Radiosensitizing and toxic effect of metronidazole and its ortho-isomer 1-(2-hydroxyethyl)-2-methyl-4-nitroimidazole on Escherichia coli B/r cells

A study was made of the effect of metronidazole and isometronidazole on the survival rate of irradiated and nonirradiated E. coli B/r cells. These substances had similar radiosensitizing activity with regard to anoxic cells and did not sensitize cells irradiated in the air. At the same time, isometronidazole was found to be less toxic than metronidazole.     

Effect of hypoxic cell sensitizer metronidazole on the radiation reaction of clonogenic cells from solid tumors

The clonogenic capacity of cells from peripheral and central zones of solid NKLy tumors of mice treated with metronidazole, a sensitizer of hypoxic cells, and with a mixture of metronidazole and radiation was studied by cloning in diffusion chambers. The cytotoxic effect of metronidazole was only noted during the prolonged interaction with cells under acute hypoxia that was observed in central tumor zones. Metronidazole increased by more than two times the radiosensitivity of cells from the central zones of the tumor and did not influence the radiation response of cells from the peripheral zones. Metronidazole was shown to inhibit the repair of potentially lethal radiation damages.     

Anticancer potential of 3-(arylideneamino)-2-phenylquinazoline-4(3H)-one derivatives

Different quinazoline derivatives have showed wide spectrum of pharmacological activities. Some 3-(arylideneamino)-phenylquinazoline-4(3H)-ones have been reported to possess antimicrobial activity. The present study has been undertaken to evaluate the anticancer effect of these quinazolinone derivatives. The quinazolinone derivatives were synthesized as reported earlier. Compounds containing NO(2), OH, OCH(3), or OH and OCH(3) as substituent(s) on the arylideneamino group were named as P(3a), P(3b), P(3c), and P(3d) respectively. Out of these, P(3a) and P(3d) showed better cytotoxic activity than P(3b) and P(3c) on a panel of six cancer cell lines of different origin, namely, B16F10, MiaPaCa-2, HCT116, HeLa, MCF7, and HepG2, though the effect was higher in B16F10, HCT116, and MCF7 cells. P(3a) and P(3d) induced death of B16F10 and HCT116 cells was associated with characteristic apoptotic changes like cell shrinkage, nuclear condensation, DNA fragmentation, and annexin V binding. Also, cell cycle arrest at G1 phase, alteration of caspase-3, caspase-9, Bcl-2 and PARP levels, loss of mitochondrial membrane potential, and enhanced level of cytosolic cytochrome c were observed in treated B16F10 cells. Treatment with multiple doses of P(3a) significantly increased the survival rate of B16F10 tumor bearing BALB/c mice by suppressing the volume of tumor while decreasing microvascular density and mitotic index of the tumor cells.     

Effect of metronidazole and local irradiation of the tumor on paramagnetic metal complexes of the liver and tumor tissues

A study was made of changes in the intensity of the ESR signals in tissues of sarcoma-37 and liver of mice after radiation of the tumor, administration of metronidazole, and after the combined effect of the two factors. The most pronounced changes in the ESR signals were induced by metronidazole. An appreciable increase in the content of nitrosyl complexes in the tumor was noted after the combined effect of metronidazole and radiation which was indicative of the radiation-induced formation of a large number of metronidazole anion-radicals in the tumor.     

A mathematical model of combined bacillus Calmette-Guerin (BCG) and interleukin (IL)-2 immunotherapy of superficial bladder cancer

We report a mathematical model that describes the growth of superficial bladder cancer and the effect thereupon of immunotherapy based on the administration of Bacillus Calmette-Guerin (BCG) combined or not with interleukin-2 (IL-2). Intravesical instillations of BCG performed after surgical removal of tumors represents an established treatment with approximately 50% success rate. So far, attempts to improve this efficiency have not led to essential changes. However, convincing clinical results have been reported on the combination of IL-2 to BCG, even though this is still not applied in current practice. The present model provides insights into the dynamical outcomes arising in the bladder from the interactions of immune cells with tumor cells in the course of BCG therapy associated or not with IL-2. Specifically, from the simulations performed using seven ordinary and non-linear differential equations we obtained indications on the conditions that would result in successful bladder cancer treatment. We show that immune cells -effector lymphocytes and antigen-presenting cells-expand and reach a sustainable plateau under BCG treatment, which may account for its beneficial effect, resulting from inflammatory “side-effects” which eliminate residual or eventual newly arising tumor cells, providing thus protection from further cancer development. We find, however, that IL-2 does not actually potentiate the effect of BCG as regards tumor cell eradication. Hence, associating both under the conditions simulated should not result in more efficient treatment of bladder cancer patients.     

