DNA topoisomerases are essential nuclear enzymes in correcting topological DNA errors and maintaining DNA integrity.Topoisomerase inhibitors are a significant class of cancer chemotherapeutics with a definite curative...DNA topoisomerases are essential nuclear enzymes in correcting topological DNA errors and maintaining DNA integrity.Topoisomerase inhibitors are a significant class of cancer chemotherapeutics with a definite curative effect.Natural products are a rich source of lead compounds for drug discovery,including anti-tumor drugs.In this study,we found that narciclasine(NCS),an amaryllidaceae alkaloid,is a novel inhibitor of topoisomerase I(topo I).Our data demonstrated that NCS inhibited topo I activity and reversed its unwinding effect on p-HOT DNA substrate.However,it had no obvious effect on topo II activity.The molecular mechanism of NCS inhibited topo I showed that NCS did not stabilize topo-DNA covalent complexes in cells,indicating that NCS is not a topo I poison.A blind docking result showed that NCS could bind to topo I,suggesting that NCS might be a topo I suppressor.Additionally,NCS exhibited a potent anti-proliferation effect in various cancer cells.NCS arrested the cell cycle at G_(2)/M phase and induced cell apoptosis.Our study reveals the antitumor mechanisms of NCS and provides a good foundation for the development of anti-cancer drugs based on topo I inhibition.展开更多
Cancer is a leading cause of death globally, claiming about 9.6 million lives and approximately 420 million new cases of cancer will be diagnosed in the world by the year 2025. The aim of this study was to synthesize ...Cancer is a leading cause of death globally, claiming about 9.6 million lives and approximately 420 million new cases of cancer will be diagnosed in the world by the year 2025. The aim of this study was to synthesize and computationally evaluate pharmacological potential of some derivatives of 9-amino-3-phenylacridone, as topoisomerase II (Topo II) inhibitors. In this study, 10 derivatives of 3-phenyl-9-aminoacridone were chemically synthesized and characterized, and the potential pharmacological indications of these compounds were computationally predicted by methods such as ADMET prediction, molecular target prediction and molecular docking. The results showed that two derivatives (58e and 58j) were non-permeant of blood-brain barrier, and this property was found similar to that of amsacrine and etoposide. The results of molecular docking of the ten derivatives of 3-phenyl-9-aminoacridone that were synthesized in this work showed that the synthetic compounds (58a-j) and the standard drugs have overall best binding affinities for human acetylcholine esterase than butyrylcholinesterase, and overall best binding affinities for human topo IIα than human topo IIβ. Overall, the results of this study suggest that the synthetic compounds 58a, 58c, 58f, 58g, and 58i could probably inhibit topo IIα by catalytic inhibition as seen with amsacrine, but only 58b and 58e possessed DNA non-intercalation properties as seen with etoposide, serving as topo II poison. In conclusion, this study showed that 3-phenyl-9-aminoacridone derivatives are potential inhibitor of topo IIα/β both by catalytic inhibition and poison as non-intercalator of DNA.展开更多
OBJECTIVE The aim of this study is to investigate the inhibitory effects of lapachol on rat C6 glioma both in vitro and in vivo,as well as the potential mechanisms.METHODS First,the model of C6 glioma in Wistar rats w...OBJECTIVE The aim of this study is to investigate the inhibitory effects of lapachol on rat C6 glioma both in vitro and in vivo,as well as the potential mechanisms.METHODS First,the model of C6 glioma in Wistar rats was established and verified by hemotoxylin and eosin staining,immunohistochemical staining and magnetic resonance imaging(MRI).Then different doses of lapachol were gavaged and tumor volumes of the C6 glioma were detected by MRI.The effects of lapachol on C6 cell proliferation,apoptosis and DNA damage were detected by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium(MTS)/phen-azinemethosulfate(PMS)assay,Hoechst33358 staining,AnnexinⅤ-FITC/PI staining,and comet assay.Effects of lapachol on topoisomeraseⅠ(TOPⅠ)and topoisomeraseⅡ(TOPⅡ)activities were detected by TOPⅠand TOPⅡmediated supercoiled p BR322 DNA relaxation assay.Molecular docking was used to predict the interaction of lapachol-TOPⅠand lapachol-TOPⅡ.TOP I and TOPⅡexpression levels in C6 cells were determined by Enzymelinked immunosorbent assay kits and real-time polymerase chain reaction(RT-PCR).RESULTS The rat C6 glioma model was successfully established.High dose lapachol showed significant inhibitory effect on the C6 glioma in Wistar rats(P<0.05).MTS/PMS assay,Hoechst 33258 staining,AnnexinⅤ-FITC/PI staining,and comet assay showed that lapachol could inhibit proliferation,induce apoptosis and DNA damage of C6 cells in dose dependent manners.Lapachol could inhibit the activities of both TOPⅠandⅡ.Molecular docking showed that lapachol-TOPⅠshowed relatively stronger interaction than that of lapachol-TOPⅡ.Enzyme-linked immunosorbent assay and RT-PCR showed that lapachol could inhibit TOPⅡexpression levels,but not TOPⅠexpression levels.CONCLUSION These results showed that lapachol could significantly inhibit C6 glioma both in vivo and in vitro,which might be related with inhibiting TOPⅠand TOPⅡactivities,as wel as TOPⅡexpression.展开更多
OBJECTIVE Lapachol is a natural naphthoquinone compound that possesses extensive biological activities.The aim of this study is to investigate the inhibitory effects of lapachol on rat C6 glioma both in vitro and in v...OBJECTIVE Lapachol is a natural naphthoquinone compound that possesses extensive biological activities.The aim of this study is to investigate the inhibitory effects of lapachol on rat C6 glioma both in vitro and in vivo,as well as the potential mechanisms.METHODS The antitumor effect of lapachol was firstly evaluated in the C6 glioma model in Wistar rats.The effects of lapachol on C6 cell proliferation,apoptosis and DNA damage were detected by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium(MTS)/phenazinemethosulfate(PMS)assay,hoechst 33358 staining,annexinⅤ-FITC/PI staining,and comet assay.Effects of lapachol on topoisomerase I(TOP I)and topoisomeraseⅡ(TOPⅡ)activities were detected by TOPⅠand TOPⅡmediated supercoiled p BR322DNA relaxation assays and molecular docking.TOPⅠand TOPⅡexpression levels in C6 cells were also determined.RESULTS High dose lapachol showed significant inhibitory effect on the C6 glioma in Wistar rats(P<0.05).It was showed that lapachol could inhibit proliferation,induce apoptosis and DNA damage of C6 cel s in dose dependent manners.Lapachol could inhibit the activities of both TOPⅠ and Ⅱ.Lapachol-TOPⅠshowed relatively stronger interaction than that of lapachol-TOPⅡin molecular docking study.Also,lapachol could inhibit TOPⅡexpression levels,but not TOPⅠexpression levels.CONCLUSION These results showed that lapachol could significantly inhibit C6 glioma both in vivo and in vitro,which might be related with inhibiting TOPⅠ and TOPⅡ activities,as wel as TOPⅡ expression.展开更多
