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.
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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; Marzec, Michal; Robertson, Erle S.; Slupianek, Artur; Wasik, Mariusz A.
I: Cancer Research, Bind 65, Nr. 17, 2005, s. 7800-7808.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
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.
N1 - M1 - Copyright (C) 2018 American Chemical Society (ACS). All Rights Reserved. CAPLUS AN 2005:972191(Journal)
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
VL - 65
SP - 7800
EP - 7808
JO - Cancer Research
JF - Cancer Research
SN - 0008-5472
IS - 17
ER -
ID: 202376216