New 4-imino-4H-Chromeno[2,3-d]Pyrimidin-3(5H)-Amine: Synthesis, Cytotoxic Effects on Tumoral Cell Lines and in Silico ADMET Properties

The synthesis of new 4-imino-4H-chromeno[2,3-d]pyrimidin-3(5H)-amine in four steps including one step under microwave dielectric heating is reported. The structural identity of the synthesized compounds was established according to their spectroscopic analysis, such as FT-IR, NMR and mass spectroscopy. These new compounds were tested for their antiproliferative activities on seven representative human tumoral cell lines (Huh7 D12, Caco2, MDA-MB231, MDA-MB468, HCT116, PC3 and MCF7) and also on fibroblasts. Among them, only the compounds 6c showed micromolar cytotoxic activity on tumor cell lines (1.8 50 50 > 25 μM). Finally, in silico ADMET studies ware performed to investigate the possibility of using of the identified compound 6c as potential anti-tumor compound.

The effect of adenovirus expressing wild-type p53 on 5-fluorouracil chemosensitivity is related to p53 status in pancreatic cancer cell lines

AIM:There are conflicting data about p53 function on cellular sensitivity to the cytotoxic action of 5-fluorouracil (5-FU). Therefore the objective of this study was to determine the combined effects of adenovirus-mediated wild-type (wt) p53 gene transfer and 5-FU chemotherapy on pancreatic cancer cells with different p53 gene status. METHODS:Human pancreatic cancer cell lines Capan-1^(p53mut), Capan-2^(p53wt),FAMPAC^(p53mut),PANC1^(p53mut),and rat pancreatic cancer cell lines AS^(p53wt) and DSL6A^(p53null) were used for in vitro studies.Following infection with different ratios of Ad- p53-particles (MOI) in combination with 5-FU,proliferation of tumor cells and apoptosis were quantified by cell proliferation assay (WST-1) and FACS (PI-staining).In addition,DSL6A syngeneic pancreatic tumor cells were inoculated subcutaneously in to Lewis rats for in vivo studies. Tumor size,apoptosis (TUNEL) and survival were determined. RESULTS:Ad-p53 gene transfer combined with 5-FU significantly inhibited tumor cell proliferation and substantially enhanced apoptosis in all four cell lines with an alteration in the p53 gene compared to those two cell lines containing wt-p53.In vivo experiments showed the most effective tumor regression in animals treated with Ad-p53 plus 5-FU.Both in vitro and in vivo analyses revealed that a sublethal dose of Ad-p53 augmented the apoptotic response induced by 5-FU. CONCLUSION:Our results suggest that Ad-p53 may synergistically enhance 5-FU-chemosensitivity most strikingly in pancreatic cancer cells lacking p53 function.These findings illustrate that the anticancer efficacy of this combination treatment is dependent on the p53 gene status of the target tumor cells.

RADIATION-INDUCED APOPTOSIS OF TWO NASOPHARANGEALCARCINOMA CELL LINES

Objective: To study apoptosis induced by radiation in two nasopharyngeal carcinoma (NPC) cell lines, CNE and CNE-2. Methods: Hoechst 33342 staining, immuno-histochemical staining, RT-PCR, DNA dot blotting and Southern blotting were used to identify apoptosis. Results: A single dose of X-irradiation resulted in apoptosis, the apoptotic index (AI) was time- and dose-dependent. Different apoptotic responses existed in the two cell lines. Immunohistochemical staining showed that bcl-2 protein was strongly positive in CNE but negative in CNE-2. However, RT-PCR revealed p53 mRNA in CNE-2 but not in CNE. P53 and bcl-2 genes were both present in the two cell lines as shown by DNA blotting, but the 2.8 kb fragment of the p53 gene was much lower than the 5.6 kb fragment on CNE which was clearly shown in Southern hybridization, suggestive of partial deletion of p53 gene in CNE. Conclusion: Apoptotic response to radiation is different in two NPC cell lines. CNE is more radioresistant than CNE-2. Overexpression of bcl-2 protein and partial deletion of p53 gene may explain their difference in radiosensitivity.

