Micro-lymph node metastasis and its correlation with cathepsin D expression in early gastric cancer

Cathepsin D promotes polarization of tumor-associated macrophages and metastasis through TGFBI-CCL20 signaling

M2-like tumor-associated macrophages (TAMs) are risk factors for cancer progression and metastasis. However, the mechanisms underlying their polarization are still not fully understood. Although cathepsin D (Cat D) has been reported as a procarcinogenic factor, little is known about the functional role of Cat D in the tumor microenvironment (TME). This study aimed to explore the effect and molecular mechanisms of Cat D in the TME. Cat D knockout (KO) altered the cytokine secretion pattern and induced TAM reprogramming from the M2 to M1 subtype, thereby preventing epithelial-mesenchymal transition and tumor metastasis. Mechanistically, we identified transforming growth factor beta-induced protein (TGFBI) as a Cat D target protein that is specifically associated with TAM polarization. Elevated TGFBI expression in Cat D KO cancer cells resulted in a decline in M2-like TAM polarization. Our RNA-sequencing results indicated that the cancer cell-secreted chemokine CCL20 is a major secretory chemokine for Cat D-TGFBI-mediated TAM polarization. In contrast, Cat D overexpression accelerated TAM polarization into M2-like cells by suppressing TGFBI expression. In addition, the double Cat D and TGFBI KO rescued the inhibitory effects of Cat D KO on tumor metastasis by controlling TAM and T-cell activation. These findings indicated that Cat D contributes to cancer metastasis through TGFBI-mediated TAM reprogramming. Cat D deletion inhibits M2-like TAM polarization through TGFBI-mediated CCL20 expression, reprogramming the immunosuppressive TME. Our results open a potential new avenue for therapy focused on eliminating tumor metastasis.

Role of lysosomes in physiological activities, diseases, and therapy

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

Cathepsin L promotes angiogenesis by regulating the CDP/Cux/VEGF-D pathway in human gastric cancer

BACKGROUND

Increasing evidence indicates that angiogenesis plays an important role in tumor progression. The function of cathepsin L (CTSL), an endosomal proteolytic enzyme, in promoting tumor metastasis is well recognized. The mechanisms by which CTSL has promoted the angiogenesis of gastric cancer (GC), however, remains unclear.

METHODS

The nuclear expression levels of CTSL were assessed in GC samples. The effects of CTSL on GC angiogenesis were determined by endothelial tube formation analysis, HUVEC migration assay, and chick embryo chorioallantoic membrane (CAM) assay. The involvement of the CDP/Cux/VEGF-D pathway was analyzed by angiogenesis antibody array, Western blot, co-immunoprecipitation (Co-IP) and dual-luciferase reporter assay.

RESULTS

In this study, we found that the nuclear CTSL expression level in GC was significantly higher than that in adjacent nontumor gastric tissues and was a potential important clinical prognostic factor. Loss- and gain-of-function assays indicated that CTSL promotes the tubular formation and migration of HUVEC cells in vitro. The CAM assay also showed that CTSL promotes angiogenesis of GC in vivo. Mechanistic analysis demonstrated that CTSL can proteolytically process CDP/Cux and produce the physiologically relevant p110 isoform, which stably binds to VEGF-D and promotes the transcription of VEGF-D, thus contributing to the angiogenesis of GC.

CONCLUSION

The findings of the present study suggested that CTSL plays a constructive role in the regulation of angiogenesis in human GC and could be a potential therapeutic target for GC.

Cathepsins in digestive cancers

Cathepsins are lysosomal peptidases belonging to the papain family, and based on their catalytic sites, these enzymes can be divided into serine, cysteine and aspartic proteases. The studies conducted to date have identified, 15 types of cathepsins that are widely distributed in intracellular and extracellular spaces. These proteases participate in various pathological activities, including the occurrence and development of human cancers. Several recent studies suggest that cathepsins, particularly cathepsins B, D, E and L, contribute to digestive tumorigenesis. Cathepsins were found to promote the development of most digestive cancers except liver cancer, in which they might have the opposite effects. Due to their important roles in digestive tumors, cathepsins might be therapeutic targets for the treatment of digestive cancers.

