Background and Purpose In polychemotherapy protocols, that is for treatment of neuroblastoma and Ewing sarcoma, Vinca alkaloids and cell cycle-arresting drugs are usually administered on the same day. Here we studied whether this combination enables the optimal antitumour effects of Vinca alkaloids to be manifested. Experimental Approach Vinca alkaloids were tested in a preclinical mouse model in vivo and in vitro in combination with cell cycle-arresting drugs. Signalling pathways were characterized using RNA interference. Key Results In vitro, knockdown of cyclins significantly inhibited vincristine-induced cell death indicating, in accordance with previous findings, Vinca alkaloids require active cell cycling and M-phase transition for induction of cell death. In contrast, anthracyclines, irradiation and dexamethasone arrested the cell cycle and acted like cytostatic drugs. The combination of Vinca alkaloids with cytostatic therapeutics resulted in diminished cell death in 31 of 36 (86%) tumour cell lines. In a preclinical tumour model, anthracyclines significantly inhibited the antitumour effect of Vinca alkaloids in vivo. Antitumour effects of Vinca alkaloids in the presence of cytostatic drugs were restored by caffeine, which maintained active cell cycling, or by knockdown of p53, which prevented drug-induced cell cycle arrest. Therapeutically most important, optimal antitumour effects were obtained in vivo upon separating the application of Vinca alkaloids from cytostatic therapeutics. Conclusion and Implications Clinical trials are required to prove whether Vinca alkaloids act more efficiently in cancer patients if they are applied uncoupled from cytostatic therapies. On a conceptual level, our data suggest the implementation of polychemotherapy protocols based on molecular mechanisms of drugdrug interactions. Linked Article This article is commented on by Solary, pp 15551557 of this issue. To view this commentary visit http://dx.doi.org/10.1111/bph.12101

BACKGROUND:Glucocorticoids are widely used for cancer patients, although they can reduce the efficacy of anticancer treatment.MATERIALS AND METHODS:We characterized non-apoptotic actions of glucocorticoids on tumor cell lines, primary tumor cells and an in vivo model, together with molecular signaling studies.RESULTS:Glucocorticoids enhanced cell proliferation in 9/17 cell lines and significantly promoted tumor cell proliferation in a pre-clinical mouse model of lung carcinoma. 65/139 primary acute childhood leukemia samples were glucocorticoid-resistant. Both dexamethasone and prednisolone increased in vitro survival in 21/65 samples from glucocorticoid-resistant primary leukemias, revealing a completely new action of glucocorticoids. Dexamethasone-induced proliferation was mediated by glucocorticoid receptor and activated the proliferation signaling pathways of protein kinase B/AKT and p38 mitogen-activated protein kinase.CONCLUSION:Our data suggest that restriction of the use of glucocorticoids during anticancer treatment might improve the outcome of patients with solid tumors.

Glucocorticoid hormones (GCs) are able to modulate leukocyte activity. We studied the effect of dexamethasone (DEX) on the expression of CD2, an adhesion molecule involved in T-lymphocyte homing and activation. Results of flow cytometry analysis and immunoprecipitation with anti-CD2 monoclonal antibodies (mAbs) indicated that in vitro treatment with DEX augments CD2 expression in transformed T-cell lines. This effect correlated with a rapid increase in the mRNA and was inhibited by actinomycin-D (AD). The DEX-induced CD2 augmentation was transient, peaked at days 1–2 and returned to the levels of untreated controls at days 3–4. It was a dose-dependent phenomenon, mediated by the GC receptor (GCR), because it was inhibited by the GCR antagonist RU486, and was not induced by other steroids such as testosterone and progesterone. This CD2 modulation could presumably contribute to GC-induced effects on T-cell activity.

