Molekularbiologische Erklärungsansätze einer Lymphknotenmetastasierung

The spread of tumor cells of solid tumors to the regional lymph nodes is an important step in the progression of the disease and also an important prognostic factor. While the significance of the prognostic value of the lymphatic progression had been detected long ago, only increased knowledge of the molecular anatomy and mechanisms involved in the lymphatic spread of tumor cells provided a beginning insight into the understanding of lymphatic metastasis. One group of important molecular factors consists of proteins produced by the tumor cells inducing a proliferation of lymphatic vessels into the primary tumor. The vascular endothelial growth factors have been identified as key factors in this process. In addition there are hints for the fact that chemokines, which are cytokine-like proteins taking part in the regulation of processes of inflammation, and their chemokine receptors control cellular key steps of lymphatic metastasis of tumor cells such as migration, proliferation, and invasion. In conclusion new data point to the possible inhibition of lymphatic spread by selective blockade of growth factor receptors or chemokine receptors. The growing insight into cellular understanding of the mechanisms involved in the metastasis of tumor cells into the lymphatics and lymph nodes will hopefully facilitate the development of new diagnostic and therapeutic tools in the treatment of cancer patients.

[Proteasome inhibitors: induction of apoptosis as new therapeutic option in prostate cancer]

New perspectives in prostate cancer genesis and putative clinical management have emerged in recent years . Apoptosis plays a major role in this environment. Proteasome inhibitors block the action of a multicatalytic proteinase complex involved in the degradation of intracellular proteins, particularly with regard to cell cycle regulation and apoptosis. Numerous in vitro studies have demonstrated the ability of these compounds to induce apoptosis and enhance the activity of conventional tumoricidal agents in many cancer cell types, including prostate cancer cells. They point out the use of these potent inhibitors as a new potential molecular approach to the therapeutic management of prostate cancer. Furthermore, the action of proteasome inhibitors has been tested in animal models and in patients with hormone refractory prostate cancer, resulting in both PSA and tumor volume decrease. PS-341 (bortezomib, Velcade) is the first proteasome inhibitor with clinical application in cancer therapy that has been used in clinical trials to date. This report reviews the current status of those papers that have tried to analyze the connection between the proteasome pathway and apoptosis. We present our results of proteasome inhibition in individual prostate cancer cell lines. Proteasomal inhibition may offer a new therapeutic access in "molecular targeting" of prostate cancer.

Proteasome inhibitors and their combination with antiandrogens: effects on apoptosis, cellular proliferation and viability of prostatic adenocarcinoma cell cultures

The 26S proteasome is a ubiquitin-dependent proteolytic system that has been implicated in the regulation of cell cycle progression and apoptosis. We investigated the effects of the proteasome inhibitors MG115 and PSI alone or in combination with different concentrations of the antiandrogen hydroxyflutamide on the cellular proliferation, apoptosis and viability of 10 prostatic adenocarcinoma cell cultures. Treatment with both proteasome inhibitors resulted in apoptosis induction, whereas the combinations with hydroxyflutamide generally did not, with the exception of MG115 combined with 10(-7) M hydroxyflutamide. MG115 caused a significant decrease in cellular proliferation, as did the combinations of both proteasome inhibitors with hydroxyflutamide, whereas hydroxyflutamide alone was only effective at a concentration of 10(-5) M. Cellular viability was significantly reduced when both proteasome inhibitors were combined with 10(-5) M hydroxyflutamide. Although the results varied among different cell lines, we conclude that proteasome inhibitors are able to induce apoptosis and reduce cellular proliferation. They might prove effective as antineoplastic substances in prostatic adenocarcinoma alone or in combination with antiandrogens.

