Elevating SOX2 Downregulates MYC through a SOX2:MYC Signaling Axis and Induces a Slowly Cycling Proliferative State...

Area of Science:

• Oncology
• Molecular Biology
• Cell Biology

Background:

• Slowly cycling tumor cells evade treatment, posing a clinical challenge.
• High SOX2 levels are known to restrict cell proliferation and induce slow cycling.
• The precise mechanisms by which SOX2 inhibits proliferation remain unidentified.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying SOX2-mediated inhibition of tumor cell proliferation.
• To identify common pathways affected by elevated SOX2 across different cancer types.

Main Methods:

• RNA sequencing (RNA-seq) was performed on two diverse tumor cell types with elevated SOX2.
• SOX2 expression was manipulated in five cell lines from three human cancer types.
• The effects of a dominant-negative MYC variant (omomyc) were assessed.
• MYC activity was rescued in cells with elevated SOX2 to observe effects on cell death.

Main Results:

• Elevated SOX2 downregulated MYC target genes in both tested cell types.
• Increased SOX2 consistently decreased MYC expression across multiple cancer cell lines.
• Omomyc expression mimicked SOX2's effects on proliferation, cell cycle, gene expression, and biosynthesis.
• Rescuing MYC activity in SOX2-elevated cells led to cell death.

Conclusions:

• A novel SOX2:MYC signaling axis was uncovered.
• Downregulation of MYC is essential for tumor cell survival in the SOX2-induced slowly cycling state.
• These findings provide critical insights into how SOX2 promotes a non-proliferative state in cancer cells.