Thiostrepton as a Potential Therapeutic Agent for Hepatocellular Carcinoma.

Due to limited drug efficacy and drug resistance, it is urgent to explore effective anti-liver cancer drugs. Repurposing drugs is an efficient strategy, with advantages including reduced costs, shortened development cycles, and assured safety. In this study, we adopted a synergistic approach combining computational and experimental methods and identified the antibacterial drug thiostrepton (TST) as a candidate for an anti-liver cancer drug. Although the anti-tumor capabilities of TST have been reported, its role and underlying mechanisms in hepatocellular carcinoma (HCC) remain unclear. TST was found here to inhibit the proliferation of HCC cells effectively, arresting the cell cycle and inducing cell apoptosis, as well as suppressing the cell migration. Further, our findings revealed that TST induced mitochondrial impairment, which was demonstrated by destroyed mitochondrial structures, reduced mitochondria, and decreased mitochondrial membrane potential (MMP). TST caused the production of reactive oxygen species (ROS), and the mitochondrial impairment and proliferation inhibition of HCC cells were completely restored by the ROS scavenger N-acetyl-L-cysteine (NAC). Moreover, we discovered that TST induced mitophagy, and autophagy inhibition effectively promoted the anti-cancer effects of TST on HCC cells. In conclusion, our study suggests TST as a promising candidate for the treatment of liver cancers, and these findings provide theoretical support for the further development and potential application of TST in clinical liver cancer therapy.

Ciclopirox olamine sensitizes leukemia cells to natural killer cell-mediated cytolysis by upregulating NKG2DLs via the Akt signaling pathway.

The activating receptor natural killer group 2D (NKG2D) expressed by Natural killer (NK) cells functions as a "master-switch" in governing the awakening status of NK cells. The NKG2D-mediated cytotoxicity has been declared to be related with the expression levels of NKG2D ligands (NKG2DLs) expressed on tumor cells. Therefore, selective induction of NKG2DLs could be a reliable approach to enhance the efficacy of NK cell-mediated immunotherapy. Our existing study demonstrated that Ciclopirox Olamine (CPX), an off-patent antifungal agent, effectively elevated the expression of NKG2DLs on leukemia cells and sensitized leukemia cells to NK-cell mediated cytolysis. Induction of ROS production and AKT phosphorylation by CPX is essential for the up-regulation of NKG2DLs expressions. Inhibition of AKT by using AKT inhibitor MK2206 decreased both NKG2DLs expressions and NK cell cytotoxicity. These data indicated that increased sensitivity of CPX-treated leukemia cells to NK cell cytolysis was attributed to higher NKG2DLs expressions, resulting from activated AKT signaling pathway. Our findings support the ongoing development of CPX as an anti-tumor agent and suggest its promising immunotherapeutic value in the medication of leukemia.

USP47 maintains the stemness of colorectal cancer cells and is inhibited by parthenolide.

Colorectal cancer stem cells (CCSCs) are implicated in colorectal tumor initiation, invasion, recurrence and treatment resistance, so elucidation of the mechanism underlying the cancer stem cells induction and development of drugs targeting CCSCs are vital for cancer treatment. Growing evidence shows that dysregulated deubiquitinase (DUBs) expression is frequently associated with stemness and maintenance of cancer stem cells (CSCs). In the current study, we found that upregulation of USP47 is associated with tumorigenesis and poor prognosis in clinical patients with colorectal cancer (CRC). Besides, USP47 was highly expressed in CCSCs enriched by serum-free culture. Further investigation showed that USP47 is closely involved in the maintenance of the stemness of CCSCs. USP47 silencing reduces proliferation and migration of colorectal cancer cells and suppresses the self-renewal of CCSCs by downregulating the expression of cancer stem cell markers, including CD44, CD133, CD166, OCT4 and NANOG. Furthermore, we identified Parthenolide (PTL), a natural sesquiterpene lactone, as a novel USP47 inhibitor. PTL diminishes CCSCs self-renewal and induces apoptosis of CCSCs. Taken together, our findings highlighted a novel DUB involved in the modulation of CCSCs stemness and the potential of PTL in the CRC treatment by targeting CCSCs as the USP47 inhibitor.

Antimicrobial Peptide Brevinin-1RL1 from Frog Skin Secretion Induces Apoptosis and Necrosis of Tumor Cells.