[Molecular diagnostics of prostate cancer]

Although a number of studies have identified molecular markers for prostate cancer, their clinical utility remains mainly unclear. Markers, which allow improved determination of the biological aggressiveness of individual prostate cancers, may help to optimize therapeutic management of this heterogeneous tumor type. Here, a subset of molecular markers, which are intensively discussed in the literature or which are supposed to gain clinical utility in the future, are described in more detail. For a better survey, the markers are divided into (a) susceptibility markers, (b) malignancy markers, and (c) aggressiveness markers. The number of markers described as well as the inconsistency across studies in assessing their clinical utility reflect the heterogeneity of prostate cancer also on a genetic level so that it is unlikely that a single marker will gain clinical relevance. Future research must include systematic analysis of the clinical utility of not only single markers but rather of marker profiles in appropriate studies.

Mucin 7 and cytokeratin 20 as new diagnostic urinary markers for bladder tumor

PURPOSE

We determine the sensitivity and specificity of cytokeratin 20 (CK-20) and mucin 7 (MUC7) gene expression in voided urine samples taken from patients with bladder tumor and from control groups to investigate putative, noninvasive urinary markers for bladder tumor detection and monitoring.

MATERIALS AND METHODS

Voided urine samples were collected from 50 patients with histologically proven bladder neoplasms (pTaN0M0G1-3 in 19 and pTisN0M0G3-pT4pN1M1G3 in 31), 20 patients with urolithiasis, 20 patients with urinary tract infection, 20 patients with other urological neoplasms and 20 healthy volunteers. Total RNA was extracted from exfoliated cells collected from 200 ml. voided urine. All RNA samples were investigated by a specific CK-20 and MUC7 nested reverse transcriptase polymerase chain reaction.

RESULTS

The overall sensitivity of CK-20 gene expression in voided urine samples for the detection of bladder neoplasms was 78%. In contrast, voided urine samples from control patients and healthy volunteers showed a high rate of false-positive CK-20 detection resulting in a low specificity of 36%. The overall sensitivity of the MUC7 test for all bladder tumor cases was 66%. The sensitivity for papillary urothelial neoplasms (pTaN0M0G1-3) was 42% whereas analysis of the carcinoma in situ and invasive bladder cancer group (pTisN0M0G3-pT4pN1M1G3) yielded a sensitivity of 81%. The overall specificity of the MUC7 nested reverse transcriptase polymerase chain reaction method in the control groups was 80%.

CONCLUSIONS

A high positive CK-20 detection rate was found not only in voided urine samples from patients with bladder tumor, but also in urine specimens from control groups. Therefore, CK-20 is not a reliable urinary tumor marker for bladder neoplasms. In contrast to CK-20, analysis of MUC7 demonstrated a high sensitivity and high specificity for carcinoma in situ and invasive bladder cancer, thus fulfilling the criteria of a urinary tumor marker.

Mucin 7 and cytokeratin 20 as new diagnostic urinary markers for bladder tumor

PURPOSE

We determine the sensitivity and specificity of cytokeratin 20 (CK-20) and mucin 7 (MUC7) gene expression in voided urine samples taken from patients with bladder tumor and from control groups to investigate putative, noninvasive urinary markers for bladder tumor detection and monitoring.

MATERIALS AND METHODS

Voided urine samples were collected from 50 patients with histologically proven bladder neoplasms (pTaN0M0G1-3 in 19 and pTisN0M0G3-pT4pN1M1G3 in 31), 20 patients with urolithiasis, 20 patients with urinary tract infection, 20 patients with other urological neoplasms and 20 healthy volunteers. Total RNA was extracted from exfoliated cells collected from 200 ml. voided urine. All RNA samples were investigated by a specific CK-20 and MUC7 nested reverse transcriptase polymerase chain reaction.

RESULTS

The overall sensitivity of CK-20 gene expression in voided urine samples for the detection of bladder neoplasms was 78%. In contrast, voided urine samples from control patients and healthy volunteers showed a high rate of false-positive CK-20 detection resulting in a low specificity of 36%. The overall sensitivity of the MUC7 test for all bladder tumor cases was 66%. The sensitivity for papillary urothelial neoplasms (pTaN0M0G1-3) was 42% whereas analysis of the carcinoma in situ and invasive bladder cancer group (pTisN0M0G3-pT4pN1M1G3) yielded a sensitivity of 81%. The overall specificity of the MUC7 nested reverse transcriptase polymerase chain reaction method in the control groups was 80%.

