Chun Liang Chen

Synthesis, cytotoxicity and human telomerase inhibition activities of a series of 1,2-heteroannelated anthraquinones and anthra[1,2-d]imidazole-6,11-dione homologues

A series of 1,2-heteroannelated anthraquinones and anthra[1,2-d]imidazole-6,11-dione tetracyclic analogues with different side chain were prepared using an various synthetic route via acylation, cyclization, condensation, and intramolecular heterocyclization. Tetracyclic system containing alkyl and aryl, aromatic and heterocyclic, linear and cyclic, polar and apolar, and basic and acids residues were incorporated. They were evaluated for their effects on telomerase activity, hTERT expression, cell proliferations, and in vitro cytotoxicity against NCIs 60 cell line human tumor screen. Compounds 4, 11, 12, 14, 15, 16, 17, 19, 20, 23, 25, and 26 were selected by the NCI for one dose screening program and further studies on 4, 23 and 25 where the curves cross these lines represent the interpolated values to cause 50% growth inhibition (GI(50)), total growth inhibition (TGI) and 50% cell killing (LC(50)), respectively. Further studies did not reveal any compound that showed potent and significant on telomerase inhibitory activity and hTERT repressing ability. Comparative testing of these compounds in the NCIs screen revealed varying levels of potency and differential cytotoxicity, apparently related to the unsaturation levels in and substitution patterns on the core ring system. It appeared that addition of a fourth planar aromatic system to a tricyclic chromophore might enhances potent cytotoxic agents, at a level equivalent to a second side chain in one of the tricyclic series. Although the exact mechanism of how this pharmacophore contributes to its activity is still unclear, however, the group in the extended arm of the tetracyclic system might contribute to proper binding to the residues within the grove of G-quadruplex structure.

Structure-based design, synthesis and evaluation of novel anthra[1,2-d]imidazole-6,11-dione derivatives as telomerase inhibitors and potential for cancer polypharmacology

A series of anthra[1,2-d]imidazole-6,11-dione derivatives were synthesized and evaluated for telomerase inhibition, hTERT expression and suppression of cancer cell growth in vitro. All of the compounds tested, except for compounds 4, 7, 16, 24, 27 and 28 were selected by the NCI screening system. Among them, compounds 16, 39, and 40 repressed hTERT expression without greatly affecting cell growth, suggesting for the selectivity toward hTERT expression. Taken together, our findings indicated that the analysis of cytotoxicity and telomerase inhibition might provide information applicable for further developing potential telomerase and polypharmacological targeting strategy.

New approaches of PARP-1 inhibitors in human lung cancer cells and cancer stem-like cells by some selected anthraquinone-derived small molecules.

Poly (ADP-ribose) polymerase-1 (PARP-1) and telomerase, as well as DNA damage response pathways are targets for anticancer drug development, and specific inhibitors are currently under clinical investigation. The purpose of this work is to evaluate anticancer activities of anthraquinone-derived tricyclic and tetracyclic small molecules and their structure-activity relationships with PARP-1 inhibition in non-small cell lung cancer (NSCLC) and NSCLC-overexpressing Oct4 and Nanog clone, which show high-expression of PARP-1 and more resistance to anticancer drug. We applied our library selected compounds to NCIs 60 human cancer cell-lines (NCI-60) in order to generate systematic profiling data. Based on our analysis, it is hypothesized that these drugs might be, directly and indirectly, target components to induce mitochondrial permeability transition and the release of pro-apoptotic factors as potential anti-NSCLC or PARP inhibitor candidates. Altogether, the most active NSC747854 showed its cytotoxicity and dose-dependent PARP inhibitory manner, thus it emerges as a promising structure for anti-cancer therapy with no significant negative influence on normal cells. Our studies present evidence that telomere maintenance should be taken into consideration in efforts not only to overcome drug resistance, but also to optimize the use of telomere-based therapeutics. These findings will be of great value to facilitate structure-based design of selective PARP inhibitors, in general, and telomerase inhibitors, in particular. Together, the data presented here expand our insight into the PARP inhibitors and support the resource-demanding lead optimization of structurally related small molecules for human cancer therapy.

Design, synthesis and evaluation of telomerase inhibitory, hTERT repressing, and anti-proliferation activities of symmetrical 1,8-disubstituted amidoanthraquinones

A series of symmetrical disubstituded 1,8-diamidoanthraquinones were synthesized and evaluated for anti-proliferation, telomerase inhibitory by TRAP assay, and hTERT expression by SEAP assay. All of the compounds tested, except for compounds 3a and 3s were selected by the NCI screening system. In addition, compounds 4e and 4k exhibited inhibitory effects on telomerase activity. Taken together, our findings indicated that the analysis of cytotoxicity and telomerase inhibition might provide information applicable for further developing potential telomerase targeting strategy.

Structure-based design, synthesis and biological evaluation of novel anthra[1,2-d]imidazole-6,11-dione homologues as potential antitumor agents.

By using fragment-based design strategies, a series of 2-thio-substituted anthra[1,2-d]imidazole-6,11-diones were synthesized and evaluated for hTERT repressing activities, cell proliferations, and NCI 60-cell panel assay. Compounds 2, 3, 4, 11, 15 and 35 were selected by the NCI and 3, 4, 11 and 15 represent the GI₅₀, TGI and LC₅₀, respectively. Among them, all were moderate selectivity toward leukemia cancer except for 4 exhibited distinctive selectivity of CNS and renal cancer with 7.403 and 6.475. The overall of test compounds exhibited different cytostatic and cytotoxic activities for further developing potential application as anticancer drugs.

Modified salicylanilide and 3-phenyl-2H-benzo[e][1,3]oxazine-2,4(3H)-dione derivatives as novel inhibitors of osteoclast differentiation and bone resorption.

