Abstract. Signal transducer and activator of transcription 3 (STAT3) is persistently activated in cancer cells and contributes to malignant progression in various types of cancer. The Janus-activated kinase (JAK) family phosphorylates STAT3 in response to stimulation by cytokines or growth factors. The JAK1-STAT3 signaling pathway plays an important role in cell proliferation and apoptosis. Nitidine chloride (NC) is a benzophenanthridine alkaloid that has been reported as an antitumor agent due to its its inhibitory effects on topoisomerase I. Using a mouse xenograft model of hepatocellular carcinoma (HCC), this study aimed to evaluate the effects of NC on tumor growth in vivo and to elucidate the underlying mechanisms. The analysis of the effects of NC on apoptosis in HCC tumor xenografts in mice was carried out by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay; the expression of Bcl-2, Bax, cyclin-dependent kinase (CDK)4, cyclin D1, p21 and proliferating cell nuclear antigen (PCNA) was analyzed by immunohistochemistry; and the protein expression of JAK1 and STAT3 was examined by western blot analysis. Our results revealed that treatment with NC decreased the tumor volume and tumor weight, suggesting that NC inhibits HCC cell growth in vivo. In addition, NC blocked the activation of JAK1-STAT3 in the tumor tissues, which in turn resulted in the induction of cancer cell apoptosis and the inhibition of proliferation. Consequently, treatment with NC downregulated the expression of cyclin D1, CDK4 and Bcl-2 and increased the level of p21 and Bax. Our data provide a molecular basis for the antitumor activity of NC. IntroductionHepatocellular carcinoma (HCC) is the third leading cause of cancer-related mortality worldwide (1,2) and it has been reported that more than 600,000 individuals succumb to the disease each year (1). It is the second most common cause of cancer-related mortality in China, and 75% of known new cases and deaths in the Asia-Pacific region (3-5). Currently, the main treatment methods for liver cancer include surgical resection, radiotherapy and chemotherapy (4,6). Although surgical resection (which involves removing the tumor completely) offers the best prognosis for long-term survival, only 10-15% of patients are suitable for surgical resection, as the tumor may be too large, or may have grown into major blood vessels or other vital organs (7-9). Related data demonstrate that the percentage of HCC cells is already high at diagnosis with a high expression of the multidrug resistance gene and conventional chemotherapy of HCC fails to provide satisfactory remission and may cause serious side-effects (6,10). Thus, it is necessary to develop a novel effective drug for the treatment of HCC. Natural products have attracted much attention in the search for novel anticancer therapeutic agents as they have relatively few side-effects and have long been used as alternative therapies for various diseases, including cancer (11,12). Therefore, determining naturally occurrin...

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Background/Aims: Ginkgolide B (GB) is currently used as an anticancer drug for treatment of some malignant cancers. However, whether it may have therapeutic effects on bladder cancer remains unknown. Here, we studied the effects of GB on bladder cancer cells. Methods: Bladder cells were treated with different doses of GB, and the effects on ZEB1 and microRNA-223-3p (miR-223-3p) were analyzed by RT-qPCR and/or Western blot. Prediction of a regulatory relationship between miR-93 and 3'-UTR of Beclin-1 mRNA was performed by a bioinformatics algorithm and confirmed by a dual luciferase reporter assay. Results: We found that GB dose-dependently decreased ZEB1 protein, but not mRNA, in bladder cancer cells, resulting in suppression of cell invasion. Moreover, in bladder cancer cells, GB dose-dependently decreased the levels of miR-223-3p, which suppressed the protein translation of ZEB1 through binding to 3'-UTR of ZEB1 mRNA. Overexpression of miR-223-3p decreased ZEB1 protein, while depletion of miR-223-3p increased ZEB1 protein in bladder cancer cells. Conclusion: GB inhibits bladder cancer cell invasiveness through suppressing ZEB1 protein translation via upregulating miR-223-3p.

Epithelial-mesenchymal transition (EMT) of tubular epithelial cells is a key event in renal interstitial fibrosis and the progression of chronic kidney disease (CKD). Apelin is a regulatory peptide involved in the regulation of normal renal hemodynamics and tubular functions, but its role in renal fibrosis remains unknown. In this study, we examined the inhibitory effects of apelin on transforming growth factor-β1 (TGF-β1)-induced EMT in HK-2 cells, and evaluated its therapeutic efficacy in mice with complete unilateral ureteral obstruction (UUO). In vitro, apelin inhibited TGF-β1-mediated upregulation of α-smooth muscle actin (α-SMA) and downregulation of E-cadherin. Increased levels of phosphorylated Smad-2/3 and decreased levels of Smad7 in TGF-β1-stimulated cells were reversed by apelin co-treatment. In the UUO model, administration of apelin significantly attenuated renal interstitial fibrosis, as evidenced by the maintenance of E-cadherin and laminin expression, and markedly suppressed expression of α-SMA, TGF-β1 and its type I receptor, as well as interstitial matrix components. Interestingly, in UUO mice, there was a reduction in the plasma level of apelin, which was compensated by upregulation of APJ expression in the injured kidney. Exogenous supplementation of apelin normalized the level of plasmatic apelin and renal APJ. In conclusion, our study provides the first evidence that apelin is able to ameliorate renal interstitial fibrosis by suppression of tubular EMT through a Smad-dependent mechanism. The apelinergic system itself may promote some compensatory response in the renal fibrotic process. These results suggest that apelin has potential renoprotective effects and may be an effective agent for retarding CKD progression.