Cathepsin-D in primary breast cancer: prognostic evaluation involving 2810 patients

Estrogen receptor (ER) beta1 and ERbetacx/beta2 inhibit ERalpha function differently in breast cancer cell line MCF7

Estrogen receptor (ER) alpha plays an important role in the proliferation and progression of breast cancer. In order to explore the function of wild-type ERbeta (ERbeta1) and its variant form, ERbetacx/beta2, stable transformants of ERalpha-positive breast cancer MCF7 cells with ERbeta1 or ERbetacx/beta2 expression vector were established. Constitutive expression of ERbeta1 or ERbetacx/beta2 reduced the S phase population of the cell cycle in dish culture and the number of colonies in an anchorage-independent assay. DNA-protein complexes of ERE with nuclear extracts from ERbeta1 transformants were observed in the electrophoretic mobility shift assay, while no complex was observed for ERbetacx/beta2 transformants. Reporter gene assay using estrogen-responsive element (ERE)-luciferase showed less responsiveness to estrogen in these transformants compared with parental cells. Endogenous mRNA expression of two known estrogen-responsive genes, cathepsin D and IGFBP4, was weakly induced by estrogen in ERbeta1 and ERbetacx/beta2 transformants compared with parental cells. A comprehensive gene expression analysis using our custom-made cDNA microarray showed that MCF7 and ERbeta1 transformants had a similar gene expression profile, whereas ERbetacx/beta2 showed a distinct profile from others. These results indicate that ERbeta1 and ERbetacx/beta2 inhibit ERalpha function differently in MCF7 cells.

Aspartic proteinase napsin is a useful marker for diagnosis of primary lung adenocarcinoma

Napsin A is an aspartic proteinase expressed in lung and kidney. We have reported that napsin A is expressed in type II pneumocytes and in adenocarcinomas of the lung. The expression of napsin was examined in 118 lung tissues including 16 metastases by in situ hybridisation. Napsin was expressed in the tumour cell compartment in 33 of 39 adenocarcinomas (84.6%), in two of 11 large cell carcinomas and in one lung metastasis of a renal cell carcinoma. Expression of napsin was found to be associated with a high degree of differentiation in adenocarcinoma. Immunohistochemistry was performed for three proteins currently used as markers for lung adenocarcinoma : surfactant protein-A, surfactant protein-B and thyroid transcription factor-1. Thyroid transcription factor-1 showed the same sensitivity (84.6%) as napsin for adenocarcinoma, whereas surfactant protein-A and surfactant protein-B showed lower sensitivities. Among these markers, napsin showed the highest specificity (94.3%) for adenocarcinoma in nonsmall cell lung carcinoma. We conclude that napsin is a promising marker for the diagnosis of primary lung adenocarcinoma.

Cathepsin D specifically cleaves the chemokines macrophage inflammatory protein-1 alpha, macrophage inflammatory protein-1 beta, and SLC that are expressed in human breast cancer

Cathepsin D (Cath-D) expression in human primary breast cancer has been associated with a poor prognosis. In search of a better understanding of the Cath-D substrates possibly involved in cancer invasiveness and metastasis, we investigated the potential interactions between this protease and chemokines. Here we report that purified Cath-D, as well as culture supernatants from the human breast carcinoma cell lines MCF-7 and T47D, selectively degrade macrophage inflammatory protein (MIP)-1 alpha (CCL3), MIP-1 beta (CCL4), and SLC (CCL21). Proteolysis was totally blocked by the protease inhibitor pepstatin A, and specificity of Cath-D cleavage was demonstrated using a large chemokine panel. Whereas MIP-1 alpha and MIP-1 beta degradation was rapid and complete, cleavage of SLC was slow and not complete. Mass spectrometry analysis showed that Cath-D cleaves the Leu(58) to Trp(59) bond of SLC producing two functionally inactive fragments. Analysis of Cath-D proteolysis of a series of monocyte chemoattractant protein-3/MIP-1 beta hybrids indicated that processing of MIP-1 beta might start by cleaving off amino acids located in the C-terminal domain. In situ hybridization studies revealed MIP-1 alpha, MIP-1 beta, and Cath-D gene expression mainly in the stromal compartment of breast cancers whereas SLC transcripts were found in endothelial cells of capillaries and venules within the neoplastic tissues. Cath-D production in the breast carcinoma cell lines MCF-7 and T47D, as assessed by enzyme-linked immunosorbent assay of culture supernatants and cell lysates, was not affected by stimulation with chemokines such as interleukin-8 (CXCL8), SDF-1 (CXCL12), and SLC. These data suggest that inactivation of chemokines by Cath-D possibly influences regulatory mechanisms in the tumoral extracellular microenvironment that in turn may affect the generation of the antitumoral immune response, the migration of cancer cells, or both processes.

