Combination of a novel microtubule inhibitor MBRI-001 and gemcitabine synergistically induces cell apoptosis by increasing DNA damage in pancreatic cancer cell lines

Determination of the effects of fusaric acid, a mycotoxin, on cytotoxicity, gamma-H2AX, 8-hydroxy-2 deoxyguanosine and DNA repair gene expressions in pancreatic cancer cells

Pancreatic cancer has a poor prognosis and is an important public health problem for developing countries. Oxidative stress plays an important role in cancer initiation, progression, proliferation, invasion, angiogenesis and metastasis. For this reason, one of the important strategic targets of new cancer therapeutics is to drive cancer cells into apoptosis through oxidative stress. In nuclear and mitochondrial DNA, 8-hydroxy-2'-deoxyguanosine and gamma-H2AX (γ-H2AX) are used as important oxidative stress biomarkers. Fusaric acid (FA) is a mycotoxin that mediates toxicity produced by Fusarium species and exhibits anticancer effects in various cancers via inducing apoptosis, cell cycle arrest, or other cellular mechanisms. The aim of this study was to determine the effects of fusaric acid on cytotoxic and oxidative damage in MIA PaCa-2 and PANC-1 cell lines. In this context, dose and time dependent cytotoxic effect of fusaric acid was determined by XTT method, mRNA expression levels of genes related to DNA repair were determined by RT-PCR, and its effect on 8-hydroxy-2'-deoxyguanosine and γ-H2AX levels was revealed by ELISA assay. According to XTT results, fusaric acid inhibits cell proliferation in MIA PaCa-2 and Panc-1 cells in a dose- and time-dependent manner. IC50 doses were determined as 187.74 μM at 48 h in MIA PaCa-2 cells and 134.83 μM at 48 h in PANC-1 cells, respectively. γ-H2AX and 8-OHdG changes were not found significant in pancreatic cancer cells. The mRNA expression levels of DNA repair-related genes NEIL1, OGG1, XRCC and Apex-1 change with exposure to fusaric acid. This study contributes to the therapeutic approaches to be developed for pancreatic cancer and demonstrates the potential of fusaric acid as an anticancer agent.

Design and syntheses of a bimolecular STING agonist based on the covalent STING antagonist

Cyclic GMP-AMP synthase and stimulator of interferon genes (cGAS-STING) signaling stimulators, an essential innate immunity component, monitor invading pathogen DNA and damaged self-DNA, making them an appealing target for drug development. The natural STING agonist, 2'3'-cGAMP, mounts and stabilizes the STING homodimer to trigger an antiviral or antitumor immune responses. However, cyclic-dinucleotide-based STING agonists show limited clinical effects owing to their short half-lives. To explore whether STING-dimer stabilizers could trigger STING signaling instead of cyclic dinucleotide-based molecules, we analyzed the structural characteristics of STING to design and synthesize a series of compounds based on the covalent STING inhibitor C-170, three of which were 23, 26, and 27, exhibited STING-dependent immune activation, both in vitro and in vivo. Compound 23 could act synergistically with cGAMP and other STING agonists as a promising moderate STING agonist. This indicates that promoting STING dimerization is a promising strategy for designing next-generation STING agonists.

A novel dipeptide type inhibitor of the Wnt/β-catenin pathway suppresses proliferation of acute myelogenous leukemia cells

The Wnt/β-catenin pathway is an attractive target for the treatment of acute myelogenous leukemia (AML), since aberrant activation of the Wnt/β-catenin pathway contributes to carcinogenesis in various types of cancers including AML. Screening of an in-house compound library, constructed at Kyoto Pharmaceutical University, identified a novel compound designated "31" that was found to be an inhibitor of the Wnt/β-catenin pathway. The compound inhibited T-cell factor (TCF) activity in a TCF firefly luciferase-reporter assay and suppressed the proliferation of several human AML cell lines in a dose-dependent manner. Compound 31 arrested the cell cycle of AML cells at the G1 stage and induced apoptosis. Decrease in protein and mRNA expression level of Wnt pathway-related molecules was confirmed by the analyses of western blotting and quantitative reverse transcription-polymerase chain reaction. In addition, compound 31 combined with idarubicin synergistically inhibited the proliferation of AML cells. In conclusion, these results strongly suggest that compound 31 has potential as a novel anti-AML agent targeting the Wnt/β-catenin signaling pathway.