Songqiang Xie

DKK1 promotes hepatocellular carcinoma cell migration and invasion through β-catenin/MMP7 signaling pathway

BackgroundRecently several reports have indicated that elevated expression of DKK1 is tightly associated with the progression of hepatocellular carcinoma (HCC). However, the biological function of DKK1 in HCC has not yet been well documented.MethodsIn this study, the role of DKK1 in tumor cell proliferation, migration and invasion was investigated using MTT, colony formation, wound scratch, transwell assays, and also human HCC samples.ResultsBoth gain- and loss-of-function studies showed that DKK1 did not influence the tumor cell proliferation and colony formation, while dramatically promoted HCC cell migration and invasion. Subsequent investigations revealed that β-catenin was an important target of DKK1. The blocking of β-catenin by pharmacological inhibitor antagonized the function of DKK1, whereas introduction of β-catenin by transfection with plasmids or treatment with GSK3β inhibitor phenocopied the pro-migration and pro-invasion effects of DKK1. We further disclosed that DKK1 exerted its pro-invasion function, at least in part, by promoting β-catenin expression, in turn, upregulating the expression of matrix metalloproteinase 7 (MMP7), which was independent of the canonical Wnt signaling pathway. Moreover, introduction of MMP7 significantly enhanced the ability of HCC cells to invade extracellular matrix gel in vitro. Consistently, in human HCC tissues, DKK1 level was positively correlated with β-catenin expression, as well as tumor metastasis.ConclusionTaken together, these results demonstrated that DKK1 is overexpressed in HCC; moreover, ectopic expression DKK1 promotes HCC cell migration and invasion at least partly through β-catenin/MMP7 signaling axis, suggesting that DKK1 may be a promising target for HCC therapy.

Synthesis, cytotoxicity and apoptosis of naphthalimide polyamine conjugates as antitumor agents.

Several naphthalimide polyamine conjugates were synthesized and evaluated for in vitro cytotoxicity against human leukemia K562, murine melanoma B16, Chinese hamster ovary CHO cell lines. Both triamine moieties and the length of spacers were crucial in elevating the potency of 1,8-naphthalimide. The typical compounds 5a and 5d exhibited excellent cell selectivity to cancer cells through the human hepatoma BEL-7402 and human normal hepatocyte QSG-7701 screens. In addition, 5d could disturb the cell cycle in B16 cells. The research on caspase activity and cytochrome c indicated that 5d could induce B16 cell apoptosis via both the mitochondrial and membrane death receptor pathways, and the Bcl-2 family numbers were involved in the control of apoptosis.

A Nine-Coordinated Bismuth(III) Complex Derived from Pentadentate 2,6-Diacetylpyridine Bis(4N-methylthiosemicarbazone): Crystal Structure and Both in Vitro and in Vivo Biological Evaluation

Up to now, bismuth(III) complexes with thiosemicarbazones have been comparatively rare. Few in vivo biological studies have been carried out in comparison to the plentiful in vitro data. Here, an interesting nine-coordinated bismuth(III) complex, [Bi(H2L)(NO3)2]NO3 [1; H2L = 2,6-diacetylpyridine bis((4)N-methylthiosemicarbazone)], has been synthesized and structurally characterized. The analytical data reveal the formation of 1:1 (metal/ligand) stoichiometry. In vitro biological studies have indicated that the bismuth complex 1 has shown much higher antibacterial and anticancer activities than its parent ligand, especially with MIC = 10.66 μM against Bacillus cereus and Salmonella typhimurium and IC50 = 26.8 μM against K562 leukemia cells, respectively. More importantly, it also evidently inhibits H22 xenograft tumor growth on tumor-bearing mice (10 mg/kg; inhibitory rate = 61.6%). These results indicate that coordination to bismuth(III) might be an interesting strategy in the discovery of new anticancer drug candidates.

Conjugation of substituted naphthalimides to polyamines as cytotoxic agents targeting the Akt/mTOR signal pathway.

