Clathrin pit-mediated endocytosis of neutrophil elastase and cathepsin G by cancer cells

Alyssa D. Gregory, Pamela Hales, David H. Perlmutter, A. Mc Garry Houghton

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


Neutrophil elastase (NE) is a neutrophil-derived serine proteinase with broad substrate specificity. We have recently demonstrated that NE is capable of entering tumor cell endosomes and processing novel intracellular substrates. In the current study, we sought to determine the mechanism by which NE enters tumor cells. Our results show that NE enters into early endosomal antigen-1 + endosomes in a dynamin- and clathrin-dependent but flotillin-1- and caveolin-1-independent fashion. Cathepsin G (but not proteinase-3) also enters tumor endosomes via the same mechanism. We utilized 125I-labeled NE to demonstrate that NE binds to the surface of cancer cells. Incubation of radiolabeled NE with lung cancer cells displays a dissociation constant (K d) of 284 nM. Because NE is known to bind to heparan sulfate- and chondroitin sulfate-containing proteoglycans, we treated cells with glycanases to remove these confounding factors, which did not significantly diminish cell surface binding or endosomal entry. Thus, NE and CG bind to the surface of cancer cells, presumably to a cell surface receptor, and subsequently undergo clathrin pit-mediated endocytosis.

Original languageEnglish
Pages (from-to)35341-35350
Number of pages10
JournalJournal of Biological Chemistry
Issue number42
StatePublished - Oct 12 2012


Dive into the research topics of 'Clathrin pit-mediated endocytosis of neutrophil elastase and cathepsin G by cancer cells'. Together they form a unique fingerprint.

Cite this