Mannose-6-phosphate/insulin-like growth factor-II receptor expression levels during the progression from normal human mammary tissue to invasive breast carcinomas

The putative role of mannose-6-phosphate/insulin-like growth factor-II receptor (M6P/IGFII-R) as a tumour suppressor and its value as a prognostic marker of breast cancer was studied in 42 benign breast diseases (BBD), 61 in situ carcinomas (CIS) and 133 invasive carcinomas. The receptor was quantified by immunohistochemistry with a computerised image analyser, using specific polyclonal IGY antibodies. The M6P/IGFII-R level varied markedly according to the different patient samples, but median values and distributions were similar in lesions and normal adjacent glands. However, the receptor level was significantly increased in high-grade ductal carcinomas in situ (DCIS) and decreased in invasive carcinomas relative to adjacent normal tissue. The M6P/IGFII-R protein concentration in invasive breast carcinomas was mostly independent of prognostic parameters: tumour size, histological grade, lymph node (N) invasiveness and oestrogen receptor alpha (ERalpha) status. The only positive correlation was with cathepsin D, the progesterone receptor (PgR) and with patients aged >60 years. These results do not support the hypothesis of a frequent and early inactivation of the M6P/IGFII-R gene in breast cancer. Clinical follow-up of patients might reveal a prognostic value for one of the cathepsin receptors.

[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.

Immunohistochemical expression of uPA, PAI-1, cathepsin D and apoptotic cells in ductal carcinoma in situ of the breast

BACKGROUND

We examined the relationship between biological markers, apoptotic indices and pathologic subtypes of ductal carcinoma in situ (DCIS) of the breast. The tumor-biological factors can be divided into invasive and proliferative markers. We chose urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor type 1 (PAI-1) and Cathepsin D as invasive markers, and Ki-67 and C-erbB2 oncoproteins as proliferative factors for our study.

METHODS

We used immunohistochemical methods to investigate the expression of uPA, PAI-1, Cathepsin D, Ki-67, C-erbB2 and ssDNA (single-stranded DNA for apoptotic cells) in 20 cases of DCIS. Tumor histological grade and the immunohistochemical expression of invasive and proliferative markers were compared.

RESULTS

Histological grade is associated with C-erbB2, MIB-1, apoptotic index (AI) and expression of PAI-1 in cancer and stroma. The correlation coefficient of the MIB-1 index and AI was 0.867. Of these invasive markers, only expression of PAI-1 in tumor and in stroma was associated with C-erbB2.

CONCLUSION

Our results show that the apoptosis index is closely related to the MIB-1 index, and also suggest that the immunohistochemical detection of PAI-1 in the cytoplasm of both carcinoma cells and stromal cells of DCIS is related to histological grade and expression of the proliferative markers MIB-1 and C-erbB2. Therefore, we infer that both invasiveness and proliferation are affected by the tumorigenesis of DCIS.

Interaction of human breast fibroblasts with collagen I increases secretion of procathepsin B

Interactions of stromal and tumor cells with the extracellular matrix may regulate expression of proteases including the lysosomal proteases cathepsins B and D. In the present study, we determined whether the expression of these two proteases in human breast fibroblasts was modulated by interactions with the extracellular matrix component, collagen I. Breast fibroblasts were isolated from non-malignant breast tissue as well as from tissue surrounding malignant human breast tumors. Growth of these fibroblasts on collagen I gels affected cell morphology, but not the intracellular localization of vesicles staining for cathepsin B or D. Cathepsins B and D levels (mRNA or intracellular protein) were not affected in fibroblasts growing on collagen I gels or plastic, nor was cathepsin D secreted from these cells. In contrast, protein expression and secretion of cathepsin B, primarily procathepsin B, was induced by growth on collagen I gels. The induced secretion appeared to be mediated by integrins binding to collagen I, as inhibitory antibodies against alpha(1), alpha(2), and beta(1) integrin subunits prevented procathepsin B secretion from fibroblasts grown on collagen. In addition, procathepsin B secretion was induced when cells were plated on beta(1) integrin antibodies. To our knowledge, this is the first examination of cathepsin B and D expression and localization in human breast fibroblasts and their regulation by a matrix protein. Secretion of the cysteine protease procathepsin B from breast fibroblasts may have physiological and pathological consequences, as proteases are required for normal development and for lactation of the mammary gland, yet can also initiate and accelerate the progression of breast cancer.