EFFECT OF ASCORBIC ACID ON DNA SYNTHESIS,INTRACELLULAR ACCUMULATION OF ADM AND ADM RESISTANCE OF TUMOR CELL LINES

Objective: To determine the effect of ascorbic acid (AA) on DNA synthesis, intracellular accumulation of ADM and ADM resistance of tumor cell lines. Methods: K562, K562/ADM and KB cell lines were used to study the effect of ascorbic acid on DNA synthesis, intracellular accumulation of ADM and ADM resistance by fluid scintillometry, MTT method, spectrofluorophotometry and immunocytochemistry. Results: Results showed that AA was capable of inhibiting DNA synthesis of K562 and K562/ADM in a dosedependence fashion, but not KB cell line, and significantly reducing ADM sensitivity in K562 and KB cell lines, as well as potentiating obviously ADM resistance in K562/ADM cell line. Conclusion: These effects of AA may be closely correlated with significant elevation of intracellular accumulation of ADM in KB cell line, and significant reduction of that in K562 and K562/ADM cell lines but possibly not correlated with the expression of Pglycoprotein.

TIME-AND DOSE-DEPENDENT UP-REGULATION OF TNF-α mRNA AFTER IRRADIATION OF HUMAN NSCLC CELL LINES IN VITRO

Objective： Even though radiotherapy plays a major role in the local treatment of non-small cell lung cancer （NSCLC）, little is known about the molecular effects of irradiation in this tumor. In the present study, we examined two NSCLC cell lines for their endogenous production of TNF-α after irradiation. To investigate the radiation-induced TNF-α production in NSCLC cell lines. Methods： Two human NSCLC cell lines （A549： squamous; NCI-H596： adenosquamous） were investigated for their TNF-α mRNA （real-time RT-PCR） after exposure to different irradiation doses （2, 5, 10, 20, 30, 40 Gy） and time intervals （1, 3, 6, 12, 24, 48 or 72 h）. The TNF-α mRNA expression was quantified by real-time RT-PCR. The clonogenic survival was evaluated after irradiation with 2, 4, 6 and 8 Gy. Results： Non-irradiated NSCLC cells exhibited no or very low TNF-α expression. For the NCI-H596 cell line, TNF-α expression was significantly elevated 1～12 h （maximum 6h： 568fold increase relative to unirradiated cells） in a time-dependent manner. The radiation-induced increase could be observed after irradiation with 2 Gy reaching maximal at 40 Gy, with 83 times higher than normal controls. The clonogenic survival of these cell lines was nearly identical. Conclusion： NCI-H596 cells produce significant quantities of TNF-α following irradiation in a time- and dose-dependent manner. The pro-inflammatory cytokine TNF-α is a key mediator for the pathogenesis of radiation pneumonitis. Radiation-induced endogenous TNF-α expression in NSCLC cells may affect the normal lung adjacent to the tumor and may be associated with an adverse clinical outcome of the patient.

3-(Tetrazol-5-yl)-2-imino-coumarins Derivatives: Synthesis, Characterization, and Evaluation on Tumor Cell Lines

The first report of new 3-(tetrazol-5-yl)-2-iminocoumarin derivatives is described. The title compounds were prepared in two steps and were obtained in good yields (55-93%). They have been fully characterized by 1H, 13C NMR, FTIR, UV-Visible and HRMS. They were tested for their antiproliferative activities against six representative human tumor cell lines (Huh 7-D12, Caco2, MDA-MB231, HCT 116, PC3 and NCI-H727) and HaCat keratinocytes. Among them, compound 5e was active on HCT 116 (IC50 15 μM).

STUDY ON EFFECTS OF ARSENIC TRIOXIDE ON GASTRIC CANCER CELL LINES

Objective To evaluate the effects of arsenic trioxide (As-2O-3) on apoptosis and differentiation of gastric cancer cell lines (GCCL). Methods MKN45 and SGC7901 cells were treated with As-2O-3 at different concentrations, then the apoptosis rates and cell cycle were determined by flow cytometry assays, the morphologic changes were observed under fluorescence microscopy and electronic microscopy, and the gene expressions were tested with immunohistologic staining. Results Higher apoptosis rates of GCCL were seen in the As-2O-3-treated group at concentrations of 5μmol and 10μmol, as compared with those in the 5-Fu-treated group. Cell-nuclear pyknosis and chromosomal condensation were observed. The As-2O-3 at a concentration of 0.5 μmol could induce the cell cycle changes of GCCL, revealing an increase in the proportion of G1/G0 phase cells and a decrease in the proportion of S phase cells. From the fifth day after treatment of SGC7901 with As-2O-3 at a low concentration, P53 and bcl-XL genes expression rates were reduced, Bax gene expression rate increased, and bcl-2 gene expression showed little change. Conclusion As-2O-3 could induce GCCL apoptosis at a high concentration and differentiation at a low concentration, but it could not completely reverse the malignant biological behaviours of cancer cells.

