Synergistic antitumor effects of HB (berberine alpha-hydroxy-beta-decanoylethyl sulfonate, houttuyn berberine) with HCPT (hydroxycamptothecine), and its correlative mechanism were studied in vitro. MTT assay was employed to determine the cytotoxicity of HB combined with HCPT in tumor cells culture in vitro, IC50 and combination index (CI value) were used to evaluate the synergistic effects. The supercoiled DNA relaxation mediated by topoisomerase I & II was measured by agarose gel electrophoresis assay, and influence of HB was detected. The results showed that HB could inhibit the proliferation of tumor cells (SGC-7901, SW1116 and SW480) in vitro, and the inhibition ratio was increased, IC50 was reduced when combining with HCPT. CI value of the two drugs was less than 1 in HepG2, SW480, SGC-7901 and SW1116 cells. The lowest value was 0.447, 0.626, 0.161 and 0.178 in these tumor cells, respectively, further indicating HB has synergistic action with HCPT on suppressing tumor proliferation. The agarose gel electrophoresis assay showed HB can inhibit topoisomerase I & II activity of SW480 cells at the concentration of 2.0-8.0 mg x L(-1). HCPT is a typical inhibitor of topoisomerase I , the synergistic action between HCPT and HB on suppressing tumor proliferation is perhaps related to the congenerous inhibition of topoisomerase.
Antineoplastic Agents, Phytogenic ; pharmacology ; Berberine ; analogs & derivatives ; pharmacology ; Camptothecin ; analogs & derivatives ; pharmacology ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; DNA Topoisomerases, Type I ; metabolism ; DNA Topoisomerases, Type II ; metabolism ; Drug Synergism ; Humans ; Topoisomerase I Inhibitors ; pharmacology

BACKGROUND: Therapy-related AML (t-AML) occurs as a late complication of chemotherapy administered to treat a prior disorder. Prognostic factors affecting the clinical outcome in t-AML have not yet been clearly defined; therefore, we evaluated these factors in this study. METHODS: Forty-eight patients diagnosed with t-AML within the past 10 years were enrolled, and their chemotherapy regimens categorized into 4 groups: alkylating agents (AK) only, topoisomerase II inhibitors (TI) and AK, TI only, and others. The prognostic factors affecting clinical outcome were evaluated. RESULTS: Five (10.4%), 21 (43.8%), 9 (18.8%), and 13 (27.0%) patients were treated with AK only, AK and TI, TI only, and others, respectively. Patients with an AML M3 phenotype showed significantly longer overall survival (OS; 55.1 vs. 14.3 months, P=0.040) and disease-free survival (DFS; 61.2 vs. 17.5 months, P=0.049) than other phenotypes. In contrast, patients with a complex karyotype showed significantly shorter OS (7.9 vs. 31.3 months, P=0.008) and DFS (9.5 vs. 38.6 months, P=0.046); additionally, patients with chromosome 5 or 7 abnormalities showed significantly shorter OS (9.1 vs. 30.7 months, P=0.011) than other phenotypes. Only the presence of a complex karyotype or AML M3 phenotype retained prognostic impact in a multivariate analysis. CONCLUSION: Only the AML M3 phenotype was identified as having a good prognosis, and this might suggest that it exhibits unique clinical features in t-AML patients. Moreover, our findings indicated that karyotype was the strongest prognostic indicator and predicted a poor prognosis for t-AML patients with a complex karyotype.
Alkylating Agents ; Chromosomes, Human, Pair 5 ; Disease-Free Survival ; Humans ; Karyotype ; Leukemia, Myeloid, Acute ; Phenotype ; Prognosis ; Topoisomerase II Inhibitors

