Project description:The main adverse effect of tyrosine kinase inhibitors, such as sunitinib, is cardiac contractile dysfunction; however, the molecular mechanisms of this effect remain largely obscure. MicroRNAs (miRNAs) are key regulatory factors in both cardiovascular diseases and the tyrosine kinase pathway. Therefore, we analyzed the differential expression of miRNAs in the myocardium in mice after exposure to sunitinib using miRNA microarray. A significant downregulation of miR-146a was observed in the myocardium of sunitinib-treated mice, along with a 20% decrease in left ventricle ejection fraction (LVEF). The downregulation of miR-146a was further validated by RT-qPCR. Among the potential targets of miR-146a, we focused on Pln and Ank2, which are closely related to cardiac contractile dysfunction. Results of luciferase reporter assay confirmed that miR-146a directly targeted the 3' untranslated region of Pln and Ank2. Significant upregulation of PLN and ANK2 at the mRNA and protein levels was observed in the myocardium of sunitinib-treated mice. Cardiac-specific overexpression of miR-146a prevented the deteriorate effect of SNT on calcium transients, thereby alleviating the decreased contractility of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). SiRNA knockdown of PLN or ANK2 prevented sunitinib-induced suppression of contractility in hiPSC-CMs. Therefore, our in vivo and in vitro results showed that sunitinib downregulated miR-146a, which contributes to cardiac contractile dysfunction by regulating the downstream targets PLN and ANK2, and that upregulation of miR-146a alleviated the inhibitory effect of SNT on cardiac contractility. Thus, miR-146a could be a useful protective agent against sunitinib-induced cardiac dysfunction.
Project description:MicroRNAs (miRNAs) are small non-coding RNAs that function as modulators of gene expression. We previously showed that miR-146a-5p is upregulated in pancreatic islets treated with pro-inflammatory cytokines and in pancreatic sections from organ donors with type 1 diabetes (T1D). Other studies have associated overexpression of miR-146a-5p with β cell apoptosis and impaired insulin secretion; however, the molecular mechanisms mediating these effects remain elusive. To investigate the role of miR-146a-5p in β cell function, we developed stable MIN6 cell lines transduced with lentiviral vectors to either overexpress or inhibit the expression of miR-146a-5p. Monoclonal cell populations were treated with pro-inflammatory cytokines (IL1β, IFNg, and TNFα) to model T1D in vitro. We found that overexpression of miR-146a-5p increased the cell death of MIN6 cells under inflammatory stress, whereas inhibition of miR-146a-5p reversed these effects. Additionally, inhibition of miR-146a-5p increased mitochondrial DNA copy number, respiration rate, and ATP production, suggesting that miR-146a-5p inhibition improves mitochondrial function. In support of this finding, we also observed that miR-146a-5p is enriched in the mitochondria of MIN6 cells treated with cytokines. Consistently, bioinformatic analysis of RNA sequencing data using MIN6 stable cells showed enrichment of pathways related to insulin secretion, apoptosis, and mitochondrial function when the expression levels of miR-146a-5p were altered. Overall, the findings from our study show for the first time that miR-146a-5p upregulation during inflammatory stress may promote β cell dysfunction and death by suppressing mitochondrial function.
Project description:miR-146a is a NF-κB induced microRNA that serves as a feedback regulator of this critical pathway. In mice, deficiency of miR-146a results in hematolymphoid cancer at advanced ages as a consequence of constitutive NF-κB activity. In this study, we queried whether the deficiency of miR-146a contributes to B-cell oncogenesis. Combining miR-146a deficiency with transgenic expression of c-Myc led to the development of highly aggressive B-cell malignancies. Mice transgenic for c-Myc and deficient for miR-146a were characterized by significantly shortened survival, increased lymph node involvement, differential involvement of the spleen and a mature B-cell phenotype. High-throughput sequencing of the tumors revealed significant dysregulation of approximately 250 genes. Amongst these, the transcription factor Egr1 was consistently upregulated in mice deficient for miR-146a. Interestingly, transcriptional targets of Egr1 were enriched in both the high-throughput dataset and in a larger set of miR-146a-deficient tumors. miR-146a overexpression led to downregulation of Egr1 and downstream targets with concomitant decrease in cell growth. Direct targeting of the human EGR1 by miR-146a was seen by luciferase assay. Together our findings illuminate a bona fide role for miR-146a in the modulation of B-cell oncogenesis and reveal the importance of understanding microRNA function in a cell- and disease-specific context.
