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Published on: October 30, 2013
Molecular mechanisms in urinary bladder carcinogenesis
D Volanis1, G Papadopoulos, K Doumas
1Department of Urology, "Asklipieio" General Hospital, Voula, Athens, Greece.
Abstract:
Urinary bladder cancer accounts for approximately 5% of all newly diagnosed malignancies in the developed world. Smoking, occupational exposure and dietary factors constitute the most important exogenous risk factors for bladder carcinogenesis. Yet, individuals with seemingly equal exposure to environmental carcinogens develop bladder cancer in an unpredictable manner. This is probably attributed to the fact that DNA repair capacity varies in human populations, pointing the role of genetic susceptibility in human cancer. Numerous studies demonstrated that certain genetic and epigenetic alterations are fairly constant. Loss of heterozygosity (LOH) at chromosome 9 is an aberration found in urothelial cell carcinoma (UCC) of all stages and grades as well as in dysplastic urothelium, possibly representing an early event in urinary bladder carcinogenesis. On the contrary, gains of 3p can only be found in tumors demonstrating highly malignant behavior. Microsatellite instability (MSI) is another frequent finding in urinary bladder cancer. This has led many investigator groups to employ the analysis for MSI for early diagnosis of UCC with promising results. The silencing of certain genes such as p16(INK4A) and DAPK by aberrant methylation of their promoter region also represents an important mechanism in carcinogenesis. Similarly, alterations in certain tumor suppressor genes and proto-oncogenes result in uncontrolled cell proliferation, reduced apoptosis and have been associated with more aggressive UCC phenotypes. Undoubtedly, the application of these observations in clinical practice will make a breakthrough in the management of bladder cancer.
Insights
Genetic factors influence bladder cancer development, with specific DNA alterations like loss of heterozygosity (LOH) and microsatellite instability (MSI) aiding early diagnosis and predicting tumor behavior.
Area of Science:
- Oncology
- Genetics
- Molecular Biology
Background:
- Urinary bladder cancer (UCC) represents about 5% of new cancer diagnoses globally.
- Environmental factors like smoking and occupational exposures are key risks, but individual susceptibility varies.
- Genetic susceptibility, including variations in DNA repair capacity, plays a crucial role in unpredictable cancer development.
Purpose of the Study:
- To explore genetic and epigenetic alterations in urinary bladder cancer.
- To identify biomarkers for early diagnosis and predicting tumor aggressiveness.
- To understand the role of genetic susceptibility in bladder carcinogenesis.
Main Methods:
- Analysis of genetic aberrations such as loss of heterozygosity (LOH) at chromosome 9.
- Detection of microsatellite instability (MSI) for early diagnosis of urothelial cell carcinoma (UCC).
- Investigation of epigenetic modifications, including gene promoter methylation (e.g., p16(INK4A), DAPK).
- Examination of alterations in tumor suppressor genes and proto-oncogenes.
Main Results:
- Loss of heterozygosity (LOH) at chromosome 9 is an early event in UCC development.
- Microsatellite instability (MSI) analysis shows promise for early UCC diagnosis.
- Gene silencing via promoter methylation (e.g., p16(INK4A), DAPK) is a significant carcinogenic mechanism.
- Alterations in specific genes correlate with uncontrolled cell proliferation, reduced apoptosis, and aggressive UCC phenotypes.
Conclusions:
- Genetic and epigenetic alterations are critical in urinary bladder cancer development and progression.
- Biomarkers like LOH and MSI can aid in early UCC diagnosis and risk stratification.
- Understanding these molecular changes offers potential for breakthroughs in bladder cancer management.
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