OBJECTIVE: To explore the eff ect of galangin on DNA topoisomerases in lung cancer cells A549 and H46 as well on cell growth. METHODS: The inhibitory effect of galangin on the growth of A549 and H46 cells was analyzed by MTT method. The effect of galangin on Topo I activity was detected by the agarose gel electrophoresis method. Furthermore, the interaction between galangin and Topo I was evaluated by fluorescence spectroscopy. Finally, the eff ect of galangin on the Topo I structure was discussed. RESULTS: Galangin could induce the apoptosis of A549 and H46 cells (IC50 was 0.221 mmol/L and 0.173 mmol/L, respectively). Agarose gel electrophoresis showed that galangin exerted significant inhibitory effect on Topo I activity. Fluorescence spectrum analysis showed that galangin was able to quench Topo I fluorescence, and hydrophobic interaction was the main driving force. Circular dichroism analysis showed that galangin induced Topo I conformation change and increased the content of α-helix, which prevented the formation of active center and in turn led to the decrease in Topo I activity. Molecular simulation results showed that galangin could bind to the active center of Topo I to form hydrogen bonds with the catalytic site at Arg364 and Asn352. CONCLUSION Galangin is able to inhibit Topo I activity and to reduce the unwinding rate of single stranded DNNA in tumor cells, which plays an important role in induction of A549 and H46 cell apoptosis.
Apoptosis ; Cell Cycle ; Cell Line, Tumor ; drug effects ; Cell Proliferation ; DNA Topoisomerases, Type I ; metabolism ; Flavonoids ; chemistry ; Humans ; Lung Neoplasms ; enzymology ; Topoisomerase Inhibitors ; chemistry

OBJECTIVE: To investigate the effects of chemotherapeutic agents widely used in clinical practice on major histocompatibility complex class I-related chain A and B (MICA/B) expression in breast cancer cells, and to explore the molecular mechanisms involved. METHODS: We examined MICA/B mRNA and surface protein expressions in breast cancer cells treated with chemotherapeutic agents by real-time RT-PCR and flow cytometry respectively. The blocking effects of ataxia telangiectasia mutated and Rad3-related kinase (ATM/ATR) inhibitor caffeine and nuclear factor κB (NF-κB) inhibitor pynolidine dithiocarbamate (PDTC) on etoposide-upregulated MICA/B mRNA and surface protein expressions were investigated. Electrophoretic mobility shift assay (EMSA) was taken to investigate whether etoposide enhanced the binding of NF-κB to MICA/B gene promoter. RESULTS: Three topoisomerase inhibitors etoposide, camptothecin and doxorubicine upregulated MICA and MICB mRNA expressions in breast cancer cell MCF-7. Comparing to no-drug-treated cells, MICA mRNA levels increased to (1.68±0.17), (2.54±0.25) and (3.42±0.15) fold, and levels of MICB mRNA increased to (1.82±0.24), (1.56±0.05) and (5.84±0.57) fold respectively in cancer cells treated by etoposide at the concentrations of 5, 20 and 100 μmol/L (P<0.05). MICA and MICB mRNA levels also increased significantly when MCF-7 cells were incubated with camptothecin or doxorubicine at the specific concentrations (P<0.05). MICB mRNA expression also increased slightly in another breast cancer cell SK-BR-3 treated by topoisomerase II inhibitors etoposide and camptothecin (P<0.05). Furthermore, etoposide and camptothecin upregulated MICA/B surface protein expression in MCF-7 cells (P<0.05), and the upregulation was found in both living and apoptotic cells. Our study showed that etoposide induced-MICA/B expression in MCF-7 was inhibited by caffeine at different concentrations. When cancer cells were treated by caffeine with 1, 5 and 10 mmol/L, MICA mRNA levels decreased from (3.75±0.25) to (0.89±0.05), (0.81±0.02) and (0.48±0.04) fold respectively (P<0.001), and MICB mRNA levels decreased from (6.85±0.35) to (1.36±0.13), (0.76±0.06) and (0.56±0.03) fold (P<0.05), while MICA/B protein levels decreased from (3.42±0.05) to (1.32±0.03), (1.21±0.06) and (1.14±0.03) fold (P<0.001), indicating that etoposide-induced MICA/B expression was inhibited by ATM/ATR inhibitor. Similarly, NF-κB inhibitor PDTC also inhibited MICA/B mRNA and protein expressions induced by etoposide significantly when MCF-7 cells were incubated with PDTC at the concentrations of 10, 50 and 100 μmol/L (P<0.05), indicating that NF-κB was also involved in this process. EMSA showed that the binding of NF-κB to MICA/B promoter enhanced in MCF-7 cells after etoposide treatment. CONCLUSION Topoisomerase inhibitor increased MICA/B mRNA and protein expressions in breast cancer cells, indicating that chemotherapeutic agents might increase the recognizing and killing ability of immunocytes to breast cancer cells. ATM/ATR and NF-κB pathways might be involved in it.
Antineoplastic Agents/pharmacology* ; Ataxia Telangiectasia Mutated Proteins/physiology* ; Breast Neoplasms/genetics* ; Cell Line, Tumor ; Doxorubicin ; Etoposide/pharmacology* ; Histocompatibility Antigens Class I ; Humans ; I-kappa B Proteins ; NF-kappa B/physiology* ; RNA, Messenger ; Topoisomerase Inhibitors ; Up-Regulation

