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The random development of LOH on chromosome 9q in superficial bladder cancers
Angela A G van Tilborg1, Annie de Vries, Maarten de Bont
1Department of Pathology, Josephine Nefkens Institute, Erasmus University Rotterdam, PO Box 1738, The Netherlands.
Abstract:
Allelic loss on chromosome 9q is a very frequent event in bladder carcinogenesis. In recent years, efforts have been directed towards identifying the postulated tumour suppressor genes on this chromosome arm by deletion mapping and mutation analysis. However, no convincing candidate genes have been identified. This paper describes the development of chromosome 9q alterations in multiple recurrent superficial bladder cancers of ten patients and shows that loss of heterozygosity (LOH) on this chromosome is almost never the characteristic first step. The regions of loss are multiple and variable in different tumours from the same patient and expand in subsequent tumours. Moreover, the regions of loss vary from patient to patient. It is concluded that even if 9q harbours a bladder cancer gatekeeper gene, it is unlikely that the gene will be identified through LOH analysis alone.
Insights
Loss of heterozygosity (LOH) on chromosome 9q is common in bladder cancer but not an early event. Identifying bladder cancer genes via LOH alone is challenging due to variable and expanding chromosomal alterations.
Area of Science:
- Oncology
- Genetics
- Cancer Research
Background:
- Allelic loss on chromosome 9q is frequent in bladder cancer.
- Previous attempts to identify tumor suppressor genes on 9q using deletion mapping and mutation analysis have been unsuccessful.
Purpose of the Study:
- To investigate the development of chromosome 9q alterations in multiple, recurrent superficial bladder cancers.
- To determine if loss of heterozygosity (LOH) is an early event in bladder carcinogenesis.
Main Methods:
- Analysis of chromosome 9q alterations in tumor samples from ten bladder cancer patients.
- Deletion mapping and mutation analysis to track chromosomal changes.
Main Results:
- Loss of heterozygosity (LOH) on chromosome 9q is not typically the initial event in bladder cancer development.
- Regions of chromosomal loss are multiple, variable between tumors from the same patient, and expand in subsequent tumors.
- Observed chromosomal loss patterns differ significantly among patients.
Conclusions:
- The identified patterns of chromosomal alterations suggest that LOH analysis alone may be insufficient to identify potential bladder cancer gatekeeper genes on chromosome 9q.
- Further research is needed to explore alternative methods for identifying tumor suppressor genes in bladder carcinogenesis.