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H Klocker

Publications and source records attributed to H Klocker.

At least 73 records · Page 4Linked to original sources
PubMed1998

Analysis of a mutant androgen receptor offers a treatment modality in a patient with partial androgen insensitivity syndrome.

OBJECTIVES: In male pseudohermaphroditism patients, we have detected androgen receptor (AR) gene mutations as the underlying molecular defect. The properties of these mutant receptors regarding hormone binding and transactivation were characterized. In a newborn patient with partial androgen insensitivity syndrome caused by an AR gene point mutation, the functional analysis of the mutated AR offers a possible treatment modality. METHODS: Specific binding of dihydrotestosterone in the patient's genital skin fibroblasts, thermostability, and 5 alpha-reductase activity were evaluated. Furthermore, an AR gene mutation was detected by direct sequencing. The ability of the mutant receptor to activate androgen-responsive elements in the DNA was determined by recreating an AR expression vector and cotransfection experiments. RESULTS: The newborn patient with partial androgen insensitivity showed a qualitative and quantitative binding defect. A point mutation in the ligand binding domain was identified as the underlying cause. Transactivation assays demonstrated that increasing androgen concentration can restore the function of the mutated receptor completely. Therefore, the patient received androgen stimulation which resulted in good growth of his external genitalia and underwent surgical correction in the male direction. CONCLUSIONS: Diagnosis and therapy in affected patients will be improved identifying the molecular mechanisms that cause the various forms of sex ambiguity. Exact characterization of AR activation and function may offer a possible treatment modality in patients with the androgen insensitivity syndrome. Our results led to a surgical correction of our newborn patient in the male direction.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1998

Presence of chromogranins and regulation of their synthesis and processing in a neuroendocrine prostate tumor cell line.

BACKGROUND: Small-cell carcinoma and carcinoid tumors of the prostate display a neuroendocrine phenotype. To some extent, adenocarcinomas of the prostate also express neuroendocrine properties. Prostatic neuroendocrine tumors do not respond to androgen ablation therapy. The regulation of synthesis of chromogranins and their processing into neuropeptides have not yet been studied in neuroendocrine cells of the prostate. We used CRL-5813 cells which were derived from a metastasis from small-cell prostate cancer for studies on steroid receptor expression and chromogranin processing. METHODS: The expression of steroid receptor mRNA in CRL-5813 cells was examined by polymerase chain reaction. The synthesis and secretion of chromogranin- and secretogranin II-derived peptides were investigated by radioimmunoassays and high-performance liquid chromatography in untreated cells and in cells treated with the protein kinase A activator forskolin or basic fibroblast growth factor (bFGF). RESULTS: cDNA fragments for alpha-estrogen receptor and androgen receptor but not for beta-estrogen receptor, progesterone receptor, and glucocorticoid receptor were amplified from CRL-5813 cells. These cells were found to contain typical markers of large dense-core vesicles, i.e., chromogranins A and B and secretogranin II. Forskolin significantly stimulated the synthesis and secretion of the chromogranin B-derived peptide PE-11 and the secretogranin II-derived secretoneurin. bFGF significantly induced PE-11 protein levels in cell extracts. CONCLUSIONS. Our results demonstrate the expression of typical large dense-core vesicle proteins, i.e., chromogranins, in a small-cell prostate cancer cell line and their upregulation by a protein kinase A activator and, in part, by bFGF.

Cell Line↗
PubMed1997

Prostaglandin E2 and tumor necrosis factor alpha cooperate to activate human dendritic cells: synergistic activation of interleukin 12 production.

