Klinische Neurophysiologie 2011; 42 - A16
DOI: 10.1055/s-0031-1272660

Targeting the p53 tumor suppressor activity in glioblastomas using small molecule MDM2-inhibitor

P. Monfared 1, T. Viel 1, G. Schneider 1, Y. Waerzeggers 1, S. Rapic 1, B. Neumaier 1, H. Backes 1, A. Winkeler 1, A.H. Jacobs 1
  • 1Köln, Münster

Introduction: Targeted therapies that inhibit the MDM2-p53 interaction and the downstream RB-E2F signalling pathway have shown promising antitumor activity, but their efficacy in gliomas has not been investigated. Small-molecule MDM2 antagonists have been developed to specifically inhibit the MDM2-p53 interaction, thereby activating p53 signalling serving anti-tumor activity.

Aims: To investigate the therapeutic potential of disrupting the MDM2-p53 interaction in human gliomas cells with various p53 status. We particularly followed whether MDM2-inhibition would sensitize gliomas to additional chemotherapy.

Methods: We investigated the activity of MDM2-inhibitor alone and in combination with chemotherapy on cell cycle regulating proteins by Western blot and in vivo by employing molecular imaging sensing vectors.

Results: MDM2-inhibitor alone and in combination with BCNU results in a dose- and time-dependent reduction in cell viability and proliferation. Western blot studies showed that MDM2-inhibition modifies expression of several genes and results in cell cycle arrest and induction of apoptosis. Moreover, we found consistent and robust accumulation of p53 protein and downregulation of E2F-1 protein triggered by MDM2-inhibition alone and in combination with BCNU in all glioma cells as well as primary glioma samples. The MDM2-inhibitor and BCNU mediated dynamic alteration of p53 and E2F1 activities could be quantified in vivo by bioluminescence imaging and correlated to our results in culture.

Conclusions: Our study demonstrates that the small MDM2 inhibitor in combination with chemotherapy provides a powerful trigger towards the induction of apoptosis in glioma cells by p53-dependent and p-53-independent mechanisms. Notably, employing sensing vectors enables us to specifically study the dynamics of Nutlin-3 induced alterations of cell cycle regulating protein expression in vivo. Our findings suggest that MDM2 inhibitor may serve a promising approach for molecular targeted glioma therapy.

Acknowledgement: This work is supported in part by the EC-FP6 European DiMI, (LSHC-CT-2004–503569), LSHB-CT-2005–512146 and Clinigene (LSHB-CT-06–018933).