Sequential usage of imidazole followed by tamoxifen to enhance the anticancer effect of tamoxifen in estrogen receptor-positive breast cancer cell lines.

Abstract

e15057 Background: In women, breast cancer is the most commonly diagnosed cancer and the leading cause of cancer death worldwide. Tamoxifen is the most commonly used drug for the endocrine treatment of breast cancer. It reduces the risk of recurrence and death from breast cancer when given to estrogen-receptor-positive breast cancer patients. It has recently been shown that imidazoles, an antifungal drug, possess anticancer potentials, and it can be a novel therapeutic in cancer treatment. However, the effects of combined treatment with imidazole and tamoxifen are unknown in estrogen receptor-positive breast cancer cell lines. Our study aimed to investigate the effects of imidazole and tamoxifen combination in estrogen receptor-positive breast cancer cell lines. Methods: MCF7 cell line, an estrogen receptor-positive breast cancer cell line, was used in this study. Following 24 hours 50 mM imidazole (molecular grade) treatment, 15µM tamoxifen was treated to MCF-7 cells by 72 hours. As control groups, following for 24-hour imidazole alone treated, only medium treated cells for 72 hours were used. MTT assay was performed for the determination of cell viability. Apoptosis was shown using acridine orange/ethidium bromide staining. The cellular morphological alterations were observed on bright-field microscopy using Giemsa staining. Cell migration status was determined using by in vitro scratch assay. Results: MTT assay results showed that tamoxifen alone treatment for 72 hours decreased cell viability by 18 percent (p < 0.001). On the other hand, cell viability is not affected by imidazole alone treatment for 24 hours compared with the control group (p > 0.05). However, it was calculated that 24 hours of imidazole followed by tamoxifen for 72 hours decreased cell viability up to 42 percent (p < 0.001). Tamoxifen alone group, compared with combined treatment with tamoxifen and imidazole, observed an increase of apoptotic cell numbers in combined treatment with tamoxifen and imidazole group, statistically significantly (p < 0.01). It was observed that cellular morphology was affected by combined treatment with tamoxifen and imidazole. Giemsa staining results showed that MCF 7 cells changed their cellular morphology, lost cell-cell contact, differentiated from parental morphology and cellular morphology, and appeared unhealthy. Parallel to these findings, a decrease in cell migration was observed in the combined-treated group compared to the tamoxifen alone group (p < 0.01). Conclusions: Our results showed that sequential usage of imidazole followed by tamoxifen has an enhanced anticancer effect of tamoxifen in estrogen receptor-positive breast cancer cell lines. These results allow us to establish a new hormonal treatment for patients with breast cancer.