BRD4 binding sites in transformed fibroblasts

Analysis of BRD4 ChIP-seq data of two types of human transformed fibroblasts (WT and HGPS) to identify specific and common binding sites for BRD4. Transformed cell lines were obtained by retroviral introduction of TERT (T), V12-HRAS (R) and SV40 large and small T antigens (S) of primary skin fibroblasts for HGPS patients (TRS-HGPS) and age-matched control wild-type individuals (TRS-WT)Abstract: Advanced age and DNA damage accumulation are strong risk factors for cancer. The premature-aging disorder Hutchinson Gilford Progeria Syndrome (HGPS) provides a unique opportunity to study the interplay between DNA damage and aging-associated tumor mechanisms, since 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 neo-plastic transformation. This resistance is mediated by the bromodomain protein BRD4, which exhibits altered genome-wide binding patterns in transformation-resistant cells leading to inhibition of oncogenic de-differentiation. BRD4 also in-hibits, albeit to a lower extent, the tumorigenic potential of transformed cells from healthy individuals and BRD4-mediated tumor protection is clinically relevant, since 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 functions for BRD4 in tumorigenesis.