Marco Bisoffi, PhD Department of Biochemistry and Molecular Biology University of New Mexico, School of Medicine Albuquerque, NM 87131 University of New Mexico mbisoffi@salud.unm.edu Phone:(505) 272-8157

Title: Markers of Prostate Cancer Progression: A Telomere-Based Proteomic Approach

Project Description:

The Problem: Prostate cancer (PCa) is the most commonly diagnosed malignancy in American men aged >50 years. The American Cancer Society estimated that in 2003, 220,900 men were diagnosed with PCa and 28,900 died of the disease. The morbidity and mortality of PCa patients is strongly associated with disease recurrence due to the metastatic spread of malignant prostate epithelial cells. However, only approximately 10% of men with clinically detected PCa will die from their disease, reflecting the overall indolent nature of prostatic adenocarcinoma. Nevertheless, the advent of screening modalities for PCa, particularly the prostate-specific antigen (PSA) test, has greatly increased the number of men diagnosed with PCa. The therapeutic choices for most men with clinically localized disease are usually radical prostatectomy (RP) and radiation therapy (RT). The consequences and complications of these treatments are frequently severe, including incontinence, urethral stricture, impotence and death. Because management with "watchful waiting" is controversial, and because current markers often lack the sensitivity and specificity to reliably predict the course of disease, many men diagnosed with PCa undergo unnecessary aggressive therapies, whose serious complications markedly reduce the quality of life. Thus, there is a need for additional and reliable prognostic markers able to discriminate the minority of men that are at high-risk and will benefit from aggressive therapies from the majority of men that are at low risk and can be spared aggressive treatment without curative benefit.

Preliminary Data, Hypothesis and Specific Aims: Our studies on telomeres in archival PCa specimens show that a reduced content of telomeric DNA (TC) is an independent predictor of disease-free survival. Intriguingly, low TC in histologically "normal" prostate tissue coexisting with the tumor is also associated with disease-free survival, implying that telomere attrition is an early event in the course of cancer progression. Short telomeres are a prime source of genomic instability, and as a consequence, a driver of phenotypic variability. Thus, we hypothesize that prostate epithelial cells of tumors with reduced TC express phenotypes of disease recurrence, such as invasion, extravasation, and metastasis. Accordingly, we predict that their protein expression profiles can reveal predictors of cancer progression. This is in agreement with Bernards' and Weinberg's recent provocative statement that invasive traits may be acquired early in cells that "start off on the wrong foot". We propose a proteomic approach to identify such markers in both, cell models of PCa progression, and in fresh prostatectomy specimens with low TC.

Specific Aims:
Aim 1: Identify proteins that are differentially expressed in either (i) the cells of the LNCaP/C4-2/C4-2B human cell model of PCa progression, (ii) in epithelial cells isolated from prostate tumors with high or low TC, or (iii) in both sources.
Aim 2: Confirm differential expression by Western blot (WB) and reverse transcriptase-polymerase chain reaction (RT-PCR).

Relevance and Innovation: The proposed research has translational potential: It addresses an important problem in the clinical management of PCa treatment, in that it aims to identify much needed predictors of disease recurrence. Also, these markers could represent new therapeutic targets. The innovation of the proposed research relies (i) on its novel approach to marker discovery that includes the "telomeric parameter" of prostate tumors leading to the discrimination between markers of progression vs. cell transformation; and (ii) on its use of proteomic technologies that directly address functional aspects of PCa progression.