Prostate-specific membrane antigen (PSMA) is a type II integral membrane glycoprotein, specifically expressed in prostatic epithelial cells and strongly upregulated in prostate cancer. PSMA is also present in the neovasculature of other solid tumors. These findings have spurred the development of PSMA-targeted therapies for prostate cancer, including immunotherapy, radioimmunotherapy, chemotherapy and gene therapy, and initiated the clinical trials of the first-generation products. However, general clinical application of these therapies still requires extensive clinical studies to test their clinical safety, stability and efficacy.
Antigens, Surface ; Genetic Therapy ; Glutamate Carboxypeptidase II ; Humans ; Immunotherapy ; Male ; Prostatic Neoplasms ; drug therapy ; therapy ; Radioimmunotherapy

OBJECTIVETo study the correlation of prostate-specific membrane antigen (PSMA) and prostate-specific antigen (PSA) expression with Gleason score of prostate carcinoma.

METHODSMonoclonal antibodies against epitopes of PSMA extracellular domain were prepared, with which the expression of PSMA of prostate carcinoma (PC) was determined by immunohistochemical staining. Correlation of its expression with Gleason score of PC was statistically analyzed, and compared with that of PSA.

RESULTSEight hybridoma cell lines secreting monoclonal antibodies specific for PSMA were prepared. PSMA expression level was positively correlated with Gleason score. In poorly differentiated prostate carcinoma, the expression intensity of PSMA was higher than that of medium-and well-differentiated prostate carcinoma (P < 0.01). However, there was no correlation between level of PSA expression and Gleason score (P > 0.05).

CONCLUSIONPSMA expression level may be used as a useful surrogate marker in Gleason grading of prostate carcinoma. It may be a more suitable target than PSA in antibody mediated immunotherapy against poorly differentiated prostate carcinoma which is usually not sensitive to hormonal therapy.

Antigens, Surface ; metabolism ; Biomarkers, Tumor ; metabolism ; Glutamate Carboxypeptidase II ; metabolism ; Humans ; Male ; Prostate-Specific Antigen ; metabolism ; Prostatic Neoplasms ; metabolism ; pathology

Antigens, Surface ; blood ; Diagnosis, Differential ; Glutamate Carboxypeptidase II ; blood ; Humans ; Male ; Neoplasm Staging ; Prostate-Specific Antigen ; blood ; Prostatic Hyperplasia ; pathology ; Prostatic Neoplasms ; etiology ; metabolism ; pathology ; Racemases and Epimerases ; analysis

Objective: To investigate the safety and effectiveness of radical retropubic prostatectomy (RRP) with adjuvant androgen deprivation or external radiotherapy in the treatment of prostate cancer (PCa) with pelvic lymph node metastasis (PLNM). METHODS: Twenty PCa patients underwent bilateral pedal lymphangiography (PLG) preoperatively, and 11 of them received lymph node aspiration for examination of the mRNA expressions of prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) in the lymph fluid by real-time RT-PCR. All the patients were treated by RRP with extended dissection of pelvic lymph nodes, and 3 of them by external radiotherapy in addition after recovery from urinary incontinence because of positive surgical margins, followed by adjuvant androgen deprivation therapy. RESULTS: Real-time RT-PCR showed positive mRNA expressions of PSA and PSMA in the lymph fluid of the 11 patients, all pathologically confirmed with PLNM. The median intraoperative blood loss was 575 ml, with blood transfusion for 5 cases. Positive surgical margin was found in 3 cases, lymphorrhagia in 2 and urinary leakage in another 2 each. There were no such severe complications as vascular injury and rectum perforation. The patients were followed up for 6－48 (mean 42) months, during which, biochemical recurrence was observed in 12 cases at a median of 12 months postoperatively and 2 patients died at 12 and 48 months respectively. CONCLUSIONS Bilateral PLG and lymph node aspiration for examination of the mRNA expressions of PSA and PSMA in the lymph fluid help to confirm PLNM preoperatively. Radical retropubic prostatectomy with adjuvant androgen deprivation or external radiotherapy is safe and effective for the treatment of PCa with PLNM, but it should be chosen cautiously for those with Gleason 5+5.
Androgen Antagonists ; therapeutic use ; Antigens, Surface ; metabolism ; Chemotherapy, Adjuvant ; Glutamate Carboxypeptidase II ; metabolism ; Humans ; Lymph Node Excision ; Lymph Nodes ; pathology ; Lymphatic Metastasis ; Male ; Pelvis ; Postoperative Period ; Prostate-Specific Antigen ; metabolism ; Prostatectomy ; methods ; Prostatic Neoplasms ; drug therapy ; metabolism ; surgery

BACKGROUNDProstate specific membrane antigen (PSMA) can facilitate the growth, migration, and invasion of the LNCaP prostate cancer cell lines, but the underlying molecular mechanisms have not yet been clearly defined. Here, we investigated whether PSMA serves as a novel regulator of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling by employing PSMA knockdown model and PI3K pharmacological inhibitor (LY294002) in LNCaP prostate cancer cells.