Interleukin (IL)-12 is a proinflammatory cytokine that contributes to innate resistance and to the development of antigen-specific T cell responses. Among other effects, prostaglandin E2 (PGE2) inhibits the production of IL-12 by macrophages activated with lipopolysaccharide (LPS). Here we investigated the effects of PGE2 on human dendritic cells (DCs) which develop in the presence of GM-CSF and IL-4. We demonstrate that in the absence of LPS, PGE2 dose dependently stimulated the production of IL-12 by DCs. Although PGE2 alone stimulated the production of low amounts of IL-12 only, it synergized with tumor necrosis factor (TNF)-alpha to induce high levels of IL-12 production by DCs. Addition of TNF-alpha in the absence of PGE2 had no effect on IL-12 production. Conversely, in the presence of LPS, PGE2 inhibited IL-12 production by DCs in a dose-dependent manner. The combination of PGE2 and TNF-alpha efficiently silenced mannose receptor-mediated endocytosis in DCs and readily induced neo-expression of the CD83 antigen. In addition, the expression of various surface antigens such as major histocompatibility complex class I and II, adhesion, as well as costimulatory molecules was upregulated by this treatment. The effects of PGE2 on IL-12 synthesis and CD83 expression could be mimicked by dibutyryl-cAMP and forskolin, indicating that they were due to the intracellular elevation of cAMP levels. DC treated with PGE2 and TNF-alpha were most potent in stimulating allogeneic T cell proliferation. Our data demonstrate that PGE2 contributes to the maturation of human DCs and that PGE2 can be a potent enhancer of IL-12 production by human DCs.

Antigen Presentation↗
PubMed1997

Prostate carcinoma screening in the county of Tyrol, Austria: experience and results.

BACKGROUND: This article summarizes the experience and results of different prostate carcinoma screening projects using total prostate specific antigen (PSA) as the initial test and different diagnostic tests to improve specificity. METHODS: The seven projects studied included 1) a mass screening study using PSA as the initial test in 21,079 volunteers; 2) an investigation of the usefulness of normal and age-referenced PSA cutoffs in 1618 men; 3) a PSA-based screening study of 2272 asymptomatic blood donors; 4) an investigation of the incidence and clinical significance of transitional zone carcinoma in 340 men with negative rectal examination findings and clearly visible prostatic zones on three-dimensional transrectal ultrasound; 5) determination of percent free PSA in one retrospective and two prospective screening studies to define the optimal range of total PSA and determine the appropriate cutpoints for percent free PSA within this range; 6) evaluation of the diagnostic benefit of PSA transitional zone density in 308 screening volunteers; and 7) a study of the impact of PSA-based screening on the percentage of incidental prostate carcinoma diagnosed in 1543 men undergoing transurethal resection of the prostate. RESULTS: 1) Of the 21,078 volunteers, 1618 (8%) had elevated PSA levels. Of these men, 778 (48%) underwent biopsies; 197 biopsies (25%) were positive for prostate carcinoma and 135 patients underwent radical prostatectomy. Ninety-five of the 135 pathologically staged lesions (70%) were found to be organ-confined. 2) A PSA cutoff of 2.5 ng/mL in men age 45-49 years and of 3.5 ng/mL in men age 50-59 years with normal digital rectal examination findings resulted in an 8% increase in both the number of biopsies (66 of 778) and the detection rate of organ-confined disease. 3) Of the 2272 men, 284 had elevated PSA levels and prostate carcinoma was detected in 62 men. All patients underwent radical prostatectomy and histologic examination revealed organ-confined disease in all but eight men. 4) Ninety-eight of 340 men (28.8%) had biopsies positive for carcinoma; 28 of these patients (28.5%) had carcinoma that originated in the transitional zone only. 5) In the retrospective study, receiver operating characteristic curve analysis showed that by using a percent free PSA of 18% as a biopsy criterion in men with an elevated PSA serum level, 37% of the negative biopsies could be eliminated although 94% of all carcinomas would still be detected. In the first prospective study, 106 of 158 men with elevated total PSA values between 2.5 and 10.0 ng/mL were further evaluated and 37 prostate carcinomas were detected. By using a percent free PSA of < or =22% as a biopsy criterion, 30% of the negative biopsies could be eliminated although 98% of the carcinomas would still be detected. In the second prospective study, 120 of 465 men with total PSA levels between 1.25 and 6.49 ng/mL, a percent free PSA of <18%, and normal digital rectal examination findings were further evaluated and 27 (22.5%) were found to have prostate carcinoma. 6) Receiver operating characteristic curve analysis for PSA transitional zone density showed that by using a PSA transitional zone density of >0.22 ng/mL/cc as a biopsy criterion, 24.4% of negative biopsies could be avoided without missing the detection of a single carcinoma. 7) In the prescreening era the incidence of T1a Grade 1 and 2 carcinomas was 3.1% and the incidence of T1a Grade 3 and T1b carcinoma was 2.3%, whereas in the years after the establishment of PSA-based screening the incidence was 4.6% and 1.03%, respectively. CONCLUSIONS: These data suggest that PSA-based screening increases the detection rate of clinically significant and organ-confined tumors. Percent free PSA and PSA transitional zone density provide an additional diagnostic benefit over total PSA.

