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ABSTRACT: Androgen deprivation therapy has been the major treatment for advanced prostate cancer (PCa) and has shown to prolong life. However, remissions are temporary and patients almost inevitably progress to become castration-resistant prostate cancer (CRPC). CRPC is almost incurable even when treated with docetaxel that may have a slight life prolonging effect on CRPC patients. Interestingly, most of CRPC still express androgen receptor (AR) and depend on the AR for growth. Recently it has been suggested that AR may act as a tumor suppressor in normal prostatic epithelial cells, while in PCa cells AR becomes oncogenic, even under androgen deprivation states. The mechanisms for the latter are still under intensive investigations. A number of studies showed that, in fact, AR signaling is increased under an androgen-depleted environment. The mechanisms suggested in these studies including AR mutations, AR overexpression by gene amplification and other mechanisms that allow activation by low androgen levels or by other endogenous steroids, increased local de novo synthesis of androgens will be discussed. Moreover, developments and tests in clinical trials in CRPC of a number of novel agents interrupting AR signaling mediated PCa growth will also be discussed.
Current cancer drug targets 06/2010; 10(4):402-10. · 5.13 Impact Factor
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ABSTRACT: Radioiodine therapy, the most effective form of systemic radiotherapy available, is currently useful only for thyroid cancer because of thyroid-specific expression of the sodium iodide symporter (NIS). Here we explore the efficacy of a novel form of gene therapy using adenovirus-mediated in vivo NIS gene transfer followed by (131)I administration for treatment of prostate cancer. Prostate cancer xenografts in nude mice injected with an adenovirus carrying the NIS gene linked to the cytomegalovirus (CMV) promoter revealed highly active uptake of radioiodine. Following administration of 3 mCi of (131)I, we observed an average tumor volume reduction of 84 +/- 12%. These results show for the first time that in vivo NIS gene delivery into non-thyroidal tumors is capable of inducing accumulation of therapeutically effective radioiodine doses and might therefore represent an effective and potentially curative therapy for prostate cancer.
Gene Therapy 11/2001; 8(20):1524-31. · 3.71 Impact Factor
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ABSTRACT: A number of reports have shown that the polyphenolic flavonoid silymarin (SM) is an effective anticancer agent. Agents with novel mechanisms of blocking androgen receptor (AR) function may be useful for prostate cancer prevention and therapy. Previous studies showed that silibinin (SB), the major active component of SM, could inhibit cell proliferation of a human prostate cancer cell line, LNCaP, by arresting the cell cycle at the G(1) phase without causing cell death. This study further delineates the potential molecular mechanism by which SM and SB exhibit antiproliferative effects on androgen-responsive prostate cancer cells by inhibiting function of the AR. We observed that SM and SB inhibited androgen-stimulated cell proliferation as well as androgen-stimulated secretion of both prostate-specific antigen (PSA) and human glandular kallikrein (hK2). Additionally, for the first time, we show that an immunophilin, FKBP51, is androgen regulated and that this up-regulation is suppressed by SM and SB. We further demonstrate that transactivation activity of the AR was diminished by SM and SB using gene transfer of PSA promoter and hK2 androgen-responsive element constructs. However, expression and steroid-binding ability of total AR were not affected by SM in western blotting and ligand-binding assays. Intriguingly, we found that nuclear AR levels are significantly reduced by SM and SB in the presence of androgens using western blotting assay and immunocytochemical staining. This study provides a new insight into how SM and SB negatively modulate androgen action in prostate cancer cells.
Carcinogenesis 10/2001; 22(9):1399-403. · 5.70 Impact Factor
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ABSTRACT: There is some epidemiological support for a protective influence of omega-3 fatty acids against prostate cancer. We wanted to explore whether omega-3 polyunsaturated fatty acids such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) can affect androgen receptor function in prostate cancer cells. Our study showed that both DHA and EPA inhibit androgen-stimulated cell growth. Androgenic induction of prostate-specific antigen (PSA) protein was repressed by DHA and EPA in a dose-dependent manner. The mRNA levels of five androgen up-regulated genes, PSA, ornithine decarboxylase, NKX 3.1, immunophilin fkbp 51 and Drg-1, were decreased with DHA treatment in the presence of androgens. Transfection experiments using a DNA vector containing androgen-responsive elements demonstrated that both DHA and EPA could interfere with transactivation activities of the androgen receptor (AR). However, western blot analysis of AR protein showed that DHA and EPA treatments did not change AR expression levels. Interestingly, the proto-oncoprotein c-jun was increased by DHA treatment. A transient transfection found that forced expression of c-jun inhibited AR transactivation activity. Thus, this study found that the inhibitory effects of omega-3 polyunsaturated fatty acids on AR-mediated actions are due, at least in part, to an increase in c-jun protein.
