Table of Contents
International Journal of Proteomics
Volume 2012, Article ID 245819, 10 pages
http://dx.doi.org/10.1155/2012/245819
Research Article

Cathepsin D Expression in Colorectal Cancer: From Proteomic Discovery through Validation Using Western Blotting, Immunohistochemistry, and Tissue Microarrays

1Wakefield Biomedical Research Unit, University of Otago, Wellington 6242, New Zealand
2School of Medicine and Health Sciences, University of Otago, Wellington 6242, New Zealand
3Department of Pathology and Molecular Medicine, University of Otago, Wellington 6242, New Zealand
4Capital & Coast District Health Board, Wellington Hospital, Wellington 6021, New Zealand
5Centre for Biodiscovery, School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand

Received 29 February 2012; Revised 19 June 2012; Accepted 24 June 2012

Academic Editor: Fumio Nomura

Copyright © 2012 Chandra Kirana et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Despite recent advances in surgical techniques and therapeutic treatments, survival from colorectal cancer (CRC) remains disappointing with some 40–50% of newly diagnosed patients ultimately dying of metastatic disease. Current staging by light microscopy alone is not sufficiently predictive of prognosis and would benefit from additional support from biomarkers in order to stratify patients appropriately for adjuvant therapy. We have identified that cathepsin D expression was significantly greater in cells from invasive front (IF) area and liver metastasis (LM) than those from main tumour body (MTB). Cathepsin D expression was subsequently examined by immunohistochemistry in tissue microarrays from 119 patients with CRC. Strong expression in tumour cells at the IF did not correlate significantly with any clinico-pathological parameters examined or patient survival. However, cathepsin D expression in cells from the MTB was highly elevated in late stage CRC and showed significant correlation with subsequent distant metastasis and shorter cancer-specific survival. We also found that macrophages surrounding tumour cells stained strongly for cathepsin D but there was no significant correlation found between cathepsin D in macrophages at IF and MTB of CRC patient with the clinic-pathological parameters examined.