NOTCH pathway inactivation promotes bladder cancer progression

Area of Science:

• Oncology
• Molecular Biology
• Cell Biology

Background:

• NOTCH signaling is known to suppress tumor growth in stratified epithelia.
• Dysregulation of NOTCH signaling is implicated in various cancers.

Purpose of the Study:

• To investigate the role of NOTCH signaling in bladder cancer.
• To determine the functional consequences of NOTCH1 and NOTCH2 mutations in bladder tumorigenesis.

Main Methods:

• Analysis of missense mutations in NOTCH1 and NOTCH2 in human bladder cancers.
• Genetic ablation of the NOTCH pathway in murine bladder cancer models.
• In vitro studies using bladder cancer cells to assess the effect of NOTCH activity on epithelial-mesenchymal transition (EMT).
• Evaluation of human bladder cancer samples for HES1 levels and correlation with tumor features.

Main Results:

• Missense mutations in NOTCH1 and NOTCH2 in human bladder cancers lead to loss of function.
• NOTCH pathway ablation in mice accelerates bladder tumorigenesis and promotes squamous cell carcinomas with mesenchymal features.
• NOTCH signaling, via HES1, stabilizes the epithelial phenotype; loss of NOTCH activity promotes EMT.
• Human bladder tumors with low HES1 expression exhibit mesenchymal features and are associated with increased aggressiveness.

Conclusions:

• NOTCH signaling functions as a tumor suppressor in the bladder.
• Loss of NOTCH pathway activity promotes EMT, leading to more invasive and aggressive bladder cancer phenotypes.
• HES1 is a key effector in mediating the tumor-suppressive role of NOTCH in the bladder.