The antiapoptotic effect of IL-6 autocrine loop in a cellular model of advanced prostate cancer is mediated by Mcl-1.

Levels of the proinflammatory cytokine interleukin-6 (IL-6) are increased in therapy-resistant prostate cancer. IL-6 has been considered a positive growth factor in late-stage prostate cancer cells and a potential target for therapeutic interference. Effects of inhibition of IL-6 on cell survival were studied in LNCaP-IL6+ cells, a model system for advanced prostate cancer, which produce IL-6. We show that the autocrine IL-6 loop is responsible for resistance to apoptosis and increased cellular levels of myeloid cell leukemia-1 (Mcl-1) protein, an antiapoptotic member of the Bcl-2 family. Treatment of cells with a chimeric anti-IL-6 antibody (CNTO 328) led to the induction of apoptosis and downregulation of Mcl-1 protein levels. Specific knockdown of Mcl-1 gene expression by small interfering RNA also yielded an increase in apoptosis of LNCaP-IL-6+ cells. Vice versa, inactivation of IL-6 autocrine loop had no influence on apoptosis levels in the absence of Mcl-1, thus suggesting this molecule as a mediator of the survival action of IL-6. Mcl-1 protein regulation by the endogenous cytokine directly involved the extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase pathway. Our data support the concept of anti-IL-6 targeted therapy in therapy-resistant prostate cancer.

Interleukin-6 and prostate cancer progression.

Prostate cancer, while initially dependent on androgens for proliferation, progresses to an androgen-independent state. Evidence has been accumulating that interleukin-6 (IL-6) may contribute to prostate cancer progression. Serum levels of IL-6 correlate with prostate tumor burden and patient morbidity. The prostate tissue itself appears to be a source of IL-6 and its receptor. Furthermore, experimental data suggest that IL-6 is an autocrine and paracrine growth factor for androgen-independent prostate cancer cell lines. For example, inhibition of IL-6, with anti-IL-6 antibody, sensitizes androgen-independent prostate cancer cells to chemotherapeutic agents in vitro. Finally, IL-6 activates a variety of signal transduction cascades, some which stimulate androgen receptor activity, in prostate cancer cells. These data suggest that targeting IL-6 may have multiple benefits in prostate cancer patients.

Distant metastases from prostatic carcinoma express androgen receptor protein.

Nearly all primary prostatic carcinomas have been found to express the androgen receptor (AR) protein, which is the intracellular mediator of androgen action. To gain a better insight into the mechanisms of androgen independence of advanced prostatic carcinoma, it is important to know whether the AR is also present in metastases of androgen-independent tumors. We have assessed the status of the AR and the prostate-specific antigen in 22 metastases of 18 patients with progressive prostate cancer. In 18 cases, the metastases were localized in bone, in 3 cases in the epidural space, and in 1 case in the periosteum. All but one patient had received some kind of endocrine treatment for prostatic carcinoma. Paraffin-embedded tissue sections were stained for the AR following a streptavidinbiotin-peroxidase protocol with the polyclonal antibody PG-21, which is directed against amino acids 1 through 21 of the rat and the human AR. The percentage of AR-positive cells was evaluated on the basis of an arbitrary 4-point scale. All 22 tumor metastases displayed AR positivity. One AR-positive metastatic lesion did not stain for prostate-specific antigen, but in all other metastases, this protein was detected by means of immunohistochemistry. The present study provides evidence that, unlike androgen-independent prostatic carcinoma cell lines, distant prostatic carcinoma metastases do express the AR. These findings indicate that the AR may be involved in the progression of prostate cancer.

Androgen receptor activation in prostatic tumor cell lines by insulin-like growth factor-I, keratinocyte growth factor, and epidermal growth factor.

