title: Noninvasive assessment of E2F-1-mediated transcriptional regulation in vivo.
abstract: Targeted therapies directed against individual cancer-specific molecular alterations offer the development of disease-specific and individualized treatment strategies. Activation of the transcription factor E2F-1 via alteration of the p16-cyclinD-Rb pathway is one of the key molecular events in the development of gliomas. E2F-1 binds to and activates the E2F-1 promoter in an autoregulatory manner. The human E2F-1 promoter has been shown to be selectively activated in tumor cells with a defect in the pRb pathway. Paradoxically, E2F-1 also carries tumor suppressor function. Our investigations focused on analyzing the dynamics of the activity of the E2F-1 responsive element under basal conditions and certain stimuli such as chemotherapy using molecular imaging technology. We constructed a retrovirus bearing the Cis-E2F-TA-LITG reporter system to noninvasively assess E2F-1-dependent transcriptional regulation in culture and in vivo. We show that our reporter system is sensitive to monitor various changes in cellular E2F-1 levels and its transcriptional control of our reporter system to follow the state of the Rb/E2F pathway and the DNA damage-induced up-regulation of E2F-1 activity in vivo. Exposure to 1,3-bis(2-chloroethyl)-1-nitrosourea leads to increased E2F-1 expression levels in a dose- and time-dependent manner, which can be quantified by imaging in vivo, leading to an alteration of cell cycle progression and caspase 3/7 activity. In summary, noninvasive imaging of E2F-1 as a common downstream regulator of cell cycle progression using the Cis-E2F-TA-LUC-IRES-TKGFP reporter system is highly attractive for evaluating the kinetics of cell cycle regulation and the effects of novel cell cycle targeting anticancer agents in vivo.
authors.affiliation: Laboratory for Gene Therapy and Molecular Imaging, Max-Planck Institute for Neurological Research with Klaus-Joachim-Zülch-Laboratories of the Max Planck Society, Faculty of Medicine, University of Cologne, Cologne, Germany.
authors.forename: Parisa
authors.initials: P
authors.lastname: Monfared
authors.forename: Alexandra
authors.initials: A
authors.lastname: Winkeler
authors.forename: Markus
authors.initials: M
authors.lastname: Klein
authors.forename: Hongfeng
authors.initials: H
authors.lastname: Li
authors.forename: Anke
authors.initials: A
authors.lastname: Klose
authors.forename: Marianna
authors.initials: M
authors.lastname: Hoesel
authors.forename: Yannic
authors.initials: Y
authors.lastname: Waerzeggers
authors.forename: Sigrun
authors.initials: S
authors.lastname: Korsching
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Jacobs
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000235:genetics / Q000378:metabolism*; D002330:Carmustine / Q000494:pharmacology; D045744:Cell Line, Tumor; D004249:DNA Damage; D018450:Disease Progression; D050687:E2F1 Transcription Factor / Q000235:genetics* / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D005910:Glioma / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D008856:Microscopy, Fluorescence / Q000295:instrumentation / Q000379:methods*; D012190:Retroviridae / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D050687:E2F1 Transcription Factor; D002330:Carmustine