Sequential cancer mutations in cultured human intestinal stem cells.

Area of Science:

• Gastroenterology
• Oncology
• Stem Cell Biology

Background:

• Intestinal stem cells are the origin of colorectal cancer.
• Human intestinal stem cells can be cultured as stable epithelial organoids.
• Key genes like APC, P53, KRAS, and SMAD4 are frequently mutated in colorectal cancer.

Purpose of the Study:

• To genetically modify human intestinal stem cells using CRISPR/Cas9.
• To investigate the role of common colorectal cancer gene mutations in organoid development and tumor formation.
• To understand the early events in colorectal cancer progression.

Main Methods:

• Utilized CRISPR/Cas9 for targeted gene editing in cultured human intestinal stem cells.
• Developed genetically modified intestinal organoids.
• Selected mutant organoids by manipulating culture medium growth factors.
• Xenotransplanted mutant organoids into mice for tumor formation studies.

Main Results:

• Generated organoids with mutations in APC, P53, KRAS, and SMAD4.
• Quadruple mutant organoids grew independently of stem cell niche factors.
• Mutant organoids tolerated P53 stabilization.
• Xenotransplanted quadruple mutants formed invasive carcinomas in mice.
• Loss of APC and P53 induced aneuploidy, a hallmark of tumor progression.

Conclusions:

• Genetically engineered human intestinal stem cell organoids serve as a model for colorectal cancer.
• Specific gene mutations drive tumor initiation and progression.
• Combined APC and P53 loss is sufficient to initiate aneuploidy in intestinal neoplasia.