Comparative effect of vitamin E compounds on HSP70 expression in response to acute redox imbalance in Chang liver cells

Abstract Background: HSP70 represents the most highly induced member of the stress protein family which is constitutively expressed in normal cell conditions as chaperon and rapidly upregulated in response to stress conditions. Vitamin E compounds are considered to be the most potent oxidation chain breaking compounds. Although α-tocopherol, has been long considered as the most potent antioxidant among the vitamin E isomers, many studies have recently suggested a higher antioxidant potency of tocotrienols compared to tocopherols. Present study was carried out to investigate the effects of tocotrienol supplementation compared to α-tocopherol on HSP70 expression.Methods: To assess whether the increase in HSP70 secondary to the stress caused by the oxidant could decrease in the presence of vitamin E; two groups of cells were incubated for 4 hours with α-tocopherol and palm tocotrienol-rich fraction respectively with concentration of 10, 20 and 30 μg/ml after the cells were pre-exposed to oxidative stress.Results: The comparison between the negative control which represents the basal expression of HSP70 and the positive control that represents the expression of HSP70 as a response to the oxidant, has clearly indicated that treatment with 100 μM copper sulphates for 24 hours resulted in a significant up-regulation of HSP70 expression. The present study has shown that the overall effect of vitamin E compounds seems to reduce the increase in HSP70 expression. α-tocopherol tended to trigger a more constant rate of response to the dose given but unable to significantly induced the decrease of the HSP70 expression as compared to tocotrienol.Conclusion: Treatment with vitamin E has conferred significant protection against stress induced cellular damage. Whether the reduction of HSP70 by vitamin E is deleterious or beneficial is still controversial and needs to be considered.