This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sato, M. Articles by Wu, L. Search for Related Content PubMed PubMed Citation Articles by Sato, M. Articles by Wu, L.

Functionality of Androgen Receptor–Based Gene Expression Imaging in Hormone Refractory Prostate Cancer

Authors' Affiliations: Departments of ¹ Urology, ² Molecular Cellular and Integrative Physiology, ³ Biological Chemistry, and ⁴ Molecular and Medical Pharmacology; ⁵ Crump Institute for Molecular Imaging; and ⁶ Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; and ⁷ Department of Radiology and the Bio-X Program, Stanford University, Stanford, California

Requests for reprints: Lily Wu, Department of Urology, University of California, Los Angeles, 675 Charles Young Drive South, Los Angeles, CA 90095-1738. Phone: 310-794-4390; Fax: 310-825-3027; E-mail: lwu{at}mednet.ucla.edu.

Purpose: A highly augmented, prostate-specific two-step transcriptional amplification (TSTA) method was developed with the ultimate goal of delivering an effective and safe gene-based treatment to prostate cancer patients. Because very limited treatment options are available for recurrent hormone refractory prostate cancer (HRPC), it is imperative to assess whether the prostate-specific antigen (PSA) promoter-based TSTA gene therapy will be functional in HRPC.

Experimental Design: We tested the TSTA-driven adenovirus vector on three androgen-dependent and six HRPC models. Real-time gene expression was monitored by both optical imaging and the combined modality of positron emission tomography (PET) and computed tomography.

Results: The TSTA-driven firefly luciferase expressing adenoviral vector was active in all androgen receptor (AR)–expressing HRPC models, but inactive in AR- and PSA-negative lines. Interestingly, the TSTA-mediated gene expression was induced by hydrocortisone in MDA PCa 2b, a cell line with mutated AR that possesses altered ligand specificity. In animal models, the TSTA-mediated optical signal was more robust in the HRPC than androgen-dependent tumors. In a parallel trend, a TSTA vector that expresses the herpes simplex virus thymidine kinase PET reporter gene also displayed more robust PET signal in the HRPC tumor.

Conclusions: The activity of TSTA system is AR dependent and it recapitulates the functional status of endogenous AR. These data support the conclusion that AR function is activated in HRPC despite castrated levels of androgen. Together with the fact that majority of recurrent prostate cancers express AR and PSA, we foresee that the TSTA approach can be a promising gene therapy strategy for the advanced stages of prostate cancer.

Key Words: prostate cancer • AR • molecular imaging • prostate-specific promoter • gene therapy

This article has been cited by other articles:

				S. K. Lyons, E. Lim, A. O. Clermont, J. Dusich, L. Zhu, K. D. Campbell, R. J. Coffee, D. S. Grass, J. Hunter, T. Purchio, et al. Noninvasive Bioluminescence Imaging of Normal and Spontaneously Transformed Prostate Tissue in Mice. Cancer Res., May 1, 2006; 66(9): 4701 - 4707. [Abstract] [Full Text] [PDF]

				R. Ilagan, L. J. Zhang, J. Pottratz, K. Le, S. Salas, M. Iyer, L. Wu, S. S. Gambhir, and M. Carey Imaging androgen receptor function during flutamide treatment in the LAPC9 xenograft model Mol. Cancer Ther., November 1, 2005; 4(11): 1662 - 1669. [Abstract] [Full Text] [PDF]