Study of the effect of thymoquinone on increasing the sensitivity to 5-fluorourecil in SW-480 colon cancer cells

Abstract

Recently, various studies have focused on the therapeutic potential of thymoquinone, a natural polyphenol, in various human malignancies, including colorectal cancer. However, the underlying mechanisms in thymoquinone-mediated anti-cancer effects are not yet fully understood. Therefore, the present study investigated the effect of thymoquinone on 5-fluorouracil-induced apoptosis in SW-480 cells. Materials and methods SW-480 cells were treated with 5-fluorouracil, thymoquinone and a combination of both, and cell viability was assessed by MTT assay. MRNA expression of apoptotic markers including Bax, BCL-2 and caspase-9 was assessed using quantitative real-time polymerase chain reaction (qRT-PCR). The rate of apoptosis was measured by annexin V flow cytometry. Western blotting was used to evaluate the expression of γ-H2AX protein. Results 5-Fluorouracil resulted in significant inhibition of cell proliferation by dose-dependent method. The combination of thymoquinone and 5-fluorouracil resulted in a significant inhibition of proliferation compared to single treatments (P <0.05). Thymoquinone also induced apoptosis by regulating pro-apoptotic markers, including Bax and caspase-9, and by reducing anti-apoptotic mediators, including BCL-2. In addition, thymoquinone increased 5-fluorouracil-induced apoptosis in SW-480 cells. 5-Fluorouracil in combination with thymoquinone increased the expression of γ-H2AX protein in SW-480 cells compared with groups treated with thymoquinone and 5-fluorouracil alone.