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

P-glycoprotein Mediates Resistance to the Anaplastic Lymphoma Kinase Inhiitor Ensartinib in Cancer Cells

Ensartinib (X-396) is a promising second-generation small-molecule inhibitor of anaplastic lymphoma kinase (ALK) that was developed for the treatment of ALK-positive non-small-cell lung cancer. Preclinical and clinical trial results for ensartinib showed superior efficacy and a favorable safety profile compared to the first-generation ALK inhibitors that have been approved by the U.S. Food and Drug Administration. Although the potential mechanisms of acquired resistance to ensartinib have not been reported, the inevitable emergence of resistance to ensartinib may limit its therapeutic application in cancer. In this work, we investigated the interaction of ensartinib with P-glycoprotein (P-gp) and ABCG2, two ATP-binding cassette (ABC) multidrug efflux transporters that are commonly associated with the development of multidrug resistance in cancer cells. Our results revealed that P-gp overexpression, but not expression of ABCG2, was associated with reduced cancer cell susceptibility to ensartinib. P-gp directly decreased the intracellular accumulation of ensartinib, and consequently reduced apoptosis and cytotoxicity induced by this drug. The cytotoxicity of ensartinib could be significantly reversed by treatment with the P-gp inhibitor tariquidar. In conclusion, we report that ensartinib is a substrate of P-gp, and provide evidence that this transporter plays a role in the development of ensartinib resistance. Further investigation is needed.

Polypharmacy in polymorbid pregnancies and the risk of congenital malformations-A systematic review

With an increased prevalence of concurrent morbidities during pregnancy, polypharmacy has become increasingly common in pregnant women. The risks associated with polypharmacy may exceed those of individual medication because of drug-drug interactions. This systematic review aims to evaluate the risk of congenital malformations in polymorbid pregnancies exposed to first-trimester polypharmacy. PubMed, Embase and Scopus were searched to identify original human studies with first- trimester polypharmacy due to polymorbidity as the exposure and congenital malformations as the outcome. After screening of 4034 identified records, seven studies fulfilled the inclusion criteria. Four of the seven studies reported an increased risk of congenital malformations compared with unexposed or monotherapy, odds ratios ranging from 1.1 to >10.0. Particularly, short-term anti-infective treatment combined with other drugs and P-glycoprotein substrates were associated with increased malformation risks. In conclusion, knowledge is limited on risks associated with first-trimester polypharmacy due to polymorbidity with the underlying evidence of low quantity and quality. Therefore, an increased focus on pharmacovigilance to enable safe drug use in early pregnancy is needed. Large-scale register-based studies and better knowledge of placental biology are needed to support the clinical management of polymorbid pregnancies that require polypharmacy.

Cathepsin B-Responsive Liposomes for Controlled Anticancer Drug Delivery in Hep G2 Cells

In recent decades, several types of anticancer drugs that inhibit cancer cell growth and cause cell death have been developed for chemotherapeutic application. However, these agents are usually associated with side effects resulting from nonspecific delivery, which may induce cytotoxicity in healthy cells. To reduce the nonspecific delivery issue, nanoparticles have been successfully used for the delivery of anticancer drugs to specific target sites. In this study, a functional polymeric lipid, PEG-GLFG-K(C₁₆)₂ (PEG-GLFG, polyethylene glycol-Gly-Leu-Phe-Gly-Lys(C₁₆)₂), was synthesized to enable controlled anticancer drug delivery using cathepsin B enzyme-responsive liposomes. The liposomes composed of PEG-GLFG/DOTAP (1,2-dioleoyl-3-trimethylammonium-propane (chloride salt))/DPPC (dipalmitoylphosphatidylcholine)/cholesterol were prepared and characterized at various ratios. The GLFG liposomes formed were stable liposomes and were degraded when acted upon by cathepsin B enzyme. Doxorubicin (Dox) loaded GLFG liposomes (GLFG/Dox) were observed to exert an effective anticancer effect on Hep G2 cells in vitro and inhibit cancer cell proliferation in a zebrafish model.