Though several naphthalimide derivatives have exhibited antitumor activity in clinical trials, some issues such as toxicity prompted further structural modifications on the naphthalimide backbone. A series of naphthalimides conjugated with polyamines were synthesized to harness the polyamine transporter (PAT) for drug delivery, which was beneficial for the tumor cell selectivity. Bioevaluation in human hepatoma HepG2 cells treated with alpha-difluoromethylornithine (DFMO) or spermidine (Spd), human hepatoma Bel-7402 and normal QSG-7701 hepatocyte confirmed the PAT recognition and cell selectivity. In addition, the novel naphthalimide polyamine conjugate kills cells via apoptosis, and the Akt/mTOR signal pathway was first identified as the upstream cellular target through the apoptotic mechanism research. The presence of DFMO or Spd only either elevated or attenuated the cell apoptosis, but did not change the signal pathway. Collectively, the proper polyamine recognition element (i.e., homospermidine) mediated effective drug delivery via the PAT, and helped the proper cytotoxic goods (i.e., diverse naphthalimides) exert antitumor properties.

Nonhematotoxic Naphthalene Diimide Modified by Polyamine: Synthesis and Biological Evaluation

With the aim of up-regulating antitumor efficacy and down-regulating adverse effects, three types of aromatic imide and diimides were designed to couple with different polyamines. The in vitro assays revealed that two naphthalene diimide-polyamine conjugates could inhibit the growth of multiple cancer cell lines more potently than amonafide. 9f, the most potent compound, was verified to efficiently induce apoptosis via a ROS mediated mitochondrial pathway in a preliminary mechanistic study. The comprehensive in vivo trials on three H22 tumor transplant models demonstrated that 9f improved the indexes in terms of inhibitive effect and lifespan extension and reduced the hematotoxicity which is one of main drawbacks of amonafide. More importantly, the obviously elevated ability in preventing lung cancer metastasis was observed, which increased the value of 9f as a promising lead compound. This work supported that the versatile function of polyamines may endow some intriguing biological features to the parent drugs.

Design, synthesis and evaluation of novel 7-aminoalkyl-substituted flavonoid derivatives with improved cholinesterase inhibitory activities.

A novel series of 7-aminoalkyl-substituted flavonoid derivatives 5a-5r were designed, synthesized and evaluated as potential cholinesterase inhibitors. The results showed that most of the synthesized compounds exhibited potent acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities at the micromolar range. Compound 2-(naphthalen-1-yl)-7-(8-(pyrrolidin-1-yl)octyloxy)-4H-chromen-4-one (5q) showed the best inhibitory activity (IC50, 0.64μM for AChE and 0.42μM for BChE) which were better than our previously reported compounds and the commercially available cholinergic agent Rivastigmine. The results from a Lineweaver-Burk plot indicated a mixed-type inhibition for compound 5q with AChE and BChE. Furthermore, molecular modeling study showed that 5q targeted both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. Besides, these compounds (5a-5r) did not affect PC12 and HepG2 cell viability at the concentration of 10μM. Consequently, these flavonoid derivatives should be further investigated as multipotent agents for the treatment of Alzheimers disease.

Antitumor conjugates with polyamine vectors and their molecular mechanisms

Importance of the field: A polyamine conjugate is a special polyamine derivative composed of polyamine vectors appended directly or by a linker to a cargo with specific biological functions. In recent years, extensive researches have emphasized the fact that polyamine conjugates acting as promising antitumor candidates are becoming increasingly important in the polyamine field. Areas covered in this review: Two key subjects are illustrated in this review. First, various drug-polyamine conjugates and relevant structure–activity relationships are discussed with a focus on the molecular recognition of polyamine transport system (PTS). Second, the design of polyamine conjugates is following a rational mechanism-based strategy. Therefore, it is critically important to understand the intrinsic properties of PTS on the cell membrane, enhanced pharmacological effects of polyamine vector on cellular components, and resulting comprehensive signaling networks. What the reader will gain: A general design strategy of polyamine conjugates as well as recent progress in both fundamental mechanism studies and preclinical therapies are provided for the readers. Take home message: The multiple functions of polyamine moieties in objective conjugates furnish broad development space for more efficacious antitumor agents.

