Cystatin C Deficiency Promotes Epidermal Dysplasia in K14-HPV16 Transgenic Mice

Cysteine protease cathepsins are important in extracellular matrix protein degradation, cell apoptosis, and angiogenesis. Mice lacking cathepsins are protected from tumor progression in several animal models, suggesting that the regulation of cathepsin activities controls the growth of various malignant tumors.We tested the role of cathepsins using a mouse model of multistage epithelial carcinogenesis, in which the human keratin-14 promoter/enhancer drove the expression of human papillomavirus type 16 (HPV16) early region E6/E7 transgenes. During the progression of premalignant dysplasia, we observed increased expression of cysteine protease cathepsin S, but concomitantly reduced expression of cathepsin endogenous inhibitor cystatin C in the skin tissue extract. Absence of cystatin C in these transgenic mice resulted in more progression of dysplasia to carcinoma in situ on the face, ear, chest, and tail. Chest and ear skin extract real time PCR and immunoblot analysis, mouse serum sample ELISA, tissue immunohistological analysis, and tissue extract-mediated in vitro elastinolysis and collagenolysis assays demonstrated that cystatin C deficiency significantly increased cathepsin expression and activity. In skin from both the chest and ear, we found that the absence of cystatin C reduced epithelial cell apoptosis but increased proliferation. From the same tissue preparations, we detected significantly higher levels of pro-angiogenic laminin 5-derived γ2 peptides and concurrently increased neovascularization in cystatin C-deficient mice, compared to those from wild-type control mice.Enhanced cathepsin expression and activity in cystatin C-deficient mice contributed to the progression of dysplasia by altering premalignant tissue epithelial proliferation, apoptosis, and neovascularization

Immunochemical analysis of cathepsin B in lung tumours: an independent prognostic factor for squamous cell carcinoma patients

In order to evaluate the possible role of the proteolytic enzyme cathepsin B (cath B) in human non-small cell lung cancer (NSCLC) we examined cath B concentrations (cath Bc) and activities (cath BA) in homogenates of 127 pairs of lung tumour tissues and corresponding non-tumourous lung parenchyma. Total cath B activity (cath BAT) and enzymatic activity of the fraction of cath B, which is stable and active at pH 7.5 (cath BA7.5) were determined by a fluorogenic assay using synthetic substrate Z-Arg-Arg-AMC. The immunostaining pattern of cath B was determined in 239 lung tumour tissue sections, showing the presence of the enzyme in tumour cells (cath BT-I) and in tumour-associated histiocytes (cath BH-I). The median levels of cath BAT, cath BA7.5 and cath BC were 5.6-, 3.2- and 9.1-fold higher (P < 0.001), respectively, in tumour tissue than in non-tumourous lung parenchyma. Out of 131 tissue sections from patients with squamous cell carcinoma (SCC), 59.5% immunostained positively for cath B, while among the 108 adenocarcinoma (AC) patients 48.2% of tumours showed a positive reaction. There was a strong relationship between the levels of cath BAT, cath BA7.5, cath BC and cath BT-I in the primary tumours and the presence of lymph node metastases. Significant correlation with overall survival was observed for cath BT-I and cath BA7.5 (P < 0.01 and P < 0.05, respectively) in patients suffering from SCC. In these patients positive cath B in tumour cells (cath BT-I) and negative cath B in histiocytes (cath BH-I) indicated significantly shorter survival rate compared with patients with negative cath BT-I and positive cath BH-I (P < 0.0001). In contrast, in AC patients, both, positive cath BT-I and positive cath BH-I, indicated poor survival probability (P < 0.014). From these results we conclude that the proteolytic enzyme cath B is an independent prognostic factor for overall survival of patients suffering from SCC of the lung. © 1999 Cancer Research Campaig

Apoptosis in cancer: from pathogenesis to treatment

Apoptosis is an ordered and orchestrated cellular process that occurs in physiological and pathological conditions. It is also one of the most studied topics among cell biologists. An understanding of the underlying mechanism of apoptosis is important as it plays a pivotal role in the pathogenesis of many diseases. In some, the problem is due to too much apoptosis, such as in the case of degenerative diseases while in others, too little apoptosis is the culprit. Cancer is one of the scenarios where too little apoptosis occurs, resulting in malignant cells that will not die. The mechanism of apoptosis is complex and involves many pathways. Defects can occur at any point along these pathways, leading to malignant transformation of the affected cells, tumour metastasis and resistance to anticancer drugs. Despite being the cause of problem, apoptosis plays an important role in the treatment of cancer as it is a popular target of many treatment strategies. The abundance of literature suggests that targeting apoptosis in cancer is feasible. However, many troubling questions arise with the use of new drugs or treatment strategies that are designed to enhance apoptosis and critical tests must be passed before they can be used safely in human subjects