The cytotoxic effect of extract of camellia ptilophyllachang(ECPC) and extract of camellia sinensis(ECS) onHeLa cell line, poorly differentiated nasopharyngealcarcinoma cell line(CNE2) and gastric cancer cell line(MGC...The cytotoxic effect of extract of camellia ptilophyllachang(ECPC) and extract of camellia sinensis(ECS) onHeLa cell line, poorly differentiated nasopharyngealcarcinoma cell line(CNE2) and gastric cancer cell line(MGC-803 ) in vitro was studied using MIT assay method.The results showed that ECPC and ECS possessed significantcytotoxic effect on above three cell lines. The anticancer testin mice showed that ECPC had marked inhibitory effectagainst Ehrlich solid carcinoma(ESC) with inhibition ratesof 17. 8 48. 3% and with inhibition rates of 28. 3-54. 5% against reticular cell sarcoma(L2), and that ECShad inhibition rates of 31 . 5 -49. 4 % against ESC and 35. 8- 50% against L2. These two extracts had only marginalinhibitory effect against sarcoma- 180. The unknottingactivity of DNA topoisomerase II was inhibited completelyby ECPC and ECS at the concentration of 50 μg/ mlsuggesting that DNA topoisomerase II might be a targetenzyme of these two extracts.展开更多
Previous phytochemical investigation of the leaves and seeds of Pittosporum angustifolium Lodd.led to the isolation and structural elucidation of polyphenols and triterpene saponins.Evaluation for cytotoxicity of isol...Previous phytochemical investigation of the leaves and seeds of Pittosporum angustifolium Lodd.led to the isolation and structural elucidation of polyphenols and triterpene saponins.Evaluation for cytotoxicity of isolated saponins revealed that the predominant structural feature for a cytotoxic activity are acyl substituents at the oleanane aglycon backbone.The present work reports the results of a screening of 10 selected acylated saponins for their potential to inhibit the human DNA-topoisomerase I,giving rise to IC50 values in a range of 2.8-46.5 lM.To clarify the mode of observed cytotoxic action and,moreover,to distinguish from a pure surfactant effect which is commonly accompanied with saponins,these results indicate an involvement of the topoisomerase I and its role as a possible target structure for a cytotoxic activity.In addition,computational predictions of the fitting of saponins to the topoisomerase I-DNA complex,indicate a similar binding mode to that of clinically used topoisomerase I inhibitors.Graphical Abstract Ten acylated triterpene saponins from Pittosporum angustifolium were investigated for their potential to inhibit the human DNA-topoisomerase I and computational predictions of the fitting of saponins to the topoisomerase I-DNA complex were carried out.展开更多
AIM:rAAV mediated endostatin gene therapy has been examined as a new method for treating cancer.However, a sustained and high protein delivery is required to achieve the desired therapeutic effects.We evaluated the im...AIM:rAAV mediated endostatin gene therapy has been examined as a new method for treating cancer.However, a sustained and high protein delivery is required to achieve the desired therapeutic effects.We evaluated the impact of topoisomerase inhibitors in rAAV delivered endostatin gene therapy in a liver tumor model. METHODS:rAAV containing endostatin expression cassettes were transduced into hepatoma cell lines.To test whether the topoisomerase inhibitor pretreatment increased the expression of endostatin,Western blotting and ELISA were performed.The biologic activity of endostatin was confirmed by endothelial cell proliferation and tube formation assays. The anti-tumor effects of the rAAV-endostatin vector combined with a topoisomerase inhibitor,etoposide,were evaluated in a mouse liver tumor model. RESULTS:Topoisomerase inhibitors,including camptothecin and etoposide,were found to increase the endostatin exPression level in vitro.The over-expressed endostatin, as a result of pretreatment with a topoisomerase inhibitor, was also biologically active.In animal experiments,the combined therapy of topoisomerase inhibitor,etoposide with the rAAV-endostatin vector had the best tumor- suppressive effect and tumor foci were barely observed in livers of the treated mice.Pretreatment with an etoposide increased the level of endostatin in the liver and serum of rAAV-endostatin treated mice.Finally,the mice treated With rAAV-endostatin in combination with etoposide showed the longest survival among the experimental models. CONCLUSION:rAAV delivered endostatin gene therapy in combination with a topoisomerase inhibitor pretreatment is an effective modality for anticancer gene therapy.展开更多
Objective To investigate the expression of topoisomeraseⅡα(TOP2α)in hepatocellular carcinoma(HCC)and its role in predicting prognosis of HCC patients.Methods We used HCC-related datasets in UALCAN,HCCDB,and cBioPor...Objective To investigate the expression of topoisomeraseⅡα(TOP2α)in hepatocellular carcinoma(HCC)and its role in predicting prognosis of HCC patients.Methods We used HCC-related datasets in UALCAN,HCCDB,and cBioPortal databases to analyze the expression and mutation of TOP2αand its co-expressed genes in HCC tissues.GO function and KEGG pathway enrichment of TOP2αand its co-expressed genes were identified.The TIMER database was used to analyze infiltration levels of immune cells in HCC.The impacts of TOP2αand its co-expression genes and the infiltrated immune cells on the survival of HCC patients were assayed by Kaplan-Meier plotter analysis.Results TOP2αand its co-expression genes were highly expressed in HCC(P<0.001)and detrimental to overall survival of HCC patients(P<0.001).TOP2αand its co-expression genes were mainly involved in cell mitosis and proliferation,and cell cycle pathway(ID:hsa04110,P=0.001945).TOP2αand its co-expression genes were mutated in HCC and the mutations were significantly detrimental to overall survival(P=0.0247)and disease-free survival(P=0.0265)of HCC patients.High TOP2αexpression was positively correlated with the infiltration of B cell(r=0.459,P<0.01),CD8^(+)T cell(r=0.312,P<0.01),CD4^(+)T cell(r=0.370,P<0.01),macrophage(r=0.459,P<0.01),neutrophil(r=0.405,P<0.01),and dendritic cell(r=0.473,P<0.01)in HCC.The CD8^(+)T cell infiltration significantly prolonged the 3-and 5-year survival of HCC patients(all P<0.05),and CD4^(+)T cell infiltration significantly shortened the 3-,5-,and 10-year survival of HCC patients(all P<0.05).Conclusion TOP2αmay be an oncogene,which was associated with poor prognosis of HCC patients and could be used as a biomarker for the prognostic prediction of HCC.展开更多
