Search

Background Thymoquinone (TQ), the major active compound isolated from black seed oil ( Nigella sativa ), has been reported to exhibit anti-inflammatory and anticancer abilities. However, the exact molecular mechanism underlying the anticancer effect of TQ is still poorly understood, especially in regard to TQ's effect on endoplasmic reticulum stress-mediated apoptosis. Methods The cytotoxicity of TQ on T24 and 253J bladder cancer cells was analyzed by MTT assay, colony formation assay and Annexin V-FITC/PI staining, while SV-HUC-1, the SV-40 immortalized human uroepithelial cell line, was used as a normal control. The change in mitochondrial membrane potential was assessed by JC-1 staining. mRNA expression and protein expression were detected by qPCR and western blotting. Caspase-3 activity was detected by colorimetric assay. Key finding TQ has a significant cytotoxicity on bladder cancer cells and can inhibit their proliferation and induce apoptosis. The protein changes of Bcl-2, Bax, cytochrome c and endoplasmic reticulum stress-related proteins (GRP78, CHOP, and caspase-12) revealed that the anticancer effect of TQ was associated with mitochondrial dysfunction and the endoplasmic reticulum stress pathway. Pretreatment with a pan-caspase inhibitor, Z-VAD-fmk, or an ER stress inhibitor, 4-PBA, or knockdown of CHOP by shRNA can partly reverse the pro-apoptotic effect of TQ by enhancing the expression of the anti-apoptotic protein Bcl-2, blocking the release of cytochrome c and the translocation of Bax from the cytoplasm to mitochondria. Significance Our findings provide the first demonstration of the anticancer effect of TQ on bladder cancer, and the relationship between ER stress and mitochondrial dysfunction was clearly understood when the apoptosis progressed is revealed. [ABSTRACT FROM AUTHOR]

Epithelial mesenchymal transformation plays a crucial role in the metastasis of bladder cancer, which makes bladder cancer difficult to cure. Bladder cancer is the most common malignancy of the urinary system, and distant metastasis is the leading cause of death. Therefore, finding a bioactive drug that can specifically inhibit epithelial mesenchymal transformation may be a new direction for bladder cancer treatment in the future. Thymoquinone (TQ), the major active compound isolated from black seed oil (Nigella sativa), has been reported to exhibit anti-inflammatory and anticancer abilities. TQ can exhibit its antitumor effect by inhibiting the proliferation and metastasis of cancer cells. However, the underlying mechanism of TQ as a tumor inhibitor in bladder cancer remains poorly understood. First, in this research, we demonstrate that TQ can reverse EMT by upregulating epithelial markers, such as E-cadherin, and downregulating mesenchymal markers, such as N-cadherin and vimentin. Furthermore, we demonstrate that TQ can suppress the activation of the Wnt/β-catenin signaling pathway and inhibit the expression of β-catenin target genes, such as MYC, Axin-2, MMP7, CyclinD1 and MET, which play crucial roles in EMT and cancer progression. Additionally, we demonstrate that TQ can inhibit the growth of xenografts and restrict the formation of tumor metastatic foci in the lung. Taken together, our findings confirm the antimetastatic effect of TQ in bladder cancer cells for the first time and also provide new evidence for the development of TQ as a novel treatment for metastatic bladder cancer. • Thymoquinone inhibits migration and invasion in bladder cancer cells. • Thymoquinone suppresses EMT in bladder cancer cells. • Thymoquinone inhibits the activation of Wnt/β-catenin signaling pathway. • β-catenin plays a key role in EMT inhibition induced by TQ. • Thymoquinone exerts an anti-metastasis effect of bladder cancer in vivo. [ABSTRACT FROM AUTHOR]