ABSTRACT
BACKGROUND: MUC5AC was recently identified to play important roles in the proliferation and metastasis of malignant mucinous lung tumor cells. Resveratrol (Res), a natural compound with anticancer effects in lung cancer cells, has been reported to inhibit mucin production in airway epithelial cells. This study aimed to investigate the inhibitory effect of Res on MUC5AC expression in lung mucinous adenocarcinoma cells and the potential mechanisms. METHODS: Mucus-producing A549 human lung carcinoma cells were used to test the effects of Res on SPDEF and MUC5AC expression. Gene and protein expression was assessed by real-time quantitative PCR (qPCR), immunofluorescence and western blotting assays. SPDEF lentivirus was used to upregulate SPDEF expression levels in mucus-producing A549 human lung carcinoma cells. Cell proliferation was assessed by Cell Counting Kit-8 (CCK-8) assay. RESULTS: Res decreased MUC5AC expression in an SPDEF-dependent manner in mucus-producing A549 human lung carcinoma cells, and this change was accompanied by decreased ERK expression and AKT pathway activation. Moreover, SPDEF was found to be overexpressed in lung adenocarcinoma (LUAD), especially in mucinous adenocarcinoma. In-vitro functional assays showed that overexpression of SPDEF reduced the chemosensitivity of A549 cells to cisplatin (DDP). In addition, Res treatment increased A549 cell chemosensitivity to DDP by inhibiting the SPDEF-MUC5AC axis. CONCLUSION: Our results indicate that the SPDEF-MUC5AC axis is associated with DDP sensitivity, and that Res decreases SPDEF and MUC5AC expression by inhibiting ERK and AKT signaling in A549 cells, which provides a potential pharmacotherapy for the prevention and therapeutic management of mucinous adenocarcinoma.
Subject(s)
Adenocarcinoma of Lung , Lung Neoplasms , Mucin 5AC/antagonists & inhibitors , Proto-Oncogene Proteins c-ets/metabolism , Resveratrol , A549 Cells , Adenocarcinoma of Lung/drug therapy , Adenocarcinoma of Lung/metabolism , Cisplatin/pharmacology , Drug Resistance, Neoplasm , Gene Expression Regulation, Neoplastic , Humans , Lung Neoplasms/drug therapy , Lung Neoplasms/metabolism , Mucin 5AC/genetics , Resveratrol/pharmacologyABSTRACT
Erythropoiesis is a complex multistage process that involves differentiation of early erythroid progenitors to enucleated mature red blood cells, in which lineage-specific transcription factors play essential roles. Erythroid Krüppel-like factor (EKLF/KLF1) is a pleiotropic erythroid transcription factor that is required for the proper maturation of the erythroid cells, whose expression and activation are tightly controlled in a temporal and differentiation stage-specific manner. Here, we uncover a novel role of G-protein pathway suppressor 2 (GPS2), a subunit of the nuclear receptor corepressor/silencing mediator of retinoic acid and thyroid hormone receptor corepressor complex, in erythrocyte differentiation. Our study demonstrates that knockdown of GPS2 significantly suppresses erythroid differentiation of human CD34+ cells cultured in vitro and xenotransplanted in nonobese diabetic/severe combined immunodeficiency/interleukin-2 receptor γ-chain null mice. Moreover, global deletion of GPS2 in mice causes impaired erythropoiesis in the fetal liver and leads to severe anemia. Flow cytometric analysis and Wright-Giemsa staining show a defective differentiation at late stages of erythropoiesis in Gps2-/- embryos. Mechanistically, GPS2 interacts with EKLF and prevents proteasome-mediated degradation of EKLF, thereby increasing EKLF stability and transcriptional activity. Moreover, we identify the amino acids 191-230 region in EKLF protein, responsible for GPS2 binding, that is highly conserved in mammals and essential for EKLF protein stability. Collectively, our study uncovers a previously unknown role of GPS2 as a posttranslational regulator that enhances the stability of EKLF protein and thereby promotes erythroid differentiation.
Subject(s)
Erythropoiesis/physiology , Intracellular Signaling Peptides and Proteins/physiology , Kruppel-Like Transcription Factors/physiology , Amino Acid Sequence , Animals , Cells, Cultured , Conserved Sequence , Erythroid Precursor Cells/cytology , Gene Knockdown Techniques , Hematopoietic Stem Cell Transplantation , Humans , Interleukin Receptor Common gamma Subunit/deficiency , Intracellular Signaling Peptides and Proteins/biosynthesis , Intracellular Signaling Peptides and Proteins/deficiency , Intracellular Signaling Peptides and Proteins/genetics , Kruppel-Like Transcription Factors/antagonists & inhibitors , Kruppel-Like Transcription Factors/chemistry , Liver/embryology , Mice , Mice, Inbred C57BL , Mice, Inbred NOD , Mice, SCID , Protein Interaction Mapping , Protein Processing, Post-Translational , Protein Stability , Proteolysis , RNA Interference , RNA, Small Interfering/genetics , Sequence Alignment , Sequence Homology, Amino Acid , Transcription, Genetic , Transplantation, Heterologous , Ubiquitination , Up-RegulationABSTRACT
Large negative differential conductance (NDC) at lower bias regime is a very desirable functional property for single molecular device. Due to the non-conjugated segment separating two conjugated branches, the single thiolated arylethynylene molecule with 9,10-dihydroanthracene core (denoted as TADHA) presents excellent NDC behavior in lower bias regime. Based on the ab initio calculation and non-equilibrium Green's function formalism, the NDC behavior of TADHA molecular device and the H2O-molecule-adsorption effects are studied systematically. The numerical results show that the NDC behavior of TADHA molecular junction originates from the Stark effect of the applied bias which splits the degeneration of the highest occupied molecular orbital (HOMO) and HOMO-1. The H2O molecule adsorbed on the terminal sulphur atom strongly suppresses the conductance of TADHA molecular device and destroys the NDC behavior in the lower bias regime. Single or separated H2O molecules adsorbed on the backbone of TADHA molecule can depress the energy levels of molecular orbitals, but have little effects on the NDC behavior of the TADHA molecular junction. Aggregate of several H2O molecules adsorbed on one branch of TADHA molecule can dramatically enhance the conductance and NDC behavior of the molecular junction, and result in rectifier behavior.
