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Although chemotherapy succeeds in reducing tumor burden, the efficacy is limited due to acquired drug resistance and often irreparable side effects. Studies show that antioxidants may influence the response to chemotherapy and its side effects, although their use remains controversial. The evidence shows that some chemo-drugs induce oxidative stress and lead to normal tissue apoptosis and the entry of cancer cells to a dormant G0 state. Through the suppression of oxidative stress, antioxidants could protect normal cells and bring the tumor out of dormancy so as to expose it to chemotherapies. This review is focused on the redox biology of cancer/normal cells and association of reactive oxygen species with drug resistance, cancer dormancy, and side effects. To this end, evidence from cellular, animal, and clinical studies is provided to better understand the conundrum of dietary antioxidants in cancer chemotherapy. [ABSTRACT FROM AUTHOR]

Using a recombinant phage containing the mouse β-globin gene with λgtWES bacteriophage DNA, transcription initiation sites for Escherichia coli RNA polymerase and calf thymus RNA polymerase B were mapped at the 5′ and 3′ ends of the mouse β-globin gene. The bacterial enzyme was capable of initiating RNA synthesis at the 3′ end site located at about 700 residues from the 3′ end of the β-globin restriction enzyme map. Initiation at this site was more efficient than initiation at the known early λ promotors (PL, PR) (Calf thymus RNA polymerase B initiated transcription at the same sites as the bacterial enzyme but in this case maximum efficiency was at the 5′ end site as compared to the 3′ end site. Initiation of transcription occurs in the region of the d(T-A-T-A-A) sequence. Initiation efficiency at the 5′ end site, as probed by the maximum rate of transcription, was shown to depend partly upon the presence of the adjacent sequences upstream and downstream of the 5′ initiation site [ABSTRACT FROM AUTHOR]

Purified non-histone proteins from mouse mammary cells bind specifically to homologous DNA or chromatin. Complexes of non-histone protein with DNA or chromatin, isolated on agarose columns, were transcribed with both Escherichia coli RNA polymerase and RNA polymerase B from calf thymus. The fact that complexing of DNA with non-histone proteins increases transcription by E. coli RNA polymerase but not by RNA polymerase B suggests different mechanisms of transcription by these two enzymes. Similar experiments with mouse and Drosophila chromatin indicate that non-histone proteins specifically stimulate the transcription of mouse chromatin by RNA polymerase B. Non-histone proteins stimulate the transcription of mouse mammary tumor virus sequences in chromatin by RNA polymerase B but not by E. coli RNA polymerase. We conclude that those non-histone proteins bound specifically to chromatin are able to activate the transcription of specific genes by eukaryotic RNA polymerase. [ABSTRACT FROM AUTHOR]

The specificity of the binding of purified non-histone proteins to DNA has been investigated through two types of experiments. Using a nitrocellulose filter assay at a low protein/DNA ratio, the binding of mouse non-histone proteins to mouse DNA was twice as great as the binding of mouse non histone protein to Drosophila DNA. The reverse experiment using Drosophila non-histone protein confirmed the interpretation that some protein · DNA complexes were specific. Protein · DNA complexes isolated by gel filtration chromatography indicated that 20% or 10% of the non-histone protein was bound to homologous or heterologous DNA respectively. Purified non-histone proteins bound with lower efficiency (15%) than unpurified but with higher specificity to soluble chromatin than to naked DNA. This binding did not result from an exchange between chromatin non-histone proteins and purified non-histone proteins added in excess. DNA-bound and chromatin-bound proteins were analysed on polyacrylamide gels. Whereas no major qualitative differences were observed with DNA-bound proteins, some proteins bound to homologous mouse chromatin were different from those bound to heterologous Drosophila chromatin. These results suggest a possible role of DNA-bound non-histone proteins in the regulation of gene expression. [ABSTRACT FROM AUTHOR]

Accurate initiation of transcription in vitro requires, in addition to RNA polymerase II, factors present in soluble extracts of cultured cells. We have developed transcription system in vitro, which permits us to visualize the transcription-initiation complexes on a mouse β globin restricted fragment from a recombinant β globin bacteriophage DNA. Using the γ fragments as internal controls this system has allowed us to assess the specificity of transcription with RNA polymerase II. Comparing extracts from cells and tissues expressing the globin genes (Friend cells, spleen and blood from phenylhydrazine-induced anemic mice) with those which do not (thymus, liver, PCC3 cells), we observed that specific initiation of transcription on the β globin gene occurs only with solubic extracts from erythroid tissues. This tissue-specific transcription is partially sensitive to α-amanitin and occurs at the 5′ end of the globin gene. [ABSTRACT FROM AUTHOR]

Background/aim: Both the sulfated and non-sulfated derivatives (e.g. carboxymethyl benzylamide dextrans) of heparan sulfate were reported to have anticancer activity. On this basis, we introduced sulfates and phenyls in carboxymethyl benzylamide dextrans into chitosan, which is easily modified by different functional groups in any given position and then evaluated anticancer activity in breast cancer cells., Materials and Methods: Chitosan derivatives were synthesized by introducing sulfate and phenyl groups into chitosan. Cell proliferation and apoptosis were assessed by (3)H-thymidine incorporation and fluorescence activated cell sorter analysis. Activation of Ras/MAPK signaling pathway downstream of fibroblast growth factor-2 (FGF-2) was analyzed by Western blot., Results: The sulfated chitosan (SCS) and the sulfated benzaldehyde chitosan (SBCS) significantly inhibited cell proliferation, induced apoptosis and blocked the FGF-2-induced phosphorylation of ERK in MCF-7 cells, SBCS had better inhibitory effects and a lower IC(50) compared to SCS., Conclusion: The sulfated and benzaldehyde chitosans seem to be good potential compounds for anticancer drug design.

