Prostate-specific antigen lewels in 1695 men without evidence of prostate cancer: Findings of the American cancer society national prostate cancer detection project

The American Cancer Society National Prostate Cancer Detection Project is a prospective, multidisciplinary, and multicenter trial to assess the potential for early detection of prostate cancer by transrectal ultrasonography (TRUS), digital rectal examination (DRE), and serum prostate-specific antigen assay (PSA). By November 1990, 2805 men between the ages of 55 and 70 years with no known signs or symptoms of prostate cancer were enrolled in the study, which is planned to run for 5 years. Annual TRUS, DRE, and PSA tests were done on these subjects, and biopsies were recommended for suspicious lesions when detected. To study the performance of PSA testing in presumed normal subjects, all men were eliminated who had (1) prostate cancer detected on their initial examinations and proven by biopsy or (2) cancer detected during the year or subsequent examinations. Additionally, all men with TRUS or DRE findings that were interpreted as suspicious for cancer but who are being followed and have not yet had biopsies done were removed from this series. This left a unique, extensively screened group of 1695 men who were free of prostate cancer, as far as could be determined. Analyses of the PSA levels in this large population in the appropriate age range for increasing risk of prostate cancer revealed several important findings. First, there was a direct relationship between serum PSA levels and estimated prostate volume for both the currently available monoclonal and polyclonal PSA assays. Individuals with benign prostatic hyperplasia and larger gland volume have a higher normal limit of PSA than men with normal gland volume. Second, analyses showed no relationship between age and PSA levels or between symptoms of prostatism and PSA levels independent of gland enlargement. It was concluded that volume-adjusted upper limits of normal PSA can be determined for different levels of specificity desired. This information may be applicable to the use of PSA in men not already suspected of having prostate cancer and may increase its effectiveness as a tool for early detection.

Effect of Combination Chemotherapy on Murine Bladder Cancer

A murine bladder tumor model was evaluated for tumor growth retardation while receiving combination chemotherapy, either 40 mg/m2 methotrexate and 35 mg/m2 cis-platinum or 500 mg/m2 cytoxan and 35 mg/m2 cis-platinum at 3-week intervals. Tumor growth was observed in the control and treated groups. A significant decrease (p less than 0.001) in tumor growth and lung metastasis was noted in the cytoxan and cis-platinum group. Although the 40 mg/m2 group treated with methotrexate and 35 mg/m2 cis-platinum showed a decrease in tumor growth, it was not significant (p greater than 0.1), and lung metastasis was greater than in the control group. Cis-platinum with cytoxan was clearly effective in retarding tumor growth and metastatic spread.

Introduction to artificial neural networks for physicians: taking the lid off the black box

BACKGROUND

Over the past 5 years, a steady stream of publications has discussed the use of artificial neural networks (ANNs) for urologic and other medical applications. The pace of this research has increased recently, and deployed products based on this technology are now appearing. Before these tools can be widely accepted by clinicians and researchers, a deeper level of understanding of ANNs is necessary. This article attempts to lay some of the groundwork needed to facilitate this familiarity.

METHODS

A short discussion of neural network history is included for background. This is followed by an in-depth discussion of how and why ANNs work. This discussion includes the relationship between ANNs and statistical regression. An investigation of issues associated with neural networks follows, applicable to both general and urologic-specific applications.

RESULTS

Neural networks are computer models that have been studied extensively for over 50 years, with prostate cancer applications since 1994. From a biological viewpoint, ANNs are artificial analogues of data structures that exist in nervous systems. From a numeric viewpoint, ANNs are matrices of numbers whose values comprise knowledge that is distilled from historic databases. Many types of neural networks are analogous to well-known statistical methods.

CONCLUSIONS

ANNs are complex numeric constructs, but no more complex than similar statistical methods. However, several issues associated with neural network derivation demand that developers apply rigorous engineering practices in their studies.

Prostate-specific antigen levels in young white and black men 20 to 45 years old

OBJECTIVES

To determine the prostate-specific antigen (PSA) levels and PSA change over time in young white and black men 20 to 45 years old.

METHODS

The Department of Defense Serum Repository, a serum bank that stores all residual serum from the military human immunodeficiency virus screening program at -25 degrees C, was sampled to obtain a total of 588 black and 588 white subjects 20 to 45 years old. This was a retrospective study with only demographic data available on the studied subjects. The samples used for this study were collected between June 24, 1988 and June 12, 1996. Individuals with a history of prostate disease were excluded by query of a centralized Department of Defense diagnosis database. Three serum specimens evenly distributed over a mean of 6 years were selected for each individual to determine the free and total PSA levels and PSA velocity. The Hybritech Tandem-E PSA assay was used for the total PSA measurement, and the Hybritech Tandem-R assay was used for the free PSA measurement.

RESULTS

The baseline serum PSA levels differed by race (P = 0.04). The median (25th, 75th percentile) baseline serum PSA levels for black men 20 to 29, 30 to 39, and 40 to 45 were 0.38 ng/mL (0.26, 0.61), 0.45 ng/mL (0.32, 0. 67), and 0.52 ng/mL (0.37, 0.73), respectively. The median baseline serum PSA levels for the same decade groups in white men were 0.38 ng/mL (0.27, 0.57), 0.45 ng/mL (0.28, 0.68), and 0.40 ng/mL (0.26, 0. 64), respectively. The PSA velocity was higher in white men than in black men (mean 2.8%/yr and 1.6%/yr, respectively, P = 0.032).

CONCLUSIONS

These results suggest that although black men 20 to 45 years old have higher baseline serum PSA levels than white men of the same age, the PSA velocity is greater in young white than in young black men. Additional work is needed to determine the clinical significance of these findings.

Development of dendritic-cell based prostate cancer vaccine

Available treatments for metastatic prostate cancer have failed to demonstrate significant curative potential. Current efforts are now directed towards developments of novel strategies for the treatment of metastatic prostate cancer. Cancer immunotherapeutic strategies utilize patient immune system components to kill cancer cells. This review discusses progress in active specific immunotherapeutic approaches as potential alternative methods in the treatment of metastatic prostate cancer. One of the newest advances in cancer immunotherapy is the use of dendritic cells as the vehicle to deliver cancer antigens for an effective in vivo T cell activation. The development of dendritic cell-based prostate cancer vaccine, as well as results of several clinical trials in prostate cancer involving the administration of peptide-pulsed autologous dendritic cell pulsed are discussed.

Isolation and characterization of monoclonal antibodies specific for protein conformational epitopes present in prostate-specific membrane antigen (PSMA)

Prostate-specific membrane antigen (PSMA) is a 750-amino acid glycoprotein highly expressed in malignant prostate tissues. PSMA reacts with the murine monoclonal antibody 7E11.C5, whose binding epitope has been mapped to the N-terminal of the protein distributed on the cytoplasmic side of the plasma membrane. We have developed murine monoclonal antibodies specific for extracellular epitopes of PSMA. Three of these antibodies--1G9, 3C6, and 4D4--display distinct binding properties consistent with their recognition of conformational epitopes within native PSMA. Results indicate this panel of antibodies binds to native full-length PSMA, but not to fusion proteins containing portions of the linear sequence of the protein. Antibody binding is greatly reduced upon heat denaturation of native PSMA, and these antibodies do not detect PSMA by Western blot. Immunoprecipitation experiments demonstrate the ability of each to bind to full-length PSMA as well as PSM', a form of the protein missing the first 57 amino acids. These results indicate each antibody is specific for an epitope within the extracellular domain, a region spanning residues 44-750. Flow cytometric experiments indicate strong specific binding to live LNCaP cells. Antibody inhibition studies demonstrate that these antibodies recognize at least two distinct epitopes. Taken together, the results demonstrate that these antibodies are specific for native protein conformational epitopes within the extracellular domain. Their properties, in particular strong binding to live cancer cells, make them ideal candidates that are clearly superior to linear sequence epitope specific antibodies for in vivo applications.

