2-(3-Methoxyphenyl)-5-methyl-1,8-naphthyridin-4(1H)-one (HKL-1) induces G2/M arrest and mitotic catastrophe in human leukemia HL-60 cells

Lin28A/CENPE Promoting the Proliferation and Chemoresistance of Acute Myeloid Leukemia

The prognosis of chemoresistant acute myeloid leukemia (AML) is still poor, mainly owing to the sustained proliferation ability of leukemic cells, while the microtubules have a major role in sustaining the continuity of cell cycle. In the present study, we have identified CENPE, a microtubular kinesin-like motor protein that is highly expressed in the peripheral blood of patients with chemoresistant AML. In our in vitro studies, knockdown of CENPE expression resulted in the suppression of proliferation of myeloid leukemia cells and reversal of cytarabine (Ara-C) chemoresistance. Furthermore, Lin28A, one of the RNA-binding oncogene proteins that increase cell proliferation and invasion and contribute to unfavorable treatment responses in certain malignancies, was found to be remarkably correlated with CENPE expression in chemoresistance AML. Overexpression of LIN28A promoted the proliferation and Ara-C chemoresistance of leukemic cells. RIP assay, RNA pull-down, and dual luciferase reporter analyses indicated that LIN28A bound specifically to the promoter region GGAGA of CENPE. In addition, the impacts of LIN28A on cell growth, apoptosis, cell cycle progression, and Ara-C chemoresistance were reverted by the knockdown of CENPE. Hence, Lin28A/CENPE has enhanced the proliferation and chemoresistance of AML, and therefore, it could be a prospective candidate for AML treatment.

Synthesis and biological evaluation of 3-(1,3,4-oxadiazol-2-yl)-1,8-naphthyridin-4(1H)-ones as cisplatin sensitizers

A series of novel 3-(1,3,4-oxadiazol-2-yl)-1,8-naphthyridin-4(1H)-one derivatives were synthesized and their anti-cancer as well as cisplatin sensitization activities were evaluated. Among them, compounds 6e and 6h exhibited significant cisplatin sensitization activity against HCT116. Hoechst staining and annexin V-FITC/PI dual-labeling studies demonstrated that the combination of 6e/6h and cisplatin can induce tumour cell apoptosis. Western blot showed that the expression of ATR downstream protein, CHK1, decreased in 6e + cisplatin and 6h + cisplatin groups compared with that in the test compound and cisplatin group. Furthermore, docking of 6e/6h into the ATR structure active site revealed that the N1 and N8 atoms in the naphthyridine ring and the hybrid atom in the oxadiazole ring are involved in hydrogen bonding with Val170, Glu168 and Tyr155. Additionally, the naphthyridine ring is also involved in π-π stacking with Trp169. Accordingly, compounds 6e and 6h can be expected to be potential cisplatin sensitizers that can participate in HCT116 cancer therapy.

In vitro anticancer properties and biological evaluation of novel natural alkaloid jerantinine B

Natural products play a pivotal role in medicine especially in the cancer arena. Many drugs that are currently used in cancer chemotherapy originated from or were inspired by nature. Jerantinine B (JB) is one of seven novel Aspidosperma indole alkaloids isolated from the leaf extract of Tabernaemontana corymbosa. Preliminary antiproliferative assays revealed that JB and JB acetate significantly inhibited growth and colony formation, accompanied by time- and dose-dependent apoptosis induction in human cancer cell lines. JB significantly arrested cells at the G2/M cell cycle phase, potently inhibiting tubulin polymerisation. Polo-like kinase 1 (PLK1; an early trigger for the G2/M transition) was also dose-dependently inhibited by JB (IC50 1.5 µM). Furthermore, JB provoked significant increases in reactive oxygen species (ROS). Annexin V+ cell populations, dose-dependent accumulation of cleaved-PARP and caspase 3/7 activation, and reduced Bcl-2 and Mcl-1 expression confirm apoptosis induction. Preclinical in silico biopharmaceutical assessment of JB calculated rapid absorption and bioavailability >70%. Doses of 8-16 mg/kg JB were predicted to maintain unbound plasma concentrations >GI50 values in mice during efficacy studies. These findings advocate continued development of JB as a potential chemotherapeutic agent.

Depletion of Paraspeckle Protein 1 Enhances Methyl Methanesulfonate-Induced Apoptosis through Mitotic Catastrophe

Previously, we have shown that paraspeckle protein 1 (PSPC1), a protein component of paraspeckles that was involved in cisplatin-induced DNA damage response (DDR), probably functions at the G1/S checkpoint. In the current study, we further examined the role of PSPC1 in another DNA-damaging agent, methyl methanesulfonate (MMS)-induced DDR, in particular, focusing on MMS-induced apoptosis in HeLa cells. First, it was found that MMS treatment induced the expression of PSPC1. While MMS treatment alone can induce apoptosis, depletion of PSPC1 expression using siRNA significantly increased the level of apoptosis following MMS exposure. In contrast, overexpressing PSPC1 decreased the number of apoptotic cells. Interestingly, morphological observation revealed that many of the MMS-treated PSPC1-knockdown cells contained two or more nuclei, indicating the occurrence of mitotic catastrophe. Cell cycle analysis further showed that depletion of PSPC1 caused more cells entering the G2/M phase, a prerequisite of mitosis catastrophe. On the other hand, over-expressing PSPC1 led to more cells accumulating in the G1/S phase. Taken together, these observations suggest an important role for PSPC1 in MMS-induced DDR, and in particular, depletion of PSPC1 can enhance MMS-induced apoptosis through mitotic catastrophe.

