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Cathepsin D (CatD), a lysosomal aspartyl protease encoded by the CTSD gene, functions in protein degradation and activation of bioactive precursors through cleavage at acidic pH. Its structure includes a signal peptide, propeptide, and catalytic domain with two aspartic residues essential for enzymatic activity. Estrogen receptor (ER) signaling drives CatD overexpression in hormone-responsive breast cancers via TATA-dependent transcription initiation, mediated by upstream stimulatory factors USF-1/USF-2 binding to E-box elements. In ER-positive tumors, CatD secretion promotes metastasis by degrading extracellular matrix components and enhancing cell motility. Clinically, CatD expression correlates with aggressive breast cancer phenotypes, including high histological grade, and reduced survival.
Therapeutically, CatD serves as a prognostic biomarker for breast cancer stratification and a predictor of tamoxifen resistance. Inhibitors like pepstatin A and small-molecule analogs targeting its active site are under investigation for metastatic breast cancer and AD3. In smokers, monitoring BALF CatD levels (>3,600 U/mL) may identify early lung damage, guiding preventive interventions. These dual roles in proteostasis and disease underscore CatD’s potential as a multifunctional therapeutic node.
Common uses include proteolytic enzyme studies, cancer research.
Not a hazardous substance or mixture.
11 - Combustible Solids