Cancer has always been one of the most common malignant diseases in the world. Therefore, there is an urgent need to find potent agents with selective antitumor activity against cancer cells. It has been reported that antimicrobial peptides (AMPs) can selectively target tumor cells. In this study, we focused on the anti-tumor activity and mechanism of Brevinin-1RL1, a cationic α-helical AMP isolated from frog Rana limnocharis skin secretions. We found that Brevinin-1RL1 preferentially inhibits tumor cells rather than non-tumor cells with slight hemolytic activity. Cell viability assay demonstrated the intermolecular disulfide bridge contributes to the inhibitory activity of the peptide as the antitumor activity was abolished when the disulfide bridge reduced. Further mechanism studies revealed that both necrosis and apoptosis are involved in Brevinin-1RL1 mediated tumor cells death. Moreover, Brevinin-1RL1 induced extrinsic and mitochondria intrinsic apoptosis is caspases dependent, as the pan-caspase inhibitor z-VAD-FMK rescued Brevinin-1RL1 induced tumor cell proliferative inhibition. Immunohistology staining showed Brevinin-1RL1 mainly aggregated on the surface of the tumor cells. These results together suggested that Brevinin-1RL1 preferentially converges on the cancer cells to trigger necrosis and caspase-dependent apoptosis and Brevinin-1RL1 could be considered as a pharmacological candidate for further development as anti-cancer agent.

Cepharanthine suppresses APC-mutant colorectal cancers by down-regulating the expression of ß-catenin.

The aberrant activation of the Wnt/ß-catenin signaling pathway is closely associated with the development of various carcinomas, especially colorectal cancers (CRCs), where adenomatous colorectal polyposis (APC) mutations are the most frequently observed, which limits the anti-tumor efficiency of inhibitors targeting the upstream of Wnt/ß-catenin pathway. The anti-tumor activity of the naturally occurring alkaloid cepharanthine (CEP) extracted from the plant Stephania cepharantha Hayata has been reported in various types of tumors. We previously observed that its derivatives inhibited the Wnt/ß-catenin signaling in liver cancer; however, the specific mechanism remains unknown. In this study, we confirmed CEP can effectively inhibit APC-mutant CRC cell lines (SW480, SW620, LoVo) through disturbing of the Wnt/ß-catenin signaling and elucidated the underlying mechanisms. Here, we demonstrate that CEP attenuates the Wnt/ß-catenin signaling by decreasing the ß-catenin, subsequently impeding the proliferation of APC-mutant CRCs. Moreover, CEP induced ß-catenin transcription inhibition rather than the instability of ß-catenin protein and mRNA contributes to reduction of ß-catenin. Taken together, our findings identify CEP as the first ß-catenin transcriptional inhibitor in the modulation of Wnt/ß-catenin signaling and indicate CEP as a potential therapeutic option for the treatment of APC-mutated CRCs.

Smurf1 and Smurf2 mediated polyubiquitination and degradation of RNF220 suppresses Shh-group medulloblastoma.

Sonic hedgehog (Shh)-group medulloblastoma (MB) (Shh-MB) encompasses a clinically and molecularly distinct group of cancers originating from the developing nervous system with aberrant high Shh signaling as a causative driver. We recently reported that RNF220 is required for sustained high Shh signaling during Shh-MB progression; however, how high RNF220 expression is achieved in Shh-MB is still unclear. In this study, we found that the ubiquitin E3 ligases Smurf1 and Smurf2 interact with RNF220, and target it for polyubiquitination and degradation. In MB cells, knockdown or overexpression of Smurf1 or Smurf2 promotes or inhibits cell proliferation, colony formation and xenograft growth, respectively, by controlling RNF220 protein levels, and thus modulating Shh signaling. Furthermore, in clinical human MB samples, the protein levels of Smurf1 or Smurf2 were negatively correlated with those of RNF220 or GAB1, a Shh-MB marker. Overall, this study highlights the importance of the Smurf1- and Smurf2-RNF220 axes during the pathogenesis of Shh-MB and provides new therapeutic targets for Shh-MB treatment.

Novel PORCN inhibitor WHN-88 targets Wnt/ß-catenin pathway and prevents the growth of Wnt-driven cancers.

