TGFβ pathway limits dedifferentiation following WNT and MAPK pathway activation to suppress intestinal tumourigenesis

Area of Science:

• Gastroenterology
• Cancer Biology
• Cellular Plasticity

Background:

• Differentiated intestinal cells can regain plasticity, acting as stem cells or tumor-initiating cells.
• Activating mutations in Kras or NF-κB pathway can induce dedifferentiation in Apc-deficient intestinal cells.
• The regulatory mechanisms governing this cellular plasticity remain largely unknown.

Purpose of the Study:

• To investigate the molecular processes regulating intestinal cell plasticity and dedifferentiation.
• To identify signaling pathways involved in Kras-driven dedifferentiation and subsequent tumor formation.
• To explore the therapeutic potential of targeting these pathways in colorectal cancer.

Main Methods:

• Gene expression profiling of dedifferentiating cells in vitro and tumors in vivo.
• Genetic inactivation of TGFβ type 1 receptor (Tgfbr1/Alk5).
• Pharmacological inhibition of MEK signaling.

Main Results:

• Dedifferentiation in vitro showed marked upregulation of TGFβ signaling, a pathway frequently mutated in colorectal cancer (CRC).
• Genetic inactivation of Tgfbr1/Alk5 enhanced Kras-driven dedifferentiation and accelerated tumorigenesis, linked to MAPK pathway activation.
• MEK inhibition potently inhibited tumorigenesis originating from differentiated compartments.

Conclusions:

• Tumors arising from differentiated intestinal compartments encounter suppressive signals like TGFβ.
• Blocking these suppressive signals, such as TGFβ, enhances tumor formation efficiency from differentiated cells.
• Targeting TGFβ and MAPK pathways presents a promising therapeutic strategy for colorectal cancer originating from differentiated compartments.