Project description:To gain insights into the mechanisms of dihydroberberine, sunitinib and dihydroberberine plus sunitinib on inhibition to A549 cells, we have employed whole genome microarray expression profiling as a discovery platform to identify different genes between dihydroberberine, sunitinib and dihydroberberine plus sunitinib-treated sample and control.
Project description:Renal cell carcinoma (RCC) represents about 2-3% of all cancers with over 400,000 new cases per year. Sunitinib, a vascular endothelial growth factor tyrosine kinase receptor inhibitor, has been used mainly for first-line treatment of metastatic clear-cell RCC with good or intermediate prognosis. However, about one third of metastatic RCC patients do not respond to sunitinib, leading to disease progression. Here we aim to find and characterize proteins associated with poor sunitinib response in a pilot proteomics study. 16 RCC tumors from patients responding (8) vs. non-responding (8) to sunitinib in 3 months after treatment initiation, together with their adjacent non-cancerous tissues, were analyzed using data independent acquisition mass spectrometry. Proteomics analysis quantified 1996 protein groups (q<0.01) and revealed 27 proteins deregulated between tumors non-responding vs. responding to sunitinib, representing a pattern of deregulated proteins potentially contributing to sunitinib resistance. Gene set enrichment analysis showed up-regulation of epithelial-to-mesenchymal transition with transgelin as one of the most significantly abundant protein. Transgelin expression was silenced by CRISPR/Cas9 and RNA interference, and the cells with reduced transgelin level exhibited significantly slower proliferation. Our data indicate that transgelin is an essential protein supporting RCC cell proliferation which could contribute to intrinsic sunitinib resistance.
Project description:To gain insights into the mechanisms of dihydroberberine, sunitinib and dihydroberberine plus sunitinib on inhibition to A549 cells, we have employed whole genome microarray expression profiling as a discovery platform to identify different genes between dihydroberberine, sunitinib and dihydroberberine plus sunitinib-treated sample and control. A549 cells were cultivated in the absence or presence of 25?mol/L dihydroberberine, 2?mol/L sunitinib, 25?mol/L dihydroberberine plus 2?mol/L sunitinib for 48 h, followed by the Agilent Whole Human Genome Oligo Microarray
Project description:Cystathionine γ-lyase downregulation contributes to hepatocyte injury and dysfunction via multiple signaling pathways by regulation of histone lysine methylation
Project description:Dysfunction of pancreatic alpha cells contributes to the pathophysiology of diabetes. Features of diabetic alpha cell dysfunction include glucagon hypersecretion, defects in proglucagon processing, and altered transcriptomic profile. The lack of an in vitro human alpha cell model has prevented the investigation, and potential correction, of these dysfunctional phenotypes. Here, we show that induction of endoplasmic reticulum stress in stem cell-derived alpha (SC-α) cells induces hypersecretion of glucagon. ER stress also increases the secretion of glicentin and expression of GLP-1, peptides produced by alternate cleavage of proglucagon by the prohormone convertase 1 (PC1/3) enzyme. Additionally, ER stress establishes a diabetic transcriptional state in SC-α cells characterized by downregulation of MAFB, as well as glycolysis and oxidative phosphorylation pathways. We show that sunitinib, a tyrosine kinase inhibitor, protects SC-α cells against the ER stress-induced glucagon hypersecretion phenotype. Thus, SC-α cell model can advance our knowledge of islets in health and diabetes.