Abstract:
:The PI3K/AKT/mTOR pathway, which is aberrantly stimulated in many cancer cells, has emerged as a target for therapy. However, mTORC1/S6K also mediates negative feedback loops that attenuate upstream signaling. Suppression of these feedback loops opposes the growth-suppressive effects of mTOR inhibitors and leads to drug resistance. Here, we demonstrate that treatment of PANC-1 or MiaPaCa-2 pancreatic ductal adenocarcinoma (PDAC) cells with the dual PI3K/mTOR kinase inhibitor (PI3K/TOR-KI) BEZ235 blocked mTORC1/S6K activation (scored by S6 phosphorylation at Ser(240/244)), mTORC1/4E-BP1 (assayed by 4E-BP1 phosphorylation at Thr(37/46)), and mTORC2-mediated AKT phosphorylation at Ser(473), in a concentration-dependent manner. Strikingly, BEZ235 markedly enhanced the MEK/ERK pathway in a dose-dependent manner. Maximal ERK overactivation coincided with complete inhibition of phosphorylation of AKT and 4E-BP1. ERK overactivation was induced by other PI3K/TOR-KIs, including PKI-587 and GDC-0980. The MEK inhibitors U126 or PD0325901 prevented ERK overactivation induced by PI3K/TOR-KIs. The combination of BEZ235 and PD0325901 caused a more pronounced inhibition of cell growth than that produced by each inhibitor individually. Mechanistic studies assessing PI3K activity in single PDAC cells indicate that PI3K/TOR-KIs act through a PI3K-independent pathway. Doses of PI3K/TOR-KIs that enhanced MEK/ERK activation coincided with those that inhibited mTORC2-mediated AKT phosphorylation on Ser(473), suggesting a role of mTORC2. Knockdown of RICTOR via transfection of siRNA markedly attenuated the enhancing effect of BEZ235 on ERK phosphorylation. We propose that dual PI3K/mTOR inhibitors suppress a novel negative feedback loop mediated by mTORC2, thereby leading to enhanced MEK/ERK pathway activity in pancreatic cancer cells.
journal_name
Mol Cancer Therjournal_title
Molecular cancer therapeuticsauthors
Soares HP,Ming M,Mellon M,Young SH,Han L,Sinnet-Smith J,Rozengurt Edoi
10.1158/1535-7163.MCT-14-0669subject
Has Abstractpub_date
2015-04-01 00:00:00pages
1014-23issue
4eissn
1535-7163issn
1538-8514pii
1535-7163.MCT-14-0669journal_volume
14pub_type
杂志文章abstract::Bortezomib is highly effective in the treatment of multiple myeloma; however, emergent drug resistance is common. Consequently, we employed CRISPR targeting 19,052 human genes to identify unbiased targets that contribute to bortezomib resistance. Specifically, we engineered an RPMI8226 multiple myeloma cell line to ex...
journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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更新日期:2017-12-01 00:00:00
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-07-0575
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-10-0191
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pub_type: 杂志文章
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-17-0657
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pub_type: 杂志文章
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-05-0455
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pub_type: 杂志文章
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-12-0529
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-10-0581
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-14-0399
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-06-0305
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-12-1007
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-07-0117
更新日期:2007-11-01 00:00:00
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-09-0407
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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pub_type: 杂志文章
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更新日期:2019-06-01 00:00:00
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-14-0280
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pub_type: 杂志文章
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-13-0052
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-17-0288
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-05-0126
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-16-0580
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-05-0266
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pub_type: 杂志文章
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pub_type: 杂志文章
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更新日期:2021-01-01 00:00:00
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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