Compartmentalized Expression of Kallikrein 4 (KLK4/hK4) Isoforms in Prostate Cancer: Nuclear, Cytoplasmic and Secreted Forms

Dong, Ying, Bui, Loan Thuy, Odorico, Dimitri M., Tan, Olivia L., Meyers, Stephen A., Samaratunga, Hemamali, Gardiner, Robert A., & Clements, Judith (2005) Compartmentalized Expression of Kallikrein 4 (KLK4/hK4) Isoforms in Prostate Cancer: Nuclear, Cytoplasmic and Secreted Forms. Endocrine-Related Cancer, 12, pp. 875-889.

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The prostate-specific antigen-related serine protease gene, kallikrein 4 (KLK4), is expressed in the prostate and, more importantly, overexpressed in prostate cancer. Several KLK4 mRNA splice variants have been reported, but it is still not clear which of these is most relevant to prostate cancer. Here we report that, in addition to the full-length KLK4 (KLK4-254) transcript, the exon 1 deleted KLK4 transcripts, in particular, the 50-truncated KLK4-205 transcript, is expressed in prostate cancer. Using V5/His6 and green fluorescent protein (GFP) carboxy terminal tagged expression constructs and immunocytochemical approaches, we found that hK4-254 is cytoplasmically localized, while the N-terminal truncated hK4-205 is in the nucleus of transfected PC-3 prostate cancer cells. At the protein level, using anti-hK4 peptide antibodies specific to different regions of hK4-254 (N-terminal and C-terminal), we also demonstrated that endogenous hK4-254 (detected with the N-terminal antibody) is more intensely stained in malignant cells than in benign prostate cells, and is secreted into seminal fluid. In contrast, for the endogenous nuclearlocalized N-terminal truncated hK4-205 form, there was less difference in staining intensity between benign and cancer glands. Thus, KLK4-254/hK4-254 may have utility as an immunohistochemical marker for prostate cancer. Our studies also indicate that the expression levels of the truncated KLK4 transcripts, but not KLK4-254, are regulated by androgens in LNCaP cells. Thus, these data demonstrate that there are two major isoforms of hK4 (KLK4-254/hK4-254 and KLK4-205/hK4-205) expressed in prostate cancer with different regulatory and expression profiles that imply both secreted and novel nuclear roles.

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ID Code: 10655
Item Type: Journal Article
Refereed: Yes
Additional Information: Articles free to read on journal website after 12 months
Keywords: Kallikrein, Nuclear, Prostate Cancer, Secreded
DOI: 10.1677/erc.1.01062
ISSN: 1351-0088
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2005 Society for Endocrinology
Deposited On: 09 Nov 2007 00:00
Last Modified: 13 Feb 2015 05:09

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