Carcinogenesis 09/2001; 22(8):1201-6. · 5.70 Impact Factor
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ABSTRACT: Neuroendocrine (NE) differentiation may be related to the growth and progression of prostate cancer, especially androgen-insensitive tumors. Recently the over-expression of a new anti-apoptosis protein, survivin, has attracted attention for its potential implication in many human cancers. The fact that NE cells in prostate are bcl-2 negative prompted us to investigate if the prostatic NE cells over-express survivin.
Double immunohistochemical staining and immunofluorescence of chromogranin A (CgA) and survivin were performed in 57 patients with localized prostate cancer who underwent radical prostatectomy. The terminal deoxynucleotidyl transferase (TDT)-mediated dUTP-digoxigenin nick end-labeling (TUNEL) method was used for apoptosis detection in three prostate cancer specimens with NE differentiation. The relationship between NE differentiation and clinicopathological characteristics, disease progression as well as patient survival, were analyzed retrospectively.
It was found that NE cells in both benign and malignant prostate tissues over-expressed the anti-apoptosis protein survivin. While apoptosis was detected in non-NE epithelial cells, all NE cells were negative for apoptosis detection. During the period of follow-up, 17 (63%) of 27 patients with NE differentiation had prostate cancer progression, while 12 (40%) of 30 patients without NE differentiation had systemic prostate cancer progression. 10 (37%) of 27 patients with NE differentiation died from prostate cancer during the period of follow up, while 6 (20%) of 30 patients without NE differentiation died from prostate cancer. However, none of these characteristics reached statistical significance, probably because of the small number of cases enrolled.
This study discovers that all the prostatic NE cells express the new anti-apoptosis protein survivin. This provides a strong molecular basis for the hypothesis that NE cells may endure stressful conditions and escape from apoptosis. While our results suggest a trend of NE differentiation with poorer prognosis, the prognosis implication cannot be concluded due to our small sample size.
The Prostate 07/2001; 48(1):7-15. · 3.48 Impact Factor
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ABSTRACT: Tissue-specific transcriptional regulatory elements can increase the safety of gene therapy vectors. Unlike prostate-specific antigen (PSA/hK3), whose expression displays an inverse correlation with prostate cancer grade and stage, human glandular kallikrein 2 (hK2) is upregulated in higher grade and stage disease. Therefore, our goal was to develop a strong and prostate-specific hK2-based promoter for targeted gene therapy. We identified the minimum "full-strength" hK2 enhancer and built transcriptional regulatory elements composed of multiple tandem copies of this 1.2-kb enhancer, fused to the hK2 minimal promoter. Relative to the weak induction of the minimal hK2 promoter by androgen analog (R1881) in androgen receptor (AR)-positive LNCaP cells, transcriptional activity was increased by 25-, 44-, 81-, and 114-fold when one to four enhancers were spliced to the hK2 promoter, respectively. In contrast, the enhancer/promoter elements were inactive in the AR(-) prostate cancer line PC-3 and in a panel of nonprostate lines, including 293, U87, MCF-7, HuH-7, and HeLa cells. Furthermore, we generated a recombinant adenovirus, ADV.hK2-E3/P-EGFP, expressing enhanced green fluorescent protein (EGFP) under the control of the hK2 triplicate enhancer/promoter, and compared its properties with ADV.CMV-EGFP expressing EGFP under the control of the cytomegalovirus (CMV) enhancer/promoter. Unlike the CMV promoter, the hK2-E3/P promoter was at least 100-fold inducible by R1881 in the adenoviral backbone. Compared with in situ injection of subcutaneous LNCaP tumors with ADV.CMV-EGFP, which led to detectable EGFP expression in tumor, liver, and brain tissue, ADV.hK2-E3/P-EGFP injection led to robust but tumor-restricted EGFP expression. These results suggest that the hk2 multienhancer/promoter should be a powerful novel reagent for safer targeted gene therapy of prostate cancer.
