前列腺特异膜抗原对前列腺疾病的临床诊断意义

目的评价血清中前列腺特异膜抗原（PSMA）浓度对前列腺疾病的辅助诊断意义。方法采用Western印迹分析检测患者血清中PSMA的浓度,前列腺特异抗原（PSA）检测采用通用的免疫化学发光法检测。分析二者在不同分组中的浓度差异及相关性。结果前列腺癌患者的血清中PSMA浓度显著高于正常人群,良性前列腺增生和前列腺炎的患者则低于正常人群,而PSA浓度无论是前列腺癌还是前列腺良性病变均高于正常人。结论前列腺特异膜抗原浓度可以作为区分前列腺癌和良性前列腺增生的辅助诊断标志物。     

Quantitation of serum prostate-specific membrane antigen by a novel protein biochip immunoassay discriminates benign from malignant prostate disease

The lack of a sensitive immunoassay for quantitating serum prostate-specific membrane antigen (PSMA) hinders its clinical utility as a diagnostic/prognostic biomarker. An innovative protein biochip immunoassay was used to quantitate and compare serum PSMA levels in healthy men and patients with either benign or malignant prostate disease. PSMA was captured from serum by anti-PSMA antibody bound to ProteinChip arrays, the captured PSMA detected by surface-enhanced laser desorption/ionization mass spectrometry, and quantitated by comparing the mass signal integrals to a standard curve established using purified recombinant PSMA. The average serum PSMA value for prostate cancer (623.1 ng/ml) was significantly different (P < 0.001) from that for benign prostate hyperplasia (117.1 ng/ml) and the normal groups (age <50, 272.9 ng/ml; age >50, 359.4 ng/ml). These initial results suggest that serum PSMA may be a more effective biomarker than prostate-specific antigen for differentiating benign from malignant prostate disease and warrants additional evaluation of the surface-enhanced laser desorption/ionization PSMA immunoassay to determine its diagnostic utility.     

Preferential association of prostate cancer cells expressing prostate specific membrane antigen to bone marrow matrix

Prostate specific membrane antigen (PSMA) is a transmembrane glycoprotein expressed almost exclusively in prostatic epithelial cells. Expression of PSMA is elevated in prostate cancer, with levels closely correlated with disease grade. Although the highest levels of PSMA expression are associated with high-grade, hormone-refractory and metastatic prostate cancer, the significance of elevated PSMA expression in advanced prostate cancer has yet to be fully elucidated. We provide evidence that prostatic carcinoma cells expressing PSMA exhibit reduced motility and increased attachment when grown on a bone marrow matrix substrate. This phenomenon occurs via activation of focal adhesion kinase and provides the first evidence of a link between PSMA expression and prostate cancer metastasis to the bone.     

Expression of prostate specific membrane antigen and three alternatively spliced variants of PSMA in prostate cancer patients

Prostate specific membrane antigen (PSMA) is a folate gamma glutamyl carboxypeptidase that is oriented on the plasma membrane of normal and prostate cancer cells. A cytosolic version of PSMA, PSM', results from alternative splicing of the PSMA gene. Two additional alternatively spliced variants of PSMA, PSM-C and PSM-D, have been described recently. The ratio of PSMA to PSM' mRNA was higher in a small number of prostate cancer specimens compared to normal prostate cancer and benign prostatic hypertrophy (Su et al. Cancer Res 1995;55:1441). The intent of our study was to measure the gene expression of PSMA and the 3 PSMA splice variants in a large number of patient's tissues. A real-time, quantitative PCR assay was developed to quantify PSMA, PSM', PSM-C and PSM-D. Discrimination among the variants was achieved by designing unique primers and TaqMan probes for each gene. Amplification and detection was specific for the desired splice variant and was sensitive to one gene copy per reaction. The assay was used to quantify the gene expression in specimens of normal, benign, primary and metastatic prostate cancer from 72 patients. The mean PSMA expression (relative to 18S rRNA) was 2- to 3-fold lower in normal prostate (n = 4) compared to primary (n = 55, p = 0.31) and metastatic (n = 20, p = 0.33) prostate cancer. There was no difference in the PSMA expression between benign and cancerous prostate tissue from the same patients (n = 35). The ratio of PSMA to PSM' was lowest in the normal prostate and increased with increasing Gleason score (p < 0.001). The increased ratio in these tissues was a reflection of both increasing PSMA levels and decreasing PSM' mRNA. The expression of PSM-C did not differ in any of the tissue categories studied. The expression of PSM-D was similar in normal and primary prostate cancer but was 2-fold higher in lymph node (p < 0.005) and bone metastases (p < 0.05) compared to the primary tumors. Our results of the first detailed quantitative analysis of PSMA mRNA expression in patient's tissues demonstrate that PSMA and the 3 PSMA splice variants are expressed in normal, benign, cancerous and metastatic prostate cancer. We note increased PSMA expression in some malignant tissues, however, these increases are modest in magnitude. We also report that the expression of a novel splice variant, PSM-D, is elevated in prostate cancer metastases.     

