[Molecular biology in bladder cancer]

Investigation of the association between mitochondrial DNA and p53 gene mutations in transitional cell carcinoma of the bladder

Bladder carcinoma is the most common malignancy of the urinary tract. The major aim of the present study is to investigate the association between mitochondrial DNA (mtDNA) and p53 gene mutations in bladder carcinoma. A total of 30 patients with transitional cell carcinoma and 27 controls were recruited for the study. Bladder cancer tissues were obtained by radical cystectomy or transurethral resection. Genomic DNA was extracted from peripheral blood. mtDNA and p53 genes were amplified by polymerase chain reaction and sequenced directly. A total of 37 polymorphisms were identified, among which, 2 mutations were significant in the patient group, and 1 mutation was significant in the control group. Additionally, 5 different moderate positive correlations between mtDNA mutations and 3 different positive correlations between p53 gene and mtDNA mutations were detected. The high incidence of mtDNA and p53 gene mutations in bladder cancer suggests that these genes could be important in carcinogenesis.

Constitutional and occupational risk factors associated with bladder cancer

OBJECTIVE

Bladder carcinoma (BC) is the fourth most common type of cancer in males from Western countries, with primary prevention an important healthcare challenge. We review the associated constitutional and occupational risk factors (RF), with greater or lesser scientific evidence, in the aetiology of BC.

MATERIAL AND METHODS

Literature review of the last 25 years of the constitutional and occupational RF associated with BC, conducted on MedLine, CancerLit, Science Citation Index and Embase. The search profiles were Risk factors/Genetic factors/Genetic polymorphisms/Epidemiology/Occupational factors and Bladder cancer.

RESULTS

The main RF were a) age and gender (diagnosed at age 65 and over, with a 4:1 ratio of males to females); b) race, ethnicity and geographic location (predominantly in Caucasians and in Southern European countries); c) genetic (N-acetyltransferase-2 and glutathione s-transferase M1 gene mutations, which significantly increase the risk for BC); d) occupational, which represent 5%-10% of BC RF; and f) occupations with high BC risk, such as aluminium production, the manufacture of dyes, paints and colourings, the rubber industry and the extraction and industrial use of fossil fuels.

CONCLUSIONS

BC is the end result of the variable combination of constitutional and environmental RF, the majority of which are unknown. The most significant constitutional RF are related to age, gender, race, ethnicity geographic location and genetic polymorphisms. The main occupational RF are those related to aromatic amines and polycyclic aromatic hydrocarbons.

Implications of p53 gene mutations on patient survival in transitional cell carcinoma of the bladder: a long-term study

OBJECTIVE

To determine the prognostic value of p53 gene mutations and P53 overexpression for predicting the incidence of recurrence, progression and long-term survival of patients with transitional cell carcinoma (TCC) of the bladder.

METHODS

Prospective cohort study with 94 consecutive patients diagnosed and treated for TCC. DNA was obtained from tumor tissue to perform PCR-SSCP of p53 exons 5-9, with automatic sequencing of any mutated samples. Immunohistochemistry using anti-human P53 monoclonal antibody was also performed. Survival was analyzed and the survival curves compared (Mantel-Haenszel). Lastly, a Cox proportional hazards model was constructed.

RESULTS

Mutations were found in 46.8% of samples, with 61.8% in infiltrating tumors. Exon 8 was involved in 42.3%. P53 overexpression (cutoff > or =20%) was found in 52.1%. Mean follow-up was 44.1 months; 43.6% had died by the end of this period. Mean survival was lower in patients with exon 8 mutations (38.4 months), compared with patients without this exon mutated (P = 0.016). There were no differences in patient survival based on positive or negative immunohistochemistry (cutoff > or =20%), although survival was lower in patients with a percentage higher than 50% of antibody-stained cells (P = 0.02). In the Cox analysis, tumor stage, pM stage, and interaction between stage > or =pT2 and mutated p53 gene were independent risk factors, with a 6.13-fold risk of death in these patients (P = 0.019). The number of tumors, nuclear grade, pTa stage, and the interaction between GI degree and nonmutated p53 gene remained in the Cox model for superficial tumors, such that these patients had a lower risk of recurrence or progression (P = 0.008).

CONCLUSIONS

Alterations in the p53 gene may be indicative of poorer prognosis and greater recurrence in patients with urothelial bladder tumor, in particular, the presence of mutations in exon 8 and a greater percentage of stained cells in the immunohistochemistry. Nevertheless, the classic prognostic factors (primarily, pTNM stage) should still be considered the most useful factors for follow-up of these patients.

p53 Gene mutations in superficial bladder cancer

OBJECTIVES

To assess the presence of p53 gene mutations in superficial tumors of the urinary bladder (transitional cell carcinoma) and their relationship to classic prognostic factors for cancer recurrence and progression. To analyze the implication of these mutations on the P53 protein structure.

