DIFFERENT FORMS OF PROSTATE-SPECIFIC ANTIGEN IN CANCER

前列腺癌是美国男性的主要癌症形式。 前列 血清特异性抗原（PSA）水平为前列腺增生提供了良好的标志物。 但单独测定血清总PSA不能区分早期 前列腺癌与其他前列腺疾病的关系 大量的侵入性和 诊断可能需要昂贵的程序。 初步结果 的申请人指出PSA以不同形式存在于精液中， 在不同的人血清中发现不同的PSA形式， 患者 该提案要求提供资金，以建立一个新的独立的 申请人的研究领域，其中各种形式的PSA将 在大量的边缘性疾病患者中进行鉴定， 总PSA升高，并与诊断相关。 长期 目的是为临床提供生物化学和免疫化学依据， 区分早期前列腺癌与其他前列腺癌的PSA形式的测定 导致PSA适度升高的情况。 假设：a） PSA作为一种酶，在前列腺癌中的作用可能与前列腺癌不同。 前列腺或前列腺炎的良性病症; B）PSA酶 以无活性酶原形式分泌，在特定条件下活化， 病理生理条件下，并通过蛋白水解裂解或 通过与可用的蛋白酶抑制剂组合以形成复合物; c） 局部环境和分泌这种物质的上皮细胞的类型 前列腺癌与其他综合征相比PSA不同; d） PSA暴露的活化剂、蛋白水解酶和抑制剂 与其他综合征相比，癌症的不同; e）经过的时间 PSA的分泌与其向血液的转运之间的差异， 癌症与其他综合征; f）酶谱和 前列腺液中的抑制剂不同于血液中的抑制剂;以及g） 所有这些都导致了不同形式的PSA的产生， 前列腺癌与其他综合征的区别。 申请人的 以前的经验，阐明分子形式和抑制剂， 其它酶可容易地用于鉴定， 测量患者中不同形式的PSA。 具体目标 包括：1）从精液中分离PSA，鉴定其 与各种蛋白酶抑制剂的反应性，以及标准品的制备 PSA-抑制剂复合物; 2）PSA的夹心ELISA测定法的开发 与任何重要抑制剂的复合物，包括 α 1-抗胰凝乳蛋白酶，蛋白C抑制剂，α 2-巨球蛋白，和 其他可以识别的，使用标准复合物; 3） 用免疫组织化学法鉴定精液和血液中不同形式的PSA 免疫印迹分析和测序研究; 4）抗体的开发 和特异于PSA的特定形式或序列的ELISA测定; 5） 免疫印迹分析、夹心ELISA和其他测定的应用 其发展为大量患者血清，特别是那些在 PSA的临界范围;以及6）光谱和水平的相关性 不同的PSA形式对患者的诊断，以建立临床 分析的有用性。 这些研究还提供了新的基础。 关于PSA及其抑制剂的知识，可能有助于了解 该酶的生理功能和调节。

Prostate cancer is a major form of cancer in U.S. males. Prostate specific antigen (PSA) serum levels provide a good marker for prostate cancer, but assay of total serum PSA alone cannot distinguish early cancer from a number of other prostatic diseases. Numerous invasive and expensive procedures may be required for diagnosis. Preliminary results of the applicant indicate that PSA exists in different forms in semen and in serum and that different PSA forms are found in the sera of different patients. This proposal requests funding to establish a new independent research area for the applicant, in which the various forms of PSA will be identified, assayed in a large number of patients with borderline elevations of total PSA, and correlated to the diagnosis. The long-term goal is to provide the biochemical and immunochemical basis for clinical assays of forms of PSA that distinguish early prostate cancer from other conditions that cause modestly elevated PSA. It is hypothesized: a) that PSA as an enzyme may have a different role in prostate cancer than in benign conditions of the prostate or prostatitis; b) that the enzyme PSA is secreted in inactive zymogen form, activated under particular pathophysiological conditions, and inactivated by proteolytic cleavage or by combining with available protease inhibitors to form complexes; c) that the local environment and the type of epithelial cells that secrete PSA differ in prostate cancer compared to other syndromes; d) that the activators, proteolytic enzymes and inhibitors to which PSA is exposed differ in cancer compared to other syndromes; e) that the time elapsed between secretion of PSA and its translocation to the blood differs in cancer versus other syndromes; f) that the spectrum of enzymes and inhibitors in prostatic fluid is different from that of blood; and g) that all of the above lead to the generation of different forms of PSA in prostate cancer from those found in other syndromes. The applicant's previous experience in elucidating the molecular forms and inhibitors of other enzymes can be readily applied to the identification and measurement of different forms of PSA in patients. The specific aims include: 1) isolation of PSA from semen, characterization of its reactivity with various protease inhibitors, and preparation of standard PSA-inhibitor complexes; 2) development of sandwich ELISA assays for PSA complexes with any significant inhibitors, including alpha1-antichymotrypsin, protein C inhibitor, alpha2-macroglobulin, and others that may be identified, using standard complexes; 3) identification of different forms of PSA in semen and in blood by immunoblot analysis and sequencing studies; 4) development of antibodies and ELISA-assays specific for particular forms or sequences of PSA; 5) application of immunoblot analysis, sandwich ELISAS and other assays which are developed to large numbers of patient sera, especially those in the borderline PSA range; and 6) correlation of the spectrum and levels of different PSA forms to patient diagnosis to establish clinical usefulness of the assays. The proposed studies also provide novel basic knowledge about PSA and its inhibitors that may help to understand the physiological function and regulation of this enzyme.