Detection and characterization of the prostate-specific membrane antigen (PSMA) in tissue extracts and body fluids

The prostate-specific membrane antigen (PSMA) glycoprotein is recognized by the monoclonal antibody (MAb) 7EII -C5.3 as a predominant 100 kDa and minor 180 kDa component in LNCaP cell line extracts and its expression has been shown by immunohistochemistry to be highly restricted to prostate epithelium. The aim of the present study was to utilize Western blot analysis to determine if PSMA could be detected in human tissue extracts and body fluids and if so, which molecular forms were present. PSMA was detected as 120 and 200 kDa bands in normal, benign and malignant prostate tissues and seminal plasma. Further analysis demonstrated that the larger molecular form of PSMA may be a dimer of the lower m.w. species. The PSMA glycoprotein was not detected in the majority of non- prostate tissue extracts examined except for a low yet significant amount in normal salivary gland, brain and small intestine, suggesting that PSMA may not be as prostate-specific as originally thought. Since the prostate-specific antigen (PSA) has been shown to be maximally shed into the serum in high-grade and metastatic prostate carcinomas, it was surprising that PSMA could not be detected in serum by Western blot analysis even in patients with actively progressive metastatic disease. Second generation antibodies generated against different epitopes may be required to determine if PSMA is shed into serum. Our results support the hypothesis that PSMA is a novel prostate biomarker. © 1995 Wiley-Liss, Inc.     

A single-chain fragment against prostate specific membrane antigen as a tool to build theranostic reagents for prostate cancer

Prostate carcinoma is the most common non-cutaneous cancer in developed countries and represents the second leading cause of death. Early stage androgen dependent prostate carcinoma responds well to conventional therapies, but relatively few treatment options exist for patients with hormone-refractory prostate cancer. One of the most suitable targets for antibody-mediated approaches is prostate specific membrane antigen (PSMA) which is a well known tumour associated antigen. PSMA is a type II integral cell-surface membrane protein that is not secreted, and its expression density and enzymatic activity are increased progressively in prostate cancer compared to normal prostate epithelium, thereby making PSMA an ideal target for monoclonal antibody imaging and therapy.To obtain a small protein that can better penetrate tissue, we have engineered a single-chain variable fragment (scFv) starting from the variable heavy and light domains of the murine anti-PSMA monoclonal antibody D2B. scFvD2B was analysed in vitro for activity, stability, internalisation ability and in vivo for targeting specificity. Maintenance of function and immunoreactivity as well as extremely high radiolabelling efficiency and radiochemical purity were demonstrated by in vitro assays and under different experimental conditions. Despite its monovalent binding, scFvD2B retained a good strength of binding and was able to internalise around 40% of bound antigen. In vivo we showed its ability to specifically target only PSMA expressing prostate cancer xenografts. Due to these advantageous properties, scFvD2B has the potential to become a good theranostic reagent for early detection and therapy of prostate cancers.     

Effect of exogenous testosterone replacement on prostate-specific antigen and prostate-specific membrane antigen levels in hypogonadal men

Previous studies have suggested that serum prostate-specific antigen (PSA) levels are under androgenic influence, especially in patients with adenocarcinoma of the prostate. PSMA (prostate-specific membrane antigen) is thought to reflect hormonal or clonal resistance or an independence with respect to testosterone regulation. The influence of testosterone on serum PSA expression in normal men is not clear. We studied the effect of exogenous testosterone administration on the serum levels of PSA and PSMA in hypogonadal men. Serial serum PSA, serum PSMA by Western blot, and serum total testosterone levels were obtained at intervals of every 2–4 weeks in 10 hypogonadal men undergoing treatment with exogenous testosterone, delivered as testosterone enanthate injection or by testosterone patch. Linear and quadratic orthogonal polynomial scores were calculated for PSMA, PSA, and testosterone. A 2-tailed, paired t-test failed to demonstrate a significant correlation between serum PSA (linear P = 0.432, quadratic P = 0.290) or PSMA (linear P = 0.162, quadratic P = 0.973) and serum testosterone levels. This study suggests that in hypogonadal men, neither PSMA nor PSA expression is testosterone-dependent.     

