Hedgehog pathway activity is required for the lethality and intestinal phenotypes of mice with hyperactive Wnt...

Area of Science:

• Molecular Biology
• Oncology
• Developmental Biology

Background:

• WNT signaling, particularly via beta-catenin/TCF, is crucial in initiating intestinal tumorigenesis, often linked to APC loss.
• HEDGEHOG-GLI (HH-GLI) signaling also plays a significant role in human colon cancers.
• The interaction between WNT and HH pathways in intestinal development, homeostasis, and cancer remains poorly understood.

Purpose of the Study:

• To elucidate the interplay between WNT and HH signaling pathways during intestinal development and cancer.
• To investigate the role of HH-GLI signaling in WNT-driven intestinal tumorigenesis.
• To validate a mouse model for preclinical testing of HH pathway antagonists.

Main Methods:

• Utilized conditional knockout (KO) mouse models to study the effects of WNT and HH pathway modulation.
• Analyzed marker expression to understand paracrine signaling in normal adult mouse intestines.
• Inhibited the Hh pathway mediator Smoothened (Smo) in Apc-deficient mice.

Main Results:

• Loss of APC leads to WNT pathway activation, inducing intestinal adenomas.
• Inhibition of Smoothened (Smo) rescues lethality and intestinal phenotypes in Apc-deficient mice.
• HH-GLI signaling is essential in tumors driven by hyperactive WNT signaling, acting in parallel or downstream.

Conclusions:

• The HH-GLI pathway is critical for tumors initiated by WNT hyperactivation.
• HH-GLI signaling functions in parallel or downstream of WNT signaling in intestinal tumorigenesis.
• The studied mouse model is suitable for preclinical evaluation of HH pathway inhibitors.