Frank Christoph

Quantitative analysis of survivin mRNA expression in urine and tumor tissue of bladder cancer patients and its potential relevance for disease detection and prognosis

Suppression of apoptosis may favor the onset and progression of cancer. Survivin is an inhibitor of apoptosis that has been suggested as a novel diagnostic/prognostic marker of bladder cancer. In this study, survivin mRNA expression was measured by a sensitive real‐time PCR assay in tumor tissue and urine from bladder cancer patients and assessed for its potential diagnostic and prognostic relevance. Specimens from 53 patients with bladder transitional cell carcinoma (TCC) were analyzed, the controls being normal urothelial tissues (n = 14) and urine from benign disease patients (n = 22) and healthy individuals (n = 14). Survivin transcripts were commonly detected in tumor tissues, but not in normal urothelium, and increasing mRNA levels correlate with progressing pathologic stage (p = 0.001) and grade categories (p < 0.004). Higher levels of expression were associated with a reduced time to recurrence in noninvasive TCCs (p = 0.027, log‐rank test) and a trend toward shorter disease‐free survival in muscle‐invasive tumors (p = 0.067). Urinary survivin analysis detects TCC with higher sensitivity (68.6%) and equal specificity (100%) when compared with cytology (31.4% and 97.1%). Our results indicate that tissue levels of survivin mRNA predict disease‐free survival in noninvasive TCC and may have a role in bladder cancer progression. When analyzed by RT‐PCR in urine, survivin is a highly specific biomarker for TCC detection.

Regularly methylated novel pro-apoptotic genes associated with recurrence in transitional cell carcinoma of the bladder

Epigenetic silencing of tumor suppressor genes by promoter hypermethylation has been shown for a variety of genes in bladder cancer. Various p53 target genes have been investigated, but only few demonstrated promoter hypermethylation when semiquantitative detection methods were applied. To address to the question whether promoter methylation of novel p53 effector genes is a common event in transitional cell carcinoma of the bladder, we selected the p53 target genes apoptotic protein‐activating factor (APAF‐1), Caspase 8 (CASP‐8), death‐associated protein kinase, (DAPK‐1) and insulin‐like growth‐factor‐binding protein‐3 (IGFBP‐3), performing quantitative methylation‐specific real‐time PCR. The individual level of methylation (normalized index of methylation) was correlated with clinicopathological features as well as the biological behavior of the superficial and muscleinvasive tumors. Tissue was obtained from 110 tumor patients and 20 patients without urological malignancy. The median follow‐up of the tumor patients was 52 months. Hypermethylation of the promoter region in tumor specimens was common for APAF‐1 (100%), DAPK‐1 (74%) and IGFBP‐3 (66%), but not for CASP‐8 (3.6%). It was seen less frequently and with undetectable or low methylation levels in the normal urothelium group. The APAF‐1 methylation levels significantly correlated with tumor stage and tumor grade. The APAF‐1 and IGFBP‐3 methylation levels were able to separate tumors with higher recurrence risk from low‐risk tumors in nonmuscleinvasive and muscleinvasive tumors. In multivariate analysis, APAF‐1 and IGFBP‐3 methylation levels were independent prognostic markers for recurrence in superficial bladder tumors. This study provides new insights into the role of promoter methylation of selected p53 target genes. The extent of promoter methylation of specific genes offers additional prognostical information and is associated with the outcome in patients with nonmuscleinvasive and muscleinvasive bladder cancer.