Age Factors↗
PubMed1997

Synergistic activation of androgen receptor by androgen and luteinizing hormone-releasing hormone in prostatic carcinoma cells.

BACKGROUND: We investigated modulation of androgen receptor (AR) activity in prostatic tumor cells by luteinizing hormone-releasing hormone (LHRH)-induced increase of the intracellular cyclic adenosine monophosphate (cAMP) level. METHODS: AR transactivation activity was assessed in transiently transfected DU-145 and in LNCaP cells. RESULTS: LHRH and cAMP derivative, respectively, induced reporter gene activity to about 15% of the maximal level in DU-145 cells transfected with an AR expression vector and an androgen-inducible reporter gene. LHRH or the cAMP analogue acted synergistically in combination with low concentrations of androgen thus lowering the androgen concentration required for maximal AR activation by a factor of 100. A similar activation of the AR by cAMP analogue was observed in LNCaP cells when enhancement of androgen-induced secretion of prostate-specific antigen was determined. The two nonsteroidal antiandrogens hydroxyflutamide and Casodex(R) inhibited reporter gene activity. CONCLUSIONS: The AR is synergistically activated by low doses of androgen and LHRH or the second messenger cAMP. This may have implications for the treatment of advanced prostate cancer.

Androgen Antagonists↗
PubMed1997

Basic fibroblast growth factor levels in cancer cells and in sera of patients suffering from proliferative disorders of the prostate.

BACKGROUND: Both benign and malignant growth of the prostate depend on the induction of a microvasculature. Basic fibroblast growth factor (bFGF), a potent angiogenic factor, is thought to play an important role in this process. METHODS: bFGF expression in prostatic carcinoma was assessed by ELISA, reverse transcription polymerase chain reaction, and immunohistochemistry. RESULTS: DU-145 and PC-3 tumor cells produced bFGF. Almost 80-90% of it was localized in the cytoplasm, and 10-20% was associated with extracellular matrix components. Immunohistochemical analysis of prostatic tissue sections showed that cancer cells stained more intensively as compared to putatively healthy epithelium. In prostate cancer patients, mean bFGF serum levels were significantly elevated when compared to a healthy control group (6.64 pg/ml vs. 1.28 pg/ml). Serum bFGF levels did not correlate with any other clinical marker such as PSA, tumor stage, or grade. Four out of five patients who progressed to a more advanced stage showed an increase in serum bFGF levels. CONCLUSIONS: These results suggest that increased bFGF release may be associated with a more aggressive tumor phenotype.

Adult↗
PubMed1997

Improvement of prostate cancer screening by determination of the ratio free/total PSA in addition to PSA levels.

