Nakisa Ghamari - Biology Department, Razi University, Kermanshah, Iran
Sajjad Sisakhtnezhad - Biology Department, Razi University, Kermanshah, Iran

Background and Aim: Thymoquinone (TQ), as a major compound of Nigella Sativa seeds, has been reported to possess anti-tumor activity against variety of tumors such as breast cancer. Cobalt II chloride (CoCl۲) is a well-known hypoxia mimetic mediator which induced hypoxia-like responses through the induction of hypoxia-inducible factor-۱ (HIF-۱). The present study conducted to investigate the simultaneous effect of CoCl۲-induced hypoxic condition and TQ treatment on the expression of Sox۲ gene in the cancerous MCF-۷ cell line.Methods: MCF-۷ cells were cultured in T۲۵ flasks in DMEM-F۱۲ medium supplemented with ۱۰% fetal bovine serum. The cultured cells at ۷۰% confluency were treated with CoCl۲ (۱۰۰ μmol/L) as control group and with CoCl۲ and TQ (۵۰۰ ng/ml) as treatment group for ۲۴ h. RNA extraction, DNase I treatment and cDNA synthesis were then performed in control and treatment groups. Finally, quantitative real-time PCR (qRT-PCR) was used to evaluate the expression of Sox۲ gene in treated samples compared to the untreated cells.Results: In this study, the effect of TQ on the mRNA expression of Sox۲ gene involved in the proliferation of MCF-۷ cancerous cell line were evaluated under CoCl۲-induced hypoxic condition. The results of qRT-PCR indicated that TQ at CoCl۲-induced hypoxic condition decreased the expression of Sox۲ gene compared to normoxic condition.Conclusion: SOX۲ protein regulates multiple malignant processes of breast cancer such as promotes cell proliferation and thus tumorigenesis through facilitating the G۱/S transition. According to the results of this study, we conclude that TQ can inhibit MCF-۷ cell line proliferation under hypoxic condition. This study provides a good perspective for further efforts to investigate the effect of TQ on different cancerous cell lines and tumors under hypoxic condition for cancer treatment applications.

Breast cancer, MCF-۷ cell line, Thymoquinone, Cobalt II chloride, Sox۲ gene expression