title: PAC1 is a direct transcription target of E2F-1 in apoptotic signaling.
abstract: E2F-1 controls multiple cellular activities through transcriptional regulation of its target genes. As a mediator of cell death, E2F-1 can eliminate latent neoplastic cells through apoptosis. However, the mechanism by which E2F-1 mediates cancer cell killing is largely unknown. In this paper, we report that phosphatase of activated cells 1 (PAC1) phosphatase is a direct transcription target of E2F-1 in signaling apoptosis. We show that ectopic E2F-1 increases expression of PAC1 at both transcriptional and translational levels in breast cancer cells. E2F-1 physically interacts with the promoter of PAC1, binds to its consensus sequence in the promoter and transactivates the PAC1 promoter. E2F-1 suppresses extracellular signal-regulated kinase (ERK) phosphorylation through PAC1 and causes cancer cell death by apoptosis following treatment with a chemotherapeutic agent N-4-hydroxyphenylretinamide (4-HPR). Furthermore, ectopic PAC1 inhibits ERK phosphorylation and mediates cell killing. Moreover, endogenous E2F-1 upregulates PAC1 and suppresses ERK activity, leading to cell death in response to 4-HPR. These results reveal a crucial role of PAC1 in E2F-1-directed apoptosis. Our study demonstrates that E2F-1 mediates apoptosis through transcriptional regulation of PAC1 and subsequent suppression of the ERK signaling. Our findings establish a functional link between E2F-1 and mitogen-activated protein kinases. The E2F-1-PAC1 cascade in cancer cell killing may provide a molecular basis for cancer therapeutic intervention.
authors.affiliation: Department of Radiation Oncology, Center for Radiological Research, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
authors.forename: J
authors.initials: J
authors.lastname: Wu
authors.forename: Y J
authors.initials: YJ
authors.lastname: Jin
authors.forename: G M
authors.initials: GM
authors.lastname: Calaf
authors.forename: W-L
authors.initials: WL
authors.lastname: Huang
authors.forename: Y
authors.initials: Y
authors.lastname: Yin
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D001483:Base Sequence; D001943:Breast Neoplasms / Q000378:metabolism; D045744:Cell Line, Tumor; D054641:Dual Specificity Phosphatase 2 / Q000502:physiology*; D050687:E2F1 Transcription Factor / Q000502:physiology*; D017313:Fenretinide / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: D000970:Antineoplastic Agents; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D017313:Fenretinide; D019950:Mitogen-Activated Protein Kinase 1; D054641:Dual Specificity Phosphatase 2