Hongxia Liu

Discovery of benzimidazole derivatives as novel multi-target EGFR, VEGFR-2 and PDGFR kinase inhibitors.

Multi-target EGFR, VEGFR-2 and PDGFR inhibitors are highly useful anticancer agents with improved therapeutic efficacies. In this work, we used two virtual screening methods, support vector machines (SVM) and molecular docking, to identify a novel series of benzimidazole derivatives, 2-aryl benzimidazole compounds, as multi-target EGFR, VEGFR-2 and PDGFR inhibitors. 2-Aryl benzimidazole compounds were synthesized and their biological activities against a tumor cell line HepG-2 and specific kinases were evaluated. Among these compounds, compounds 5a and 5e exhibited high cytotoxicity against HepG-2 cells with IC₅₀ values at ∼2 μM. Further kinase assay study showed that compound 5a have good EGFR inhibitory activity and moderate VEGFR-2 and PDGFR inhibitory activities, while 5e have moderate EGFR inhibitory activity and slightly weaker VEGFR-2 and PDGFR inhibitory activities. Molecular docking analysis suggested that compound 5a more tightly interacts with EGFR and PDGFR than compound 5e. Our study discovered a novel series of benzimidazole derivatives as multi-target EGFR, VEGFR-2 and PDGFR kinases inhibitors.

Exploration of acridine scaffold as a potentially interesting scaffold for discovering novel multi-target VEGFR-2 and Src kinase inhibitors.

VEGFR-2 and Src kinases both play important roles in cancers. In certain cancers, Src works synergistically with VEGFR-2 to promote its activation. Development of multi-target drugs against VEGFR-2 and Src is of therapeutic advantage against these cancers. By using molecular docking and SVM virtual screening methods and based on subsequent synthesis and bioassay studies, we identified 9-aminoacridine derivatives with an acridine scaffold as potentially interesting novel dual VEGFR-2 and Src inhibitors. The acridine scaffold has been historically used for deriving topoisomerase inhibitors, but has not been found in existing VEGFR-2 inhibitors and Src inhibitors. A series of 21 acridine derivatives were synthesized and evaluated for their antiproliferative activities against K562, HepG-2, and MCF-7 cells. Some of these compounds showed better activities against K562 cells in vitro than imatinib. The structure-activity relationships (SAR) of these compounds were analyzed. One of the compounds (7r) showed low μM activity against K562 and HepG-2 cancer cell-lines, and inhibited VEGFR-2 and Src at inhibition rates of 44% and 8% at 50μM, respectively, without inhibition of topoisomerase. Moreover, 10μM compound 7r could reduce the levels of activated ERK1/2 in a time dependant manner, a downstream effector of both VEGFR-2 and Src. Our study suggested that acridine scaffold is a potentially interesting scaffold for developing novel multi-target kinase inhibitors such as VEGFR-2 and Src dual inhibitors.

Novel synthetic 2-amino-10-(3,5-dimethoxy)benzyl-9(10H)-acridinone derivatives as potent DNA-binding antiproliferative agents

A series of novel 9(10H)-acridinone derivatives with terminal amino substituents at C2 position on the acridinone ring were synthesized and studied for their antiproliferative activity and underlying mechanisms. These compounds demonstrated promising cytotoxicity to leukemia cells CCRF-CEM, displaying IC(50) values in the low micromolar range. Structure-activity relationships (SAR) indicated that the compound 6d bearing a pyrrolidine substituent and 8a with a methyl ammonium side chain displayed higher cytotoxicity to CCRF-CEM cells and also solid tumor cells A549, HepG2, and MCF7. Furthermore, the compounds 6d and 8a had strong binding activity to calf thymus DNA (ct DNA), as detected by UV absorption and fluorescence quenching assays, but limited inhibitory activity to human topoisomerase 1 (topo 1). Taken together, this study discovered a series of new synthetic 9(10H)-acridinone derivatives with potent DNA binding and anticancer activity.

Synthesis and biological evaluation of benzimidazole acridine derivatives as potential DNA-binding and apoptosis-inducing agents

The discovery of new effective DNA-targeted antitumor agent is needed because of their clinical significance. As acridines can intercalate into DNA and benzimidazoles have the ability to bind in the DNA minor groove, a series of novel benzimidazole acridine derivatives were designed and synthesized to be new DNA-targeted compounds. MTT assay indicated that most of the synthesized compounds displayed good antiproliferative activity, among which compound 8l demonstrated the highest activity against both K562 and HepG-2 cells. Further experiments showed that 8l displayed good DNA-binding capability and inhibited topoisomerase I activity. Moreover, compound 8l could induce apoptosis in K562 cell lines through mitochondrial pathway. These data suggested that compound 8l might be potential as new DNA-binding and apoptosis-inducing antitumor agents.

microRNA 21‐mediated suppression of sprouty1 by Pokemon affects liver cancer cell growth and proliferation

