Project description:To assess the effects of small molecules SP100030 and Selinexor on Jurkat T cells activated by PMA/Ionomycin after 6 hours of activation and treatment
Project description:NPM1-mutated acute myeloid leukemia (AML) accounts for one third of AML in adults. NPM1-mutated AML maintenance depends on the interaction between mutated NPM1 (NPM1c) and the nuclear exporter Exportin 1 (XPO1). In this work, we show that continous XPO1 inhibition is necessary to achieve stable disruption of the NPM1c-XPO1 interaction and to induce HOX downregulation and differentiation of AML cells with mutated NPM1. In contrast, intermittent XPO1 inhibition only results in minimal transcriptional perturbation and limited antileukemic activity.
Project description:Mislocalization of oncogenes and tumor suppressors resulting from aberrant nuclear export promotes uncontrolled cell proliferation and growth transformation of cancer cells. We performed a genome-wide CRISPR-Cas9 screening in matched primary and KSHV-transformed cells, and identified genes that were pro-growth and growth-suppressive of both types of cells, of which exportin XPO1 was a critical factor for the survival of transformed cells. Using XPO1 inhibitor KPT-8602 and by siRNA-mediated knockdown, we confirmed the essential role of XPO1 in cell proliferation and growth transformation of KSHV-transformed cells, as well as cell lines of other types of cancer including gastric cancer and liver cancer. XPO1 inhibition induced cell cycle arrest and p53 activation, which depended on the formation of PML nuclear bodies. Furthermore, XPO1 induced relocalization of autophagy adaptor protein p62 (SQSTM1), recruiting p53 for activation in PML nuclear bodies. Our findings highlight a novel mechanism of p53 activation and identify XPO1 as a vulnerable target of cancer cells.
Project description:Nucleophosmin (NPM1) is a nucleolar protein and one of the most frequently mutated genes in acute myeloid leukemia (AML). In addition to the commonly detected frameshift mutations in exon12 (NPM1c), previous studies have identified NPM1 gene rearrangements leading to the expression of NPM1-fusion proteins in pediatric AML. However, whether the NPM1-fusions are indeed oncogenic and how the NPM1-fusions cause AML have been largely unknown. In this study, we investigated the subcellular localization and leukemogenic potential of two rare NPM1-fusion proteins, NPM1-MLF1 and NPM1-CCDC28A. NPM1-MLF1 is present in both the nucleus and cytoplasm and occasionally induces AML in the mouse transplantation assay (2/12). NPM1-CCDC28A localizes predominantly to the cytoplasm, immortalizes mouse bone marrow cells in vitro and efficiently (5/6) induces AML in vivo. Mechanistically, both NPM1-fusions bind to the HOX gene cluster and, like NPM1c, cause aberrant upregulation of HOX genes in cooperation with XPO1. The XPO1 inhibitor selinexor suppressed HOX activation and colony formation driven by the NPM1-fusions. Thus, our study provides experimental evidence that both NPM1-MLF1 and NPM1-CCDC28A are oncogenes with functions similar to NPM1c. Inhibition of XPO1 may be a promising strategy for the NPM1-rearranged AML.
Project description:Nucleophosmin (NPM1) is a nucleolar protein and one of the most frequently mutated genes in acute myeloid leukemia (AML). In addition to the commonly detected frameshift mutations in exon12 (NPM1c), previous studies have identified NPM1 gene rearrangements leading to the expression of NPM1-fusion proteins in pediatric AML. However, whether the NPM1-fusions are indeed oncogenic and how the NPM1-fusions cause AML have been largely unknown. In this study, we investigated the subcellular localization and leukemogenic potential of two rare NPM1-fusion proteins, NPM1-MLF1 and NPM1-CCDC28A. NPM1-MLF1 is present in both the nucleus and cytoplasm and occasionally induces AML in the mouse transplantation assay (2/12). NPM1-CCDC28A localizes predominantly to the cytoplasm, immortalizes mouse bone marrow cells in vitro and efficiently (5/6) induces AML in vivo. Mechanistically, both NPM1-fusions bind to the HOX gene cluster and, like NPM1c, cause aberrant upregulation of HOX genes in cooperation with XPO1. The XPO1 inhibitor selinexor suppressed HOX activation and colony formation driven by the NPM1-fusions. Thus, our study provides experimental evidence that both NPM1-MLF1 and NPM1-CCDC28A are oncogenes with functions similar to NPM1c. Inhibition of XPO1 may be a promising strategy for the NPM1-rearranged AML.
Project description:We assessed the chromatin localization of XPO1, different histone markers, and transcription factors associated with T cell activation with and without SP100030 treatment We used CUT&RUN sequencing as a lower-input (500,000 cells per sample), higher-sensitivity alternative to ChIP-Seq to assess chromatin binding of different factors
Project description:SF3B1 mutations are the most frequent spliceosomal alterations across cancers, yet no successful therapy exists to target this pathway. Previous findings from a phase 2 clinical trial of the XPO1 inhibitor selinexor in patients with high-risk myelodysplastic neoplasms (MDS) relapsed or refractory to hypomethylating agents (HMA) revealed increased activity in patients with SF3B1 mutations. XPO1 (Exportin-1) is responsible for the export of over 200 proteins, but also plays a role in the transport of multiple RNA species, including small nuclear RNAs (snRNAs), ribosomal RNAs (rRNAs), and select messenger RNAs (mRNAs) out of the nucleus. We therefore hypothesized that XPO1 inhibition perturbs RNA export and may preferentially affect SF3B1 mutants via altered splicing, given the role of XPO1 in exporting snRNAs, which form the catalytic portion of the spliceosome. To evaluate the mechanism underlying preferentially sensitivity of SF3B1-mutants to XPO1 inhibition, we performed nuclear and cytoplasmic fraction followed by RNA sequencing before and after XPO1 inhibition in SF3B1 wildtype and SF3B1 K666N cells (subcellular RNA-seq). Whole transcriptomic analysis of subcellular RNA-seq data revealed more nuclear retention of global RNA transcripts after XPO1 inhibition in the SF3B1 mutant cell line. Similarly, we performed subcellular RNA-seq for small RNAs and found snRNAs to be increased in the nucleus after XPO1 inhibition in the SF3B1 mutant cells. We then performed total cellular RNA sequencing to understand the effect of XPO1 inhibition on global RNA expression and RNA splicing. Differential gene expression analysis identified that XPO1 inhibition had the greatest effect on cell cycle in SF3B1 wildtype cells but in SF3B1-mutant cells differentiation pathways were more significantly affected. Alternative splicing analysis showed increased 3’ alternative splicing events in SF3B1 mutant after XPO1 inhibition. These results signify the mechanistic basis for preferential sensitivity of SF3B1 mutant cells to nuclear export inhibition arises through nuclear retention of spliceosomal snRNAs and select mRNAs that result in perturbation of differentiation pathways.
Project description:To investigate the cooperative function TFII-I and TRIM24 in the regulation of T cell activation regulated genes, we established Jurkat Tat cells in which TFII-I was depleted by shRNA and TRIM24 was knocked out by CRISPR-Cas9. We then performed gene expression profiling analysis using data obtained from RNA-seq of cell lines stimulated by PMA and Ionomycin.