New targets and therapeutic approaches for vascular targeted strategies in oncology are continuously explored.
Endoglin, a co-receptor of TGF-β, is a known target, however, its silencing with vector-based RNA interference technology
has not been evaluated yet. Therefore, in our study, we assembled plasmid DNA coding for shRNA against endoglin,
and used gene electrotransfer as a delivery method to determine its antitumor and vascular targeted effects. In vitro and in
vivo data provide evidence of vascular targeted effects of endoglin silencing. The vascular targeted action of endoglin silencing
could be described as a result of two separated effect; antiangiogenic and vascular disrupting effect. This was first
supported by in vitro data; predominantly by reduction of proliferation and tube formation of endothelial cells. In the
TS/A murine mammary carcinoma model, in which the tumor cells do not express endoglin, reduced tumor growth and
number of vessels were observed. Quick destruction of existing activated blood vessels at the site of tumor cells’ injection
and sustained growth of tumors afterwards was observed in tumors that were growing in dorsal window chamber by intravital
microscopy. This observation supports both vascular disrupting and antiangiogenic action. In conclusion, the results
of our study provide evidence of endoglin as a valid target for cancer therapy and support further development of
plasmid shRNA delivery, which have prolonged antitumor effect, especially in combined schedules.