It was evidenced that saturated fatty acids (FAs) have a detrimental effect on pancreatic β-cells function and survival, leading to endoplasmic reticulum (ER) calcium release, ER stress, and apoptosis. In the present study, we have tested the effect of three calcium influx inhibitors, i.e., diazoxide, nifedipine, and verapamil, on the apoptosis-inducing effect of saturated stearic acid (SA) in the human pancreatic β-cell lines NES2Y and 1.1B4. We have demonstrated that the application of all three calcium influx inhibitors tested has no inhibitory effect on SA-induced ER stress and apoptosis in both tested cell lines. Moreover, these inhibitors have pro-apoptotic potential per se at higher concentrations. Interestingly, these findings are in contradiction with those obtained with rodent cell lines and islets. Thus our data obtained with human β-cell lines suggest that the prospective usage of calcium channel blockers for prevention and therapy of type 2 diabetes mellitus, developed with the contribution of the saturated FA-induced apoptosis of β-cells, seems rather unlikely.

• Klíčová slova
• 1.1B4, Apoptosis, Calcium influx, Diazoxide, Fatty acids, NES2Y, Nifedipine, Pancreatic β-cells, Type 2 diabetes mellitus, Verapamil,
• Publikační typ
• časopisecké články MeSH

Saturated fatty acids (FAs) induce apoptosis in the human pancreatic NES2Y β-cell line while unsaturated FAs have nearly no detrimental effect. Moreover, unsaturated FAs are capable of inhibiting the pro-apoptotic effect of saturated FAs. Hypoxia is also known to have deleterious effects on β-cells function and viability. In the present study, we have tested the modulatory effect of hypoxia on the effect of FAs on the growth and viability of the human pancreatic NES2Y β-cells. This study represents the first study testing hypoxia effect on effects of FAs in pancreatic β-cells as well as in other cell types. We showed that hypoxia increased the pro-apoptotic effect of saturated stearic acid (SA). Endoplasmic reticulum stress signaling seemed to be involved while redistribution of FA transporters fatty acid translocase/cluster of differentiation 36 (FAT/CD36) and fatty acid-binding protein (FABP) do not seem to be involved in this effect. Hypoxia also strongly decreased the protective effect of unsaturated oleic acid (OA) against the pro-apoptotic effect of SA. Thus, in the presence of hypoxia, OA was unable to save SA-treated β-cells from apoptosis induction. Hypoxia itself had only a weak detrimental effect on NES2Y cells. Our data suggest that hypoxia could represent an important factor in pancreatic β-cell death induced and regulated by FAs and thus in the development of type 2 diabetes mellitus.

• Klíčová slova
• ER stress, NES2Y, apoptosis, caspases, fatty acid transporters, fatty acids, hypoxia, hypoxia-inducible factor 1α, pancreatic β-cells,
• MeSH
• beta-buňky metabolismus   MeSH
• biologické markery MeSH
• buněčné linie MeSH
• hypoxie metabolismus   MeSH
• kaspasy metabolismus   MeSH
• lidé MeSH
• mastné kyseliny metabolismus   MeSH
• proliferace buněk MeSH
• signální transdukce účinky léků   MeSH
• stres endoplazmatického retikula MeSH
• viabilita buněk MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• biologické markery MeSH
• kaspasy MeSH
• mastné kyseliny MeSH

It has been shown that saturated fatty acids (FAs) have a detrimental effect on pancreatic β-cells function and survival, leading to apoptosis, whereas unsaturated FAs are well tolerated and are even capable of inhibiting the pro-apoptotic effect of saturated FAs. Molecular mechanisms of apoptosis induction and regulation by FAs in β-cells remain unclear; however, mitogen-activated protein (MAP) kinase and endoplasmic reticulum (ER) stress signaling pathways may be involved. In this study, we tested how unsaturated oleic acid (OA) affects the effect of saturated stearic acid (SA) on the p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) pathways as well as the ER stress signaling pathways during apoptosis induction in the human pancreatic β-cells NES2Y. We demonstrated that OA is able to inhibit all effects of SA. OA alone has only minimal or no effects on tested signaling in NES2Y cells. The point of OA inhibitory intervention in SA-induced apoptotic signaling thus seems to be located upstream of the discussed signaling pathways.