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.

Down-regulation of cathepsin-D expression by antisense gene transfer inhibits tumor growth and experimental lung metastasis of human breast cancer cells

Overexpression of cathepsin-D in primary breast cancer has been associated with rapid development of clinical metastasis. To investigate the role of this protease in breast cancer growth and progression to metastasis, we stably transfected a highly metastatic human breast cancer cell line, MDA-MB-231, with a plasmid containing either the full-length cDNA for cathepsin-D or a 535 bp antisense cathepsin-D cDNA fragment. Clones expressing antisense cathepsin-D cDNA that exhibited a 70-80% reduction in cathepsin-D protein, both intra- and extracellularly compared to controls, were selected for further experiments. These antisense-transfected cells displayed a reduced outgrowth rate when embedded in a Matrigel matrix, formed smaller colonies in soft agar and presented a significantly decreased tumor growth and experimental lung metastasis in nude mice compared with controls. However, manipulating the cathepsin-D level in the antisense cells has no effect on their in vitro invasiveness. These studies demonstrate that cathepsin-D enhances anchorage-independent cell proliferation and subsequently facilitates tumorigenesis and metastasis of breast cancer cells. Our overall results provide the first evidence on the essential role of cathepsin-D in breast cancer, and support the development of a new cathepsin-D-targeted therapy.

Molecular prognostic indicators in breast cancer

Here we review a panel of oncogene products, proteases and markers of proliferation that have shown potential as prognostic indicators in primary breast cancer. The relative merits of specific genetic mutations as well as alterations at the protein level are discussed. Finally an assessment is made of the transfer of knowledge from the laboratory to the bed-side.

Procathepsin D interacts with prosaposin in cancer cells but its internalization is not mediated by LDL receptor-related protein

The cell surface binding, endocytosis, and lysosomal routing of procathepsin D (procath-D) in cancer cells are mostly independent of the mannose-6-phosphate (M6P) receptors. In an attempt to define the receptor involved, we intracellularly cross-linked procath-D with a 68-kDa protein that we identified with specific antibodies as prosaposin in human breast and ovarian cancer cell lines. In cancer cells, this protein-protein interaction was resistant to ammonium chloride or M6P treatment, indicating that it was independent of the M6P receptors. A similar interaction also occurred in the breast cancer cell culture medium between the secreted prosaposin and procath-D. Since these two precursors can be endocytosed, we then determined whether they were interacting with the same cell surface receptor. In fibroblasts, we confirmed that the endocytosis of these two proteins was different since it was generally mediated by the M6P receptors for procath-D and mostly by LRP (LDL receptor-related protein) for prosaposin. In breast cancer cells, prosaposin endocytosis was not detected, in contrast to procath-D endocytosis, suggesting that the majority of procath-D is not internalized as a complex with prosaposin. Moreover, RAP (receptor-associated protein), a ligand inhibiting LRP-mediated endocytosis, prevented internalization of prosaposin in 49-F rat fibroblasts, but did not affect procath-D M6P-independent internalization in MDA-MB231 cells. We conclude that in breast cancer cells, even though procath-D interacts intracellularly and extracellarly with prosaposin, it is endocytosed independent of prosaposin by a receptor different from the M6P receptors and the LRP.