Synthesis and anti-tumor activities of N'-benzylidene-2-(4-oxothieno[2,3-d]pyrimidin-3(4H)-yl)acetohydrazone derivatives

A compound with a cyclic thienopyrimidine moiety and an aceto-hydrazone moiety in its chemical structure was discovered in a cell-based screening to have noticeable cytotoxicity on several tumor cell lines. A total of 38 derivatives of this compound were synthesized at five steps with high yields. These compounds were tested in standard MTT assays, and several compounds exhibited improved cytotoxic activities. The most potent compounds have IC(50) values of 10-20 μM on A549, HeLa, and MBA-MD-231 tumor cells. Flow cytometry analysis of several active compounds and subsequent examination of caspase activation indicate that they induce caspase-dependent apoptosis in tumor cells. In addition, these compounds do not have obvious effect on a normal cell line HEK-293T, demonstrating the desired selectivity against tumor cells. Results from a fluorescence polarization-based in vitro binding assay indicate that this class of compounds does not significantly interrupt the interactions between Mcl-1 and Bid. Their cytotoxicity is achieved presumably through other mechanisms.     

Effect of (E)-5-(2-bromovinyl)-2'-deoxyuridine on the growth and viral capsid antigen expression of Epstein-Barr virus-associated tumor (B-95-8) cells transplanted to nude mice

When persistently Epstein-Barr virus (EBV)-infected lymphoblastoid (B-95-8) cells were transplanted subcutaneously or intracerebrally to nude mice of either BALB/c or NIH background, tumors developed, and the tumor cells spontaneously expressed viral capsid antigen (VCA). This model was used to evaluate the in vivo anti-EBV activity of (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU), a highly potent and selective antiherpes agent, which was recently shown to inhibit several parameters of EBV infection in vitro. When administered intraperitoneally at 200 mg/kg/day for 4 weeks, or 500 mg/kg/day for 2 weeks, starting immediately after B-95-8 cell inoculation, BVDU effectively reduced tumor growth and VCA expression of either subcutaneously or intracerebrally inoculated B-95-8 cells.     

Frame-shift mutations in NAD(P)H flavin oxidoreductase encoding gene (frxA) from metronidazole resistant Helicobacter pylori ATCC43504 and its involvement in metronidazole resistance

Metronidazole is a critical ingredient for combination therapies of Helicobacter pylori infection, the major cause of peptic ulcer and gastric cancer. It has been recently reported that metronidazole resistance from H. pylori ATCC43504 is caused by the insertion of a mini-IS605 sequence and deletion of sequences in an oxygen insensitive NAD(P)H nitroreductase encoding gene (rdxA). We also found that an additional gene (frxA) encoding NAD(P)H flavin oxidoreductase in the same strain was truncated by frame-shift mutations. To assess whether the frxA truncation is also involved in metronidazole resistance, metronidazole sensitive H. pylori strains ATCC43629 and SS1 were transformed by the truncated frxA gene cloned from strain ATCC43504. All transformed cells grew on agar plates containing 16 microg ml(-1) of metronidazole. The involvement of the frxA gene in metronidazole resistance was also confirmed by insertion inactivation of frxA and/or rdxA genes from strain ATCC43629 and one metronidazole sensitive clinical isolate H. pylori 2600. In addition, the frxA gene cloned from the H. pylori 2600 showed metronidazole nitroreductase activity in Escherichia coli and rendered ordinary metronidazole resistant E. coli to metronidazole sensitive cell. These results indicate that the frxA gene may also be involved in metronidazole resistance among clinical H. pylori isolates.     

