The present study describes the synthesis and anticancer activity of novel octahedral PtIV complexes with cyclohexyl functionalized ethylenediamine‐N,N′‐diacetate‐type ligands. Molecular mechanics ...calculations and density functional theory analysis revealed that s‐cis is the preferred geometry of these PtIV complexes with tetradentate‐coordinated (S,S)‐ethylenediamine‐N,N′‐di‐2‐(3‐cyclohexyl)propanoate. The viability of cancer cell lines (U251 human glioma, C6 rat glioma, L929 mouse fibrosarcoma, and B16 human melanoma) was assessed by measuring mitochondrial dehydrogenase activity and lactate dehydrogenase release. Cell‐cycle distribution, oxidative stress, caspase activation, and induction of autophagy were analyzed by flow cytometry using appropriate fluorescent reporter dyes. The cytotoxic activity of novel PtIV complexes against various cancer cell lines (IC50 range: 1.9–8.7 μM) was higher than that of cisplatin (IC50 range: 10.9–67.0 μM) and proceeded through completely different mechanisms. Cisplatin induced caspase‐dependent apoptosis associated with the cytoprotective autophagic response. In contrast, the new PtIV complexes caused rapid, caspase‐independent, oxidative stress‐mediated non‐apoptotic cell death characterized by massive cytoplasmic vacuolization, cell membrane damage, and the absence of protective autophagy.
Octahedral PtIV complexes with cyclohexyl group functionalized edda‐type ligands kill tumor cells via oxidative stress‐mediated caspase‐independent necrosis‐like cell death associated with massive cytoplasmic vacuolization.
The antihyperglycaemic drug metformin reduces food consumption through mechanisms that are not fully elucidated. The present study investigated the effects of intracerebroventricular administration ...of metformin on food intake and hypothalamic appetite-regulating signalling pathways induced by the orexigenic peptide ghrelin.
Rats were injected intracerebroventricularly with ghrelin (5 µg), metformin (50, 100 or 200 µg), 5-amino-imidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR, 25 µg) and L-leucine (1 µg) in different combinations. Food intake was monitored during the next 4 h. Hypothalamic activation of AMP-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC), regulatory-associated protein of mTOR (Raptor), mammalian target of rapamycin (mTOR) and p70 S6 kinase 1 (S6K) after 1 h of treatment was analysed by immunoblotting.
Metformin suppressed the increase in food consumption induced by intracerebroventricular ghrelin in a dose-dependent manner. Ghrelin increased phosphorylation of hypothalamic AMPK and its targets ACC and Raptor, which was associated with the reduced phosphorylation of mTOR. The mTOR substrate, S6K, was activated by intracerebroventricular ghrelin despite the inhibition of mTOR. Metformin treatment blocked ghrelin-induced activation of hypothalamic AMPK/ACC/Raptor and restored mTOR activity without affecting S6K phosphorylation. Metformin also reduced food consumption induced by the AMPK activator AICAR while the ghrelin-triggered food intake was inhibited by the mTOR activator L-leucine.
Metformin could reduce food intake by preventing ghrelin-induced AMPK signalling and mTOR inhibition in the hypotalamus.
