Adiponectin is an adipokine increasing glucose and fatty acid metabolism and improving insulin sensitivity. The aim of this study was to investigate the role of adiponectin in the regulation of adipocyte lipolysis. Human adipocytes isolated from biopsies obtained during surgical operations from 16 non-obese and 17 obese subjects were incubated with 1) human adiponectin (20 μg/ml) or 2) 0.5 mM AICAR - activator of AMPK (adenosine monophosphate activated protein kinase). Following these incubations, isoprenaline was added (10-6 M) to investigate the influence of adiponectin and AICAR on catecholamine-induced lipolysis. Glycerol concentration was measured as lipolysis marker. We observed that adiponectin suppressed spontaneous lipolysis by 21 % and isoprenaline-induced lipolysis by 14 % in non-obese subjects. These effects were not detectable in obese individuals, but statistically significant differences in the effect of adiponectin between ob ese and non-obese were not revealed by two way ANOVA test. The inhibitory effect of AICAR and adiponectin on lipolysis was reversed by Compound C. Our results suggest, that adiponectin in physiological concentrations inhibits spontaneous as well as catecholamine-induced lipolysis. This effect might be lower in obese individuals and this regulation seems to involve AMPK., Z. Wedellová ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Non-small cell lung cancer (NSCLC) results in high mortality and has gained increasing attention. C-Phycocyanin (C-PC) has been identified as a potential therapeutic inhibitor for NSCLC, but its underlying mechanism remains obscure. The gene expression of the long noncoding RNA neighbour of BRCAI RNA 2 (NBR2) in NSCLC cells was evaluated by quantitative reverse transcription-PCR. The cell capacity for proliferation and migration was examined by EdU and wound-healing assays. Furthermore, the viability and apoptosis of cells was measured with CCK-8 and annexin V/PI, respectively. Next, the protein level of activation of adenosine monophosphate- activated protein kinase and the rapamycin kinase (mTOR) signalling pathway-associated molecules was evaluated by western blotting. H292 cells were pre-treated with C-PC or transfected with plasmids encoding NBR2 or the shNBR2 plasmid, to over-express or knock down NBR2 expression, respectively. NBR2 expression was robustly down-regulated in NSCLC cell lines compared with a normal cell line (BEAS-2B). NBR2 over-expression inhibited migration and promoted apoptosis of H292 cells. Treatment of H292 cells with C-PC enhanced NBR2 levels in a dose- and time-dependent manner. Downregulation of NBR2 in H292 cells inhibited the activity of C-PC on cell proliferation, viability and clone formation. Further mechanistic investigation showed that the down-regulation of NBR2 abolished the modulatory effects of C-PC on the AMPK/mTOR signalling pathway. In conclusion, C-PC inhibits H292 cell growth by enhancing the NBR2/AMPK signalling pathway.
Activation of autophagy suppresses ovarian cancer (OC). This in vitro study investigated whether the anti-tumour effect of exendin-4 against OC involves modulation of autophagy and figured out the possible mechanisms of action. SKOV-3 and OVCAR-3 cells (1 × 105/ml) were cultured in DMEM medium and treated with exendin-4 in the presence or absence of chloroquine (CQ), an autophagy inhibitor. In some cases, cells were also treated with exendin- 4 with or without pre-treatment with compound C (CC), an AMPK inhibitor, or insulin-like growth factor (IGF-1), a PI3K/Akt activator. Exendin-4 increased expression of beclin-1 and LC3I/II, suppressed expression of p62, reduced cell survival, migration, and invasion, and increased cell apoptosis and LDH release in both SKOV-3 and OVCAR-3 cells. Besides, exendin-4 reduced phosphorylation of mTORC1, 6SK, 4E-BP1, and Akt but increased phosphorylation of AMPK in both cell lines. These effects were associated with down-regulation of Bcl-2, suppression of nuclear phosphorylation of NF-κB p65, and increased expression of Bax and cleaved caspases 3/8. Chloroquine completely prevented the inhibitory effects of exendin-4 on the cell survival, Bcl-2, NF-κB, and cell invasiveness and abolished its stimulation of cell apoptosis and LDH release. Moreover, only the combined treatment with IGF-1 and CC completely abolished the observed effect of exendin-4 on the expression of beclin-1, LC3I/II, p62, as well as on cell survival, apoptosis, and LDH release. Exendin-4 exhibits a potent anti-tumour cytotoxic effect in SKOV-3 and OVCAR-3 cells by activating the markers of autophagy, mediated by activation of AMPK and inhibition of Akt.
Biguanidy jsou léky určené pro terapii hyperglykemie u diabetu 2. typu. V poslední době se ukazuje, že nejčastěji předepisovaný biguanid metformin vykazuje také protinádorový účinek. Jeho možné využití v protinádorové léčbě podporují epidemiologické, preklinické a klinické studie. Příznivé ovlivnění karcinomu prsu a tlustého střeva by mohlo souviset s primární schopností metforminu snižovat hladinu cirkulujícího inzulinu, ale metformin má nepochybně i přímý cytostatický efekt, který se uskutečňuje prostřednictvím inhibice mTOR (mammalian target of rapamycin) signální dráhy a blokádou syntézy proteinů. Využití metforminu v protinádorové léčbě nebo chemoprevenci nádorů ale ukáže teprve budoucnost., Metformin, an oral biguanide antidiabetic drug, is the most widely prescribed agent for treatment of type 2 diabetes. The drug mainly works by lowering glucose production by the liver, and thus lowering fasting blood glucose. Metformin acts as an insulin sensitizer, which leads to inhibition of gluconeogenesis in the liver, and has been found to be beneficial especially in overweight patients with diabetes. Metformin use has been postulated to contribute to a reduced risk of pancreatic, prostate, ovarian, and breast cancers. Metformin‘ s mechanism of action was examined recently and determined to be initiated by metformins role as an adenosine 5‘-mono-phosphate– activated protein kinase (AMPK) activator through a tumor suppressor protein kinase known as LKB-1, which regulates AMPK levels. Activation of AMPK has been shown to suppress the mammalian target of the rapamycin (mTOR) signaling pathway, leading to antiproliferative and antiangiogenic effects., Petra Tesařová, and Literatura 21