Mutual interactions between human breast cancer cells and endothelial cells were studied in a model mimicking tumor cell intravasation. MDA-MB-231 tumor cells and human umbilical vein endothelial cells (HUVEC) were cocultured on opposite sides of a Transwell filter allowing tumor cell contacts with the basement membrane of the HUVEC forming endothelium and tumor cell transendothelial migration. Confocal microscopy analysis showed that transmigrating MDA-MB-231 cells lay under the HUVEC, thereby inducing HUVEC detachment and tumor cell-HUVEC contact-dependent apoptosis. GM6001 a matrix metalloproteinase (MMP) inhibitor inhibited almost completely, the MDA-MB-231 cell transendothelial migration and the anoikis process. In this intravasation model, a tumor cell invasive mechanism was demonstrated (i) induction of extensive endothelial anoikis induced by degradation of the extracellular matrix (ECM) components, (ii) activation of pro-matrix metalloproteinase (MMP)-2 into MMP-2 by the MT1-MMP-TIMP (tissue inhibitor metalloproteinase) 2-pro-MMP-2 membrane complex and (iii) attraction and migration of metastatic cell through apoptotic endothelium. These interactions could partly explain the necrosis-angiogenesis relationship in tumor angiogenesis.

A monomeric RGD-disintegrin was recently identified from a cDNA library from the venom gland of Bothrops alternatus. The corresponding 12 kDa-recombinant protein, DisBa-01, specifically interacted with alpha(v)beta3 integrin and displayed potent anti-metastatic and anti-angiogenic properties. Here, the interaction of DisBa-01 with platelet alphaIIb beta3 integrin and its effects on hemostasis and thrombosis were investigated. DisBa-01 bound to Chinese Hamster Ovary (CHO) cells expressing beta3 or alphaIIb beta3 and promoted their adhesion and the adhesion of resting platelets onto glass coverslips. The disintegrin inhibited the binding of FITC-fibrinogen and FITC-PAC-1 to ADP-stimulated platelets and inhibited ADP-, TRAP- and collagen-induced aggregation of murine, rabbit or human platelets. In a flow chamber assay, DisBa-01 inhibited and reverted platelet adhesion to immobilized fibrinogen. DisBa-01 inhibited the phosphorylation of FAK following platelet activation. The intravenous injection of DisBa-01 in C57Bl6/j mice, prolonged tail bleeding time as well as thrombotic occlusion time in mesenteric venules and arterioles following vessel injury with FeCl3. In conclusion, DisBa-01 antagonizes the platelet alphaIIb beta3 integrin and potently inhibits thrombosis.

Background: Multiform glioblastomas represent the most aggressive brain tumors. Here, the cooperative effects of sodium phenylacetate (NaPa) and/or tamoxifen (TAM) on CNS1 and 9L glioblastoma cell lines in vitro and in an experimental animal tumor model were investigated., Materials and Methods: The drug effects on cell cycle and apoptosis were investigated by flow cytometry. CNS1 cells were implanted subcutaneously in nude mice to form tumors which were then treated with NaPa, TAM or NaPa/TAM., Results: A significant inhibitory effect of NaPa on the two glioma cell lines (LD50 of 10 mM) was observed. 10(-5) M of TAM inhibited approximately 35% of 9L cell growth, and 90% of CNS1 cell growth. When a combination of both drugs included 10(-9) M of TAM, inhibition of about 50% of 9L cell growth and 75% of CNS1 cell growth occurred. The NaPa/TAM combined treatment increased the number of G0/G1 arrested cells and apoptotic cells as compared to treatments with NaPa or TAM alone. Inhibition of CNS1 tumor growth were observed after a two week treatment with NaPa (32 mg/kg/day) or TAM (6 mg/kg/day)., Conclusion: These results showed a synergistic effect between these two drugs on tumor cell proliferation, caused by cell cycle arrest in the G0/G1 phase and by induction of apoptosis.

Carboxy methyl dextran benzylamide jorge (CMDBJ) is a derivatized dextran prepared from native dextran after random carboxymethylation of hydroxyl groups on D-glucose units (CM) and consecutive conversion of some carboxylate groups to benzylamide structures (B). This polymer exhibits an inhibitory action upon the proliferation of 1205 L-U human melanoma cells. At low concentrations, this compound exerts a cytostatic effect whereas, at higher concentrations, a cytotoxicity appears within 24 hours of treatment. The 1205 L-U cell line forms subcutaneous angiogenic tumors in athymic mice and, after several weeks, spontaneously forms micrometastasis in the lungs. We demonstrated that the CMDBJ treatment of animals not only reduces the rapid growth of primary tumors but also induces tumor regression and tumor necrosis. Moreover, CMDBJ treatment blocks the appearance of lung metastasis. Pleiotrophin (PTN), heparin-binding angiogenic growth factor, is secreted by 1205 L-U cells and breast tumor MDA-MB 231 cells. CMDBJ, as an inhibitor of heparin-binding growth factor activities, suppresses the mitogenic activity of conditioned media from 1205 L-U and MDA-MB 231 on endothelial HUVEC cells. We conclude that CMDBJ can inhibit the in vitro cell proliferation of 1205 L-U cells and 1205 L-U tumor development in athymic mice and that PTN secreted by these cells could be involved in this inhibition.