Acetaminophen cytotoxicity in HepG2 cells is associated with a decoupling of glycolysis from the TCA cycle, loss of NADPH production, and suppression of anabolism

Acetaminophen (APAP) is one of the most commonly used analgesics worldwide, and overdoses are associated with lactic acidosis, hepatocyte toxicity, and acute liver failure due to oxidative stress and mitochondrial dysfunction. Hepatoma cell lines typically lack the CYP450 activity to generate the reactive metabolite of APAP observed in vivo, but are still subject to APAP cytotoxicity. In this study, we employed metabolic profiling and isotope labelling approaches to investigate the metabolic impact of acute exposure to cytotoxic doses of APAP on the widely used HepG2 cell model. We found that APAP exposure leads to limited cellular death and substantial growth inhibition. Metabolically, we observed an up-regulation of glycolysis and lactate production with a concomitant reduction in carbon from glucose entering the pentose-phosphate pathway and the TCA cycle. This was accompanied by a depletion of cellular NADPH and a reduction in the de novo synthesis of fatty acids and the amino acids serine and glycine. These events were not associated with lower reduced glutathione levels and no glutathione conjugates were seen in cell extracts. Co-treatment with a specific inhibitor of the lactate/H⁺ transporter MCT1, AZD3965, led to increased apoptosis in APAP-treated cells, suggesting that lactate accumulation could be a cause of cell death in this model. In conclusion, we show that APAP toxicity in HepG2 cells is largely independent of oxidative stress, and is linked instead to a decoupling of glycolysis from the TCA cycle, lactic acidosis, reduced NADPH production, and subsequent suppression of the anabolic pathways required for rapid growth.

Doxorubicin induces apoptosis by targeting Madcam1 and AKT and inhibiting protein translation initiation in hepatocellular carcinoma cells

Doxorubicin (Doxo) is one of the most widely used chemotherapeutic drugs for patients with hepatocellular carcinoma (HCC). Doxo is a DNA intercalating drug that inhibits topoisomerase II. Thereby Doxo has the ability to block DNA replication and induce apoptosis. However, the other targets and mechanisms through which Doxo induces apoptosis to treat HCC still remain unknown. Here, we identified Mucosal vascular addressin cell adhesion molecule 1 (Madcam1) as a potential Doxo target because Madcam1 overexpression suppressed, while Madcam1 depletion stimulated Doxo-induced apoptosis. Furthermore, we first revealed that Doxo can induce apoptosis by blocking protein translation initiation. In contrast, Madcam1 activated protein translation through an opposite mechanism. We also found de-phosphorylation of AKT may be an important pro-apoptotic event that is triggered by Doxo-induced Madcam1 down-regulation. Finally, we revealed that Madcam1 promoted increased AKT phosphorylation, which is essential for maintaining the sensitivity of HCC cells to Doxo treatment. Taken together, we uncovered a potential mechanism for Doxo-induced apoptosis in HCC treatment through targeting Madcam1 and AKT and blocking protein translation initiation.

Regulation of multidrug resistance proteins by genistein in a hepatocarcinoma cell line: impact on sorafenib cytotoxicity

Hepatocellular carcinoma (HCC) is the fifth most frequent cancer worldwide. Sorafenib is the only drug available that improves the overall survival of HCC patients. P-glycoprotein (P-gp), Multidrug resistance-associated proteins 2 and 3 (MRP2 and 3) and Breast cancer resistance protein (BCRP) are efflux pumps that play a key role in cancer chemoresistance. Their modulation by dietary compounds may affect the intracellular accumulation and therapeutic efficacy of drugs that are substrates of these transporters. Genistein (GNT) is a phytoestrogen abundant in soybean that exerts its genomic effects through Estrogen-Receptors and Pregnane-X-Receptor (PXR), which are involved in the regulation of the above-mentioned transporters. We evaluated the effect of GNT on the expression and activity of P-gp, MRP2, MRP3 and BCRP in HCC-derived HepG2 cells. GNT (at 1.0 and 10 μM) increased P-gp and MRP2 protein expression and activity, correlating well with an increased resistance to sorafenib cytotoxicity as detected by the methylthiazole tetrazolium (MTT) assay. GNT induced P-gp and MRP2 mRNA expression at 10 but not at 1.0 μM concentration suggesting a different pattern of regulation depending on the concentration. Induction of both transporters by 1.0 μM GNT was prevented by cycloheximide, suggesting translational regulation. Downregulation of expression of the miR-379 by GNT could be associated with translational regulation of MRP2. Silencing of PXR abolished P-gp induction by GNT (at 1.0 and 10 μM) and MRP2 induction by GNT (only at 10 μM), suggesting partial mediation of GNT effects by PXR. Taken together, the data suggest the possibility of nutrient-drug interactions leading to enhanced chemoresistance in HCC when GNT is ingested with soy rich diets or dietary supplements.

[Interaction of anesthetics and analgesics with tumor cells]

The results of preclinical and clinical studies indicate that the perioperative period is a vulnerable period for cancer progression and metastasis. The risk of cancer cell dissemination is enhanced by the combination of surgical manipulation and perioperative immunosuppression. Whether the oncological outcome of cancer patients can be influenced by the choice of anesthetic techniques is still a matter of debate. This review summarizes the molecular characteristics of cancer and interaction of anesthetic and analgesic drugs with cancer cells.

