Evaluation of morphology and angiogenesis of breast cancer in BALB/c mice using trypsin inhibitor from Cucumis melo seeds. In vitro and in vivo study

Introduction
Melon seeds, as an excellent source of protease inhibitors, may have a protective role against tumor progression and angiogenesis. However, their effects on angiogenesis and the mechanism of their action against cancer progression remain elusive. This study aimed to investigate the effect of bioactive compounds of melon seed on the expression of angiogenesis genes in BALB/c mice with breast cancer.

Material and methods
Trypsin inhibitor (TI) was purified from the seed powder of Cucumis melo. Half- maximal inhibitory concentration was determined for TI, extract of melon seed powder (EXT), and tamoxifen (TAM) by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test. Also, breast tumor was induced by subcutaneous injection of MC4–L2 cells in BALB/c inbred mice breast tissue. After tumor growth, mice were treated with TI, EXT, and TAM to examine their effects on the tumor characteristics and expression of angiogenesis-related genes including MMP-2, MMP-9, and vascular endothelial growth factor (VEGF) using the reverse transcription polymerase chain reaction method.

Results
Trypsin inhibitor, EXT, TAM, and adjuvant treatment of TI + TAM resulted a reduction in expression of MMP-2, MMP-9, and VEGF. All treatments improved the breast tumor characteristics and the necrosis. The real time polymerase chain reaction method verified the positive effects of the treatments on the breast cancer cell line and tumors.

Conclusions
The results indicated that treatments with TI purified from Cucumis melo seeds and also combination therapy of TI and TAM can be considered as an alternative therapy in breast cancer patients. Further studies are warranted.