide patterns were found between HMEC and a phylloides tumor (CP) on the one hand and MCF-7 cells and tissue from a invasive ductal carcinoma (DC) on the other hand.

[Cytosolic cathepsin D levels in squamous carcinomas of the lung]

BACKGROUND AND OBJECTIVES

Cathepsin D is an aspartyl proteinase involved in tumoral invasion. The aim of this work was to study cathepsin D cytosolic levels in squamous carcinomas of the lung and their correlation with several clinical and biological parameters.

PATIENTS AND METHOD

The study group included 95 squamous lung carcinomas and 38 normal tissue samples from the same patients. Cathepsin D cytosolic concentrations were determined using an immunoradiometric assay (CIS BioInternational. France). EGFR, erbB2 protein, CD44s, CD44v5 and CD44v6 levels at cell surfaces were determined. The clinical stage, histological grade, ploidy and S-phase cellular fraction (SP) were also considered as variables of the study.

RESULTS

Cathepsin D cytosolic levels oscillated between 7.7 and 576 (median: 38.8) pmol/mg protein and were lower (p = 0.001) than those observed in 38 normal lung samples from the same patients. When tumors were classified according to different clinical and biological parameters, we noticed that cathepsin D levels were higher in carcinomas with lower proliferation rates and no nodal involvement, reaching statistical significance in both cases. Moreover, when lung carcinomas were classified according to cathepsin D concentrations, tumors with higher cathepsin D concentrations had lower EGFR levels (p = 0.011) and small global SP values (p = 0.025) and DNA index (p = 0.023). Likewise, they were found to be CD44s positive more frequently (p = 0.001) and SP positive less frequently (p = 0.022).

CONCLUSIONS

These results lead us to suggest the following: a) in squamous carcinomas of the lung, cathepsin D cytosolic levels are lower than those observed in normal lung samples from the same patients, and b) in this subtype of lung carcinomas, high cathepsin D levels are associated with tumors without nodal involvement, with low proliferation rates, lower EGFR levels, and a reduced positivity for CD44s, pointing to a possible role of this proteinase as a parameter of good outcome.

Cathepsin-D affects multiple tumor progression steps in vivo: proliferation, angiogenesis and apoptosis

Cathepsin-D is an independent marker of poor prognosis in human breast cancer. We previously showed that human wild-type cathepsin-D, as well as its mutated form devoid of proteolytic activity stably transfected in 3Y1-Ad12 cancer cells, stimulated tumor growth. To investigate the mechanisms by which human cathepsin-D and its catalytically-inactive counterpart promoted tumor growth in vivo, we quantified the expression of proliferating cell nuclear antigen, the number of blood vessels and of apoptotic cells in 3Y1-Ad12 tumor xenografts. We first verified that both human wild-type and mutated cathepsin-D were expressed at a high level in cathepsin-D xenografts, whereas no human cathepsin-D was detected in control xenografts. Our immunohistochemical studies then revealed that both wild-type cathepsin-D and catalytically-inactive cathepsin-D, increased proliferating cell nuclear antigen expression and tumor angiogenesis. Interestingly, wild-type cathepsin-D significantly inhibited tumor apoptosis, whereas catalytically-inactive cathepsin-D did not. We therefore propose that human cathepsin-D stimulates tumor growth by acting-directly or indirectly-as a mitogenic factor on both cancer and endothelial cells independently of its catalytic activity. Our overall results provide the first mechanistic evidences on the essential role of cathepsin-D at multiple tumor progression steps, affecting cell proliferation, angiogenesis and apoptosis.

Neurodegenerative disease: the neuronal ceroid lipofuscinoses (Batten disease)

In the past decade there have been significant advances in our understanding of the molecular genetic basis of the neuronal ceroid lipofuscinoses, a clinically and genetically heterogeneous group of childhood neurodegenerative storage disorders. Recent research progress is reviewed here, to summarize new disease gene identification, diagnostics, treatment, protein functional studies and investigations into the underlying molecular pathogenesis of these devastating disorders.