Activation of Mammalian Target of Rapamycin in Transformed B Lymphocytes Is Nutrient Dependent but Independent of Akt, Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Kinase, Insulin Growth Factor-I, and Serum.

Pawel Wlodarski; Monika Kasprzycka; Xiaobin Liu; Michal Marzec; Erle S. Robertson; Artur Slupianek; Mariusz A. Wasik

doi:10.1158/0008-5472.CAN-04-4180

Activation of Mammalian Target of Rapamycin in Transformed B Lymphocytes Is Nutrient Dependent but Independent of Akt, Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Kinase, Insulin Growth Factor-I, and Serum.

Pawel Wlodarski, Monika Kasprzycka, Xiaobin Liu, Michal Marzec, Erle S. Robertson, Artur Slupianek, Mariusz A. Wasik

72 Citations (Scopus)

Abstract

The study examines the preponderance and mechanism of mammalian target of rapamycin (mTOR) activation in three distinct types of transformed B lymphocytes that differ in expression of the EBV genome. All three types [EBV-immortalized cells that express a broad spectrum of the virus-encoded genes (type III latency; EBV+/III), EBV-pos. cells that express only a subset of the EBV-encoded genes (EBV+/I), and EBV-neg., germinal center-derived cells (EBV-)] universally displayed activation of the mTOR signaling pathway. However, only the EBV+/III transformed B cells displayed also activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway that is considered to be the key activator of mTOR and of the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK pathway that coactivates one of the immediate targets of mTOR, p70 S6K1. Activation of the PI3K/Akt and MEK/ERK, but not of the mTOR pathway, was inhibited by serum withdrawal and restored by insulin growth factor-I. In contrast, activation of mTOR, but not PI3K/Akt and MEK/ERK, was sensitive to nutrient depletion. Both direct Akt (Akt inhibitors I-III) and a PI3K inhibitor (wortmannin at 1 nmol/L) suppressed Akt phosphorylation without significantly affecting mTOR activation. Furthermore, rapamycin, a potent and specific mTOR inhibitor, suppressed profoundly proliferation of cells from all three types of transformed B cells. U0126, a MEK inhibitor, had a moderate antiproliferative effect only on the EBV+/III cells. These results indicate that mTOR kinase activation is mediated in the transformed B cells by the mechanism(s) independent of the PI3K/Akt signaling pathway. They also suggest that inhibition of mTOR signaling might be effective in therapy of the large spectrum of B-cell lymphomas. [on SciFinder(R)]

Original language	English
Journal	Cancer Research
Volume	65
Issue number	17
Pages (from-to)	7800-7808
Number of pages	9
ISSN	0008-5472
DOIs	https://doi.org/10.1158/0008-5472.CAN-04-4180
Publication status	Published - 2005
Externally published	Yes

Keywords

B lymphocyte nutrient signaling transformation IGF lymphoma

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Wlodarski, P., Kasprzycka, M., Liu, X., Marzec, M., Robertson, E. S., Slupianek, A., & Wasik, M. A. (2005). Activation of Mammalian Target of Rapamycin in Transformed B Lymphocytes Is Nutrient Dependent but Independent of Akt, Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Kinase, Insulin Growth Factor-I, and Serum. Cancer Research, 65(17), 7800-7808. https://doi.org/10.1158/0008-5472.CAN-04-4180

Activation of Mammalian Target of Rapamycin in Transformed B Lymphocytes Is Nutrient Dependent but Independent of Akt, Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Kinase, Insulin Growth Factor-I, and Serum. / Wlodarski, Pawel; Kasprzycka, Monika; Liu, Xiaobin et al.
In: Cancer Research, Vol. 65, No. 17, 2005, p. 7800-7808.

Research output: Contribution to journal › Journal article › Research › peer-review

Wlodarski, P, Kasprzycka, M, Liu, X, Marzec, M, Robertson, ES, Slupianek, A & Wasik, MA 2005, 'Activation of Mammalian Target of Rapamycin in Transformed B Lymphocytes Is Nutrient Dependent but Independent of Akt, Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Kinase, Insulin Growth Factor-I, and Serum.', Cancer Research, vol. 65, no. 17, pp. 7800-7808. https://doi.org/10.1158/0008-5472.CAN-04-4180

Wlodarski P, Kasprzycka M, Liu X, Marzec M, Robertson ES, Slupianek A et al. Activation of Mammalian Target of Rapamycin in Transformed B Lymphocytes Is Nutrient Dependent but Independent of Akt, Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Kinase, Insulin Growth Factor-I, and Serum. Cancer Research. 2005;65(17):7800-7808. doi: 10.1158/0008-5472.CAN-04-4180