Human Gene Therapy 04/2001; 12(5):549-61. · 4.22 Impact Factor
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ABSTRACT: The androgen receptor (AR) is involved in the development and progression of prostate cancer. In order to find new compounds that may present novel mechanisms to attenuate the function of AR, we investigated the effect of a natural flavonoid chemical, quercetin, on androgen action in an androgen-responsive LNCaP prostate cancer cell line. Western blot analysis showed that AR protein expression was inhibited by quercetin in a dose-dependent manner. To demonstrate that the repression effects on AR expression can actually reduce its function, we found that quercetin inhibited the secretion of the prostate-specific, androgen-regulated tumor markers, PSA and hK2. The mRNA levels of androgen-regulated genes such as PSA, NKX3.1 as well as ornithine decarboxylase (ODC) were down-regulated by quercetin. Transient transfections further showed that quercetin inhibited AR-mediated PSA expression at the transcription level. Finally, it was demonstrated that quercetin could repress the expression of the AR gene at the transcription level. Our result suggests that quercetin can attenuate the function of AR by repressing its expression and has the potential to become a chemopreventive and/or chemotherapeutic agent for prostate cancer.
Carcinogenesis 04/2001; 22(3):409-14. · 5.70 Impact Factor
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ABSTRACT: We developed a highly sensitive splice variant-specific reverse transcriptase-PCR (RT-PCR) assay for human glandular kallikrein (hK2) mRNA and tested its ability to detect metastatic disease in men with clinically localized prostate cancer. An RT-PCR assay using primers spanning intron IV and including a significant portion of the 3' untranslated region of the hKLK2 gene, with maximum nonhomology to both hK1 and hK3, was developed. The limit of detection of the assay was five copies of hK2 cDNA and one LNCaP cell in 10(9) lymphoblasts. RT-PCR-hK2 was performed on preoperative peripheral blood specimens from 228 consecutive radical prostatectomy patients as well as 7 metastatic prostate cancer patients and 14 healthy men without prostate cancer. This new RT-PCR-hK2 assay amplifies two distinct fragments. The larger fragment (hK2-U) is approximately 680 bp in length and corresponds to the amplified product of a previously reported splice variant in the splice donor site of intron IV in the hKLK2 gene. The smaller fragment (hK2-L) is approximately 643 bp in length and corresponds to the amplified product of the native hK2 mRNA. Whereas the RT-PCR-hK2-L assay was positive in 71% of our patients with metastatic prostate cancer, 14% of healthy control men also tested positive. By univariate (P = 0.028) and multivariate (P = 0.0269) analysis, which controlled for preoperative PSA, clinical stage, and biopsy Gleason score, RT-PCR-hK2-L status added prognostic information to the prediction of lymph node-positive disease. We have developed a new RT-PCR assay which demonstrates a high sensitivity for detecting hK2 mRNA. Preoperative RT-PCR-hK2-L status helps predict pathological lymph node positivity in patients with clinically localized prostate cancer.
Cancer Research 01/2001; 60(24):7142-8. · 7.86 Impact Factor
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ABSTRACT: Causing prostate cancer cells to express functionally active sodium iodide symporter (NIS) by targeted NIS gene transfer might offer the possibility of radioiodine therapy of prostate cancer. Therefore, we investigated radioiodine accumulation and therapeutic effectiveness of 131I in NIS-transfected prostate cancer cells in vitro and in vivo. The human prostatic adenocarcinoma cell line LNCaP was stably transfected with NIS cDNA under the control of the prostate-specific antigen promoter. The stably transfected LNCaP cell line NP-1 showed perchlorate-sensitive, androgen-dependent iodide uptake in vitro that resulted in selective killing of these cells by 131I in an in vitro clonogenic assay. Xenografts were established in athymic nude mice and imaged using a gamma camera after i.p. injection of 500 microCi of 123I. In contrast to the NIS-negative control tumors (P-1) which showed no in vivo uptake of 123I, NP-1 tumors accumulated 25-30% of the total 123I administered with a biological half-life of 45 h. In addition, NIS protein expression in LNCaP cell xenografts was confirmed by Western blot analysis and immunohistochemistry. After a single i.p. application of a therapeutic 131I dose (3 mCi), significant tumor reduction was achieved in NP-1 tumors in the therapy group compared with P-1 tumors and tumors in the control group. In conclusion, a therapeutic effect of 131I has been demonstrated in prostate cancer cells after induction of tissue-specific iodide uptake activity by prostate-specific antigen promoter-directed NIS expression in vitro and in vivo. This study demonstrates the potential of NIS as a novel therapeutic gene for nonthyroidal cancers, in particular prostate cancer.
