[Corrigendum] Thymoquinone inhibits epithelial­mesenchymal transition in prostate cancer cells by negatively regulating the TGF­ß/Smad2/3 signaling pathway.

After the publication of the article, an interested reader drew to the authors' attention that the Du145 'Control' migration panel in Fig. 2C appeared to overlap with the Du145 'Control' invasion panel in Fig. 5A; furthermore, two of the Du145 panels in Fig. 5A also appeared to overlap. The authors have consulted their original data, and realize that these figures were inadvertently assembled incorrectly. The corrected versions of Figs. 2 and 5, incorporating the correct data for the Du145 'Control' panel in Fig. 2C, and the TQ­/TGF­ß OE­ invasion and migration panels, and the TQ+/TGF­ß OE+ migration panel, in Fig. 5A, are shown on the next page. These further corrections do not grossly affect the results or the conclusions reported in this work. The authors all agree to this Corrigendum, and are grateful to the Editor of Oncology Reports for granting them the opportunity to correct the errors that were made during the assembly of these figures. Lastly, the authors apologize to the readership for any inconvenience these errors may have caused. [Oncology Reports 38: 3592­3598, 2017; DOI: 10.3892/or.2017.6012].

Thymoquinone inhibits metastatic phenotype and epithelial­mesenchymal transition in renal cell carcinoma by regulating the LKB1/AMPK signaling pathway.

Thymoquinone, isolated from the seeds of Nigella sativa, has exhibited antitumor properties in a variety of cancer types. However, few studies have investigated the effect of thymoquinone (TQ) on migration and invasion in renal cell carcinoma (RCC). In the present study, our results confirmed that TQ significantly inhibited the migration and invasion of the human RCC 769­P and 786­O cell lines, as demonstrated by wound healing and Transwell assays. Additionally, TQ upregulated the expression of E­cadherin and downregulated the expression of Snail, ZEB1 and vimentin at the mRNA and protein levels in a concentration­dependent manner. Subsequently, the phosphorylation levels of liver kinase B1 (LKB1) and AMP­activated protein kinase (AMPK) were increased upon TQ treatment. To further validate the role of LKB1/AMPK signaling, we revealed that TQ­mediated increase of E­cadherin level and reduction of Snail level could be further enhanced by LKB1 overexpression. Furthermore, co­treatment with the AMPK inhibitor Compound C attenuated the anti­metastatic effect of TQ on RCC and partially abrogated the high expression of E­cadherin and the low expression of Snail mediated by TQ. In contrast, the AMPK activator AICAR demonstrated the opposite effect. Collectively, the present study revealed that TQ could markedly suppress the metastatic phenotype and reverse the epithelial­mesenchymal transition in RCC by regulating the LKB1/AMPK signaling pathway, indicating that TQ may be a potential therapeutic candidate against RCC.

HMGA2 facilitates epithelial-mesenchymal transition in renal cell carcinoma by regulating the TGF-ß/Smad2 signaling pathway.

High-mobility group AT-hook 2 (HMGA2), a member of the high mobility group family, has been reported to correlate with cancer progression. However, there is no report concerning the correlation between HMGA2 and metastasis in renal cell carcinoma. In the present study, we found that HMGA2 was highly expressed in five renal cell carcinoma cell lines compared with that in the normal renal tubular epithelial HK2 cell line. Additionally, HMGA2 facilitated cell migration and invasion of renal cell carcinoma cells, as evidenced by wound healing and Transwell assays. Subsequently, our results revealed that the E­cadherin level was upregulated, while N­cadherin, Twist1 and Twist2 expression were downregulated in HMGA2-depleted ACHN cells. In contrast, overexpression of HMGA2 in 786­O cells enhanced epithelial-mesenchymal transition (EMT). In addition, analysis of the database Cancer Browser further validated the positive correlation between HGMA2 and Twist1 or Twist2 in renal cell carcinoma. Meanwhile, Kaplan-Meier analysis indicated that low HMGA2 expression was closely associated with an increased overall survival in renal cell carcinoma patients. To confirm the underlying mechanism of HMGA2-regulated EMT, our results revealed that silencing of HMGA2 downregulated the mRNA and protein levels of TGF-ß and Smad2, while HMGA2 overexpression had the opposite effect. Furthermore, TGF-ß overexpression could partially reverse the anti-metastatic effect and mesenchymal-epithelial transition (MET) by HMGA2 loss, while TGF-ß deficiency impeded the pro­metastatic phenotype and high expression of EMT markers induced by HMGA2 overexpression. In summary, our results demonstrated that HMGA2 facilitated a metastatic phenotype and the EMT process in renal cell carcinoma cells in vitro through a TGF-ß-dependent pathway. In addition, these data strongly suggest that HGMA2 may serve as a potential therapeutic target and prognostic biomarker against renal cell carcinoma in the future.

