Rapamycin rescues APC-mutated colon organoid differentiation

Area of Science:

• Genetics and Molecular Biology
• Cancer Research
• Stem Cell Biology

Background:

• Familial adenomatous polyposis (FAP) is an inherited disorder caused by APC gene mutations, leading to colorectal adenomas and cancer.
• Understanding the molecular mechanisms driving FAP is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the diverse carcinogenic mechanisms in FAP driven by different APC mutations using a human embryonic stem cell (hESC)-derived colon organoid model.
• To explore the potential of rapamycin as a personalized therapeutic strategy for FAP.

Main Methods:

• Utilized hESC-derived colon organoids from FAP patients with distinct APC mutations (FAP1 and FAP2).
• Analyzed molecular pathways, including mTOR signaling, PTEN, S6K1, eIF4E, and c-Myc.
• Assessed the effect of rapamycin treatment on organoid differentiation and validated findings in patient-derived tissues.

Main Results:

• FAP1 organoids with a truncated APC protein showed mTOR pathway hyperactivation, PTEN inactivation, and apoptosis resistance.
• Rapamycin treatment rescued differentiation in FAP1 organoids but not FAP2 organoids, which lacked mTOR pathway activation.
• Patient data confirmed mTOR pathway activation in FAP1 tumors, correlating with organoid findings.

Conclusions:

• Distinct APC mutation types in FAP activate diverse carcinogenic mechanisms, including mTOR-mediated pathways.
• Rapamycin demonstrates potential as a personalized therapy for FAP patients with specific mTOR-activated APC mutations.
• The hESC-derived colon organoid model is a valuable tool for FAP research and therapeutic development.