Immunohistochemical cathepsin-D expression in breast cancer: correlation with established pathological parameters and survival

Breast cancer is an increasingly important cause of illness and death among women. In recent years, several novel prognostic determinants of breast cancer have been identified, including Cathepsin-D (CD) protein. CD protein expression was analyzed immunohistochemically (IHC) in tumor specimens (315 patients) of infiltrating ductal breast carcinoma. These patients also had axillary lymph node sampling. Overexpression of CD was observed in 39% of the tumors. IHC results were compared with the histological grade. Seventy nine percent (n = 95; 79%) tumor positivity was seen in grade II tumors, followed by grade I (n = 13; 11%) and grade III tumors (n = 12; 10%). Axillary lymph node metastasis had no significant correlation with CD positivity (p > 0.05). Bone metastases were significantly correlated with CD positivity (p < 0.05). CD positivity showed no significant correlation with disease-free and overall survival (p > 0.05). At a median follow-up of 48 (4 years) months in CD-positive patients, overall survival was 3.17 years, and disease-free survival 2.67 years. The overall survival of CD-negative tumor patients was 3.50 years, and disease-free survival was 2.93 years. We conclude that in comparison with cytosol-based quantitative studies, CD expression is not a good prognostic marker when, as in all ICH studies, only the expression in the tumor is considered.

Prognostic factors in node-negative breast cancer: a review of studies with sample size more than 200 and follow-up more than 5 years

OBJECTIVE

To review the published literature on prognostic factors in patients with node-negative breast cancer, focusing principally on recent studies with large sample sizes and extended follow-up periods.

SUMMARY BACKGROUND DATA

Although numerous studies have examined prognostic factors in patients with breast cancer, relatively few have dealt specifically with node-negative disease, and interpretation has been limited by small sample size and limited follow-up times.

METHODS

A review of the Medline database from 1996 to 2000 was undertaken, with additional papers published before 1996 identified through review articles. For inclusion in the analysis, papers needed to meet the following core criteria: 200 or more node-negative patients with invasive breast carcinoma; median follow-up time at least 5 years; method of testing and cut-off points specified; overall survival and/or disease-free survival specified; and relative risk or statistical probability values given for comparisons.

RESULTS

Three or more papers that met the core criteria were retrieved for each of 11 potential prognostic factors. Of these, tumor size, tumor grade, cathepsin-D, Ki-67, S-phase fraction, mitotic index, and vascular invasion showed a significant association with survival outcomes; HER2/neu and DNA ploidy showed no significant association; and estrogen receptor status and p53 showed mixed results. Lack of standardization in measurement techniques for many of the markers, including cathepsin-D, Ki-67, HER2/neu, and p53, limited their current clinical usefulness.

CONCLUSIONS

In large studies with extended follow-up periods, tumor size, tumor grade, cathepsin-D, Ki-67, S-phase fraction, mitotic index, and vascular invasion showed a significant association with survival outcome measures in patients with early-stage node-negative breast cancer. Because of technical difficulties and variations in the measurement of many of these factors, tumor size and tumor grade remain the only markers that currently have broad clinical usefulness for this patient group.

Gene expression patterns of breast carcinomas distinguish tumor subclasses with clinical implications

The purpose of this study was to classify breast carcinomas based on variations in gene expression patterns derived from cDNA microarrays and to correlate tumor characteristics to clinical outcome. A total of 85 cDNA microarray experiments representing 78 cancers, three fibroadenomas, and four normal breast tissues were analyzed by hierarchical clustering. As reported previously, the cancers could be classified into a basal epithelial-like group, an ERBB2-overexpressing group and a normal breast-like group based on variations in gene expression. A novel finding was that the previously characterized luminal epithelial/estrogen receptor-positive group could be divided into at least two subgroups, each with a distinctive expression profile. These subtypes proved to be reasonably robust by clustering using two different gene sets: first, a set of 456 cDNA clones previously selected to reflect intrinsic properties of the tumors and, second, a gene set that highly correlated with patient outcome. Survival analyses on a subcohort of patients with locally advanced breast cancer uniformly treated in a prospective study showed significantly different outcomes for the patients belonging to the various groups, including a poor prognosis for the basal-like subtype and a significant difference in outcome for the two estrogen receptor-positive groups.

A mutated cathepsin-D devoid of its catalytic activity stimulates the growth of cancer cells