Elevated levels of a high molecular weight antigen detected by antibody W1 in sera from breast cancer patients

A novel screening assay was used to test 13 previously described antibreast cancer antibodies for those which recognize antigens elevated in serum of breast cancer patients. Binding of three of these antibodies to breast or lung carcinoma cells was inhibited to a significantly greater extent by tumor patient serum than by normal serum, suggesting that the antigens might be useful serum markers. Two of these antibodies, W1 and W9, were shown to recognize nonoverlapping epitopes on a high molecular weight molecule(s) purified from serum from breast cancer patients. A sensitive double determinant immunoassay was developed to measure W1 antigen levels in sera from a total of 389 cancer patients and controls. Forty seven % (37 of 79) of individuals having breast cancer showed elevated serum levels of the W1 antigen, whereas only 4% (1 of 25) of normal controls and 2% (1 of 47) of patients hospitalized for nonmalignant disorders showed elevated levels. These differences were statistically significant (P less than 0.001). The percentage of breast cancer patients showing elevated serum levels was greater for individuals with metastatic disease. Statistically significant numbers of lung, ovarian, and prostate, but not colon, cancer patients also had elevated serum levels of the W1 antigen. These data suggest that measurement of the W1 antigen in serum might provide clinically useful information on the course of metastatic breast and other cancers.     

Pro-inflammatory cytokines and prostate-specific antigen in hyperplasia and human prostate cancer

Background: The aim of this study was to relate the expression, analyzed by Western blot and immunohistochemistry, of several pro-inflammatory cytokines, including IL-1, IL-6 and TNF-α, with serum levels of prostate-specific antigen (PSA) in normal and pathologic (hyperplasia and cancer) prostate tissues to elucidate their possible role in tumor progression. We are also discussing the possible use of these cytokines as a potential therapeutic target. Methods: The study was carried out in 5 normal, 25 benign prostatic hyperplastic (BPH) and 17 cancerous human prostates (PC). Immunohistochemical and Western blot analysis were performed. Serum levels of PSA were assayed by an immulite autoanalyzer. Results: The most relevant results showed that in BPH, IL-1α, IL-6 and tumor necrosis factor (TNF) were only expressed in patients with PSA serum levels of 0-4 or 4-20 ng/ml, but not in the group >20 ng/ml. In PC these cytokines were only expressed in patients with PSA serum levels >4 ng/ml. Conclusions: In PC there was an association between the high expression of pro-inflammatory cytokines (TNFα, IL-6, IL-1), elevated serum levels of PSA and cancer progression. A better understanding of the biologic mechanism of this association may provide new targets for therapy in these patients.     

Prostate-related antigen-derived new peptides having the capacity of inducing prostate cancer-reactive CTLs in HLA-A2+ prostate cancer patients

Prostate-related antigens, including prostate-specific membrane antigen (PSMA) and prostatic acid phosphatase (PAP), can be targets in specific immunotherapy for prostate cancer. In this study, we attempted to newly identify epitope peptides from these 2 antigens, which are immunogenic in human histocompatibility leukocyte antigen (HLA)-A2+ prostate cancer patients. Twenty-nine peptides (PSMA with 15 and PAP with 14) were prepared based on the HLA-A2 binding motif. Based on our previous finding that antigenic peptides recognized by both cellular and humoral immune systems are useful for peptide-based immunotherapy, peptide candidates were screened first by their ability to be recognized by immunoglobulin G (IgG), and then by their ability to induce peptide-specific cytotoxic T lymphocytes (CTLs). As a result, PSMA441-450 and PAP112-120 peptides were found to be frequently recognized by IgG in plasma from prostate cancer patients. These 2 candidates effectively induced HLA-A2-restricted and prostate cancer-reactive CTLs in HLA-A2+ prostate cancer patients with several HLA-A2 subtypes. In addition, their cytotoxicity was mainly dependent on peptide-specific and CD8+ T cells. These results indicate that these PSMA441-450 and PAP112-120 peptides could be promising candidates for peptide-based immunotherapy for HLA-A2(+) prostate cancer.     