Significance of elevated levels of collagen type IV and hyaluronic acid in gastric juice and serum in gastric cancer and precancerous lesion

BACKGROUND AND AIMS

Collagen type IV and hyaluronic acid (HA) are the major components of basement membrane and extracellular matrix, respectively. Cathepsin D is an aspartyl lysosomal protease involved in the degradation of the basement membrane and extracellular matrix. The aim of this study is to investigate the clinical significance of collagen type IV and hyaluronic acid in gastric juice and serum in diagnosis of gastric cancer and the degrading effect of cathepsin D on collagen type IV and HA.

METHODS

Fifty gastric cancer patients were enrolled in our study compared with 41 patients with precancerous lesion and 30 control subjects. Collagen type IV and HA in gastric juice and serum were analyzed by radioimmunoassay. Expression of cathepsin D and collagen type IV in tissue were analyzed by immunohistochemical staining with monoclonal antibodies.

RESULTS

The contents of collagen type IV and HA in gastric juice and HA in serum were significantly higher in patients with gastric cancer than those in patients with precancerous lesion and control group (p < 0.05, p < 0.0001). Gastric cancer patients with lymph node metastasis had a higher level of collagen type IV and HA in gastric juice than those in patients without metastasis (p = 0.049, p = 0.043). The expression of cathepsin D had significantly increased in patients with gastric cancer compared to the control group (p < 0.0001). The continuous expression of collagen type IV in basement membrane in gastric cancer group was lower than that in the precancerous lesion group and control group (p < 0.0001).

CONCLUSIONS

The analysis of collagen type IV and HA in gastric juice and serum may provide a simple aid in diagnosing gastric cancer and evaluating whether metastasis is occurring or not.

Proteomic analysis of human mesenchymal stem cells

Umbilical cord (UC) and placenta (P) are generally believed to be potential alternatives to bone marrow (BM), as sources of mesenchymal stem cells (MSC) for cell therapy. They possess immunophenotypic and functional characteristics which are similar to that of BM-MSC, yet one of the crucial factors in determining the tissue regeneration process--the migration capacity--is still unclear. In our previous study, the migration capacity of BM- and P-MSC was found 5.9- and 3.2-fold higher than that of UC-MSC, respectively. By using 2-dimensional gel electrophoresis (2-DE) and combined MS and MS/MS analysis, six proteins were identified as differentially expressed among these MSC samples. Five out of the six proteins were known to be involved in cell migration as migration inhibiting or enhancing proteins.

Comparative proteomic analysis of mesenchymal stem cells derived from human bone marrow, umbilical cord and placenta: implication in the migration

Umbilical cord (UC) and placenta (P) have been suggested as alternatives to bone marrow (BM) as sources of mesenchymal stem cells (MSC) for cell therapy, with both UC- and P-MSC possess immunophenotypic and functional characteristics similar to BM-MSC. However, under defined conditions, the migration capacity of BM- and P-MSC was found to be 5.9- and 3.2-folds higher than that of UC-MSC, respectively. By the use of 2-DE and combined MS and MS/MS analysis, six differentially expressed proteins were identified among these MSC samples, with five of them known to be involved in cell migration as migration enhancing or inhibiting proteins. Interestingly, the expression levels of those proteins reflect perfectly the migration capacity of corresponding MSC, which is also proved by in vitro overexpression and silencing techniques. Our study indicates that a bunch of migration-related proteins are pivotal in governing the migration capacity of MSC.

Comparative proteomic analysis of mesenchymal stem cells derived from human bone marrow, umbilical cord, and placenta: implication in the migration