Cathepsin-D, a lysosomal aspartyl proteinase, is highly secreted by breast cancer cells and its over-expression by transfection stimulates cancer cell proliferation. The mechanism by which this protease affects proliferation remains, however, unknown. In order to determine whether proteolytic activity is necessary, we abolished its enzymatic activity using site-directed mutagenesis followed by stable transfection in 3Y1-Ad12 cancer cells. Substitution of the aspartic acid residue 231 by an asparagine residue in its catalytic site abrogated the cathepsin-D proteolytic activity but did not affect its expression level, processing or secretion. However, like wild-type cathepsin-D, this mutated catalytically-inactive cathepsin-D retained its capacity to stimulate proliferation of cells embedded in Matrigel or collagen I matrices, colony formation in soft agar and tumor growth in athymic nude mice. Addition on the mock-transfected cells, of either conditioned media containing the wild-type or the mutated pro-cathepsin-D, or of the purified mutated pro-cathepsin-D, partially mimicked the mitogenic activity of the transfected cathepsin-D, indicating a role of the secreted pro-enzyme. Moreover, addition of two anti-cathepsin-D antibodies on the cathepsin-D transfected cells inhibited their proliferation, suggesting an action of the secreted pro-cathepsin-D via an autocrine loop. A synthetic peptide containing the 27-44 residue moiety of the cathepsin-D pro-fragment was, however, not mitogenic suggesting that a receptor for the pro-fragment was not involved. Furthermore, the cathepsin-D mitogenicity was not blocked by inhibiting the interaction of pro-cathepsin-D with the mannose-6-phosphate receptors. Our results altogether demonstrate that a mutated cathepsin-D devoid of catalytic activity is still mitogenic and suggest that it is acting extra-cellularly by triggering directly or indirectly a yet unidentified cell surface receptor.

May cathepsin D immunoreactivity be used as a prognostic factor in endometrial carcinomas? A comparative immunohistochemical study

OBJECTIVE

To investigate the prognostic value of immunohistochemical detection of cathepsin D and the association between cathepsin D and established prognostic factors in endometrial carcinoma.

METHODS

Cathepsin D immunoreactivity was determined by an immunohistochemical technique in a series of 79 patients with surgical stage I-III primary endometrial carcinoma.

RESULTS

Of 79 tissue specimens, 48 (61%) showed a positive reaction for cathepsin D. A significant correlation between cathepsin D and histological grade was found (P < 0.05). The other established clinicopathological prognostic factors were not associated with cathepsin D. There was not any significant difference in prognosis between the positive cases and negative cases for cathepsin D (P > 0.05). In the univariate analysis cathepsin D immunoreactivity did not show significant prognostic value for overall survival (P > 0.05). The multivariate analysis also showed that cathepsin D was not related to patient outcome (P = 0.24, relative risk = 0.34, 95% confidence interval = 0.05-2.09).

CONCLUSIONS

Our results suggest that cathepsin D immunoreactivity may not be of prognostic value but more studies are needed to evaluate the relationship between its immunoreactivity in tumor cells and in other cells.

Gene expression patterns of breast carcinomas distinguish tumor subclasses with clinical implications

The purpose of this study was to classify breast carcinomas based on variations in gene expression patterns derived from cDNA microarrays and to correlate tumor characteristics to clinical outcome. A total of 85 cDNA microarray experiments representing 78 cancers, three fibroadenomas, and four normal breast tissues were analyzed by hierarchical clustering. As reported previously, the cancers could be classified into a basal epithelial-like group, an ERBB2-overexpressing group and a normal breast-like group based on variations in gene expression. A novel finding was that the previously characterized luminal epithelial/estrogen receptor-positive group could be divided into at least two subgroups, each with a distinctive expression profile. These subtypes proved to be reasonably robust by clustering using two different gene sets: first, a set of 456 cDNA clones previously selected to reflect intrinsic properties of the tumors and, second, a gene set that highly correlated with patient outcome. Survival analyses on a subcohort of patients with locally advanced breast cancer uniformly treated in a prospective study showed significantly different outcomes for the patients belonging to the various groups, including a poor prognosis for the basal-like subtype and a significant difference in outcome for the two estrogen receptor-positive groups.

Identification of an estrogen-inducible phosphatase (PP5) that converts MCF-7 human breast carcinoma cells into an estrogen-independent phenotype when expressed constitutively

