TU4: INVOLVEMENT OF C-JUN IN HUMAN LIPOSARCOMA PROGRESSION IN A NEW ORTHOTOPIC DISEASE MODEL

Abstract

The c-jun oncogene is upregulated in a variety of cancers. c-jun has also been implicated in liposar-coma (LS) progression. A DNAzyme degrading c-jun mRNA was tested for effects on LS progression in vitro. A novel orthotopic model for LS was established in mice enabling in vivo evaluation of c-jun downregulation.

The human LS cell line (SW872) was transfected with Dz13, (DNAzyme degrading c-jun mRNA). A scrambled DNAzyme group and a non-transfected group were used as controls. Apoptosis of SW872 was evaluated with TUNEL, caspase inhibitor and Fas/FasL assays. The orthotopic mouse model involved injecting the SW872 cell line intramuscularly within the hind limb of nude mice, and calculating tumour volume on a weekly basis for 13 weeks. The effects of Dz13 transfection were then tested in this clinically relevant model.

In LS cells, caspase-10, but not Fas/FasL, was found to be responsible for apoptosis in Dz13-mediated c-jun knockdown. In the mouse model, tumour take in vivo was 100%, with growths resembling high grade aggressive LS, palpable at 8 weeks. SW872 cells grew within the muscle resembling the undifferentiated high grade malignant component of LS growth. The c-jun DNA-zyme inhibited the growth of LS in this model with at least 60% reduction of tumour weight or 70% reduction of tumour volume in the Dz13 cohort of animals at the end of the experiment. Tumour volumes were different between Dz13 and the control groups of animals by eleven days following injection (P< 0.05).

DNAzyme-mediated c-jun knockdown induces apoptosis in LS cells via caspase-10. This corresponds with reduced tumour growth in vivo. Clinically, downregulation of c-jun may proffer an improved treatment outcome for LS. The new model for LS described here will enable better testing of agents with therapeutic potential against LS.