Higher-dose and less frequent dendritic cell infusions with PSMA peptides in hormone-refractory metastatic prostate cancer patients

BACKGROUND

Infusion of dendritic cells (DCs) pulsed with PSMA peptides was considered possible in hormone-refractory metastatic prostate cancer patients both with or without prior treatment with a greater number of DCs and for lesser infusions than previously administered.

METHODS

DCs + PSMA peptides in patients undergoing leukapheresis were administered monthly 1-4 times, at rates greater than 20 million DCs in 17 patients not previously treated, and in 11 patients previously treated.

RESULTS

Three partial responders and one complete responder were noted in the 17 previously untreated persons. DCs + PSMA peptides averaged 28.5 million cells (range in millions, 21.0-42.3). All responders received 3 or 4 infusions of greater than 22 million cells (3-4 times). In the previously treated group of 11 patients, DCs infused averaged 29.3 million cells (range in millions, 20-40.5). One new responder (bone scan) was noted. Two prior responders continued. Observation times were similar. Toxicity was minimal.

CONCLUSIONS

These results suggest that DCs + PSMA peptide infusions can be given with greater numbers of DCs with a lesser number of infusions (1-4 monthly) with no loss of response rates compared to those noted previously, and without increased side effects. In previously treated patients (both relapsing and nonrelapsing), adverse effects were not noted, and new responses can be anticipated to be without harmful side effects. However, the follow-up time, and number of patients in this group, were small.

Follow-up ProstaScint scans verify detection of occult soft-tissue recurrence after failure of primary prostate cancer therapy

BACKGROUND

A reliable imaging modality is required to uncover occult soft- tissue recurrence after failure of primary prostate cancer therapy. This retrospective study was done to evaluate the ability of the (111)Indium-labeled monoclonal antibody (ProstaScint(R)) scan in detection of prostatic bed recurrence and/or metastases to regional and/or distant lymph nodes.

METHODS

One hundred sequential patients were evaluated with repeated ProstaScint(R) scans because of evidence of recurrence during the course of their disease. These 100 patients were followed closely from November 1994 and April 1999, and had concurrent bone scans and serum prostate-specific antigen (PSA) evaluations. They have had hormone therapy (n = 53) and/or experienced a rising PSA after radical prostatectomy (n = 38) or after radiation therapy (n = 56). Scan images were scored 0-3, where score 0 = negative, score 1= prostate bed uptake, score 2 = regional lymph node uptake, and score 3 = distant lymph node uptake. In each patient, the uptake of the follow-up scan(s) was compared to that of the initial scan.

RESULTS

The median age was 70 years (range, 45-87), and 23 patients had a positive bone scan. The average PSA was 40.5 ng/ml (standard deviation, 223.5). There was 257 scans representing 100 patients. All patients had at least 2 scans, 35 patients had 3 scans, and 11 patients had 4 scans. No individual exhibited detectable adverse clinical reactions during or after the scan. The findings of the initial and consecutive scans were anatomically consistent in 79%, whereas in 21% there were skip metastases. In 24 patients the lesions progressed by scan and PSA, 10 patients showed progression of scan but no PSA progression, 49 patients showed no change, and 17 patients showed a remission related to adjuvant therapy.

CONCLUSIONS

The consistency on repeating the scan (79%) and the high percentage of patients showing persistent uptake at the prostate bed (43%) as well as the percentage of detection of regional nodes (20%) and distant nodes (32%) reflects the importance of using the ProstaScint(R) scan in finding occult recurrences after primary treatment failure of prostate cancer. These results are similar to those reported earlier in autopsy series studies in similar populations.

Dendritic cell-based immunotherapy of prostate cancer: immune monitoring of a phase II clinical trial

We assessed both non- and peptide-specific immune responses in prostate cancer patients before and after immunotherapy with dendritic cells exogenously pulsed with the prostate-specific membrane antigen-derived peptides, PSM-P1 and PSM-P2. For all subjects, we observed that clinical responses were strongly associated with two indicators of immunocompetence: skin test responses to recall antigens and cytokine secretion by T cells after nonspecific stimulation. In a subset of responders, we observed cytokine secretion or cytotoxicity against the immunizing peptides or an immunodominant epitope from an influenza recall antigen. The clinical results support the use of monitoring for overall immunocompetence to help determine why a patient has or has not responded to therapy. Moreover, it could be useful as an inclusion criterion to select those more likely to benefit from treatment.

Evaluation of prostate cancer patients receiving multiple staging tests, including ProstaScint scintiscans

BACKGROUND

Multiple serum tests were performed on archival samples from patients who participated in trials to assess the ProstaScint scan staging ability. Traditional statistical analysis as well as artificial neural network (ANN) analysis were employed to evaluate individual patients and the group as a whole. The results were evaluated so that each factor was tested for prognostic value.

METHODS

Data obtained from serum tests, bone scans, and ProstaScint scans were evaluated by traditional statistical methods and ANN to determine the individual value in clinical staging of prostate cancer.

RESULTS

Two hundred seventy-five patients (180 postprostatectomy, 95 intact prostate) with prostate cancer (14 with distant metastases) were available for analysis. Data available included: clinical state (remission or progression), most recent clinical TNM stage, bone scan, and ProstaScint scan. Serum was tested for prostate-specific membrane antigen(PSMA), prostate-specific antigen(PSA), free PSA (fPSA), and complexed PSA (cPSA). Additional calculations included percent free PSA, and percent complexed PSA. Spearman individual statistical assessment for traditional group evaluation revealed no significant factors for T-stage. The free PSA and complex PSA had a significant association with node (N)-status. The distant metastases (M) stage correlated well with the bone scan and clinical stage. ANN analysis revealed no significant T-stage factors. N-stage factors showed a 95% sensitivity and 49% specificity. These factors included the presence or absence of a prostate, PSA serum levels, bone scan, and ProstaScint scans as major associated indicators. ANN analysis of the important variables for M-stage included ProstaScint scan score, and PSA levels (total, percent complexed, percent free, and fPSA). These factors were associated with a 95% sensitivity and 15% specificity level.

CONCLUSIONS

Two hundred seventy-five patients receiving treatment for prostate cancer were evaluated by ANN and traditional statistical analysis for factors related to stage of disease. ANN revealed that PSA levels, determined by a variety of ways, ProstaScint scan, and bone scan, were significant variables that had prognostic value in determining the likelihood of nodal disease, or distant disease in prostate cancer patients.

Detection of extraprostatic prostate cells utilizing reverse transcription-polymerase chain reaction

This article reviews the utility of reverse transcription-polymerase chain reaction (RT-PCR) in prostate cancer. RT-PCR aims to detect occult micrometastases in non-prostatic sites. Due to its exquisite analytical sensitivity, RT-PCR is able to amplify and detect even low-level, prostate-specific messages present at these extraprostatic sites. In recent years, a fair amount of data on the clinical utility of the technique had been reported. The target tissues under investigation are peripheral blood, bone marrow aspirate, and lymph nodes. Favorite markers of choice are prostate-specific antigen (PSA), prostate-specific membrane antigen (PSMA), and human glandular kallikrein-2 (hK2). False positives among negative controls are low. For the most part, RT-PCR is inadequate in detecting tumor cells in the peripheral blood from patients who are known to have metastatic prostate cancer. All studies showed that RT-PCR could detect PSA, PSMA or hK2 mRNAs in the circulation of patients who have organ-confined or extraprostatic disease. Most studies showed that RT-PCR utilizing current markers could not be used as a prospective test to diagnose prostate cancer. However, a few studies also showed that the detection rate could be predictive and sensitive enough to differentiate patients with organ-confined disease from those with extraprostatic disease. Data from PSA- or PSMA-RT-PCR using lymph nodes as the tissue source is more encouraging. RT-PCR was able to detect PSA and/or PSMA positive samples that have not been detected by conventional pathology.

