Response to dexamethasone is glucose-sensitive in multiple myeloma cell lines

<p>Abstract</p> <p>Background</p> <p>Hyperglycemia is among the major side effects of dexamethasone (DEX). Glucose or glucocorticoid (GC) regulates the expression of thioredoxin-interacting protein (TXNIP) that controls the production of reactive oxygen species (ROS) through the modulation of thioredoxin (TRX) activity.</p> <p>Methods</p> <p>Multiple myeloma (MM) cells were grown in 5 or 20 mM/L glucose with or without 25 μM DEX. Semiquantitative reverse transcription-PCR (RT-PCR) was used to assess TXNIP RNA expression in response to glucose and DEX. ROS were detected by 5-6-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H2DCFDA). TRX activity was assayed by the insulin disulfide-reducing assay. Proliferation was evaluated using CellTiter96 reagent with 490-nm absorbtion and used to calculate the DEX IC₅₀in 20 mM/L glucose using the Chou's dose effect equation.</p> <p>Results</p> <p>TXNIP RNA level responded to glucose or DEX with the same order of magnitude ARH77 > NCIH929 > U266B1 in these cells. MC/CAR cells were resistant to the regulation. ROS level increased concurrently with reduced TRX activity. Surprisingly glucose increased TRX activity in MC/CAR cells keeping ROS level low. DEX and glucose were lacking the expected additive effect on TXNIP RNA regulation when used concurrently in sensitive cells. ROS level was significantly lower when DEX was used in conditions of hyperglycemia in ARH77/NCIH9292 cells but not in U266B1 cells. Dex-IC₅₀increased 10-fold when the dose response effect of DEX was evaluated with glucose in ARH && and MC/Car cells</p> <p>Conclusions</p> <p>Our study shows for the first time that glucose or DEX regulates important components of ROS production through TXNIP modulation or direct interference with TRX activity in MM cells. We show that glucose modulates the activity of DEX through ROS regualtion in MM cells. A better understanding of these pathways may help in improving the efficacy and reducing the toxicity of DEX, a drug still highly used in the treatment of MM. Our study also set the ground to study the relevance of the metabolic milieu in affecting drug response and toxicity in diabetic versus non-diabetic patients with MM.</p

The histone deacetylase inhibitor cambinol prevents acidic pHe-induced anterograde lysosome trafficking independently of sirtuin activity

AbstractCommon features of the solid tumor microenvironment, such as acidic extracellular pH and growth factors, are known to induce the redistribution of lysosomes from a perinuclear region to a position near the plasma membrane. Lysosome/plasma membrane juxtaposition facilitates invasion by allowing for the release of lysosomal proteases, including cathepsin B, which contribute to matrix degradation. In this study we identified the sirtuin 1/sirtuin 2 (SIRT1/2) inhibitor cambinol acts as a drug that inhibits lysosome redistribution and tumor invasion. Treatment of cells with cambinol resulted in a juxtanuclear lysosome aggregation (JLA) similar to that seen upon treatment with the PPARγ agonist, troglitazone (Tro). Like Tro, cambinol required the activity of ERK1/2 in order to induce this lysosome clustering phenotype. However, cambinol did not require the activity of Rab7, suggesting that this drug causes JLA by a mechanism different from what is known for Tro. Additionally, cambinol-induced JLA was not a result of autophagy induction. Further investigation revealed that cambinol triggered JLA independently of its activity as a SIRT1/2 inhibitor, suggesting that this drug could have effects in addition to SIRT1/2 inhibition that could be developed into a novel anti-cancer therapy

Hyperglycemia regulates thioredoxin-ROS activity through induction of thioredoxin-interacting protein (TXNIP) in metastatic breast cancer-derived cells MDA-MB-231

<p>Abstract</p> <p>Background</p> <p>We studied the RNA expression of the genes in response to glucose from 5 mM (condition of normoglycemia) to 20 mM (condition of hyperglycemia/diabetes) by microarray analysis in breast cancer derived cell line MDA-MB-231. We identified the thioredoxin-interacting protein (TXNIP), whose RNA level increased as a gene product particularly sensitive to the variation of the level of glucose in culture media. We investigated the kinesis of the TXNIP RNA and protein in response to glucose and the relationship between this protein and the related thioredoxin (TRX) in regulating the level of reactive oxygen species (ROS) in MDA-MB-231 cells.</p> <p>Methods</p> <p>MDA-MB-231 cells were grown either in 5 or 20 mM glucose chronically prior to plating. For glucose shift (5/20), cells were plated in 5 mM glucose and shifted to 20 mM at time 0. Cells were analyzed with Affymetrix Human U133A microarray chip and gene expression profile was obtained. Semi-quantitative RT-PCR and Western blot was used to validate the expression of TXNIP RNA and protein in response to glucose, respectively. ROS were detected by CM-H2DCFDA (5–6-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate) and measured for mean fluorescence intensity with flow cytometry. TRX activity was assayed by the insulin disulfide reducing assay.</p> <p>Results</p> <p>We found that the regulation of TXNIP gene expression by glucose in MDA-MB-231 cells occurs rapidly within 6 h of its increased level (20 mM glucose) and persists through the duration of the conditions of hyperglycemia. The increased level of TXNIP RNA is followed by increased level of protein that is associated with increasing levels of ROS and reduced TRX activity. The inhibition of the glucose transporter GLUT1 by phloretin notably reduces TXNIP RNA level and the inhibition of the p38 MAP kinase activity by SB203580 reverses the effects of TXNIP on ROS-TRX activity.</p> <p>Conclusion</p> <p>In this study we show that TXNIP is an oxidative stress responsive gene and its expression is exquisitely regulated by glucose level in highly metastatic MDA-MB-231 cells.</p

