Jürgen Serth

Expression of stem-cell factor and its receptor c-kit protein in normal testicular tissue and malignant germ-cell tumours

The proto-oncogene c-kit and its ligand stemcell factor (SCF) may play an important role in the development of normal and malignant testicular tissue. This study investigates the presence of SCF and c-kit protein in 32 orchiectomy specimens of patients with testicular cancer, in 5 specimens of normal testicular tissue and in three established non-seminomatous germ-cell cancer cell lines (H12.1, H32, 577ML) by an immunohistochemical approach. Out of 9 testicular cancer specimens classified as pure seminomas, 7 (78%) showed a strong immunohistochemical reaction for both SCF and c-kit protein on the surface of the tumour cells. Fourteen non-seminomatous germ-cell tumours composed of embryonal carcinoma were completely negative for both SCF and c-kit protein and only faint positivity was found in 6 tumours (26%). Differentiated teratomatous structures within the specimens of nonseminomatous tumours showed a strong immunohistochemical reaction for SCF and c-kit protein in 8 of 11 (73%) cases. All three testicular cancer cell lines showed only faint staining reactions for c-kit protein and none for SCF. No secretion of SCF by the three lines in vitro was detected. The addition of high concentrations of SCF (100 ng/ml) to the testicular cancer cell lines in culture conditions without fetal calf serum resulted in a 1.4 to 3-fold growth stimulation compared to cell growth in serum-free medium alone. This effect was not detectable when the cells were cultured in serum-containing media. In the normal testicular tissue the germ-cells displayed a strong immunohistochemical reaction for c-kit protein while SCF positivity was found at the tubular membrane and on the surface of Sertoli cells. The SCF/c-kit system may possess a regulatory function in normal testicular tissue by possibly providing the microenvironment necessary for spermatogenesis. With the development of testicular cancer, this regulatory system seems to be lost, particularly in non-seminomatous germ-cell tumours. A growthstimulatory effect of high concentrations of SCF on nonseminomatous testicular cancer cell lines can be detected only in culture conditions with serum-free media. The effects achievable by the combination of SCF with other growth factors need to be further studied, as well as the role of the c-kit/SCF regulatory system for normal spermatogenesis and its possible implications for the understanding and treatment of male infertility.

Quantitation of DNA Extracted after Micropreparation of Cells from Frozen and Formalin-Fixed Tissue Sections

Quantitation of DNA from microdissected fresh-frozen or paraffin-embedded tissue sections would be not only a valuable tool for ensuring optimum reaction conditions for many types of qualitative polymerase chain reaction (PCR) analyses, but also a prerequisite for any kind of subsequently performed genetic analyses aimed at the absolute quantitation of target sequences. The present study describes the quantitation of DNA after microdissection and extraction of cells with the PicoGreen fluorescence method. The limits of detection and of quantitative determination, respectively, have been determined by measuring dilutional series of three different DNA extractions, using either a medium-scale preparation from a solid tissue specimen or a known number of leukocytes or microdissected cells from frozen tumor sections. As corresponding limits of detection, 26, 24, and about 40 diploid genomes, and as limits of quantitative determination, 80, 73, and about 120 diploid genomes were obtained. Furthermore, it was shown that formalin fixation as well as hematoxylin staining of frozen sections with Delafields and Mayers alum or Weigerts iron hematoxylin before microdissection significantly diminishes the amount of extractable DNA and may lead to less reliable results, even of qualitative PCR analysis. In conclusion, the PicoGreen method allows precise quantitation of DNA corresponding to a minimum of about 120 diploid cells. It provides the basis for reliable qualitative analyses as well as the precondition for further quantitative genetic measurements from microdissected frozen or formalin-fixed and paraffin-embedded tissue sections.

Fibronectin 1 mRNA expression correlates with advanced disease in renal cancer

BackgroundFibronectin 1 (FN1) is a glycoprotein involved in cellular adhesion and migration processes. The aim of this study was to elucidate the role of FN1 in development of renal cell cancer (RCC) and to determine a prognostic relevance for optimal clinical management.Methods212 renal tissue samples (109 RCC, 86 corresponding tissues from adjacent normal renal tissue and 17 oncocytomas) were collected from patients undergoing surgery for renal tumors and subjected to total RNA extraction. Detection of FN1 mRNA expression was performed using quantitative real time PCR, three endogenous controls, renal proximal tubular epithelial cells (RPTEC) as biological control and the ΔΔCt method for calculation of relative quantities.ResultsMean tissue specific FN1 mRNA expression was found to be increased approximately seven fold comparing RCC and corresponding kidney control tissues (p < 0.001; ANOVA). Furthermore, tissue specific mean FN1 expression was increased approx. 11 fold in clear cell compared to papillary RCC (p = 9×10-5; Wilcoxon rank sum test). Patients with advanced disease had higher FN1 expression when compared to organ-confined disease (p < 0.001; Wilcoxon rank sum test). Applying subgroup analysis we found a significantly higher FN1 mRNA expression between organ-confined and advanced disease in the papillary and not in the clear cell RCC group (p = 0.02 vs. p = 0.2; Wilcoxon rank sum test). There was an increased expression in RCC compared to oncocytoma (p = 0.016; ANOVA).ConclusionsTo our knowledge, this is the first study to show that FN1 mRNA expression is higher in RCC compared to normal renal tissue. FN1 mRNA expression might serve as a marker for RCC aggressiveness, indicating early systemic progression particularly for patients with papillary RCC.