Progress in active specific immunotherapy of prostate cancer

Treatments available for metastatic prostate cancer have failed to demonstrate significant curative potential. Current efforts are now directed towards developments of novel strategies for the treatment of metastatic prostate cancer. Cancer immunotherapeutic strategies utilize patient immune system components to kill cancer cells. This review discusses progress in active specific immunotherapeutic approaches as potential alternative methods in the treatment of metastatic prostate cancer. Various methods of augmenting the immune response against prostate cancer are discussed including systemic cytokine adjuvant therapy, cytokine gene transduced tumor vaccines, non-antigen specific immunization, DNA and peptide vaccines plus adjuvants, as well as dendritic cell-based cancer vaccines.

Prostate-specific membrane antigen (PSMA): current benefits and future value

We will review the evolution, benefits, and limitations of PSMA testing in the past, as well as its current and future value. Prostate cancer has been the most frequently diagnosed cancer and the second leading cause of cancer death in men in the United States. It has a wide spectrum of biological behavior between latent (indolent) and progressive (aggressive). Further identification of prostate-specific membrane antigen (PSMA) as a prognostic proliferation marker may enhance our understanding of the types of prostate cancer. A review of PSMA testing in the past as well as currently was conducted. Studies were reviewed that deal with detection of PSMA in serum and seminal fluid, reverse transcriptase-polymerase chain reaction (RT-PCR), immunoscintigraphy, and immunohistochemical assays. PSMA is expressed primarily in benign and cancerous prostatic epithelial cells. It is up-regulated in hormone resistant states, and in metastatic situations or other clinical situations where there is tumor recurrence or extension. Based on current results, PSMA detected in the serum by western blotting can assist in the identification, staging, and monitoring of metastatic prostate cancer. In addition, PSMA shows a promising role in directed imaging and therapy of recurrent or metastatic disease.

Use of artificial neural networks in evaluating prognostic factors determining the response to dendritic cells pulsed with PSMA peptides in prostate cancer patients

BACKGROUND

Our purpose was to compare the importance of over 22 measurements used in evaluating the clinical responses of patients with metastatic or locally recurrent prostate cancer, treated by dendritic cell (DC) infusions with prostate-specific membrane antigen (PSMA) peptides.

METHODS

Artificial neural networks (ANNs) were employed for assessment, as well as the traditional methods of logistic regression.

RESULTS

Twenty-six patients with metastatic disease and 37 patients with local recurrence were available for evaluation and comparison. ANN evaluation ranked the collective effects of DC infusion, immune responses (CD3+ cells, CD16+ cells, zeta chain+ cells), and cytokines, e.g., IL-6 and PSMA levels, very highly. Logistic regression identified all of these parameters to some degree, but in a different rank order. Patients with metastases showed a sharp rate of response secondary to the level of DC infusion, in contrast to those patients with local recurrence, in which it was more gradual.

CONCLUSIONS

ANN analysis emphasizes the importance of level of DC infusion, immune parameters, cytokines, and markers such as PSMA in determining the response to PSMA peptide immunotherapy. The criteria of response were judged to be correct in 86% of metastatic patients and 83% of locally recurrent patients evaluated in this study.

Matrix metalloproteinase homologues from Arabidopsis thaliana. Expression and activity

Five genes potentially encoding novel matrix metalloproteinases (MMPs) have been identified on the Arabidopsis thaliana data base. The predicted proteins have a similar domain structure to mammalian MMP-7, with a propeptide and catalytic domain but no C-terminal hemopexin-like domain. Four of the A. thaliana MMPs (At-MMPs) have a predicted C-terminal transmembrane domain. The At-MMPs are differentially expressed in flower, leaf, root, and stem tissues from 14-day-old plants. The cDNA for one of the At-MMPs (At1-MMP) was cloned and expressed in Escherichia coli. Following refolding and purification, the proenzyme At1-MMP was shown to undergo autolytic activation in the presence of an organomercurial with a concomitant decrease in M(r). In contrast to this, trypsin-treatment led to the formation of an inactive product. The activated At1-MMP digested myelin basic protein, but was unable to digest gelatin or casein. Three peptide substrates for MMPs were also cleaved by At1-MMP. The enzyme activity of At1-MMP was inhibited by human tissue inhibitors of metalloproteinases 1 and 2 and the hydroxamate inhibitor BB-94.

American Joint Committee on Cancer prognostic factors consensus conference

BACKGROUND

The American Joint Committee on Cancer (AJCC) published the 1st edition of the Cancer Staging Manual in 1977 and began using T (tumor extent), N (regional lymph node status), and M (the presence or absence of distant metastasis) in an organized staging scheme to express the extent of disease in a number of cancer sites. The goal of this program has been to provide physicians and others with a useful methodology to plan treatment, project prognosis, and measure outcome end results. Until recent years, this system has incorporated only elements of anatomic extent of the tumors determined by clinical and pathologic methods. At the present time an increasing number of nonanatomic cancer prognostic factors are being identified and studied. Some of these factors currently are being used for outcome predictions and treatment decisions.

METHODS

To begin the process of identifying and validating these prognostic factors to refine the present TNM system, the AJCC convened a Prognostic Factors Consensus Conference to evaluate the roles of biologic, genetic, molecular, and other nonanatomic factors in staging cancer. Working groups were appointed for carcinomas of the breast, colorectum, prostate, and ovary and experts in each of these areas were invited to participate. Emphasis was placed on evaluating existing data and the correlation of these data with survival.

RESULTS

None of the groups believed that there were sufficient data at the present time to merit incorporation of serum markers into the TNM system for the four tumors under consideration, although this soon might become possible in prostate carcinoma after the evaluation of survival data from multiple institutions. Recommendations were made regarding the emerging sentinel lymph node technique, the need for an increased use of histopathology in the staging of breast and ovarian carcinomas, and the use of additional histologic staining techniques for the detection of "micrometastases" in lymph nodes. A number of additional recommendations were made for changes to the TNM system that did not involve serum markers and other nonanatomic cancer prognostic factors.

CONCLUSIONS

These recommendations are presented for the purpose of discussion and evaluation and do not yet represent formal proposals for a change in the AJCC TNM system of staging.

Review of phase II hormone refractory prostate cancer trials

In men with hormone refractory metastatic prostate cancer, single agents have demonstrated an objective response when using a response rate greater than standard treatment in prior National Prostate Cancer Project (NPCP) trials. Among these agents are methotrexate, cisplatin, 5-fluorouracil, cyclophosphamide, doxorubicin, estramustine, methyl N-(2-chloroethyl)-N'-cyclohexyl-Nnitrosourea (CCNU), 5-(3,3-dimethyl1-triazenyl)1H-imidazole-4-carboxamide (DTIC), and vinblastine. Other combinations of protocols have been previously evaluated. Currently under review is a 1 4-year follow-up on an adjuvant trial (NPCP 900/1000) where all patients had a bilateral pelvic lymphadenectomy. These patients were then randomized to surgery or radiation, and received either cyclophosphamide, estramustine, or no therapy for 2 years. Clinical results showed there was no difference in disease-free survival or survival rates between those patients in the group who had T3 prostate cancer, and those with negative pelvic lymph node dissection. The drugs diethylstilbestrol, megestrol, or streptozocin have been used. In clinical trials, the single agent diethylstilbestrol usually had a better effect. Combinations of estramustine with vinblastine were also effective when compared with the results of standard treatment. When comparing patients who relapsed from hormone refractory prostate cancer, there was no significant statistical response rate difference (P = <0.05) in patients who were offered either flutamide or estramustine. To determine more accurately the positive results from these trials, the pre-prostate-specific antigen (PSA) era of stable disease must be re-evaluated.

