In vitro anticancer mechanism of a Zn losartan complex

FERRER, EVELINA GLORIA; MARTINEZ, VALERIA; WILLIAMS, PATRICIA ANA MARÍA

La Plata

Workshop; Imaging Techniques for Biotechnology and Biomedical Applications Worshop; 2016

CEQUINOR

Losartan is a drug used in the treatment of hypertension that blocks the angiotensin II receptor (AT1).1 The modification of its structure by metal complexation could change its ability to block the receptor.2 The purpose of this work is to perform a structural modification of the antihypertensive drug losartan by complexation with Zn (II) and to evaluate their anticancer activities on A549 cells in culture. Some of the cytotoxic activities of Losartan and Zn (II) on lung carcinoma cells (A549) have been reported.3-6 The ZnLos complex was obtained and characterized by FTIR, Raman and UV spectroscopies, elemental and thermogravimetric analysis. The cytotoxic effects of ZnSO4, Los and the ZnLos complex on A549 cell line were determined by MTT assay and revealed that both Zn (II) and ZnLos strongly reduced cell viability in a dose-dependent manner. Similarly, the ZnLos complex generated reactive oxygen species (ROS) in cells with glutathione (GSH) depletion and a decrease in the GSH / GSSG ratio. A 500 µM concentration of each compound was selected to study their anticancer mechanisms. Apoptosis was detected using a TUNEL assay by fluorescence microscopy. The percentage of apoptotic A549 cells treated with ZnLos resulted higher than those of control cells and cells treated with ZnSO4 and Losartan. The evaluation was complemented by immunocytochemistry of pro-apoptotic proteins BAX, antiapoptotic BCL-XL and the death executing Caspase-3 determinations, likewise the BAX / BCL-XL ratio was calculated by Western Blot analysis. Morphological changes were observed by microscopy. Cells treated with ZnSO4 and ZnLos became round and the volume shrank. They exhibited apoptotic characteristics such us apoptotic bodies, agglutination and margination of chromatin and cytoplasm vacuolization. The evaluated mechanisms demonstrated that cell death caused by the complex was apoptosis ROS-dependent; however the treatments with the antihypertensive drug Losartan showed induction of cell survival.