Objective: To study the effect of active compound 6F and A from Pteris semipinnata L.(PsL) on the activities of DNA topoisomerase (TOPO) I and II, activities of cytosolic and membrane TPK, and expression of oncogene c...Objective: To study the effect of active compound 6F and A from Pteris semipinnata L.(PsL) on the activities of DNA topoisomerase (TOPO) I and II, activities of cytosolic and membrane TPK, and expression of oncogene c-myc in lung adenocarcinoma cells. Methods: The effect of compound 6F and A on activities of cytosolic and membrane TPK was measured by scintillation counting; the effect of compound A on expression of oncogene c-myc was determined by flow cytometry indirect fluorimetry. Results: compound 6F and A could inhibit the activities of TOPO I, and they strongly inhibited the TOPO II in 0.01 mg/L and 10.0 mg/L respectively. Compound A slightly inhibited the activities of membrane TPK, but not the cytosolic one. Compound A could inhibit the expression of oncogene c-myc. Conclusion: Topoisomerases are target of compound 6F and A. Compound A could slightly inhibit the activities of TPK, and showed an inhibitory effect on the expression of oncogene c-myc.展开更多
Two new thiosemicarbazone ligands, 2-propionylthiazole ethylthiosemicarbazone (PTZ-ETSC), and 2-propionylthiazole tert-butylthiosemicarbazone (PTZ-tBTSC), along with their two copper(II) complexes, [Cu(PTZ-ETSC)Cl] an...Two new thiosemicarbazone ligands, 2-propionylthiazole ethylthiosemicarbazone (PTZ-ETSC), and 2-propionylthiazole tert-butylthiosemicarbazone (PTZ-tBTSC), along with their two copper(II) complexes, [Cu(PTZ-ETSC)Cl] and [Cu(PTZ-tBTSC)Cl], are reported here for the first time. Once characterized by NMR and MS, these mono-anionic tridentate ligands were reacted with Cu2+ to form the square planar metal complexes [Cu(PTZ-ETSC)Cl] and [Cu(PTZ-tBTSC)Cl]. The x-ray crystal structure of the [Cu(PTZ-tBTSC)Cl] complex shows that the complex adopts a square planar arrangement around the copper(II) ion, but forms a sulfur-bridged dimer in the solid state. Both of the copper complexes displayed strong inhibition of human topoisomerase IIα at activities between 2-4 μM for [Cu(PTZ-ETSC)Cl], and between 8-10 μM for the [Cu(PTZ-tBTSC)Cl] complex. The EC50 values for the MDA-MB-231 breast cancer cell line were 82.6 μM for (PTZ-ETSC), 17.9 μM for [Cu(PTZ- ETSC)Cl], 97.8 μM for (PTZ-tBTSC), and 1.41 μM for [Cu(PTZ-tBTSC)Cl]. The EC50 values for the MCF7 breast cancer cell lines were 9.36 μM for (PTZ-ETSC), 0.13 μM for [Cu(PTZ-ETSC)Cl], 0.333 μM for (PTZ-tBTSC), and 0.093 μM for [Cu(PTZ-tBTSC)Cl].展开更多
The focus of this research is on the study of a series of copper (II) benzoylpyridine thiosemicarbazone complexes. Of the six benzoylpyridine thiosemicarbazone ligands used in this study, two are reported for the firs...The focus of this research is on the study of a series of copper (II) benzoylpyridine thiosemicarbazone complexes. Of the six benzoylpyridine thiosemicarbazone ligands used in this study, two are reported for the first time;2-benzoylpyridine tert-butyl thiosemicarbazone (BZP-tBTSC), and 2-benzoylpyridine benzyl thiosemicarbazone (BZP-BzTSC). Once characterized by NMR, melting point, and MS, these mono-anionic tridentate ligands were then reacted with Cu<sup>2+</sup> to form the new square planar metal complexes [Cu(BZP-tBTSC)Cl] and [Cu(BZP-BzTSC)Cl]. All of the copper complexes display marked inhibition of human topoisomerase IIα. The [Cu(BZP-tBTSC)Cl] complex shows marked activity against human breast cancer cell lines.展开更多
OBJECTIVE To address the molecular implication of Top2 in the context of its interaction with doxorubicin resistance(DXR)genes.METHODS To perform epistasis analyses of top2 with 63genes representing doxorubicin resist...OBJECTIVE To address the molecular implication of Top2 in the context of its interaction with doxorubicin resistance(DXR)genes.METHODS To perform epistasis analyses of top2 with 63genes representing doxorubicin resistance(DXR)genes in fission yeast.Fission yeast cells with single and double mutants were serial diluted and spotted to plates containing 15-75μg·mL-1 doxorubicin.Plates were scanned after 3and 7d.Cell growth was measured and compared between single mutants and double mutants.Nucleus morphology was performed by staining the cells with 4′,6-diamidino-2-phenylindole(DAPI)to observe chromosome segregation.Reverse transcriptase PCR(RT-PCR)was employed to visualize the changes in transcription level and evaluate the stability of chromatin structure.RESULTS Our findings revealed a subset that synergistically collaborate with Top2 to confer DXR and showed that the chromatin-regulating RSC and SAGA complexes act with Top2 in a cluster that is functionally distinct from the Ino80 complex.In various DXR mutants,doxorubicin hypersensitivity was unexpectedly suppressed by a concomitant top2 mutation.Several DXR proteins showed centromeric localization,and their disruption resulted in centromeric defects and chromosome missegregation.An additional top2 mutation could restore centromeric chromatin integrity,suggesting a counterbalance between Top2 and these DXR factors in conferring doxorubicin resistance.CONCLUSION The findings reported here show a functional interaction between Top2 and factors that confer genomic stability at centromeric chromatin under doxorubicin condition.Overall,this molecular basis for mitotic catastrophe associated with doxorubicin treatment will help to facilitate drug combinatorial usage in Doxorubicin-related chemotherapeutic regimens.展开更多
