Prognostic value of Cathepsin D expression in breast cancer: immunohistochemical assessment and correlation with radiometric assay

Expression of Cathepsin D in early-stage breast cancer and its prognostic and predictive value

PURPOSE

Cathepsin D is a proteolytic enzyme that is normally localized in the lysosomes and is involved in the malignant progression of breast cancer. There are conflicting results regarding Cathepsin D significance as prognostic and predictor marker in breast cancer. This study aimed to evaluate the expression and prognostic significance of Cathepsin D in early-stage breast cancer.

METHODS

Expression of Cathepsin D was assessed by immunohistochemical staining of tissue microarrays, in a large well-characterized series of early-stage operable breast cancer (n = 954) from Nottingham Primary Breast Carcinoma Series between the period of 1988 and 1998 who underwent primary surgery. Correlation of Cathepsin D expression with clinicopathological parameters and prognosis was evaluated.

RESULTS

Cathepsin D expression was positive in 71.2% (679/954) of breast cancer tumours. Positive expression of Cathepsin D was significantly associated with high histological grade (p = 0.007), pleomorphism (p = 0.002), poor Nottingham Prognostic Index (NPI) score (p < 0.002), recurrence (p = 0.005) and distant metastasis (p < 0.0001). Kaplan-Meier analysis showed that Cathepsin D expression was significantly associated with shorter breast cancer-specific survival (p = 0.001), higher risk of recurrence (p = 0.001) and distant metastasis (p < 0.0001). ER-positive tumours expressing Cathepsin D and treated with tamoxifen demonstrated a significantly higher risk of distant metastasis.

CONCLUSION

Cathepsin D expression significantly predicts poor prognosis in breast cancer and is associated with variables of poor prognosis and shorter outcome. The strong association of Cathepsin D with aggressive tumour characteristics and poor outcomes warrants further research of its potential as a therapeutic target The results also suggest a possible interaction between Cathepsin D and tamoxifen therapy in ER-positive breast cancer which needs further investigation to elucidate the underlying mechanisms.

Cathepsin D versus Other Prognostic Factors in Breast Cancer. Results and Controversies of a Multicenter Study on 2575 Cases

The aim of this study was the survey of cathepsin D determination in a large group of patients enrolled at several centers, under the coordination of the Italian Committee for Quality Control in the Oncological Laboratory. Cathepsin D was measured with the same method-ology, under control of an intra and interlaboratory quality control program, in order to verify the comparability of cathepsin D results from different institutions and to analyze the frequency of cathepsin D positive cases in subgroups of patients stratified according to other prognostic parameters. This retrospective study included 2575 patients with primary breast cancer evaluat-ed in 10 institutions. Cytosol from tumor tissue was the substrate for biochemical cathepsin D, estrogen receptor and progesterone receptor determination, with an interlaboratory quality control survey provided by the E.O.R.T.C. Receptor Group and the Italian Committee for Quality Control in the Oncological Laboratory.

The results of the present study can be summarized as follows:

1) Cathepsin D is independent of menopausal status;

2) In spite of standardization of tissue handling and assay methods, different results may be obtained by different institutions. It is therefore essential that each laboratory calculates its own positive/negative cutoff values prior to any routine clinical use of the parameter. This should be a serious consideration when a multicenter study is planned.

The significance of metastasis-related factors cathepsin-D and nm23 in advanced ovarian cancer

BACKGROUND

Different regulators or effectors of the metastatic cascade can be of prognostic and/or predictive significance. Cathepsin-D and nm23 operate at different levels of the metastatic process and have not yet been analyzed in combination in ovarian cancer.

PATIENTS AND METHODS

The prevalence of cathepsin-D and nm23 expression was studied with immunohistochemistry in a cohort of 185 previously untreated cases of FIGO stage III ovarian cancer. Correlations with known prognostic factors were examined, and both uni- and multivariate survival analyses were performed.

