High-Dose Acetaminophen Inhibits the Lethal Effect of Doxorubicin in HepG2 Cells: The Role of P-glycoprotein and Mitogen-Activated Protein Kinase p44/42 Pathway

Abstract

Doxorubicin (DOX) is a widely used chemotherapeutic drug for human hepatocellular carcinoma (HCC). A major limitation to its effectiveness is the development of multidrug resistance of cancer cells. In clinical trials, patients with advanced HCC were treated with high-dose acetaminophen (HAAP) in an effort to improve the antitumor activity of chemotherapeutics. In this study, we investigated the effect of concomitant treatment of DOX and HAAP on hepatoma-derived HepG2 cells. Viability, cell cycle distribution, and ultrastructure were examined. Unexpectedly, HAAP, when added to DOX-exposed cells, increased cell viability, released cell cycle arrest, and decreased apoptosis. To elucidate the mechanisms by which HAAP reduces the DOX lethal effect to HepG2 cells, we investigated the multidrug resistance P-glycoprotein (P-gp) and p44/42-mitogen-activated protein kinase (MAPK) pathways. The P-gp function was enhanced by DOX and HAAP, and it was further stimulated during combined treatment, leading to decreased DOX retention. Verapamil (VRP), when added to DOX ϩ HAAP exposure, increased DOX accumulation and restored DOXinduced toxicity. The increased phospho-p44/42-MAPK level in DOX-exposed cells was inhibited by HAAP. In addition, suppression of p44/42 activation by the p44/42-MAPK inhibitor 2Ј-amino-3Ј-methoxyflavone (PD98059) blocked DOX-induced apoptosis. These findings suggest that the antagonistic effect of concomitant DOX ϩ HAAP treatment occurs as a result of interactive stimulation of P-gp, generating decreased intracellular drug concentrations. Furthermore, inhibition of the p44/ 42-MAPK phosphorylation by HAAP could abolish the DOXinduced cell death pathway. Thus, combined treatment by DOX ϩ HAAP, intended to improve chemotherapeutic efficacy, could have an opposite effect facilitating cancer cell survival.

The Effect of Doxorubicin on MEK-ERK Signaling Predicts Its Efficacy in HCC

“…DNA damaging agents besides DOX, such as etoposide, ionizing radiation, and ultraviolet irradiation also demonstrated similar effects on ERK activation [18,22]. The role of sustained ERK activation in causing cell cycle arrest and apoptosis was confirmed by adding PD98059 or U0126 to DOX and showing that the DOX effects were attenuated by inhibiting MEK-ERK activation in HepG2 and other cell types [18,19,22]. In contrast, we observed that the U0126/DOX combination was more effective at inhibiting cell growth and inducing apoptosis than the single agents in HepG2 cells.…”

Dual role of acetaminophen in promoting hepatoma cell apoptosis and kidney fibroblast proliferation

“…In addition, APAP can enhance the chemotherapeutic anticancer effects of drugs used to treat neuroblastoma, leukemia and ovarian carcinoma (30,34,35). According to the above studies, APAP can activate different cytotoxic mechanisms in liver, kidney and tumor cells (14,19,21,31,36). To date, most studies have focused on the mechanisms of APAP-induced cytotoxicity and on how to prevent high-dose APAP-related poisoning of the liver and the kidneys.…”

Effect of Doxorubicin on Histomorphology of Liver of Wistar Albino Rats

“…A major limitation to its effect is the development of multi drug resistance of cancer cells [8]. Histopathological changes such as necrosis, hepatocyte degeneration, sinusoidal dilatation, haemorrhage and vascular congestion and dilatation also occur [9].…”