Cancer Research 12/2000; 60(22):6526-30. · 7.86 Impact Factor
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ABSTRACT: Human glandular kallikrein (hK2) is an androgen regulated protein primarily expressed in the prostate and recently identified as a novel prostate cancer marker. A 5 kb 5' flanking region of the hK2 gene was isolated and sequenced to characterize the regulatory mechanisms for the expression of hK2 in the androgen responsive prostate cell line, LNCaP. Using gene transfer, gel shift, and mutagenesis assays we have identified an ARE in the 5' far upstream promoter region of the hK2 gene that is crucial for its regulation in LNCaP cells. This study further demonstrated that the hK2 upstream ARE plays a predominant role in androgenic response. More interestingly, previously identified AREs in the prostate specific antigen promoter and the hK2 proximal promoter exert little activity in LNCaP cells. This study for the first time identifies a unique ARE that alone mediates the function of the androgen receptor in LNCaP cells in a cell dependent manner. This study also examines the activity of this ARE with 1alpha, 25 dihydroxy-vitamin D3 on the expression of the hK2 gene in LNCaP cells.
Molecular and Cellular Endocrinology 11/2000; 168(1-2):89-99. · 4.19 Impact Factor
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ABSTRACT: The biological modifier delta12-prostaglandin J2 and related prostaglandins have been reported to have significant growth-inhibitory activity with induction of heat shock proteins (Hsps). Tumor-derived Hsps have been shown previously to elicit specific immunity to tumors from which they are isolated. In this study, 15-deoxy-delta12,14-prostaglandin J2 (15d-PGJ2)-induced Hsp70 was purified from transgenic adenocarcinoma mouse prostate cells (TRAMP-C2). It was then tested for its ability to activate specific CTLs and induce protective immunity against prostate cancer in C57BL/6 mice. Treatment of cells with 8.0 microM 15d-PGJ2 for 24 h caused significant induction of Hsp70 expression. The yield of Hsp70 purified from 15d-PGJ2-treated cells was 4-5-fold higher when compared with untreated TRAMP-C2 cells. Vaccination of mice with Hsps isolated from TRAMP-C2 cells elicited tumor-specific CTLs and prevented the growth of TRAMP-C2 tumors. These results indicate that the induced heat shock proteins may have promising applications for antitumor, T-cell immunotherapy. In particular, these findings have important implications for the development of novel anticancer therapies aimed at promoting an immune response to prostate tumors.
Cancer Research 10/2000; 60(17):4714-8. · 7.86 Impact Factor
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ABSTRACT: Androgens via their cognate receptor may be involved in the development and progression of prostate cancer. The aim of this study was to determine whether tea polyphenols have inhibitory effects on androgen action in an androgen-responsive, prostate cancer cell line, LNCaP. The tea polyphenol, EGCG, inhibited LNCaP cell growth and the expression of androgen regulated PSA and hK2 genes. Moreover, EGCG had a significant inhibitory effect on the androgenic inducibility of the PSA promoter. Immunoblotting detected a decrease in androgen receptor protein with treatments of the tea polyphenols EGCG, GCG and theaflavins. Northern blot analysis showed decreased levels of androgen receptor mRNA by EGCG. Transient transfections demonstrated that EGCG and theaflavins could repress the transcriptional activities of the androgen receptor promoter region. An Sp1 binding site in the androgen receptor gene promoter is an important regulatory component for its expression. This study suggests Sp1 is the target for the tea polyphenols because treatments of EGCG decreased the expression, DNA binding activity and transactivation activity of Sp1 protein. In conclusion, we have described a new property of tea polyphenols that inhibits androgen action by repressing the transcription of the androgen receptor gene.