RESULTS

Epithelial cell cathepsin-D expression was found in 58% of cases, stromal cell cathepsin-D expression in 20%, and nm23 expression in 72%. Epithelial cell cathepsin-D expression was positively correlated with better differentiation of the tumor tissue (P = 0.034). No correlation was found between epithelial and stromal cell cathepsin-D expression, but a striking degree of positive correlation was demonstrated between epithelial cell cathepsin-D and nm23 expression (P = 0.005). None of the factors studied was of any value in predicting the response to platinum and anthracyclin combination chemotherapy, as assessed by second look laparotomy. In univariate analysis age, FIGO substage, histological type, differentiation grade, ascites, residual disease and epithelial cathepsin-D were associated with corrected survival. Neither stromal cell cathepsin-D, nor nm23 expression were of prognostic significance. However, in multivariate analysis the combination of epithelial and stromal cell cathepsin-D expression (P = 0.030), residual disease (P = 0.002) and differentiation grade (P = 0.007) were the only remaining independent prognostic factors in this patient group.

CONCLUSIONS

Our results support a favourable prognostic significance of cathepsin-D expression in advanced ovarian cancer, but underscore the importance of considering both epithelial and stromal cell expression. We could not confirm the prognostic significance of nm23 expression in the present cohort of advanced ovarian cancer patients.

The relationship between prognostic and predictive factors in the management of breast cancer

The discovery of new prognostic factors proceeds at a much more rapid pace than our knowledge of how to properly utilize this information in the management of patients with breast cancer, especially those with early breast cancer that has not metastasized to regional lymph nodes. Prognostic factors provide information on how the patient is likely to do regardless of treatment. Predictive factors provide information on whether a patient is likely to benefit from therapy. Most factors identified to date provide prognostic information, but relatively few provide information that is truly helpful in making a therapeutic decision in the management of individual patients. In large part this is because there has been insufficient study of the factor, especially prospective evaluations of the factor. Unfortunately this has resulted in the premature use of this information under the general rubric that patients with a poor prognosis deserve more treatment in spite of the fact that there may be no benefit from that therapy in the poor prognostic group.

Immunoradiometric and immunohistochemical analysis of Cathepsin D in ovarian cancer: lack of association with clinical outcome

The aim of this study was to analyse the clinical significance of Cathepsin D (Cath D) content as determined by an immunoradiometric assay in a series of primary untreated ovarian cancers from 162 patients. In addition, immunohistochemical analysis of Cath D was also performed on a subset of 86 tumours. Cath D levels were distributed in an asymmetrical way and were skewed towards the lower values (median value 20.8 pmol mg(-1) protein, range 2.0-99.0 pmol mg(-1) protein). No correlation was found between Cath D levels and clinicopathological parameters. However, the percentage of Cath D positivity was significantly higher in oestrogen receptor-positive (57%) compared with oestrogen receptor-negative (36%) cases (P= 0.01). The percentage of Cath D-positive staining was not significantly different for both epithelial (27%) and stromal components (40%). Immunoradiometrically detected Cath D levels were not different according to Cath D stromal immunostaining (P= 0.18), while higher Cath D levels were measured in Cath D-positive than in Cath D-negative tumour epithelial cells (P = 0.027). Survival analysis was conducted on 161 primary untreated ovarian cancer patients. The 5-year overall survival rate was 57% and 55% in Cath D-positive and Cath D-negative patients respectively (P = 0.69). As far as time to progression was concerned, there was no significant difference in the survival rate of patients with either high or low Cath D content (P = 0.56). Similar results have been obtained in the subset of patients in which Cath D was analysed by immunohistochemistry. In conclusion, Cath D measurement in tumour extracts appears to have a limited usefulness in improving the prognostic characterization of ovarian cancer patients.

Altered expression of the DNA repair protein, N-methylpurine-DNA glycosylase (MPG) in breast cancer

We examined expression of N-methylpurine-DNA glycosylase (MPG), a DNA repair enzyme that removes N-alkylpurine damage, in normal, malignant, and immortalized breast epithelial cells, and breast cancer cell lines (MDA-MB-231, MCF7, T47D). Northern analysis showed increased expression in cancer versus normal breast epithelial cells (2-24-fold). Southern blots revealed no gene amplification or polymorphisms. Immunofluorescence, immunohistochemistry, and Western blot analysis demonstrated increased MPG protein expression in the tumor cells that correlated with elevated glycosylase activity. Since MPG overexpression has been shown to be paradoxically associated with increased susceptibility to DNA damage, up-regulation of this gene may suggest a functional role in breast carcinogenesis.

