Thomas Zwergel’s research while affiliated with Saarland University and other places

We retrospectively reviewed the outcome in our patients with prostate cancer and regional positive lymph nodes who underwent prostatectomy. Between January 1984 and December 2002, 147 men were found to have local lymph node metastases after surgery, of whom 135 underwent further androgen ablation, including 88% within 6 weeks after prostatectomy. We especially determined overall, cancer specific and progression-free survival rates. Median patient age was 63.2 years (range 46 to 75 years). Postoperative followup was up to 214 months (median 41.9). There was 1 death secondary to surgery. To date 49 patients (33.3%) had disease progression, including 6 with a prostate specific antigen increase later than 100 months after surgery, and 36 (24.5%) died, including 22 of prostate cancer and 14 of other causes. Overall and cause specific survival probabilities at 5, 10 and 15 years were 76.6% and 86.5%, 60.1% and 73.7%, and 47.2% and 57.9%, respectively. Median overall survival was 144 months and median cancer specific survival was greater than 145 months. Overall progression-free probabilities at 5, 10 and 15 years were 72.7%, 49.8% and 31.6%, respectively. Biochemical progression-free survival rates were 77.4% after 5, 53.0% after 10 and 33.7% after 15 years. Since three-quarters of our patients were likely not to die of prostate cancer within the 10 years after surgery despite histological evidence of lymph node metastases, radical prostatectomy with or without hormonal therapy is a viable option for patients with local lymph node involvement, particularly in view of long-term survival.

We recently reported on a prostate cancer progression model which was based on repeated orthotopic implantation of human prostate cancer cell lines into athymic nude mice leading to an increase of tumor cell aggressiveness. To assess progression-associated clonal evolution of genotypic changes, we now performed comparative cytogenetic characterization of the original cell lines DU145 and PC3 with derived sublines DU145MN1 and PC3-N. Cell line PC3-125-1L, isolated from a lung metastasis after subcutaneous inoculation of PC3 into nude mice, was included in the study. Whole-genome analysis was performed using spectral karyotyping and comparative genomic hybridization. Fluorescence in situ hybridization was used to assess amplification of selected genes, which are supposed to play a role in prostate cancer progression. Differences in the genetic constitution between parental cell lines and sublines involved gains of genetic material at 2q, 5q, 12p/q, and 18p as well as losses at 6p, 7q, 17p, 18q, and 22q. Loss of 17p in DU145MN1 and high-level amplification of MYC in PC3-125-1L resulted in loss of p53 expression and upregulation of Myc expression, respectively, as was assessed by Western blotting. Thus, the nude mice model is very useful to follow clonal evolution of genetic changes during increase of prostate cancer aggressiveness and possibly to clone genes associated with the progression of prostate cancer.

True mucinous adenocarcinoma of the prostate is a rare morphological variant, accounting for approximately 0.4% of the prostatic adenocarcinomas. Although amounts of mucin confined in the lumina can be demonstrated in a great number of prostatic carcinomas, only those with at least 25% of the resected tumor composed of lakes of extracellular mucin should be classified as true mucinous.1 The impact of the mucinous growth pattern on the clinical course is unclear. Whereas many investigators have suggested that the mucinous variant is less aggressive than the nonmucin producing adenocarcinoma of the prostate, others have observed no difference in clinical symptoms and metastatic behavior.2 For colonic carcinoma it has been demonstrated that extracellular mucin production is an outstanding feature of those tumors revealing microsatellite instability.3 Despite a strong tendency for poor differentiation, microsatellite instability positive colonic carcinomas seem to have a relatively favorable clinical outcome with a reduced likelihood of metastases. To our knowledge no data on molecular changes in the phenotypically related mucinous tumors of the prostate gland are available yet. We report a case of a mucinous adenocarcinoma of the prostate with poor clinical outcome. Molecular analyses revealed high frequency microsatellite instability, indicating a defective mismatch repair to be related to the development of the mucinous prostatic tumor type. CASE REPORT

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]. 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. 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. 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.

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. Prostate 45:207–215, 2000. © 2000 Wiley‐Liss, Inc.

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.

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. 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. 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. 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.