• Klíčová slova
• NES2Y, apoptosis, endoplasmic reticulum (ER) stress, extracellular signal-regulated kinase (ERK), fatty acids, p38 mitogen-activated protein kinase (MAPK), pancreatic β-cells,
• MeSH
• apoptóza * MeSH
• beta-buňky cytologie   metabolismus   patologie   MeSH
• buněčné linie MeSH
• kyselina olejová metabolismus   MeSH
• kyseliny stearové metabolismus   MeSH
• lidé MeSH
• MAP kinasový signální systém * MeSH
• mitogenem aktivované proteinkinasy p38 metabolismus   MeSH
• stres endoplazmatického retikula * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kyselina olejová MeSH
• kyseliny stearové MeSH
• mitogenem aktivované proteinkinasy p38 MeSH

The development of drug resistance is a major problem which often occurs during anticancer chemotherapies. Photodynamic therapy (PDT) has been studied as an alternative treatment modality for drug-resistant tumors, however the question of resistance to PDT and potential cross-resistance with chemotherapy has yet to be fully answered. To investigate the mechanism of resistance to PDT, we developed an in vitro experimental model system in a mouse mammary carcinoma cell line 4T1. We used two ethylene glycol derivatives of tetraphenylporphyrin, and tetraphenylchlorin derivative, temoporfin, as photosensitizers (PS). PDT-resistant clones were obtained by exposure to a set concentration of PS followed by irradiation with increasing light doses. PDT resistance to soluble glycol porphyrins was mediated mainly by increased drug efflux through ABCB1 (P-glycoprotein) as we demonstrated by specific ABCB1 knockdown experiments, which in turn rescued the sensitivity of resistant cells to PDT. In contrast, resistance raised to temoporfin, which is generally more lipophilic than glycol porphyrins, elicited mechanism based on sequestration of the drug to lysosomes. The resistance that is acquired from a particular PS could be overcome by using a different PS, which is not susceptible to the same mechanism(s) of resistance. Elucidation of the underlying mechanisms in various types of resistance might facilitate improvements in PDT treatment design.

• MeSH
• chemorezistence genetika   MeSH
• ethylenglykoly aplikace a dávkování   chemie   MeSH
• fotochemoterapie MeSH
• fotosenzibilizující látky aplikace a dávkování   chemie   MeSH
• genový knockdown MeSH
• glykoly chemie   MeSH
• lidé MeSH
• mesoporfyriny aplikace a dávkování   chemie   MeSH
• MFC-7 buňky MeSH
• myši MeSH
• nádory mléčné žlázy u zvířat farmakoterapie   genetika   patologie   MeSH
• P-glykoprotein genetika   MeSH
• paclitaxel škodlivé účinky   MeSH
• porfyriny aplikace a dávkování   chemie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ethylenglykoly MeSH
• fotosenzibilizující látky MeSH
• glykoly MeSH
• mesoporfyriny MeSH
• P-glykoprotein MeSH
• paclitaxel MeSH
• porfyriny MeSH
• temoporfin MeSH Prohlížeč

Saturated stearic acid (SA) induces apoptosis in the human pancreatic β-cells NES2Y. However, the molecular mechanisms involved are unclear. We showed that apoptosis-inducing concentrations of SA activate the p38 MAPK signaling pathway in these cells. Therefore, we tested the role of p38 MAPK signaling pathway activation in apoptosis induction by SA in NES2Y cells. Crosstalk between p38 MAPK pathway activation and accompanying ERK pathway inhibition after SA application was also tested. The inhibition of p38 MAPK expression by siRNA silencing resulted in a decrease in MAPKAPK-2 activation after SA application, but it had no significant effect on cell viability or the level of phosphorylated ERK pathway members. The inhibition of p38 MAPK activity by the specific inhibitor SB202190 resulted in inhibition of MAPKAPK-2 activation and noticeable activation of ERK pathway members after SA treatment but in no significant effect on cell viability. p38 MAPK overexpression by plasmid transfection produced an increase in MAPKAPK-2 activation after SA exposure but no significant influence on cell viability or ERK pathway activation. The activation of p38 MAPK by the specific activator anisomycin resulted in significant activation of MAPKAPK-2. Concerning the effect on cell viability, application of the activator led to apoptosis induction similar to application of SA (PARP cleavage and caspase-7, -8, and -9 activation) and in inhibition of ERK pathway members. We demonstrated that apoptosis-inducing concentrations of SA activate the p38 MAPK signaling pathway and that this activation could be involved in apoptosis induction by SA in the human pancreatic β-cells NES2Y. However, this involvement does not seem to play a key role. Crosstalk between p38 MAPK pathway activation and ERK pathway inhibition in NES2Y cells seems likely. Thus, the ERK pathway inhibition by p38 MAPK activation does not also seem to be essential for SA-induced apoptosis.