Aberrant activation of the androgen receptor (AR) may be one of the mechanisms which contribute to progression of prostatic carcinoma to an androgen-independent stage. We investigated effects of growth factors on stimulation of the AR-mediated gene transcription in human prostatic tumor cell lines. DU-145 cells, which do not contain endogenous AR, were cotransfected with an androgen-inducible chloramphenicol acetyltransferase (CAT) reporter gene and an AR expression vector. The reporter gene (CAT) was driven either by artificial promoters consisting of one or two androgen-responsive elements in front of a TATA box or by the promoter of the prostate-specific antigen (PSA) gene, a naturally occurring androgen-inducible promoter. Insulin-like growth factor-I (IGF-I), at a concentration of 50 ng/ml, stimulated AR-mediated reporter gene transcription to the same extent as the synthetic androgen methyltrienolone. This growth factor was effective irrespective of the nature of the androgen-inducible promoter. Keratinocyte growth factor (KGF) and epidermal growth factor (EGF), at concentrations of 50 ng/ml, activated CAT reporter gene transcription only in experiments in which the artificial promoter with two androgen-responsive elements was used. Insulin-like growth factor-II and basic fibroblast growth factor displayed no effect on AR-mediated gene transcription. None of the growth factors stimulated reporter gene activity in control experiments when added to cells cotransfected with the CAT gene and an empty expression vector. AR activation by IGF-I, KGF, and EGF was completely inhibited by the pure AR antagonist casodex, showing that these effects are AR mediated. Activation of endogenous AR by growth factors was studied in the LNCaP cell line by determination of PSA secretion. IGF-I, at a concentration of 50 ng/ml, increased the PSA level in the supernatant of this cell line 5-fold. Again, the IGF-I effect on PSA secretion was blocked by casodex. Our results provide evidence that IGF-I, KGF, and EGF directly activate the AR in the absence of androgens, which means that the androgen-signaling chain may be activated by growth factors in an androgen-depleted environment. These findings may have implications for endocrine therapy for metastatic prostatic carcinoma.

Interleukin-6 regulates prostate-specific protein expression in prostate carcinoma cells by activation of the androgen receptor.

Interleukin-6 (IL-6) levels are frequently elevated in sera of patients with metastatic prostate cancer. IL-6 receptors are expressed in prostate cancer cell lines, as well as in benign prostate hyperplasia and prostate cancer tissue specimens. The androgen receptor (AR) is a key transcription factor that is present in all stages of prostate carcinoma, even in therapy-refractory tumors. In an attempt to investigate possible cross-talk between IL-6 and androgen signal transduction cascades, we tested the effects of this cytokine on AR transcriptional activity. The regulation of AR activity by IL-6 was studied in DU-145 cells, which were cotransfected with the androgen-responsive reporter plasmid ARE2TATACAT and the AR expression vector pSG5AR. We show that IL-6 up-regulates AR activity in a ligand-independent manner, as well as synergistically, with very low doses of the synthetic androgen methyltrienolone (5-10 pM). Therefore, AR activation by IL-6 may be operative in prostate cancer patients who have decreased androgen levels because of androgen ablation therapy. The maximal induction of reporter gene activity by IL-6 alone (50 ng/ml) was 67% of that stimulated by 1 nM of methyltrienolone. The nonsteroidal antiandrogen bicalutamide (Casodex) nearly completely inhibited AR activation by IL-6. IL-6 effects on AR activity were also abolished or greatly reduced by inhibitors of protein kinase A and C and mitogen-activated protein kinase pathways. In concordance with the results obtained in DU-145 cells, IL-6 induced AR-regulated prostate-specific antigen mRNA and protein in LNCaP cells. Stimulation of prostate-specific antigen protein secretion by IL-6 was antagonized by bicalutamide and inhibitors of protein kinase A and mitogen-activated protein kinase signaling pathways. Taken together, our data show for the first time that IL-6 is a nonsteroidal activator of the AR and that this activation is implicated in the regulation of prostate-specific proteins. Keeping in mind that IL-6, its receptor, and the AR are expressed in prostate cancers, cross-talk between IL-6 and AR signaling pathways may have clinical significance.