A method of screening assay is demonstrated. The approach is based on the affinity of antitumor candidates for topoisomerases. In this method, antitumor candidates are fished out using topoisomerases as targets. Tradi...A method of screening assay is demonstrated. The approach is based on the affinity of antitumor candidates for topoisomerases. In this method, antitumor candidates are fished out using topoisomerases as targets. Traditional analysis of complex compounds typically encounters signal suppression due to the relatively low concentrations, but enzyme-affinity screening for the active compounds can effectively concentrate the desired analysts into a small volume of high concen-tration. Active compounds are separated from non-affinity compounds by ultrafiltration. The molecules-enzymes complexes that are retained on the filter are subsequently separated by acidification to obtain the topoisomerases-affinity compounds for analysis on High Performance Liquid Chromatography coupled with electrospray ionization mass spectrometric detec-tion (ESI-MS). This enzyme-affinity based screening assay provides a highly specific and efficient method that can directly screen, identify, and acquire drug candidates thus improving the accuracy and speed of high-throughput screening activities.展开更多
C16 saturated fatty acid (Palmitic acid) is one of the most common dietary fatty acids which played an important role in the cellular biological functions. Palmitic acid (PA) was tested for potential inhibition of DNA...C16 saturated fatty acid (Palmitic acid) is one of the most common dietary fatty acids which played an important role in the cellular biological functions. Palmitic acid (PA) was tested for potential inhibition of DNA topoisomerase I (topo I) and it exhibited inhibitory activity in the nanomolar range. Treatment of lung adenocarcinoma cell line A549 with PA resulted in a decrease in cell viability in a concentration-dependent manner, and PA showed cytotoxicity with an IC50 value of 150 μM. DNA fragmentation assay and caspase activity indicated that PA does not induce apoptotic cell death in A549 cells. Finally, we found that PA was able to cause an increase in autophagic flux in a time-dependent manner, evidenced by the accumulation of LC3 through monodansylcadaverine (MDC) staining. More importantly, inhibition of autophagy by blocking autophagosome formation via the inhibition of type III Phosphatidylinositol 3-kinases (PI-3K), by 3-Methyladenine (3-MA) was able to effectively suppress PA-induced autophagy. We showed that inhibition of autophagy sensitized the cells signal to PA-induced apoptosis, suggesting the pro-survival function of autophagy induced by PA. Taken together, results from this study reveal that PA as a topo I inhibitor induced autophagic cell death in A549 cells.展开更多
The activity of DNA topoisomerase Ⅱ prepared from either normal or tumor tissues were compared. It was found that the unknotting activity of the enzyme in malignant tumor cells was higher than that in normal cells. W...The activity of DNA topoisomerase Ⅱ prepared from either normal or tumor tissues were compared. It was found that the unknotting activity of the enzyme in malignant tumor cells was higher than that in normal cells. We selected some antitumor drugs including Chinese traditional medicine, and observed their effects on the unknotting activity of topoisomerase Ⅱ. The results showed that inhibition of the unknotting activity of the enzyme required very low concentrations of drugs, but much higher concentrations were required for other tested. Some antitumor drugs had no effect on the enzyme were also proved. It is interesting that carrageenan, an antiviral drug, strongly blocked the unknotting activity although its antitumor activity has not been reported.展开更多
Cancer of the corpus uteri remains the most common gynecological related cancer in developed countries. Cytology, after the induction of liquid based cytology, has reemerged as a possible first line non-interventional...Cancer of the corpus uteri remains the most common gynecological related cancer in developed countries. Cytology, after the induction of liquid based cytology, has reemerged as a possible first line non-interventional diagnostic procedure with promising results. Apart from slide preparation for cytology diagnosis, LBC allows the application of elaborate molecular tests on the residual material. Samples from 74 symptomatic women were collected in ThinPrep?PreservCyt medium, from witch immunocytochemical and molecular tests were performed. Final diagnosis of 39 endometrioid carcinomas, 20 non-endometrioid carcinomas and 15 non-malignant was set after hysterectomy. Topoisomerase IIa expression was common (42%) in both types of cancer. Promoter methylation analysis revealed that hMLH1 is commonly methylated in cancers (52.7%), CDKN2A and MGMT less often (27.1%) and RARB rarely methylated (8.4%). BRAF activating mutation V600E was a rare event (8.4%) only found in low grade endometrioid carcinomas. Topoisomerase IIa expression correlated with BRAF mutations, hMLH1 and to lesser extent with CDKN2A methylation. Almost none of the biomarkers were positive in cytological negative or hyperplastic without atypia samples. Detection of methylation in any gene displayed sensitivity, specificity, PPV and NPV similar to cytology of cancer. However, inclusion of cytology diagnosis of hyperlasias with atypia increased sensitivity and NPV of cytology outperforming methylation of any gene. Further evaluation of the panel of promoter methylation, especially in cytology diagnoses of hyperplasia with or without atypia should be evaluated since initial results are promising. Even though methylation of MGMT and RARB are rare events, some patients could be benefit from specific chemotherapeutics that target either of them or the more frequently expressed topoisomerase IIa.展开更多
基金the National Natural Science Foundation of China(Grant Nos.21907044,81460559 and 82160697)Yunnan Fundamental Research Projects(Grant Nos.202101AT070155 and 202201AS070086)+2 种基金Basic Research Plan of Yunnan Provincial Science and Technology Department-Kunming Medical University(Grant Nos.202101AY070001-011,202201AY070001-003 and 202101AY070001-041)the Ten Thousand Talent Plans for Young Top-notch Talents of Yunnan Province(Hongyu Zhou,Dandan Liu),Yunnan Academician Expert Workstation(Grant No.202305AF150054)Basic Research Project of Yunnan Provincial Department of Education(Grant No.2022J0213).
