ABSTRACT
This corrects the article DOI: 10.1038/onc.2017.75.
ABSTRACT
Recent evidences suggest that stearoyl-CoA-desaturase 1 (SCD1), the enzyme involved in monounsaturated fatty acids synthesis, has a role in several cancers. We previously demonstrated that SCD1 is important in lung cancer stem cells survival and propagation. In this article, we first show, using primary cell cultures from human lung adenocarcinoma, that the effectors of the Hippo pathway, Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), are required for the generation of lung cancer three-dimensional cultures and that SCD1 knock down and pharmacological inhibition both decrease expression, nuclear localization and transcriptional activity of YAP and TAZ. Regulation of YAP/TAZ by SCD1 is at least in part dependent upon ß-catenin pathway activity, as YAP/TAZ downregulation induced by SCD1 blockade can be rescued by the addition of exogenous wnt3a ligand. In addition, SCD1 activation of nuclear YAP/TAZ requires inactivation of the ß-catenin destruction complex. In line with the in vitro findings, immunohistochemistry analysis of lung adenocarcinoma samples showed that expression levels of SCD1 co-vary with those of ß-catenin and YAP/TAZ. Mining available gene expression data sets allowed to observe that high co-expression levels of SCD1, ß-catenin, YAP/TAZ and downstream targets have a strong negative prognostic value in lung adenocarcinoma. Finally, bioinformatics analyses directed to identify which gene combinations had synergistic effects on clinical outcome in lung cancer showed that poor survival is associated with high co-expression of SCD1, ß-catenin and the YAP/TAZ downstream target birc5. In summary, our data demonstrate for the first time the involvement of SCD1 in the regulation of the Hippo pathway in lung cancer, and point to fatty acids metabolism as a key regulator of lung cancer stem cells.
Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Adenocarcinoma/metabolism , Cell Nucleus/metabolism , Intracellular Signaling Peptides and Proteins/metabolism , Lung Neoplasms/metabolism , Neoplastic Stem Cells/metabolism , Phosphoproteins/metabolism , Stearoyl-CoA Desaturase/metabolism , Adenocarcinoma/mortality , Adenocarcinoma/pathology , Adenocarcinoma of Lung , Axin Signaling Complex/metabolism , Down-Regulation , Fatty Acids/metabolism , Female , HEK293 Cells , Hippo Signaling Pathway , Humans , Immunohistochemistry , Inhibitor of Apoptosis Proteins/metabolism , Lung Neoplasms/mortality , Lung Neoplasms/pathology , Male , Neoplasm Proteins/metabolism , Primary Cell Culture , Prognosis , Protein Serine-Threonine Kinases/metabolism , Protein Stability , RNA, Messenger/metabolism , Stearoyl-CoA Desaturase/antagonists & inhibitors , Stearoyl-CoA Desaturase/genetics , Survivin , Trans-Activators , Transcription Factors , Transcriptional Coactivator with PDZ-Binding Motif Proteins , Wnt3A Protein/metabolism , YAP-Signaling ProteinsABSTRACT
BACKGROUND: Aberrant choline metabolism has been proposed as a novel cancer hallmark. We recently showed that epithelial ovarian cancer (EOC) possesses an altered MRS-choline profile, characterised by increased phosphocholine (PCho) content to which mainly contribute over-expression and activation of choline kinase-alpha (ChoK-alpha). METHODS: To assess its biological relevance, ChoK-alpha expression was downmodulated by transient RNA interference in EOC in vitro models. Gene expression profiling by microarray analysis and functional analysis was performed to identify the pathway/functions perturbed in ChoK-alpha-silenced cells, then validated by in vitro experiments. RESULTS: In silenced cells, compared with control, we observed: (I) a significant reduction of both CHKA transcript and ChoK-alpha protein expression; (II) a dramatic, proportional drop in PCho content ranging from 60 to 71%, as revealed by (1)H-magnetic spectroscopy analysis; (III) a 35-36% of cell growth inhibition, with no evidences of apoptosis or modification of the main cellular survival signalling pathways; (IV) 476 differentially expressed genes, including genes related to lipid metabolism. Ingenuity pathway analysis identified cellular functions related to cell death and cellular proliferation and movement as the most perturbed. Accordingly, CHKA-silenced cells displayed a significant delay in wound repair, a reduced migration and invasion capability were also observed. Furthermore, although CHKA silencing did not directly induce cell death, a significant increase of sensitivity to platinum, paclitaxel and doxorubicin was observed even in a drug-resistant context. CONCLUSION: We showed for the first time in EOC that CHKA downregulation significantly decreased the aggressive EOC cell behaviour also affecting cells' sensitivity to drug treatment. These observations open the way to further analysis for ChoK-alpha validation as a new EOC therapeutic target to be used alone or in combination with conventional drugs.
Subject(s)
Choline Kinase/genetics , Neoplasms, Glandular and Epithelial/drug therapy , Neoplasms, Glandular and Epithelial/enzymology , Ovarian Neoplasms/drug therapy , Ovarian Neoplasms/enzymology , Carcinoma, Ovarian Epithelial , Cell Death/drug effects , Cell Death/genetics , Cell Line, Tumor , Cell Movement/drug effects , Cell Movement/genetics , Cell Proliferation/drug effects , Choline/genetics , Choline/metabolism , Choline Kinase/metabolism , Down-Regulation/drug effects , Doxorubicin/pharmacology , Female , Humans , Lipid Metabolism/drug effects , Lipid Metabolism/genetics , Molecular Targeted Therapy , Neoplasms, Glandular and Epithelial/genetics , Neoplasms, Glandular and Epithelial/metabolism , Ovarian Neoplasms/genetics , Ovarian Neoplasms/metabolism , Paclitaxel/pharmacology , Phosphorylcholine/metabolism , Platinum/pharmacology , RNA Interference/drug effects , Signal Transduction/drug effects , TranscriptomeABSTRACT
BACKGROUND: Limited knowledge is available on alterations induced by cytostatic drugs on magnetic resonance spectroscopy (MRS) and imaging (MRI) parameters of human cancers, in absence of apoptosis or cytotoxicity. We here investigated the effects of a cytostatic cisplatin (CDDP) treatment on (1)H MRS and MRI of HER2-overexpressing epithelial ovarian cancer (EOC) cells and in vivo xenografts. METHODS: High-resolution MRS analyses were performed on in vivo passaged SKOV3.ip cells and cell/tissue extracts (16.4 or 9.4 T). In vivo MRI/MRS quantitative analyses (4.7 T) were conducted on xenografts obtained by subcutaneous implantation of SKOV3.ip cells in SCID mice. The apparent diffusion coefficient (ADC) and metabolite levels were measured. RESULTS: CDDP-induced cytostatic effects were associated with a metabolic shift of cancer cells towards accumulation of MRS-detected neutral lipids, whereas the total choline profile failed to be perturbed in both cultured cells and xenografts. In vivo MRI examinations showed delayed tumour growth in the CDDP-treated group, associated with early reduction of the ADC mean value. CONCLUSION: This study provides an integrated set of information on cancer metabolism and physiology for monitoring the response of an EOC model to a cytostatic chemotherapy, as a basis for improving the interpretation of non-invasive MR examinations of EOC patients.