Immune-modulation and properties of absorption and blood brain barrier permeability of 1,8-naphthyridine derivatives

Considering the high selectivity at the cannabinoid CB2 receptor of recently designed 1,8-naphthyridine derivatives and the protective role of this receptor in neurological disorders, in this study we investigated the immune-modulatory and anti-inflammatory effects of these compounds as well as their potential properties of intestinal absorption and blood-brain barrier (BBB) permeability. We used peripheral blood mononuclear cells (PBMC) known to express the CB2 receptor. We observed that test compounds, CB13, CB82 and CB91 reduced PBMC proliferation. The anti-proliferative effect of CB13 and CB91 was partially mediated by the CB2 receptor. These compounds blocked the cells cycle and CB91 reduced T cell activation. CB82 and CB91 down-regulated the expression of phosphorylated proteins like NF-κB, ERK, Akt and the enzyme Cox-2, CB91 blocked the expression of the CB2 receptor and its inhibitory effect was CB2 receptor mediated. We also investigated CB91 properties of intestinal absorption and BBB permeability in order to suggest its potential efficacy on the infiltrating auto-reactive lymphocytes at the level of the central nervous system. For this purpose, CB91 was tested in drug-permeability assays on Caco-2 cells to evaluate its oral bioavailability and on MDCKII-hMDR1 cells to estimate its BBB permeability. The results indicated that this compound possesses medium level of intestinal absorption and BBB permeability. Our data suggest that CB91, modulating the immune response by CB2 receptor mediated mechanism and showing medium level of intestinal absorption and BBB permeability, might be developed as a potential orally delivered drug and might find potential application in pathologies like multiple sclerosis.

Design and synthesis of 6,7-methylenedioxy-4-substituted phenylquinolin-2(1H)-one derivatives as novel anticancer agents that induce apoptosis with cell cycle arrest at G2/M phase

Novel 6,7-methylenedioxy-4-substituted phenylquinolin-2(1H)-one derivatives 12a-n were designed and prepared through an intramolecular cyclization reaction and evaluated for in vitro anticancer activity. Among the synthesized compounds, 6,7-methylenedioxy-4-(2,4-dimethoxyphenyl)quinolin-2(1H)-one (12e) displayed potent cytotoxicity against several different tumor cell lines at a sub-micromolar level. Furthermore, results of fluorescence-activated cell sorting (FACS) analysis suggested that 12e induced cell cycle arrest in the G2/M phase accompanied by apoptosis in HL-60 and H460 cells. This action was confirmed by Hoechst staining and caspase-3 activation. Due to their easy synthesis and remarkable biological activities, 4-phenylquinolin-2(1H)-one analogs (4-PQs) are promising new anticancer leads based on the quinoline scaffold. Accordingly, compound 12e was identified as a new lead compound that merits further optimization and development as an anticancer candidate.

Effect of solvents on the spectroscopic properties of LD-489 & LD-473: estimation of ground and excited state dipole moments by solvatochromic shift method

The absorption and fluorescence spectra of 6,7,8,9-tetrahydro-6,8,9-trimethyl-4-(trifluoro methyl)-2H-pyrano[2,3-b][1,8]naphthyridin-2-one (LD-489) and 1,2,3,8-tetrahydro-1,2,3,3,8-pentamethyl-5-(trifluoromethyl)-7H-pyrrolo[3,2-g]quinolin-7-one (LD-473) have been recorded at room temperature in different solvents and 1,4-dioxane-acetonitrile solvent mixtures. The UV-Visible absorption spectra are less sensitive to solvent polarity than the corresponding fluorescence spectra in both the dyes which show pronounced solvatochromic effect. The effects of solvents upon the spectral properties are analyzed using Lippert-Mataga polarity function, Richardts microscopic solvent polarity parameter and Catalán's multiple linear regression approach. Both general solute-solvent interactions and specific interactions are operative in these systems. The solvatochromic correlations are used to estimate excited state dipole moments using experimentally determined ground state dipole moments. The excited state dipole moment for both the dyes are found to be larger than their corresponding ground state dipole moment and is interpreted based on their resonance structures.

TW01001, a novel piperazinedione compound, induces mitotic arrest and autophagy in non-small cell lung cancer A549 cells

Here, we report that TW01001, a novel piperazinedione compound, could be a new mitotic inhibitor for the treatment of non-small cell lung cancer by the following observations in A549 cells: (1) induction of cells to accumulate at G2/M phase, which ultimately led to cell apoptotic death, (2) accumulation of p53 and inhibition of survival signalings, and (3) induction of p53-independent autophagy. Taken together, our data suggested that TW01001 induces autophagy-p53-signaling pathway to cause mitotic arrest and cell growth inhibition in A549 cells and provides the framework for further development as a novel therapeutic agent for lung cancer treatment.