CONCLUSIONS

A high positive CK-20 detection rate was found not only in voided urine samples from patients with bladder tumor, but also in urine specimens from control groups. Therefore, CK-20 is not a reliable urinary tumor marker for bladder neoplasms. In contrast to CK-20, analysis of MUC7 demonstrated a high sensitivity and high specificity for carcinoma in situ and invasive bladder cancer, thus fulfilling the criteria of a urinary tumor marker.

[After-care of bladder carcinoma]

The present article offers an introduction to the aftercare of patients with carcinoma of the urinary bladder. These recommendations are based on the guidelines of the German Association of Urology and the European Association of Urology. Aftercare always depends on the risk of recurrence and progression of the primary tumor and the extent of the therapy applied. Thus, after transurethral resection of a superficial carcinoma of the urinary bladder, aftercare focuses on follow-up cystoscopy. Radical cystectomy of the muscle-invading and locally advanced carcinoma should be followed by extensive examinations, including computed tomography of the pelvis and the abdomen. In addition, the various forms of urinary diversion after cystectomy with its specific late complications should be included in the aftercare. Moreover, the psychological significance of the follow-up examinations should not be neglected.

Comparison of the malignant phenotype and genotype of the human androgen-independent cell line DU 145 and a subline derived from metastasis after orthotopic implantation in nude mice

To investigate the potential genetic changes underlying the progression of human hormone-resistant prostate cancer, we related chromosomal alterations of the DU 145 cell line and a subline isolated form a metastasis in an orthotopic model to tumorigenicity, metastasis and chemoresistance. In 15 mice 1 x 10(5) DU 145 cells were injected into the dorsal prostate. From a resulting paraaortic lymphnode metastasis, we isolated a subline (DU 145 MN1), which was injected into 15 nude mice. The sulforhodamine B (SRB) assay was used to analyze cell doubling time and the IC(50) of cisplatin and 5-fluorouracil for both cell lines. Cytogenetic characterization was performed with conventional karyotype analysis and fluorescence in situ hybridization (FISH). After orthotopic implantation of DU 145 cells tumorigenicity was 100% whereas only 2 mice revealed lymphnode metastases. In contrast, the take rate after implantation of DU 145 MN1 was 100%, with lymphnode metastases in 7 mice. The SRB assay revealed a 8-fold increased IC(50) for cisplatin and a 2.5-fold increase for 5-FU in DU 145 MN1 as compared to DU 145 cells. There was gain of a chromosome 8 and only two copies of chromosome 17 in the DU 145 MN1 cells as compared to the parental cell line. The emergence of an i(9)(q10) in addition to two normal chromosome 9 homologues in the DU 145 MN1 cell line was confirmed by FISH using a chromosome 9-specific painting probe. In summary, clonal evolution of the chromosomal changes following repeated orthotopic implantation, may assist in locating the genes involved in the progression and chemoresistance of human hormone-resistant prostate cancer.

Expression of the human telomerase reverse transcriptase is not related to telomerase activity in normal and malignant renal tissue

In this study, the association between telomerase activity and the expression of the human telomerase subunits human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT) in paired neoplastic and normal renal tissue samples was investigated. Reverse transcription (RT)-PCR on 20 tumor nephrectomy samples revealed that hTR was constitutively expressed both in cancer and normal tissue samples, independent of the telomerase activity status. Remarkably, using in situ hybridization, the expression levels of hTR were found to be markedly higher in the normal tissue than those in the tumors. Expression of hTERT mRNA by RT-PCR was observed in 90% of the cancer samples and, notably, also in 75% of the corresponding normal renal tissue samples. Because all of the normal tissue samples and some of the tumor samples were shown to be telomerase negative, our findings suggest that hTERT mRNA expression is not sufficient for telomerase enzyme activation. Furthermore, semiquantitative RT-PCR revealed equal or even higher hTERT mRNA expression levels in the telomerase-negative normal samples than in the corresponding cancer samples with telomerase activity, contradicting the assumption that a certain threshold level of hTERT mRNA is required for telomerase activation at least in renal tissue. It seems more likely, that other mechanisms, such as posttranscriptional modification of hTERT or inactivation of telomerase inhibitors, are involved in the acquisition of enzyme activity.