Mechanisms of endocrine therapy-responsive and -unresponsive prostate tumours.

Several options for the endocrine treatment of non-organ-confined prostate cancer are available. They include surgical or medical removal of androgenic hormones or administration of non-steroidal anti-androgens. However, tumour progression after a period of remission of the disease inevitably occurs in virtually all patients. The androgen receptor (AR) is, in various tumour models, implicated in the development of therapy resistance but molecular mechanisms that by-pass the receptor have also been described. Adaptation mechanisms relevant to tumour recurrence include up-regulation of AR mRNA and protein, overexpression of AR coactivators, increased activation of mutated receptors by steroids and anti-androgens, and ligand-independent activation. For research studies, sublines that respond to but do not depend on androgen for their proliferation were generated. Coactivators SRC-1, TIF-2, RAC3, p300, CBP, Tip60, and gelsolin are highly expressed in endocrine therapy-resistant prostate cancer. AR point mutations are increasingly detected in relapsed cancers and contribute to the failure of endocrine therapy in a subgroup of patients. Ligand-independent activation of the AR by HER-2/neu and interleukin-6 is associated with activation of the signalling pathway of mitogen-activated protein kinase. Increased activity of intracellular kinases may affect cellular events in both an AR-dependent and -independent manner. Mitogen-activated protein kinases are strongly phosphorylated in endocrine therapy-resistant prostate tumours. Similarly, activation of the AR by phosphorylated protein kinase B, Akt, has also been reported in prostate cancer. Activation of the Akt pathway contributes to increased survival of prostate tumour cells.

Prostate cancer cells (LNCaP) generated after long-term interleukin 6 (IL-6) treatment express IL-6 and acquire an IL-6 partially resistant phenotype.

PURPOSE: The levels of interleukin-6 (IL-6) are frequently elevated in sera from patients with advanced prostate carcinoma. Our main objective was to investigate changes in responsiveness to IL-6 and/or androgen that occur in LNCaP cells after long-term treatment with IL-6. This in vitro model could be of clinical relevance because of its similarity with late-stage prostate carcinoma. EXPERIMENTAL DESIGN: LNCaP human prostate cancer cells were treated with IL-6 at a concentration of 5 ng/ml. After 20 passages, the new subline LNCaP-IL-6+ has been established. Passages 20-40 are referred to as low passages (LP) and passages 41-73 as high passages (HP). LNCaP cells passaged at the same time in the absence of IL-6 were used as controls (LNCaP-IL-6-). Cells were counted after treatment with either IL-6 or the synthetic androgen methyltrienolone (R1881), and cell cycle analysis was performed. Binding of IL-6 or R1881 was assessed by radioligand binding assays. Reporter gene activity was measured by chloramphenicol acetyltransferase assay. Prostate-specific antigen in LNCaP-IL-6+ supernatants was measured by an enzyme immunoassay. Expression of IL-6 mRNA and protein was assessed by reverse transcription-PCR and ELISA, respectively. RESULTS: The basal proliferation rate in HP LNCaP-IL-6+ cells was higher than that in LNCaP-IL-6- cells. IL-6 inhibited proliferation of LNCaP-IL-6- cells but not that of either LP or HP of LNCaP-IL-6+ cells. This inability to elicit a growth-inhibitory response was associated with lack of effect on cell cycle distribution in the LNCaP-IL-6+ subline. In parallel, IL-6 binding decreased gradually during long-term IL-6 treatment and, in HP, reached only 33% of the levels measured in controls. Binding of radiolabeled androgen increased 2-fold in HP LNCaP-IL-6+ cells. Reporter gene assays revealed that R1881, at nanomolar concentrations, was a more potent androgen receptor activator in LNCaP-IL-6+ than in LNCaP-IL-6- cells. However, androgen- and IL-6-induced prostate-specific antigen secretion decreased in long-term IL-6-treated cells. IL-6 cDNA fragments were detected by reverse transcription-PCR in HP LNCaP-IL-6+ cells but not in controls or LP. IL-6 protein was first detected in passage 36 of LNCaP-IL-6+ cells, and it increased in HP. CONCLUSIONS: Long-term treatment of LNCaP human prostate cancer cells with IL-6 leads to abolishment of inhibitory growth response. In contrast to control cells, the LNCaP-IL-6+ subline expresses IL-6 mRNA and protein.

