Silencing of Peroxiredoxin-4 in Anticancer Activity of Gamma-Tocotrienol

Peroxiredoxin-4 (PRDX4) is known to have a role in protecting cells from oxidative stress. It has been previously reported to increase in HepG2 liver cancer cells treated with gamma-tocotrienol (GTT). As GTT treatment potentially kills the cancer cell by regulating multiple signaling pathways, this study aims to determine the involvement of PRDX4 in GTT anticancer activity by silencing the PRDX4 gene. The efficiency of PRDX4 silencing is achieved by optimizing HepG2 cell density, effect of serum presence in transduction media, incubation time of the cells with lentivirus, polybrene concentration, puromycin dose, functional titer, and multiplicity of infection (MOI) of the lentivirus. Silenced HepG2-PRDX4 cells (HepG2-shRNA-PRDX4) were treated with 70 μ M of GTT for 48 h. GTT treatment significantly decreased the HepG2-shRNA-PRDX4 cell viability, increased apoptosis rate, and reduced free radical production compared to untreated HepG2-shRNA-PRDX4 cells. These findings are further supported by proteomic analysis, which showed that pro-apoptotic and DNA damage proteins were upregulated, and proteins involved in cell cycle arrest, carcinogenesis, and anti-apoptotic signaling pathways were downregulated in HepG2-shRNA-PRDX4 cells treated with GTT compared to control. In conclusion, PRDX4 plays a role in GTT anticancer activity by increasing free radical production and oxidative damage to induce apoptosis in HepG2 cell.