Umbilical cord (UC) and placenta (P) have been suggested as alternatives to bone marrow (BM) as sources of mesenchymal stem cells (MSC) for cell therapy, with both UC- and P-MSC possess immunophenotypic and functional characteristics similar to BM-MSC. However, their migration capacity, which is indispensable during tissue regeneration process, is unclear. Under defined conditions, the migration capacity of BM- and P-MSC was found 5.9- and 3.2-folds higher than that of UC-MSC, respectively. By the use of 2-DE and combined MS and MS/MS analysis, six differentially expressed proteins were identified among these MSC samples, with five of them known to be involved in cell migration as migration enhancing or inhibiting proteins. Consistent with their migration capacity, the levels of migration enhancing proteins including cathepsin B, cathepsin D and prohibitin,were significantly lower in UC-MSC when compared with those in BM- and P-MSC. For the migration inhibiting proteins such as plasminogen activator inhibitor-1 (PAI-1) and manganese superoxide dismutase, higher expression was found in the UC-MSC. We also showed that the overexpression of the PAI-1 impaired the migration capacity of BM- and P-MSC while silencing of PAI-1 enhanced the migration capacity of UC-MSC. Our study indicates that PAI-1 and other migration-related proteins are pivotal in governing the migration capacity of MSC.

Endoscopic therapy of early gastric cancer

Endoscopic therapy of early gastric cancer is applicable for differentiated-type mucosal carcinomas that have an extremely low potency of lymph-node metastasis. Among various kinds of endoscopic therapy, endoscopic mucosal resection is the most recommended procedure, because pathological evaluation of affected tissues is available using this method. Recently, endoscopic submucosal dissection, a novel method of endoscopic mucosal resection, has gained interest as a more reliable therapeutic procedure. In the present chapter several issues will be presented on endoscopic therapy for early gastric cancer, including endoscopic diagnosis of early gastric cancer, currently accepted indications of endoscopic therapy, and the possibility of extending the indication and techniques used for mucosal resection.

Prognostic value of cytosolyc cathepsin D content in resectable gastric cancer

BACKGROUND AND AIMS

Cathepsin D (Cath-D) is an aspartyl protease involved in protein catabolism and tissue remodelling. In the present article, we evaluate the tumor content of Cath-D in resectable gastric carcinomas and its relation with clinical and pathological parameters, as well as its prognostic significance.

METHOD

This prospective study included a series of 60 patients with primary gastric adenocarcinoma, who first underwent a complete surgical resection of their tumors and then were evaluated for disease recurrence and survival status during a mean follow-up period of 41.5 months. Cath D was measured in cytosolic samples using an immune-radiometric assay which determined the total amount of Cath-D (52K, 48K, and 34K).

RESULTS

The tumor content of Cath-D ranged from 4 to 247 pmol/mg protein and from 6.4 to 97.7 pmol/mg protein in adjacent non-neoplastic mucosa samples. Cytosolic Cath-D levels were significantly higher in neoplastic tissues (P < 0.001). Statistical analysis also demonstrated that younger patients showed lower Cath-D tumor levels than older ones. Likewise, patients with lower tumor levels of Cath-D had better survival than those with intermediate or high Cath-D tumor content (P = 0.002). This finding showed an independent prognostic value on survival (P = 0.02).

CONCLUSIONS

The present study demonstrates the presence of higher Cath-D content in gastric carcinomas than in adjacent non-neoplastic mucosa, and that high intratumor Cath-D levels identify a subgroup of resectable gastric cancer patients with a high probability of relapse as well as worse survival.

Procathepsin D in breast cancer: what do we know? Effects of ribozymes and other inhibitors

Procathepsin D (pCD) is a major secreted glycoprotein in some human breast and other cancer cell lines. Several groups proposed that pCD served as a growth factor for these cell lines. Secreted pCD has been demonstrated in tissue section, tissue culture supernatants, carcinoma cytosols, and nipple aspirates. Moreover, several clinical studies suggested a potential role for this molecule in metastasis because its concentration in primary tumors correlated with an increased incidence of tumor metastases. In this paper, the effects of pCD were evaluated by proliferation in vitro and by mouse studies in vivo. Subsequent flow cytometry experiments showed the specificity of pCD binding to cancer cells. Cell cultivation showed that addition of either pCD or its activation peptide stimulates growth of cancer cells. These effects can be inhibited both in vitro and in vivo by anti-pCD antibodies. In addition, production of pCD can be inhibited by specifically designed ribozymes. This paper is focused on mitogenic effects of pCD, which seem to involve interaction of the activation peptide with as yet unidentified receptor. Different mechanisms by which pCD could promote development and spread of cancer cells are discussed.