Novel amplification unit at chromosome 3q25-q27 in human prostate cancer

BACKGROUND

In prostate carcinoma, amplification of the genes c-MYC, Her2/NEU, and the androgen receptor gene has been documented, with gene amplification being related to progressive tumor growth. Recently, using comparative genomic hybridization (CGH), we provided evidence for DNA copy number gains at chromosome 3q25-q26 in prostate cancer [Sattler et al.: Prostate 39:79-86, 1999].

METHODS

In this study, additional prostatic tumors were evaluated by CGH to determine the frequency of DNA overrepresentation at 3q. Comparative PCR and Southern blot analyses were applied to determine whether known genes are involved in DNA copy number gains.

RESULTS

By CGH, DNA copy number gains, all of which involved chromosome region 3q25-q26, were disclosed in 50% of the prostate tumors analyzed. There was no evidence for high-level amplification. The analysis of 12 genes from 3q25-q27 by comparative PCR revealed amplification in 6 (35.3%) of 17 tumors tested. Amplification was detected for the genes IL12A, MDS1, SLC2A2, and SOX2, with coamplification of three genes in two tumors. IL12A was amplified as single gene in three tumors and in a subline of the DU145 cell line, SLC2A2 in one tumor.

CONCLUSIONS

Our studies revealed a novel amplification unit at 3q25-q27 in prostate carcinoma, with the genes IL12A, MDS1, SLC2A2, and SOX2 being located within the amplification unit. A common region of amplification was evident spanning the IL12A gene locus at 3q25-q26.2. Possibly, IL12A indicates an adjacent, till now unidentified gene which is important in the development of prostate cancer.

Long-term results following transurethral resection of the prostate

Two subsets of a single-center study population with benign prostatic hyperplasia (n(1) = 232; n(2) = 214) undergoing transurethral resection (TUR) of the prostate (TURP 1979 and 1995) entered a retrospective study designed to examine the long-term follow-up. The actual data were assessed with a patient-addressed questionnaire. Preoperative voiding patterns did not differ significantly; postoperative micturition revealed comparable results for both groups. Mortality and TUR syndrome rates were reduced to very low levels. The most significant improvement was found in blood transfusions. The postoperative incidence of urethral stricture (1.7 vs. 1.5%) or bladder neck contracture (2.7 vs. 2.4%) were low and did not alter significantly. Urinary incontinence changed for both collectives (11.4 vs. 3.3%). Urodynamic investigations revealed that all (n = 21) but 1 of the patients with TURP 1979 had the incontinence due to different bladder dysfunctions, but not because of postoperative stress incontinence. The questionnaire about the patient's actual contentment after TURP 1979 showed 79% of the patients still satisfied, 12% neutral and 9% dissatisfied with their micturition. Overall the patients reported a generally favorable view of TURP outcome in the long-term follow-up.

Androgen receptor expression, proliferation index and aneuploidy in tissue explant cultures derived prostate carcinoma cells co-cultivated on membranes

OBJECTIVES

An improved explant cell culture technique to avoid selection of prostatic adenocarcinoma cells toward diploid cells is described.

MATERIAL AND METHODS

21 prostatic carcinoma specimens which were obtained from 13 primary prostatic adenocarcinomas after radical prostatectomy were cultivated. Ploidy of the cells was monitored by fluorescence in situ DNA hybridization using the centromere-specific DNA probes pUC1.77, p alpha 7t1 and pY3.4. Phenotypic examination of androgen receptor (AR) expression was performed simultaneously with immunostaining by Ki-67 as proliferation marker to identify androgen-independent growing cell clones.

