For this purpose, we investigated ARH77 cells that had shown the

For this purpose, we investigated ARH77 cells that had shown the highest TXNIP Selleck RXDX-101 RNA level response compared to the unresponsive MC/CAR cells (Figure 1A). As expected, phloretin blocked the hyperglycemia effect on TXNIP RNA level (1.5 ± 0.05 vs. 1.03 ± 0.03, p < 0.01) (Figure 4A) and significantly reduced ROS (2.1 ± 0.08 vs 1.84 ± 0.14, p < 0.05) in ARH77 cells (Figure 4B). The addition of phloretin had no effect on either TXNIP or ROS levels in the MC/CAR cells (Figure 4A, B). This confirmed that glucose played a major role in the TXNIP RNA regulation in responsive

cells ARH77. Figure 4 A. Blocking glucose transport blocks the hyperglycemia effect oon thioredoxin-interacting protein (TXNIP) RNA levels. Cells were grown in 5 mM glucose or 20 selleck mM chronically.. For glucose uptake inhibition, phlor (200 μM) was added to 20 mM media and cells AZD6244 price harvested after 24 hours. Fold change is based on comparison to 5 mM glucose. B. Reactive oxygen species (ROS)-levels in response to phlor pre-treatment. Cells were treated as in A. ROS levels were measured as mean fluorescence

of 50,000 cells and compared to 5 mM as baseline. Hyperglycemia increases the DEX-IC50 in MM cells At this point our data were suggesting that DEX and glucose together reduced ROS production in ARH77, NCIH929 and MC/CAR cells independently from the TXNIP-TRX regulation. Paradoxically, DEX + glucose further decreased ROS level by increasing TRX activity in MC/CAR cells. It seemed that DEX was mitigating the oxidative stress and ROS production

induced by glucose in those cells independently from TXNIP expression. We then decided to test the hypothesis of TXNIP-independent effect by assessing the cytotoxicity of DEX in TXNIP-glucose/DEX responsive cells ARH77 and TXNIP-glucose/DEX unresponsive cells MC/CAR. When the dose response effect to DEX was evaluated in ARH77 and MC/CAR cells in 20 mM glucose, we found that hyperglycemia increased the IC50 for both cell lines by a factor of 10 (ARH77: 48 μM to 510 μM; MC/CAR 36 μM to 303 μM) (Figure 5). These data suggest that MM cells were more resistant to DEX in conditions of hyperglycemia, probably because of the hampering effect of DEX on ROS production as shown in Figure 2. Figure 5 Hyperglycemia increase the DEX-IC 50 in MM cells . Cells were grown in 5 or 20 mM glucose chronically. Dexamethasone, in varying concentrations, was added for 24 hour after which cells were harvested. IC50 was calculated using Calcusyn software and represented as median dose response. A. ARH77 response B. MC/CAR response. Discussion Our study addresses the response of cancerous cells in conditions of hyperglycemia either related to drug induction or underlining diabetes.

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