ABSTRACT
Background and purpose: Non-homologous end joining [NHEJ] is the major pathway for removing DNA double strand breaks lesions. NHEJ is considered to be a resistant factor against chemotherapy induced neuropathy. beta-Lapachone [beta-Lap] is one of the antineoplastic agents which is shown to have anti neuroinflammatory effects. Extremely low frequency [<300 Hz] electromagnetic field [EMF] is shown to decrease NHEJ genes expression. Morphine [Mor] is associated with reducing effect on DNA repair and induce DNA damages. The goal of this study was to evaluate the effect of combination treatment of beta-Lap, morphine [Mor] and EMF on expression of NHEJ related genes [XRCC4, Ku70, Ku80, DNA-PKcs and LIG4]
Materials and methods: SH-SY5Y cells [epithelial neuroblasts] were treated with four combinational treatments of beta-Lap [2.0 and 3.2 microM], Mor [5.0 microM] and EMF [50 Hz, 0.50 mT, "15 min field on/15 min field off"] and mRNA levels of XRCC4, Ku70, Ku80, DNA-PKcs and LIG4 were evaluated by quantitative real-time PCR and primers specific for the examined genes. The experiments were done in triplicates
Results: No significant alteration in the mRNA levels of NHEJ related genes was observed in "beta-Lap alone" and "beta-Lap + Mor" treated cells. The expression levels of NHEJ related genes were significantly increased in "beta-Lap + EMF" and "beta-Lap + Mor + EMF". Multiple linear regression analysis showed that the effect of EMF and Mor on NHEJ related genes expression is opposite to the effect of beta-Lap
Conclusion: In overall, combination of beta-Lap, Mor and EMF leads to increased expression of NHEJ related gene expression. This effect may lead to decreased sensitivity of SH-SY5Y cells against beta-Lap and can improve its neuroprotective property which might be hopeful for its clinical applications