Promoter Hypermethylation Profile of Kidney Cancer with New Proapoptotic p53 Target Genes and Clinical Implications

Purpose: Risk stratification of renal cell carcinoma is based on the histopathologic classification. Promoter hypermethylation as a mechanism of gene inactivation in renal cell carcinoma has been shown for only a small number of genes. We examined the usefulness of quantitative methylation analysis with a new set of p53 target genes for determining the clinical outcome and aggressiveness of the tumor disease. Experimental Design: The genes selected were APAF-1, CASPASE-8, DAPK-1, IGFBP-3, and PML. The tissue samples analyzed were taken from tumor specimens obtained from 90 consecutive patients with clear cell renal carcinoma and from 20 normal kidney specimens. Quantitative methylation analysis of CpG sites in the promoter region was done by methylation-specific real-time PCR and the normalized index of methylation (NIM) was determined for each sample. Results: Hypermethylation of the promoter region was common for APAF-1 (97%) and DAPK-1 (41%) but not for IGFBP-3 (3%), PML (3%), or CASP-8 (0%). The tumor patients had a median follow-up of 55 months. A correlation was found between the methylation level of APAF-1 and tumor size and nodal status, but not for tumor stage, grade, and age of patient. Kaplan-Meier analysis was able to identify patients with a higher risk of recurrence and tumor-related death by using APAF-1 (≥56% NIM) and DAPK-1 (≥10% NIM) methylation levels. In multivariate analysis, APAF-1 and DAPK-1 methylation levels were independent prognostic markers for metastatic disease and death from renal cell carcinoma. Conclusions: Our findings indicate that promoter hypermethylation of APAF-1 and DAPK-1 is a marker of aggressive renal cell carcinoma and provides independent prognostic information on disease outcome.

Expression parameters of the polycomb group proteins BMI1, SUZ12, RING1 and CBX7 in urothelial carcinoma of the bladder and their prognostic relevance.

Background: The Polycomb group (PCG) proteins are epigenetic transcriptional repressors involved in the control of cellular proliferation and oncogenesis. This study aimed at examining whether mRNA tumor levels of the PCG family members BMI1, SUZ12, RING1, and CBX7 relate to histopathological parameters in urothelial carcinomas of the bladder and whether they may provide prognostic information following tumor resection. Methods: The relative gene expression of BMI1, SUZ12, RING1, and CBX7 was analyzed by real-time RT-PCR in tumor tissue obtained from 93 patients with urothelial carcinoma of the bladder undergoing surgical treatment. Expression data was correlated with pathological variables and outcome. Results: PCG family members BMI1, SUZ12, RING1, and CBX7 are commonly expressed in urothelial carcinomas of the bladder. The relative CBX7 mRNA expression levels gradually decreased from superficial (pTa) to invasive (pT1) and finally to muscle-invasive (≥pT2) tumors (p = 0.008). Furthermore, CBX7 expression was statistically significantly correlated with tumor grade (p = 0.04). No correlation of mRNA levels with histopathological tumor features or tumor recurrence was observed for the other PCG components investigated. Conclusion: Expression levels of CBX7 inversely correlate with the progression of tumor stage and grade in urothelial carcinomas of the bladder, suggesting that downregulation of CBX7 indicates aggressive urothelial carcinoma phenotype.

Expression of the Apoptosis Inhibitor Livin in Renal Cell Carcinomas: Correlations with Pathology and Outcome

Livin has recently been identified as a member of the inhibitor of apoptosis family expressed in several types of cancer but not in most benign tissues. Expression levels of livin were associated with prognosis in various malignancies, but livin expression and its prognostic relevance have not been evaluated in renal cell carcinomas (RCC). In a cohort of 152 RCC patients, we analyzed the relative expression of livin and its splicing variants by real-time RT-PCR and Western blot in tumor and adjacent normal renal tissue specimens. Livin expression was detected in 59 (38.8%) of 152 RCC specimens but in none of the normal samples. Both splicing variants were present in the livin-positive RCC specimens. Livin expression levels did not correlate with pathological or clinical parameters and were not predictive of patient outcome. Our findings suggest that livin expression in RCC is not of prognostic relevance. Further studies to clarify the role of livin expression in RCC and its potential value as a target for immune-mediated tumor destruction are warranted.

