Consequences of combining siRNA-mediated DNA methyltransferase 1 depletion with 5-aza-2'-deoxycytidine in human leukemic KG1 cells.

5-azacytidine and 5-aza-2'-deoxycytidine are clinically used to treat patients with blood neoplasia. Their antileukemic property is mediated by the trapping and the subsequent degradation of a family of proteins, the DNA methyltransferases (DNMT1, DNMT3A, and DNMT3B) leading to DNA demethylation, tumor suppressor gene re-expression and DNA damage. Here we studied the respective role of each DNMT in the human leukemia KG1 cell line using a RNA interference approach.

Design, synthesis and biological evaluation of 4-amino-N- (4-aminophenyl)benzamide analogues of quinoline-based SGI-1027 as inhibitors of DNA methylation.

Quinoline derivative SGI-1027 (N-(4-(2-amino-6-methylpyrimidin-4-ylamino)phenyl)-4-(quinolin-4-ylamino)benzamide) was first described in 2009 as a potent inhibitor of DNA methyltransferase (DNMT) 1, 3A and 3B. Based on molecular modeling studies, performed using the crystal structure of Haemophilus haemolyticus cytosine-5 DNA methyltransferase (MHhaI C5 DNMT), which suggested that the quinoline and the aminopyridimine moieties of SGI-1027 are important for interaction with the substrates and protein, we designed and synthesized 25 derivatives. Among them, four compounds—namely the derivatives 12, 16, 31 and 32—exhibited activities comparable to that of the parent compound.

Semisynthetic neoboutomellerone derivatives as ubiquitin-proteasome pathway inhibitors.

The interesting pharmacological properties of neoboutomellerones 1 and 2 were the basis for the assembly of a small library of analogues consisting of natural products isolated from the plant Neoboutonia melleri and of semisynthetic derivatives. As the two enone systems (C23-C24a and C1-C3) and the two hydroxyls groups (C22 and C26) of neoboutomellerones are required for activity, modifications were focused on these functional groups. Biological evaluation by using a cellular assay for proteasome activity provided clues regarding the mechanism of action of these natural products and synthetic derivatives.

Cytotoxicity and cell death mechanisms induced by the polyamine-vectorized anti-cancer drug F14512 targeting topoisomerase II.

The polyamines transport system (PTS) is usually enhanced in cancer cells and can be exploited to deliver anticancer drugs. The spermine-conjugated epipodophyllotoxin derivative F14512 is a topoisomerase II poison that exploits the PTS to target preferentially tumor cells. F14512 has been characterized as a potent anticancer drug candidate and is currently in phase 1 clinical trials.

An integrated Drosophila model system reveals unique properties for F14512, a novel polyamine-containing anticancer drug that targets topoisomerase II.

F14512 is a novel anti-tumor molecule based on an epipodophyllotoxin core coupled to a cancer-cell vectoring spermine moiety. This polyamine linkage is assumed to ensure the preferential uptake of F14512 by cancer cells, strong interaction with DNA and potent inhibition of topoisomerase II (Topo II). The antitumor activity of F14512 in human tumor models is significantly higher than that of other epipodophyllotoxins in spite of a lower induction of DNA breakage.

Four new carvotanacetone derivatives from Sphaeranthus ukambensis, inhibitors of the ubiquitin-proteasome pathway.

Six carvotanacetone derivatives (1- 6), amongst which four new compounds (1- 4), were isolated from the aerial parts of Sphaeranthus ukambensis Vatke & O. Hoffm. The structures of the molecules were elucidated by complementary spectroscopic methods, and their biological properties were investigated using human DLD-1 colon cancer cells engineered to stably express a 4 ubiquitin-luciferase (4 Ub-Luc) reporter protein.

Triptolide is an inhibitor of RNA polymerase I and II-dependent transcription leading predominantly to down-regulation of short-lived mRNA.

Triptolide, a natural product extracted from the Chinese plant Tripterygium wilfordii, possesses antitumor properties. Despite numerous reports showing the proapoptotic capacity and the inhibition of NF-kappaB-mediated transcription by triptolide, the identity of its cellular target is still unknown. To clarify its mechanism of action, we further investigated the effect of triptolide on RNA synthesis in the human non-small cell lung cancer cell line A549.