Hepatotoxicity of the antidiabetic drug metformin has been reported, but the underlying mechanisms remain unclear. We here investigated the effect of metformin in immune-mediated liver damage. While ...not hepatotoxic alone, metformin (200 mg/kg) aggravated concanavalin A (Con A, 12 mg/kg)-induced hepatitis, an experimental model of T cell-mediated liver injury, in both relatively resistant BALB/c and highly susceptible C57Bl/6 mice. Metformin + Con A-treated mice had elevated serum levels of pro-inflammatory cytokines TNF-α and IFN-γ, accompanied by a massive mononuclear cell infiltration in the liver. This was associated with the higher numbers of CD4
+
T cells producing TNF-α, IFN-γ and IL-17, CD4
+
T cells expressing chemokine receptor CXCR3 and activation marker CD27, CD4
+
CD62L
−
CCR7
−
and CD8
+
CD62L
−
CCR7
−
effector memory cells, IFN-γ producing NK cells, IL-4 and IL-17 producing NKT cells and IL-12 producing macrophages/dendritic cells. The percentage of CD4
+
CXCR3
+
Tbet
+
IL-10
+
and CD4
+
CD69
+
CD25
−
regulatory T cells was reduced. Metformin stimulated inducible nitric oxide synthase (iNOS) expression in the liver and spleen, and genetic deletion of iNOS attenuated the hepatotoxicity of metformin. Metformin increased the autophagic light chain 3 conversion and mRNA expression of important autophagy-inducing (beclin-1, Atg5 and GABARAP) and pro-apoptotic (p21, p27, Puma, Noxa, Bax, Bad, Bak1, Bim and Apaf1), but not anti-apoptotic molecules (Bcl-xL, survivin and XIAP), which correlated with the apoptotic caspase-3/PARP cleavage in the liver. The autophagy inhibitor chloroquine (20 mg/kg) prevented liver injury and apoptotic changes induced by metformin. Therefore, metformin aggravates immune-mediated hepatitis by promoting autophagy and activation of immune cells, affecting effector, as well as liver-specific regulatory T cells and iNOS expression.
The protective ability of novel arylpiperazine‐based dopaminergic ligands against nitric oxide (NO)‐mediated neurotoxicity is investigated. The most potent neuroprotective arylpiperazine identified ...during the study was N‐{4‐2‐(4‐phenyl‐piperazin‐1‐yl)ethyl‐phenyl}picolinamide, which protected SH‐SY5Y human neuron‐like cells from the proapoptotic effect of NO donor sodium nitroprusside (SNP) by decreasing oxidative stress, mitochondrial membrane depolarization, caspase activation and subsequent phosphatydilserine externalization/DNA fragmentation. The protective effect was associated with the inhibition of proapoptotic (JNK, ERK, AMPK) and activation of antiapoptotic (Akt) signaling pathways, in the absence of interference with intracellular NO accumulation. The neuroprotective action of arylpiperazines was shown to be independent of dopamine receptor binding, as it was not affected by the high‐affinity D1/D2 receptor blocker butaclamol. These results reported support the further study of arylpiperazines as potential neuroprotective agents.
Guarding the grey matter! Arylpiperazine dopaminergic ligands protect neurons from nitric oxide cytotoxicity. Their ability to modulate cell survival signaling pathways, stabilize mitochondrial membrane, and ultimately prevent neuronal apoptosis, makes them plausible candidates for treatment of neurodegenerative diseases.
Five 3d metal M(H2O)2(SQ)n complexes, where M is Mn, Co, Ni, Zn and Cu, and SQ is the dianion of 8-hydroxyquinoline-5-sulfonic acid exhibit moderate but selective anticancer activity against cervical ...carcinoma HeLa and colon carcinoma HCT116 cell lines. All complexes were characterized by IR spectroscopy and elemental analysis, two of them by X-ray structure analysis.
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•M(H2O)2(SQ)n complexes (M = Mn, Co, Ni, Cu, Zn; SQ = 8-HQ-5-sulfonic acid anion).•Anticancer activity is exceptional, the best results showed Mn(H2O)2(SQ)n.•Mn(H2O)2(SQ)n arrests S phase of HCT116 and HeLa (IC50 < 39 μM).•Mn(H2O)2(SQ)n is selectively cytotoxic.•Antimicrobial activity is negligible.
Five 3d metal M(H2O)2(SQ)n complexes, where M is Mn (1), Co (2), Ni (3), Zn (4) and Cu (5), and SQ is the dianion of 8-hydroxyquinoline-5-sulfonic acid have been prepared and characterized by IR spectroscopy and elemental analysis. X-ray structure analysis of 1 and 5 in combination with IR spectroscopy of all five complexes showed that complexes 1–4 are isostructural 2D polymers, while 5 is 1D polymer due to the different bonding character of SQ. Stability of all complexes in DMSO was proved by UV–Vis spectroscopy and for 4 also verified by 1H and 13C NMR spectroscopy. Cytotoxic activity tests against cervical carcinoma HeLa, colon carcinoma HCT116 and normal human fibroblast MRC-5 cell lines showed moderate but selective cytotoxicity of all complexes. Complex 1 exhibited highest activity with IC50 = 39.1 and 33.4 µM, respectively, but is lower than activity of cisplatin (CP) which IC50 = 24.3 and 14.3 µM, respectively. However, their cytotoxic activity against healthy MRC-5 cells (IC50 > 92 µM) is much lower than CP (IC50 = 19.7 µM). Antimicrobial activity of all complexes against 9 strains of pathogenic bacteria, five mould species and two yeast species is negligible.