Animals ; Antineoplastic Agents ; chemical synthesis ; chemistry ; pharmacology ; Antineoplastic Agents, Phytogenic ; chemical synthesis ; chemistry ; pharmacology ; Camptothecin ; analogs & derivatives ; chemical synthesis ; chemistry ; pharmacology ; DNA Damage ; Humans ; Topoisomerase I Inhibitors ; Topotecan ; chemical synthesis ; chemistry ; pharmacology ; Tumor Cells, Cultured ; drug effects

Adaptor Proteins, Signal Transducing ; analysis ; Apoptosis ; drug effects ; Female ; Humans ; Inhibitor of Apoptosis Proteins ; analysis ; Male ; Neoplasm Proteins ; analysis ; PTEN Phosphohydrolase ; analysis ; Retinal Neoplasms ; drug therapy ; Retinoblastoma ; drug therapy ; Topoisomerase I Inhibitors ; pharmacology ; Topotecan ; pharmacology

OBJECTIVETo compare the mechanisms of G(2)/M cycle arrest induced by topo IIalpha and IIbeta inhibitors in H460 cells.

METHODSThe inhibitory effects of XK469, adriamycin and etoposide on H460 cell growth were analyzed by MTT assay. The changes in cell cycle and expressions of cdc2, phos-cdc2 and 14-3-3sigma proteins induced by these 3 topo II inhibitors were detected by flow cytometry and Western blotting, respectively.

RESULTSBoth of the two types of topo II inhibitor resulted in dose-dependent G(2)/M phase arrest and growth inhibition of H460 cells, but XK469 failed to induce 14-3-3sigma protein expression as adriamycin and etoposide did.

CONCLUSIONTopo IIalpha and topo IIbeta inhibitors induce growth inhibition of H460 cells possibly through two different mechanisms, namely the 14-3-3sigma-dependent pathway and the 14-3-3sigma-independent pathway, but further functional inhibition test of 14-3-3sigma is needed to confirm this hypothesis.

Antigens, Neoplasm ; Carcinoma, Non-Small-Cell Lung ; pathology ; Cell Cycle ; drug effects ; physiology ; Cell Division ; drug effects ; Cell Line, Tumor ; DNA Topoisomerases, Type II ; DNA-Binding Proteins ; antagonists & inhibitors ; G2 Phase ; Humans ; Lung Neoplasms ; pathology ; Quinoxalines ; pharmacology ; Topoisomerase II Inhibitors

Anticonvulsants ; adverse effects ; Aryl Hydrocarbon Hydroxylases ; genetics ; Asian Continental Ancestry Group ; genetics ; Camptothecin ; analogs & derivatives ; metabolism ; Carbamazepine ; adverse effects ; Cytochrome P-450 CYP2C19 ; Glucuronosyltransferase ; genetics ; HLA-A Antigens ; genetics ; HLA-B Antigens ; genetics ; Humans ; Platelet Aggregation Inhibitors ; metabolism ; Stevens-Johnson Syndrome ; genetics ; Ticlopidine ; analogs & derivatives ; metabolism ; Topoisomerase I Inhibitors ; metabolism