3-Nitro-naphthalimide and nitrogen mustard conjugate NNM-25 induces hepatocellular carcinoma apoptosis via PARP-1/p53 pathway

Hepatocellular carcinoma (HCC) is one of the main causes of death in cancer. Some naphthalimide derivatives exert high anti-proliferative effects on HCC. In this study, it is confirmed that 3-nitro-naphthalimide and nitrogen mustard conjugate (NNM-25), a novel compound conjugated by NNM-25, displayed more potent therapeutic action on HCC, both in vivo and in vitro, than amonafide, a naphthalimide drug in clinical trials. More importantly, preliminary toxicological evaluation also supported that NNM-25 exhibited less systemic toxicity than amonafide at the therapeutic dose. The antitumor mechanism of conjugates of naphthalimides with nitrogen mustard remains poorly understood up to now. Here, we first reported that apoptosis might be the terminal fate of cancer cells treated with NNM-25. Inhibition of p53 by siRNA resulted in a significant decrease of NNM-25-induced apoptosis, which corroborated that p53 played a vital role in the cell apoptosis triggered by NNM-25. NNM-25 inhibited the PARP-1 activity, AKT phosphorylation, up-regulated the protein expression of p53, Bad, and mTOR as well as down-regulating the protein expression of Bcl-2 and decreasing mitochondrial membrane potential. It also facilitated cytochrome c release from mitochondria to cytoplasm, activated caspase 8, caspase 9, and caspase 3 in HepG2 cells in vitro, as also authenticated in H22 tumor-bearing mice in vivo. Collectively, the conjugation of naphthalimides with nitrogen mustard provides favorable biological activity and thus is a valuable strategy for future drug design in HCC therapy.

Polyamine transporter recognization and antitumor effects of anthracenymethyl homospermidine.

This study was conducted to examine the polyamine transporter (PAT) recognization and antitumor effects of anthracenymethyl homospermidine (ANTMHspd) and its apoptotic mechanism in B16 melanoma cells. ANTMHspd promoted a dose-dependent apoptosis in B16 melanoma cells and the apoptosis was associated with the excellent PAT recognization, externalization of cell membrane phosphatidylserine and the disruption of mitochondria, these processes were correlated with up-regulation of polyamine oxidase, an increase in intracellular reactive oxygen species (ROS) production and oxidative stress. In addition, reduction of MMP, release of cytochrome c, up-regulation of Bax protein expression, down-regulation of Bcl-2 protein expression, and activation of caspase-3, caspase-9 were also observed in B16 cells after treatment with ANTMHspd. Furthermore, N-acetylcysteine obviously antagonized ANTMHspd-induced apoptosis. Importantly, ANTMHspd was found to be better tolerated and revealed potent antitumor effect on inhibiting tumor growth in situ and suppressing pulmonary metastasis in xenograft mice model. These data demonstrate that ANTMHspd is an excellent PAT recognization and potent antitumor agent.

Essential role of autophagy in fucoxanthin-induced cytotoxicity to human epithelial cervical cancer HeLa cells

Aim:To investigate the effects and the molecular mechanisms of fucoxanthin, a major carotenoid found in edible seaweed, on HeLa cells.Methods:The cytotoxicity of fucoxanthin was evaluated using MTT assay. Cell cycle and apoptosis were evaluated using flow cytometric analysis. Autophagy was detected with acridine orange staining and transient transfection of the GFP-LC3 plasmid into the cells. Protein expression was detected with Western blotting.Results:Treatment of HeLa cells with fucoxanthin (10–80 μmol/L) for 48 h caused dose-dependent cytotoxicity with an IC50 value of 55.1±7.6 μmol/L. Fucoxanthin (10, 20, and 40 μmol/L) dose-dependently induced G0/G1 arrest, but did not change the apoptosis of HeLa cells. The same concentrations of fucoxanthin dose-dependently increased the protein expression of LC3 II (the autophagosome marker) and Beclin 1 (the initiation factor for autophagosome formation) in HeLa cells. Moreover, fucoxanthin dose-dependently decreased the levels of phosphorylated Akt and its downstream proteins p53, p70S6K, and mTOR, and increases the expression of PTEN in HeLa cells. Pretreatment of HeLa cells with 3-methyladenine (5 mmol/L) blocked the cytotoxic effect of fucoxanthin as well as fucoxanthin-induced autophagy.Conclusion:Fucoxanthin exerts autophagy-dependent cytotoxic effect in HeLa cells via inhibition of Akt/mTOR signaling pathway.