7-Ketocholesterol induces P-glycoprotein through PI3K/mTOR signaling in hepatoma cells

Sheng Fan Wang, Yueh Ching Chou, Nirmal Mazumder, Fu Jen Kao, Eslie D. Nagy, Peter Guengerich, Cheng Huang, Hsin Chen Lee, Ping Shan Lai, Yune Fang Ueng

Research output: Contribution to journalArticle

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Abstract

7-Ketocholesterol (7-KC) is found at an elevated level in patients with cancer and chronic liver disease. The up-regulation of an efflux pump, P-glycoprotein (P-gp) leads to drug resistance. To elucidate the effect of 7-KC on P-gp, P-gp function and expression were investigated in hepatoma cell lines Huh-7 and HepG2 and in primary hepatocyte-derived HuS-E/2 cells. At a subtoxic concentration, 48-h exposure to 7-KC reduced the intracellular accumulation and cytotoxicity of P-gp substrate doxorubicin in hepatoma cells, but not in HuS-E/2 cells. In Huh-7 cells, 7-KC elevated efflux function through the activation of phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway. 7-KC activated the downstream protein synthesis initiation factor 4E-BP1 and induced P-gp expression posttranscriptionally. The stimulation of efflux was reversible and could not be prevented by N-acetyl cysteine. Total cellular ATP content remained the same, whereas the lactate production was increased and fluorescence lifetime of protein-bound NADH was shortened. These changes suggested a metabolic shift to glycolysis, but glycolytic inhibitors did not eliminate 7-KC-mediated P-gp induction. These results demonstrate that 7-KC induces P-gp through PI3K/mTOR signaling and decreased the cell-killing efficacy of doxorubicin in hepatoma cells.

Original languageEnglish
Pages (from-to)548-560
Number of pages13
JournalBiochemical Pharmacology
Volume86
Issue number4
DOIs
Publication statusPublished - 2013

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Phosphatidylinositol 3-Kinase
P-Glycoprotein
Sirolimus
Hepatocellular Carcinoma
Doxorubicin
Acetylcysteine
Peptide Initiation Factors
Glycolysis
Liver Neoplasms
Cytotoxicity
7-ketocholesterol
Drug Resistance
Liver
NAD
Cysteine
Liver Diseases
Hepatocytes
Lactic Acid
Proteins
Chronic Disease

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Pharmacology

Cite this

Wang, S. F., Chou, Y. C., Mazumder, N., Kao, F. J., Nagy, E. D., Guengerich, P., ... Ueng, Y. F. (2013). 7-Ketocholesterol induces P-glycoprotein through PI3K/mTOR signaling in hepatoma cells. Biochemical Pharmacology, 86(4), 548-560. https://doi.org/10.1016/j.bcp.2013.06.006
Wang, Sheng Fan ; Chou, Yueh Ching ; Mazumder, Nirmal ; Kao, Fu Jen ; Nagy, Eslie D. ; Guengerich, Peter ; Huang, Cheng ; Lee, Hsin Chen ; Lai, Ping Shan ; Ueng, Yune Fang. / 7-Ketocholesterol induces P-glycoprotein through PI3K/mTOR signaling in hepatoma cells. In: Biochemical Pharmacology. 2013 ; Vol. 86, No. 4. pp. 548-560.
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abstract = "7-Ketocholesterol (7-KC) is found at an elevated level in patients with cancer and chronic liver disease. The up-regulation of an efflux pump, P-glycoprotein (P-gp) leads to drug resistance. To elucidate the effect of 7-KC on P-gp, P-gp function and expression were investigated in hepatoma cell lines Huh-7 and HepG2 and in primary hepatocyte-derived HuS-E/2 cells. At a subtoxic concentration, 48-h exposure to 7-KC reduced the intracellular accumulation and cytotoxicity of P-gp substrate doxorubicin in hepatoma cells, but not in HuS-E/2 cells. In Huh-7 cells, 7-KC elevated efflux function through the activation of phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway. 7-KC activated the downstream protein synthesis initiation factor 4E-BP1 and induced P-gp expression posttranscriptionally. The stimulation of efflux was reversible and could not be prevented by N-acetyl cysteine. Total cellular ATP content remained the same, whereas the lactate production was increased and fluorescence lifetime of protein-bound NADH was shortened. These changes suggested a metabolic shift to glycolysis, but glycolytic inhibitors did not eliminate 7-KC-mediated P-gp induction. These results demonstrate that 7-KC induces P-gp through PI3K/mTOR signaling and decreased the cell-killing efficacy of doxorubicin in hepatoma cells.",
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Wang, SF, Chou, YC, Mazumder, N, Kao, FJ, Nagy, ED, Guengerich, P, Huang, C, Lee, HC, Lai, PS & Ueng, YF 2013, '7-Ketocholesterol induces P-glycoprotein through PI3K/mTOR signaling in hepatoma cells', Biochemical Pharmacology, vol. 86, no. 4, pp. 548-560. https://doi.org/10.1016/j.bcp.2013.06.006

7-Ketocholesterol induces P-glycoprotein through PI3K/mTOR signaling in hepatoma cells. / Wang, Sheng Fan; Chou, Yueh Ching; Mazumder, Nirmal; Kao, Fu Jen; Nagy, Eslie D.; Guengerich, Peter; Huang, Cheng; Lee, Hsin Chen; Lai, Ping Shan; Ueng, Yune Fang.

In: Biochemical Pharmacology, Vol. 86, No. 4, 2013, p. 548-560.

Research output: Contribution to journalArticle

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T1 - 7-Ketocholesterol induces P-glycoprotein through PI3K/mTOR signaling in hepatoma cells

AU - Wang, Sheng Fan

AU - Chou, Yueh Ching

AU - Mazumder, Nirmal

AU - Kao, Fu Jen

AU - Nagy, Eslie D.

AU - Guengerich, Peter

AU - Huang, Cheng

AU - Lee, Hsin Chen

AU - Lai, Ping Shan

AU - Ueng, Yune Fang

PY - 2013

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AB - 7-Ketocholesterol (7-KC) is found at an elevated level in patients with cancer and chronic liver disease. The up-regulation of an efflux pump, P-glycoprotein (P-gp) leads to drug resistance. To elucidate the effect of 7-KC on P-gp, P-gp function and expression were investigated in hepatoma cell lines Huh-7 and HepG2 and in primary hepatocyte-derived HuS-E/2 cells. At a subtoxic concentration, 48-h exposure to 7-KC reduced the intracellular accumulation and cytotoxicity of P-gp substrate doxorubicin in hepatoma cells, but not in HuS-E/2 cells. In Huh-7 cells, 7-KC elevated efflux function through the activation of phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway. 7-KC activated the downstream protein synthesis initiation factor 4E-BP1 and induced P-gp expression posttranscriptionally. The stimulation of efflux was reversible and could not be prevented by N-acetyl cysteine. Total cellular ATP content remained the same, whereas the lactate production was increased and fluorescence lifetime of protein-bound NADH was shortened. These changes suggested a metabolic shift to glycolysis, but glycolytic inhibitors did not eliminate 7-KC-mediated P-gp induction. These results demonstrate that 7-KC induces P-gp through PI3K/mTOR signaling and decreased the cell-killing efficacy of doxorubicin in hepatoma cells.

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