• Klíčová slova
• ERK, NES2Y, apoptosis, fatty acids, p38 MAPK, pancreatic β-cells,
• MeSH
• aktivace enzymů MeSH
• apoptóza * účinky léků   MeSH
• beta-buňky účinky léků   metabolismus   MeSH
• buněčné linie MeSH
• exprese genu MeSH
• inhibitory proteinkinas farmakologie   MeSH
• kyseliny stearové farmakologie   MeSH
• lidé MeSH
• MAP kinasový signální systém účinky léků   MeSH
• mastné kyseliny metabolismus   farmakologie   MeSH
• mitogenem aktivované proteinkinasy p38 antagonisté a inhibitory   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• inhibitory proteinkinas MeSH
• kyseliny stearové MeSH
• mastné kyseliny MeSH
• mitogenem aktivované proteinkinasy p38 MeSH
• stearic acid MeSH Prohlížeč

BACKGROUND: In previous study we showed that caspase-2 plays the role of an apical caspase in cell death induction by taxanes in breast cancer cells. This study deals with the role of other caspases. We tested breast cancer cell lines SK-BR-3 (functional caspase-3) and MCF-7 (nonfunctional caspase-3). METHODS AND RESULTS: Using western blot analysis we demonstrated the activation of initiator caspase-8 and -9 as well as executioner caspase-6 and -7 in both tested cell lines after application of taxanes (paclitaxel, SB-T-1216) at death-inducing concentrations. Caspase-3 activation was also found in SK-BR-3 cells. Employing specific siRNAs after taxane application, suppression of caspase-3 expression significantly increased the number of surviving SK-BR-3 cells. Inhibition of caspase-7 expression also increased the number of surviving SK-BR-3 and MCF-7 cells. On the other hand, suppression of caspase-8 and caspase-9 expression had no significant effect on cell survival. However, caspase-9 seemed to be involved in the activation of caspase-3 and caspase-7. Caspase-3 and caspase-7 appeared to activate mutually. Furthermore, we observed a significant decrease in mitochondrial membrane potential (flow cytometric analysis) and cytochrome c release (confocal microscopy, western blot after cell fractionation) from mitochondria in SK-BR-3 cells. No such changes were observed in MCF-7 cells after taxane treatment. CONCLUSION: We conclude that the activation of apical caspase-2 results in the activation of caspase-3 and -7 without the involvement of mitochondria. Caspase-9 can be activated directly via caspase-2 or alternatively after cytochrome c release from mitochondria. Subsequently, caspase-9 activation can also lead to caspase-3 and -7 activations. Caspase-3 and caspase-7 activate mutually. It seems that there is also a parallel pathway involving mitochondria that can cooperate in taxane-induced cell death in breast cancer cells.

• Klíčová slova
• Breast cancer, Caspases, Cell death, Taxanes,
• Publikační typ
• časopisecké články MeSH

It has been shown in previous studies that liver HEP-G2 cells (human hepatocellular carcinoma) lose their ability to express active alcohol dehydrogenase (ADH) and cytochrome P450 2E1 (CYP2E1). Although both are ethanol-inducible enzymes, short-term exposure to ethanol does not cause any changes in expression or activity in cultured HEP-G2 cells. Therefore, we tested the effect of long-term exposure to ethanol on the expression and activity of both ADH and CYP2E1 in these cells. The expression of ADH and CYP2E1 was assessed at the mRNA and/or protein level using real-time PCR and Western blot analysis. Specific colorimetric assays were used for the measurement of ADH and CYP2E1 enzymatic activities. Caco-2 cells (active CYP2E1 and inactive ADH) were used as control cells. Significantly increased protein expression of ADH (about 2.5-fold) as well as CYP2E1 (about 1.6-fold) was found in HEP-G2 cells after long-term (12 mo) exposure to ethanol. The activity of ADH and CYP2E1 was also significantly increased from 12 ± 3 and 6 ± 1 nmol/h/mg of total protein to 191 ± 9 and 57 ± 9 nmol/h/mg of total protein, respectively. We suggest that the loss of activity of ethanol-metabolizing enzymes in cultured HEP-G2 cells is reversible and can be induced by prolonged exposure to ethanol. We are therefore able to reactivate HEP-G2 cells metabolic functions concerning ethanol oxidation just by modification of in vitro culture conditions without necessity of transfection with its side effect - enzyme overexpression.

