Thymoquinone Inhibits Tumor Growth and Induces Apoptosis in a Breast Cancer Xenograft Mouse Model: The Role of p38 MAPK and ROS

Abstract

Due to narrow therapeutic window of cancer therapeutic agents and the development of resistance against these agents, there is a need to discover novel agents to treat breast cancer. The antitumor activities of thymoquinone (TQ), a compound isolated from Nigella sativa oil, were investigated in breast carcinoma in vitro and in vivo. Cell responses after TQ treatment were assessed by using different assays including MTT assay, annexin V-propidium iodide staining, Mitosox staining and Western blot. The antitumor effect was studied by breast tumor xenograft mouse model, and the tumor tissues were examined by histology and immunohistochemistry. The level of anti-oxidant enzymes/molecules in mouse liver tissues was measured by commercial kits. Here, we show that TQ induced p38 phosphorylation and ROS production in breast cancer cells. These inductions were found to be responsible for TQ’s anti-proliferative and pro-apoptotic effects. Moreover, TQ-induced ROS production regulated p38 phosphorylation but not vice versa. TQ treatment was found to suppress the tumor growth and this effect was further enhanced by combination with doxorubicin. TQ also inhibited the protein expression of anti-apoptotic genes, such as XIAP, survivin, Bcl-xL and Bcl-2, in breast cancer cells and breast tumor xenograft. Reduced Ki67 and increased TUNEL staining were observed in TQ-treated tumors. TQ was also found to increase the level of catalase, superoxide dismutase and glutathione in mouse liver tissues. Overall, our results demonstrated that the anti-proliferative and pro-apoptotic effects of TQ in breast cancer are mediated through p38 phosphorylation via ROS generation.

Radiation Induced Gastrointestinal Damage and Protection: Nigella Sativa Seed Extract and Thymoquinone

“…Another study also show production of free radicals and P38 phosphorylation. in breast cancer cell line, thus inducing proapoptotic potential 61 .This is just opposite what we observe in normal cells, where it scavenges fRs. Thus it role in normal and cancer cells are different.…”

Thymoquinone chemosensitizes colon cancer cells through inhibition of NF-κB

“…Since then, increasing numbers of studies have focused on TQ in cancer therapy. Numerous in vitro and in vivo studies have investigated the antitumor activity of TQ in several types of cancer (6,14,19,(27)(28)(29)33). In tumor protein p53-null myeloblastic leukemia HL-60 cells, TQ induced apoptosis through an intrinsic signaling pathway (34).…”

“…In human multiple myeloma cells, TQ inhibits proliferation, induces apoptosis and exerts a chemosensitization effect through suppressing signal transducer and activator of transcription 3 (acute-phase response factor) activation (35), and decreases F-actin polymerization and Bcl-2/Bcl-2 like 1 expression (36). TQ-induced apoptosis has been indicated to be mediated by reactive oxygen species generation (29,33,37) and the mitogen-activated protein kinase 14 signaling pathway (33). In 2004, Gali-Muhtasib et al (38) reported that TQ triggered apoptotic cell death in human colorectal cancer cells via a p53-dependent mechanism, and in 2008, Gali-Muhtasib et al (31) demonstrated that TQ triggered inactivation of the stress response pathway sensor checkpoint kinase 1 and contributed to apoptosis in colorectal cancer cells.…”

Effects of Thymoquinone on IL-6 Gene Expression and Some Cellular Signaling Pathways in Prostate Cancer PC3 Cells

“…The experiments were repeated 3 times for each concentration. Then, the cytotoxicity effects of TQ on PC3 cells were assessed by MTT assay (24,25). Briefly, after treating cells for 48 hours, the culture medium was removed and cells were exposed to 100 µL colorless RPMI and 10 µL MTT (5 mg/mL in phosphate buffered saline (PBS) added to each well and incubated for 4 hours.…”