A Reporter Mouse To Measure Drug Myelotoxicity In Time.

Myelotoxicity is the well known side effect of most anti-cancer treatments, thus the study of the myelosuppressive effect of a given treatment is tested routinely during the preclinical phase of investigation. Current ethodologies require the use of a very large number of animals to measure the effect of the investigated compound in time and the study is generally carried out by bone marrow dissection and subsequent analysis with a myeloid clonogenic assay. The goal of our study was to apply non invasive imaging technologies to generate a novel, simple and robust assay to test the state of proliferation of bone marrow reducing the number of animals to be sacrificed and increasing the power of the analysis thanks t the possibility to follow in time, in the same animal the effect of the treatment. To this aim, we have utilized a trangenic mouse, the repTOP ™ mitoIRE reporter mouse recently developed to image proliferative events in vivo (Goeman et al 2012, Oliva et al 2012). This transgenic mouse carries a luciferase reporter gene under the transcriptional control of a minimal human cyclin B2 promoter.Our in vitro and in vivo results show that the luciferase expression and photon emission in the different body regions of the repTOP ™ mitoIRE is strictly proportional to the proliferative state of the cells in the tissues examined. Our results demonstrate that the extent of bone marrow proliferation can be measured by in vivo imaging photon emission of femur and sternum in each mouse prior the treatment and then monitored during the longitudinal study. The repTOP ™ mitoIRE mouse model, was successfully applied to the study of the differential immunosuppressive potential of several well known anti-neoplastic treatments demonstrating the validity of the novel test over currently available methodologies: we measured the differential effects on immunosuppression and on regeneration of 5-fluorouracil, docetaxel, bortezomid, temozolomide and radiotherapy in dose-response experiments. The results led us to conclude that the imaging-based test here proposed is reproducible and provides a reliable measure of bone marrow cell proliferation in time and to propose it as a routine test in for the pre-clinical of novel anti-neoplastic compounds. Citation Format: Nicoletta Rizzi, Isabella Manni, Laura Mancini, Chiara Roncoroni, Electra Brunialti, Paolo Oliva, Maria Pia Gentileschi, Stefano Di Giovine, Enrico A. Pesenti, Giulia Piaggio, Adriana Maggi, Paolo Ciana. A reporter mouse to measure drug myelotoxicity in time. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4416. doi:10.1158/1538-7445.AM2013-4416