Mutant androgen receptor detected in an advanced-stage prostatic carcinoma is activated by adrenal androgens and progesterone.

Structural changes of the androgen receptor (AR) may contribute to the development of resistance to endocrine therapy in prostatic carcinoma. We have isolated AR cDNA fragments from seven tumor specimens derived from patients with advanced metastatic prostatic tumors. In one specimen obtained from a patient who failed to respond to endocrine and cytotoxic therapy we have detected a point mutation in the hormone-binding domain of the receptor. This AR mutation is a guanine-to-adenine transition at nucleotide 2671 that leads to substitution of methionine for the wild type valine at position 715. It is a somatic mutation because it was not present in the AR genomic DNA fragments isolated from prostatic and testicular tissues of the same patient. The mutant AR was recreated in an expression vector and transiently expressed in COS-7 and CV-1 cells. Hormone-binding assays revealed that the mutant receptor does not differ from the wild type receptor in its ability to bind androgen. The dissociation constant for the synthetic androgen mibolerone was 3 nM for both receptors. There was also no significant difference in binding of other steroids and nonsteroidal antiandrogens as revealed by competition binding assays. However, transfection experiments to determine the trans-activation potential of the mutant receptor produced differences in the action of this receptor compared to the wild type receptor. Dihydrotestosterone and the synthetic androgens methyltrienolone (R1881) and mibolerone were equally proficient in conferring trans-activation activity to both the mutant and wild type receptors. Adrenal androgens such as dehydroepiandrosterone and androstenedione, as well as progesterone mediated a higher trans-activation through the mutant than through the wild type receptor. These data demonstrate that the exchange of a single valine into methionine at position 715 in the AR promoters trans-activation not only by testicular but also by adrenal androgens and progesterone. This pattern of ligand-dependent trans-activation may have significance in the process controlling the progression of prostatic carcinoma.

Antiandrogens in prostate cancer endocrine therapy.

Prostate cancer is the most frequently diagnosed tumor in industrialized countries. Endocrine therapy, which is based on interference with androgen signaling is only palliative. Drugs used in prostate cancer therapy are luteinizing hormone releasing hormone (LHRH) agonists and antiandrogens. Application of LHRH agonists leads to suppression of the levels of circulating androgens, and antiandrogens block the function of the androgen receptor (AR). The steroidal antiandrogen cyproterone acetate and nonsteroidal compounds hydroxyflutamide and bicalutamide are used most frequently. They prevent acquisition of a transcriptionally active conformation of the AR. It became clear that tumors progress to therapy resistance in the presence of the AR which might be structurally altered. These mutations generate receptors that respond to other steroids and antiandrogens by increased activation. In addition, AR expression increases during endocrine treatment. AR is also activated by nonsteroidal compounds such as growth factors, interleukin-6, and neuropeptides. Therefore, new experimental approaches are needed to antagonize AR expression and function more efficiently. The AR associates with a number of proteins, coactivators and corepressors. There are indications that expression of some of these proteins is altered in prostate cancer, a fact which might be important for improvement of endocrine therapy.

Androgen receptors in prostate cancer.

