Mutational Mechanisms That Activate Wnt Signaling and Predict Outcomes in Colorectal Cancer Patients

Area of Science:

• Oncology
• Genetics
• Molecular Biology

Background:

• Adenomatous polyposis coli (APC) mutations are common in colorectal tumors, activating WNT signaling.
• The role of APC mutations versus CTNNB1 (β-catenin) gain-of-function mutations in colorectal cancer development is not fully understood.

Purpose of the Study:

• To investigate if APC loss-of-function mutations phenocopy CTNNB1 gain-of-function mutations in activating WNT signaling.
• To determine if distinct mutational mechanisms lead to different gene expression profiles and impact colorectal cancer outcomes.

Main Methods:

• Gene expression profiling of Apc-mutant and Ctnnb1-mutant mouse colon adenomas.
• Analysis of The Cancer Genome Atlas (TCGA) data for human colorectal cancer outcomes.

Main Results:

• Both APC and CTNNB1 mutations activate canonical WNT signaling but result in distinct transcriptional patterns.
• APC-mutant adenomas show unique alterations in proliferation, cytoskeletal organization, and apoptosis pathways.
• Increased Serpine2 expression in APC-mutant adenomas correlates with advanced human colorectal tumors.

Conclusions:

• APC-mutant colorectal tumors are transcriptionally distinct from those with other WNT activation mechanisms.
• These transcriptional differences have implications for stratifying patients and improving prognosis in advanced colorectal cancer.