Oncogene 05/2000; 19(15):1924-32. · 6.37 Impact Factor
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ABSTRACT: The recent demonstration of human glandular kallikrein (hK2) expression in a breast carcinoma cell line has suggested that this putatively prostate-restricted, steroid hormone-regulated protease may also be expressed in breast epithelium in vivo and secreted into the mammary duct system. Given that the only substrate yet identified for hK2 activity is the precursor of prostate-specific antigen (PSA), the expression of which in breast carcinomas may be associated with favourable prognosis, our purpose was to examine the expression pattern of both hK2 and PSA in breast tumour tissues. Cytosolic extracts of 336 primary breast carcinomas prepared for routine oestrogen receptor (ER) and progesterone receptor (PR) analysis, as well as 31 nipple aspirates from six women with non-diseased mammary glands, were assayed for hK2 and PSA using immunofluorometric assays developed by the authors. In the tumour extracts, measurable hK2 and PSA concentrations were detected in 53% and 73% of cases respectively, and were positively correlated to each other (r = 0.59, P = 0.0001). Higher concentrations of PSA and hK2 were found in tumours expressing steroid hormone receptors (P = 0.0001 for PSA and P = 0.0001 for hK2, by Wilcoxon tests for both ER and PR), and both PSA (r = 0.25, P = 0.0001) and hK2 (r = 0.22, P = 0.0001) correlated directly with PR levels. A negative correlation between patient age and PSA (r = -0.12, P = 0.03) was also found. Both proteins were present in nipple aspirate fluid at relatively high concentrations which were positively correlated (r = 0.53, P = 0.002). The molecular weights of the immunoreactive species quantified by the hK2 and PSA assays were established by high-performance liquid chromatography (HPLC) and were consistent with the known molecular weights of hK2 and PSA. Together these data provide the first evidence, to our knowledge, that both malignant breast tissue and normal breast secretion contain measurable quantities of hK2, and that the degree of hK2 expression or secretion is directly proportional to the expression of PSA and steroid hormone receptors. hK2 expression may therefore be a marker of steroid hormone action in breast tissue.
British Journal of Cancer 02/2000; 82(2):361-7. · 5.04 Impact Factor
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ABSTRACT: 15-Deoxy-delta12,14-prostaglandin J2 (15d-PGJ2) is a highly specific activator of the peroxisome proliferator-activated receptor gamma (PPAR-gamma). We investigated the effect of 15d-PGJ2 on three human prostate cancer cell lines, LNCaP, DU145, and PC-3. Western blotting demonstrated that PPAR-gamma1 is expressed predominantly in untreated prostate cancer cells. Treatment with 15d-PGJ2 caused an increase in the expression of PPAR-gamma2, whereas PPAR-gamma1 remained at basal levels. PPARs alpha and beta were not detected in these cells. Lack of lipid accumulation, increase in CCAAT/enhancer binding proteins (C/EBPs), or expression of aP2 mRNA indicated that adipocytic differentiation is not induced in these cells by 15d-PGJ2. 15d-PGJ2 and other PPAR-gamma activators induced cell death in all three cell lines at concentrations as low as 2.5 microM (similar to the Kd of PPAR-gamma for this ligand), coinciding with an accumulation of cells in the S-phase of the cell cycle. Activators for PPAR-alpha and beta did not induce cell death. Staining with trypan blue and propidium iodide suggested that, although the plasma membrane appears intact by electron microscopy, disturbances are evident as early as 2 h after treatment. Mitochondrial transmembrane potentials are significantly reduced by 15d-PGJ2 treatment. In addition, treatment with 15d-PGJ2 resulted in cytoplasmic changes, which are indicative of type 2 (autophagic), nonapoptotic programmed cell death.
Cell growth & differentiation: the molecular biology journal of the American Association for Cancer Research 02/2000; 11(1):49-61.
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ABSTRACT: Androgens via their receptor (AR) may play a role in prostate cancer etiology. This study focuses on the inhibitory effects of resveratrol on androgen action in the LNCaP prostate cancer cell line. We found that resveratrol represses different classes of androgen up-regulated genes at the protein or mRNA level including prostate-specific antigen, human glandular kallikrein-2, AR-specific coactivator ARA70, and the cyclin-dependent kinase inhibitor p21. This inhibition is likely attributable to a reduction in AR contents at the transcription level, inhibiting androgen-stimulated cell growth and gene expression. This study suggests that resveratrol may be a useful chemopreventive/chemotherapeutic agent for prostate cancer.