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

Acetaminophen (APAP), is a safe analgesic and antipyretic drug at therapeutic dose, and is widely used in the clinic. However, high doses of APAP can induce hepatotoxicity and nephrotoxicity. Most studies have focused on high‑dose APAP‑induced acute liver and kidney injury. So far, few studies have investigated the effects of the therapeutic dose (1/10 of the high dose) or of the low dose (1/100 of the high dose) of APAP on the cells. The aim of this study was to investigate the cellular effects of therapeutic- or low‑dose APAP treatment on hepatoma cells and kidney fibroblasts. As expected, high‑dose APAP treatment inhibited while therapeutic and low‑dose treatment did not inhibit cell survival of kidney tubular epithelial cells. In addition, therapeutic-dose treatment induced an increase in the H2O2 level, activated the caspase‑9/‑3 cascade, and induced cell apoptosis of hepatoma cells. Notably, APAP promoted fibroblast proliferation, even at low doses. This study demonstrates that different cellular effects are exerted upon treatment with different APAP concentrations. Our results indicate that treatment with the therapeutic dose of APAP may exert an antitumor activity on hepatoma, while low‑dose treatment may be harmful for patients with fibrosis, since it may cause proliferation of fibroblasts.

Key role of nuclear factor-κB in the cellular pharmacokinetics of adriamycin in MCF-7/Adr cells: the potential mechanism for synergy with 20(S)-ginsenoside Rh2

We have previously demonstrated that ginsenoside 20(S)-Rh2 is a potent ATP-binding cassette (ABC) B1 inhibitor and explored the cellular pharmacokinetic mechanisms for its synergistic effect on the cytotoxicity of adriamycin. The present studies were conducted to elucidate the key factors that influenced ABCB1 expression, which could further alter adriamycin cellular pharmacokinetics. Meanwhile, the influence of 20(S)-Rh2 on the above factors was revealed for explaining its synergistic effect from the view of ABCB1 expression. The results indicated that 20(S)-Rh2 inhibited adriamycin-induced ABCB1 expression in MCF-7/Adr cells. Subsequent analyses indicated that 20(S)-Rh2 markedly inhibited adriamycin-induced activation of the mitogen-activated protein kinase (MAPK)/nuclear factor (NF)-κB pathway, NF-κB translocation to the nucleus, and NF-κB binding activity. Furthermore, 20(S)-Rh2 repressed the Adriamycin-enhanced ability of NF-κB to bind to the human multidrug resistance (MDR1) promoter, and MAPK/NF-κB inhibitors and NF-κB small interfering RNA reversed the adriamycin-induced expression of ABCB1. Moreover, the cellular pharmacokinetics of adriamycin was also significantly altered by inhibiting NF-κB. In conclusion, the MAPK/NF-κB pathway mediates adriamycin-induced ABCB1 expression and subsequently alters the cellular pharmacokinetics of adriamycin. It was speculated that 20(S)-Rh2 acted on this pathway to lower adriamycin-induced ABCB1 expression in MCF-7/Adr cells, which provided mechanism-based support to the development of 20(S)-Rh2 as a MDR reversal agent.

Reversal of P-glycoprotein-mediated multidrug resistance of human hepatic cancer cells by Astragaloside II

OBJECTIVES

Chemoresistance is the main obstacle encountered in cancer treatment and is frequently associated with multidrug resistance (MDR). Astragaloside is a saponin which is widely used in traditional Chinese medicine. It has been reported that Astragaloside has antitumour effects on hepatocellular carcinoma Bel-7402 cells in vitro and in vivo. The purpose of this study was to examine the effects of Astragaloside II on the reversal of MDR and its molecular mechanism in vitro.

METHODS

In this study, Bel-7402 and Bel-7402/FU cell lines were used as the experimental model. Drug sensitivity was determined using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, accumulation and efflux of Rh123 were analyzed by flow cytometer, the mRNA level of mdr1 was determined by RT-PCR and the protein levels of P-glycoprotein (P-gp) and mitogen-activated protein kinase were determined by Western blot.

KEY FINDINGS

Astragaloside II (0.08 mg/ml) showed strong potency to increase 5-fluorouracil cytotoxicity toward 5-fluorouracil-resistant human hepatic cancer cells Bel-7402/FU. The mechanism of Astragaloside II on P-gp-mediated MDR demonstrated that Astragaloside II significantly increased the intracellular accumulation of rhodamine 123 via inhibition of P-gp transport function. Based on the analysis of P-gp and mdr1 gene expression using Western blot and RT-PCR, the results revealed that Astragaloside II could downregulate the expression of the P-gp and mdr1 gene. In addition, Astragaloside II suppressed phosphorylation of extracellular signal regulated kinase 1/2, p38 and c-Jun N-terminal kinase.

