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Identification of c-MYC as a target of the APC pathway
1Howard Hughes Medical Institute and Johns Hopkins Oncology Center, 424 North Bond Street, Baltimore, MD 21231, USA.
Abstract:
The adenomatous polyposis coli gene (APC) is a tumor suppressor gene that is inactivated in most colorectal cancers. Mutations of APC cause aberrant accumulation of beta-catenin, which then binds T cell factor-4 (Tcf-4), causing increased transcriptional activation of unknown genes. Here, the c-MYC oncogene is identified as a target gene in this signaling pathway. Expression of c-MYC was shown to be repressed by wild-type APC and activated by beta-catenin, and these effects were mediated through Tcf-4 binding sites in the c-MYC promoter. These results provide a molecular framework for understanding the previously enigmatic overexpression of c-MYC in colorectal cancers.
Insights
The adenomatous polyposis coli (APC) gene, crucial for preventing tumors, is often mutated in colorectal cancer. This study reveals that APC inactivation leads to c-MYC oncogene activation, explaining its common overexpression in these cancers.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- The adenomatous polyposis coli (APC) gene is a critical tumor suppressor frequently inactivated in colorectal cancers.
- APC mutations lead to beta-catenin accumulation, which interacts with T cell factor-4 (Tcf-4) to drive aberrant gene transcription.
Discussion:
- This research identifies the c-MYC oncogene as a direct target within the APC/beta-catenin/Tcf-4 signaling pathway.
- Wild-type APC represses c-MYC expression, while accumulated beta-catenin activates it via Tcf-4 binding sites on the c-MYC promoter.
Key Insights:
- Establishes a direct molecular link between APC tumor suppressor inactivation and c-MYC oncogene activation.
- Provides a mechanism for the well-documented overexpression of c-MYC in colorectal tumorigenesis.
- Highlights the role of the APC/beta-catenin/Tcf-4 pathway in regulating c-MYC transcription.
Outlook:
- Further investigation into targeting the APC/beta-catenin/Tcf-4/c-MYC axis could yield novel therapeutic strategies for colorectal cancer.
- Understanding this pathway's regulation may offer insights into other cancers where APC or c-MYC are implicated.
- This framework can guide research into the precise downstream targets and functions of c-MYC in colorectal cancer development.