Quantitative evaluation of telomerase subunits in urine as biomarkers for noninvasive detection of bladder cancer

The aim of our study was to prospectively evaluate the potential diagnostic value and clinical applicability of quantitative analysis of telomerase subunits gene expression in urine for noninvasive detection of bladder cancer. Expression levels of human telomerase reverse transcriptase (hTERT) and human telomerase RNA (hTR) were analyzed by real‐time reverse transcriptase polymerase chain reaction (RT‐PCR) in urine samples from 163 subjects with bladder cancer and 237 controls (163 individuals with benign genitourinary diseases; 74 healthy subjects). The sensitivity, specificity and optimal cutoffs were determined and compared to the corresponding values obtained by voided urine cytology. Quantitative urinary hTR analysis detects bladder cancer with an overall sensitivity of 77.0%, whereas hTERT analysis reached a sensitivity of 55.2%. The majority of undetected tumors were small, low‐grade pTa lesions. Both hTR and hTERT proved to be significantly more sensitive than cytology (34.5%; p < 0.001). Specificities for hTR, hTERT and cytology were 72.1%, 85.0% and 92.7%, respectively, in the total study population and 96.9%, 89.2% and 100%, respectively, in healthy subjects. Higher diagnostic accuracy was achieved by hTR than by hTERT analysis (p < 0.05). The specificity of hTR increased to 85.0% in the total population if urinary leukocyte contamination was excluded. These data suggest that quantitative hTR analysis is the most accurate telomerase‐based test for bladder cancer detection and has the potential to replace cytology as a noninvasive biomarker for disease diagnosis and follow‐up.

Expression parameters of the inhibitors of apoptosis cIAP1 and cIAP2 in renal cell carcinomas and their prognostic relevance

The expression of the inhibitor of apoptosis (IAP) family members cIAP1 and cIAP2 have been shown to be altered in various cancer entities. This study was done to characterize the tumor‐related expression profile of cIAP1 and cIAP2 in patients with renal cell carcinomas (RCC) and to evaluate its potential predictive value after curative resection. Expression of cIAP1 and cIAP2 was analyzed by real‐time RT‐PCR in RCC and corresponding normal tissue samples obtained from a cohort of 127 RCC patients (median follow‐up: 48 months) undergoing surgical treatment. Expression data was correlated to histopathological variables and outcome. Overexpression of cIAP1 and cIAP2 occurred in most RCC specimens (p < 0.001), but 20% of the patients had lower cIAP levels in malignant than in normal tissue. The cIAP1 expression correlated with the tumor stage, levels being higher in pT1 tumors than in advanced pathological stages (p = 0.002). Decreased cIAP1 expression in RCC relative to paired normal samples predicted an abbreviated time to recurrence (hazard rate 2.96; 95% CI: 1.23–7.09) and tumor‐specific survival (hazard rate 2.78; 95% CI: 1.22–6.38) irrespective of the tumor stage and grade. The prognostic effect of cIAP1 was most pronounced in patients with pT3 disease (log rank test p = 0.001). The results of uni‐ and multivariate analysis suggest a prognostic value of cIAP1 expression for RCC patients, downregulation indicating an aggressive, potentially lethal phenotype.

Epigenetic silencing of the putative tumor suppressor gene testisin in testicular germ cell tumors

PurposeTestisin, a serine protease abundantly expressed only in normal testes, is thought to be a tumor suppressor gene silenced by aberrant methylation in testicular germ cell tumors (TGCT). This study aimed at identifying the CpG sites relevant for testisin gene silencing when methylated and evaluating the potential of aberrant methylation as a biomarker in TGCT.MethodsBisulfite sequencing and subsequent real-time RT-PCR were carried out in germ cell tumor cell lines and a cervical carcinoma cell line to reveal CpG sites implicated in testisin gene silencing. The normalized index of methylation (NIM) and the relative gene expression (RGE) were calculated in 33 TGCT and 19 normal testicular tissue samples by quantitative methylation-specific PCR (QMSP) and real-time RT-PCR.ResultsCpG sites in the 5′untranslated region proved to be relevant for testisin gene silencing when methylated. Targeting these CpG sites by QMSP, we demonstrated that the median NIM was 8.6 times higher in the TGCT group than in normal testicular samples. This was associated with a median 23.6 times lower RGE in the TGCT probes. Non-seminomas had a significantly higher NIM than seminomas, but RGE was downregulated to comparable levels in both subgroups. QMSP was highly sensitive and distinguished TGCT from normal samples with excellent specificity.ConclusionsOur results demonstrate for the first time that aberrant methylation of specific CpG sites near the transcription initiation site is an important factor in testisin gene silencing in TGCT.