A) MDA-MB-231 cells were grown either in 5 or 20 mM glucose chronically prior to plating

<p><b>Copyright information:</b></p><p>Taken from "Hyperglycemia regulates thioredoxin-ROS activity through induction of thioredoxin-interacting protein (TXNIP) in metastatic breast cancer-derived cells MDA-MB-231"</p><p>http://www.biomedcentral.com/1471-2407/7/96</p><p>BMC Cancer 2007;7():96-96.</p><p>Published online 7 Jun 2007</p><p>PMCID:PMC1906826.</p><p></p> For glucose shift (5/20), cells were plated in 5 mM glucose and shifted to 20 mM at time 0. Cells were harvested at 12 h based on previous growth curves obtained at specified glucose concentration and RNA was isolated, labeled and hybridized to Affymetrix Human U133A microarray chip. Average derived from duplictaes is shown as relative expression of TXNIP and TRX RNAs, respectively. B) TXNIP and TRX RNA message levels were detected by semi-quantitative PCR in MDA-MB-231 cells grown in the same conditions as in A. Average relative levels as compared to control β-actin RNA of TXNIP and TRX RNA messages from duplicates are represented. Representative gel electrophoresis of PCR products obtained from duplicate experiments is shown in the inset

A) TXNIP RNA message levels were detected by semi-quantitative PCR in MDA-MB-231 cells grown either in 5 or 20 mM glucose chronically prior to plating

<p><b>Copyright information:</b></p><p>Taken from "Hyperglycemia regulates thioredoxin-ROS activity through induction of thioredoxin-interacting protein (TXNIP) in metastatic breast cancer-derived cells MDA-MB-231"</p><p>http://www.biomedcentral.com/1471-2407/7/96</p><p>BMC Cancer 2007;7():96-96.</p><p>Published online 7 Jun 2007</p><p>PMCID:PMC1906826.</p><p></p> Average relative levels as compared to control β-actin RNA of TXNIP and TRX RNA messages from triplicates are represented. For inhibition of the p38 MAP kinase cells grown at 20 mM were pre-treated for 24 h with 20 μM SB203580. B) MDA-MB-231 cells were grown either in 5 or 20 mM glucose chronically prior to plating. Cells were assessed for ROS levels by DCFDA fluorescence staining and flow cytometry as shown in the inlet. For inhibition of the p38 MAP kinase cells grown at 20 mM glucose were treated for 24 h with 20 μM SB203580. Average mean fluorescence from triplicates is expressed per each group of cells. B) MDA-MB-231 cells were grown either in 5 or 20 mM glucose chronically prior to plating. Cells were assessed for TRX activity by the insulin disulfide reducing assay as described and the average OD 410 readings from triplicates are shown for each group of cells. For inhibition of the p38 MAP kinase cells grown at 20 mM were pre-treated for 24 h with 20 μM SB203580

Prenatal exposure to the probiotic Lactococcus lactis decreases anxiety-like behavior and modulates cortical cytoarchitecture in a sex specific manner.

Development of the cerebral cortex may be influenced by the composition of the maternal gut microbiota. To test this possibility, we administered probiotic Lactococcus lactis in drinking water to mouse dams from day 10.5 of gestation until pups reached postnatal day 1 (P1). Pups were assessed in a battery of behavioral tests starting at 10 weeks old. We found that females, but not males, exposed to probiotic during prenatal development spent more time in the center of the open field and displayed decreased freezing time in cue associated learning, compared to controls. Furthermore, we found that probiotic exposure changed the density of cortical neurons and increased the density of blood vessels in the cortical plate of P1 pups. Sex-specific differences were observed in the number of mitotic neural progenitor cells, which were increased in probiotic exposed female pups. In addition, we found that probiotic treatment in the latter half of pregnancy significantly increased plasma oxytocin levels in mouse dams, but not in the offspring. These results suggest that exposure of naïve, unstressed dams to probiotic may exert sex-specific long-term effects on cortical development and anxiety related behavior in the offspring