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-β (TGF-β) signaling pathway may be associated with EMT. Intriguingly, the expression of TGF-β, 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-β/Smad2/3 signaling pathway, which may be partially reversed by TGF-β overexpression. In summary, our findings demonstrated that thymoquinone suppressed the metastatic phenotype and reversed EMT of prostate cancer cells by negatively regulating the TGF-β/Smad2/3 signaling pathway. These findings suggest that thymoquinone is a potential therapeutic agent against prostate cancer which functions by targeting TGF-β.

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.

Oridonin, a bioactive diterpenoid isolated from Rabdosia rubescens, has been reported to exert anticancer activity in various cancers. However, the molecular mechanism of oridonin in thyroid cancer has not yet been elucidated. In the present study, oridonin was found to significantly inhibit migration and invasion of thyroid cancer TPC-1 and BCPAP cells, as evidenced by wound healing assay, transwell migration assay and Matrigel invasion assay. In addition, oridonin could partially impede epithelial-mesenchymal transition by upregulating E-Cadherin expression and downregulating N-Cadherin and vimentin expressions in a concentration-dependent manner. Accumulating evidence indicated that JAK2 (Janus kinase-2)/STAT3 (Signal Transducer and Activator of Transcription 3) signaling pathway was associated with epithelial-mesenchymal transition. As expected, the protein levels of phosphorylated-JAK2 and phosphorylated-STAT3 were dramatically reduced upon oridonin treatment in thyroid cancer TPC-1 and BCPAP cells. Subsequently, the findings revealed that JAK2 overexpression could weaken the anti-metastatic effect and partially attenuate MET (mesenchymal-to-epithelial transition) by oridonin, while AG490, a JAK2 antagonist, enhanced the above process in thyroid cancer cells. The subsequent results showed that oridonin inhibited angiogenesis and VEGFA expression in thyroid cancer cells by tube formation assay, western blot and ELISA assay. Meanwhile, AG490 could further attenuate oridonin-treated VEGFA protein level. In addition, the in vivo results further confirmed that oridonin inhibited tumorigenicity in thyroid cancer xenograft. In conclusion, the results demonstrated that oridonin repressed metastatic phenotype, angiogenesis and modulated EMT (epithelial-mesenchymal transition) of thyroid cancer cells via the inactivation of JAK2/STAT3 signaling pathway, suggesting that JAK2 may be a novel therapeutic target of oridonin against thyroid cancer.

Chemical transdifferentiation is a technique that utilizes small molecules to directly convert one cell type into another without passing through an intermediate stem cell state. This technique offers several advantages over other methods of cell reprogramming, such as simplicity, standardization, versatility, no ethical and safety concern and patient-specific therapies. Chemical transdifferentiation has been successfully applied to various cell types across different tissues and organs, and its potential applications are rapidly expanding as scientists continue to explore new combinations of small molecules and refine the mechanisms driving cell fate conversion. These applications have opened up new possibilities for regenerative medicine, disease modeling, drug discovery and tissue engineering. However, there are still challenges and limitations that need to be overcome before chemical transdifferentiation can be translated into clinical practice. These include low efficiency and reproducibility, incomplete understanding of the molecular mechanisms, long-term stability and functionality of the transdifferentiated cells, cell-type specificity and scalability. In this review, we compared the commonly used methods for cell transdifferentiation in recent years and discussed the current progress and future perspective of the chemical transdifferentiation of somatic cells and its potential impact on biomedicine. We believe that with ongoing research and technological advancements, the future holds tremendous promise for harnessing the power of small molecules to shape the cellular landscape and revolutionize the field of biomedicine.