To sustain their proliferative and metastatic capacity, tumor cells increase the activity of energy-producing pathways and lysosomal compartment, resorting to autophagolysosomal degradation when ...nutrients are scarce. Consequently, large fragile lysosomes and enhanced energy metabolism may serve as targets for anticancer therapy. A simultaneous induction of energy stress (by caloric restriction and inhibition of glycolysis, oxidative phosphorylation, Krebs cycle, or amino acid/fatty acid metabolism) and lysosomal stress (by lysosomotropic detergents, vacuolar ATPase inhibitors, or cationic amphiphilic drugs) is an efficient anti-cancer strategy demonstrated in a number of studies. However, the mechanisms of lysosomal/energy stress co-amplification, apart from the protective autophagy inhibition, are poorly understood. We here summarize the established and suggest potential mechanisms and candidates for anticancer therapy based on the dual targeting of lysosomes and energy metabolism.
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•Tumor cells increase energy metabolism and lysosome activity to sustain fast growth.•Various energy and lysosomal stressors synergize in selective cancer cell killing.•Energy and lysosomal stress damage cancer cells via multiple positive feedbacks.•Combining energy and lysosomal stress is a potential anticancer strategy.
We investigated the effect of compound C, a well-known inhibitor of the intracellular energy sensor AMP-activated protein kinase (AMPK), on proliferation and viability of human U251 and rat C6 glioma ...cell lines. Compound C caused G
2/M cell cycle block, accompanied by apoptotic glioma cell death characterized by caspase activation, phosphatidylserine exposure and DNA fragmentation. The mechanisms underlying the pro-apoptotic action of compound C involved induction of oxidative stress and downregulation of antiapoptotic molecule Bcl-2, while no alteration of pro-apoptotic Bax was observed. Compound C diminished AMPK phosphorylation and enzymatic activity, resulting in reduced phosphorylation of its target acetyl CoA carboxylase. AMPK activators metformin and AICAR partly prevented the cell cycle block, oxidative stress and apoptosis induced by compound C. The small interfering RNA (siRNA) targeting of human AMPK mimicked compound C-induced G
2/M cell cycle arrest, but failed to induce oxidative stress and apoptosis in U251 glioma cells. In conclusion, our data indicate that AMPK inhibition is required, but not sufficient for compound C-mediated apoptotic death of glioma cells.
To explore combined antiglioma effect of nitric oxide (NO) and hyperthermia, the rat C6 and human U251 glioma cells were exposed to NO-releasing agents sodium nitroprusside(SNP), S-nitrosoglutathione ...or PAPA-NONOate, followed by hyperthermia (1 h, 43 °C). While each treatment alone showed only moderate efficiency, a synergistic cytotoxicity of NO donors and hyperthermia was clearly demonstrated by crystal violet and MTT cytotoxicity assays. The flow cytometric analysis with the appropriate reporter fluorochromes confirmed that hyperthermia and SNP cooperated in inducing oxidative stress, mitochondrial depolarization, caspase activation and DNA fragmentation, leading to both necrotic and caspase-dependent apoptotic cell death. The acridine orange staining of intracellular acidic compartments revealed that SNP completely blocked hyperthermia-induced autophagy, while the inhibition of autophagy by 3-methyl adenine mimicked SNP-triggered oxidative stress, caspase activation and cell death in hyperthermia-exposed cells. Therefore, the synergistic cytotoxicity of SNP and hyperthermia could result from NO-mediated suppression of protective autophagic response in glioma cells.
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