• MeSH
• alkoholdehydrogenasa biosyntéza   genetika   MeSH
• apoptóza účinky léků   MeSH
• buňky Hep G2 MeSH
• cytochrom P-450 CYP2E1 biosyntéza   genetika   MeSH
• enzymová indukce účinky léků   MeSH
• ethanol farmakologie   MeSH
• hepatocelulární karcinom enzymologie   patologie   MeSH
• játra účinky léků   enzymologie   MeSH
• lidé MeSH
• nádory jater enzymologie   patologie   MeSH
• oxidace-redukce účinky léků   MeSH
• regulace genové exprese u nádorů účinky léků   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alkoholdehydrogenasa MeSH
• cytochrom P-450 CYP2E1 MeSH
• ethanol MeSH

The aim of this study is to compare the effects of new fluorinated taxanes SB-T-12851, SB-T-12852, SB-T-12853, and SB-T-12854 with those of the classical taxane paclitaxel and novel non-fluorinated taxane SB-T-1216 on cancer cells. Paclitaxel-sensitive MDA-MB-435 and paclitaxel-resistant NCI/ADR-RES human cancer cell lines were used. Cell growth and survival evaluation, colorimetric assessment of caspases activities, flow cytometric analyses of the cell cycle and the assessment of mitochondrial membrane potential, reactive oxygen species (ROS) and the release of cytochrome c from mitochondria were employed. Fluorinated taxanes have similar effects on cell growth and survival. For MDA-MB-435 cells, the C(50) of SB-T-12851, SB-T-12852, SB-T-12853 and SB-T-12854 was 3 nM, 4 nM, 3 nM and 5 nM, respectively. For NCI/ADR-RES cells, the C(50) of SB-T-12851, SB-T-12852, SB-T-12853, and SB-T-12854 was 20 nM, 20 nM, 10 nM and 10 nM, respectively. Selected fluorinated taxanes, SB-T-12853 and SB-T-12854, at the death-inducing concentrations (30 nM for MDA-MB-435 and 300 nM for NCI/ADR-RES) were shown to activate significantly caspase-3, caspase-9, caspase-2 and also slightly caspase-8. Cell death was associated with significant accumulation of cells in the G(2)/M phase. Cytochrome c was not released from mitochondria and other mitochondrial functions were not significantly impaired. The new fluorinated taxanes appear to use the same or similar mechanisms of cell death induction as compared with SB-T-1216 and paclitaxel. New fluorinated and non-fluorinated taxanes are more effective against drug-resistant cancer cells than paclitaxel. Therefore, new generation of taxanes, either non-fluorinated or fluorinated, are excellent candidates for further and detailed studies.

• MeSH
• buněčná smrt účinky léků   MeSH
• buněčný cyklus účinky léků   MeSH
• chemorezistence účinky léků   MeSH
• cytochromy c metabolismus   MeSH
• DNA nádorová metabolismus   MeSH
• kaspasy metabolismus   MeSH
• lidé MeSH
• mitochondrie účinky léků   metabolismus   MeSH
• nádorové buněčné linie MeSH
• paclitaxel chemie   farmakologie   MeSH
• proliferace buněk účinky léků   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• screeningové testy protinádorových léčiv MeSH
• sloučeniny fluoru chemie   farmakologie   MeSH
• taxoidy chemie   farmakologie   MeSH
• viabilita buněk účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• cytochromy c MeSH
• DNA nádorová MeSH
• kaspasy MeSH
• paclitaxel MeSH
• reaktivní formy kyslíku MeSH
• sloučeniny fluoru MeSH
• taxoidy MeSH

