Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Uncoupling effects of ERalfa on LKB1/AMPK interaction upon adiponectin exposure in breast cancer

ABSTRACT: Adipose tissue is a metabolic and endocrine organ that secretes numerous bioactive molecules called adipocytokines. Among these, adiponectin has been argued to have a crucial role in obesity-associated breast cancer. The key molecule of adiponectin signaling is AMP-activated protein kinase (AMPK), mainly activated by Liver Kinase B1 (LKB1). Here, we demonstrated how the ERalfa/LKB1 interaction may negatively interfere with the capability of LKB1 to phosphorylate AMPK and then inhibit its downstream signaling TSC2/mTOR/p70S6k. In MCF-7 cells upon adiponectin AMPK signaling was not working, keeping its downstream protein Acetyl-CoA Carboxylase (ACC) still active. In contrast, in MDA-MB-231 cells the phosphorylation of AMPK and ACC was enhanced with consequent inhibition of both lipogenesis and cell growth. Thus, upon adiponectin, ERalfa signaling switched the energy balance of breast cancer cells towards a lipogenic phenotype. In other words, adiponectin in all the concentrations tested played an inhibitory role on ERalpha-negative breast cancer cell growth and progression either in vitro or in vivo. In contrast, low adiponectin levels, similar to those circulating in obese patients, worked on ERalfa-positive cells as a growth factor, stimulating their growth and progression. The latter effect seems to be blunted in vivo only in the presence of high adiponectin concentration. Based on the present results, it can be concluded that if we prospectively address adiponectin as a pharmacological tool, a separate therapeutic treatment should be carefully assessed in ERalfa-positive and negative breast-cancer patients.

INSTRUMENT(S): Illumina HiSeq 2500

ORGANISM(S): Homo sapiens

SUBMITTER: Domenico Memoli

PROVIDER: E-MTAB-6120 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Notch signaling is frequently hyperactivated in breast cancer, but how the enhanced signaling contributes to the tumor process is less well understood. In this report, we identify the proinflammatory cytokine interleukin-6 (IL-6) as a novel Notch target in breast tumor cells. Enhanced Notch signaling upregulated IL-6 expression at the transcriptional level, leading to activation of autocrine and paracrine JAK/STAT signaling. IL-6 upregulation was mediated by non-canonical Notch signaling, as it could be effectuated by a cytoplasmically localized Notch intracellular domain and was independent on the DNA-binding protein CSL. Instead, Notch-mediated IL-6 upregulation was controlled by two other factors: IKKÎ², a protein in the NF-kB signaling cascade, and p53. Activation of IL-6 by Notch required IKKÎ² function, but interestingly, did not engage canonical NF-ÎºB signaling, in contrast to IL-6 activation by inflammatory agents such as tumor necrosis factor, which requires canonical NF-ÎºB signaling. With regard to p53 status, IL-6 expression was upregulated by Notch when p53 was mutated or lost, but restoring wildtype 53 into p53-mutated or -deficient cells abrogated the IL-6 upregulation. Furthermore, Notch-induced genome-wide transcriptomes from p53 wildtype and -mutated breast tumor cell lines differed extensively, and in a subset of genes upregulated by Notch in a p53-mutant cell line, upregulation was reduced by wildtype p53. In conclusion, we identify IL-6 as a novel non-canonical Notch target gene, and reveal roles for p53 and IKKÎ² in non-canonical Notch signaling in breast cancer and in the generation of cell context-dependent diversity in the Notch signaling output. 30 microarray samples consisting of MCF7 (ER+, wild-type p53, luminal type B breast cancer) and MDA-MB-231 (ER-, mutated p53, basal breast cancer) cells cultured on immobilized 1 Î¼g/ml JAGGED1-Fc or 1 Î¼g/ml DLL4-Fc or 1 Î¼g/ml Fc control with or without 5 Î¼M DAPT for 6 hours in 3 biological replicates.

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Uncoupling effects of ERalfa on LKB1/AMPK interaction upon adiponectin exposure in breast cancer

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