BACKGROUND: The measurement of prostate specific antigen (PSA) is widely used in screening programs for early detection of prostate cancer. However the specificity for cancer detection is limited because serum PSA is also elevated in patients with benign prostatic-hyperplasia (BPH) and/or prostatitis. It has been shown recently, that the ratio of free/total PSA in serum is lower in malignant prostatic disorders than in non-malignant ones and therefore might be a parameter to improve screening specificity. In a retrospective study, we tested whether free/total PSA helps to distinguish between BPH and prostatic carcinoma in men with elevated serum PSA. METHODS: A total of 266 men have been identified with age-specific elevated serum PSA levels using a conventional PSA determination kit. Subsequently their disease was proven by biopsies. Free and total PSA levels in these serum samples were measured using the DELFIA PSA dual label free/total PSA kit. RESULTS: The mean free/total PSA of 64 patients with prostate cancer was 0.10 and was significantly (P = 0.001) different from the mean free/total PSA of 202 men who were histologically free of cancer, which was 0.17. Receiver-operating-characteristic curve (ROC) analysis showed that using a free/total PSA ratio of 0.18 as a biopsy criterion in men with an elevated PSA serum level, 37% of the negative biopsies could be eliminated while still detecting 94% of all carcinomas. CONCLUSIONS: These results show that the ratio of free/total PSA is a useful determination and can improve specificity of prostate cancer screening.

Aged↗
PubMed1997

Human prostatic smooth muscle cells in culture: estradiol enhances expression of smooth muscle cell-specific markers.

Smooth muscle cells (SMCs) constitute a major cellular component of prostatic stroma. SMC tension plays an important role in urethral obstruction secondary to benign prostatic hyperplasia (BPH). We have developed an in vitro procedure for the propagation of human prostatic SMCs. Tissue specimens from patients undergoing radical prostatectomy or cystectomy were enzymatically disaggregated and cultured in MCDB-131 medium supplemented with horse serum, insulin, conditioned medium from the tumor cell line CRL-5813, and steroid hormones. The medium was assembled on the basis of the effects these supplements have on the growth of SMC cultures and on the expression of the two markers desmin and smooth muscle myosin. Addition of 0.1 microM of estradiol to the growth medium dramatically increased expression of these SMC-specific markers. Dihydrotestosterone (DHT) and hydrocortisone had a similar, albeit less pronounced effect. At three to five passages, about two thirds of the cells were immunohistologically positive for smooth muscle myosin or desmin. Almost all cells were positive for the myofibroblast marker smooth muscle alpha-actin throughout 10 passages and more. In SMC cultures, cells staining for smooth muscle myosin and desmin were found to seek direct contact to myofibroblasts. They grew in aggregates on a layer of myofibroblasts which adhered to the surface of the culture vessel. As revealed by transmission electron microscopy the cultured cells exhibited morphological features of myofibroblasts. Characteristics of smooth muscle cells, such as prominent bundles of microfilaments associated with dense bodies, basal laminae investing the cells, and numerous caveolae at the cell surfaces were regularly observed in cultures of low passages. After several passages, these features were markedly decreased and organelles of the biosynthetic system became more prominent. In summary, we present an in vitro model of prostatic SMCs and demonstrate that steroid hormones have characteristic effects on these cells. SMC cultures are expected to facilitate investigation of the functions and properties of human prostatic SMCs.

Actins↗
PubMed1997

Frequency and clinical significance of transition zone cancer in prostate cancer screening.

Approximately 20% of prostate cancers originate in the transition zone (TZ). Although transrectal ultrasound (TRUS) and systematic biopsies have improved peripheral zone (PZ) cancer diagnosis, additional biopsies directed into the TZ may further improve cancer detection. To evaluate the frequency and clinical significance of TZ cancers, we added two TZ biopsies to the routinely performed sextant biopsies. Three hundred forty patients (aged 45-75) from our prostate-specific antigen (PSA) screening study (21,078 volunteers) with negative rectal examination findings underwent systematic and TZ biopsies with three-dimensional ultrasound equipment. All patients had elevated PSA levels according to age-specific reference ranges. Ninety-eight of 340 men (28.5%) had biopsies positive for cancer. Of these 98 cancers, 28 (28%) originated in the TZ only and 5 (5%) were located in the TZ as well as the PZ. Eight men showed TZ abnormalities on ultrasound images, of whom four had biopsies positive for TZ cancer. The TZ cancers detected were pathologically significant in 96% (27 of 28). Seventy-one percent (20 of 28) of pathologically staged cancers were found to be organ confined and all combined TZ and PZ cancers were advanced tumors. We conclude that TZ biopsies enhance the cancer detection rate in prostate cancer screening and should therefore be added to the routinely done sextant biopsies in men with PSA elevation and normal digital rectal examination findings.