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title = "Activation of Mammalian Target of Rapamycin in Transformed B Lymphocytes Is Nutrient Dependent but Independent of Akt, Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Kinase, Insulin Growth Factor-I, and Serum.",

abstract = "The study examines the preponderance and mechanism of mammalian target of rapamycin (mTOR) activation in three distinct types of transformed B lymphocytes that differ in expression of the EBV genome. All three types [EBV-immortalized cells that express a broad spectrum of the virus-encoded genes (type III latency; EBV+/III), EBV-pos. cells that express only a subset of the EBV-encoded genes (EBV+/I), and EBV-neg., germinal center-derived cells (EBV-)] universally displayed activation of the mTOR signaling pathway. However, only the EBV+/III transformed B cells displayed also activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway that is considered to be the key activator of mTOR and of the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK pathway that coactivates one of the immediate targets of mTOR, p70 S6K1. Activation of the PI3K/Akt and MEK/ERK, but not of the mTOR pathway, was inhibited by serum withdrawal and restored by insulin growth factor-I. In contrast, activation of mTOR, but not PI3K/Akt and MEK/ERK, was sensitive to nutrient depletion. Both direct Akt (Akt inhibitors I-III) and a PI3K inhibitor (wortmannin at 1 nmol/L) suppressed Akt phosphorylation without significantly affecting mTOR activation. Furthermore, rapamycin, a potent and specific mTOR inhibitor, suppressed profoundly proliferation of cells from all three types of transformed B cells. U0126, a MEK inhibitor, had a moderate antiproliferative effect only on the EBV+/III cells. These results indicate that mTOR kinase activation is mediated in the transformed B cells by the mechanism(s) independent of the PI3K/Akt signaling pathway. They also suggest that inhibition of mTOR signaling might be effective in therapy of the large spectrum of B-cell lymphomas. [on SciFinder(R)]",

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T1 - Activation of Mammalian Target of Rapamycin in Transformed B Lymphocytes Is Nutrient Dependent but Independent of Akt, Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Kinase, Insulin Growth Factor-I, and Serum.

AU - Wlodarski, Pawel

AU - Kasprzycka, Monika

AU - Liu, Xiaobin

AU - Marzec, Michal

AU - Robertson, Erle S.

AU - Slupianek, Artur

AU - Wasik, Mariusz A.

PY - 2005

Y1 - 2005

N2 - The study examines the preponderance and mechanism of mammalian target of rapamycin (mTOR) activation in three distinct types of transformed B lymphocytes that differ in expression of the EBV genome. All three types [EBV-immortalized cells that express a broad spectrum of the virus-encoded genes (type III latency; EBV+/III), EBV-pos. cells that express only a subset of the EBV-encoded genes (EBV+/I), and EBV-neg., germinal center-derived cells (EBV-)] universally displayed activation of the mTOR signaling pathway. However, only the EBV+/III transformed B cells displayed also activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway that is considered to be the key activator of mTOR and of the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK pathway that coactivates one of the immediate targets of mTOR, p70 S6K1. Activation of the PI3K/Akt and MEK/ERK, but not of the mTOR pathway, was inhibited by serum withdrawal and restored by insulin growth factor-I. In contrast, activation of mTOR, but not PI3K/Akt and MEK/ERK, was sensitive to nutrient depletion. Both direct Akt (Akt inhibitors I-III) and a PI3K inhibitor (wortmannin at 1 nmol/L) suppressed Akt phosphorylation without significantly affecting mTOR activation. Furthermore, rapamycin, a potent and specific mTOR inhibitor, suppressed profoundly proliferation of cells from all three types of transformed B cells. U0126, a MEK inhibitor, had a moderate antiproliferative effect only on the EBV+/III cells. These results indicate that mTOR kinase activation is mediated in the transformed B cells by the mechanism(s) independent of the PI3K/Akt signaling pathway. They also suggest that inhibition of mTOR signaling might be effective in therapy of the large spectrum of B-cell lymphomas. [on SciFinder(R)]

AB - The study examines the preponderance and mechanism of mammalian target of rapamycin (mTOR) activation in three distinct types of transformed B lymphocytes that differ in expression of the EBV genome. All three types [EBV-immortalized cells that express a broad spectrum of the virus-encoded genes (type III latency; EBV+/III), EBV-pos. cells that express only a subset of the EBV-encoded genes (EBV+/I), and EBV-neg., germinal center-derived cells (EBV-)] universally displayed activation of the mTOR signaling pathway. However, only the EBV+/III transformed B cells displayed also activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway that is considered to be the key activator of mTOR and of the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK pathway that coactivates one of the immediate targets of mTOR, p70 S6K1. Activation of the PI3K/Akt and MEK/ERK, but not of the mTOR pathway, was inhibited by serum withdrawal and restored by insulin growth factor-I. In contrast, activation of mTOR, but not PI3K/Akt and MEK/ERK, was sensitive to nutrient depletion. Both direct Akt (Akt inhibitors I-III) and a PI3K inhibitor (wortmannin at 1 nmol/L) suppressed Akt phosphorylation without significantly affecting mTOR activation. Furthermore, rapamycin, a potent and specific mTOR inhibitor, suppressed profoundly proliferation of cells from all three types of transformed B cells. U0126, a MEK inhibitor, had a moderate antiproliferative effect only on the EBV+/III cells. These results indicate that mTOR kinase activation is mediated in the transformed B cells by the mechanism(s) independent of the PI3K/Akt signaling pathway. They also suggest that inhibition of mTOR signaling might be effective in therapy of the large spectrum of B-cell lymphomas. [on SciFinder(R)]

KW - B lymphocyte nutrient signaling transformation IGF lymphoma

U2 - 10.1158/0008-5472.CAN-04-4180

DO - 10.1158/0008-5472.CAN-04-4180

M3 - Journal article

SN - 0008-5472

VL - 65

SP - 7800

EP - 7808

JO - Cancer Research

JF - Cancer Research

IS - 17

ER -