Effects of Low Concentrations of Di-(2-ethylhexyl) and Mono-(2-ethylhexyl) Phthalate on Steroidogenesis Pathways and Apoptosis in the Murine Leydig Tumor Cell Line MLTC-1

The aim of this study was to evaluate the effects of low concentrations of DEHP and MEHP on steroidogenesis in a murine Leydig tumor cell line （MLTC-1） in vitro. The result of flow cytometry analysis revealed that the proportion of apoptotic cells was significantly increased after the exposure to DEHP. All three genes （P450scc, P450c17, and 38HSD） under study showed an increased expression following exposure to DEHP or MEHP, although some insignificant inhibitory effects appeared in the 10μmol/L treatment group as compared with the controls. It was also found that DEHP or MEHP stimulated INSL3 mRNA and protein especially in the 0.001 μmol/L treatment group. Testosterone secretions were stimulated after the exposure to DEHP or MEHP. Alterations of steroidogenic enzymes and INSL3 in MLTC-1 cells might be involved in the biphasic effects of DEHP/MEHP on androgen production.

Antineoplastic effects of deoxyelephantopin,a sesquiterpene lactone from Elephantopusscaber, on lung adenocarcinoma (A549) cells

OBJECTIVE： Deoxyelephantopin, a sesquiterpene lactone from Elephantopus scaber, showed inhibition of the growth of various tumor cells in vitro. In the present study, we investigated the cytotoxicity and apoptosis-inducing capacity of deoxyelephantopin on lung adenocarcinoma （A549） cells. METHODS： The cytotoxic effect of deoxyelephantopin on A549 cells and normal lymphocytes was evaluated using 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide （MTT） assay and 50% inhibitory concentration （IC50） value was determined. The self-renewal and proliferating potential of A549 cells after treatment with deoxyelephantopin were examined by colony formation assay. Cellular morphology of deoxyelephantopin-treated cells was observed using phase- contrast microscopy. The induction of apoptosis was evaluated using acddine orange and ethidium bromide staining, Hoechst 33342 staining, terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end-labeling （TUNEL） assay, DNA fragmentation analysis and Annexin V-fluorescein isothiocyanate staining by flow cytometry. Activation of caspases was detected using fluorogenic substrate specific to caspases 2, 3, 8 and 9 and flow cytometric analysis. The total cellular DNA content and expression of cleaved poly （ADP-ribose） polymerase was also analyzed. RESULTS： Deoxyelephantopin exhibited cytotoxicity to A549 cells （IC50 = 12.287 μg/mL）, however, there was no toxicity towards normal human lymphocytes. Deoxyelephantopin suppressed the colony-forming ability of A549 cells in a dose-dependent manner. Acridine orange, ethidium bromide and Hoechst 33342 staining showed cell shrinkage, chromosomal condensation and nuclear fragmentation, indicating induction of apoptosis. Deoxyelephantopin increased apoptosis of A549 cells, as evidenced by more TUNEL-positive cells. DNA fragmentation and Annexin V staining revealed late-stage apoptotic cell population. Deoxyelephantopin inhibited A549 cell growth by cell cycle arrest at G2/M phase and induced apoptosis through both extrinsic and intrinsic pathways. CONCLUSION： These results suggest that deoxyelephantopin has great potential as a new chemotherapeutic agent to be developed further for the treatment of lung cancer.