The Prognostic Value of p53 for Long-term and Recurrence- free Survival Following Radical Prostatectomy

In the present study, 76 specimens (T1-T4) from 76 randomly selected patients undergoing radical prostatectomy at Hannover University as well as in the Josef Hospital Regensburg (13 patients) between 1980 and 1992 for whom tissue sections for immunohistochemical investigation were available, were investigated for different biological and clinical characteristics as predictors for long-term and recurrence-free survival: age, depth of tumour infiltration, histological grade, lymph node status, as well as overexpression of the p53 protein (monoclonal antibody DO-1). After a median follow-up of 50 months, 6 of 18 patients (33%) with more than 20% of tumour cells stained positively for p53 died from tumour progression compared with 9 of 58 patients (16%) with less than 20% of tumour cells positive for p53. During univariate analysis, p53 overexpression (P = 0.011), histological grading (P = 0.009) and tumour stage (P = 0.024) were significant prognostic factors for survival, among which only p53 overexpression (P = 0.026) remained an independent significant predictor in multivariate analysis. Additionally, 18 of 66 patients (27%) with less than 40% positivity for p53 suffered tumour recurrence in contrast to 6 of 10 patients (60%) with more than 40% tumour cells exhibiting a positive staining reaction. In multivariate analysis, p53 overexpression was identified as the only prognostic parameter for recurrence-free survival (P = 0.005). Prospective studies are needed to confirm the independent prognostic potential of p53 overexpression in patients with localised prostate cancer. The availability of more refined prognostic factors should assist decision making regarding the value of radical prostatectomy versus a surveillance strategy for prognostically defined subgroups of patients.

p53 overexpression as a prognostic factor for advanced stage bladder cancer

Overexpression of the TP53 gene protein detected by immunohistochemistry appears to identify those patients with superficial bladder cancer at risk of the development of muscle invasive or metastatic disease. However, the role of p53 overexpression in patients with advanced or metastatic bladder cancer is not yet well established. In the present study, 44 specimens from 44 patients with advanced stage bladder tumours (T2-T4) undergoing radical cystectomy were investigated for different biological and clinical characteristics as possible prognostic factors: sex, age, depth of tumour infiltration, T-stage, histological grade, lymph node status, application of adjuvant systemic chemotherapy (MVAC), proliferative activity (staining for proliferating cell nuclear antigen (PCNA) by monoclonal antibody (PC10) as well as overexpression of the p53 oncoprotein (monoclonal antibody pAb 1801)). After a median follow-up of 22 months, 16 of the 23 patients (70%) with more than 40% of tumour cells stained positively for p53 (Group B) died from tumour progression compared with 7 of the 21 patients (33%) with less than 40% of tumour cells positive for p53. During univariate analysis, p53 overexpression (P = 0.008), staining for PCNA (> or = 80% of cells positive) (P = 0.01) and tumour stage (P = 0.01) were significant prognostic factors for survival, among which p53 overexpression (P = 0.023) as well as T-stage (P = 0.012) remained independent significant predictors during multivariate analysis. Prospective studies are needed to confirm the independent prognostic potential of p53 overexpression in patients with advanced bladder cancer. The availability of more refined prognostic factors should assist decision making regarding the value of more aggressive treatment options, such as adjuvant or neoadjuvant chemotherapy, for prognostically defined subgroups of patients.

Adiposity and Age are Statistically Related to Enhanced RASSF1A Tumor Suppressor Gene Promoter Methylation in Normal Autopsy Kidney Tissue

Age, adiposity, and smoking are risk factors for the development of renal cell carcinoma. Hypermethylation of the RAS association domain family 1A gene (RASSF1A) promoter belongs to the most frequently detected epigenetic alterations in human cancers including renal cell carcinoma. RASSF1A is functionally involved in cell cycle control in normal cells and depletion promotes a number of cellular changes increasing the risk for neoplastic growth. We investigated the hypothesis that age, modulated by the factors adiposity and anthracosis as a surrogate for smoking, is a predictor of RASSF1A promoter methylation in normal kidney tissue. Using a cross-sectional study design, we quantitatively analyzed RASSF1A methylation in 78 normal autopsy kidney tissues by quantitative combined bisulfite and restriction analysis and bisulfite sequencing, and statistically evaluated the degree of relative methylation for a relationship with the predictor age and study factors adiposity and state of anthracosis. Statistical analysis showed that age (regression analysis; P < 0.001), adiposity (univariate analysis; P = 0.016), and state of anthracosis (t test; P = 0.005) are each significantly associated with an increase of RASSF1A promoter methylation in normal kidney tissue. However, only age (P = 0.008) and adiposity (P = 0.008) were identified as independent predictors of RASSF1A promoter methylation using covariance analysis. This study provides statistical evidence that the common cancer risk factors age and adiposity enhance RASSF1A promoter methylation in nonmalignant kidney tissue. (Cancer Epidemiol Biomarkers Prev 2007;16(12):2526–32)