Inhibition of osteoclast formation is a potential strategy to prevent inflammatory bone resorption and to treat bone diseases. In the present work, the purpose was to discover modified salicylanilides and 3-phenyl-2H-benzo[e][1,3]oxazine-2,4(3H)-dione derivatives as potential antiosteoclastogenic agents. Their inhibitory effects on RANKL-induced osteoclastogenesis from RAW264.7 cells were evaluated by TRAP stain assay. The most potent compounds, 1d and 5d, suppressed RANKL-induced osteoclast formation and TRAP activity dose-dependently. The cytotoxicity assay on RAW264.7 cells suggested that the inhibition of osteoclastic bone resorption by these compounds did not result from their cytotoxicity. Moreover, both compounds downregulated RANKL-induced NF-κB and NFATc1 in the nucleus, suppressed the expression of osteoclastogenesis-related marker genes during osteoclastogenesis, and prevented osteoclastic bone resorption but did not impair osteoblast differentiation in MC3T3-E1. Therefore, these modified salicylanilides and 3-phenyl-2H-benzo[e][1,3]oxazine-2,4(3H)-diones could be potential lead compounds for the development of a new class of antiresorptive agents.

Structure-based hybridization, synthesis and biological evaluation of novel tetracyclic heterocyclic azathioxanthone analogues as potential antitumor agents

A series of tetracyclic heterocyclic azathioxanthones were synthesized and evaluated for cell proliferations, topoisomerase inhibitions, and NCI-60 cell panel assay, respectively. Compounds 5, 7, 8, 16, and 19 were selected for topoisomerase assay after MTT assay. 7 not only showed cytotoxic effect (IC50 = 2.84 ± 0.64 μM) in PC-3 cells but also revealed topoisomerases inhibition with IC50 (10-25 μM) and increased apoptotic cleavage of PARP and caspase 3 activity. The overall of novel azathioxanthones with different cytostatic and cytotoxic activities should be further developed as new potential candidates for anticancer drugs.

Design, synthesis and antiproliferative evaluation of fluorenone analogs with DNA topoisomerase I inhibitory properties.

A series of 2,7-diamidofluorenones were designed, synthesized, and screened by SRB assay. Some synthesized compounds exhibited antitumor activities in submicromolar range. Ten compounds (3a, 3b, 3c, 3g, 3j, 3l, 4a, 4h, 4i, and 4j) were also selected by NCI screening system and 3c (GI50=1.66 μM) appeared to be the most active agent of this series. Furthermore, 3c attenuated topoisomerase I-mediated DNA relaxation at low micromolar concentrations. These results indicated that fluorenones have potential to be further developed into anticancer drugs.

Ring fusion strategy for synthesis and lead optimization of sulfur-substituted anthra[1,2-c[[1,2,5]thiadiazole-6,11-dione derivatives as promising scaffold of antitumor agents

A series of sulfur-substituted anthra[1,2-c][1,2,5]thiadiazole-6,11-diones were synthesized and evaluated using the cell proliferations, apoptosis and NCI-60 cell panel assays. Also, the signaling pathways that account for their activities were investigated. Compounds 2, 3, 4a, 4d, 4f, 4i, 4k, 5b, 5c, 5d, 5f, 5g, 6b, 6c, 6d, 6e, 6g, 7a and 7g were selected by NCI. Among the tested compounds, 6g appeared to be the most active compound of this series that not only induced apoptosis in DU-145 cancer cells but also attenuated the ERK1/2 and p38 signaling pathways. All test compounds exhibited diverse cytostatic and cytotoxic activities that warrant further development as potential anticancer agents.

NSC746364, NSC746365, and NSC746366: The spectra of cytotoxicity and molecular correlates of response to telomerase activity

NSC746364, NSC746365, and NSC746366 are structurally novel 2,7-diamidoanthraquinone derivatives compared with other clinically used anticancer agents and have exhibited a unique multilog differential pattern of activity in our earlier studies. To systematically evaluate their potential anticancer activity, three selected compounds were tested for their cytotoxicity in vitro against 60 human cancer lines in the National Cancer Institutes anticancer drug screen as well as for dose response curves and telomerase activity. Cell growth was analyzed by the MTT assay, with differences between dose–response curves analyzed nonparametrically. Telomerase activity was detected by a modified version of the PCR-based assay and telomere repeat amplification protocol assay. To elucidate the structure–activity relationships and in-vitro anticancer activity, we correlated their activity profile [GI50, total growth inhibition (TGI), and LC50] in the screening system and also their effects on telomerase activity, human telomerase reverse transcriptase expression, cell proliferations, and cytotoxicity. As a result we found that NSC746364, NSC746365, and NSC746366 have potent activity with 50% net growth inhibition conferred by 0.23–16.0 μmol/l (2.08 μmol/l mean); 0.78–15.9 μmol/l (2.57 μmol/l mean); 1.38–63.1 μmol/l (3.89 μmol/l mean), respectively. Sensitive cell lines exhibit TGI and 50% lethality to NSC746364, exhibited an LC50 with as little as 2.82 μmol/l and TGI with as little as 0.95 μmol/l; NSC746365, exhibited an LC50 with as little as 3.30 μmol/l, and TGI with as little as 1.65 μmol/l; NSC746366, exhibited an LC50 with as little as 8.80 μmol/l; and TGI with as little as 4.06 μmol/l, respectively. Results of the study extend the initial in-vitro observation reported in the data above and confirm the importance of anticancer activity and telomerase inhibition. The unique molecular characterization, cytotoxicity, and telomerase activity profiles warrant further investigation and indicate a potential novel mechanism of anticancer action involved.