The National Cancer Data base Report on increased use of brachytherapy for the treatment of patients with prostate carcinoma in the U.S

BACKGROUND

An increase in the proportion of prostate carcinomas diagnosed at early, potentially curable stages has led to several changes in treatment of patients with this disease. Greater use of radical prostatectomy and external beam radiation has been documented, and recent data suggest that the use of radiation implant (brachytherapy) also has increased. Recent results from the National Cancer Data Base (NCDB) are available to explore this trend in greater detail.

METHODS

Data provided by 1758 hospital cancer registries for 435,264 patients diagnosed between 1992 and 1996 were studied. Reported use of brachytherapy was analyzed by year of diagnosis, region, patient age at diagnosis, and tumor grade.

RESULTS

The proportion of all prostate carcinoma patients treated with brachytherapy increased from 1.4% in 1992 to 3.0% in 1995. Ninety-six percent of brachytherapy patients were American Joint Committee on Cancer Stage I or II (with tumors classified as T1 or T2). As a proportion of patients in a stage group, the use of brachytherapy was greatest in Stage I; 3.7% of patients in this stage were treated by this modality. The increase in brachytherapy also was greatest among Stage I patients, rising from 2.0% in 1992 to 5.8% in 1996. Rates of use were greatest in the northeastern and southeastern U.S. and least frequently reported by institutions in the Midwest and the South. Brachytherapy was used across a wide range of patient age groups. Analysis by grade showed that 89.8% of patients treated with brachytherapy had well-differentiated or moderately differentiated tumors.

CONCLUSIONS

Brachytherapy represented a small component of the overall pattern of care for prostate carcinoma patients in the U.S. during the interval studied. However, the rate of use of this modality for patients with localized prostate carcinoma increased substantially over the 5-year interval. This may reflect a trend toward more conservative management of prostate carcinoma. Additional monitoring and analysis of the more recent use of brachytherapy for the treatment of prostate carcinoma patients is warranted.

Antisense human neuroglia related cell adhesion molecule hNr-CAM, reduces the tumorigenic properties of human glioblastoma cells

BACKGROUND

Human Nr-CAM (Neuroglia related Cell Adhesion Molecule) is over expressed in glioblastoma multiforme tissue (GMT) as compared to normal brain tissue (NBT).

MATERIALS AND METHODS

We transfected a human glioblastoma cell line (2020-CRL) with a vector that overexpresses antisense hNr-CAM using a CMVpromoter.

RESULTS

Antisense hNr- CAM caused reduction in the native hNr-CAM expression, changed cell morphology, reduced the cell proliferation rate and lengthening of the cell cycle. Furthermore, antisense hNr-CAM overexpression in these cells caused extensive reduction in the number of soft agar colonies and invasion through extra cellular matrix (ECM) gel in vitro. Subcutaneous injection of antisense hNr-CAM overexpressing glioblastoma cells into nude mice caused complete inhibition of tumor formation as compared to vector only transfected cells. Intra-tumoral inoculation of antisense hNr-CAM expressing plasmid also caused slow tumor growth in nude mice in vivo.

CONCLUSION

On the basis of these results, we conclude that hNr-CAM is a valid target for potential gene therapy of glioblastoma tumors.

Circulating levels of interleukin-6 in patients with hormone refractory prostate cancer

BACKGROUND

Interleukin-6 (IL-6) is a cytokine that plays a central role in host defense due to its wide range of immune and hematopoietic activities. It is found in high levels in human ejaculate, and has recently been found to regulate prostate-specific protein expression in prostate cancer cells through nonsteroidal activation of the androgen receptor. IL-6 may be a candidate mediator of morbidity in patients with metastatic disease. We attempted to evaluate the potential of circulating IL-6 levels as a marker of disease progression. MATERIALS AND METHODS Serum IL-6, prostate specific antigen (PSA), percent free PSA (%fPSA), and prostate-specific membrane antigen (PSMA) were measured using commercially available assays in 407 men, including 15 controls. The rest of the study population had clinical or histologic evidence of prostate diseases, including 41 patients with chronic prostatitis, 167 with benign prostatic hyperplasia (BPH), 8 with high-grade prostatic intraepithelial neoplasia (PIN), 88 with localized prostate cancer, 22 with local recurrence after treatment of primary tumor, 4 with advanced untreated disease (nodal or bony metastases), 23 with advanced hormone dependent disease, and 39 with advanced hormone refractory disease (PSA > 1.0 ng/ml while on hormone treatment and/or evidence of disease progression). None had history of concurrent malignancy or acute inflammatory condition. Kruskal-Wallis analysis of variance and Spearman's correlation analysis were used for statistical analyses.

RESULTS

Serum levels of IL-6 were significantly elevated in patients with clinically evident hormone refractory disease (5.7 +/- 1.9 pg/ml) and statistical significance was seen when comparing the elevated serum IL-6 levels to those in normal controls, prostatitis, BPH, and localized and recurrent disease, (P values < 0.01). Compared to serum levels of controls and BPH, PSA was significantly elevated in advanced untreated disease and hormone refractory groups (P < 0.05). Percent fPSA was significantly lower in all cancer patients but the hormone refractory. Serum PSMA was elevated in advanced untreated prostate cancer. Serum IL-6 showed positive correlation with PSMA and negative correlation with serum PSA but did not attain statistical significance.

CONCLUSIONS

Serum IL-6 levels are significantly elevated in hormone-refractory prostate cancer patients and may be a surrogate marker of the androgen independent phenotype.

'Green revolution' genes encode mutant gibberellin response modulators

World wheat grain yields increased substantially in the 1960s and 1970s because farmers rapidly adopted the new varieties and cultivation methods of the so-called 'green revolution'. The new varieties are shorter, increase grain yield at the expense of straw biomass, and are more resistant to damage by wind and rain. These wheats are short because they respond abnormally to the plant growth hormone gibberellin. This reduced response to gibberellin is conferred by mutant dwarfing alleles at one of two Reduced height-1 (Rht-B1 and Rht-D1) loci. Here we show that Rht-B1/Rht-D1 and maize dwarf-8 (d8) are orthologues of the Arabidopsis Gibberellin Insensitive (GAI) gene. These genes encode proteins that resemble nuclear transcription factors and contain an SH2-like domain, indicating that phosphotyrosine may participate in gibberellin signalling. Six different orthologous dwarfing mutant alleles encode proteins that are altered in a conserved amino-terminal gibberellin signalling domain. Transgenic rice plants containing a mutant GAI allele give reduced responses to gibberellin and are dwarfed, indicating that mutant GAI orthologues could be used to increase yield in a wide range of crop species.

Follow-up evaluation of a phase II prostate cancer vaccine trial

BACKGROUND

A phase II trial, involving infusions of autologous dendritic cells (DC) and two human histocompatibility antigen (HLA-A2)-specific prostate-specific membrane antigen (PSMA) peptides, was recently completed. Thirty percent of the participants, including subjects with hormone-refractory metastastic disease, and those with suspected local recurrence of prostate cancer, were identified as clinical responders. This report describes the follow-up evaluation of 19 responders in the two study groups.

METHODS

After conclusion of the study, study participants were subjected to follow-up evaluations at 6-8-week intervals. Each responder was reevaluated for response status, and duration of response was determined.

RESULTS

Subjects were observed for an average of 291 days (metastastic group, group A-2) and 557 days (local recurrence group, group B), which included the treatment and follow-up periods. The average duration of response was 149 days for group A-2, and 187 days for group B. A majority of responders (11/19; 58%) were still responsive at the end of the current follow-up.

CONCLUSIONS

The responses observed may be significant and relatively durable. This study suggests that DC-based cancer vaccines in the future may provide an additional therapy for advanced prostate cancer.

Expression and purification of prostate-specific membrane antigen in the baculovirus expression system and recognition by prostate-specific membrane antigen-specific T cells

Antigen-specific immunotherapy of cancer depends on a consistent source of well-defined protein antigen. Production of recombinant protein offers the obvious solution to this problem but few comparisons of recombinant and native proteins in cellular immune assays have been reported. We report expression of a putative immunotherapy antigen, prostate-specific membrane antigen (PSMA), in insect cells using a baculovirus vector. T cells stimulated with recombinant PSMA or native PSMA derived from the LNCaP cell line recognized both native PSMA and recombinant, baculoviral PSMA. These data indicate that PSMA produced in Sf9 cells is immunologically cross-reactive with native PSMA and therefore suitable for immunotherapy as it is recognized by both cellular and humoral immune responses.