The androgen receptor (AR), a transcription factor that mediates the action of androgens in target tissues, is expressed in nearly all prostate cancers. Carcinoma of the prostate is the most frequently diagnosed neoplasm in men in industrialized countries. Palliative treatment for non-organ-confined prostate cancer aims to down-regulate the concentration of circulating androgen or to block the transcription activation function of the AR. AR function during endocrine therapy was studied in tumor cells LNCaP subjected to long-term steroid depletion; newly generated sublines could be stimulated by lower concentrations of androgen than parental cells and showed up-regulation of AR expression and activity as well as resistance to apoptosis. Androgenic hormones regulate the expression of key cell cycle regulators, cyclin-dependent kinase 2 and 4, and that of the cell cycle inhibitor p27. Inhibition of AR expression could be achieved by potential chemopreventive agents flufenamic acid, resveratrol, quercetin, polyunsaturated fatty acids and interleukin-1beta, and by the application of AR antisense oligonucleotides. In the clinical situation, AR gene amplification and point mutations were reported in patients with metastatic disease. These mutations generate receptors which could be activated by other steroid hormones and non-steroidal antiandrogens. In the absence of androgen, the AR could be activated by various growth-promoting (growth factors, epidermal growth factor receptor-related oncogene HER-2/neu) and pleiotropic (protein kinase A activators, interleukin-6) compounds as well as by inducers of differentiation (phenylbutyrate). AR function is modulated by a number of coactivators and corepressors. The three coactivators, TIF-2, SRC-1 and RAC3, are up-regulated in relapsed prostate cancer. New experimental therapies for prostate cancer are aimed to down-regulate AR expression and to overcome difficulties which occur because of the acquisition of agonistic properties of commonly used antiandrogens.

An autocrine loop for vascular endothelial growth factor is established in prostate cancer cells generated after prolonged treatment with interleukin 6.

Concentrations of interleukin 6 (IL-6) and its receptor are increased in human prostate cancer. Prostate cancer LNCaP-IL-6+ cells, established after prolonged treatment with IL-6, have been found to acquire a growth advantage. Vascular endothelial growth factor (VEGF) may accelerate the growth of various tumours by stimulation of VEGF receptor 2 (VEGFR-2). To understand better the regulation of proliferation of LNCaP-IL-6+ cells, the expression of VEGF and VEGFR-2 was here investigated in the LNCaP-IL-6+ subline. VEGF was measured in cellular supernatants by enzyme-linked immunoassay. The expression of VEGFR-2 was assessed by Western blot. LNCaP-IL-6+ and control LNCaP-IL-6- cells were treated with a neutralising antibody against VEGFR-2. VEGF concentrations were 20-fold higher in LNCaP-IL-6+ than in LNCaP-IL-6- cells. The stimulatory effect of IL-6 on VEGF production was abolished by an inhibitor of the signalling pathway for phosphoinositol 3 kinase in LNCaP-IL-6+ and LNCaP-IL-6- cells. Exogenous VEGF did not stimulate proliferation in either LNCaP-IL-6+ cells or controls. VEGFR-2 was detected only in LNCaP-IL-6+ cells, in which the neutralising antibody caused a partial inhibition of cell proliferation. It was concluded that a VEGF autocrine loop is established in prostate cancer cells generated after chronic treatment with IL-6. Because of the upregulation of IL-6 in patients with prostate cancer, these findings might be clinically relevant.

Androgen receptor mutations in carcinoma of the prostate: significance for endocrine therapy.