An immunohistochemical assessment of cathepsin D in gastric carcinoma: its impact on clinical prognosis

BACKGROUND

In the context of tumor-associated proteolysis, the prognostic value of cathepsin D in breast carcinoma has been studied but its role is controversial in relation to gastrointestinal carcinoma. The aim of the current study was to determine whether cathepsin D is a prognostic parameter for gastric carcinoma, and also to consider interaction with the urokinase-plasminogen activator (uPA) system as an established risk factor for tumor-associated proteolysis.

METHODS

In a consecutive prospective series of 203 gastric carcinoma patients, expression of cathepsin D in tumor cells was semiquantitatively analyzed with immunohistochemistry (scored 0-3). Median follow-up time was 31 months (range, 9-56 months). Kaplan-Meier (log rank) and multivariate Cox analyses were used to analyze survival.

RESULTS

Kaplan-Meier analysis (log rank statistics) revealed significant association of increasing cathepsin D detection with poorer disease free survival (P = 0.0042) and poorer overall survival (P = 0.0018) of curatively resected patients. Overall survival of all patients was not significantly correlated. Multivariate analysis of established risk factors for gastric carcinoma, including the uPA system, identified cathepsin D as a new and independent prognostic parameter for disease free survival (P = 0.020; relative risk, 2.98; 95% confidence interval, 1.28-6.91). Plasminogen activator inhibitor type-1 as a representative of the uPA system was confirmed as a strong independent factor for disease free and overall survival. Chi-square analysis showed significant correlation of higher cathepsin D levels with Laurén's diffuse-type carcinomas and strong evidence of uPA receptor in tumor cells. However, a subgroup analysis performed according to Laurén's classification revealed a univariate prognostic impact of cathepsin D on both diffuse and intestinal types without independent value. For patients with high levels of uPA receptor (scores of 2 and 3, n = 132), a highly significant association of increasing evidence of cathepsin D with disease free survival (P < 0.0001) and overall survival (P < 0.0001) was observed for curatively resected patients. Significant association with survival was also observed for all patients (P = 0.0407).

CONCLUSIONS

Cathepsin D is a new functional prognostic parameter for gastric carcinoma patients with independent value for disease free survival. Moreover, this study indicates that consideration of more than one tumor-associated protease could lead to a more individualized estimation of risk for carcinoma patients.

Cathepsin D detected by automated and quantitative immunohistochemistry in breast carcinomas: correlation with overall and disease free survival

AIM

To determine the prognostic significance and clinical relevance of cathepsin D detected by immunocytochemical assays (ICAs) in breast carcinomas.

METHODS

151 patients presenting with palpable or impalpable breast carcinomas and who had not received any kind of adjuvant chemotherapy or endocrine therapy who were operated from January 1986 to May 1987 were studied. ICAs of tumour specimens were performed in optimal technical conditions (frozen sections, automated immunoperoxidase technique (Ventana), and computer assisted analysis of digitised coloured microscopic images (SAMBA)) to determine cathepsin D immunocytochemical expression. Results of quantitative ICAs were correlated with overall and disease free survival over 8.4 years of follow up in axillary lymph node positive and negative patients.

RESULTS

Cathepsin D immunocytochemical expression in tumours of 15% or more was significantly associated with poor overall survival in the whole group and in node positive patients (Kaplan Meier, log rank test p = 0.003 and p = 0.007); however, it was not correlated with survival in node negative patients. Cathepsin D immunocytochemical expression (> 15%) correlated with short disease free (p = 0.015) and short recurrence free survival (p = 0.021) in the group as a whole but not when node positive and negative patients were evaluated separately.

CONCLUSIONS

In optimal conditions (automated and quantitative ICAs on frozen sections) cathepsin D immunohistochemical expression is a significant prognostic indicator in terms of overall, disease free, and recurrence free survival; however, there is no correlation when node negative patients are considered separately.

