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Alterations of Fas (APO-1/CD95) gene in transitional cell carcinomas of urinary bladder
1Department of Pathology, College of Medicine, The Catholic University of Korea, Seoul.
Abstract:
Fas (Apo-1/CD95) is a cell-surface receptor involved in cell death signaling. The key role of the Fas system in negative growth regulation has been studied mostly within the immune system, and somatic mutations of Fas in cancer patients have been described solely in lymphoid-lineage malignancies. We analyzed somatic mutations and loss of heterozygosity of Fas gene in 43 transitional cell carcinomas of urinary bladder. Overall, 12 tumors (28%) were found to have Fas mutations, including 11 missense mutations and 1 frameshift mutation. Ten of the 12 mutations were located in the death domain known to be involved in the transduction of an apoptotic signal, and 8 of these 10 mutations showed an identical G to A transition at bp 993, indicating a potential hotspot in bladder cancers. Three of eight (38%) informative tumors carrying Fas mutations showed LOH at polymorphic sites in the promoter region. This is the first report on the Fas gene mutations in nonlymphoid malignancies, and our data suggest that alterations of the Fas gene might lead to the loss of its apoptotic function and contribute to the pathogenesis of some bladder cancers.
Insights
Fas gene mutations are found in bladder cancers, potentially disrupting cell death signaling and contributing to tumor development. This study highlights Fas alterations in non-lymphoid malignancies for the first time.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- The Fas receptor (Apo-1/CD95) is crucial for cell death signaling, primarily studied in the immune system.
- Somatic Fas mutations were previously reported only in lymphoid cancers, suggesting limited roles in other malignancies.
Purpose of the Study:
- To investigate somatic mutations and loss of heterozygosity (LOH) of the Fas gene in transitional cell carcinomas of the urinary bladder.
- To determine if Fas gene alterations contribute to bladder cancer pathogenesis.
Main Methods:
- Analysis of somatic mutations and LOH in the Fas gene from 43 transitional cell carcinoma samples.
- Identification of mutation types, locations (including the death domain), and potential mutation hotspots.
- Assessment of LOH at polymorphic sites within the Fas promoter region.
Main Results:
- Fas mutations were identified in 28% (12/43) of bladder tumors, including missense and frameshift types.
- Ten mutations were in the death domain, with a specific G to A transition at bp 993 observed in 8 cases, indicating a hotspot.
- Loss of heterozygosity in the Fas promoter region was found in 38% of informative tumors with Fas mutations.
Conclusions:
- This is the first report of Fas gene mutations in non-lymphoid malignancies, specifically bladder cancer.
- Alterations in the Fas gene may impair its apoptotic function, contributing to the development of some bladder cancers.
- The identified mutation hotspot suggests a specific mechanism of Fas dysregulation in bladder tumorigenesis.