Endocrine therapy for advanced prostate cancer involves androgen ablation (orchiectomy or application of luteinizing hormone releasing hormone analogs) and/or blockade of the androgen receptor (AR) with either steroidal (cyproterone acetate) or nonsteroidal (hydroxyflutamide, bicalutamide and nilutamide) antiandrogens. These antagonists prevent androgen-induced conformational change and activation of the AR. During long term androgen ablation, the AR adapts to an environment with low androgen concentrations and becomes hypersensitive to low concentrations of androgens, either alone or in combination with various cellular regulators. Bicalutamide can switch from antagonist to agonist during long-term androgen withdrawal, as shown in prostate cancer LNCaP cells. AR point mutations were detected in metastatic lesions from human prostate cancer more frequently than in primary tumors. Although functional characterization of only some mutant AR detected in prostate cancer tissue has been performed, data available suggest that they are activated by dihydrotestosterone, its precursors and metabolites, synthetic androgens, estrogenic and progestagenic steroids and hydroxyflutamide. A direct association between AR mutations and endocrine withdrawal syndrome has been investigated in only one study thus far. There is no evidence at present that activation of any of the mutant AR genes detected in prostate cancer is enhanced in the presence of a nonsteroidal AR stimulator. Coactivators of the AR are proteins that associate with the receptor, possess histone acetylase activity and facilitate AR activation. The coregulatory proteins ARA70 and ARA160 differentially affected the activity of the mutated AR Glu(231)-->Gly, which was discovered in a mouse authochthonous prostate tumor. ARA70 enhanced receptor activation by both androgen and estradiol, whereas ARA160 augmented only androgen-induced AR activity. Novel experimental therapies that down-regulate AR expression have been developed; they include the application of ribozymes and antisense oligonucleotides.

Characterisation of a collecting duct carcinoma by cytogenetic analysis and comparative genomic hybridisation.

Collecting duct carcinoma (CDC) is a rare variant of carcinoma of the kidney with aggressive behaviour. CDC arise from the epithelium of the ducts of Bellini in the distal nephron. A CDC in a 53-year old male patient is characterised both by cytogenetic analysis and comparative genomic hybridisation (CGH). The cytogenetic analysis shows a biclonal karyotype 47,XY,+3[2]/40-44,XY,-12[3], -22[4][cp5]/46,XY[42]. Loss of DNA sequences detected by CGH involves chromosome 1, 2, 9, 11 and 18. Gain of DNA sequences affect chromosome 16 and 20. The characterisation of a CDC in this study represents an additional contribution to the poorly explored CDC.

Combined study of prostatic carcinoma by classical cytogenetic analysis and comparative genomic hybridization.

Conventional cytogenetic analysis of prostatic carcinoma (PC) is characterized by inefficient growth of tumor cells during in vitro culture, leading to a lack of aberrant karyotypes in many of investigated tumors. In this study we have combined a modified short-term tissue culture method for conventional banding analysis and comparative genomic hybridization (CGH) to examine genetic changes in PC, and to evaluate the effect of the in vitro culture on chromosomal changes by comparing results of the two methods. Cytogenetic analysis was performed on 34 PCs using both, conventional and molecular methods. Tumor tissues were obtained predominantly from untreated primary tumors from 48 patients. For karyotyping all tumor samples were short-term cultured using a feeder layer technique. Additionally DNA from uncultured tumor material from 17 of those patients was isolated and screened for copy number changes using CGH. Conventional banding analysis: clonal aberrations were detected in 65% of the tumor samples. Most of the chromosomal findings were numerical changes, including loss of chromosomes Y (32%), 18, 19 and 21 (each 12%). Less frequent, trisomy of chromosome 7 and monosomy of chromosomes 9, 12 and 22 (each 9%) was found. Additionally an inversion of chromosome 9p and a deletion at chromosome 7q was found in two cases. In 35% no clonal aberrations could be detected. CGH: DNA copy number changes were detected in 65% of the analyzed tumors. Predominantly losses of DNA sequences were found. The most common losses were found at chromosome regions 13q21q33 (29%), 6q11q23 (24%), 16q, and 18 (each 18%), and the most common gains at 19 (18%). In six tumors no copy number changes were found. Both methods showed a similar aneuploidy rate, suggesting that the feeder layer technique is quite a suitable method for in vitro culture of PC cells. However, the two techniques produced substantially differing results for most of the tumor samples, and in some cases the discrepancies are quite striking. Therefore eventual culture effects need to be taken into account when comparing results from conventional cytogenetics and CGH. Some contrary findings from the two methods are discussed.

CD30 expression in seminoma.