Aged↗
PubMed1997

Bacillus Calmette-Guérin mycobacteria stimulate human blood dendritic cells.

Bacillus Calmette-Guérin (BCG) mycobacteria have been used as adjuvant in the active immunotherapy of various human cancers. In addition, dendritic cells, which are the most potent antigen-presenting cells, have been shown to be capable of initiating anti-tumor immune responses. Here we investigated the effects of BCG on dendritic cells cultured from human blood. Addition of BCG resulted in rapid homotypic adhesion of dendritic cells. Moreover, BCG concentrations ranging from 10(4) to 10(6) bacteria/ml enhanced expression of the dendritic-cell-maturation antigen CD83 and of the T-cell co-stimulator CD86 (B7-2) in a dose-dependent manner. Concomitant with the increase of CD83 and CD86 expression, the cells lost the ability to capture soluble antigens, as determined by the exclusion of fluoresceinated Dextran molecules. Strikingly, the same dosages of BCG-bacteria stimulated TNF-alpha-gene transcription and TNF-alpha-protein release from dendritic cells in a dose-dependent fashion. BCG infection of dendritic cells in the presence of a neutralizing antibody directed against TNF-alpha inhibited CD83 expression by more than 50% indicating that the BCG-induced maturation of dendritic cells was at least partially mediated by dendritic-cell-derived TNF-alpha. The finding that BCG activates the most potent antigen-presenting cells reveals a plausible immunological mechanism of the occasionally observed anti-tumor activity of BCG.

Antibodies, Monoclonal↗
PubMed1997

PSA-based screening for prostate cancer in asymptomatic younger males: pilot study in blood donors.

BACKGROUND: The efficacy and success of a screening program for prostate cancer in young and healthy asymptomatic volunteers are described. METHODS: In the present study, prostate specific antigen (PSA) samples obtained from 2,272 males (aged 40-65 years) who donated blood at the local Red Cross Blood Bank were evaluated. Two groups of donors were distinguished, which were investigated in different ways. Group 1 comprised individuals aged 40-49 years (n = 568), while group 2 consisted of males aged 50-65 years (n = 1,704). Volunteers in group 2 who had PSA levels greater than 4 ng/ml (n = 302) were referred for ultrasound guided biopsy irrespective of findings on digital rectal examination (DRE). In group 2, individuals with PSA levels exceeding 4 ng/ml and positive DRE findings biopsy specimen was ordered (n = 2). In patients with unremarkable findings on DRE, serum PSA was determined 1 year later and in case of more than 20% increase in the PSA level biopsy was obtained under ultrasound guidance. RESULTS: The biopsy specimen yielded prostatic carcinoma in 58 patients in group 1. As a screening test, serum PSA determination was superior to digital rectal examination. On digital palpation only 2 presented with abnormal prostates. These 58 patients underwent radical prostatectomy and histological examination revealed organ-confined disease in all but 8. In group 2, in 4 of 12 males the biopsy specimen yielded prostatic carcinoma. CONCLUSIONS: This study shows that PSA measurement in blood donors is a useful method for recruiting screening volunteers, and therefore represents an additional possibility for early detection of prostate cancer in asymptomatic younger males. Furthermore, it represents an effective tool for following relatively young patients known to have a significant risk of prostate cancer.

Adult↗
PubMed1997

Metastatic lesions from prostate cancer do not express oestrogen and progesterone receptors.