文摘DNA topoisomerases are essential nuclear enzymes in correcting topological DNA errors and maintaining DNA integrity.Topoisomerase inhibitors are a significant class of cancer chemotherapeutics with a definite curative effect.Natural products are a rich source of lead compounds for drug discovery,including anti-tumor drugs.In this study,we found that narciclasine(NCS),an amaryllidaceae alkaloid,is a novel inhibitor of topoisomerase I(topo I).Our data demonstrated that NCS inhibited topo I activity and reversed its unwinding effect on p-HOT DNA substrate.However,it had no obvious effect on topo II activity.The molecular mechanism of NCS inhibited topo I showed that NCS did not stabilize topo-DNA covalent complexes in cells,indicating that NCS is not a topo I poison.A blind docking result showed that NCS could bind to topo I,suggesting that NCS might be a topo I suppressor.Additionally,NCS exhibited a potent anti-proliferation effect in various cancer cells.NCS arrested the cell cycle at G_(2)/M phase and induced cell apoptosis.Our study reveals the antitumor mechanisms of NCS and provides a good foundation for the development of anti-cancer drugs based on topo I inhibition.
文摘Cancer is a leading cause of death globally, claiming about 9.6 million lives and approximately 420 million new cases of cancer will be diagnosed in the world by the year 2025. The aim of this study was to synthesize and computationally evaluate pharmacological potential of some derivatives of 9-amino-3-phenylacridone, as topoisomerase II (Topo II) inhibitors. In this study, 10 derivatives of 3-phenyl-9-aminoacridone were chemically synthesized and characterized, and the potential pharmacological indications of these compounds were computationally predicted by methods such as ADMET prediction, molecular target prediction and molecular docking. The results showed that two derivatives (58e and 58j) were non-permeant of blood-brain barrier, and this property was found similar to that of amsacrine and etoposide. The results of molecular docking of the ten derivatives of 3-phenyl-9-aminoacridone that were synthesized in this work showed that the synthetic compounds (58a-j) and the standard drugs have overall best binding affinities for human acetylcholine esterase than butyrylcholinesterase, and overall best binding affinities for human topo IIα than human topo IIβ. Overall, the results of this study suggest that the synthetic compounds 58a, 58c, 58f, 58g, and 58i could probably inhibit topo IIα by catalytic inhibition as seen with amsacrine, but only 58b and 58e possessed DNA non-intercalation properties as seen with etoposide, serving as topo II poison. In conclusion, this study showed that 3-phenyl-9-aminoacridone derivatives are potential inhibitor of topo IIα/β both by catalytic inhibition and poison as non-intercalator of DNA.
文摘OBJECTIVE The aim of this study is to investigate the inhibitory effects of lapachol on rat C6 glioma both in vitro and in vivo,as well as the potential mechanisms.METHODS First,the model of C6 glioma in Wistar rats was established and verified by hemotoxylin and eosin staining,immunohistochemical staining and magnetic resonance imaging(MRI).Then different doses of lapachol were gavaged and tumor volumes of the C6 glioma were detected by MRI.The effects of lapachol on C6 cell proliferation,apoptosis and DNA damage were detected by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium(MTS)/phen-azinemethosulfate(PMS)assay,Hoechst33358 staining,AnnexinⅤ-FITC/PI staining,and comet assay.Effects of lapachol on topoisomeraseⅠ(TOPⅠ)and topoisomeraseⅡ(TOPⅡ)activities were detected by TOPⅠand TOPⅡmediated supercoiled p BR322 DNA relaxation assay.Molecular docking was used to predict the interaction of lapachol-TOPⅠand lapachol-TOPⅡ.TOP I and TOPⅡexpression levels in C6 cells were determined by Enzymelinked immunosorbent assay kits and real-time polymerase chain reaction(RT-PCR).RESULTS The rat C6 glioma model was successfully established.High dose lapachol showed significant inhibitory effect on the C6 glioma in Wistar rats(P<0.05).MTS/PMS assay,Hoechst 33258 staining,AnnexinⅤ-FITC/PI staining,and comet assay showed that lapachol could inhibit proliferation,induce apoptosis and DNA damage of C6 cells in dose dependent manners.Lapachol could inhibit the activities of both TOPⅠandⅡ.Molecular docking showed that lapachol-TOPⅠshowed relatively stronger interaction than that of lapachol-TOPⅡ.Enzyme-linked immunosorbent assay and RT-PCR showed that lapachol could inhibit TOPⅡexpression levels,but not TOPⅠexpression levels.CONCLUSION These results showed that lapachol could significantly inhibit C6 glioma both in vivo and in vitro,which might be related with inhibiting TOPⅠand TOPⅡactivities,as wel as TOPⅡexpression.