BACKGROUND: In this study, the effect of novel taxane SB-T-1216 and paclitaxel on sensitive MDA-MB-435 and resistant NCI/ADR-RES human breast cancer cells was compared. MATERIALS AND METHODS: Cell growth and survival were evaluated after 96-hour incubation with tested concentrations of taxanes. The effect on the formation of microtubule bundles was assessed employing fluorescence microscopy and on the cell cycle employing flow cytometric analysis. The activity of caspases was assessed employing commercial colorimetric kits. RESULTS: The IC(50) (concentration resulting in 50% of living cells in comparison with the control) of SB-T-1216 in sensitive cells was 0.6 nM versus 1 nM for paclitaxel. However, the IC(50) of SB-T-1216 in resistant cells was 1.8 nM versus 300 nM for paclitaxel. Both SB-T-1216 and paclitaxel at death-inducing concentrations induced the formation of microtubule bundles in sensitive as well as resistant cells. Cell death induced in sensitive and resistant cells by paclitaxel was associated with the accumulation of cells in the G(2)/M phase. On the contrary, cell death induced by SB-T-1216 took place without the accumulation of cells in the G(2)/M phase but with a decreased number of G(1) cells and the accumulation of hypodiploid cells. Both SB-T-1216 and paclitaxel activated caspase-3, caspase-9, caspase-2 and caspase-8 in sensitive as well as resistant cells. CONCLUSION: Cell death induced by both paclitaxel and novel taxane SB-T-1216 in breast cancer cells is associated with caspase activation and with the formation of interphase microtubule bundles. Novel taxane SB-T-1216, but not paclitaxel, seems to be capable of inducing cell death without the accumulation of cells in the G(2)/M phase.

• MeSH
• apoptóza účinky léků   MeSH
• buněčné dělení účinky léků   MeSH
• chemorezistence MeSH
• doxorubicin farmakologie   MeSH
• fluorescenční mikroskopie MeSH
• fytogenní protinádorové látky farmakologie   MeSH
• G1 fáze účinky léků   MeSH
• G2 fáze účinky léků   MeSH
• kaspasa 2 metabolismus   MeSH
• kaspasa 3 metabolismus   MeSH
• kaspasa 8 metabolismus   MeSH
• kaspasa 9 metabolismus   MeSH
• lidé MeSH
• mikrotubuly účinky léků   MeSH
• nádorové buněčné linie MeSH
• nádory prsu farmakoterapie   metabolismus   patologie   MeSH
• paclitaxel farmakologie   MeSH
• proliferace buněk účinky léků   MeSH
• protinádorová antibiotika farmakologie   MeSH
• taxoidy farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• srovnávací studie MeSH
• Názvy látek
• doxorubicin MeSH
• fytogenní protinádorové látky MeSH
• kaspasa 2 MeSH
• kaspasa 3 MeSH
• kaspasa 8 MeSH
• kaspasa 9 MeSH
• paclitaxel MeSH
• protinádorová antibiotika MeSH
• taxoidy MeSH

We studied the effect of iron deficiency, i.e., 24-h preincubation in iron-free medium, and the effect of high level of non-transferrin iron, i.e., the preincubation in ferric citrate medium containing 500 microM ferric citrate, on the expression of DMT1, Dcytb, ferroportin, hephaestin, and ceruloplasmin in various functional types of human cells. The expression of these proteins potentially involved in non-transferrin iron transport across cell membranes was tested on mRNA level by quantitative real-time PCR as well as on protein level by western blot analysis in Caco-2 (colorectal carcinoma), K562 (erythroleukemia), and HEP-G2 (hepatocellular carcinoma) cells. We found that changes in non-transferrin iron availability, i.e., iron deficiency and high level of non-transferrin iron, affect the expression of tested proteins in a cell type-specific manner. We also demonstrated that changes in the expression on mRNA level do not often correlate with relevant changes on protein level.

• MeSH
• buněčná membrána metabolismus   MeSH
• buněčné linie MeSH
• ceruloplasmin genetika   metabolismus   MeSH
• cytochromy typu b genetika   metabolismus   MeSH
• exprese genu * MeSH
• ferroportin MeSH
• kultivační média chemie   MeSH
• lidé MeSH
• membránové proteiny * genetika   metabolismus   MeSH
• oxidoreduktasy genetika   metabolismus   MeSH
• proteiny přenášející kationty genetika   metabolismus   MeSH
• transferin metabolismus   MeSH
• železo metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ceruloplasmin MeSH
• CYBRD1 protein, human MeSH Prohlížeč
• cytochromy typu b MeSH
• ferroportin MeSH
• HEPH protein, human MeSH Prohlížeč
• kultivační média MeSH
• membránové proteiny * MeSH
• oxidoreduktasy MeSH
• proteiny přenášející kationty MeSH
• solute carrier family 11- (proton-coupled divalent metal ion transporters), member 2 MeSH Prohlížeč
• transferin MeSH
• železo MeSH