CONCLUSIONS

The results suggested that Astragaloside II is a potent MDR reversal agent and may be a potential adjunctive agent for hepatic cancer chemotherapy.

Doxorubicin- and daunorubicin-induced regulation of Ca2+ and H+ fluxes through human bax inhibitor-1 reconstituted into membranes

Bax inhibitor-1 (BI-1) is an evolutionarily conserved cell death suppressor in both animals and plants. We examined the effect of doxorubicin (DXR) and daunorubicin (DNR), which are clinically important anthracycline compounds, on the functional regulation of BI-1 reconstituted into membranes. DXR and DNR inhibited the proton-induced efflux of encapsulated Ca(2+) from membranes in a drug concentration-dependent manner. Both compounds also reduced the H(+) influx activity of BI-1. The proteoliposomes containing BI-1 increased the quenching of DXR fluorescence by Cu(2+), and the fluorescence energy transfer between pyrene-labeled BI-1 and DXR was enhanced with increasing DXR concentrations. The dissociation constants and the number of binding sites for both drugs in BI-1 were determined to be in the range of 3.7-4.5 × 10(-6) m and approximately 4-5/BI-1 molecule, respectively, using a proteomicelle system. DXR also induced secondary structural changes in reconstituted BI-1 and abolished the ability of BI-1-overexpressing cells to protect against endoplasmic reticulum stress-induced cell death. However, when mitoxantrone was used instead of DNR and DXR as an anthracycline analog, no significant effects were observed. These results suggest that BI-1 can be considered to be a new cancer therapeutic target by anthracyclines because of its stimulatory effects in cancer/tumor progression.

Soluble Frizzled-7 receptor inhibits Wnt signaling and sensitizes hepatocellular carcinoma cells towards doxorubicin

BACKGROUND

There are limited therapeutic options for hepatocellular carcinoma (HCC), the most common liver malignancy worldwide. Recent studies have identified the Frizzled-7 receptor (FZD7), important for activation of Wnt-mediated signaling, as a potential therapeutic target for HCC and other cancers.

METHODS

We hypothesized that the extracellular domain of FZD7 (sFZD7) would be a clinically more relevant therapeutic modality than previously studied approaches to target FZD7. We expressed and purified sFZD7 from E. coli, and tested its functional activity to interact with Wnt3, its ability to inhibit Wnt3-mediated signaling, and its potential for combinatorial therapy in HCC.

RESULTS

sFZD7 pulled down Wnt3 from Huh7 cells, and decreased β-catenin/Tcf4 transcriptional activity in HCC cells. In vitro, sFZD7 dose-dependently decreased viability of three HCC cell lines (HepG2, Hep40, and Huh7, all with high FZD7 and Wnt3 mRNA), but had little effect on normal hepatocytes from three donors (all with low level FZD7 and Wnt3 mRNA). When combined with doxorubicin, sFZD7 enhanced the growth inhibitory effects of doxorubicin against HCC cells in vitro, and against Huh7 xenografts in vivo. Reduced expressions of c-Myc, cyclin D1, and survivin were observed in vitro and in vivo. Additionally, sFZD7 altered the levels of phosphorylated AKT and ERK1/2 induced by doxorubicin treatment in vitro, suggesting that several critical pathways are involved in the chemosensitizing effect of sFZD7.

CONCLUSIONS

We propose that sFZD7 is a feasible therapeutic agent with specific activity, which can potentially be combined with other chemotherapeutic agents for the improved management of HCC.

Using acetaminophen's toxicity mechanism to enhance cisplatin efficacy in hepatocarcinoma and hepatoblastoma cell lines

BACKGROUND/AIMS

Acetaminophen overdose causes hepatotoxicity mediated by toxic metabolites generated through the cytochrome P450 enzyme. The objective of this study was to investigate whether acetaminophen (AAP) can enhance cisplatin (CDDP) cytotoxicity against human hepatocarcinoma and hepatoblastoma cells in vitro and whether this effect can be prevented by N-acetylcysteine (NAC).

METHODS

In vitro studies (glutathione [GSH] level, cell viability, and immunoblot assays) were performed using human hepatocarcinoma and hepatoblastoma cells cultured in AAP, CDDP, and the combination of both with or without delayed NAC administration. The pharmacology and toxicology of high-dose AAP in rats were also examined.