Enhancement by metronidazole of the antitumor effect of cyclophosphane

In experiments on mouse tumors (sarcoma-180, Ehrlich ascites tumor and hemoblastosis La) the ability of metronidazole to enhance the antitumor chemotherapeutic action of cyclophosphane was investigated. It was shown that metronidazole (1000 mg/kg) injected 60 min before cyclophosphane administration can elicit an almost two-fold increase in its radioprotective efficiency. The chemosensitizing effect of metronidazole depends on the drug concentration and the tumor type.     

Levosulpiride, (S)-(-)-5-Aminosulfonyl-N-[(1-ethyl-2-pyrrolidinyl) methyl]-2-methoxybenzamide, enhances the transduction efficiency of PEP-1-ribosomal protein S3 in vitro and in vivo

Many proteins with poor transduction efficiency were reported to be delivered to cells by fusion with protein transduction domains (PTDs). In this study, we investigated the effect of levosulpiride on the transduction of PEP-1 ribosomal protein S3 (PEP-1-rpS3), and examined its influence on the stimulation of the therapeutic properties of PEP-1-rpS3. PEP-1-rpS3 transduction into HaCaT human keratinocytes and mouse skin was stimulated by levosulpiride in a manner that did not directly affect the cell viability. Following 12-O-tetradecanoylphorbol- 13-acetate (TPA)-induced inflammation in mice, levosulpiride alone was ineffective in reducing TPA-induced edema and in inhibiting the elevated productions of inflammatory mediators and cytokines, such as cyclooxygenase-2, inducible nitric oxide synthase, interleukin-6 and -1β, and tumor necrosis factor- α. Anti-inflammatory activity by PEP-1-rpS3 + levosulpiride was significantly more potent than by PEP-1-rpS3 alone. These results suggest that levosulpiride may be useful for enhancing the therapeutic effect of PEP-1-rpS3 against various inflammatory diseases. [BMB reports 2011; 44(5): 329-334].     

Synthesis and characterization of a novel Pd(II) complex with the condensation product of 2-(diphenylphosphino)benzaldehyde and ethyl hydrazinoacetate. Cytotoxic activity of the synthesized complex and related Pd(II) and Pt(II) complexes

A new palladium(II) complex 1 of the condensation product of 2-(diphenylphosphino)benzaldehyde (dpba) and ethyl hydrazinoacetate (etha) was synthesized and characterized by elemental analyses, IR, and (1)H NMR spectroscopy. The bound ligand is a bidentate (PN chromophore), the remaining two coordination places being occupied by chloride ions in overall square planar geometry. The cytotoxic activity of the complex 1 and two related Pd(II) and Pt(II) complexes 2 and 3 was tested against a panel of four tumor cell lines. The activity of the complexes was similar to that of cisplatin, the most widely used metal-based antitumor drug. It is important to notice that complexes 2 and 3 were active to cisplatin-resistant U2-OS/Pt cells. Cell cycle alteration investigation, apoptotic assay and gelatin zymography in relation to invasion and metastasis of tumor cells, were performed with all the investigated complexes on Human cervix carcinoma (HeLa) cells. The results suggest that 1 has a similar effect to cisplatin, inducing apoptosis followed by arrest of cells in S phase of cell cycle, while 2 and 3 induce apoptosis without significant perturbations of cell cycle distribution.     

Synthesis and antitumor activity of 1-mesityl-3-(2-naphthoylmethano)-1H-imidazolium bromide

An imidazolium salt, 1-mesityl-3-(2-naphthoylmethano)-1H-imidazolium bromide (MNIB), has been investigated for its antitumor properties. In vitro studies demonstrate that MNIB is active against K562, SMMC-7721, EJ, AGZY, HEP-2, A549, HepG2, and Raji tumor cells, and can induce the G1 phase cell cycle arrest and apoptosis in K562 cells. Moreover, administration of MNIB significantly inhibited tumor growth in human non-small lung tumor (A549) xenografts.     

