Abstract
BackgroundFatty acid synthase (FASN) is highly expressed in various types of cancer and has an important role in carcinogenesis and metastasis. To clarify the mechanisms of FASN in liver cancer invasion and metastasis, the FASN protein interaction network in liver cancer was identified by targeted proteomic analysis.MethodsWound healing and Transwell assays was performed to observe the effect of FASN during migration and invasion in liver cancer. Isobaric tags for relative and absolute quantitation (iTRAQ)-based mass spectrometry were used to identify proteins interacting with FASN in HepG2 cells. Differential expressed proteins were validated by co-immunoprecipitation, western blot analyses and confocal microscopy. Western blot and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were performed to demonstrate the mechanism of FASN regulating metastasis.ResultsFASN knockdown inhibited migration and invasion of HepG2 and SMMC7721 cells. A total of, 79 proteins interacting with FASN were identified. Additionally, gene ontology term enrichment analysis indicated that the majority of biological regulation and cellular processes that the FASN-interacting proteins were associated with. Co-precipitation and co-localization of FASN with fascin actin-bundling protein 1 (FSCN1), signal-induced proliferation-associated 1 (SIPA1), spectrin β, non-erythrocytic 1 (SPTBN1) and CD59 were evaluated. Knockdown of FASN in liver cancer reduced the expression of FSCN1, SIPA1, SPTBN1 and CD59. Furthermore, inhibition of FASN, FSCN1 or SPTBN1 expression in liver cancer resulted in alterations of epithelial–mesenchymal transition (EMT)-associated markers E-cadherin, N-cadherin, vimentin and transcription factors, Snail and Twist, at the mRNA level, and changes in matrix metallopeptidase (MMP)-2 and MMP-9 protein expression.ConclusionThe results suggested that the FASN-interacting protein network produced by iTRAQ-based proteomic analyses may be involved in regulating invasion and metastasis in liver cancer by influencing EMT and the function of MMPs.
Highlights
Fatty acid synthase (FASN) is highly expressed in various types of cancer and has an important role in carcinogenesis and metastasis
Monoclonal or polyclonal antibodies against FASN, fascin actin-bundling protein 1 (FSCN1), signal-induced proliferation-associated 1 (SIPA1), spectrin β, nonerythrocytic 1 (SPTBN1), CD59, matrix metallopeptidase (MMP)-2 and MMP-9 were acquired from Abcam (Cambridge, MA, USA). β-actin was acquired from Santa Cruz Biotechnology, Inc. (Dallas, TX, USA)
Effect of FASN on cell migration and invasion in liver cancer To identify the effect of FASN during migration and invasion in liver cancer, a FASN-targeting siRNA was transfected into HepG2 and SMCC7721 cells
Summary
Fatty acid synthase (FASN) is highly expressed in various types of cancer and has an important role in carcinogenesis and metastasis. Cancer is a leading cause of mortality in economically developed countries and developing countries. Liver cancer remains the fifth most common malignant tumor in men and the seventh most common among women, worldwide, and is the third leading cause of cancer-associated mortality, exceeded only by stomach and lung cancer [2, 3]. Metastasis is considered a sign of deterioration and the major cause of morality for patients with liver cancer [6]. Effective treatment of metastatic liver cancer is limited, due to a lack of understanding of the mechanisms underlying the metastatic process [7, 8]. In order to develop effective therapeutic strategies, there is an urgent need to investigate the molecular basis of liver cancer metastasis
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