Caveolin 1 protein expression in renal cell carcinoma predicts survival

BackgroundCaveolae play a significant role in disease phenotypes such as cancer, diabetes, bladder dysfunction, and muscular dystrophy. The aim of this study was to elucidate the caveolin-1 ( CAV1) protein expression in renal cell cancer (RCC) and to determine its potential prognostic relevance.Methods289 clear cell RCC tissue specimens were collected from patients undergoing surgery for renal tumors. Both cytoplasmic and membranous CAV1 expression were determined by immunohistochemistry and correlated with clinical variables. Survival analysis was carried out for 169 evaluable patients with a median follow up of 80.5 months (interquartile range (IQR), 24.5 - 131.7 months).ResultsA high CAV1 expression in the tumor cell cytoplasm was significantly associated with male sex (p = 0.04), a positive nodal status (p = 0.04), and poor tumor differentiation (p = 0.04). In contrast, a higher than average (i.e. > median) CAV1 expression in tumor cell membranes was only linked to male sex (p = 0.03). Kaplan-Meier analysis disclosed significant differences in 5-year overall (51.4 vs. 75.2%, p = 0.001) and tumor specific survival (55.3 vs. 80.1%, p = 0.001) for patients with higher and lower than average cytoplasmic CAV1 expression levels, respectively. Applying multivariable Cox regression analysis a high CAV1 protein expression level in the tumor cell cytoplasm could be identified as an independent poor prognostic marker of both overall (p = 0.02) and tumor specific survival (p = 0.03) in clear cell RCC patients.ConclusionOver expression of caveolin-1 in the tumour cell cytoplasm predicts a poor prognosis of patients with clear cell RCC. CAV1 is likely to be a useful prognostic marker and may play an important role in tumour progression. Therefore, our data encourage further investigations to enlighten the role of CAV1 and its function as diagnostic and prognostic marker in serum and/or urine of RCC patients.

Alterations of the p53 Tumor Suppressor Gene in Carcinoma In Situ of the Testis

Carcinoma in situ (CIS) is regarded as the precursor of all histologic variants of testicular germ cell tumors except spermatocytic seminoma. For a variety of human malignancies, alterations of the p53 tumor suppressor gene have been identified as prognostic factors for a poor clinical course. Discussions of the occurrence of p53 gene alterations in testicular carcinoma have been controversial. Immunohistochemical detection of the p53 oncoprotein has been reported in four of eight CIS cell areas adjacent to mature teratoma. The majority of investigations have failed to demonstrate p53 gene alterations on the DNA level in testicular carcinoma specimens. However, the genetic analysis of testicular carcinoma is complicated by the histologic variety of tumors, resulting in a mixture of subtypes undergoing moleculargenetic analysis. In the present study, CIS cells identified in normal testicular tissue adjacent to different testicular tumors were examined for alterations of the p53 tumor suppressor gene. The authors believed that the detection of p53 alterations in CIS of the testis would not only support the idea of malignant potential in CIS but might also demonstrate the involvement of the p53 tumor suppressor gene in the development of germ cell cancers.

DNA methylation biomarkers predict progression-free and overall survival of metastatic renal cell cancer (mRCC) treated with antiangiogenic therapies.

VEGF-targeted therapy increases both the progression-free (PFS) and overall survival (OS) of patients with metastasized renal cell cancer (mRCC). Identification of molecular phenotypes of RCC could improve risk-stratification and the prediction of the clinical disease course. We investigated whether gene-specific DNA hypermethylation can predict PFS and OS among patients undergoing anti-VEGF-based therapy. Primary tumor tissues from 18 patients receiving targeted therapy were examined retrospectively using quantitative methylation-specific PCR analysis of CST6, LAD1, hsa-miR-124-3, and hsa-miR-9-1 CpG islands. PFS and OS were analyzed for first-line and sequential antiangiogenic therapies using the log rank statistics. Sensitivity and specificity were determined for predicting first-line therapy failure. Hypermethylation of CST6 and LAD1 was associated with both a shortened PFS (log rank p = 0.009 and p = 0.004) and OS (p = 0.011 and p = 0.043). The median PFS observed for the high and low methylation groups of CST6 and LAD1 was 2.0 vs.11.4 months. LAD1 methylation had a specificity of 1.0 (95% CI 0.65–1.0) and a sensitivity of 0.73 (95% CI 0.43–0.90) for the prediction of first-line therapy. CST6 and LAD1 methylation are candidate epigenetic biomarkers showing unprecedented association with PFS and OS as well as specificity for the prediction of the response to therapy. DNA methylation markers should be considered for the prospective evaluation of larger patient cohorts in future studies.

GATA5 CpG island methylation in renal cell cancer: a potential biomarker for metastasis and disease progression.

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