Autophagy induction enhances tetrandrine-induced apoptosis via the AMPK/mTOR pathway in human bladder cancer cells.

Tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the roots of Stephania tetrandra is a traditional Chinese medicine and exerts anticancer capacity in various types of cancers. Previous studies have shown that tetrandrine induces apoptosis in bladder cancer cells via activation of the caspase cascade. However, the underlying mechanism has not yet been reported. Autophagy is a cellular process involved in the degradation of broken proteins and aging organelles to maintain homeostasis. Recent studies indicate that autophagy is implicated in cancer therapy. Thus, we focused on the correlation between autophagy and apoptosis upon tetrandrine treatment in human bladder cancer cells. Firstly, our results observed a marked increase in autophagic double-membrane vacuoles and fluorescent puncta of red fluorescence protein-green fluorescence protein-LC3 (GRP-RFP-LC3) upon tetrandrine treatment, as evidenced by transmission electron microscopy and confocal fluorescence microscopy. Secondly, the expression of LC3-II was increased in tetrandrine-treated T24 and 5637 cells in a time- and concentration-dependent manner. Subsequently, downregulation of p62 and LC3 turnover assay further confirmed that tetrandrine induced autophagic flux in bladder cancer T24 and 5637 cells. Thirdly, the protein levels of phosphorylated-AMP-activated protein kinase (AMPK) and phosphorylated-acetyl-coenzyme A carboxylase (ACC) were upregulated in the tetrandrine-treated cells, while the mammalian target of rapamycin (mTOR)-related proteins were downregulated. Moreover, AICAR, a common AMPK activator, further increased the expression the LC3-II, while AMPK inhibitor compound C partially reversed the LC3-II protein levels in bladder cancer T24 cells. Finally, AICAR significantly reinforced the growth inhibition and apoptosis induction of tetrandrine in T24 and 5637 cells, while compound C had an opposite effect, suggesting that AMPK-mediated autophagy enhanced the cytotoxic and pro-apoptosis effect of tetrandrine in human bladder cancer cells. Taken together, the present study showed that tetrandrine induced autophagy in human bladder cancer cells by regulating the AMPK/mTOR signaling pathway, which contributed to the apoptosis induction by tetrandrine, indicating that tetrandrine may be a potential anticancer candidate for the treatment of bladder cancer, and autophagy may be a possible mechanism for cancer therapy.

Thymoquinone inhibits epithelial-mesenchymal transition in prostate cancer cells by negatively regulating the TGF-ß/Smad2/3 signaling pathway.

Thymoquinone, a major ingredient of black seed oil (Nigella sativa), has been shown to exhibit anticancer capacity in various types of cancers. However, there are few studies concerning the correlation between thymoquinone and epithelial-to-mesenchymal transition (EMT) in prostate cancer. In the present study, we firstly found that thymoquinone showed antimetastatic capacity in prostate cancer DU145 and PC3 cells. Additionally, thymoquinone reversed EMT by increasing E-cadherin expression and decreasing vimentin and Slug expression in a concentration-dependent manner. Recent studies have shown that the transforming growth factor-ß (TGF-ß) signaling pathway may be associated with EMT. Intriguingly, the expression of TGF-ß, Smad2 and Smad3 at the mRNA and protein levels was notably reduced upon thymoquinone treatment in prostate cancer DU145 and PC3 cells. Subsequently, we confirmed that thymoquinone repressed metastasis and EMT of prostate cancer through downregulation of the TGF-ß/Smad2/3 signaling pathway, which may be partially reversed by TGF-ß overexpression. In summary, our findings demonstrated that thymoquinone suppressed the metastatic phenotype and reversed EMT of prostate cancer cells by negatively regulating the TGF-ß/Smad2/3 signaling pathway. These findings suggest that thymoquinone is a potential therapeutic agent against prostate cancer which functions by targeting TGF-ß.