GM-CSF as a systemic adjuvant in a phase II prostate cancer vaccine trial

BACKGROUND

Recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF; Leukine [sargramostim], Immunex Corp., Seattle, WA) was administered to a subgroup of 44 patients in a phase II clinical trial for prostate cancer using DC pulsed with HLA-A2-specific prostate-specific membrane antigen (PSMA) peptides. Our purpose was to determine if GM-CSF caused any enhancement of patients' immune responses, including enhancement of clinical response to the DC-peptide treatment. This report compares the clinical responses to DC-peptide infusions with and without systemic GM-CSF treatment.

METHODS

GM-CSF was administered by subcutaneous injection at a dose of 75 microg/m2/day for 7 days with each of six infusion cycles. Prefilled syringes were supplied to the patients for self-administration.

RESULTS

One complete and 8 partial responders were identified among 44 patients who received GM-CSF, as compared to 2 complete and 17 partial responders among 51 patients who did not receive GM-CSF. For patients who received GM-CSF and were tested by delayed-type hypersensitivity (DTH) skin test, 3 cases of improved immune response were identified, compared to 5 cases of improvement in patients who did not receive GM-CSF. The main GM-CSF side effects reported were local reactions at the site of injection, fatigue, pain, and fever. Most reported side effects were of mild severity, with some cases of moderate severity leading to discontinuation of GM-CSF.

CONCLUSIONS

Our results suggest GM-CSF as employed in this trial did not detectably enhance clinical response to DC-peptide infusions, or significantly enhance the measured immune response.

Association of free PSA percent, total PSA, age, and gland volume in the detection of prostate cancer

BACKGROUND

Measurement of the free fraction of total prostate-specific antigen (fPSA%) has been proposed as a useful addition to total PSA for the detection of prostate cancer.

METHODS

We assessed the performance of fPSA% in differentiating men with prostate cancer from men without cancer in a group of 1,709 subjects studied in five institutions.

RESULTS

On the basis of PSA testing, digital rectal examination, and ultrasound examination conducted at one or more visits, 229 cancers were diagnosed. The mean fPSA% in men with cancer was 9.1% compared to 18.9% in men without cancer. The fPSA% varied by age, with men under 60 having a mean fPSA of 13.9% compared to 17.5% in men 60-69 years old and 19.8% in men over age 70. Significant associations of fPSA% with gland volume and PSA level were also observed. The sensitivity, specificity, and positive predictive value of different fPSA% cutoff levels were assessed in 513 men who underwent sextant biopsy. Sensitivity of 85.4%, 32.1% specificity, and a 39.2% positive predictive value were observed using an fPSA cutoff of 15% in men with PSA in the 4.0-9.9 ng/ml range. Sensitivity of 96.9%, 12.3% specificity, and a 36.2% positive predictive value were observed using an fPSA cutoff of 20% in the same men. If 15% fPSA had been used as a biopsy criterion in men with PSA of 4.0-9.9 ng/ml, the number of biopsies performed could have been reduced by 21.2%, with a concomitant reduction in cancer detection of 14.6%. Using a 20% fPSA criterion, biopsies would have been reduced 12.7%, with a 3.1% reduction in cancer detection.

CONCLUSIONS

These results provide some evidence that the detection of prostate cancer is enhanced by measuring fPSA% in addition to the established measure of total PSA level. Further research is needed to identify other markers that have better sensitivity and specificity.

Vaccine therapy for prostate cancer

Vaccine therapy may provide an alternative for prostate cancer patients whose disease no longer responds to hormone therapy. Administration of dendritic cells pulsed with prostate-specific membrane antigen (PSMA) induces cellular immune responses against the tumor with virtually no adverse effects. About 30% of the evaluable patients were identified as partial responders, based on the National Prostate Cancer Project (NPCP) criteria. In addition, there was a 50% decrease of serum prostate-specific antigen or resolution of previously measurable lesions on imaging. Dendritic cell vaccine therapy may have a synergistic effect, when combined with other therapies.

Clinical highlights from the National Cancer Data Base, 1999

The National Cancer Data Base (NCDB), a joint project of the Commission on Cancer of the American College of Surgeons and the American Cancer Society, collects and analyzes data from a wide variety of sources throughout the United States, including small community hospitals. Due to this unique reporting system, individual facilities can compare their own data with the aggregate data from the NCDB, using their findings to evaluate local patient care practices. This article highlights the principal findings of the NCDB and Patient Care Evaluation articles published in 1998 on breast, prostate, cervical, endometrial, gallbladder, head and neck, nasopharyngeal, rectal, thyroid, and vaginal cancers, as well as on melanoma, brain tumors, and Hodgkin's disease. With more than five million cancer cases in the NCDB for the years between 1985 and 1995, sufficient numbers of even rare cancers have been accrued to permit some types of epidemiologic and clinical assessments.

Phase II prostate cancer vaccine trial: report of a study involving 37 patients with disease recurrence following primary treatment

BACKGROUND

A phase II trial was conducted to assess the efficacy of infusions of dendritic cells (DC) and two HLA-A2-specific prostate-specific membrane antigen (PSMA) peptides (PSM-P1 and -P2). This report describes the evaluation of 37 subjects admitted with presumed local recurrence of prostate cancer after primary treatment failure.

METHODS

All subjects received six infusions of DC pulsed with PSM-P1 and -P2 at 6-week intervals. Clinical monitoring was conducted pre-, during, and post-phase II study. Data included: complete blood count, bone and total alkaline phosphatase, prostate markers, physical examination, performance status, bone scan, ProstaScint scan, and chest X-ray, as well as other assays to monitor cellular and humoral immune responses.

RESULTS

One complete and 10 partial responders were identified from this group based on National Prostate Cancer Project criteria, or on a 50% reduction of prostate-specific antigen (PSA), or on a significant resolution in lesions (biopsy-proven when possible) on ProstaScint scan.

CONCLUSIONS

About 30% of study participants in this group showed a positive response at the conclusion of the trial. This study suggests that DC-based cancer vaccines may provide an alternative therapy for prostate cancer patients whose primary treatment failed.

Dendritic cell-based immunotherapy for prostate cancer

Dendritic cells are unique in their ability to stimulate naive T cells. These investigators have developed a prostate cancer vaccine using autologous dendritic cells as a vehicle to present prostate antigens to T cells in vivo.

Infusion of dendritic cells pulsed with HLA-A2-specific prostate-specific membrane antigen peptides: a phase II prostate cancer vaccine trial involving patients with hormone-refractory metastatic disease

BACKGROUND

A phase II trial was conducted to assess the efficacy of infusions of dendritic cells (DC) and two HLA-A2-specific PSMA peptides (PSM-P1 and -P2). This report describes thirty three subjects with hormone-refractory metastatic prostate cancer without prior vaccine therapy history who were evaluated and reported as a group.

METHODS

All subjects received six infusions of DC pulsed with PSM-P1 and -P2 at six week intervals. Clinical monitoring was conducted pre-, during, and post- phase II study. Data collected include: complete blood count, bone and total alkaline phosphatase, prostate markers, physical examination, performance status, bone scan, ProstaScint scan, chest x-ray, as well as assays to monitor cellular immune responses.

RESULTS

Six partial and two complete responders were identified in the phase II study based on NPCP criteria, plus 50% reduction of prostate-specific antigen (PSA), or resolution in previously measurable lesions on ProstaScint scan.

CONCLUSIONS

Over 30% of study participants in this group showed a positive response at the conclusion of the trial. This study suggested that DC-based cancer vaccines may provide an alternative therapy for prostate cancer patients whose disease no longer responds to hormone therapy.

