Internalization by multiple endocytic pathways and lysosomal processing impact maspin-based therapeutics

Thomas M. Bodenstine, Richard E.B. Seftor, Elisabeth A. Seftor, Zhila Khalkhali-Ellis, Nicole A. Samii, J. Cesar Monarrez, Grace S. Chandler, Philip A. Pemberton, Mary J.C. Hendrix*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Patients with metastatic disease face high rates of mortality with a paucity of therapeutic options. Protein-based therapeutics provide advantages over traditional chemotherapy through increased specificity, decreased immune impairment, and more direct means of delivery. However, development is often hindered because of insufficient knowledge about protein processing by cells when exogenously applied. This study focuses on recombinant Maspin (rMaspin), a serine protease inhibitor (SERPINB5), which alters invasive properties when directly applied to cancer cells. Previous evidence suggests differences in the effects of rMaspin treatment when compared with endogenous reexpression, with little explanation for these discrepancies. A leading hypothesis is that exogenously applied rMaspin is subject to different regulatory and/or processing mechanisms in cancer cells when compared with endogenous expression. Therefore, a more detailed understanding of the mechanisms of internalization and subcellular trafficking of rMaspin is needed to guide future translational development. We describe the molecular trafficking of rMaspin in cytoplasmic vesicles of the endosomal/lysosomal pathway and characterize its uptake by multiple endocytic mechanisms. Time-lapse laser scanning confocal microscopy shows the uptake, in real time, of dye-labeled rMaspin in cancer cells. This study indicates that cellular processing of rMaspin plays a key role by affecting its biologic activity and highlights the need for new approaches aimed at increasing the availability of rMaspin when used to treat cancer.

Original languageEnglish (US)
Pages (from-to)1480-1491
Number of pages12
JournalMolecular Cancer Research
Volume12
Issue number10
DOIs
StatePublished - Oct 1 2014

ASJC Scopus subject areas

  • Molecular Biology
  • Oncology
  • Cancer Research

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