Quantitative real-time RT-PCR of CD24 mRNA in the detection of prostate cancer

BackgroundGene expression profiling has recently shown that the mRNA for CD24 is overexpressed in prostate carcinomas (Pca) compared to benign or normal prostate epithelial tissues. Immunohistochemical studies have reported the usefulness of anti-CD24 for detecting prostate cancer over the full range of prostate specimens encountered in surgical pathology, e.g. needle biopsies, transurethral resection of prostate chips, or prostatectomies. It is a small mucin-like cell surface protein and thus promises to become at least a standard adjunctive stain for atypical prostate biopsies. We tested the usefulness of real-time RT-PCR for specific and sensitive detection of CD24 transcripts as a supplementary measure for discriminating between malignant and benign lesions in prostatic tissues.MethodsTotal RNA was isolated from snap-frozen chips in 55 cases of benign prostatic hyperplasia (BPH) and from frozen sections in 59 prostatectomy cases. The latter contain at least 50% malignant epithelia. Relative quantification of CD24 transcripts was performed on the LightCycler instrument using hybridization probes for detection and porphobilinogen deaminase transcripts (PBGD) for normalization.ResultsNormalized CD24 transcript levels showed an average 2.69-fold increase in 59 Pca-cases (mean 0.21) when compared to 55 cases of BPH (mean 0.08). This difference was highly significant (p < 0.0001). The method has a moderate specificity (47.3%) but a high sensitivity (86.4%) if the cutoff is set at 0.0498. CD24 expression levels among Pca cases were not statistically associated with the tumor and lymph-node stage, the grading (WHO), the surgical margins, or the Gleason score.ConclusionThe present study demonstrates the feasibility of quantitative CD24 RNA transcript detection in prostatic tissues even without previous laser microdissection.

EZH2 Polycomb Transcriptional Repressor Expression Correlates with Methylation of the APAF-1 Gene in Superficial Transitional Cell Carcinoma of the Bladder

The EZH2 gene controls methylation of various EZH2 target promoters. The APAF-1, DAPK-1 und IGFBP-3 genes are frequently methylated in bladder cancer, and methylation of these genes is found in more aggressive tumor types. The aim of our study was to investigate a potential link between EZH2 mRNA expression and the extent of APAF-1, DAPK-1 and IGFBP-3 methylation in urothelial transitional cell carcinoma (TCC) and to correlate the data with histopathological parameters and follow-up data. EZH2 mRNA expression was measured by real-time reverse transcription polymerase chain reaction, and the methylation analysis was performed using methylation-specific real-time polymerase chain reaction. Tissue specimens were obtained from 35 patients with TCC. EZH2 mRNA expression was detected in all tumor specimens investigated. The EZH2 expression levels correlated well with the differentiation grade of the tumor specimens (p = 0.03), and the APAF-1 methylation correlated with tumor stage (p = 0.0001) and grade (p = 0.004). Matched pair analysis demonstrated a statistically significant correlation between elevated EZH2 mRNA expression and higher methylation levels of APAF-1 in superficial (p = 0.024) and well- differentiated (p = 0.04) TCC. In patients with recurrent TCC, APAF-1 and IGFBP-3 methylation levels were significantly higher (p = 0.03 and p = 0.01, respectively), which was not observed when EZH2 mRNA expression or DAPK-1 methylation levels were related to the clinical outcome. In conclusion, our data show that EZH2 expression and APAF-1 methylation are related to tumor progression and invasiveness. Moreover, these data present first evidence that APAF-1 methylation is related to transcriptional activity of EZH2 expression in early-stage tumor disease of the bladder.