Geburtshilfe Frauenheilkd 2014; 74 - FV_03_02
DOI: 10.1055/s-0034-1388555

Knockdown of TRAIL-R2 in breast cancer cells impairs bone metastases formation in a preclinical mouse model

T Heilmann 1, 2, H Fritsche 2, R Towers 3, G Campbell 3, M Rauner 4, C Hauser 2, S Tiwari 3, W Jonat 1, C Schem 1, H Kalthoff 2, A Trauzold 2
  • 1Department of Gynecology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany
  • 2Division of Molecular Oncology, Institute for Experimental Cancer Research, University of Kiel, Kiel, Germany
  • 3Section Biomedical Imaging, Department of Diagnostic Radiology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany
  • 4Division of Endocrinology, Diabetes, and Bone Diseases, Department of Medicine III, Dresden University Medical Center, Dresden, Germany

Introduction: Plasma-membrane localized death receptors TRAIL-R1/R2 induce apoptosis and pro-inflammatory responses when crosslinked by their ligand TRAIL. In its nuclear localization TRAIL-R2 promotes cell proliferation by regulating the maturation of miRNA let-7. Interestingly, overexpression of TRAIL-R2 has been correlated with worse prognosis for patients with breast cancer, which is known to frequently metastasize to the bone. In the present study, using a preclinical mouse model, we analyzed the impact of TRAIL-R2 on the ability of breast cancer cells to form bone metastases.

Methods: Bone seeking MDA-MB-231-cells were transfected with TRAIL-R2-shRNA and intracardially injected in SCID-beige-mice. In vivo imaging of the bone metastases was performed by bioluminescence, MRI and µCT-analysis. Characterization of the cell-phenotype was accomplished in vitro by using Western-Blotting, ELISA and migration assays.

Results: The knockdown of TRAIL-R2 strongly diminished the frequency of bone metastases in breast cancer cells. No difference was detected in the osteolytic bone loss by µ-CT. The cells exhibit a mixed EMT-phenotype and an inhibited migration towards SDF1.

Fig. 1 Reduced bone metastases burden in cells with reduced levels of TRAIL-R2.
MDA-231 cells expressing control or TRAIL-R2-targeted short hairpin constructs were intracardially injected into SCID-Beige mice and monitored weekly by bioluminescence imaging using the NightOwl planar imaging system (Berthold Technologies, Bad Wildbad. Germany). Results are shown for the time point 5 weeks after inoculation at which the number of mice with bioluminescent tumor, the average number of tumors per mouse and average tumor area was determined.

Conclusion: TRAIL-R2 plays an important role in the capability of breast cancer cells to form bone metastases. It therefore might display a critical target in the multimodal therapy of breast cancer in advanced tumor stages.