Serum proteomic patterns for detection of prostate cancer

Pathologic states within the prostate may be reflected by changes in serum proteomic patterns. To test this hypothesis, we analyzed serum proteomic mass spectra with a bioinformatics tool to reveal the most fit pattern that discriminated the training set of sera of men with a histopathologic diagnosis of prostate cancer (serum prostate-specific antigen [PSA] > or =4 ng/mL) from those men without prostate cancer (serum PSA level <1 ng/mL). Mass spectra of blinded sera (N = 266) from a test set derived from men with prostate cancer or men without prostate cancer were matched against the discriminating pattern revealed by the training set. A predicted diagnosis of benign disease or cancer was rendered based on similarity to the discriminating pattern discovered from the training set. The proteomic pattern correctly predicted 36 (95%, 95% confidence interval [CI] = 82% to 99%) of 38 patients with prostate cancer, while 177 (78%, 95% CI = 72% to 83%) of 228 patients were correctly classified as having benign conditions. For men with marginally elevated PSA levels (4-10 ng/mL; n = 137), the specificity was 71%. If validated in future series, serum proteomic pattern diagnostics may be of value in deciding whether to perform a biopsy on a man with an elevated PSA level.     

血清缓激肽与前列腺癌的相关性研究

目的 探讨血清缓激肽在前列腺癌的诊断及鉴别诊断中的临床应用价值.方法 收集68例前列腺癌患者和32例前列腺增生患者,以同期体检的健康男性32例为对照组,收集其血清,酶联免疫吸附试验(enzymelinked immuno sorbent assay,ELISA)法检测血清中的缓激肽水平,比较各组血清缓激肽水平的差异以及前列腺癌患者在不同年龄、临床分期、病理分期(Gleason评分)、前列腺特异抗原(prostate specific antigen,PSA)水平、肿瘤体积以及骨转移、淋巴结转移、局部侵犯与否状态下血清缓激肽水平的差异.比较血清缓激肽与PSA联合诊断前列腺癌和PSA独立诊断前列腺癌的敏感度差异.结果 前列腺癌组血清缓激肽水平[(16.44 ±0.91) μg/L]低于对照组[(19.72±1.10) μg/L]和前列腺增生组[(20.93±1.80) μg/L],差异均具有统计学意义(均P＜0.05).在肿瘤体积较大的前列腺癌患者血清缓激肽水平较低(P＜0.05),而血清缓激肽水平在年龄、肿瘤临床分期、病理分期(Gleason评分)、PSA水平及骨转移、淋巴结转移、局部侵犯与否方面比较差异均无统计学意义(均P＞0.05).血清缓激肽与PSA联合诊断前列腺癌较单独诊断敏感度提高(P＜0.05).结论 前列腺癌患者血清缓激肽表达水平较低,且与肿瘤体积相关.血清缓激肽与PSA联合诊断前列腺癌敏感度较单独诊断高.     

Diagnostic Efficacy of PSMA and PSCA mRNAs Combined to PSA in Prostate Cancer Patients

Background: Serum Prostate-specific antigen (PSA) has been used for screening and diagnosis of prostate cancer (PCa) but it is burdened by its low accuracy, creating a need for reliable diagnostic markers. Despite prostate-specific membrane antigen (PSMA) and prostate stem cell antigen (PSCA) being widely expressed in the tissue of PCa, no definite conclusion regarding their use as clinical biomarkers due to their lacking organ specificity. Therefore, this study aimed to evaluate the peripheral blood levels of PSMA and PSCA mRNAs and examine their diagnostic significance as non-invasive integrated markers.Materials and Methods: 125 subjects were enrolled in this study. They were divided into 25 healthy controls, 25 BPH patients, and 75 PCa patients. The expression levels of PSMA and PSCA were determined using quantitative RT- PCR, in addition to measuring serum PSA.Results: Levels of PSMA and PSCA were over-expressed in PCa patients compared to controls and BPH patients and were found to be associated with increased susceptibility to PCa. Moreover, the diagnostic values of PSMA and PSCA to distinguish PCa patients from BPH patients and controls were inferior to that of PSA. However, the combination of PSMA and PSCA with PSA enhanced the efficacy of the latter.Conclusion: This study suggests that these genes were associated with malignant susceptibility. Concerning the duality of PSMA-PSA or PSCA-PSA, this implies the significance of their investigation together in peripheral blood of prostate patients.     

