Vascular endothelial growth factor antagonist peptides inhibit tumor growth and metastasis in breast cancer through repression of c-src and STAT3 genes.

Background: Breast cancer is one of the most decisive causes of cancer death in women worldwide. Cancer progression and tumor metastasis depend on angiogenesis. Vascular endothelial growth factor (VEGF) and its receptors (VEGFR1 and VEGFR2) are critically required for tumor angiogenesis. Src is involved in many of the VEGF-mediated pathways. The VEGFRs activate Src via different mechanisms. Given that Src activates STAT3 (signal transducers and activators of transcription) repressing apoptosis and promoting the cell cycle, it may be an important object for cancer treatment.

Methods And Results: A series of VEGF antagonistic peptides, referred to as VGB 1,3 and 4, were designed to bind and block both VEGFR1 and VEGFR2 inhibiting the proliferation of different tumoral cells. We investigated c-Src and STAT3 gene expression changes in murine 4T1 tumors treated by the VGBs. The treated group received 1 and 10 mg kg of the peptides, while the control mice received PBS, intraperitoneally for two weeks. Both of the groups underwent a resection of breast tissue 14 days after treatment. The results of qRT-PCR showed that the expression levels of c-Src and STAT3 genes were significantly decreased, in a dose-dependent manner, after treatment with the different types of VEGF antagonist peptides, compared to the control groups (P < 0.05). The groups treated with 1 mg kg of all three types of VGB showed decreased expression of c-Src and STAT3 less than the groups receiving 10 mg kg of the anti-angiogenic peptides.

Conclusions: In conclusion, peptides VGB1, 3, and 4, could be effective therapeutic molecules in breast cancer by inhibiting angiogenesis and progression of the disease.