METHODSPSMA knockdown had been stably established by transfecting with lentivirus-mediated siRNA in our previous study. Then, LNCaP cells were divided into interference, non-interference, and blank groups. We first testified the efficacy of PSMA knockdown in our LNCaP cell line. Then, we compared the expression of PSMA and total/activated Akt by Western blotting in the above three groups with or without LY294002 treatment. Furthermore, immunocytochemistry was performed to confirm the changes of activated Akt (p-Akt, Ser473) in groups. Besides, cell proliferation, migration, and cell cycle were measured by CCK-8 assay, Transwell analysis, and Flow cytometry respectively.

RESULTSAfter PSMA knockdown, the level of p-Akt (Ser473) but not of total-Akt (Akt1/2) was significantly decreased when compared with the non-interference and blank groups. However, LY294002 administration significantly reduced the expression of p-Akt (Ser473) in all the three groups. The results of immunocytochemistry further confirmed that PSMA knockdown or LY294002 treatment was associated with p-Akt (Ser473) down-regulation. Decrease of cell proliferation, migration, and survival were also observed upon PSMA knockdown and LY294002 treatment.

CONCLUSIONSTaken together, our results reveal that PI3K/Akt signaling pathway inhibition may serve as a novel molecular mechanism in LNCaP prostate cancer cells of PSMA knockdown and suggest that Akt (Ser473) may play a critical role as a downstream signaling target effector of PSMA in this cellular model.

Antigens, Surface ; genetics ; metabolism ; Cell Line, Tumor ; Glutamate Carboxypeptidase II ; genetics ; metabolism ; Humans ; Male ; Phosphatidylinositol 3-Kinases ; metabolism ; Prostatic Neoplasms ; enzymology ; genetics ; therapy ; Proto-Oncogene Proteins c-akt ; metabolism ; RNA Interference ; Signal Transduction ; genetics ; physiology

OBJECTIVETo find sensitive and specific micro-metastic markers for prostate cancer.

METHODSUsing nested reverse transcription-PCR, we examined the expression of PSA, hK2 and PSMA mRNA in peripheral blood mononuclear cells of 51 patients with prostate cancer, 33 patients with benign prostate hyperplasia (BPH) and 32 normal young people.

RESULTSThe expression rates of PSA, hK2 and PSMA mRNA were 52.9%, 43.1% and 64.7%, respectively in prostate cancer group, and 6.2%, 7.7% and 4.6%, respectively in control group (BPH patients and normal young people) with statistical significance (P < 0.01). Although the expression rate of PSA and hK2 mRNA increased with cancer progression, there was no statistical significance among patients in different stages. The expression rate of PSMA mRNA was higher than that of PSA and hK2 mRNA in each clinical stage.

CONCLUSIONPSMA mRNA expression detected by nested RT-PCR is of greater value for the diagnosis, therapy choice and prognostic evaluation of prostate cancer patients.

Aged ; Antigens, Surface ; blood ; Biomarkers, Tumor ; blood ; Glutamate Carboxypeptidase II ; blood ; Humans ; Male ; Middle Aged ; Neoplasm Invasiveness ; Neoplasm Staging ; Prostate-Specific Antigen ; blood ; Prostatic Hyperplasia ; blood ; pathology ; Prostatic Neoplasms ; blood ; pathology ; Tissue Kallikreins ; blood

OBJECTIVETo detect and compare the transcriptional activities of prostate-specific membrane antigen (PSMA) promoter and enhancer and survivin promoter in different human prostate cancer cell lines, and to search for some evidence for the targeting gene therapy of human prostate cancer.

METHODSThe fragments of the PSMA promoter and enhancer and survivin promoter were amplified by PCR and inserted into pGL3-Basic. The recombinant plasmids were transiently transfected into human prostate cancer cell lines and normal Chang liver cells, and, their transcriptional activities in various cells were determined by measuring the expression of luciferase.

RESULTSThe survivin promoter exhibited a higher transcriptional activity than PSMA promoter and enhancer in tumor cell lines, and the S2pro promoter showed the highest activity, reaching one third of that of the CMV promoter.