Detection of circulating adenocarcinoma-associated antigen in the sera of cancer patients with a monoclonal antibody

The antigen (YH206 antigen) corresponding to the monoclonal antibody (MoAb) YH206 (IgM), which was produced against a lung adenocarcinoma cell line A549, was found to be an extremely high-molecular-weight protein of over 330,000 daltons by means of SDS-PAGE and Western blot analysis. The immunohistological distribution of the antigenic determinant recognized by MoAb YH206 was found to be limited to adenocarcinoma tissues. It was shown by reversed passive hemagglutination assay (RPHA) that the antigen could be detected not only in the spent medium from human lung cancer cell line A549 but also in the sera from cancer patients. Only 3 out of 30 (10%) healthy donors and 4 of 31 (12.9%) patients with benign diseases had serum antigen levels of more than 1/64 dilution. In contrast, 42 of 87 (48.3%) patients with lung cancer and 29 of 50 (58.0%) patients with cancers of the digestive organs had elevated levels of the antigen. As regards the relation between antigen levels and clinical stages of lung cancer, values of more than 1/128 dilution were detected only in patients with stage III or IV disease.     

DNA vaccines: an active immunization strategy for prostate cancer

Immunotherapy is currently being investigated as a treatment for patients with asymptomatic, recurrent prostate cancer manifested only by a rising prostate-specific antigen (PSA) level. Several different approaches to active immunization against antigens found on cancer cells have been explored. Immunization with DNA overcomes many of the obstacles noted in previous studies. Injection of plasmid DNA encoding a xenogeneic differentiation antigen (prostate-specific membrane antigen [PSMA]) is a potent means to induce antibody and T-cell responses to these otherwise poorly immunogenic self proteins. Use of the xenogeneic DNA (ie, human PSMA DNA injected into mouse) has been shown to be an absolute requirement to overcome immunologic tolerance. We are currently conducting a phase I trial of human and mouse PSMA DNA vaccines in patients with recurrent prostate cancer, based on preclinical experiments described below.     

Alpha-2-macroglobulin deficiency in patients with advanced prostate cancer

Four out of approximately 36,000 specimens, examined by immunoelectrophoresis, showed no precipitin line of alpha-2-macroglobulin (alpha 2M) with anti-whole human serum and antiserum to alpha 2M. Serum alpha 2M levels were below 10 mg/100 ml with single radial immunodiffusion. These cases were diagnosed as having prostate cancer based on prostate biopsy. After estrogen or anti-androgen therapy, the initially severe deficiency of alpha 2M changed toward normal limits. Phytohemagglutinin (PHA)-induced lymphocytes from patients with severe alpha 2M deficiency revealed normal response. Sera from patients with alpha 2M deficiency and healthy subjects (serum alpha 2M concentration of 8-208 mg/100 ml) did not suppress lymphocyte response to PHA, while purified alpha 2M from fetal cord and healthy sera, and serum from a patient with advanced urinary cancer (serum alpha 2M concentration above 360 mg/100 ml) to PHA-induced lymphocytes demonstrated a dose-dependent suppression. Thus, these results indicate that alpha 2M in elevated concentration results in decreased PHA-induced lymphocyte response and suggest that alpha 2M may have, principally suppressive, immunoregulatory properties in vivo.     

Pro-inflammatory cytokines and prostate-specific antigen in hyperplasia and human prostate cancer

Background: The aim of this study was to relate the expression, analyzed by Western blot and immunohistochemistry, of several pro-inflammatory cytokines, including IL-1, IL-6 and TNF-α, with serum levels of prostate-specific antigen (PSA) in normal and pathologic (hyperplasia and cancer) prostate tissues to elucidate their possible role in tumor progression. We are also discussing the possible use of these cytokines as a potential therapeutic target. Methods: The study was carried out in 5 normal, 25 benign prostatic hyperplastic (BPH) and 17 cancerous human prostates (PC). Immunohistochemical and Western blot analysis were performed. Serum levels of PSA were assayed by an immulite autoanalyzer. Results: The most relevant results showed that in BPH, IL-1α, IL-6 and tumor necrosis factor (TNF) were only expressed in patients with PSA serum levels of 0–4 or 4–20 ng/ml, but not in the group >20 ng/ml. In PC these cytokines were only expressed in patients with PSA serum levels >4 ng/ml. Conclusions: In PC there was an association between the high expression of pro-inflammatory cytokines (TNFα, IL-6, IL-1), elevated serum levels of PSA and cancer progression. A better understanding of the biologic mechanism of this association may provide new targets for therapy in these patients.