Cancer Research 01/2000; 59(23):5892-5. · 7.86 Impact Factor
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A W Partin,
W J Catalona,
J A Finlay,
C Darte,
D J Tindall, C Y Young,
G G Klee,
D W Chan,
H G Rittenhouse,
R L Wolfert,
D L Woodrum
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ABSTRACT: Human glandular kallikrein 2 (hK2) and prostate-specific antigen (PSA) are members of a multigene family of serine proteases that share approximately 80% sequence homology. Both are expressed in the prostate epithelium, are under androgen regulation, are present in serum and seminal fluid, and can form complexes with endogenous protease inhibitors (eg, alpha2-macroglobulin and alpha1-antichymotrypsin). Differences in immunohistochemistry and substrate specificity suggest hK2 may provide unique information for early detection and characterization of prostate cancer.
Nine hundred thirty-seven archived serum samples from men treated at two academic institutions were studied. All men underwent biopsy, had a histologically confirmed diagnosis of cancer or noncancer, and a total PSA level greater than 2 ng/mL. Samples were tested in Hybritech's Tandem-R PSA and Tandem-R free PSA (fPSA) assays and a research prototype assay for total hK2 (thK2).
The thK2/fPSA ratio provided additional specificity for cancer detection over PSA and the percentage of fPSA (%fPSA). A model for cancer detection using %fPSA and the thK2/fPSA ratio when PSA is 2 to 4 ng/mL is proposed that would identify as many as 40% of the cancers and would require biopsy in only 16.5% of the men in this PSA range.
In this study, %fPSA and thK2/fPSA provided unique information for prostate cancer detection and increased the specificity of cancer detection.
Urology 12/1999; 54(5):839-45. · 2.43 Impact Factor
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ABSTRACT: Nonsteroidal anti-inflammatory drugs (NSAIDs) play potential roles in chemoprevention of colon cancer and others by inhibiting prostaglandin synthesis. In this report, we used LNCaP cells, an androgen-responsive human prostate carcinoma cell line, to study the effects of two NSAIDs, flufenamic acid (FA) and piroxicam (PXM), on the cancer cell growth stimulated by androgens. We found that FA had much higher potency to inhibit LNCaP cell growth than PXM. FA dramatically reduced the expression of androgen inducible genes, such as prostate-specific antigen (PSA) and the homeo-domain transcription factor Nkx3.1, but PXM did not. In vitro transfection experiments showed that FA down regulated the PSA expression at the transcription level. Western and northern blot analyses demonstrated that FA inhibited the androgen receptor (AR) expression at mRNA and protein levels. Suppressed AR expression may be the cause of FA-mediated inhibition of the androgen inducible gene expression. Our data also showed that FA significantly reduced the AR promoter-mediated transcription activities. This study indicated that AR might be a target for FA to inhibit LNCaP cell growth. FA and other similar NSAIDs may be potential candidates for chemoprevention of human prostate cancer by modulating the expression of AR.
Endocrinology 12/1999; 140(11):5451-4. · 4.46 Impact Factor
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ABSTRACT: Human glandular kallikrein (hK2) is a serine protease that has 79% amino acid identity with prostate-specific antigen (PSA). Both free hK2 and hK2 complexed to alpha1-antichymotrypsin (ACT) are present in the blood in low concentrations. We wished to measure hK2 in serum with limited contribution from hK2-ACT for the results. Methods: We developed an automated assay for hK2 with use of a select pair of monoclonal antibodies. The prototype assay was implemented on a Beckman Coulter ACCESS(R) analyzer.
The detection limit of the assay was 1.5 ng/L, the "functional sensitivity" (day-to-day CV <15%) was <4 ng/L, cross-reactivity with PSA and PSA-ACT was negligible, and cross-reactivity with hK2-ACT was 2%. After surgical removal of prostate glands, serum hK2 was <7 ng/L and was <15 ng/L in most healthy women. The median serum concentration of hK2 in healthy men without prostate cancer was 26 ng/L. The median concentration of hK2 was 72 ng/L for men having prostate cancer with lower Gleason scores compared with 116 ng/L for men with more advanced cancer. The concentration of hK2 correlated weakly with PSA, with the mean hK2 concentrations generally 30- to 80-fold lower than PSA concentrations.
The availability of a robust, high sensitivity automated assay for hK2 should facilitate further investigations of the role of hK2 measurements in the management of patients with prostate disease.
Clinical Chemistry 07/1999; 45(6 Pt 1):800-6. · 7.91 Impact Factor
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ABSTRACT: To describe the expression of a potential new tumor marker, human glandular kallikrein 2 (hK2), in primary adenocarcinoma and lymph node metastases that may be useful as an adjunct to prostate-specific antigen (PSA) in the diagnosis and monitoring of prostate cancer.