Wnt/ß-catenin signaling pathway is a classical and crucial oncogenic pathway in many carcinomas, and Porcupine (PORCN) is an O-acyltransferase, which is indispensable and highly specific for catalyzing palmitoylation of Wnt ligands and facilitating their secretion and biofunction. Targeting PORCN provides a promising approach to specifically cure Wnt-driven cancers from the root. In this study, we designed series of pyridonyl acetamide compounds, and discovered a novel PORCN inhibitor WHN-88 with a unique di-iodinated pyridone structural fragment, which is significantly different from the reported inhibitors. We demonstrated that WHN-88 effectively abolished palmitoylation of Wnt ligands and prevented their secretion and the subsequent Wnt/ß-catenin signaling transduction. Further experiments showed that, at well-tolerated doses, WHN-88 remarkably suppressed the spontaneous occurrence and growth of MMTV-Wnt1 murine breast tumors. Consistently, WHN-88 also notably restrained the progress of xenografted Wnt-driven human tumors, including PA-1 teratocarcinoma with high autocrine Wnt signaling and Aspc-1 pancreatic carcinoma with Wnt-sensitizing RNF43 mutation. Additionally, we disclosed that WHN-88 inhibited cancer cell stemness obviously. Together, we verified WHN-88 is a novel PORCN inhibitor with potent efficacy against the Wnt-driven cancers. Our findings enriched the structural types of PORCN inhibitors, and facilitated the development and application of PORCN inhibiting therapy in clinic.

Cepharanthine hydrochloride inhibits the Wnt/ß­catenin/Hedgehog signaling axis in liver cancer.

Cepharanthine, a biscoclaurine alkaloid isolated from the roots of Stephania cephalantha Hayata, has been reported to demonstrate antitumor activity across multiple cancer types; however, the mechanisms are still under investigation. High transcriptional responses by both the Hedgehog and Wnt pathways are frequently associated with specific human cancers, including liver cancer. To investigate whether these signaling pathways are involved in the pharmaceutical action of cepharanthine, we investigated Hedgehog and Wnt signaling in models of liver cancer treated with a semi­synthetic cepharanthine derivative, cepharanthine hydrochloride (CH), in vitro and in vivo. By using MTT cytotoxic, scratch, Transwell, colony formation and flow cytometry assays, the pharmaceutical effect of CH was assessed. The compound was found to inhibit cellular proliferation and invasion, and promote apoptosis. Subsequent mechanistic investigations revealed that CH suppressed the Hedgehog/Gli1 signaling pathway by inhibiting Gli1 transcription and its transcriptional activity. CH also inhibited Wnt/ß­catenin signaling, and the pathway was found to be an upstream regulator of Hedgehog signaling in CH­treated liver cancer cells. Finally, the antitumor effects of CH were demonstrated in an in vivo xenograft tumor model. Immunohistochemical analysis indicated that Gli1 protein levels were diminished in CH­treated xenografts, compared with that noted in the controls. In summary, our results highlight a novel pharmaceutical antitumor mechanism of cepharanthine and provide support for CH as a clinical therapy for refractory liver cancer and other Wnt/Hedgehog­driven cancers.

Esculetin inhibits endometrial cancer proliferation and promotes apoptosis via hnRNPA1 to downregulate BCLXL and XIAP.

Endometrial cancer represents one of the most common gynecological tumors in the world. Advanced and relapsed patients rely on drug therapy. Therefore, it is extremely important to seek more effective targeted drugs. This study found that esculetin has an anti-tumor effect on endometrial cancer through cellular proliferation and apoptosis. At the same time, its anti-tumor effect has also been verified in human endometrial cancer xenograft models in nude mice. Western blot results showed that BCLXL, XIAP, and pAKT protein expression level were down-regulated. A pulldown experiment and LC-MS/MS analysis technology revealed that esculetin targets the hnRNPA1 protein. Cellular proliferation experiments following si-hnRNPA1 transfection verified the tumor-promoting effect of hnRNPA1 in endometrial cancer cells. Nuclear and cytoplasmic separation experiment demonstrated esculetin affecting the export of the hnRNPA1/mRNA complex from the nucleus into the cytoplasm. Thus, esculetin targets hnRNPA1, thereby downregulates BCLXL and XIAP mRNA transcription and translation, resulting in apoptosis and an arrest in proliferation.

Correction: Cepharanthine hydrochloride reverses the mdr1 (P-glycoprotein)-mediated esophageal squamous cell carcinoma cell cisplatin resistance through JNK and p53 signals.

[This corrects the article DOI: 10.18632/oncotarget.22676.].

Intriguing effects of underlying star topology in Schelling's model with blocks.

We explore the intriguing effects of the underlying star topological structure in the framework of Schelling's segregation model with blocks. The significant consequences exerted by the star topology are both theoretically analyzed and numerically simulated with and without introducing a fraction of altruistic agents, respectively. The collective utility of the model with egoists alone can be optimized and the optimum stationary state is achieved with the underlying star topology of blocks. More surprisingly, once a proportion of altruists is introduced, the average utility gradually decreases as the fraction of altruists increases. This presents a sharp contrast to the results in Schelling's model with a lattice topology of blocks. Furthermore, an adding-link mechanism is introduced to bridge the gap between the lattice and the star topologies and extend our analysis to more general scenarios. A scaling law of the average utility function is found for the star topology of blocks.