Lack of prognostic value of cathepsin D levels for predicting short term outcomes of breast cancer patients

The value of cathepsin D determinations done on tumor cytosols in evaluating the prognosis of breast cancer patients has been debated in the literature. Our previous work suggested that cathepsin D determinations were not of prognostic value, but in that study we used immunoblotting and immunohistochemical methods rather than the more widely used double antibody immunoradiometric (IRMA) assay for measuring cathepsin levels. Here we report our results determining cathepsin D using components of a commercially available IRMA system on a large patient sample (n = 1984). Reagents from a commercially available IRMA kit were used to analyze cathepsin D levels in the cytosols of 1984 patients with breast cancer. All patients had invasive breast cancer with known tumor size and with some axillary nodes pathologically examined. Only patients with T1 and T2 tumor sizes were included. Median follow-up was 37 months. The hypothesis that high cathepsin D levels correlated with poorer outcome (poorer DFS or OS) was not confirmed, either in all patients, or in node-positive or node-negative subsets. Only in patients treated with adjuvant therapy were higher cathepsin D levels correlated with negative outcome (worsened OS, but not DFS), although given the large number of subsets analyzed this correlation may be spurious. Multivariate analyses using interaction terms did not support the concept that high cathepsin D levels correlate with resistance to adjuvant therapy. In this study evaluating the value of cathepsin D using components from a kit widely used for measuring cathepsin D levels, we conclude that cathepsin D is of doubtful value in predicting risk of early relapse or death for patients with newly diagnosed invasive breast cancer.

Quantitative analysis of p185(HER-2/neu) protein in breast cancer and its association with other prognostic factors

The total cellular p185(HER-2/neu) protein (p185) content was measured by ELISA in 346 invasive primary breast cancers, and the results were compared with those of estrogen (ER) and progesterone (PR) receptors, pS2 and Cathepsin D (Cat D) content. At a cut-off level of 260 fmol/mg protein, 53 of the 346 tumors (15%) were p185-positive. A significant positive correlation was observed between p185 levels and those of Cat D, and a weaker, though significant, positive correlation with ER, and pS2 levels, but not with those of PR. However, when only the 293 p185-negative tumors were considered, the correlation between p185 and ER improved substantially, and statistical significance was reached for PR. p185-positive tumors exhibited lower ER and PR content and higher Cat D content than p185-negative tumors. The pS2 content, in contrast, did not undergo significant variation. Tumors considered to be p185-positive were significantly more frequently positive for Cat D at the cut-off of 45 pmol/mg protein, and were more frequently negative for ER and/or PR, but only significant at the cut-off of 15 fmol/mg or higher for both steroid receptors. Finally, p185 status was not associated with menopausal status, tumor size, axillary-lymph-node invasiveness or distant metastases. These results suggest that 260 fmol/mg protein as the cut-off for p185 allows the identification of a tumoral sub-population with a more aggresive phenotype.

Relationship between cathepsin-D content and disease-free survival in node-negative breast cancer patients: a meta-analysis

Several reports have evaluated the correlation between cathepsin-D and overall survival or disease-free survival in node-negative breast cancer patients. Because conflicting data have so far been reported, a meta-analysis was conducted to clarify this problem. Eleven studies were included in our meta-analysis (total of 2690 patients). A specific meta-analytical methodology for censored data was used, and disease-free survival was the primary end point. Patients with low cathepsin-D levels had a significantly better disease-free survival than patients with high cathepsin-D values (meta-analytical odds ratio from 0.59 to 0.60 over the interval from 1 to 7 years). A secondary meta-analysis conducted exclusively on the data from eight studies based on cytosol assay gave substantially similar results. One limitation of our study is that the cut-off values to define high and low cathepsin-D concentrations were not identical in the various studies included in our meta-analysis (range from 20 to 78 pmol mg(-1) protein), thus introducing a possible bias in the statistical analysis of the data. However, a simulation based on the well-accepted method of the so-called publication bias showed that more than 100 null studies would be required to lead our results to a statistical level of non-significance. Considering the results of our meta-analysis, we conclude that the data presently available confirm a statistically significant association between high cathepsin-D values and poor disease-free survival in node-negative breast cancer patients.