5-(2-Ethyl-phenyl)-3-(3-methoxy-phenyl)-1H-[1,2,4]triazole (DL-111-IT) and related compounds induce apoptotic patterns in cultures of human tumor cell lines

5-(2-Ethyl-phenyl)-3-(3-methoxy-phenyl)-1H-[1,2,4]triazole (DL-111-IT) and related compounds were extensively studied as anti-gestational agents and some of these molecules were also described as inhibitors of ornithine decarboxylase. Polyamine depletion has been frequently related to the induction of apoptosis and consequently we investigated DL-111-IT and analogs for this effect in myeloid (HL60), neuroblastic (SK-N-MC) and epithelial (BeWo) human tumor cell lines, by means of electron microscopy and DNA electrophoresis. HL60 and SK-N-MC appeared notably sensitive to apoptosis, whereas BeWo responsiveness was variable and frequently associated with necrosis. Our results indicate that the contragestational effect of DL-111-IT and analogs is associated with apoptotic deletion of chorionic tissue and that these molecules, due to their effect on human tumor cell lines, can be considered as antiblastic lead compounds.     

Induction of tumor-inhibitory macrophages with a novel synthetic immunomodulator, 3,6-bis(2-piperidinoethoxy)acridine trihydrochloride (CL 246,738)

3,6-bis(2-piperidinoethoxy)acridine trihydrochloride (CL 246,738) has been investigated for its immunomodulatory effect on murine macrophages. Incubation of macrophages harvested from the peritoneal cavities of normal mice with the compound for 48 to 72 hr rendered these cells inhibitory to the growth of tumor cells in vitro. Activation of tumor-inhibitory macrophages occurred over a range of concentrations (0.025 to 0.1 micrograms/ml) producing no direct inhibitory effects on tumor cells. Treatment of effector cells with carrageenan abrogated the effect, whereas treatment with anti-Thy-1.2 antibody and C did not, suggesting that the primary effectors were macrophages rather than T lymphocytes. These activated macrophages also manifested in vitro tumor cytolysis. In vivo studies indicated that peritoneal macrophages from mice treated with single oral doses of 100 to 400 mg/kg of the compound were also inhibitory to tumor cell growth in vitro. Effector macrophages became demonstrable in mice as early as 1 day after drug administration, reached peak activity at day 12, and disappeared by day 31, indicating a rapid onset but long-persisting effect. The tumor cytostatic activity of these macrophages was augmented by endotoxin at the dose of endotoxin that, in itself, had no effect. The addition of protease inhibitors, N-alpha-p-tosyl-L-lysine chloromethyl ketone and aprotinin, to cultures markedly diminished the cytostatic effect, suggesting that the release of neutral protease(s) could account for the inhibitory effects of the macrophages. On the other hand, hydrogen peroxide and arginase seemed excluded as the mechanism of action because the effect was not sensitive to treatment with catalase and exogenous arginine. The present findings indicate that CL 246,738 is an orally active immunopotentiator capable of inducing tumor-inhibitory macrophages both in vitro and in vivo.     

Investigation of antitumor potential of Ni(II) complexes with tridentate PNO acylhydrazones of 2-(diphenylphosphino)benzaldehyde and monodentate pseudohalides

Square-planar azido Ni(II) complex with condensation product of 2-(diphenylphosphino)benzaldehyde and Girard’s T reagent was synthesized and its crystal structure was determined. Cytotoxic activity of the azido complex and previously synthesized isothiocyanato, cyanato and chlorido Ni(II) complexes with this ligand was examined on six tumor cell lines (HeLa, A549, K562, MDA-MB-453, MDA-MB-361 and LS-174) and two normal cell line (MRC-5 and BEAS-2B). All the investigated nickel(II) complexes were cytotoxic against all tumor cell lines. The newly synthesized azido complex showed selectivity to HeLa and A549 tumor cell lines compared to the normal cells (for A549 IC₅₀ was similar to that of cisplatin). Azido complex interferes with cell cycle phase distribution of A549 and HeLa cells and possesses nuclease activity towards supercoiled DNA. The observed selectivity of the azido complex for some tumor cell lines can be connected with its strong DNA damaging activity.     