Oestrogen receptors (ER) and progesterone receptors (PR) have been reported by several authors in the stromal cells of the human prostate. Controversial results exist on the expression of ER and PR in epithelial cells of the prostate. Some recent publications, in contrast to previous findings, have suggested that these receptors are also present in human prostate cancer cell lines derived from metastatic lesions. The expression of ER and PR in these cell lines has been re-examined to determine their presence in lymph node metastases from patients who did not receive any kind of endocrine therapy and in distant metastases obtained from patients who failed endocrine treatment. ER and PR expression in LNCaP, PC-3, and DU-145 cells was assessed by means of the reverse transcriptase-polymerase chain reaction, ligand binding assays, and immunohistochemistry. With all the techniques applied, the three cell lines were found to be negative for both ER and PR. Immunohistochemical analyses were performed in four lymph node metastases obtained at radical prostatectomy from patients who did not receive endocrine therapy and in 17 distant metastases obtained at palliative surgery from patients who failed endocrine therapy. All 21 metastases were negative for ER and PR on immunohistochemistry. These results do not support the recently developed concept that receptors for oestrogenic and progestagenic steroids are present in metastases from human prostate cancer.

Bone Neoplasms↗
PubMed1997

The role of oxygen metabolism for the pathological phenotype of Fanconi anemia.

The molecular defect of the hereditary disease Fanconi anemia (FA) remains unknown. The two theoretical possibilities are (1) an impaired DNA crosslink-repair system or (2) a disturbed oxygen metabolism either by overproduction of reactive oxygen intermediates (ROI) or by diminished detoxification of ROI. In order to gain further insight into the molecular mechanism of this disease, we have determined the repair capacity of FA cells challenged by crosslinking agents and have analyzed diverse biological systems that are involved in oxygen metabolism. We have tested normal and FA cells for oxygen consumption and for the activity of the antioxidant phospholipid-hydroperoxide-glutathione-peroxidase (PHGPx). FA cells show a reduced oxygen consumption and an increased PHGPx activity. Since spontaneous and induced chromosomal instability is a main cellular feature of FA, we have analyzed the redox state of cells and the effect of cytochrome P-450 (Cyt P-450) inhibitors and inducers on chromosomal breaks and micronuclei production. Our results indicate that Cyt P-450 enzymes, especially Cyt P-450 1A2, play a crucial role in radical metabolism in FA cells. Furthermore, we have determined NF-kappa B activity in untransformed cells and in SV40-transformed cells by gel shift experiments. NF-kappa B is a multiunit transcription factor that is known to be induced by ROI and that activates the expression of various genes involved in cellular responses to stress. NF-kappa B is constitutively induced in SV40-transformed FA cells probably as a consequence of an increased ROI level. Our results suggest that enzymatic defects in oxygen metabolism mediate the FA phenotype via impaired reactivity with ROI. Cyt P-450 1A2 appears to be a good candidate for the defective enzyme, even though no differences have been measured in the activity of this enzyme in FA and control fibroblasts in pilot experiments.

Cell Line↗
PubMed1997

Expression of transforming growth factors beta-1, beta 2 and beta 3 in human bladder carcinomas.

We previously detected elevated transforming growth factor beta-1 (TGF-beta1) serum levels in patients with invasive bladder carcinomas. In this study, we therefore investigated whether elevated serum levels correlate with enhanced TGF-beta expression in human bladder tumours. mRNA levels of TGF-beta1, -beta2 and -beta3 were reduced in bladder tumour tissue to 86%, 68% and 56%, respectively, of the levels in normal urothelium. On the other hand, TGF-beta1 protein levels were found to be higher in superficial tumours (Ta-T1) (mean level of 0.153 ng mg(-1)) and in invasive T2/T3 tumours (mean level of 0.104 ng mg(-1)) compared with normal urothelium (mean level of 0.065 ng mg(-1)). Invasive T4 tumours, however, contained only low amounts of TGF-beta1 (mean level of 0.02 ng mg(-1)). Neither in mean nor in individual patients were serum and tissue TGF-beta levels correlated with each other. Cell culture experiments on primary bladder cells revealed a 57% decrease in TGF-beta1 mRNA levels in tumour compared with normal epithelial cells. Tumour epithelial cells contained about two times higher levels of TGF-beta2 and TGF-beta3 mRNA than normal epithelial cells. Fibroblasts expressed about the same amount of TGF-beta1 or TGF-beta2 as epithelial cells. Yet, fibroblasts released only 19% and 13% of the amount secreted by tumour epithelial cells into the supernatant. TGF-beta3, on the other hand, was expressed by fibroblasts with higher levels than by epithelial cells. TGF-beta1 was the predominent isoform in bladder tissue and cells at protein as well as on mRNA levels indicating that TGFs-beta2 and -beta3 are of minor importance in bladder cancer. In summary, there is a lack of correlation between TGF-beta serum levels and TGF-beta expression in tumour tissue in bladder cancer.