Background: Expression of early genes and episomal DNA replication of human papilloma virus (HPV) is dependent from an active AP1 complex. Activation of AP1 was shown to be precluded by inhibition of phosphatidylcholine specific phospholipase C (PC-PLC). We studied the effect of the PC-PLC inhibitor LMV-601 on HPV-31 infected 9E cervical epithelial cells (CIN 612 9E). LMV-601 is (-)-exo/exo-O-Tricyclo-[5.2.1.0(2,6)]-dec-9-yl-dithiocarbonate potassium salt. Tricyclo-[5.2.1.0(2,6)]-dec-9-yl-dithiocarbonate potassium salt consists of 8 isomers (4 diastereomers, each having 2 enantiomers) and became known under the code D609, first synthesized in 1984 by Merz and Co in co-operation with the German Cancer Research Centre (DKFZ). The pure (-)-exo/exo isomer was first isolated in 2006 and is developed by Lumavita AG as an antiviral drug. Methods: 9E HPV-31 infected cervical epithelial cells were from L.A. Laimins, Chicago. (a) Short term study: After 72 h treatment, effect on cell growth, HPV-31 specific DNA (Southern Blotting) and RNA (Northern Blotting) was assessed. (b) Long term treatment (9 passages): After each passage, viral RNA and DNA levels, and cell morphology were assessed. Results: (a) Short term study: LMV-601 displayed a dose dependent inhibitory effect on cell growth(IC50 16 !g/mL), HPV-31 specific RNA expression (IC50 10.69 !g/mL) and DNA content (62.5% reduction at the highest dose tested, i.e. 32 !g/mL). (b) Long term treatment: The number of passages required to reduce the amount of HPV-31 specific RNA by 50% (T50RNA) was 2.23 at 3.3 !g/mL LMV-601 and < 1 at 10 !g/mL LMV-601. The corresponding T50DNA values were 3.28 and < 1, respectively. After six passages the growth rate of the cells was reduced and the morphology of the cells changed from the spindle form to a normal phenotype. After passage 9, cells were enlarged, became senescent (identified by expression of the senescence marker beta-gal), and ceased to grow. When human, non-HPV immortalized HaCat keratinocytes were treated with the same concentrations of LMV-601, neither cumulative inhibition of growth rate nor induction of senescence could be observed. Conclusion: LMV-601 inhibits HPV-31 specific RNA expression and DNA replication. Furthermore, these results support the hypothesis that chronic treatment with LMV-601 "cures" pre-cancerous 9E keratinocytes by elimination of HPV genomes. Abstracts for SupplementInternational Journal of Infectious DiseasesVol. 14Preview Full-Text PDF Open Archive

The human selenoprotein thioredoxin reductase is involved in antioxidant defense and DNA synthesis. As increased thioredoxin reductase levels are associated with drug sensitivity to cisplatin and drug resistance in tumor cells, this enzyme represents a promising target for the development of cytostatic agents. To optimize the potential of the widely used cisplatin to inhibit the human thioredoxin reductase and therefore to overcome cisplatin resistance, we developed and synthesized four cis-diamminedichloroplatinum complexes of the lead 5-nitro-2-furan-carbohydrazide 8 selected from high-throughput screening. Detailed kinetics revealed that the isolated fragments, 5-nitro-2-furancarbohydrazide and cisplatin itself, bind with micromolar affinities at two different subsites of the human enzyme. By tethering both fragments four nitrofuran-based cis-diamminedichloroplatinum complexes 13a-c and 20 were synthesized and identified as biligand irreversible inhibitors of the human enzyme with nanomolar affinities. Studies with mutant enzymes clearly demonstrate the penultimate selenocysteine residue as the prime target of the synthesized cis-diamminedichloroplatinum complexes.