Regional diversity and breadth of the National Cancer Data Base

BACKGROUND

The National Cancer Data Base (NCDB), a joint project of the Commission on Cancer of the American College of Surgeons and the American Cancer Society, is a cancer management and outcomes data base for health care organizations. It provides a comparative summary of patient care that is used by participating hospitals and communities for self-assessment. This article describes the most current (1995) data.

METHODS

Since 1989, 7 calls for data have been issued, yielding a total of 5,558,389 cancer patient reports for the years 1985-1995. A total of 1849 hospital cancer registries have participated in at least 1 of the calls for data.

RESULTS

One thousand one hundred and fourteen hospitals from 50 states and the District of Columbia reported 655,627 cases for the diagnosis year 1995. The hospitals represented a wide range of sizes (187 [16.8%] with 1000+ cases annually, 405 [36.4%] with 500-999 cases annually, 255 [22.9%] with 300-499 cases annually, 211 [18.9%] with 100-299 cases annually, and 56 [5%] with < 100 cases annually) and types (21 [1.9%] National Cancer Institute [NCI]-recognized cancer centers, 119 [10.7%] government hospitals, 102 [9.2%] teaching hospitals, 256 [23.0%] large community hospitals, 297 [26.7%] medium/small community hospitals, and 257 [23.1%] nongovernmental hospitals without approval status from the Commission on Cancer or NCI recognition). Remarkably similar distributions of cases by primary site and age were reported from each of six U.S. geographic regions. In addition, within each of these six regions, the cases were reported from a wide range of income strata and ethnicities. For several states, relatively few cancer cases were reported. For several examples of relatively rare patient and tumor groups, all reported cases between 1985-1995 included potentially useful quantities of patients in whom further study of such special groups was warranted.

CONCLUSIONS

The authors conclude that the reported cases most likely are representative at the regional (but not state) level of cancer patients diagnosed and treated at U.S. hospitals with regard to types of cancer and ages of the patients. They conclude further that cancer reporting may be quite diverse within each region with regard to other known patient and reporting institution characteristics.

ProstaScint scan may enhance identification of prostate cancer recurrences after prostatectomy, radiation, or hormone therapy: analysis of 136 scans of 100 patients

BACKGROUND

Primary extraprostatic spread or failure after prostate cancer treatment can occur locally in the prostatic fossa and/or metastasize to regional and/or distant lymphatics and/or in bone. We evaluated the ability of the ProstaScint (Cytogen Corp., Princeton, NJ) scan to identify soft tissue recurrence of prostate cancer in patients who failed primary treatment, and we monitored their responses to a secondary treatment.

METHODS

The 111indium-labeled monoclonal antibody (ProstaScint) was evaluated in a series of 136 consecutive scans associated with a complete set of relevant clinical and biochemical data. These scans represented 100 patients, imaged between November 1994-May 1998, who underwent a definitive prostate cancer treatment followed by evidence of recurrence. All patients had serum prostate-specific antigen (PSA), Western-blot serum prostate-specific membrane antigen (PSMA), and bone scans. Prostatic fossa and/or lymph node biopsies were available in 33 patients.

RESULTS

Overall, no adverse reactions were related to any of the radioactive antibody infusions. The average age was 69 years (range, 48-89 years), serum PSA was 55.9 ng/ml (range, 0-2,185 ng/ml), and serum PSMA was 0.32 (relative intensity levels range, 0.04-0.55). The initial therapies given were radical prostatectomy (55 scans), prostate radiation (74 scans), and/or hormonal therapy (77 scans). Twelve patients exhibited a negative scan. Local recurrence alone was identified in 58 scans (42.6%). Lymph node metastases were identified in 66 scans (48.5%). Of these, 21 had regional metastases alone, and 45 had distant lymph node metastases. Ten scans showed skip lymph node metastases without regional failure. PSA significantly correlated with negative, pelvic, and extrapelvic scan findings (P < or = 0.02). PSMA correlated best with pelvic recurrence and extrapelvic metastases in prostatectomized patients. Thirty-four patients had repeated scans for monitoring treatment response. Of these patients, 19 (56%) showed progression on the second scan, consistent with persistent increase in PSA and PSMA levels in all but 2 patients. Another 11 patients showed no change, and 4 patients showed partial remission, suggesting a response to the salvage treatment. All 20 positive prostate biopsies and 4 of the 7 positive lymph node biopsies correlated with ProstaScint findings, whereas 4 of the 6 patients with a negative biopsy had negative scans (i.e., 89% sensitivity and 67% specificity). Bone metastases were identified in 42 bone scans; 45% of these showed no lymph node metastasis on ProstaScint. In another 24 patients (57%), bone metastases were detected on ProstaScint examinations.

Current evaluation of the tissue localization and diagnostic utility of prostate specific membrane antigen

BACKGROUND

Current statistics indicate that prostate carcinoma is the most common form of cancer diagnosed in American men, resulting in the second highest cancer death rate. Early diagnosis and accurate staging are imperative given that there is little effective treatment for metastatic disease, especially after androgen deprivation therapy fails. Identification of new biochemical markers for disease progression will provide important tools for diagnosis and monitoring. One such potential marker is prostate specific membrane antigen (PSMA).

METHODS

A review was conducted to identify reports concerning evaluation of diagnostic applications of PSMA.

RESULTS

PSMA is a membrane-bound glycoprotein that is highly restricted to the prostate. Immunohistochemical findings indicate that PSMA is a marker of epithelial cells of the prostate. This expression is increased in association with prostate carcinoma, particularly in hormone-refractory disease. Given its membrane-bound character, PSMA has been exploited as a marker for tumor detection by immunoscintiscanning with the 111In-labeled anti-PSMA monoclonal antibody 7E11.C5. Increased concentrations of 7E11.C5-reactive antigen are present in the serum of prostate carcinoma patients compared with healthy individuals; also, hematogenous circulating prostate carcinoma cells are detectable with reverse transcriptase-polymerase chain reaction analysis with primers specific for PSMA. New monoclonal antibodies specific for extracellular portions of the PSMA molecule currently are being utilized in applied studies.

CONCLUSIONS

PSMA is a widely used marker for prostate epithelial cells. Its up-regulation in association with cancer, particularly in advanced cancer, is ideal for application as a prognostic marker. A variety of promising clinical applications utilizing PSMA have been or are being developed. In the future, these promise to have an important impact on cancer diagnosis and patient treatment.

Molecular characterization of CXCR-4: a potential brain tumor-associated gene

BACKGROUND AND OBJECTIVES

We have previously reported the isolation of a G protein-coupled receptor, CXCR-4, that is overexpressed in glioblastoma multiforme tumor tissue (GMTT), as compared to normal brain tissue (NBT).

METHODS

Gene-specific RT-PCR, Northern blotting, and in situ hybridization techniques were used to study its expression in a variety of normal tissues, tumor tissues, and cell lines, as well as during development. Antisense CXCR-4 was overexpressed in glioblastoma cells to study its effect on cell proliferation.

RESULTS

Gene-specific RT-PCR analysis indicated that the CXCR-4 gene is overexpressed in several malignant glioma tissues, breast tumor tissues and cell lines. Northern blot analysis indicated that CXCR-4 is expressed at high levels in certain leukemias, uterine cancer, and Burkitt's lymphoma cell line. The occipital and temporal lobe showed high levels of CXCR4 in normal human brain. The CXCR-4 gene was expressed in all organs in the early stages of development (days 8-10). In adult mouse, CXCR-4 is expressed only in brain, spinal cord, bone marrow, and pituitary gland. Antisense CXCR-4 overexpression in glioblastoma cells caused inhibition of cell proliferation and induction of cellular differentiation in vitro. This suggests that CXCR-4 expression may play an important role during embryonic development and also in the genesis of human gliomas.