Base Sequence↗
PubMed1997

Androgen receptor gene mutations in prostate cancer. Implications for disease progression and therapy.

Recent studies indicate that androgen receptors are present in all histological types of prostatic tumours, in relapsed prostatic carcinomas and in tumour metastases, even those obtained from patients in whom endocrine therapy was unsuccessful. Several research groups have asked whether structurally altered androgen receptors might be present in human prostatic tumours. The first androgen receptor mutation in prostate cancer was detected in the tumour cell line LNCaP. The frequency of androgen receptor mutations in primary tumours of the prostate is relatively low. In contrast, a high frequency of mutations has been reported in bone metastases from patients who did not respond to endocrine therapy. This fact may reflect genetic instability in these late tumour stages. Mutant androgen receptors detected in human prostate cancer cells are 'promiscuous receptors'; that is, they are activated not only by synthetic and testicular androgens, but also by adrenal androgens, products of dihydrotestosterone metabolism, estrogenic and progestagenic steroids, and even by nonsteroidal antiandrogens. Interestingly, the nonsteroidal antiandrogens hydroxyflutamide and nilutamide, but not bicalutamide, have been reported to have agonistic effects at mutant androgen receptors. It is speculated that the existence of androgen receptor mutations may explain, at least in part, the 'antiandrogen withdrawal syndrome': a temporary improvement in a subpopulation of prostate cancer patients following cessation of an antiandrogen from a therapeutic protocol. Further studies on androgen receptor alterations in prostate cancer should focus on metastatic specimens obtained from the late stages of this disease.

Humans↗
PubMed1997

In vitro generation of CD83+ human blood dendritic cells for active tumor immunotherapy.

There is increasing clinical interest in dendritic cells that are capable of initiating antitumor immune responses. Dendritic cells cultured from human blood mononuclear cells using granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) are competent for antigen uptake but express relatively low levels of costimulatory molecules and thus correspond to immature resident tissue dendritic cells. In this study we took advantage of the new dendritic cell-specific marker CD83, which is expressed by mature dendritic cells, to delineate the maturation of cultured human blood dendritic cells. Although dendritic cells cultured with GM-CSF and IL-4 contained transcripts for CD83 as determined by reverse transcription PCR, CD83 protein was barely detectable by flow cytometry, confirming that dendritic cells obtained with this system are immature. However, treatment of dendritic cells with tumor necrosis factor-alpha (TNF-alpha) significantly increased the levels of CD83 transcripts and induced CD83 protein expression in dendritic cells. In contrast to the initiation of dendritic cell culture, which was facilitated by high cell density (5 x 10(6) cells/mL), differentiation into CD83+ dendritic cells required a low cell concentration (0.5 x 10(6) cells/mL). At higher cell density (1 x 10(6) cells/mL), CD83 expression was suppressed and was almost completely prevented at 2 x 10(6) cells/mL. Induction of CD83 expression was accompanied by a strong upregulation of the costimulator B7-2 (CD86) on dendritic cells. While untreated CD83(-) dendritic cells efficiently internalized fluoresceinated Dextran, TNF-alpha treated CD83+ dendritic cells excluded these molecules, confirming that maturation of dendritic cells was associated with the silencing of the antigen-capturing machinery. Morphologically, CD83+ dendritic cells presented with pronounced cytoplasmic projections (veils) characteristic of mature dendritic cells. In summary, we show that cell density critically regulates dendritic cell development. Knowledge of the appropriate conditions for dendritic cell generation and maturation will be important in clinical immunotherapy settings.

Antigens, CD↗