Transcriptional repressor Pokemon is a critical factor in embryogenesis, development, cell proliferation, differentiation, and oncogenesis, thus behaving as an oncogene. Oncomine database suggests a potential correlation between the expressions of Pokemon and Sprouty1. This study investigated the regulatory role of Pokemon in Sprouty1 expression and the effect on liver cancer cell growth and proliferation, revealing a novel miR‐21‐mediated regulatory circuit. In normal (HL‐7702) and cancer (QGY‐7703) liver cell lines, Sprouty1 expression is inversely correlated with Pokemon levels. Targeted expression or siRNA‐mediated silencing showed that Pokemon is a repressor of Sprouty1 expression at both mRNA and protein levels, but Pokemon cannot affect the promoter activity of Sprouty1. Sprouty1 is a target of miR‐21 and interestingly, we found that miR‐21 is up‐regulated by Pokemon in liver cancer cells. Luciferase reporter assays showed that Pokemon up‐regulated miR‐21 transcription in a dose‐dependent manner, and ChIP assay exhibited a direct binding of Pokemon to the miR‐21 promoter at −747 to −399 bp. Site‐directed mutagenesis of the GC boxes at −684 to −679 bp and −652 to −647 bp of miR‐21 promoter abolished the regulatory activity by Pokemon. Furthermore, we found that the modulation of Pokemon and miR‐21 expression affected the growth and proliferation of liver cancer cells QGY‐7703. In summary, our findings demonstrate that Pokemon suppresses Sprouty1 expression through a miR‐21‐mediated mechanism, affecting the growth and proliferation of liver cancer cells. This study recognized miR‐21 and Sprouty1 as novel targets of the Pokemon regulatory network. J. Cell. Biochem. 114: 1625–1633, 2013.

Design, synthesis and evaluation of acridine derivatives as multi-target Src and MEK kinase inhibitors for anti-tumor treatment.

Clinical studies have shown enhanced anticancer effects of combined inhibition of Src and MEK kinases. Development of multi-target drugs against Src and MEK is of potential therapeutic advantage against cancers. As a follow-up of our previous studies, and by using molecular docking method, we designed and synthesized a new series of 9-anilinoacridines containing phenyl-urea moieties as potential novel dual Src and MEK inhibitors. The anti-proliferative assays against K562 and HepG-2 tumor cells showed that most of the derivatives displayed good cytotoxicity in vitro. In particular, kinase inhibition assays showed that compound 8m inhibited Src (59.67%) and MEK (43.23%) at 10 μM, and displayed moderate inhibitory activity against ERK and AKT, the downstream effectors of both Src and MEK. Moreover, compound 8m was found to induce K562 cells apoptosis. Structure-activity relationships of these derivatives were analyzed. Our study suggested that acridine scaffold, particularly compound 8m, is of potential interest for developing novel multi-target Src and MEK kinase inhibitors.

A POCl3-mediated synthesis of substituted fused azoacridones derivatives

A highly facile and efficient approach to synthesize fused azoacridone derivatives containing various functional groups has been developed. This reaction starts with a substitution reaction between the corresponding benzoic acids and pyrimidines, followed by POCl3-mediated cyclization reaction. The desired pure fused azoacridones were afforded in high yields.

2′-Chloro-4′-aminoflavone Derivatives Selectively Targeting Hepatocarcinoma Cells: Convenient Synthetic Process, G2/M Cell Cycle Arrest and Apoptosis Triggers

A series of 2′‐chloro‐4′‐nitroflavone and 2′‐chloro‐4′‐aminoflavone derivatives were synthesized by a convenient synthetic process. The in vitro anti‐proliferation ability of these compounds was evaluated against hepatocarcinoma cells (HepG2), breast adenocarcinoma cells (MCF‐7), and human chronic myelogenous leukemia cells (K562). Most of synthetic compounds possessed notable anti‐proliferation activity against HepG2 cells and little activity against MCF‐7 cells and K562 cells. In particular, compounds 4c and 4e exhibited high anti‐proliferation activity against HepG2 cells with IC50 at about 2.0 µM. Further toxicity screening toward normal human hepatocytes indicated that some compounds had low toxicity against normal liver cells, among which 4e displayed very weak effects on QSG7701 and HL7702 cells, with IC50 values >100 and 50 µM, respectively. Compound 4c, with the best anti‐proliferation activity in amino‐substituted flavones (IC50 = 2.0 µM), was selected for further evaluation of its effects on apoptosis and the cell cycle. HepG2 cells were exposed to this compound at 10 µM, which induced nuclear disassembly and DNA fragmentation. Flow cytometry analysis suggested that the population of apoptotic cells greatly increased in the 4c‐treated HepG2 cells, and the cell cycle was arrested at the G2/M phase.

Hydrogel microfibers with perfusable folded channels for tissue constructs with folded morphology

Fiber-based materials with microchannels have drawn considerable attention in recent years owing to their ability to mimic intrinsic morphologies of living tissues. Folded morphologies, which are common in vivo, such as in skeletal muscle capillaries and intestine luminal endoderm, play important roles in the achievement of tissue functions. Here, microfibers with folded hollow channels are fabricated. Channel morphologies, such as straight-folded, double-folded and double-helical channels, can be regulated by adjusting flow conditions in the microfluidic devices. To further demonstrate the potential to be used in tissue engineering, intestine and skeletal muscle constructs are fabricated using these microfibers as building blocks. Furthermore, the properties of perfusability, permeability, cytocompatibility and weavability of the microfibers are evaluated. The asymmetric molecular distributions in the microfibers provide promising platforms for the study of nutrient exchange and energy supplement between normal and tortuous tissues. The new features of biofibers and proof-of-concept of tissue constructs with folded morphologies may contribute to the development of regenerative medicine and drug screening in the future.