Firefox, a protein encoded by circular PVT1, is essential for MYC-driven oncogenesis.

Firefox, a protein encoded by circular PVT1, is essential for MYC-driven oncogenesis, as its depletion reduces MYC protein levels and tumor growth in models.

• Why it matters: MYC-driven cancers are highly aggressive and often fatal, with MYC overexpression alone insufficient for tumorigenesis, highlighting the need to understand co-factors that sustain MYC activity.
• What they did: The study identified that circular PVT1 produces Firefox (FFX), a protein that stimulates AKT-mTORC1 signaling and enhances MYC activity, with genomic rearrangements favoring 5'- PVT1 and FFX production; FFX depletion markedly reduces MYC protein and tumor growth in vivo.
• The result: These findings establish FFX as a critical effector in MYC-driven cancers and suggest it as a promising therapeutic target to disrupt MYC oncogenic signaling.