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.
Wolf
Marlene
M
Theodor-Kocher Institute, University of Bern, Bern, Switzerland.
Clark-Lewis
Ian
I
Buri
Caroline
C
Langen
Hanno
H
Lis
Maddalena
M
Mazzucchelli
Luca
L
D000595:Amino Acid Sequence; D001943:Breast Neoplasms / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000473:pathology*; D002402:Cathepsin D / Q000235:genetics / Q000378:metabolism*; D054421:Chemokine CCL21; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D019742:Chemokines, CC / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic / Q000276:immunology; D006801:Humans; D007700:Kinetics; D019402:Macrophage Inflammatory Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured
C515478:CCL21 protein, human; D054421:Chemokine CCL21; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D019742:Chemokines, CC; D019402:Macrophage Inflammatory Proteins; D002402:Cathepsin D