RESULTS

Interestingly, a high aneuploidy rate of the cell cultures was found with maintenance of aneuploidy in 18 (86%) of the 21 paraffin-embedded cancer tissue specimens with proved aneuploidy. Significant aneuploid cell populations were retained up to a maximum of ten transfer steps. During serial transfer of tumor pieces the aneusomic fraction slightly decreased as well as the percentage of AR/Ki-67-positive cells.

CONCLUSIONS

The presented in vitro model allows to study the proliferation of genetically abnormal cells with respect to hormone dependency in a paracrine situation.

[Molecular genetic principles of progression of malignant diseases]

During the past decade, the molecular mechanisms in the process of tumor progression, including metastasis and angiogenesis, have become better understood. Cancer metastasis consists of multiple, complex interacting steps. Each of these steps is crucial and limiting, since a failure to complete any one prevents the tumor cell from producing a metastasis. Detachment from the solid tumor by loosening the intercellular junctions and proteolysis of the extracellular matrix enables tumor cells to enter blood- and lymph vessels. The intravasation into the circulation is supported by the secretion of angiogenic factors, which induce degradation of the basal membrane in blood vessels. Adhesion to endothelial cells, extravasation from the circulation, and induction of angiogenesis are further essential steps for completing the metastatic process. Furthermore, it is well known that once a tumor cell has entered circulation, it will survive only by evasion of the immune system. The systematic identification of tumor antigens opens up new possibilities for immunotherapeutic approaches.

Detection of adeno-associated virus in human semen: does viral infection play a role in the pathogenesis of male infertility?

OBJECTIVE

To evaluate the occurrence of adeno-associated virus (AAV) DNA and/or human papillomavirus (HPV) DNA in the semen of infertile men as a possible factor in the pathogenesis of male infertility.

DESIGN

Descriptive pilot study.

SETTING

University-based diagnostic and research laboratory.

PATIENT(S)

Semen specimens were collected from 30 men with diagnosed infertility and from 8 control subjects.

INTERVENTION(S)

Diagnostic spermiograms were made and the semen specimens were separated into seminal fluid, nonspermatozoal cells, and spermatozoa using a Ficoll gradient technique.

MAIN OUTCOME MEASURE(S)

The presence of AAV and HPV DNA in the different fractions of the ejaculates from the infertile men and the control subjects was detected by polymerase chain reaction. Semen quality was analyzed according to World Health Organization guidelines.

RESULT(S)

Adeno-associated virus DNA was detected in 30% (9/30) of the ejaculates from the infertile men. No AAV DNA was found in the ejaculates from the 8 control subjects. In 8 of 9 samples, AAV DNA could be found only in the spermatozoal fraction of the specimen. Seven of 9 semen specimens that contained viral DNA also demonstrated oligoasthenozoospermia. Both AAV and HPV DNA was found in the spermatozoal fraction of 3 of 30 specimens.

CONCLUSION(S)

The data demonstrate for the first time the occurrence of AAV infection in human semen. Sperm motility seems to be affected by the presence of AAV.

Two different forms of p53 localized differently within cells of urogenital tumours

We analyzed the subcellular localization of p53 in prostate and bladder carcinoma cells. Using laser scanning microscopy and PAb1620, a monoclonal antibody recognizing the wildtype conformation of p53, and another monoclonal antibody directed against the mutant conformation of the protein (PAb240), we found two different subsets of p53 within the same cell. The wildtype subgroup was found in the nucleolus, whereas the mutant protein was confined to the nucleus. The results obtained by immunofluorescence were verified by Western blot analysis and immunoprecipitation. Thus, our findings demonstrate an unusual subcellular localization pattern of p53 in prostate and bladder cancer cells which may indicate another mechanism of inactivation of p53.

Focal intratumoral heterogeneity for telomerase activity in human prostate cancer

PURPOSE

The value of telomerase activity as a marker in clinical decision-making is closely related to how representative the analysis of a small tumor sample is for the whole tumor. We therefore evaluated the intratumoral distribution pattern of telomerase activity in prostatic carcinomas.

MATERIALS AND METHODS

From 50 prostate cancer patients treated with radical prostatectomy, telomerase activity was determined using the telomeric repeat amplification protocol (TRAP assay). Comparative analysis of at least two separate cancer areas from a single tumor was performed in 42 cases.

