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

: One of the most feared complications of childhood cancer treatment is second malignant neoplasms (SMNs). This study evaluates the incidence, risk factors and outcomes of SMNs in a tertiary paediatric oncology centre in Singapore.: A retrospective review was conducted on patients diagnosed with childhood cancer under age 21 and treated at the National University Hospital, Singapore, from January 1990 to 15 April 2012. Case records of patients with SMNs were reviewed.: We identified 1124 cases of childhood cancers with a median follow-up of 3.49 (0 to 24.06) years. The most common primary malignancies were leukaemia (47.1%), central nervous system tumours (11.7%) and lymphoma (9.8%). Fifteen cases developed SMNs, most commonly acute myeloid leukaemia/myelodysplastic syndrome (n = 7). Median interval between the first and second malignancy was 3.41 (0.24 to 18.30) years. Overall 20-year cumulative incidence of SMNs was 5.3% (95% CI, 0.2% to 10.4%). The 15-year cumulative incidence of SMNs following acute lymphoblastic leukaemia was 4.4% (95% CI, 0% to 8.9%), significantly lower than the risk after osteosarcoma of 14.2% (95% CI, 0.7% to 27.7%) within 5 years (<0.0005). Overall 5-year survival for SMNs was lower than that of primary malignancies.: This study identified factors explaining the epidemiology of SMNs described, and found topoisomerase II inhibitor use to be a likely risk factor in our cohort. Modifications have already been made to our existing therapeutic protocols in osteosarcoma treatment. We also recognised the importance of other risk management strategies, including regular long-term surveillance and early intervention for detected SMNs, to improve outcomes of high risk patients.
Bone Neoplasms ; therapy ; Cancer Care Facilities ; Central Nervous System Neoplasms ; therapy ; Follow-Up Studies ; Humans ; Incidence ; Leukemia ; therapy ; Leukemia, Myeloid, Acute ; epidemiology ; Lymphoma ; therapy ; Myelodysplastic Syndromes ; epidemiology ; Neoplasms ; therapy ; Neoplasms, Second Primary ; epidemiology ; Osteosarcoma ; therapy ; Pediatrics ; Retrospective Studies ; Risk Factors ; Singapore ; epidemiology ; Survivors ; statistics & numerical data ; Tertiary Care Centers ; Time Factors ; Topoisomerase II Inhibitors ; therapeutic use

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

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

BACKGROUNDRetinocytoma (RB) is a very common intraocular malignant tumor during infancy. Chemotherapy has gradually been used as the first-line treatment for intraocular RB in recent years. In this study, Livin and PTEN expressions were observed in the RB tissue, along with the growth-inhibiting and apoptosis-induced effects of topotecan (TPT) on RB HXO-Rb44 cell strain. This study aimed to investigate the antigrowth effects of TPT on RB cell strain HXO-Rb44.

METHODSMax-Vision(TM) rapid immunohistochemistry was adopted to detect Livin and PTEN expressions in the normal retina and in RB, and their relationship with RB clinicopathologic features was analyzed. Human RB cell strain HXO-Rb44 was cultivated and passaged. MTT method was used to measure the survival rates of HXO-Rb44 cell strains under various TPT concentrations. IC50 values were calculated. Flow cytometry was used to detect the effects of various TPT concentrations on HXO-Rb44 cell apoptosis. Western blotting was used to detect the differences of Livin and PTEN protein expressions during cell apoptosis.

RESULTSThe positive expressions of Livin and PTEN in the RB group were obviously different from those in the normal control group. In RB tissue, Livin expression was relevant to PTEN expression. TPT could significantly induce the occurrence of cell apoptosis and had a dependent relationship with drug concentration. Livin and PTEN expression levels varied with the extension of the effect time of TPT based on Western blotting analysis.

CONCLUSIONSLivin and PTEN have high and low expression levels in the RB tissue, respectively. Both of them have key roles in RB occurrence and development. TPT could induce human RB cell strain HXO-Rb44 cell apoptosis, and its mechanism is associated with the inhibition of Livin and PTEN expressions.

Adaptor Proteins, Signal Transducing ; analysis ; Apoptosis ; drug effects ; Cell Line, Tumor ; Child ; Child, Preschool ; Dose-Response Relationship, Drug ; Female ; Humans ; Infant ; Inhibitor of Apoptosis Proteins ; analysis ; Male ; Neoplasm Proteins ; analysis ; PTEN Phosphohydrolase ; analysis ; Retinal Neoplasms ; drug therapy ; pathology ; Retinoblastoma ; drug therapy ; pathology ; Topoisomerase I Inhibitors ; pharmacology ; Topotecan ; 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

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

Ataxia-telangiectasia (A-T) is an autosomal recessive disorder characterized by cerebellar ataxia and oculocutaneous telangiectasias. The gene mutated in this disease, ATM (A-T, mutated), encodes a 370-kDa Ser/Thr protein kinase. ATM not only mediates cellular response to DNA damage but also acts as an activator of Akt in response to insulin. However, despite intensive studies, the mechanism underlying the neuronal degeneration symptoms of human A-T is still poorly understood. We found that the topoisomerase inhibitors etoposide and camptothecin readily induced apoptosis in undifferentiated proliferating SH-SY5Y cells but could not induce apoptosis in neuronally differentiated SH-SY5Y cells. In addition, etoposide induced p53 phosphorylation and H2AX foci formation in proliferating SH-SY5Y cells but failed to do so in differentiated SH-SY5Y cells. Moreover, while inhibition of ATM in undifferentiated SH-SY5Y cells partially protected them from etoposide-induced apoptosis, the same treatment had no effect on cell viability in differentiated SH-SY5Y cells. These results suggest that DNA damage or defective response to DNA damage is not the cause of neuronal cell death in human A-T. In contrast, we discovered that Akt phosphorylation was inhibited when ATM activity was suppressed in differentiated SH-SY5Y cells. Furthermore, inhibition of ATM induced apoptosis following serum starvation in neuronally differentiated SH-SY5Y cells but could not trigger apoptosis under the same conditions in undifferentiated proliferating SH-SY5Y cells. These results demonstrate that ATM mediates the Akt signaling and promotes cell survival in neuron-like human SH-SY5Y cells, suggesting that impaired activation of Akt is the reason for neuronal degeneration in human A-T.
Antineoplastic Agents, Phytogenic ; pharmacology ; Apoptosis ; Ataxia Telangiectasia ; pathology ; Ataxia Telangiectasia Mutated Proteins ; Camptothecin ; pharmacology ; Cell Cycle Proteins ; antagonists & inhibitors ; metabolism ; Cell Differentiation ; Cell Line, Tumor ; DNA Damage ; DNA-Binding Proteins ; antagonists & inhibitors ; metabolism ; Etoposide ; pharmacology ; Histones ; metabolism ; Humans ; Morpholines ; pharmacology ; Neuroblastoma ; pathology ; Neurons ; cytology ; Phosphorylation ; Protein-Serine-Threonine Kinases ; antagonists & inhibitors ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Pyrones ; pharmacology ; Signal Transduction ; Topoisomerase Inhibitors ; pharmacology ; Tumor Suppressor Protein p53 ; metabolism ; Tumor Suppressor Proteins ; antagonists & inhibitors ; metabolism

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

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