Cepharanthine hydrochloride induces mitophagy targeting GPR30 in hepatocellular carcinoma (HCC).

Objectives: Cepharanthine exhibits a wide range of therapeutic effects against numerous cancers by virtue of its pleiotropic mechanisms. However, cepharanthine monotherapy has insufficient drug efficacy for cancers in animal models and clinical trials. The mechanism of its limited efficacy is unknown.Methods: We investigated the possible mechanism for the limited drug efficacy of cepharanthine in cancer therapy using both hepatocellular carcinoma (HCC) primary cells and cell lines, in vitro and in mouse xenograft models.Results: We found that cepharanthine hydrochloride (CH), a semi-synthetic derivative of cepharanthine, induced mitophagy independent of mTOR signaling, and played an AMPK-dependent protective role in the cell fate of HCC in vitro and in vivo. Mechanistically, we demonstrated that CH may bind to GPR30 receptor to activate the subsequent signal cascade involving mitochondrial fission, thus facilitating mitophagy. Therefore, we proposed a new therapeutic regimen for HCC involving CH combined with an autophagy inhibitor. This regimen exhibited remarkable anti-cancer effects in HCC xenograft mouse model.Conclusion: These results identify CH as a new mitophagy inducer targeting GPR30 receptor. The combination therapy of CH and an autophagy inhibitor may become a novel strategy for enhancing the anti-tumor potential of cepharanthine in HCC.

Cepharanthine hydrochloride degrades polyglutamine-expanded androgen receptor proteins through an autophagy pathway in neuron cells.

Cepharanthine is a biscoclaurine alkaloid extracted from Stephania cepharantha that has a variety of biological activities in multiple diseases. Spinal and bulbar muscular atrophy (SBMA) is a late-onset neurodegenerative neuromuscular disease without effective therapy, and the protein toxicity of androgen-dependent polyglutamine-expanded androgen receptor is thought to contribute to its etiology. To determine the therapeutic potential of cepharanthine in SBMA, a murine neuron cell model of SBMA was set up, bearing the human polyglutamine-expanded androgen receptor gene with the Tet-On system. Using this model, we found that the semi-synthetic cepharanthine derivative, cepharanthine hydrochloride (CH), decreased protein levels of polyglutamine-expanded androgen receptor in the cytoplasm and nucleus. Mechanically, CH induced intact autophagy flux and enhanced the clearance of cytoplasmic polyglutamine-expanded androgen receptor, which is different from ubiquitin/proteasome degradation of wild-type androgen receptor. Autophagy induced by CH exhibited cellular protective effects against cytotoxicity of mutant androgen receptor as shown by reduced apoptotic marker and apoptotic cell count. Additionally, activities of cell energy sensor-AMPK signal and intracellular ATP were diminished under CH treatment. In conclusion, this study showed that CH degraded polyglutamine-expanded androgen receptor proteins through an autophagy pathway in neuron cells, resulting in cellular protective effects against toxicity of polyQ expanded proteins. These findings may provide new strategies for the treatment of SBMA and other autophagy-related diseases. Furthermore, the clinical safety and compliance of cepharanthine may make it preferable to current autophagy inducers that may cause undesirable side effects in the treatment of autophagy-related diseases.

Cepharanthine Hydrochloride Improves Cisplatin Chemotherapy and Enhances Immunity by Regulating Intestinal Microbes in Mice.

Chemotherapy is one of the major treatment strategies for esophageal squamous cell carcinoma (ESCC). Unfortunately, most chemotherapeutic drugs have significant impacts on the intestinal microbes, resulting in side effects and reduced efficiency. Therefore, new strategies capable of overcoming these disadvantages of current chemotherapies are in urgent need. The natural product, Cepharanthine hydrochloride (CEH), is known for its anticancer and immunoregulatory properties. By sequencing the V4 region of 16S rDNA, we characterized the microbes of tumor-bearing mice treated with different chemotherapy strategies, including with CEH. We found that CEH improved the therapeutic effect of CDDP by manipulating the gut microbiota. Through metagenomic analyses of the microbes community, we identified a severe compositional and functional imbalance in the gut microbes community after CDDP treatment. However, CEH improved the effect of chemotherapy and ameliorated CDDP treatment-induced imbalance in the intestinal microbes. Mechanically, CEH activated TLR4 and MYD88 innate immune signaling, which is advantageous for the activation of the host's innate immunity to exert a balanced intestinal environment as well as to trigger a better chemotherapeutic response to esophageal cancer. In addition, TNFR death receptors were activated to induce apoptosis. In summary, our findings suggest that chemotherapy of CDDP combined with CEH increased the effect of chemotherapy and reduced the side effects on the microbes and intestinal mucosal immunity. We believe that these findings provide a theoretical basis for new clinical treatment strategies.