Cathepsin D in host stromal cells, but not in tumor cells, is associated with aggressive behavior in node-negative breast cancer

One hundred fifty-four axillary lymph node-negative invasive ductal carcinomas of the breast were immunohistochemically evaluated for the expression of cathepsin D. Formalin-fixed paraffin sections of each tumor were stained using a polyclonal antibody raised against recombinant procathepsin D. Cathepsin D content of tumor cells and host histiocytes and fibroblasts within or immediately at the invasive border of tumors were assessed separately and correlated with histomorphology, estrogen-receptor content, and patients' survival data. Positive cathepsin D staining of tumor cells was associated with a lower nuclear grade and well-differentiated histology, whereas moderate to strong staining of host cells correlated with larger tumor size, higher nuclear grade, poorly differentiated histomorphology, and lack of estrogen-receptor (ER) protein. No statistically significant correlation was found between cathepsin D in tumor cells and survival. There was, however, a statistically significant correlation between moderate to strong cathepsin D staining of host cells and shorter disease-free and overall survivals. Expression of cathepsin D by host cells, however, did not have an independent influence on survival. The authors conclude that cathepsin D in stromal cells, but not in tumor cells, is associated with aggressive behavior in node-negative invasive ductal carcinomas of breast. Furthermore, determination of cathepsin D in cytosolic extracts of tumors is of no practical value because it may represent cathepsin D content of tumor cells, intratumoral host cells, or both.

Expression of cathepsin D in transitional cell bladder tumours

Biopsy specimens from 177 bladder tumours were analysed by immunohistochemical methods for the expression of cathepsin D. Strong expression of cathepsin D was detected in transitional carcinoma cells in 40 per cent of cases. Umbrella cells were positive in 29 per cent of cases and a cathepsin D-positive cell zone composed of tissue macrophages was detected at the invasion front in 34 per cent of tumours. Strong expression of cathepsin D was related to muscle invasive growth phase (T > or = 2) (P = 0.019), grade 2-3 histology (P = 0.008), S-phase fraction over 10 per cent (P = 0.032), and overexpression of epidermal growth factor receptor (EGFR) (P < 0.001). Umbrella cells were positive in low-grade (P = 0.03) papillary tumours (P = 0.02) with an S-phase fraction < or = 10 per cent (P = 0.02). Cathepsin D was expressed in macrophage-like cells in the invasion front in tumours which were densely infiltrated by inflammatory cells (P = 0.017) and in tumours overexpressing EGFR (P = 0.017) or p53 protein (P = 0.007). Progression in N- (P = 0.04) and M-categories (P = 0.01) was related to strong expression of cathepsin D in cancer cells and in univariate survival analysis; this was weakly related to poor outcome (P = 0.09). In multivariate analysis, papillary status (P = 0.055) and S-phase fraction (P = 0.079) predicted prognosis in Ta-1 tumours. In T2-4 tumours, T-category (P < 0.001), papillary status (P < 0.001), S-phase fraction (P = 0.028), and the presence of cathepsin D-positive tissue macrophages (P = 0.017) were independent prognostic factors.

Prognostic value of cathepsin D in breast cancer: comparison of immunohistochemical and immunoradiometric detection methods

AIM

To test whether immunoradiometric or immunohistochemical detection of lysosomal protease cathepsin D in breast cancer is more predictive of outcome.

METHODS

Tumour tissues from 270 primary breast cancer patients were evaluated for the expression of cathepsin D using immunohistochemistry (IH; paraffin embedded tissues) and an immunoradiometric assay (IRMA; cytosol from frozen tissues). Immunohistochemical scores were based on immunoreaction in tumour cells and tumour associated macrophages.

RESULTS

IRMA values (cut off 40 fmol/mg cell protein) correlated significantly with IH values. Recorded incidences of positive immunoreaction in tumour cells using two different cut off values were 52% and 35%, respectively. Macrophages stained positive in 31% of tissues. Combined evaluation of tumour cells and macrophages resulted in positivity rates of 59% and 48%, respectively. Node status was the only variable found to correlate with cathepsin D expression. IH results correlated significantly with clinical outcome (median observation time 68 months) in node negative patients (n = 120) but not in node positive patients (n = 145). Cathepsin D positivity as measured by IRMA was not related to clinical outcome in either group. On multivariate analysis in the node negative group, IH detection of cathepsin D appeared to be the only independent factor indicating prognosis. For node positive patients, tumour grade, size, and receptor status were of prognostic relevance.

CONCLUSIONS

Because of the simple methodology and the minimal amount of tissue used for analysis, immunohistochemistry was preferred to immunoradiometry for cathepsin D measurement; it also provided more predictive data with respect to prognosis.