Synthesis of conjugated spermine derivatives with 7-nitrobenzoxadiazole (NBD), rhodamine and bodipy as new fluorescent probes for the polyamine transport system.

The synthesis of a series of conjugated spermine derivatives with benzoxadiazole, phenylxanthene or bodipy fluorophores is described. These fluorescent probes were used to identify the activity of the polyamine transport system (PTS). N(1)-Methylspermine NBD conjugate 5 proved to have the optimal fluorescence characteristics and was used to show a selectivity for PTS-proficient CHO versus PTS-deficient CHO-MG cells.

Antitumor activity of pyridoisoquinoline derivatives F91873 and F91874, novel multikinase inhibitors with activity against the anaplastic lymphoma kinase.

The anaplastic lymphoma kinase (ALK) is a validated target for the therapy of different malignancies. Aberrant expression of constitutively active ALK chimeric proteins has been implicated in the pathogenesis of anaplastic large-cell lymphoma (ALCL) and has been detected in other cancers such as inflammatory myofibroblastic tumors, diffuse large B-cell lymphomas, certain non-small-cell lung cancers, rhabdomyosarcomas, neuroblastomas and glioblastomas. In the course of a screening program aimed at identifying kinase inhibitors with novel scaffolds, the two pyridoisoquinoline derivatives F91873 and F91874, were identified as multikinase inhibitors with activity against ALK in a biochemical screen.

F14512, a potent antitumor agent targeting topoisomerase II vectored into cancer cells via the polyamine transport system.

The polyamine transport system (PTS) is an energy-dependent machinery frequently overactivated in cancer cells with a high demand for polyamines. We have exploited the PTS to selectively deliver a polyamine-containing drug to cancer cells. F14512 combines an epipodophyllotoxin core-targeting topoisomerase II with a spermine moiety introduced as a cell delivery vector.

Physalin B, a novel inhibitor of the ubiquitin-proteasome pathway, triggers NOXA-associated apoptosis.

The ubiquitin-proteasome pathway plays a critical role in the degradation of proteins involved in tumor growth and has therefore become a target for cancer therapy. In order to discover novel inhibitors of this pathway, a cellular assay reporter of proteasome activity was established. Human DLD-1 colon cancer cells were engineered to express a 4 ubiquitin-luciferase (DLD-1 4Ub-Luc) reporter protein, rapidly degraded via the ubiquitin-proteasome pathway and designed DLD-1 4Ub-Luc cells.

Synthesis and biological evaluation of bengacarboline derivatives.

Novel derivatives of the marine alkaloid bengacarboline have been synthesized. The seco derivatives 11 and 12 were evaluated for topoisomerase inhibition, DNA damages, cytotoxicity and cell cycle perturbation. The two synthetic analogs are more potent cytotoxic agents than bengacarboline and they both induce an accumulation of cells in the S phase of DNA synthesis.

Poly(ADP-ribose) polymerase-1 is a negative regulator of HIV-1 transcription through competitive binding to TAR RNA with Tat.positive transcription elongation factor b (p-TEFb) complex.

Human immunodeficiency virus, type 1 (HIV-1) transcription is regulated by a virus-encoded protein, Tat, which forms a complex with a host cellular factor, positive transcription elongation factor b (P-TEFb). When this complex binds to TAR RNA synthesized from the HIV-1 long terminal repeat promoter element, transcription is trans-activated. In this study we showed that, in host cells, HIV-1 transcription is negatively regulated by competition of poly(ADP-ribose) polymerase-1 (PARP-1) with Tat.

Double-strand DNA break formation mediated by flap endonuclease-1.

Double-strand DNA breaks are the most lethal type of DNA damage induced by ionizing radiations. Previously, we reported that double-strand DNA breaks can be enzymatically produced from two DNA damages located on opposite DNA strands 18 or 30 base pairs apart in a cell-free double-strand DNA break formation assay (Vispé, S., and Satoh, M.