Background: Angiogenesis is critical for the growth and metastasis of solid tumors and is, therefore, an important therapeutic target. Despite the great research advances in tumor therapies targeting vascular endothelial growth factor (VEGF), drug resistance frequently occurs, and further strategies targeting the tumor vasculature are of primary concern. 
Purpose: The present study aimed to determine whether a combination of small interfering RNAs (siRNAs) targeting VEGF-A and angiopoietin-2 (Ang-2) inhibited the biologic mechanisms of endometrial cancer more effectively compared to either one alone, in vitro and in vivo.
Methods: VEGF-A and Ang-2 were silenced by siRNA in Ishikawa endometrial cancer cells. Cell growth, apoptosis, metastasis, and tumor angiogenesis were measured in vitro and in vivo. 
Results: There was no difference observed in cell apoptosis rate; however, combined silencing of VEGF-A and Ang-2 resulted in a stronger inhibition of cell proliferation and invasion (P <0.05). Similarly, a greater reduction of tumor size and angiogenesis was seen with the concurrent administration of siRNAs targeting VEGF-A and Ang-2 in nude mice (P <0.05). 
Conclusion: Our data indicated that simultaneous blockade of VEGF-A and Ang-2 may serve as a novel and effective therapeutic strategy in endometrial cancer.
Keywords: drug resistance, siRNA, Ang-2, angiogenesis