CONCLUSIONS

On the basis of CXCR4 expression data and antisense overexpression data, we conclude that CXCR-4 plays an important role in the tumorigenic properties of brain, breast, and other tumor types. On the basis of its unique expression during mouse development, we conclude that it may play an important role in the normal functioning of brain, spinal cord, and bone marrow during development.

Isolation and characterization of monoclonal antibodies specific for the extracellular domain of prostate specific membrane antigen

PURPOSE

Monoclonal antibodies specific for protein epitopes of prostate specific membrane antigen (PSMA) expressed on the external surface of prostatic epithelial cells were prepared to provide material for use in the diagnosis or treatment of prostatic cancer.

MATERIALS AND METHODS

Mice were immunized with LNCaP cell membranes followed by purified PSMA before fusion. Hybridomas were screened by reactivity with purified PSMA. Resulting antibodies were characterized by enzyme-linked immunosorbent assay, Western blot and fluorescence-activated cell sorter analyses.

RESULTS

Monoclonal antibody producing hybridomas designated 3E11, 3C2, 4E10-1.14, 3C9 and 1G3 were obtained which displayed specificities for differing regions of the extracellular domain of the PSMA protein. These antibodies reacted strongly with PSMA from multiple sources and specifically stained unfixed PSMA expressing cells by flow cytometric analysis.

CONCLUSIONS

The antibodies obtained displayed strong reactivity and specificity for extracellular epitopes of PSMA. These antibodies will have value in future diagnostic and therapeutic applications focusing on PSMA as a target antigen.

The National Cancer Data Base report on prostate carcinoma after the peak in incidence rates in the U.S. The American College of Surgeons Commission on Cancer and the American Cancer Society

BACKGROUND

Prostate carcinoma incidence has been declining since 1992 after a period of marked increase. Recent data from the National Cancer Data Base (NCDB) were examined to assess changes in prostate carcinoma patient characteristics and disease and treatment patterns coincidental to this decline. The NCDB is a program of the American College of Surgeons Commission on Cancer and the American Cancer Society that collects timely data from institutions representing every level of cancer care.

METHODS

Data from 1114 hospitals regarding 103,979 patients diagnosed with prostate carcinoma in 1992 and from 1144 hospitals regarding 72,337 patients diagnosed in 1995 were studied. Patient and disease characteristics studied included age, race, American Joint Committee on Cancer stage, and tumor histologic grade. Trends in treatment and variations in treatment by region also were examined.

RESULTS

The average age at diagnosis declined by 2 years over the period studied and the proportion of patients identified as African-American increased from 8.8% to 11.8%. The proportion of patients diagnosed with localized disease and the proportion of tumors of moderately differentiated histologic grade increased. The overall proportion of patients treated by radical prostatectomy increased and the use of external beam radiation treatment decreased. Substantial regional variation in treatment patterns was observed. The Pacific and Mountain state regions of the U. S. had the highest proportions of patients treated by radical prostatectomy although increases were occurring in other regions. Use of external beam radiation treatment was highest in the Northeast and Southeast states and was declining in the majority of regions. Use of brachytherapy radiation treatment by implantation of radioactive seeds was infrequent but increasing.

CONCLUSIONS

Comparison of the basic characteristics of prostate carcinoma data from 1992 and 1995 shows that patients are being diagnosed at younger ages and earlier stages, the proportion of African-Americans has increased, and more patients are being treated for cure. Regional differences in patterns of care persist but may be moderating. The annual prostate carcinoma death rate in the U.S. has declined an average of 1% per year since 1990.

CXCR-4, a chemokine receptor, is overexpressed in and required for proliferation of glioblastoma tumor cells

BACKGROUND AND OBJECTIVES

Using the technique of differential hybridization of Atlas Human cDNA expression arrays, we previously reported the isolation of a G protein coupled receptor, CXCR-4, which is overexpressed in glioblastoma multiforme tumor tissue (GMTT) compared to normal brain tissue (NBT).

METHODS

Using gene specific reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ hybridization, we studied its expression in a variety of brain and breast tumor tissue samples. To demonstrate the requirement of CXCR-4 in glioblastoma cell proliferation an antisense construct was overexpressed. Glioblastoma cells were also treated with antibodies against CXCR-4 and its ligand, SDFbeta-1.

RESULTS

Expression analysis indicated that CXCR-4 is overexpressed in 57% of the primary glioblastoma tissues and in 88% of the glioblastoma cell lines analyzed. Overexpression of CXCR-4 in glioblastoma cell lines enhanced their soft agar colony-forming capability. Expression of anti-sense CXCR-4 in glioblastoma cell lines caused neurite outgrowth and cellular differentiation. Treatment of glioblastoma cell lines with CXCR-4 and SDFbeta-1 specific antibodies caused inhibition of glioblastoma cell proliferation.

CONCLUSIONS

On the basis of these results, we conclude that CXCR-4 gene is required for the proliferation of human glioblastoma tumors.

Prostate-specific membrane antigen expression is greatest in prostate adenocarcinoma and lymph node metastases

OBJECTIVES

Prostate-specific membrane antigen (PSMA) is an integral membrane protein highly specific for the prostate. PSMA may be clinically useful for predicting outcome in patients with prostate cancer. We compared the expression of PSMA in prostate adenocarcinoma and lymph node metastases in a large series of patients with node-positive cancer.

METHODS

We studied 232 patients with node-positive adenocarcinoma who underwent bilateral pelvic lymphadenectomy and radical retropubic prostatectomy at the Mayo Clinic between 1987 and 1992. Immunohistochemistry was performed using monoclonal antibody 7E11-5.3 directed against PSMA. For each case, the percentage of immunoreactive cells in benign prostate tissue, adenocarcinoma, and lymph node metastases was estimated in 10% increments. Intensity was recorded using a scale of 0 to 3 (0 = no staining, 3 = highest).

RESULTS

Cytoplasmic immunoreactivity for PSMA was observed in all cases in benign epithelium and cancer, and most lymph node metastases. The number of cells stained was lowest in benign epithelium; cancer and lymph node metastases were similar (46.2% +/- 27.5% versus 79.3% +/- 18.5% versus 76.4% +/- 26.1%, respectively; all pairs P < 0.05). Intensity of staining was greatest in primary cancer and lowest in lymph node metastases.

CONCLUSIONS

PSMA is expressed in benign prostatic epithelium and primary cancer in all cases and in 98% of cases with lymph node metastases. Expression of PSMA was greatest in primary cancer for both percentage and intensity of immunoreactive cells. PSMA expression allows the identification of benign and malignant prostatic epithelium and may be a potentially valuable marker in the treatment of patients with prostate cancer.

Method for identifying prostate cells in semen using flow cytometry

BACKGROUND

Prostate-specific antigen (PSA) cannot differentiate benign prostatic hyperplasia (BPH), from prostatitis, or prostate cancer in the range of 4.0-10 ng/ml. An accurate cytologic or histologic assessment is necessary to confirm the proper diagnosis. The nature of a biopsy tends to make it a selective test not frequently repeated. We are reporting a technique employing semen as a source for the differential diagnosis of prostate epithelial cells.

METHODS

Eleven vasectomized and nonvasectomized prostate cancer patients provided semen samples (stage T1 to T2). Two patients provided repeat samples. In addition, 15 vasectomized or nonvasectomized individuals without evidence of disease provided semen samples. Three million cells fixed with 50% ethanol were stained by an antibody (7E11.C5) to prostate-specific membrane antigen (PSMA), Hybritech Antibody (399) to PSA, and cytokeratin 8 and 18. In addition to the antibodies described, a DNA stain To-Pro 3 was used to identify 2n-4n DNA containing cells. A dual laser, Becton Dickinson FACSCaliber cytometer, was used to analyze the samples.