Effect of a nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester on invasion of human colorectal cancer cell line SL-174T

AIML To investigate the effect and mechanism of action of the nitric oxide synthase （NOS） inhibitor NG-nitro-L-arginine methyl ester （L-NAME） on invasion and metastasis of human colorectal cancer cell line SL-174T. METHODS： Human colorectal cancer cel4 line SL-174T was cultured and treated separately with four different dosages of L-NAME for 72 h, Nitric oxide （NO） production was measured with Griess reagent, The effect of L-NAME on invasion and migration of SL-174T cells were evaluated by using Transwell chambers attached with polycarbonate filters and reconstituted basement membrane （Matrigel）, RT-PCR was performed to determine the mRNA levels of matrix metalloproteinase-2 （MMP-2） and tissue inhibitor metalloproteinase-2 （TIMP-2）,RESULTS： L-NAME could significantly inhibit NO production of SL-174T in a dose-dependent manner. After being treated for 72 h with 0.2, 0.4, 0.8, and 1.0 mmol/L L- NAME, respectively, the ability of the L-NAME treated SL- 174T cells to invade the reconstituted basement membrane decreased significantly （t = 8.056, P〈0.05; t= 14.467, P〈0.01; t= 27.785, P〈0.01; and t= 29.405, P〈0.01, respectively） and the inhibition rates were 10.29%, 19.62%, 34.08%, and 42.23%, respectively. Moreover, L-NAME could inhibit migration of SL-174T cells, and the inhibition rates were 20.76%, 24.95%, 39.43%, and 46. 85% for L-NAME at 0.2, 0.4, 0.8, and 1.0 mmol/L, respectively （t = 15.116, P〈0.01）. In addition, after treatment with L-NAME, expression of MMP-2 mRNA was significantly decreased （t = 71.238, P〈0.01） and that of TIMP-2 mRNA was markedly increased （t = -13.020, P〈0.01）. CONCLUSION： L-NAME exerts anti-invasive and anti- metastatic effects on SL-174T cell line via downregulating MNP-2 mRNA expression and upregulating TIMP-2 mRNA expression.

Effects of endostatin on expression of vascular endothelial growth factor and its receptors and neovascularization in colonic carcinoma implanted in nude mice

AIM:To investigate the antiangiogenic effects of endostatin on colonic carcinoma cell line implanted in nude mice and its mechanism. METHODS:Nude mice underwent subcutaneous injection with LS-174t colonic carcinoma cell line to generate carcinoma and were randomly separated into two groups.Mice received injection of vehicle or endostatin every day for two weeks. After the tumor was harvested,the tumor volumes were determined,and the expressions of CD34,VEGF and FIk-1 were examined by immunohistochemical method. RESULTS:Tumor volume was significantly inhibited in the endostatin group(84.17%)and tumor weight was significantly inhibited in the endostatin group(0.197±0.049) compared to the control group(1.198±0.105)(F=22.56, P=0.001),microvessel density(MVD)was significantly decreased in the treated group(31.857±3.515)compared to the control group(100.143±4.290)(F=151.62,P<0.001). Furthermore,the expression of FIk-1 was significantly inhibited in the treated group(34.29%) ompared to the control group(8.57%)(X^2=13.745,P=0.001).However no significant decrease was observed in the expression of vascular endothelial growth factor(VEGF)between these two groups(X^2=0.119,P=0.730). CONCLUSION:Endostatin can inhibit tumor growth and angiogenesis by blocking Vegf/FIk-1 pathway.This experiment provides the theory basis for developing a new anti-carcinoma drug through studying the properties of anti-angiogenesis inhibitors.

Adeno-associated virus mediated endostatin gene therapy in combination with topoisomerase inhibitor effectively controls liver tumor in mouse model

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.

DEPLETION OF O^6-METHYLGUANINE-DNA METHYLTRANSFERASE ACTIVITY AND POTENTIATION OF 1-(4-AMINO-2-METHYL-5- PYRIMIDINYL) METHYL-3 (2-CHLOROETHYL)-3-NITRO- SOUREA ANTITUMOR EFFECT BY STREPTOZOTOCIN

O6-methylguanine-DNA Methyltransferase (MGMT) can specifically repair the DNA demage Induced by chioroethylnitrosoureas (CENU) such at 1-(4-amino-2-methyt-pyrlmidinyl) methyl-3-(2-chloroethyl-)-3-nitrosourea (ACNU), constituting the molecular basis of tumor cell resistance to CENU. The present study demonstrated that sensitization of resistant tumor cells to ACNU could be achieved by streptozotocin (STZ) treatment which could deplete MGMT activity in vitro and in vivo. It suggested that depletion of the molecular basis of tumor cell resistance to chemotherapeutic agents might be a practicable way to improve the effectiveness of tumor chemotherapy.