文摘OBJECTIVE Lapachol is a natural naphthoquinone compound that possesses extensive biological activities.The aim of this study is to investigate the inhibitory effects of lapachol on rat C6 glioma both in vitro and in vivo,as well as the potential mechanisms.METHODS The antitumor effect of lapachol was firstly evaluated in the C6 glioma model in Wistar rats.The effects of lapachol on C6 cell proliferation,apoptosis and DNA damage were detected by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium(MTS)/phenazinemethosulfate(PMS)assay,hoechst 33358 staining,annexinⅤ-FITC/PI staining,and comet assay.Effects of lapachol on topoisomerase I(TOP I)and topoisomeraseⅡ(TOPⅡ)activities were detected by TOPⅠand TOPⅡmediated supercoiled p BR322DNA relaxation assays and molecular docking.TOPⅠand TOPⅡexpression levels in C6 cells were also determined.RESULTS High dose lapachol showed significant inhibitory effect on the C6 glioma in Wistar rats(P<0.05).It was showed that lapachol could inhibit proliferation,induce apoptosis and DNA damage of C6 cel s in dose dependent manners.Lapachol could inhibit the activities of both TOPⅠ and Ⅱ.Lapachol-TOPⅠshowed relatively stronger interaction than that of lapachol-TOPⅡin molecular docking study.Also,lapachol could inhibit TOPⅡexpression levels,but not TOPⅠexpression levels.CONCLUSION These results showed that lapachol could significantly inhibit C6 glioma both in vivo and in vitro,which might be related with inhibiting TOPⅠ and TOPⅡ activities,as wel as TOPⅡ expression.
文摘The cytotoxic effect of extract of camellia ptilophyllachang(ECPC) and extract of camellia sinensis(ECS) onHeLa cell line, poorly differentiated nasopharyngealcarcinoma cell line(CNE2) and gastric cancer cell line(MGC-803 ) in vitro was studied using MIT assay method.The results showed that ECPC and ECS possessed significantcytotoxic effect on above three cell lines. The anticancer testin mice showed that ECPC had marked inhibitory effectagainst Ehrlich solid carcinoma(ESC) with inhibition ratesof 17. 8 48. 3% and with inhibition rates of 28. 3-54. 5% against reticular cell sarcoma(L2), and that ECShad inhibition rates of 31 . 5 -49. 4 % against ESC and 35. 8- 50% against L2. These two extracts had only marginalinhibitory effect against sarcoma- 180. The unknottingactivity of DNA topoisomerase II was inhibited completelyby ECPC and ECS at the concentration of 50 μg/ mlsuggesting that DNA topoisomerase II might be a targetenzyme of these two extracts.
文摘Previous phytochemical investigation of the leaves and seeds of Pittosporum angustifolium Lodd.led to the isolation and structural elucidation of polyphenols and triterpene saponins.Evaluation for cytotoxicity of isolated saponins revealed that the predominant structural feature for a cytotoxic activity are acyl substituents at the oleanane aglycon backbone.The present work reports the results of a screening of 10 selected acylated saponins for their potential to inhibit the human DNA-topoisomerase I,giving rise to IC50 values in a range of 2.8-46.5 lM.To clarify the mode of observed cytotoxic action and,moreover,to distinguish from a pure surfactant effect which is commonly accompanied with saponins,these results indicate an involvement of the topoisomerase I and its role as a possible target structure for a cytotoxic activity.In addition,computational predictions of the fitting of saponins to the topoisomerase I-DNA complex,indicate a similar binding mode to that of clinically used topoisomerase I inhibitors.Graphical Abstract Ten acylated triterpene saponins from Pittosporum angustifolium were investigated for their potential to inhibit the human DNA-topoisomerase I and computational predictions of the fitting of saponins to the topoisomerase I-DNA complex were carried out.
基金Supported by a faculty research grant of Yonsei University College of Medicine for 2002,No.2002-06
文摘AIM:rAAV mediated endostatin gene therapy has been examined as a new method for treating cancer.However, a sustained and high protein delivery is required to achieve the desired therapeutic effects.We evaluated the impact of topoisomerase inhibitors in rAAV delivered endostatin gene therapy in a liver tumor model. METHODS:rAAV containing endostatin expression cassettes were transduced into hepatoma cell lines.To test whether the topoisomerase inhibitor pretreatment increased the expression of endostatin,Western blotting and ELISA were performed.The biologic activity of endostatin was confirmed by endothelial cell proliferation and tube formation assays. The anti-tumor effects of the rAAV-endostatin vector combined with a topoisomerase inhibitor,etoposide,were evaluated in a mouse liver tumor model. RESULTS:Topoisomerase inhibitors,including camptothecin and etoposide,were found to increase the endostatin exPression level in vitro.The over-expressed endostatin, as a result of pretreatment with a topoisomerase inhibitor, was also biologically active.In animal experiments,the combined therapy of topoisomerase inhibitor,etoposide with the rAAV-endostatin vector had the best tumor- suppressive effect and tumor foci were barely observed in livers of the treated mice.Pretreatment with an etoposide increased the level of endostatin in the liver and serum of rAAV-endostatin treated mice.Finally,the mice treated With rAAV-endostatin in combination with etoposide showed the longest survival among the experimental models. CONCLUSION:rAAV delivered endostatin gene therapy in combination with a topoisomerase inhibitor pretreatment is an effective modality for anticancer gene therapy.