The proliferation of many estrogen receptor (ER)-positive breast cancer cells depends on estradiol, and tumors arising from these cells are often responsive initially to treatment with selective ER modulators, which produce an antiestrogen effect. However, tumors that are refractory to the antiestrogenic effects of selective ER modulators often reemerge, and the prognosis for these patients is poor because of the lack of additional effective therapy. Accordingly, deciphering the cellular events associated with estrogen-dependent growth and the subsequent outgrowth of tumors with an estrogen-independent phenotype is of considerable interest. Here we show that the expression of PP5, an evolutionarily conserved Ser/Thr phosphatase that functions as an inhibitor of glucocorticoid- and p53-induced signaling cascades leading to growth suppression, is responsive to 17beta-estradiol (E(2)) in ER-positive human breast carcinoma cells (MCF-7). Northern analysis revealed that E(2)-induced PP5 expression is blocked by treatment with tamoxifen, and a consensus ER recognition element was identified in the PP5 promoter. The PP5-ER recognition element associates with human ERs and confers E(2)-induced transcriptional activation to reporter plasmids. The specific inhibition of PP5 expression ablates E(2)-mediated proliferation in MCF-7 cells without having an apparent effect on E(2)-induced expression of c-myc or cyclin D1. Thus, although critical for cell growth, PP5 likely acts either downstream or independently of c-Myc and Cyclin D1. To further characterize the role of PP5 in E(2)-regulated growth control, we constructed stable MCF-7 cell lines in which the expression of PP5 was placed under the control of tetracycline-regulated transactivator and operator plasmids. Studies with these cells revealed that the constitutive overexpression of PP5 affords E(2)-dependent MCF-7 cells with the ability to proliferate in E(2)-depleted media. Together, these studies indicate that E(2)-induced PP5 expression functions to enhance E(2)-initiated signaling cascades leading to cell division and that aberrant PP5 expression may contribute to the development of MCF-7 cells with an estrogen-independent phenotype.

Angiogenesis and blood vessel invasion as prognostic indicators for node-negative breast cancer

This study was undertaken to determine the value of angiogenesis and blood vessel invasion (BVI) using both Factor VIII-related antigen and elastica van Gieson staining in predicting 20-year relapse-free survival (RFS) and 20-year overall survival (OS) rates in Japanese patients with node-negative breast cancer. Two hundred and sixty patients were studied. We investigated nine factors, including angiogenesis (average microvessel count (AMC)), BVI, proliferating cell nuclear antigen (PCNA), p53, c-erbB-2, clinical tumor size (T), histological grade, tumor necrosis, and lymphatic vessel invasion (LVI). Twenty-five patients (9.6%) had recurrence and 17 patients (6.5%) died of breast cancer. Univariate analysis showed that BVI, AMC, T, histological grade, PCNA, p53, and tumor necrosis were significantly predictive of RFS or OS. Multivariate analysis showed that AMC, BVI, and T were significant independent factors for RFS or OS. Moreover, the combination of AMC/BVI was an especially significant factor for RFS or OS (P < 0.0001, P = 0.0003, respectively). When stratified by T, a significant impact of AMC or BVI on RFS was seen in patients with T1, T2, and T3 carcinomas. Multivariate analysis in patients with T2 carcinoma showed that both AMC and BVI were significant independent factors for RFS (P = 0.0231, P = 0.0388, respectively) and OS (P = 0.0331 and P = 0.0479, respectively). AMC, BVI, and T were independent prognostic indicators. As the combined impact of AMC/BVI is especially strong, AMC/BVI is useful in selecting high-risk node-negative breast cancer patients who may be eligible to receive aggressive adjuvant chemotherapy.

Estrogen regulated proteases and antiproteases in ovarian and breast cancer cells

Cathepsin D (cath-D), an estrogen-regulated protease appears mostly to increase the number of tumor cells rather than their invasion or motility through the extracellular matrix. Estradiol is mitogenic but in vitro it also inhibits invasion and motility. In this review, we discuss the mechanism of this inhibition and the hormonal regulation of other proteases and protease inhibitors possibly involved in the control of tumor cell invasion by estrogens.

Co-expression of thymidine kinase and cathepsin D in 200 primary breast carcinomas

We assayed thymidine kinase (TK) and cathepsin D (Cath-D) in 200 breast carcinomas and we found that they were significantly correlated. This correlation was present in lymph node positive tumours, in G2 and G3, in T1 and in invasive ductal carcinomas. In addition, TK and Cath-D did not correlate with oestrogen receptor (ER) and progesterone receptor (PgR) status. We conclude that the relationship between Cath-D and TK may indicate a tumour population of high proliferation activity and invasiveness potential, related to a more aggressive phenotype, whose identification may be useful in defining prognosis.