N-(2-Amino-phenyl)-4-(heteroarylmethyl)-benzamides as new histone deacetylase inhibitors

A variety of N-(2-amino-phenyl)-4-(heteroarylmethyl)-benzamides were designed and synthesized. These compounds were shown to inhibit recombinant human HDAC1 with IC₅₀ values in the sub-micromolar range. In human cancer cells growing in culture these compounds induced hyperacetylation of histones, induced the expression of the tumor suppressor protein p21^WAF1/Cip1, and inhibited cellular proliferation. Certain compounds of this class also showed in vivo activity in various human tumor xenograft models in mice.     

Cytostatic and cytotoxic effects of (E)-2'-deoxy-2'-(fluoromethylene)-cytidine on a solid tumor and a leukemia cell line

(E)-2'-deoxy-2'-(fluoromethylene)-cytidine (FMdC), a deoxycytidine analog displaying a very high toxicity toward a variety of solid tumor cell lines and xenografts, is activated intracellularly by deoxycytidine kinase (dCK). We have compared cytotoxicity of FMdC towards a human promyeolocytic leukemia line HL-60 and a human colorectal carcinoma line COLO-205. Despite dCK activity being by far the highest in cells of lymphoid origin, the effects of FMdC were detectable at the lowest drug concentration only in a solid tumor cell line, and at higher concentrations they were qualitatively similar in the two tumor lines (increased cell protein content, cell cycle block and apoptosis). Apparently, low dCK activity in solid tumor cells sufficiently activates FMdC to yield cytotoxic effects, while high dCK activity in leukemia cells does not increase its cytotoxicity.     

Discovery of 2-(1H-indol-5-ylamino)-6-(2,4-difluorophenylsulfonyl)-8-methylpyrido[2,3-d]pyrimidin-7(8H)-one (7ao) as a potent selective inhibitor of Polo like kinase 2 (PLK2)

Several families of protein kinases have been shown to play a critical role in the regulation of cell cycle progression, particularly progression through mitosis. These kinase families include the Aurora kinases, the Mps1 gene product and the Polo Like family of protein kinases (PLKs). The PLK family consists of five members and of these, the role of PLK1 in human cancer is well documented. PLK2 (SNK), which is highly homologous to PLK1, has been shown to play a critical role in centriole duplication and is also believed to play a regulatory role in the survival pathway by physically stabilizing the TSC1/2 complex in tumor cells under hypoxic conditions. As a part of our research program, we have developed a library of novel ATP mimetic chemotypes that are cytotoxic against a panel of cancer cell lines. We show that one of these chemotypes, the 6-arylsulfonyl pyridopyrimidinones, induces apoptosis of human tumor cell lines in nanomolar concentrations. The most potent of these compounds, 7ao, was found to be a highly specific inhibitor of PLK2 when profiled against a panel of 288 wild type, 55 mutant and 12 lipid kinases. Here, we describe the synthesis, structure activity relationship, in vitro kinase specificity and biological activity of the lead compound, 7ao.     

Suppression of tumor cell invasiveness by hydrolyzable tannins (plant polyphenols) via the inhibition of matrix metalloproteinase-2/-9 activity

Elevated expression of matrix metalloproteinases (MMPs), especially that of MMP-2 and MMP-9, is associated with increased metastatic potential in many tumor cells. Recently, green tea polyphenol epigallocatechin-3-O-gallate (EGCG) has been shown to inhibit the MMP-2/-9 activity as well as the invasiveness of tumor cells. In this study, we have examined the inhibitory effect of hydrolyzable tannins (plant polyphenols) on the tumor cell invasion. Our results demonstrate that beta-d-glucose whose hydroxy groups are substituted entirely with galloyl group and further some of them are cross-linked to form hexahydroxydiphenoyl group, for example, suppresses the invasiveness of tumor cells much more potently than EGCG via direct inhibition of the MMP-2/-9 activity. Among those examined, 1,2,4-tri-O-galloyl-3,6-hexahydroxydiphenoyl-beta-d-glucose (punicafolin) inhibits the invasion of HT1080 fibrosarcoma cells most potently. These hydrolyzable tannins would provide new leads for the development of potent inhibitors against tumor metastasis.