Dataset Information

IKK Promotes Cytokine-Induced and Cancer-Associated AMPK Activity and Attenuates Phenformin-Induced Cell Death in LKB1-Deficient Cells

ABSTRACT: The 5' AMP-activated protein kinase (AMPK) is a master energy sensing kinase that is regulated by phosphorylation of Thr172 in its activation loop. Three kinases can phosphorylate AMPK at Thr172: the tumor suppressor LKB1, CAMKK2 and TAK1. While LKB1- and CAMKK2-mediated AMPK Thr172 phosphorylation have been well-characterized, much less is known about TAK1-dependent AMPK phosphorylation. An important target of TAK1 is IκB kinase (IKK) which controls NF-B transcription factor activation. Here, we tested the hypothesis that IKK acted downstream of TAK1 to activate AMPK by phosphorylating Thr172. IKK was required for phosphorylation of Thr172 in AMPK in response to treatment with IL-1 or TNF- treatment or by TAK1 overexpression. Additionally, IKK regulated basal AMPK Thr172 phosphorylation in several cancer cell types independently of TAK1, indicating that other modes of IKK activation could lead to AMPK activation. We found that IKK directly phosphorylated AMPK at Thr172 independently of LKB1 or energy stress. This finding indicated that while LKB1 activates AMPK as a sensor of energetic stress, IKK activated AMPK in response to extracellular inflammatory signals and through distinct pathways downstream of IKK activation. Accordingly, in LKB1-deficient cells, IKK inhibition caused a reduction in AMPK Thr172 phosphorylation in response to the mitochondrial inhibitor phenformin. This response led to enhanced apoptosis and suggests that IKK inhibition in combination with phenformin could be used clinically to treat patients with LKB1-deficient cancers.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Ricardo Antonia

LAB HEAD: Albert Baldwin

PROVIDER: PXD009897 | Pride | 2018-07-16

REPOSITORIES: pride

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IKK promotes cytokine-induced and cancer-associated AMPK activity and attenuates phenformin-induced cell death in LKB1-deficient cells.

Antonia Ricardo J RJ Baldwin Albert S AS

Science signaling 20180710 538

The 5' AMP-activated protein kinase (AMPK) is an energy sensor that is activated upon phosphorylation of Thr<sup>172</sup> in its activation loop by the kinase LKB1, CAMKK2, or TAK1. TAK1-dependent AMPK phosphorylation of Thr<sup>172</sup> is less well characterized than phosphorylation of this site by LKB1 or CAMKK2. An important target of TAK1 is IκB kinase (IKK), which controls the activation of the transcription factor NF-κB. We tested the hypothesis that IKK acted downstream of TAK1 to acti ...[more]

PMID: 29991651

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Project description:Purpose: Mutations in STK11 (LKB1) occur in 17% of lung adenocarcinoma (LUAD) and drive a suppressive (cold) tumor immune microenvironment (TME) and resistance to immunotherapy. The mechanisms underpin the establishment and maintenance of a cold TME in LKB1 mutant LUAD remain poorly understood and the identification of downstream effectors is critical to inform therapeutic strategies to invigorate antitumor immunity. In this study, we investigated the association between inactivation of AMPK, one of the downstream substrates of LKB1, and immune evasion in human LUAD as well as the causal role of AMPK on TME in genetically engineered mouse model (GEMM) of LUAD. Experimental Design: We modeled AMPK inactivation in vivo using GEMM by deleting both AMPKα1 (Prkaa1) and AMPKα2 (Prkaa2) in KrasG12D-driven LUAD (KAA). Furthermore, we investigated the impact of AMPK inactivation on immune cell infiltration and global gene-expression programs of murine LUAD. Gene expression signature from AMPK-deficient murine LUAD was further compared to that of Lkb1 deficient murineLUAD as well as human LUAD with either LKB1 mutation or attenuated AMPK phosphorylation. Results: Inactivation of both AMPKα1 and AMPKα2 accelerates KrasG12D-driven LUAD. AMPK-deficient tumors are characterized with reduced infiltration of CD8+/CD4+ T cells and gene signatures associated with compromised immune microenvironment, which resembles LKB1-deficient murine and human LUAD (KL) as well as LKB1-wildtype LUAD with reduced AMPK phosphorylation. Attenuation of the MHC Class 1 component ß2 microglobulin (ß2M) was identified as a shared feature in KL and KAA murine LUAD as well as in human LUAD with either LKB1 mutations or reduced AMPK phosphorylation. Furthermore, reactivation of AMPK by expression of constitutive active form of AMPKα1 leads to restoration of ß2M level in LKB1 mutant LUAD cells. Conclusions: The results identify attenuation of the LKB1 substrate AMPK as an important mechanism for decreased MHC Class 1 expression and immune evasion in LKB1 mutant LUAD. Translational relevance: LKB1 loss-of-function mutations rank as the third most common genetic alterations found in lung adenocarcinoma and associated with immune evasion. In the current study, on the basis of GEMM of LUAD we established the causal relationship between inactivation of the LKB1 substrate AMPK and immune evasion. Furthermore we find that the status of AMPK phosphorylation is more sensitive than LKB1 mutation in predicting impaired tumor immune microenvironment and likely also for the resistance to immunotherapy. The results also suggest that restoration of AMPK activity could increase the number of patients benefiting from immunotherapy.

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	AMPK_IKK_Run1.raw	Raw
	AMPK_IKK_Run2.raw	Raw
	AMPK_Run1.raw	Raw
	AMPK_Run2.raw	Raw
	F023290.dat	Other