We evaluated 151 radical prostatectomy specimens removed at Mayo Clinic with node-positive adenocarcinoma to compare cytoplasmic expression of hK2, pro-hK2, and PSA in benign tissue, prostate adenocarcinoma, and lymph node metastases. Monoclonal antibodies for mature hK2 (hK2-G586), pro-hK2 (pro-hK2-G464), and PSA (PSA-773) were used. A polyclonal antibody for PSA was also used. Immunoreactivity in each case was tested to determine whether cancer recurrence could be predicted.
Intense epithelial cytoplasmic immunoreactivity was observed in every case for hK2-G586, pro-hK2-G464, PSA-773, and polyclonal PSA (100% of cases, respectively). The intensity and extent of hK2 expression was greater in lymph node metastases than in primary cancer; furthermore, the expression in primary cancer was greater than in benign epithelium. Pro-hK2 was expressed in a greater percentage of cells in primary cancer than in benign tissue; furthermore, pro-hK2 was expressed to a greater extent in primary cancer than in lymph node metastases. In marked contrast to mature hK2, monoclonal PSA immunoreactivity was expressed to a higher extent in primary cancer than in lymph node metastases. Polyclonal PSA showed an incremental increase in expression from benign tissue to primary cancer and a further increase in expression in lymph node metastases.
hK2 was expressed in every cancer, and the expression incrementally increased from benign epithelium to primary cancer and lymph node metastases. Pro-hK2 was expressed to the greatest extent in primary cancer. Monoclonal PSA displayed inverse immunoreactivity compared with hK2. Polyclonal PSA showed incremental increases, suggesting that both hK2 and PSA were being detected. Tissue expression of hK2 appears to be regulated independently of PSA in benign epithelium, adenocarcinoma, and lymph node metastases.
Urology 06/1999; 53(5):939-44. · 2.43 Impact Factor
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ABSTRACT: Currently, no curative therapy for metastatic prostate cancer exists. Causing prostate cancer cells to express functionally active sodium iodide symporter (NIS) would enable those cells to concentrate iodide from plasma and might offer the ability to treat prostate cancer with radioiodine. Therefore, the aim of our study was to achieve tissue-specific expression of full-length human NIS (hNIS) cDNA in the androgen-sensitive human prostatic adenocarcinoma cell line LNCaP and in subcell lines C4, C4-2, and C4-2b in vitro. For this purpose, an expression vector was generated in which full-length hNIS cDNA coupled to the prostate-specific antigen (PSA) promoter has been ligated into the pEGFP-1 vector (NIS/PSA-pEGFP-1). The PSA promoter is responsible for androgen-dependent expression of PSA in benign and malignant prostate cells and was therefore used to mediate androgen-dependent prostate-specific expression of NIS. In addition, two control vectors were designed, which consist of the pEGFP-1 vector containing the PSA promoter without NIS cDNA (PSA-pEGFP-1) and NIS cDNA without the PSA promoter (NIS-pEGFP-1). Prostate cancer cells were transiently transfected with each of the above-described expression vectors, incubated with or without androgen (mibolerone) for 48 h, and monitored for iodide uptake activity. In addition, stably transfected LNCaP cell lines were established for each vector. Prostate cells transfected with NIS/PSA-pEGFP-1 showed perchlorate-sensitive, androgen-dependent iodide uptake in a range comparable to that observed in control cell lines transfected with hNIS cDNA. Perchlorate-sensitive iodide uptake was not observed in cells transfected with NIS/PSA-pEGFP-1 and treated without androgen or in cells transfected with the control vectors. In addition, prostate cancer cell lines without PSA expression (PC-3 and DU-145) did not show iodide uptake activity when transfected with NIS/PSA-pEGFP-1. Western blotting of LNCaP and C4-2b cell membranes transfected with NIS/PSA-pEGFP-1 using a monoclonal antibody that recognizes the COOH-terminus of hNIS revealed a band with a molecular weight of 90,000 that was not detected in androgen-deprived cells or in cells transfected with the control vectors, as well as a minor band at Mr 150,000 in transiently transfected LNCaP cell membranes. In conclusion, tissue-specific androgen-dependent iodide uptake activity has been induced in prostate cancer cells by PSA promoter-directed NIS expression. This study represents an initial step toward therapy of prostate cancer with radioiodine.
Cancer Research 06/1999; 59(9):2136-41. · 7.86 Impact Factor