RESULTS

Telomerase activation has been demonstrated in 90% of the prostatic carcinomas. Focal intratumoral heterogeneity was found in 38.1% of the tumors with at least two different areas examined. Telomerase positivity of all samples from one given tumor was detected in 50%, telomerase negativity of all samples in 11.9%. A heterogeneous telomerase activity pattern was more frequently detected in tumors with a Gleason score < or = 7 than in those with a Gleason score > 7. Furthermore, there was an increase in the proportion of homogeneously telomerase-positive tumors with increase in severity of the Gleason score. The differences reached statistical significance. Telomerase activity was also detected in non-cancerous prostatic tissue samples.

CONCLUSIONS

Telomerase activation is nearly ubiquitous in prostatic carcinomas, although a heterogeneous telomerase activity pattern within tumors might produce a false-negative result in the telomerase activity assay. This limits the value of telomerase activity assays for diagnostic means. There is evidence for a shift from telomerase-negative prostate cancer tissue toward telomerase positivity during the progression process of prostate cancer. The relatively high proportion of telomerase-positive nonmalignant prostatic tissue samples argues against cancer-specificity of telomerase activation.

Comparative genomic hybridization reveals DNA copy number gains to frequently occur in human prostate cancer

BACKGROUND

Despite intensive studies over many years, there is only limited knowledge on the genetic changes underlying the development and progression of prostate cancer. No specific prostate carcinoma-related genetic event has yet been identified.

METHODS

In order to gain an overall view of regional chromosome gains and losses, comparative genomic hybridization (CGH) was used on a series of 16 prostate adenocarcinomas. Five benign prostate hyperplasia (BPH) samples were also evaluated.

RESULTS

Using CGH, chromosome alterations were observed in 81% of the prostate carcinomas analyzed. Gains of DNA copy numbers were found as the predominant imbalance, with chromosomes 3q (56%), 12q (56%), 8q (50%), Xq (50%), 4 (44%), 6q (44%), 5 (38%), 7q (38%), 9p (38%), and 13q (31%) being most frequently involved. Whereas DNA copy number gains comprised the whole chromosome or almost a whole arm of chromosomes 4, 5, 6, 9, and 13, the minimal overlapping regions on the other chromosomes were mapped to 3q25-q26, 8q21-q22, 12q13-q21, 7q31, and Xq22-q25. High-level amplifications were not found. Other chromosomes with nonrandom gains or losses of DNA sequences were discovered. The five BPH samples were found to be normal.

CONCLUSIONS

Amplification events at different chromosomal sites seem important in prostate cancer development. A new chromosome region with DNA copy number gains was identified on 12q, while other regions on 3q, 7q, 8q, and Xq were confirmed or narrowed down, indicating a possible role of known or putative protooncogenes in these regions for prostate cancer growth. Our low detection rate of DNA losses may to some part be explained by CGH immanent technical limitations.

[Telomerase in tumors: facts and perspectives]

Recent reports have indicated the ribonucleoprotein enzyme telomerase to play an important role in tumorigenesis. Activation of this enzyme is known to prevent progressive shortening of the end of the chromosomes, or telomeres, and hence to be critical in maintaining chromosomal integrity. The telomerase expressing cells require immortality. Supported by recent findings which suggest that telomerase activity is expressed in virtually all cancers but not in normal tissues, except those of the germline, hope grew up toward a potentially important new therapeutic target in the fight against cancer. An emerging hypothesis is that the inactivation of telomerase results in the death of immortal cells. If telomerase activation represents a tumor-specific feature, (gene) therapeutic applications would become most promising in regard to an effective anticancer therapy, possibly with limited side-effects. However, most recent studies report on telomerase activity to be also expressed in normal, non-neoplastic tissues as well as in non-neoplastic hyperproliferative lesions. The questions whether telomerase activity is tumor-specific or associated with (physiologic or pathologic) hyperproliferation is intriguing and remains to be clarified.