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p16 involvement in primary bladder tumors: analysis of deletions and mutations
E Baud1, P Catilina, Y J Bignon
1Laboratoire d'Oncologie Moleculaire, INSERM CRI 9502 EA2145, Centre Jean Perrin, 63011 Clermont-Ferrand, France.
Abstract:
Different studies have proposed that genetic alterations leading to inactivation of a tumor suppressor gene on chromosome 9 is an important early event in bladder tumorigenesis. Recent reports have described the p16 gene as the main target. In order to better define its role, we studied 9p21 deletions by microsatellite analysis and its coding sequence. Forty-eight percent of the 44 samples we studied showed LOH surrounding p16. Three of these 44 samples displayed point mutations in p16 and three others were suspected of homozygous deletion. These results suggest that simultaneous loss of both p16 alleles, by point mutation or homozygous deletion, seems to be infrequent in bladder tumors.
Insights
Genetic alterations in bladder cancer are common. This study investigated the p16 tumor suppressor gene, finding simultaneous loss of both p16 alleles to be infrequent in bladder tumors.
Area of Science:
- Oncology
- Genetics
- Molecular Biology
Background:
- Tumor suppressor genes on chromosome 9 are implicated in bladder cancer development.
- The p16 gene has been identified as a potential key target in bladder tumorigenesis.
Purpose of the Study:
- To investigate the role of 9p21 deletions and p16 gene alterations in bladder cancer.
- To determine the frequency of p16 gene inactivation in bladder tumors.
Main Methods:
- Microsatellite analysis was used to study 9p21 deletions.
- The coding sequence of the p16 gene was analyzed for mutations.
Main Results:
- Loss of heterozygosity (LOH) surrounding p16 was observed in 48% of the 44 samples analyzed.
- Point mutations in p16 were found in three samples.
- Homozygous deletion of p16 was suspected in three other samples.
Conclusions:
- Simultaneous inactivation of both p16 alleles through point mutation or homozygous deletion appears to be infrequent in bladder tumors.
- While p16 alterations are present, their combined loss may not be a predominant early event in all bladder tumorigenesis.