基金This work was partially supported by the Key Project of Natural Science Research of Education Department of Anhui Province(No.KJ2019A0338)Industry-University Cooperation Project of the Ministry of Education(No.202101160001).
文摘Objective To investigate the expression of topoisomeraseⅡα(TOP2α)in hepatocellular carcinoma(HCC)and its role in predicting prognosis of HCC patients.Methods We used HCC-related datasets in UALCAN,HCCDB,and cBioPortal databases to analyze the expression and mutation of TOP2αand its co-expressed genes in HCC tissues.GO function and KEGG pathway enrichment of TOP2αand its co-expressed genes were identified.The TIMER database was used to analyze infiltration levels of immune cells in HCC.The impacts of TOP2αand its co-expression genes and the infiltrated immune cells on the survival of HCC patients were assayed by Kaplan-Meier plotter analysis.Results TOP2αand its co-expression genes were highly expressed in HCC(P<0.001)and detrimental to overall survival of HCC patients(P<0.001).TOP2αand its co-expression genes were mainly involved in cell mitosis and proliferation,and cell cycle pathway(ID:hsa04110,P=0.001945).TOP2αand its co-expression genes were mutated in HCC and the mutations were significantly detrimental to overall survival(P=0.0247)and disease-free survival(P=0.0265)of HCC patients.High TOP2αexpression was positively correlated with the infiltration of B cell(r=0.459,P<0.01),CD8^(+)T cell(r=0.312,P<0.01),CD4^(+)T cell(r=0.370,P<0.01),macrophage(r=0.459,P<0.01),neutrophil(r=0.405,P<0.01),and dendritic cell(r=0.473,P<0.01)in HCC.The CD8^(+)T cell infiltration significantly prolonged the 3-and 5-year survival of HCC patients(all P<0.05),and CD4^(+)T cell infiltration significantly shortened the 3-,5-,and 10-year survival of HCC patients(all P<0.05).Conclusion TOP2αmay be an oncogene,which was associated with poor prognosis of HCC patients and could be used as a biomarker for the prognostic prediction of HCC.
基金the National Natural Science Foundation of China (No. 39870900) and the key project grant from Guangdong Province Science and Te
文摘Objective: To study the effect of active compound 6F and A from Pteris semipinnata L.(PsL) on the activities of DNA topoisomerase (TOPO) I and II, activities of cytosolic and membrane TPK, and expression of oncogene c-myc in lung adenocarcinoma cells. Methods: The effect of compound 6F and A on activities of cytosolic and membrane TPK was measured by scintillation counting; the effect of compound A on expression of oncogene c-myc was determined by flow cytometry indirect fluorimetry. Results: compound 6F and A could inhibit the activities of TOPO I, and they strongly inhibited the TOPO II in 0.01 mg/L and 10.0 mg/L respectively. Compound A slightly inhibited the activities of membrane TPK, but not the cytosolic one. Compound A could inhibit the expression of oncogene c-myc. Conclusion: Topoisomerases are target of compound 6F and A. Compound A could slightly inhibit the activities of TPK, and showed an inhibitory effect on the expression of oncogene c-myc.
文摘Two new thiosemicarbazone ligands, 2-propionylthiazole ethylthiosemicarbazone (PTZ-ETSC), and 2-propionylthiazole tert-butylthiosemicarbazone (PTZ-tBTSC), along with their two copper(II) complexes, [Cu(PTZ-ETSC)Cl] and [Cu(PTZ-tBTSC)Cl], are reported here for the first time. Once characterized by NMR and MS, these mono-anionic tridentate ligands were reacted with Cu2+ to form the square planar metal complexes [Cu(PTZ-ETSC)Cl] and [Cu(PTZ-tBTSC)Cl]. The x-ray crystal structure of the [Cu(PTZ-tBTSC)Cl] complex shows that the complex adopts a square planar arrangement around the copper(II) ion, but forms a sulfur-bridged dimer in the solid state. Both of the copper complexes displayed strong inhibition of human topoisomerase IIα at activities between 2-4 μM for [Cu(PTZ-ETSC)Cl], and between 8-10 μM for the [Cu(PTZ-tBTSC)Cl] complex. The EC50 values for the MDA-MB-231 breast cancer cell line were 82.6 μM for (PTZ-ETSC), 17.9 μM for [Cu(PTZ- ETSC)Cl], 97.8 μM for (PTZ-tBTSC), and 1.41 μM for [Cu(PTZ-tBTSC)Cl]. The EC50 values for the MCF7 breast cancer cell lines were 9.36 μM for (PTZ-ETSC), 0.13 μM for [Cu(PTZ-ETSC)Cl], 0.333 μM for (PTZ-tBTSC), and 0.093 μM for [Cu(PTZ-tBTSC)Cl].
文摘The focus of this research is on the study of a series of copper (II) benzoylpyridine thiosemicarbazone complexes. Of the six benzoylpyridine thiosemicarbazone ligands used in this study, two are reported for the first time;2-benzoylpyridine tert-butyl thiosemicarbazone (BZP-tBTSC), and 2-benzoylpyridine benzyl thiosemicarbazone (BZP-BzTSC). Once characterized by NMR, melting point, and MS, these mono-anionic tridentate ligands were then reacted with Cu<sup>2+</sup> to form the new square planar metal complexes [Cu(BZP-tBTSC)Cl] and [Cu(BZP-BzTSC)Cl]. All of the copper complexes display marked inhibition of human topoisomerase IIα. The [Cu(BZP-tBTSC)Cl] complex shows marked activity against human breast cancer cell lines.