MRE11 plays an important role in the signal transduction of DNA damage response, therefore this study was purposed to explore the relationship between hMRE11 focus formation and DNA double-strand breaks (DSBs) caused by etoposide (VP-16) in human promonocytic cells U937. After U937 cells were treated with VP-16, the drug-induced DSBs were assessed by pulsed-field gel electrophoresis (PFGE), the gene transcription levels of hMRE11 were evaluated by RT-PCR, the nuclear focus formation of hMRE11 protein was examined using immunofluorescence technique, the cell cycle in parallel was analyzed by flow cytometry. The results showed that the percentage of U937 cells with DSBs induced by VP-16 raised from 13.0 +/- 2.3% in VP-16 2 microg/ml to 32.0 +/- 4.3% in VP-16 20 microg/ml (P < 0.01) along with increase of VP-16 dose. No difference of the hMRE11 mRNA level in U937 cells following the treatment with 100 microg/ml VP-16 at different times was discovered (P > 0.05). The hMRE11 protein was abundantly and uniformly distributed in the nuclei of untreated U937 cells outside of nucleoli, however, it formed discrete nuclear foci following VP-16 treatment. The mean value of nuclear foci increased by 5 to 20 times following the drug dosing (P < 0.01). An average of 5 nuclear foci per positive nucleus were observed at a dose of 2 microg/ml, and it was increased to an average of over 14 nuclear foci per positive nucleus after treating with VP-16 20 microg/ml. The percentage of nuclei containing hMRE11 nuclear foci also increased from less than 10% after treatment wiht VP-16 2 microg/ml to over 50% after VP-16 20 microg/ml (P < 0.01) following treatment with VP-16. After U937 cells were treated with 100 microg/ml VP-16 for 2 hours and fixed at 4, 8, 12 and 24 hours, the percentage of nuclei with hMRE11 nuclear foci increased to 61.54 +/- 3.6% (the control U937 cells: 0.47 +/- 1.17%, P < 0.01) at 8 hours, with a subsequent decrease in the percentage of nuclear foci-positive cells by 24 hours. The ratio of S-phase U937 cells at 8 hours after being treated with 100 microg/ml VP-16 for 2 hours was 47.55 +/- 2.35%, and that without 100 microg/ml VP-16 was 21.95 +/- 2.91% (P < 0.05). It is concluded that the nuclear focus formation of hMRE11 protein may be a response to DNA damage induced by topoisomerase II inhibitor VP-16 in human promonocytic cell line U937.
Antineoplastic Agents, Phytogenic ; pharmacology ; DNA Damage ; DNA Repair ; genetics ; physiology ; DNA-Binding Proteins ; biosynthesis ; genetics ; metabolism ; physiology ; Dose-Response Relationship, Drug ; Etoposide ; pharmacology ; Humans ; MRE11 Homologue Protein ; Protein Binding ; RNA, Messenger ; biosynthesis ; genetics ; Signal Transduction ; Topoisomerase II Inhibitors ; U937 Cells

Although the anti-malaria drug chloroquine (CQ) has been shown to enhance chemotherapy and radiation sensitivity in clinical trials, the potential mechanisms underlying this enhancement are still unclear. Here, we examined the relevant mechanisms by which the multipotent CQ enhanced the cytotoxicity of topotecan (TPT). The lung cancer cell line A549 was treated with TPT alone or TPT combined with CQ at non-cytotoxic concentrations. Cell viability was assessed using the MTT assay. The percentage of apoptotic cells and the presence of a side population of cells were both determined by flow cytometry. Autophagy and the expression of Bcl-2 family proteins were examined by Western blotting. The accumulation of YFP-LC3 dots and the formation of acidic vesicular organelles were examined by confocal microscopy. CQ sensitized A549 cells to TPT and enhanced TPT-induced apoptosis in a Bcl-2 family protein-independent fashion. CQ inhibited TPT-induced autophagy, which modified the cytotoxicity of TPT. However, CQ failed to modify the transfer of TPT across the cytoplasmic membrane and did not increase lysosomal permeability. This study showed that CQ at non-cytotoxic concentrations potentiated the cytotoxicity of TPT by interfering with autophagy, implying that CQ has significant potential as a chemotherapeutic enhancer.
Apoptosis ; drug effects ; Apoptosis Regulatory Proteins ; metabolism ; Autophagy ; drug effects ; Bcl-2-Like Protein 11 ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Chloroquine ; pharmacology ; Drug Synergism ; Humans ; Lung Neoplasms ; metabolism ; pathology ; Membrane Proteins ; metabolism ; Proto-Oncogene Proteins ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Topoisomerase I Inhibitors ; pharmacology ; Topotecan ; pharmacology ; bcl-2-Associated X Protein ; metabolism