γ-Tocotrienol Prevents Oxidative Stress-Induced Telomere Shortening in Human Fibroblasts Derived from Different Aged Individuals

Suzana Makpol,Azrina Zainal Abidin,Wan Zurinah Wan Ngah,Musalmah Mazlan,Gapor Md Top,Khalilah Sairin

doi:10.4161/oxim.3.1.9940

Suzana Makpol, Azrina Zainal Abidin + Show 4 more

Open Access

https://doi.org/10.4161/oxim.3.1.9940

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Abstract

The effects of palm gamma-tocotrienol (GGT) on oxidative stress-induced cellular ageing was investigated in normal human skin fibroblast cell lines derived from different age groups; young (21-year-old, YF), middle (40-year-old, MF) and old (68-year-old, OF). Fibroblast cells were treated with gamma-tocotrienol for 24 hours before or after incubation with IC50 dose of H2O2 for 2 hours. Changes in cell viability, telomere length and telomerase activity were assessed using the MTS assay (Promega, USA), Southern blot analysis and telomere repeat amplification protocol respectively. Results showed that treatment with different concentrations of gamma-tocotrienol increased fibroblasts viability with optimum dose of 80 microM for YF and 40 microM for both MF and OF. At higher concentrations, gamma-tocotrienol treatment caused marked decrease in cell viability with IC50 value of 200 microM (YF), 300 microM (MF) and 100 microM (OF). Exposure to H2O2 decreased cell viability in dose dependent manner, shortened telomere length and reduced telomerase activity in all age groups. The IC50 of H2O2 was found to be; YF (700 microM), MF (400 microM) and OF (100 microM). Results showed that viability increased significantly (p < 0.05) when cells were treated with 80 microM and 40 microM gamma-tocotrienol prior or after H2O2-induced oxidative stress in all age groups. In YF and OF, pretreatment with gamma-tocotrienol prevented shortening of telomere length and reduction in telomerase activity. In MF, telomerase activity increased while no changes in telomere length was observed. However, post-treatment of gamma-tocotrienol did not exert any significant effects on telomere length and telomerase activity. Thus, these data suggest that gamma-tocotrienol protects against oxidative stress-induced cellular ageing by modulating the telomere length possibly via telomerase.

Highlights

Normal human cells exhibit a limited capacity for proliferation in culture and this finite replicative lifespan has frequently been used as a model of human aging in mitotic tissues and organs.[1]
The objective of this study was to determine the protective effects of palm γ-tocotrienol treatment before or after hydrogen peroxide (H2O2)-induced oxidative stress on cell viability, telomere length and telomerase activity in normal human skin fibroblast cell lines derived from different age groups viz; young (21-yearold), middle (40-year-old) and old (68-year-old)
Treatment of fibroblasts with inhibitory concentration (IC50) dose of H2O2 resulted in 50% reduction in cell viability (Fig. 4)

Summary

Introduction

Normal human cells exhibit a limited capacity for proliferation in culture and this finite replicative lifespan has frequently been used as a model of human aging in mitotic tissues and organs.[1]. In normal human somatic cells, because of inherent limitations in the mechanics of DNA replication, telomeres shorten at each cell division. In the absence of telomerase, when telomere shortening reaches a critical limit, cells are susceptible to chromosomal aberrations such as end-to-end fusion and aneuploidy. In such a situation, the cells cease to divide and reach replicative senescence.[5,6] Telomere length may restrict the replicative potential of hemopoietic cells contributing to the decline in immune function with age.[7] The erosion of chromosome ends, or telomeres, was proposed as a major mechanism that contributes to cellular aging.[8]

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