Transformation Resistance in a Premature Aging Disorder Identifies a Tumor-Protective Function of BRD4

• HGPS patient cells are resistant to oncogenic transformation
• BRD4 is identified through an RNAi screen as a mediator of transformation resistance
• BRD4 inhibits oncogenic dedifferentiation
• Clinical outcomes suggest tissue-specific functions for BRD4

SummaryAdvanced age and DNA damage accumulation are prominent risk factors for cancer. The premature aging disorder Hutchinson-Gilford progeria syndrome (HGPS) provides a unique opportunity for studying the interplay between DNA damage and aging-associated tumor mechanisms, given that HGPS patients do not develop tumors despite elevated levels of DNA damage. Here, we have used HGPS patient cells to identify a protective mechanism to oncogenesis. We find that HGPS cells are resistant to neoplastic transformation. Resistance is mediated by the bromodomain protein BRD4, which exhibits altered genome-wide binding patterns in transformation-resistant cells, leading to inhibition of oncogenic dedifferentiation. BRD4 also inhibits, albeit to a lower extent, the tumorigenic potential of transformed cells from healthy individuals. BRD4-mediated tumor protection is clinically relevant given that a BRD4 gene signature predicts positive clinical outcome in breast and lung cancer. Our results demonstrate a protective function for BRD4 and suggest tissue-specific roles for BRD4 in tumorigenesis.

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