Mutations of mitochondrion DNA in mouse tumors

Objective： To ascertain the variations of mitochondrion DNA （mtDNA） in mouse tumors and to inquire into the relationship between mutations of mtDNA and carcinogenesis Methods： The variations of D-loop, ND3 and tRNA^Met＋Glu＋Ile gene fragments of mtDNA from six tumor cell lines of mice were analyzed by PCR technology with restriction fragment length polymorphism analysis （polymerase chain reaction-restriction fragment length polymorphism, PCR-RFLP） and single strand conformation polymorphism analysis （SSCP-PCR） method. Results： ND3 and tRNA^Met＋Glu＋Ile gene fragments ofmtDNA from the tumors showed no variation in 27 endonuclease sites; D-loop ofmtDNA from Hca-F had an additional endonuclease sites of Hinf I in contrast to that of the inbred mouse. Deeply analyzed by PCR-SSCP, the D-loop ofmtDNA was found to possess mutations in 4 of 6 tumors. Conclusion： D-loop is the hot spot of tumor mtDNA mutation which can act as contributors to the carcinogenic

Preliminary Findings on Anticancer and Lymphocyte Stimulated Activities of Bioactive Compounds Extracted from Vietnam Carica papaya Leaves

In this study, the target bioactive compounds （e.g., alkaloids, flavonoids, saponins and other polar compounds） in Vietnamese Caricapapaya leaves were extracted. The cytotoxic activities of the papaya leaves extracts on the selected tumor cell lines, such as lung cancer cell line LU-1, carcinoma cell line KB, breast cancer cells MCF7 and leukemia cell line HL-60, were examined. Preliminary findings showed a high inhibitive activity of papaya leave extracts against the four tested tumor cell lines at the concentration of 100 μg/mL. Out of the bioactive compounds in papaya leaves extract, alkaloids showed the highest inhibitive activity （105.95% on MCF7 and 91.86% on LU-1）, followed by polar compounds （62.88% on LU-1 and 21.80% on KB）, and saponins （59.74% on MCF7 and 25.25% on LU-1）. Flavonoids has the lowest inhibitive activity on cell lines （e.g., 45.51% on MCF7 and 20.32% on LU-1）. Taken together, the results suggest that alkaloids have a relatively high inhibitive activity on the selected tumor cell lines and their stimulated concentration at 50% （IC50） values for on MCF7 and KB were 24.67 μg/mL and 33.56 μg/mL, respectively. However, the result pointed out the immunostimulatory ability of only polar compounds and saponins which could stimulate the growth of in vitro lymphocytes but not flavonoids and alkaloids. The SC50 （stimulated concentration at 50%） values of polar compounds and saponins were 287.87μg/mL and 192.99 μg/mL, respectively.

Effect of berberine on activity and mRNA expression of N-acetyl transferase in human lung cancer cell line A549

OBJECTIVE： To study the effects of berberine on ac- tivity and mRNA expression of N-acetyltransferase in human lung cancer cell line A549. METHODS： N-acetyltransferase antibodies wereprepared. The human lung cancer A549 cells were cultivated randomly in the wells of culture plate, and divided into the control group, and berberine 0.0008, 0.008, 0.08, 0.8 and 1.6 mM treatment groups, with 3 wells for each group. 24 h later, A549 cells in each group were collected respectively, the content of N-acetyltransferase was detected by Flow cytometry, and the mRNA expression of N-acetyltransferase was observed by reverse tran- scription polymerase chain reaction. RESULTS The N-acetyltransferase content in hu- man lung cancer A549 cells decreased with the in- creasing of berberine concentration, significantly lower than that in the control group （P〈O.05 or P〈 0.001）; and the mRNA expression of N-acetyltrans- ferase also decreased with the increasing of berber- ine concentration, significantly lower in Huanglian- su treatment groups （P〈0.O01）. CONCLUSION： Berberine can inhibit the activity of N-acetyltransferase in human lung cancer cell line A549, and shows negative correlations of dose and time in a certain extent. The inhibited gene expres- sion of N-acetyltransferase in human lung cancer A549 cell may probably represent one of the mech- anisms for its antineoplastic effect.