To establish structure-activity relationships, derivatives of bis(O-alkyldithiocarbonato)platinum(II) complexes were analyzed. Eighteen bis(O-alkyldithiocarbonato) metal complexes were synthesized, and their cytotoxic activity on two human cancer cell lines was compared with the corresponding platinum bis(O-alkyldithiocarbonato) complexes and cisplatin. Complexes were synthesized with palladium, gold, nickel, copper, rhodium, and bismuth. Palladium and bismuth complexes were found to display significant cytotoxic activity. Palladium complexes were most active with up to 10-fold lower IC50 values as compared with the corresponding platinum complexes. The other complexes were only poorly active. Palladium, bismuth, and nickel complexes were more active at pH 6.8 than at pH 7.4. This difference in activity was most pronounced with palladium complexes. A pH of 6.8 and lower has been frequently found in solid tumors. Drugs with such pH dependent activity are supposed to have an improved therapeutic index as compared to drugs that are active irrespective of pH.

Stimulation of macrophages by lipopolysaccharide (LPS) leads to the synthesis of proinflammatory cytokines and nitric oxide (NO) and, as a consequence, to endotoxic shock. We provide evidence that LPS stimulates the activity of a membrane-associated neutral sphingomyelinase (nSMase) and that this activity is mandatory for the liberation of nuclear factor-kappa B (NF kappa B) and the induction of inducible NO-synthase (iNOS). With the aid of a newly developed, selective inhibitor of nSMase, C11AG, we could distinguish between nSMase-dependent and -independent LPS-induced signals. C11AG blocked LPS-stimulated sphingomyelin degradation and NF kappa B activation without interfering with p42 tyrosine phosphorylation. Concomitantly, the expression of iNOS was found to be reduced both in mononuclear cells and in murine endotoxemia. Therefore, specific inhibitors of nSMase may define a new class of antiinflammatory substances.

Platinum complexes are essential tools for cancer treatment despite their toxic side effects. Here we describe a new platinum complex with sulphurs as complexing atoms (thioplatin). Purpose: To demonstrate that the antitumoral activity of a new sulphur-containing platinum compound (thioplatin) depends on a slightly acidic pH. Methods: Platinum uptake by tumour cells and interaction with DNA was determined at slightly acidic or alkaline pH. To demonstrate low in vivo toxicity the effects of thioplatin on body weight, blood urea nitrogen, white blood cell count and the histopathological appearance of small intestines and kidneys were evaluated at doses that displayed antitumoral effects against human small-cell lung cancer and human colorectal cancer xenotransplants in nude mice. Results: The slightly acidic pH optimum of thioplatin was proven by the altered electrophoretic mobility of plasmid DNA, quantitation of the platinum content in the DNA of tumour cells and cytotoxicity studies. Thioplatin displayed antitumoral activity without severe side effects such as weight loss, renal ischaemia, destruction of villi in the small intestine or leukopenia as observed at comparable doses of cisplatin. Furthermore, probably due to its lipophilic nature, thioplatin was taken up readily even by cisplatin-resistant cells. In vivo studies with human tumour xenografts in nude mice showed a therapeutic index of thioplatin five to ten times higher than that of cisplatin.

We synthesized a series of new guanidinium derivatives and studied the inhibitory activity on both neutral sphingomyelinase and herpes simplex virus-1 (HSV-1) replication. The lipophilic quality of the molecules was found to be correlated with the inhibitory potential of the compounds. Undecylidene-aminoguanidine was superior to derivatives with 10, 8 or 6 carbon atoms whereas propylidene-aminoguanidine was completely inactive. Decylidene-aminoguanidine was the most active derivative, with 10 carbon atoms. Various cyclic saturated isomers were inferior to the linear molecule. Aromatic cyclic residues were superior to saturated cyclic residues. The most active compound was a derivative containing 11 carbon atoms, undecylidene-aminoguanidine (C11AG), which inhibited the replication of HSV-1 by 50% at a concentration of 2.6 microM while cytotoxic adverse effects were only observed at a concentration of 31 microM. Expression of immediate early gene ICP-4 and concomitantly of HSV-1 specific DNA replication was found to be a target of C11AG. This result suggests that C11AG interferes with cellular signal transduction mechanisms that regulate expression of HSV-1 immediate early genes. C11AG was shown to inhibit neutral sphingomyelinase without affecting phospholipase A2, phosphatidylcholine-specific phospholipase C and phospholipase D.