基金The project supported by a Singapore Ministry of Education TierⅡgrant(MOE2010-T2-1-111)awarded to Ee Sin CHEN
文摘OBJECTIVE To address the molecular implication of Top2 in the context of its interaction with doxorubicin resistance(DXR)genes.METHODS To perform epistasis analyses of top2 with 63genes representing doxorubicin resistance(DXR)genes in fission yeast.Fission yeast cells with single and double mutants were serial diluted and spotted to plates containing 15-75μg·mL-1 doxorubicin.Plates were scanned after 3and 7d.Cell growth was measured and compared between single mutants and double mutants.Nucleus morphology was performed by staining the cells with 4′,6-diamidino-2-phenylindole(DAPI)to observe chromosome segregation.Reverse transcriptase PCR(RT-PCR)was employed to visualize the changes in transcription level and evaluate the stability of chromatin structure.RESULTS Our findings revealed a subset that synergistically collaborate with Top2 to confer DXR and showed that the chromatin-regulating RSC and SAGA complexes act with Top2 in a cluster that is functionally distinct from the Ino80 complex.In various DXR mutants,doxorubicin hypersensitivity was unexpectedly suppressed by a concomitant top2 mutation.Several DXR proteins showed centromeric localization,and their disruption resulted in centromeric defects and chromosome missegregation.An additional top2 mutation could restore centromeric chromatin integrity,suggesting a counterbalance between Top2 and these DXR factors in conferring doxorubicin resistance.CONCLUSION The findings reported here show a functional interaction between Top2 and factors that confer genomic stability at centromeric chromatin under doxorubicin condition.Overall,this molecular basis for mitotic catastrophe associated with doxorubicin treatment will help to facilitate drug combinatorial usage in Doxorubicin-related chemotherapeutic regimens.
基金Project supported by the National Natural Science Foundation oChina (No. 20375036) and the Natural Science Foundation of Zhejiang Province (No. RC 0042) China
文摘A method of screening assay is demonstrated. The approach is based on the affinity of antitumor candidates for topoisomerases. In this method, antitumor candidates are fished out using topoisomerases as targets. Traditional analysis of complex compounds typically encounters signal suppression due to the relatively low concentrations, but enzyme-affinity screening for the active compounds can effectively concentrate the desired analysts into a small volume of high concen-tration. Active compounds are separated from non-affinity compounds by ultrafiltration. The molecules-enzymes complexes that are retained on the filter are subsequently separated by acidification to obtain the topoisomerases-affinity compounds for analysis on High Performance Liquid Chromatography coupled with electrospray ionization mass spectrometric detec-tion (ESI-MS). This enzyme-affinity based screening assay provides a highly specific and efficient method that can directly screen, identify, and acquire drug candidates thus improving the accuracy and speed of high-throughput screening activities.
文摘C16 saturated fatty acid (Palmitic acid) is one of the most common dietary fatty acids which played an important role in the cellular biological functions. Palmitic acid (PA) was tested for potential inhibition of DNA topoisomerase I (topo I) and it exhibited inhibitory activity in the nanomolar range. Treatment of lung adenocarcinoma cell line A549 with PA resulted in a decrease in cell viability in a concentration-dependent manner, and PA showed cytotoxicity with an IC50 value of 150 μM. DNA fragmentation assay and caspase activity indicated that PA does not induce apoptotic cell death in A549 cells. Finally, we found that PA was able to cause an increase in autophagic flux in a time-dependent manner, evidenced by the accumulation of LC3 through monodansylcadaverine (MDC) staining. More importantly, inhibition of autophagy by blocking autophagosome formation via the inhibition of type III Phosphatidylinositol 3-kinases (PI-3K), by 3-Methyladenine (3-MA) was able to effectively suppress PA-induced autophagy. We showed that inhibition of autophagy sensitized the cells signal to PA-induced apoptosis, suggesting the pro-survival function of autophagy induced by PA. Taken together, results from this study reveal that PA as a topo I inhibitor induced autophagic cell death in A549 cells.
文摘The activity of DNA topoisomerase Ⅱ prepared from either normal or tumor tissues were compared. It was found that the unknotting activity of the enzyme in malignant tumor cells was higher than that in normal cells. We selected some antitumor drugs including Chinese traditional medicine, and observed their effects on the unknotting activity of topoisomerase Ⅱ. The results showed that inhibition of the unknotting activity of the enzyme required very low concentrations of drugs, but much higher concentrations were required for other tested. Some antitumor drugs had no effect on the enzyme were also proved. It is interesting that carrageenan, an antiviral drug, strongly blocked the unknotting activity although its antitumor activity has not been reported.
文摘Cancer of the corpus uteri remains the most common gynecological related cancer in developed countries. Cytology, after the induction of liquid based cytology, has reemerged as a possible first line non-interventional diagnostic procedure with promising results. Apart from slide preparation for cytology diagnosis, LBC allows the application of elaborate molecular tests on the residual material. Samples from 74 symptomatic women were collected in ThinPrep?PreservCyt medium, from witch immunocytochemical and molecular tests were performed. Final diagnosis of 39 endometrioid carcinomas, 20 non-endometrioid carcinomas and 15 non-malignant was set after hysterectomy. Topoisomerase IIa expression was common (42%) in both types of cancer. Promoter methylation analysis revealed that hMLH1 is commonly methylated in cancers (52.7%), CDKN2A and MGMT less often (27.1%) and RARB rarely methylated (8.4%). BRAF activating mutation V600E was a rare event (8.4%) only found in low grade endometrioid carcinomas. Topoisomerase IIa expression correlated with BRAF mutations, hMLH1 and to lesser extent with CDKN2A methylation. Almost none of the biomarkers were positive in cytological negative or hyperplastic without atypia samples. Detection of methylation in any gene displayed sensitivity, specificity, PPV and NPV similar to cytology of cancer. However, inclusion of cytology diagnosis of hyperlasias with atypia increased sensitivity and NPV of cytology outperforming methylation of any gene. Further evaluation of the panel of promoter methylation, especially in cytology diagnoses of hyperplasia with or without atypia should be evaluated since initial results are promising. Even though methylation of MGMT and RARB are rare events, some patients could be benefit from specific chemotherapeutics that target either of them or the more frequently expressed topoisomerase IIa.