Relationship between Cathepsin-D and Other Prognostic Factors in Human Breast Cancer

A prognostic model for triple-negative breast cancer patients based on node status, cathepsin-D and Ki-67 index

Objective

The aim of this study was to evaluate clinicopathologic factors that could possibly affect the outcome of patients with triple negative breast cancer and subsequently build a prognostic model to predict patients’ outcome.

Methods

We retrospectively analyzed clinicopathologic characteristics and outcome of 504 patients diagnosed with triple-negative invasive ductal breast cancer. 185 patients enrolled between 2000 and 2002 were designated to the training set. The variables that had statistically significant correlation with prognosis were combined to build a model. The prognostic value of the model was further validated in the separate validation set containing 319 patients enrolled between 2003 and 2006.

Results

The median follow-up duration was 66 months. 174 patients experienced recurrence, and 111 patients died. Positivity for ≥4 lymph nodes, Cathepsin-D positivity, and Ki-67 index ≥20% were independent factors for DFS, while the lymph nodes status and Ki-67 index were the prognostic factors for OS. The prognostic model was established based on the sum of all three factors, where positivity for ≥4 lymph nodes, Cathepsin-D and Ki-67 index ≥20% would individually contribute 1 point to the risk score. The patients in the validation set were assigned to a low-risk group (0 and 1 point) and a high-risk group (2 and 3 points). The external validation analysis also demonstrated that our prognostic model provided the independent high predictive accuracy of recurrence.

Conclusion

This model has a considerable clinical value in predicting recurrence, and will help clinicians to design an appropriate level of adjuvant treatment and schedule adequate appointments of surveillance visits.

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.

Modulation of the estrogen-regulated proteins cathepsin D and pS2 by opioid agonists in hormone-sensitive breast cancer cell lines (MCF7 and T47D): evidence for an interaction between the two systems

In many cancer cell lines, including breast, prostate, lung, brain, head and neck, retina, and the gastrointestinal tract, opioids decrease cell proliferation in a dose-dependent and reversible manner. Opioid and/or other neuropeptide receptors mediate this decrease. We report that only the steroid-hormone-sensitive cell lines MCF7 and T47D respond to opioid growth inhibition in a dose-dependent manner. Therefore, an interaction of the opioid and steroid receptor system might exist, as is the case with insulin. To investigate this interaction, we have assayed two estrogen-inducible proteins (pS2 and the lysosomal enzyme cathepsin D) in MCF7 and T47D cells. When cells were grown in the presence of FBS (in which case a minimal quantity of estrogens and/or opioids is provided by the serum), we observed either no effect of etorphine or ethylketocyclazocine (EKC) or an increase of secretion and/or production of pS2 and cathepsin D. However, when cells were cultured in charcoal-stripped serum and in the absence of phenol red, the effect of the two opioids is different: EKC decreased the production and/or secretion of pS2 and cathepsin D, whereas etorphine increased their synthesis and/or secretion. The differential effect of the two general opioids was attributed to their different receptor selectivity. Furthermore, the variations of the ratio of secreted/produced protein and the use of cycloheximide indicate that opioids selectively modify the regulatory pathway of each protein discretely. In conclusion, through the interaction with opioid and perhaps other membrane-receptor sites, opioid agonists modify in a dose-dependent manner the production and the secretion of two estrogen-regulated proteins. Opioids may therefore disturb hormonal signals mediated by the estrogen receptors. Hence, these chemicals may have potential endocrine disrupting activities.