PROSTATE TUMOR DIAGNOSIS: BLOOD CELL MULTIGENE SIGNATURES

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。目前的前列腺癌筛查和风险评估技术，作为外科活检程序的先决条件，是基于个体血清生物标志物的测量，或循环恶性细胞中个体基因的表达。这些技术有一些局限性，包括在诊断中缺乏特异性和准确性，也缺乏预后信息。这最终会产生大量的假阳性诊断，从而导致不必要的大量手术活检。越来越多的证据表明，患有前列腺癌和其他形式恶性疾病的个体表现出的免疫反应可以在外周血循环中白细胞基因表达改变的水平上检测到。白细胞中多个基因mRNA转录物的定量研究表明，基因表达水平与肿瘤的存在之间存在关联。已有研究表明，血清中单个蛋白的水平与白细胞中差异基因表达有一定程度的相关性，并提供了肿瘤分期的一些信息。此外，我们已经启动了一项试点研究，以检查患有前列腺癌的非裔美国男性的基因表达水平，并显示了多个基因的表达差异，与多个基因的健康对照相比。假设：这些观察结果构成了本研究的假设和实验设计的基础。微阵列技术的使用将使我们能够同时测量来自前列腺癌患者和对照个体血液的循环白细胞中多达14,000个转录基因的表达水平。通过这项技术，我们建议研究前列腺癌患者外周血白细胞中基因表达水平的保守模式或特征，这与对照组白细胞的相应表达模式不同。我们将进一步验证一个假设，即不同组织学级别的前列腺肿瘤患者将产生不同的表达特征，反映肿瘤的生物学分期和侵袭性，从而可以用于区分不同病理阶段的肿瘤。本项目的具体目标是：具体目标一：a)在本项目为期两年的时间里，收集40名前列腺癌患者和20名健康对照者的血液白细胞。b)采用Affymetrix基因芯片微阵列技术测量白细胞样本中的全局基因表达。c)利用数据分析算法建立能够区分前列腺癌患者和对照组的白细胞多基因表达特征。特异性目标2：利用特异性目标1下产生的表达数据，将前列腺癌患者根据前列腺肿瘤进展的特定阶段进行分组。本提案的最终目标。本研究的最终目标是开发一种不需要侵入性手术的新技术，既能提供前列腺癌的准确诊断，又能提供肿瘤分期和生物侵袭性的详细预后信息。该项目的成功将为前列腺癌的分期诊断提供一种急需的非侵入性工具，从而作为识别前列腺肿瘤患者的重要预筛查。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Current techniques for the screening and risk assessment of prostate cancer, as a prerequisite to surgical biopsy procedures, are based upon the measurement of either individual serum biomarkers, or expression of individual genes in circulating malignant cells. These techniques possess a number of limitations, including lack of specificity and accuracy in the diagnosis and, also a lack of prognostic information. This ultimately yields high numbers of false positive diagnoses, and consequently unnecessarily large numbers of surgical biopsies. There is growing evidence that individuals with prostate cancer and other forms of malignant disease, exhibit immune responses that can be detected at the level of altered gene expression in leukocytes circulating in peripheral blood. Quantitation of the mRNA transcripts in leukocytes of a number of individual genes has demonstrated associations between gene expression levels and the presence of a tumor. It has been shown that serum levels of individual proteins exhibit a degree of correlation with differential gene expression in leukocytes, and provides some information on tumor stage. Additionally, we have initiated a pilot study to examine gene expression levels in African-American men with prostate cancer, and have shown expression difference for multiple genes, compared to healthy controls of multiple genes. Hypothesis: These observations form the basis of the hypothesis and experimental design of this proposed study. The use of microarray technology will allow us to measure simultaneously the expression levels of up to 14,000 genes transcribed in circulating leukocytes derived from the blood of prostate cancer patients and control individuals. With this technology, we propose to investigate the hypothesis that individuals suffering from prostate cancer exhibit a conserved pattern, or signature, of gene expression levels in their peripheral blood leukocytes, which is distinct from the corresponding pattern of expression in leukocytes from control subjects. We will test the further hypothesis that cancer patients with prostate tumors at different histological grades, will yield distinct expression signatures that reflect the biological stage and aggressiveness of the tumor, and that can thus be employed to differentiate among tumors at different pathological stages. The Specific aims of this entire proposal are to: Specific Aim One: a) Collect Blood Leukocytes from 40 Prostate Cancer Patients and 20 Healthy Control Subjects Over the Two Year Period of This Project. b) Employ Affymetrix GeneChip Microarray Technology to Measure Global Gene Expression in the Leukocyte Samples. c) Employ Data Analysis Algorithms to Establish Leukocyte Multigene Expression Signatures that Can Distinguish Between Prostate Cancer Patients and Control Subjects. Specific Aim Two: Utilize the Expression Data Generated Under Specific Aim One, to Permit Classification of Prostate Cancer Patients into Groups Corresponding to Specific Stages of Prostate Tumor Progression. Ultimate Goal of this Proposal. The ultimate goal of the research proposed here is to develop a novel technique that does not require invasive surgery, yet provides an accurate diagnosis of prostate cancer, and also provides detailed prognostic information on the stage and biological aggressiveness of the tumor. The success of this project would yield a much needed, non-invasive tool for stage-specific diagnosis of prostate cancer of the disease, and thus serve as an important pre-screen to identify men with prostate tumors.