CONCLUSIONThe survivin promoter is highly activated in prostate cancer cell lines and may serve as a new tool for the transcriptional targeting gene therapy of prostate cancer.

Antigens, Surface ; genetics ; Cell Line, Tumor ; Glutamate Carboxypeptidase II ; genetics ; Humans ; Inhibitor of Apoptosis Proteins ; genetics ; Male ; Plasmids ; Promoter Regions, Genetic ; Prostatic Neoplasms ; genetics ; therapy ; Transcription Initiation Site ; Transcriptional Activation ; Transfection

Prostate-specific membrane antigen (PSMA), the research of which has flourished in recent years, is a specific prostate cancer marker. PSMA plays a more and more important role in the early diagnosis, gene treatment and prognosis of the disease course of prostate cancer. This review focuses on the progress in researches of the structure, function, expression traits and gene expression of the PSMA protein, prostate cancer radioimmunoimaging, DNA vaccines and suicide gene therapy based on PSMA, as well as the role of PSMA in the clinical diagnosis and treatment of prostate cancer.
Antigens, Surface ; genetics ; Gene Expression Regulation, Neoplastic ; Glutamate Carboxypeptidase II ; genetics ; Humans ; Male ; Prostate-Specific Antigen ; genetics ; Prostatic Neoplasms ; diagnosis ; genetics ; therapy ; RNA, Messenger ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction

OBJECTIVETo construct, express and purify human fusion proteins composed of a single-chain antibody fragment scFv that recognizes the prostate specific membrane antigen (PSMA) protein, Fdt, HA2 and tp, and to analyze the binding activity of the expressed fusion proteins.

METHODSThe fusion protein genes scFv, scFv-tp, and scFv-Fdt-HA2-tp were amplified by PCR, and the genes obtained were then cloned into the expression vector pET28 and expressed in E. coli BL21. The expressed products were identified by SDS-PAGE and Western blot and purified with Ni(2+)-NTA chelating agarose. The antigen-binding activity of the fusion proteins was determined by ELISA.

RESULTSThe human anti-PSMA fusion gene was successfully constructed and expressed in M15 as the inclusion body after induced with IPTG. All the target proteins expressed could bind the PSMA antigen.

CONCLUSIONFusion proteins can specifically bind the PSMA antigen. This finding contributes to the study of the targeted delivery of siRNA.

Antigens, Surface ; immunology ; Cloning, Molecular ; Electrophoresis, Polyacrylamide Gel ; Escherichia coli ; genetics ; immunology ; Glutamate Carboxypeptidase II ; immunology ; Humans ; Male ; Polymerase Chain Reaction ; RNA, Small Interfering ; administration & dosage ; immunology ; Recombinant Fusion Proteins ; genetics ; immunology ; Single-Chain Antibodies ; genetics ; immunology

We investigated whether the detection of prostate specific membrane antigen (PSMA) in blood preoperatively has predictive value for biochemical recurrence (BCR) after radical prostatectomy in patients with prostate cancer. All 134 patients scheduled to receive radical prostatectomy for prostate cancer were prospectively enrolled. The authors used nested reverse transcriptase-polymerase chain reaction (RT-PCR) assay to detect PSMA mRNA-bearing cells in peripheral blood, and analyzed the ability of PSMA mRNA positivity to predict BCR after surgery. PSMA-mRNA was detected in 24 (17.9%) patients by RT-PCR. Over a median follow-up of 20 months (range, 3 to 46 months), BCR developed in 15 patients (11.2%) and median time to BCR was 7 months (range, 3 to 25 months). Kaplan-Meier analysis revealed a significant difference between those positive or negative for PSMA in terms of recurrence-free actuarial probability (log rank P=0.0039). Multivariate analysis showed that positivity for PSMA mRNA (HR: 3.697, 95% CI 1.285-10.634, P=0.015) and a biopsy Gleason score of > or =7 (HR: 4.500, 95% CI 1.419-14.274, P=0.011) were independent preoperative predictors of BCR. The presence of PSMA mRNA in peripheral blood can be used to predict BCR after radical prostatectomy.
Aged ; Antigens, Surface/*blood/genetics ; Glutamate Carboxypeptidase II/*blood/genetics ; Humans ; Male ; Middle Aged ; Neoplasm Recurrence, Local/blood/*diagnosis ; Predictive Value of Tests ; *Prostatectomy ; Prostatic Neoplasms/blood/*diagnosis/surgery ; RNA, Messenger/*blood ; Reverse Transcriptase Polymerase Chain Reaction ; Severity of Illness Index ; Time Factors