In testicular germ cell tumors the CD30 antigen has been shown to be regularly expressed in embryonal carcinoma and was thus suggested as a marker for this particular neoplasm. Very recently, it has been proven that the monoclonal antibody Ber-H2 is suitable for the detection of this membrane antigen in paraffin sections. We conducted an immunohistochemical study to investigate the CD30 expression in a large series of different presentations of seminoma (ie, pure, mixed, and spermatocytic) because there is evidence from several sources that embryonal carcinoma is histogenetically closely related to, and probably derives from, seminoma. Sections from formalin-fixed, paraffin-embedded tissue from 38 cases of testicular seminomas were immunostained for the demonstration of the CD30 antigen using the monoclonal antibody Ber-H2, cytokeratins, and placental alkaline phosphatase following an indirect streptavidin-peroxidase regimen. In selected cases, immunostainings were performed on consecutive sections to investigate a possible colocalization of CD30 and cytokeratins in seminoma. Specific immunostaining for CD30 in seminoma cells could be detected in single minute foci in 4 of 21 cases of pure classic seminoma. Seminomatous components of mixed tumors showed CD30 positivity in single, but also multiple, foci in 7 of 14 cases. CD30 immunoreactivity in seminoma cells occurred with and without colocalized expression of cytokeratin. Spermatocytic seminoma (n = 3) as well as intratubular germ cell neoplasia in tumor adjacent parenchyma (n = 36) were negative in all cases investigated. We conclude that in testicular germ cell tumors, the expression of CD30 is not restricted to embryonal carcinoma but can also be found focally in seminoma, adding further evidence for a close relationship between these two tumors. The prevalence of CD30 expression in seminomatous components of mixed tumors, as well as the coexpression with cytokeratins, suggest that CD30 expression in seminomas might indicate their upcoming transformation to embryonal carcinoma. This conclusion coincides with a model featuring seminoma in a central role of germ cell tumor development.

Hyperactive androgen receptor in prostate cancer: what does it mean for new therapy concepts?

Investigations on androgen signaling alterations in the late stages of prostate cancer revealed new molecular mechanisms that may be in part responsible for failure of endocrine therapy. Both primary and metastatic lesions from prostate cancer express androgen receptor protein. Amplification of androgen receptor gene occurs in a subset of prostate cancer patients. Several point mutations of androgen receptor gene have been described; they generate receptors which are functionally activated by androgens, other steroids, and even by antihormones. The frequency of androgen receptor mutations may be high in tumor metastases. Functional activity of androgen receptor is influenced by nonsteroidal factors, such as peptide growth factors and second messengers. Thus, prostate cancer cells adapt to low androgen environment by various mechanisms utilizing androgen receptor. Therefore, new strategies for switching off the androgen receptor are needed.

Expression and function of androgen receptor in carcinoma of the prostate.

This article reviews recent findings on androgen receptor expression, structure, and function in carcinoma of the prostate. In this decade, it became clear that androgen-resistant prostate cancers contain androgen receptors and, therefore, regulation of androgen receptor expression and function receives considerable attention. The article summarizes findings on regulation of androgen receptor expression by androgens, growth factors, and protein kinase A activators. In addition, modulation of function of the wild-type and mutant AR is discussed. Androgen receptor functional activity is up-regulated by androgens and nonsteroidal activators, which influence transcription of androgen receptor-regulated genes in a cell type-dependent manner. This study also contains a chapter on androgen receptor-associated proteins, coactivators, and coreppressors and their possible role in pathological situations.

Clinical value of fructose 1,6 bisphosphatase in monitoring renal proximal tubular injury.

