Cathepsin B

Stains
Cathepsin B (CTSB)

Author: Nat Pernick, M.D. (see Authors page)

Revised: 23 November 2015, last major update September 2012

Copyright: (c) 2003-2015, PathologyOutlines.com, Inc.

PubMed Search: cathepsin b[title]

Table of Contents

Cite this page: Cathepsin B. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/stainscathepsinb.html. Accessed July 12th, 2017.

Definition / general

Lysosomal cysteine protease associated with focal adhesions, inhibited by cystatin C, an endogenous cysteine protease inhibitor
Usually acts only in cell cytoplasm, but in malignant tumors is secreted extracellularly and degrades extracellular matrix so tumor cells can invade
Highest staining at invasive edge of tumor
Acts as effector of invasion in HER2+ breast cancer (Mol Cell 2012;45:764), inflammatory breast cancer (Breast Cancer Res 2011;13:R115), prostate cancer (Int J Cancer 2012;131:2034)
In gliomas, radiation treatment increases cathepsin B levels, suggesting that inhibition may be useful therapy (Neuro Oncol 2012;14:745, Mol Carcinog 2012;52:777)
Inhibition may limit breast cancer metastases (Cancer Res 2012;72:1199)

Clinical features

CSF levels increase with age (Neurol Sci 2012;34:445)
Endosomal cathepsin B may play a functional role in activation of highly pathogenic Nipah virus (J Virol 2012;86:3736)

Uses by pathologists

Cytoplasmic stain, but intense staining may appear nuclear
High expression is poor prognostic marker in colon carcinoma, gliomas (Hum Pathol 2005;36:1008), lung cancer (serum levels, Oncol Lett 2011;2:693)

Microscopic (histologic) images

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