RESULTS

Acetaminophen decreased GSH levels in liver cancer cells in a dose- and time-dependent manner. Acetaminophen combined with CDDP had enhanced cytotoxicity over CDDP alone. The cytotoxicity caused by AAP plus CDDP was decreased by NAC, with the effectiveness being time-dependent. The GSH level was lowered in the liver but not in the blood or the brain in rats treated with a high dose of AAP (1000 mg/kg). The expression of CYP2E1 protein, a key cytochrome P450 enzyme, varies among species but is not correlated to AAP sensitivity in liver cancer cells.

CONCLUSIONS

Our results suggest that a chemotherapeutic regimen containing both AAP and CDDP with delayed NAC rescue has the potential to enhance chemotherapeutic efficacy while decreasing adverse effects. This would be a promising approach particularly for hepatoblastomas regardless of cellular CYP2E1 protein level but could also be beneficial in other malignancies.

Antisense hypoxia-inducible factor 1alpha gene therapy enhances the therapeutic efficacy of doxorubicin to combat hepatocellular carcinoma

Hepatocellular carcinoma (HCC), one of the most common cancers worldwide, is resistant to anticancer drugs. Hypoxia is a major cause of tumor resistance to chemotherapy, and hypoxia-inducible factor (HIF)-1 is a key transcription factor in hypoxic responses. We have previously demonstrated that gene transfer of an antisense HIF-1alpha expression vector downregulates expression of HIF-1alpha and vascular endothelial growth factor (VEGF), and synergizes with immunotherapy to eradicate lymphomas. The aim of the present study was to determine whether gene transfer of antisense HIF-1alpha could enhance the therapeutic efficacy of doxorubicin to combat HCC. Both antisense HIF-1alpha therapy and doxorubicin suppressed the growth of subcutaneous human HepG2 tumors established in BALB/c nude mice, tumor angiogenesis, and cell proliferation, and induced tumor cell apoptosis. The combination therapy with antisense HIF-1alpha and doxorubicin was more effective in suppressing tumor growth, angiogenesis, and cell proliferation, and inducing cell apoptosis than the respective monotherapies. Gene transfer of antisense HIF-1alpha downregulated the expression of both HIF-1alpha and VEGF, whereas doxorubicin only downregulated VEGF expression. Antisense HIF-1alpha and doxorubicin synergized to downregulate VEGF expression. Both antisense HIF-1alpha and doxorubicin inhibited expression of proliferating cell nuclear antigen, and combined to exert even stronger inhibition of proliferating cell nuclear antigen expression. Antisense HIF-1alpha therapy warrants investigation as a therapeutic strategy to enhance the efficacy of doxorubicin for treating HCC.

The effect of doxorubicin on MEK-ERK signaling predicts its efficacy in HCC

BACKGROUND

Hepatocellular cancer (HCC) is a leading cause of cancer-related death worldwide. Historically, doxorubicin (DOX) has been widely used against unresectable HCC with variable response rates.

MATERIALS AND METHODS

We hypothesized that DOX combined with mitogen-activated protein kinase kinase-extracellular signal-regulated kinase (MEK-ERK) targeted therapy may provide enhanced anti-cancer effects. Human HCC cell lines (HepG2, Hep3B) were treated with DOX and MEK enzyme inhibitors, U0126 or PD184161, alone or in combination. Growth, apoptosis, and ERK expression/MEK activity were respectively determined by proliferation assay, DNA fragmentation enzyme-linked immunoassay or fluorochrome inhibitor of caspases, and Western blot.

RESULTS

DOX (0.01-1 microM) decreased cell proliferation in Hep3B cells (IC(50) approximately 0.12 microM) at 48 to 72 h; DOX was less effective in HepG2 cells (IC(50) approximately 0.25 microM). At early time points (30 min) after DOX treatment of Hep3B cells, MEK activity was unchanged at low doses and decreased at higher doses; after 24 h, phospho-ERK levels increased at higher doses. Contrarily, in HepG2 cells, DOX caused a sustained, dose-dependent increase in phospho-ERK levels at early and late time points. The MEK inhibitor U0126 decreased phospho-ERK in both HCC lines. In contrast to DOX, HepG2 cells were more sensitive than Hep3B cells to U0126. The combination of DOX with U0126 (or PD184161) resulted in greater inhibition of proliferation in HepG2 but not in Hep3B cells. This effect may be mediated in part by enhanced apoptosis.

CONCLUSIONS

The effect of DOX on early and late induction of MEK activity predicts its chemotherapeutic response in HCC. Furthermore, this effect may also determine the utility of MEK inhibitor combination treatment.