The usefulness of the gluconeogenic key enzyme fructose 1,6 bisphosphatase (FBPase), which is localized exclusively in the proximal nephron segment, as a marker compound to monitor injury of the proximal nephron segment during nephrotoxic therapy, was tested in a collective model of male patients treated for testicular cancer. These patients with normal kidney function were submitted to therapy with the nephrotoxic chemotherapeutics carboplatinum and a combination of cisplatinum, etoposide, bleomycin and ifosfamide. The release of FBPase activities into the urine was monitored during the initial two treatments over a period of eight days. The urinary enzyme activities measured were compared to the excretion of the "proximal tubular injury markers" N-acetyl-beta-D-glucosaminidase (NAG) and alpha 1-microglobulin (alpha 1m). The presence of glomerular damage was determined by measurement of urinary excretion rates of albumin (ALB) and IgG. In addition, protein excretion patterns following chemotherapy were monitored. The combined administration of cisplatin, etoposide and ifosfamide resulted in a pronounced proximal tubular injury as shown by the release of FBPase into the urine. This is substantiated by simultaneously increased excretion rates for NAG and alpha 1m. Proximal tubular toxicity was found to be less severe when cisplatin was combined with etoposide and bleomycin and was nearly absent following carboplatinum monotherapy. Carboplatinum only affected glomerular function and resulted in an elevated ALB and IgG excretion. From this model investigation it can be delineated that determination of urinary FBPase activities ensures a sensitive and reliable identification of proximal nephron damage.

Cytogenetic characterization of 22 human renal cell tumors in relation to a histopathological classification.

In this study, cytogenetic and fluorescence in situ hybridization analyses were performed on 22 sporadic, unilateral primary renal cell tumors. The tumors were classified according to cell types, growth patterns, and grades of malignancy. A feeder layer technique was used for the cell culture of 13 clear-cell carcinomas, 4 chromophilic carcinomas, 3 chromophobe carcinomas, 1 oncocytoma, and 1 spindle-shaped pleomorphic carcinoma. Eighty-six percent (19/22) of renal tumors showed clonal abnormalities. The most frequent finding in the 15 male patients was loss of chromosome Y (9/15). In 3/15, it was the only observed aberration. The second most visible aberration was regional loss or entire loss of chromosome 9, which was detected in 36% (8/22) of the cases. Four cases showed loss of chromosome 9 and 4 cases a deletion of the short arm with breakpoints on 9p11 and 9p21. Loss of 3p material was observed in 32% (7/22) of the cases but only in 2/13 patients with clear-cell carcinoma. Gain of chromosome 12 or 12p was observed in 27% (6/22). In 23% (5/22) of the patients, gain of whole or partial chromosomes 2, 5, and 7 was found. Less-frequent findings were loss of chromosomes 8, 14, and 21; gain of chromosome 16; and structural abnormalities of chromosome 1 (each 18%; 4/22). Only some of the karyotypes described as typical for the various renal tumor types were confirmed. In contrast with previous reports, chromosome 3 and 9 aberrations did not allow differentiation between tumor types in our study.

Laparoscopic retroperitoneal lymph node dissection for clinical stage I nonseminomatous testicular tumor.

OBJECTIVES: An appropriate laparoscopic technique for diagnostic retroperitoneal lymph node dissection in clinical Stage I testicular tumors is presented and its efficiency and morbidity are evaluated. METHODS: A two-step procedure has been developed. In the first step, a ventral approach is used. The colon is dissected free, then the spermatic vein is excised and the borders of dissection are defined. Via the ventral approach removal of retroaortic and retrocaval nodal tissue is technically not feasible. Therefore, in the second step, a lateral approach is used, which is the key to success because it permits straightforward transection of the lumbar vessels. Thus, complete lymph node dissection within the boundaries described by Weissbach can be achieved. Between August 1992 and March 1994, this procedure was performed in 15 patients. In 9 patients, the tumor was on the right side and in 6 it was on the left. RESULTS: Conversion to open surgery was necessary in 2 patients because of uncontrollable bleeding and a large metastasis. Microscopic metastasis were detected in 2 other patients. Apart from the bleeding just mentioned, no major complications occurred; no blood transfusions were required. CONCLUSIONS: The results obtained so far demonstrate that the technique is feasible and decreases postoperative morbidity. It therefore warrants further consideration.