Amentoflavone Inhibits HSV-1 and ACV-Resistant Strain Infection by Suppressing Viral Early Infection.

Infection of Herpes simplex virus 1 (HSV-1) induces severe clinical disorders, such as herpes simplex encephalitis and keratitis. Acyclovir (ACV) is the current therapeutic drug against viral infection and ACV-resistant strains have gradually emerged, leading to the requirement for novel antiviral agents. In this study, we exhibited the antiviral activity of amentoflavone, a naturally occurring biflavonoid, toward HSV-1 and ACV-resistant strains. Amentoflavone significantly inhibited infection of HSV-1 (F strain), as well as several ACV-resistant strains including HSV-1/106, HSV-1/153 and HSV-1/Blue at high concentrations. Time-of-drug-addition assay further revealed that amentoflavone mainly impaired HSV-1 early infection. More detailed study demonstrated that amentoflavone affected cofilin-mediated F-actin reorganization and reduced the intracellular transportation of HSV-1 from the cell membrane to the nucleus. In addition, amentoflavone substantially decreased transcription of viral immediate early genes. Collectively, amentoflavone showed strong antiviral activity against HSV-1 and ACV-resistant strains, and amentoflavone could be a promising therapeutic candidate for HSV-1 pathogenesis.

AT-533, a Hsp90 inhibitor, attenuates HSV-1-induced inflammation.

Inflammatory events are tightly associated with the death caused by Herpes simplex virus 1 (HSV-1) infection of the brain. Heat shock protein 90 (Hsp90) is a molecular chaperone that is stimulated in response to many stressful conditions (e.g., inflammation and hypoxia) and Hsp90 inhibitors are suggested to be potent inhibitors of the inflammatory response. The aim of this study was to investigate the effect of Hsp90 inhibitor AT-533 on HSV-1-induced inflammation. AT-533 at a non-antiviral concentration was found to show a prominent inhibitory effect on the production of cytokines induced by HSV-1 infection, such as tumor necrosis factor α (TNF-α), interleukin 6 (IL-6) and interleukin 1ß (IL-1ß). Mechanically, HSV-1 early infection induced inflammation through NF-κB signaling and NLRP3 inflammasome activation, as illustrated by the nuclear translocation of NF-κB and the enhanced cleavage of caspase-1. Besides, HSV-1 enhanced the interaction between NLRP3 and Hsp90. Moreover, AT-533 reduced the nuclear translocation of NF-κB and inflammasome activation via inhibiting the chaperone function of Hsp90. Furthermore, AT-533 inhibited the cleavage of pro-IL-1ß to mature IL-1ß in a NLRP3-independent manner. In summary, AT-533 may be a promising therapeutic strategy in HSV-1-infected inflammation management.

Cepharanthine hydrochloride reverses the mdr1 (P-glycoprotein)-mediated esophageal squamous cell carcinoma cell cisplatin resistance through JNK and p53 signals.

Esophageal squamous cell carcinoma (ESCC) is an aggressive malignancy that is often resistant to therapy. Nowadays, chemotherapy is still one of the main methods for the treatment of ESCC. However, the multidrug resistance (MDR)-mediated chemotherapy resistance is one of the leading causes of death. Exploring agents able to reverse MDR, which thereby increase the sensitivity with clinical first-line chemotherapy drugs, could significantly improve cancer treatment. Cepharanthine hydrochloride (CEH) has the ability to reverse the MDR in ESCC and the mechanism involved have not been reported. The aim of the study was to investigate the potential of CEH to sensitize chemotherapeutic drugs in ESCC and explore the underlying mechanisms by in vitro and in vivo studies. Our data demonstrated that CEH significantly inhibited ESCC cell proliferation in a dose-dependent manner, induced G2/M phase cell cycle arrest and apoptosis, and increased the sensitivity of cell lines resistant to cisplatin (cDDP). Mechanistically, CEH inhibited ESCC cell growth and induced apoptosis through activation of c-Jun, thereby inhibiting the expression of P-gp, and enhancing p21 expression via activation of the p53 signaling pathway. In this study, we observed that growth of xenograft tumors derived from ESCC cell lines in nude mice was also significantly inhibited by combination therapy. To our knowledge, we demonstrate for the first time that CEH is a potentially effective MDR reversal agent for ESCC, based on downregulation of the mRNA expression of MDR1 and P-gp. Together, these results reveal emphasize CEH putative role as a resistance reversal agent for ESCC.