Systemic enzyme therapy in oncology: effect and mode of action

Plant extracts with a high content of proteolytic enzymes have been used for a long time in traditional medicine. Besides proteolytic enzymes from plants, 'modern' enzyme therapy additionally includes pancreatic enzymes. The therapeutic use of proteolytic enzymes is partly based on scientific studies and is partly empirical. The aim of the current review is to provide an overview of clinical trials of systemic enzyme therapy in oncology, and to discuss the evidence for their possible mechanisms of action. Clinical studies of the use of proteolytic enzymes in oncology have mostly been carried out on an enzyme preparation consisting of a combination of papain, trypsin and chymotrypsin. This review of these studies showed that enzyme therapy can reduce the adverse effects caused by radiotherapy and chemotherapy. There is also evidence that, in some types of tumours, survival may be prolonged. The beneficial effect of systemic enzyme therapy seems to be based on its anti-inflammatory potential. However, the precise mechanism of action of systemic enzyme therapy remains unsolved. The ratio of proteinases to antiproteinases, which is increasingly being used as a prognostic marker in oncology, appears to be influenced by the oral administration of proteolytic enzymes, probably via an induction of the synthesis of antiproteinases. Furthermore, there are numerous alterations of cytokine composition during therapy with orally administered enzymes, which might be an indication of the efficacy of enzyme therapy. Effects on adhesion molecules and on antioxidative metabolism are also reviewed.

Analysis of cathepsin D in human breast cancer: usefulness of the processed 31 kDa active form of the enzyme as a prognostic indicator in node-negative and node-positive patients

The relative amounts of the precursor (52 kDa) and processed (31,27 kDa) forms of cathepsin D have been analyzed by Western blotting in biopsied breast tissue cytosols from 134 lesions from invasive breast cancer patients, 24 lesions from patients with ductal carcinoma in situ (DCIS), 227 lesions from benign breast disease patients, and 28 lesions from normal control subjects. The mean relative percentage amount of the 31 kDa form was significantly increased (p < 0.001) in the invasive breast cancer group compared to the other three groups. In addition, the mean relative percentage amount of the 31 kDa form was significantly increased (p < 0.05) in node-positive compared to node-negative breast cancer patients. In the benign breast disease group, patients with proliferative-type disease had a significantly increased (p = 0.02) mean relative percentage amount of the 31 kDa form of cathepsin D compared to patients with nonproliferative-type disease. Invasive breast cancer patients were followed for up to 75 months to determine if the relative percentage amount of the 31 kDa form of cathepsin D was predictive of disease-free and overall survival. Although the amount of the 31 kDa form was not predictive of disease-free survival, patients in the 'high' 31 kDa group (> 18%) were significantly (p < 0.05) more likely to die than patients in the 'low' 31 kDa group (< or = 18%). The 12 patients who died were all node-positive and in the high 31 kDa group. It thus appears that the relative amount of the processed, active 31 kDa form of cathepsin D is a useful prognostic indicator, at least in node-positive breast cancer patients.

Cathepsin D in breast cancer: mechanisms and clinical applications, a 1999 overview

A short review of the literature first confirms the clinical value of cathepsin D as a prognostic marker in breast cancer, when using well standardized assays. We then summarize results of studies, mostly performed in our laboratory, aimed at understanding the effect of cathepsin D overexpression on metastasis and the molecular mechanisms involved. Cathepsin D-cDNA transfection increases tumor cell proliferation in vitro and the metastatic potential of 3Y1-Ad12 embryonic rat tumorigenic cells when injected in vivo into nude mice. The mechanism by which cathepsin D increases the incidence of clinical metastasis involves increased cell growth and decreased contact inhibition rather than escape of cancer cells through the basement membrane. Different mechanisms are considered to explain this mitogenic activity. Cathepsin D could act as a protease following its activation at an acidic pH, or as a ligand of different membrane receptors at a more neutral pH. In this case cathepsin D can displace IGFII from the mannose-6-phosphate/IGFII receptor to the IGFI receptor or activate another membrane receptor to be identified. The nature of the mechanisms involved in vivo may depend on the micro environment of the tumor cells. These studies should guide in the development of new therapies aimed at inhibiting the deleterious effect of overexpressed cathepsin D.

Bcar1/p130Cas protein and primary breast cancer: prognosis and response to tamoxifen treatment

BACKGROUND

The product of the Bcar1/p130Cas (breast cancer resistance/p130Crk-associated substrate) gene causes resistance to antiestrogen drugs in human breast cancer cells in vitro. To investigate its role in clinical breast cancer, we determined the levels of Bcar1/p130Cas protein in a large series of primary breast carcinomas.

