Gene Expression, DNA Methylation and Prognostic Significance of DNA Repair Genes in Human Bladder Cancer.

BACKGROUND/AIMS: This study investigated the gene expression and DNA methylation of selected DNA repair genes (MBD4, TDG, MLH1, MLH3) and DNMT1 in human bladder cancer in the context of pathophysiological and prognostic significance. METHODS: To determine the relationship between the gene expression pattern, global methylation and promoter methylation status, we performed real-time PCR to quantify the mRNA of selected genes in 50 samples of bladder cancer and adjacent non-cancerous tissue. The methylation status was analyzed by methylation-specific polymerase chain reaction (MSP) or digestion of genomic DNA with a methylation-sensitive restriction enzyme and PCR with gene-specific primers (MSRE-PCR). The global DNA methylation level was measured using the antibody-based 5-mC detection method. RESULTS: The relative levels of mRNA for MBD4, MLH3, and MLH1 were decreased in 28% (14/50), 34% (17/50) and 36% (18/50) of tumor samples, respectively. The MBD4 mRNA expression was decreased in 46% of non-muscle invasive tumors (Ta/T1) compared with 11% found in muscle invasive tumors (T2-T4) (P<0.003). Analysis of mRNA expression for TDG did not show any significant differences between Ta/T1 and T2-T4 tumors. The frequency of increased DNMT1 mRNA expression was higher in T2-T4 (52%) comparing to Ta/T1 (16%). The overall methylation rates in tumor tissue were 18% for MBD4, 25% for MLH1 and there was no evidence of MLH3 promoter methylation. High grade tumors had significantly lower levels of global DNA methylation (P=0.04). There was a significant association between shorter survival and increased expression of DNMT1 mRNA (P=0.002), decreased expression of MLH1 mRNA (P=0.032) and the presence of MLH1 promoter methylation (P=0.006). CONCLUSION: This study highlights the importance of DNA repair pathways and provides the first evidence of the role of MBD4 and MLH3 in bladder cancer. In addition, our findings suggest that DNMT1 mRNA and MLH1 mRNA expression, as well as the status of MLH1 promoter methylation, are attractive prognostic markers in this pathology.

Genomic instability analysis of urine sediment versus tumor tissue in transitional cell carcinoma of the urinary bladder.

Microsatellite alterations are a common feature of neoplastic cells. Our study aimed to compare the profile of microsatellite DNA alterations in tumor tissue and urine sediment at 12 selected microsatellite loci in transitional cell carcinoma of the bladder, and to determine which of the 12 markers or combination of markers has potential for the non-invasive diagnosis of bladder cancer. DNA alterations were examined using microsatellite markers on chromosomes 2p, 3p, 8p, 9p, 9q, 12q, 13q, 17p and 18q in 38 patients, including 12 with superficial Ta/T1 and 26 with muscle invasive T2-T4 bladder tumors. Microsatellite instability was a rare event in comparison with loss of heterozygosity and was related to a low rate of defects in mismatch repair genes. The sensitivity of microsatellite analysis was 75% (9/12) for Ta/T1 tumors and 69% (18/26) for T2-T4 tumors. Two tetranucleotide markers, D9S242 and D9S252, when combined, displayed microsatellite alterations in 59% (16/27) of microsatellite analysis-positive patients. DNA alterations were not detected in 21 non-tumor specimens. Twenty of 51 (39%) tumor DNA alterations were re-detected in urine sediments, and 7 alterations found in urine sediments were not found in the corresponding tumor specimens. No association was found between the DNA alterations and any of the prognostic parameters. However, the overall survival correlated with microsatellite alterations (P=0.04, log-rank test). These data suggest that markers at tetranucleotide repeats on chromosome 9q have particular diagnostic potential in bladder cancer. Moreover, microsatellite analysis is suitable for the selection of patients with a less favorable outcome.

[Photodynamic diagnosis and therapy of bladder cancer]. / Diagnostyka i terapia fotodynamiczna nowotworów pecherza moczowego.

High frequency of bladder cancer in polish population and relatively low sensitivity of cancer detection in early stages is a main reason for search for other, more sensitive diagnostic tests. Photodynamic diagnosis based on accumulation of photosensitizers, porphirin derived compounds emitting fluorescence in laser light is a promising tool for detecting of small or poorly differentiated neoplastic changes. On the other hand we can use photodynamic therapy when in laser light photosensitizers generate free oxygen radicals and destroy neoplastic tissue. Photodynamic therapy is a perfect tool in bladder cancer treatment especially in case of early stage or multicentric neoplastic changes that are difficult to resect in traditional endoscopic way.

Enhanced citrate synthase activity in human pancreatic cancer.

OBJECTIVES: Assuming that a high flux of carbohydrate is strictly connected with lipid synthesis in neoplastic cells, one can hypothesize that the activity of citrate synthase, which plays an important role in glucose to lipid conversion, is enhanced in pancreatic cancer. The aim of the present study was to verify this hypothesis. METHODS: The activity of citrate synthase (as well as lactate and glucose 6-phosphate dehydrogenases) was measured using tissue extract prepared from specimens (pancreatic cancer and control specimens taken from the adjacent pancreatic normal tissue) obtained from 24 patients with ductal carcinoma who underwent pancreatoduodenectomy or total pancreatomy. RESULTS: The average of citrate synthase activity in human pancreatic ductal carcinoma is significantly higher comparing with adjacent nonneoplastic tissue: 40.2 +/- 27.2 and 18.3 +/- 13.6 nmole/min/mg protein, respectively (P = 0.001). The lactate dehydrogenase and glucose 6-phosphate dehydrogenase activity in human pancreatic ductal carcinoma were also higher than in adjacent nonneoplastic tissues. CONCLUSION: It is likely that enhanced citrate synthase activity contributes to the conversion of glucose to lipids in pancreatic cancer providing substrate for membrane lipids synthesis.

Clinical implications of p53 mutation analysis in bladder cancer tissue and urine sediment by functional assay in yeast.

In the present study we correlate the p53 gene mutations in tumour tissue with urine sediment using a functional assay in yeast, and relate the p53 status to the outcome in a group of patients with transitional cell carcinoma of the bladder. The p53 mutations were found in three of 30 (10%) Ta/T1 tumour tissue samples and in two of 20 (10%) corresponding urine sediments. In the stage T2-T4 tumour p53 mutations were found in tumour tissues and urine sediments in 13 of 31 (42%) and in seven of 18 (39%) samples, respectively. In 80% (8/10) of cases, the p53 mutations found in tumour tissue were re-detected in urine sediment. Median follow-up was at 20 months. Disease recurred in 18 of the 61 patients (30%) with a median time of 5 months. In Ta/T1 tumours the frequency of recurrence was 37% (11/30) compared with 23% (7/31) of T2-T4 tumours. The 3-year overall survival (OS) was 82% (50/61). The p53 status was significantly associated with stage (P = 0.0077, two-sided Fisher's exact test), grade (P < 0.001) and lymph node involvement (P = 0.027). There was an association between the p53 mutations and shorter OS (P = 0.033; log-rank test); however in a multivariate analysis adjusted for stage, grade, lymph node status and age the p53 mutation was not an independent predictor of survival. There was no correlation of the p53 status with decreased disease-free survival (P = 0.8; log-rank test). The data presented indicate that the yeast functional assay is a useful method for p53 gene mutation analysis in tumour tissue and p53 mutation can be re-detected in urine sediment, but further validation of the assay in non-invasive screening for p53 mutations is needed.