Curcumin co-treatment ameliorates resistance to gefitinib in drug-resistant NCI-H1975 lung cancer cells

OBJECTIVE: To examine whether a combinative treatment with curcumin enhances the effects of the epidermal growth factor receptor-tyrosine kinase inhibitor(EGFR-TKI) gefitinib on cell proliferation, clonogenic capacity and apoptosis in the drug-resistant lung cancer cell line NCI-H1975, and further investigate the molecular mechanisms involved.METHODS: NCI-H1975 cells were treated with curcumin and gefitinib alone or in combination, and cell proliferation, clonogenic capacity and apoptosis were examined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay, clone forming experiments, and flow cytometry, respectively, while p38, extracellular regulated protein kinase(ERK)1/2, and protein kinase B(AKT)phosphorylation were examined using Western blotting.RESULTS: Compared with the effects of either agent alone, the combination of curcumin and gefitinib had a stronger suppressive effect on proliferation and the clonogenic capacity(P < 0.05), and showed an increased ability to promote apoptosis(P < 0.05) and reduce p38, ERK1/2, and AKT phosphorylation(P < 0.05).CONCLUSION: Co-treatment of curcumin and gefitinib significantly improves the ability of gefitinib to inhibit cell proliferation, suppress the clonogenic capacity and enhance apoptosis in NCI-H1975 cells,and these effects are possibly mediated via a decrease in phosphorylation of proteins in downstream pathways of the epidermal growth factor receptor.

Correlativity study between expression of DNA double-strand break repair protein and radiosensitivity of tumor cells

DNA double-strand break(DSB)is generally regarded as the most lethal of all DNA lesions after radiation.Ku80,DNA-PK catalytic subunit(DNA-PKcs)and ataxia telangiectasia mutated(ATM)proteins are major DSB repair proteins.In this study,survival fraction at 2Gy(SF2)values of eight human tumor cell lines(including four human cervical carcinoma cell lines HeLa,SiHa,C33A,Caski,three human breast carcinoma cell lines MCF-7,MDA-MB-231,MDA-MB-453,and one human lung carcinoma cell line A549)were acquired by clone formation assay,and western blot was applied to detect the expressions of Ku80,DNA-PKcs and ATM protein.The correlativity of protein expression with SF2 value was analyzed by Pearson linear correlation analysis.We found that the expression of the same protein in different cell lines and the expression of three proteins in the same cell line had a significant difference.The SF2 values were also different in eight tumor cell lines and there was a positive correlativity between the expression of DNA-PKcs and SF2(r=0.723,P=0.043),but Ku80 and ATM expression had no correlation with SF2(P>0.05).Thesefindings suggest that the expression level of DNA-PKcs protein can be an indicator for predicting the radiosensitivity of tumor cells.

Tumor blood vessels formation in osteosarcoma:vasculogenesis mimicry

BACKGROUND: Osteosarcoma is characterized by high neovascularization and a high propensity for metastasis through bloodstream. This study was to examine whether there is evidence for vasculogenic mimicry in osteosarcoma and to illustrate mechanism of tumor blood vessels formation in osteosarcoma. METHODS: Osteosarcoma cell lines (U-2OS) were tested for their ability to form tubular networks in three-dimensional culture containing type I collagen. The structures of the tubular networks were observed with phase contrast microscope and transmission electron microscope (TEM). Morphometric studies using hematoxylin and eosin (HE) stain and CD31 immunohistochemical stain to show tumor-lined channels in human osteosarcoma were also performed. RESULTS: Observation with light microscope and TEM showed that highly aggressive osteosarcoma cell lines (U-2OS) formed networks containing channels when grown in three-dimensional culture containing type I collagen, in the absence of endothelial cells or fibroblasts. Morphometric observation using HE stain and CD31 immunohistochemical stain showed that tumor cell-lined channels were also detected in vivo in osteosarcoma; by comparison, all vascular areas in the pedicle of osteochondroma or outside osteochondroma were endothelial-lined. CONCLUSION: These observations strongly suggest that aggressive osteosarcoma cells may generate vascular channels that facilitate tumor perfusion independent of tumor angiogenesis and have the ability of vasculogenic mimicry.