MATERIALS AND METHODS

Observational, cross-sectional study of 90 consecutive patients, 60 with superficial transitional cell carcinoma (pTa and pT1) and 30 without neoplastic disease (control group). Samples of bladder tumor and control normal mucosa were analyzed by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) to detect p53 mutations in exons 5-9. Automatic sequencing was used to characterize the mutations and their effect on the P53 protein was analyzed. Bivariate analysis was used to assess the association with other prognostic factors.

RESULTS

PCR-SSCP found no mutations in any control group patient, whereas 38.3% of patients with superficial transitional cell carcinoma had one or more mutations in the exons analyzed. Thirty mutations were sequenced; all were point mutations and 86.67% were considered relevant for the P53 structure. A total of 93.3% of the mutations were located in highly conserved regions and 73.3% in mutational hot spots. The highest cell differentiation grades and pT1 stage were associated with a higher incidence of p53 gene mutations. Previous recurrences and other tumor-related histological variables were not associated with a higher percentage of mutations.

CONCLUSION

Mutations at p53 did not appear in healthy bladder mucosa and were significantly more frequent in pT1 and high-grade (G-II and G-III) tumors. All mutations detected were point mutations and most caused considerable P53 structural abnormalities, implying major repercussions on P53 function. These data suggest that certain p53 mutations may have prognostic value, even though they were not associated with other classic recurrence and tumor progression parameters. Future analyses of the progress of patients with superficial bladder transitional cell carcinoma and mutated p53 will help clarify this aspect.

[Comparative study of the expression of p53, Ki-67, bcl-2 and CK20 in superficial transitional carcinoma of the bladder: correlation with recurrence, histological grade, and clinical stage]

OBJECTIVE

We examined the presence of p53, Ki-67, bcl-2 and CK20, as detected by immunohistochemistry, and correlated with the classic variables (grade, stage and recurrence).

MATERIAL AND METHOD

The authors evaluated 57 superficial transitional cell carcinomas. Biopsy specimens examined included non recurrent transitional cell carcinomas (n = 36) and recurrent transitional cell carcinomas (n = 21). Association of bcl-2, p53, Ki-67 y CK20 index immunoreactivity with tumor grade, clinical stage and tumor recurrence was examined.

RESULTS

Ki-67 and p53 expression were related to the degree of differentiation and recurrence of the disease. bcl-2 and CK20 were not correlated with grade, stage and recurrence of the disease.

CONCLUSIONS

Positivity for Ki-67 and p53 increase with grade of the disease. P53 and Ki-67 are predictors of tumor recurrence for patients with superficial transitional cell carcinoma.

[The role of tumor markers in prognosing transitional bladder cancer]

PURPOSE

Review the literature on tumor markers used for prognosis of transitional bladder cancer. The existing problems regarding grading and local staging of these tumors are also discussed.

METHODS

The published literature on transitional bladder cancer markers was identified using a Medline search and critically analysed.

RESULTS

There are significant interobserver differences in grading. There is a new grading system. There are also problems in local staging and low correlation between clinic stage and pathologic stage. Major tumor markers studied for prognosis of transitional bladder cancer are: flow cytometry, kariocytometric study, oncogenes (p53, bcl-2, Her2/Neu or c-erbB2), chromosomic alterations (chromosomes 9, 7 and 17), proliferation markers (Ki-67, MIB-1), cyclin-dependent kinases and its inhibitors (cyclin D1, cyclin E, p21Wafl, p27Kipl), vascular endothelial growth factor, other growth factors (fibroblastic, epidermal, hepatocyte, platelet-derived), metalloproteinases, cell adhesion molecules, and others.

CONCLUSIONS

At present, there are no prognostic markers for bladder cancer that are superior to conventional grading and staging, despite its imperfections. Standarization of assay methods in bladder tumor markers is needed to permit more conclusive and reproducible results and become a clinic tool. Controversy resulting from several studies make the meaning of some putative prognostic markers in transitional bladder cancer questionable.

[The role of tumor markers in urologic consultation for screening, diagnosis, and follow-up of bladder cancer]

PURPOSE

Review the tumor markers for screening and diagnosis of transitional cell carcinoma of the bladder.

METHODS

The published literature on bladder cancer markers was identified using a MEDLINE search and critically analyzed. The sensitivity and specificity of the various markers were compared.

RESULTS

Conventional non-invasive methods for diagnosis (symptoms and urine cytology) and for screening and follow-up of transitional cell carcinoma of the bladder are not very sensitive and must not be considered sufficient. Some tumor markers seem to be a good alternative to the routine urinary cytology.

CONCLUSION

The role of tumor markers for screening and follow-up of bladder tumors as an alternative to cytology deserve consideration. In the future, more sensitive and specific markers may replace routine cystoscopy.