METHODS

We measured Bcar1/p130Cas protein in cytosol extracts from 937 primary breast carcinomas by western blot analysis. The levels of Bcar1/p130Cas protein were tested for associations and trends against clinicopathologic and patient characteristics, the lengths of relapse-free survival and overall survival (n = 775), and the efficacy of first-line treatment with tamoxifen for recurrent or metastatic disease (n = 268).

RESULTS

Bcar1/p130Cas levels in primary tumors were associated with age/menopausal status and the levels of estrogen receptor and progesterone receptor. In univariate survival analysis, higher Bcar1/p130Cas levels were associated with poor relapse-free survival and overall survival (both two-sided P =.04; log-rank test for trend). In multivariate analysis, a high level of Bcar1/p130Cas was independently associated with poor relapse-free survival and overall survival. The response to tamoxifen therapy in patients with recurrent disease was reduced in patients with primary tumors that expressed high levels of Bcar1/p130Cas. In multivariate analysis for response, Bcar1/p130Cas was independent of classical predictive factors, such as estrogen receptor status, age/menopausal status, disease-free interval, and dominant site of relapse.

CONCLUSION

Patients with primary breast tumors expressing a high level of Bcar1/p130Cas protein appear to experience more rapid disease recurrence and have a greater risk of (intrinsic) resistance to tamoxifen therapy. Thus, measurement of Bcar1/p130Cas may provide useful prognostic information for patients with primary or metastatic breast cancer.

Inhibition of cathepsin D by tripeptides containing statine analogs

Various analogs of statine, a remarkable amino acid component of the protease inhibitor pepstatine, were synthesized and evaluated as tripeptide derivatives for their activity against cathepsin D and HIV-1 protease.

Breast-conserving therapy: proteases as risk factors in relation to survival after local relapse

PURPOSE

To evaluate whether cathepsin D, urokinase-type plasminogen activator (uPA), its inhibitor, plasminogen activator inhibitor-1 (PAI-1), or clinical factors can predict which patients are at risk for developing distant metastases after local recurrence (LR).

PATIENTS AND METHODS

Of 1,630 patients treated with breast-conserving surgery and radiotherapy of the breast between 1980 and 1992, LR developed in 171 as a first event. From the available primary tumor tissues, we determined the cytosolic levels of cathepsin D, uPA and PAI-1.

RESULTS

In patients with LR, a short (< or = 2 years) disease-free interval (DFI) and skin involvement of LR were associated with poor postrelapse distant metastasis-free survival (PR-DMFS, P = .001, both) and postrelapse overall survival (PR-OS; P < .0001 and P < .0002, respectively). The primary tumor levels of uPA and PAI-1 were elevated for patients with a short DFI (P < .01), but such a relation was not observed for patients with skin involvement. In univariate analyses, high levels of uPA and PAI-1 in the primary tumor were associated with poor PR-OS (P = .038 and P = .040, respectively) but not PR-DMFS. In Cox multivariate analyses for PR-DMFS and PR-OS, only a short DFI and skin involvement of the LR were independently associated with a poor clinical outcome.

CONCLUSION

In patients treated with breast-conserving therapy who had LR as a first event, a short DFI and skin involvement were strong indicators for poor PR-DMFS and PR-OS. The proteases studied did not contribute significantly to the final multivariate model.

Cathepsin D in cancer metastasis: a protease and a ligand

Cathepsin D (cath-D) overexpression in breast cancer cells is associated with increased risk of metastasis in patients according to several clinical studies. No alterations of pro-cath-D structure or activation have been demonstrated in cancer cells. However, overexpression and dysrouting of pro-cath-D in illegitimate compartments could have consequences on tumor progression. Transfection of a human cDNA cath-D expression vector increases the metastatic potential of 3Y1-Ad12 embryonic rat tumorigenic cells when intravenously injected into nude mice. The mechanism by which cath-D increases the incidence of clinical metastasis seems to involve increased cell growth and decreased contact inhibition rather than escape of cancer cells through the basement membrane. Different mechanisms are discussed by which cath-D could act as a protease following its activation or as a ligand of different membrane receptors at a more neutral pH.