Objectives:To investigate the cytotoxic effect of anastrozole on breast (MCF7), liver hepatocellular (HepG2), and prostate (PC3) cancer cells.Methods:This is a prospective study. Anastrozole’s mechanism of apoptosis in living cells was also determined by high content screening (HCS) assay. Methylthiazol tetrazolium (MTT) assay was carried out at the Centre of Biotechnology Research’s, Al-Nahrain University, Baghdad, Iraq between July 2015 and October 2015. The HCS assay was performed at the Centre for Natural Product Research and Drug Discovery, Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia between November 2015 and February 2016.Results:The most significant cytotoxic effect of anastrozole towards 3 cancer cell lines was obtained when its concentration was 400 µg/mL. The MCF7 cells were more sensitive to anastrozole compared with the HepG2 and PC-3 cells. There was a significant increase in membrane permeability, cytochrome c and nuclear intensity when anastrozole (200 µg/mL) was used compared with doxorubicin (20 µg/mL) as a standard. Also, there was a significant decrease in cell viability and mitochondrial membrane permeability when anastrozole (200 µg/mL) was used compared with positive control.Conclusion:Anastrozole showed cytotoxic effects against the MCF7, HepG2, and PC3 cell lines as determined in-vitro by the MTT assay. The HCS technique also showed toxic effect towards MCF7. It is evident that anastrozole inhibits the aromatase enzyme preventing the aromatization mechanism; however, it has a toxic effect.

In this study sixty patients were selected according to a positive estrogen receptor. All of 60 naturally or surgically postmenopausal women that had a diagnosis of breast cancer verified by histology breast cancer. Subdivided to with hormone treatment or without any treatment, Forty patients (group P1) with the ages range from 46 to 75 years, and were being treated with an aromatase inhibitor, Arimidex (1 mg) once daily, and another twenty (group P2) as newly diagnosed of breast cancer with ages ranging from 47 to 75 years. While the age of control ranging from (48-75) years old, used as a reference. Recent investigations have challenged the hypothesis that aromatization of androgens into estrogen is the sole production pathway for estrogens in postmenopausal women. The finding that estradiol persists in the plasma of patients receiving anastrozole treatment despite a near total inhibition of the aromatase enzyme suggests that alternative pathways for estrogen synthesis exist, which appeared in our results, aromatase and estradiol with treatment (452.34pg/ml) and (13.09pg/ml) respectively. An although evidence a positive and strong correlation between aromatase enzyme and estradiol (r=0.573, P=0.00).