SKP2 cooperates with N-Ras or AKT to induce liver tumor development in mice

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• S-Phase Kinase-Associated Protein 2 (SKP2) is frequently overexpressed in human hepatocellular carcinoma (HCC).
• The precise role of SKP2 in the development of liver cancer (hepatocarcinogenesis) is not fully understood.
• Understanding SKP2's function is crucial for developing targeted therapies for HCC.

Purpose of the Study:

• To investigate the specific functions of SKP2 in the development of hepatocellular carcinoma (HCC).
• To determine how SKP2 interacts with other oncogenes (N-Ras, AKT1, β-catenin) in promoting liver cancer.
• To elucidate the molecular mechanisms underlying SKP2-driven hepatocarcinogenesis.

Main Methods:

• Stable overexpression of the SKP2 gene in mouse liver using hydrodynamic gene delivery.
• Co-expression of SKP2 with activated forms of N-Ras (N-RasV12), AKT1 (myr-AKT1), or β-catenin (ΔN90-β-catenin).
• Analysis of molecular pathways (AKT/mTOR, Ras/MAPK) and tumor suppressor protein levels in liver lesions.

Main Results:

• Overexpression of SKP2 alone, N-RasV12, or ΔN90-β-catenin did not induce liver tumors.
• Co-expression of SKP2 with N-RasV12 or myr-AKT1 led to rapid development of multiple hepatocellular tumors.
• AKT/mTOR and Ras/MAPK pathways were significantly activated in tumors from SKP2-co-expressing mice.
• Key tumor suppressor proteins (p27, p57, Dusp1, Rassf1A) were not decreased, contrary to findings in other cancers.

Conclusions:

• SKP2 cooperates with N-Ras and AKT proto-oncogenes to drive hepatocarcinogenesis in vivo.
• SKP2's oncogenic role in HCC involves the activation of AKT/mTOR and Ras/MAPK signaling pathways.
• Nuclear SKP2 translocation in human HCC correlates with these pathway activations, but not β-catenin mutations.