RESULTS

All semen specimens contained diploid, cytokeratin 18-positive epithelial cells regardless of disease status. A clear difference between prostate cancer and normal prostate cell samples was observed using staining with 7E11.C5. The ratio of prostatic cells in the total epithelial cell population (PSMA:cytokeratin ratios) was calculated for each specimen. A retrospective study of sixteen semen samples from 11 prostate cancer patients had a mean PSMA:cytokeratin ratio of 0.57, whereas the samples from 15 patients without evidence of cancer had a mean PSMA:cytokeratin ratio of 0.11. This difference was significant. PSA staining was variable and inconsistent.

CONCLUSIONS

This report demonstrates that human semen contains prostate cells that can be characterized and used in the clinical diagnosis of prostate cancer.

Evaluation of phase I/II clinical trials in prostate cancer with dendritic cells and PSMA peptides

BACKGROUND

A phase I trial involving patients with advanced prostate cancer was conducted to assess the safe administration of dendritic cells (DC) and HLA-A0201-specific prostate-specific membrane antigen (PSMA) peptides (PSM-P1 or -P2). Thirty-three of the phase I participants were subsequently enrolled in a phase II trial, which involved six infusions of DC pulsed with PSM-P1 and -P2 peptides.

METHODS

Clinical monitoring was conducted up to 770 days from the start of the phase I study. Data collected included: complete blood count, bone and total alkaline phosphatase, prostate markers, physical examination, performance status, bone scan, ProstaScint scan, and chest X-ray, as well as assays to monitor cellular immune responses.

RESULTS

Nine partial responders were identified in the phase II study based on National Prostate Cancer Project (NPCP) criteria, plus 50% reduction of prostate-specific antigen. Four of the partial responders were also responders in the phase I study, with an average response duration of 225 days. Their combined average total response period was over 370 days. Five other responders were nonresponders in the phase I study. Their average partial response period was 196 days.

CONCLUSIONS

The responses observed in the phase I and II clinical trials were significant and of long duration. The partial-responder group included patients who continued to respond from phase I, as well as those who started to respond during the phase II trial.

Prostate specific membrane antigen expression in prostatic intraepithelial neoplasia and adenocarcinoma: a study of 184 cases

BACKGROUND

Prostate specific membrane antigen (PSM) is a membrane-bound antigen that is highly specific for benign and malignant prostate epithelial cells. Its expression in high grade prostatic intraepithelial neoplasia (PIN) has not been compared with that in prostate carcinoma.

METHODS

The authors performed an immunohistochemical study of representative sections from 184 radical prostatectomies from previously untreated patients with pathologic stage T2N0M0 adenocarcinoma treated at the Mayo Clinic between 1987 and 1991. Affinity-purified monoclonal antibody 7E11-5.3 directed against PSM was employed at a concentration of 20 microg/mL overnight. For comparison, serial sections in each case were stained with prostate specific antigen (PSA). Staining for all antibodies was performed using the streptavidin-biotin method. For each case, the percentage of immunoreactive cells in benign epithelium, PIN, and adenocarcinoma was estimated in increments of 10%. Cox proportional hazards models were used to identify the risk of carcinoma recurrence according to the number of immunoreactive PIN or cancer cells for PSM and PSA; the date of radical prostatectomy was used as the starting time, and serum PSA (biochemical) failure or clinical failure was the event. PSA biochemical failure was defined as serum PSA > 0.2 ng/mL at least 30 days after surgery.

RESULTS

Intense cytoplasmic immunoreactivity for PSM was observed in the benign and neoplastic epithelial cells in all cases (100% of cases staining). The number of cells staining was lower in benign epithelium and PIN than in adenocarcinoma (69.5+/-17.3% [range, 20-90%] vs. 77.9+/-13.2% [range, 30-100%] vs. 80.2+/-13.7% [range, 30-100%], respectively). With rare exceptions, basal cells were negative, and there was no immunoreactivity of the prostate stroma, urothelium, or vasculature. Adenocarcinoma gave the most intense and extensive staining, and the highest grades of adenocarcinoma (Gleason primary patterns 4 and 5) showed staining in virtually every cell; there was greater heterogeneity of staining in lower grades of adenocarcinoma. By contrast, PSA immunoreactivity was more intense and extensive in benign epithelium than in PIN and adenocarcinoma. The number of immunoreactive PIN or cancer cells for PSM and PSA was not predictive of PSA biochemical or clinical failure as defined in this study.

CONCLUSIONS

PSM was expressed in all cases of prostate adenocarcinoma, with the greatest extent and intensity observed in the highest grades. The expression increased incrementally from benign epithelium to high grade PIN or adenocarcinoma. Conversely, PSA showed the greatest staining in benign epithelium, with decreased expression incrementally from benign epithelium to high grade PIN or adenocarcinoma. Expression of PSM is clinically useful for the identification of prostate epithelium, particularly PIN or adenocarcinoma, and its expression is regulated independent of PSA. The number of PSM immunoreactive cells was not predictive of recurrence, most likely because of the presence of abundant immunoreactivity in most cases, or because of differential expression in primary and metastatic disease.

Prostate specific membrane antigen expression in prostatic intraepithelial neoplasia and adenocarcinoma: a study of 184 cases

BACKGROUND

Prostate specific membrane antigen (PSM) is a membrane-bound antigen that is highly specific for benign and malignant prostate epithelial cells. Its expression in high grade prostatic intraepithelial neoplasia (PIN) has not been compared with that in prostate carcinoma.

METHODS

The authors performed an immunohistochemical study of representative sections from 184 radical prostatectomies from previously untreated patients with pathologic stage T2N0M0 adenocarcinoma treated at the Mayo Clinic between 1987 and 1991. Affinity-purified monoclonal antibody 7E11-5.3 directed against PSM was employed at a concentration of 20 microg/mL overnight. For comparison, serial sections in each case were stained with prostate specific antigen (PSA). Staining for all antibodies was performed using the streptavidin-biotin method. For each case, the percentage of immunoreactive cells in benign epithelium, PIN, and adenocarcinoma was estimated in increments of 10%. Cox proportional hazards models were used to identify the risk of carcinoma recurrence according to the number of immunoreactive PIN or cancer cells for PSM and PSA; the date of radical prostatectomy was used as the starting time, and serum PSA (biochemical) failure or clinical failure was the event. PSA biochemical failure was defined as serum PSA > 0.2 ng/mL at least 30 days after surgery.

RESULTS

Intense cytoplasmic immunoreactivity for PSM was observed in the benign and neoplastic epithelial cells in all cases (100% of cases staining). The number of cells staining was lower in benign epithelium and PIN than in adenocarcinoma (69.5+/-17.3% [range, 20-90%] vs. 77.9+/-13.2% [range, 30-100%] vs. 80.2+/-13.7% [range, 30-100%], respectively). With rare exceptions, basal cells were negative, and there was no immunoreactivity of the prostate stroma, urothelium, or vasculature. Adenocarcinoma gave the most intense and extensive staining, and the highest grades of adenocarcinoma (Gleason primary patterns 4 and 5) showed staining in virtually every cell; there was greater heterogeneity of staining in lower grades of adenocarcinoma. By contrast, PSA immunoreactivity was more intense and extensive in benign epithelium than in PIN and adenocarcinoma. The number of immunoreactive PIN or cancer cells for PSM and PSA was not predictive of PSA biochemical or clinical failure as defined in this study.

CONCLUSIONS

PSM was expressed in all cases of prostate adenocarcinoma, with the greatest extent and intensity observed in the highest grades. The expression increased incrementally from benign epithelium to high grade PIN or adenocarcinoma. Conversely, PSA showed the greatest staining in benign epithelium, with decreased expression incrementally from benign epithelium to high grade PIN or adenocarcinoma. Expression of PSM is clinically useful for the identification of prostate epithelium, particularly PIN or adenocarcinoma, and its expression is regulated independent of PSA. The number of PSM immunoreactive cells was not predictive of recurrence, most likely because of the presence of abundant immunoreactivity in most cases, or because of differential expression in primary and metastatic disease.