RESUMO
Splicing modulation is a promising treatment strategy pursued to date only in splicing factor-mutant cancers; however, its therapeutic potential is poorly understood outside of this context. Like splicing factors, genes encoding components of the cohesin complex are frequently mutated in cancer, including myelodysplastic syndromes (MDS) and secondary acute myeloid leukemia (AML), where they are associated with poor outcomes. Here, we showed that cohesin mutations are biomarkers of sensitivity to drugs targeting the splicing factor 3B subunit 1 (SF3B1) H3B-8800 and E-7107. We identified drug-induced alterations in splicing, and corresponding reduced gene expression, of a number of DNA repair genes, including BRCA1 and BRCA2, as the mechanism underlying this sensitivity in cell line models, primary patient samples and patient-derived xenograft (PDX) models of AML. We found that DNA damage repair genes are particularly sensitive to exon skipping induced by SF3B1 modulators due to their long length and large number of exons per transcript. Furthermore, we demonstrated that treatment of cohesin-mutant cells with SF3B1 modulators not only resulted in impaired DNA damage response and accumulation of DNA damage, but it sensitized cells to subsequent killing by poly(ADP-ribose) polymerase (PARP) inhibitors and chemotherapy and led to improved overall survival of PDX models of cohesin-mutant AML in vivo. Our findings expand the potential therapeutic benefits of SF3B1 splicing modulators to include cohesin-mutant MDS and AML.
Assuntos
Leucemia Mieloide Aguda , Síndromes Mielodisplásicas , Humanos , Coesinas , Síndromes Mielodisplásicas/tratamento farmacológico , Síndromes Mielodisplásicas/genética , Síndromes Mielodisplásicas/metabolismo , Splicing de RNA , Fatores de Processamento de RNA/genética , Mutação/genética , Fatores de Transcrição/metabolismo , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , Reparo do DNA/genética , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Dano ao DNARESUMO
The glandular stomach is composed of two regenerative compartments termed corpus and antrum, and our understanding of the transcriptional networks that maintain these tissues is incomplete. Here we show that cell types with equivalent functional roles in the corpus and antrum share similar transcriptional states including the poorly characterized stem cells of the isthmus region. To further study the isthmus, we developed a monolayer two-dimensional (2D) culture system that is continually maintained by Wnt-responsive isthmus-like cells capable of differentiating into several gastric cell types. Importantly, 2D cultures can be converted into conventional three-dimensional organoids, modelling the plasticity of gastric epithelial cells in vivo. Finally, we utilized the 2D culture system to show that Sox2 is both necessary and sufficient to generate enterochromaffin cells. Together, our data provide important insights into gastric homeostasis, establish a tractable culture system to capture isthmus cells and uncover a role for Sox2 in enterochromaffin cells.
Assuntos
Mucosa Gástrica , Estômago , Mucosa Gástrica/metabolismo , Diferenciação Celular , Células-Tronco/metabolismo , HomeostaseRESUMO
The cohesin complex plays an essential role in chromosome maintenance and transcriptional regulation. Recurrent somatic mutations in the cohesin complex are frequent genetic drivers in cancer, including myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Here, using genetic dependency screens of stromal antigen 2-mutant (STAG2-mutant) AML, we identified DNA damage repair and replication as genetic dependencies in cohesin-mutant cells. We demonstrated increased levels of DNA damage and sensitivity of cohesin-mutant cells to poly(ADP-ribose) polymerase (PARP) inhibition. We developed a mouse model of MDS in which Stag2 mutations arose as clonal secondary lesions in the background of clonal hematopoiesis driven by tet methylcytosine dioxygenase 2 (Tet2) mutations and demonstrated selective depletion of cohesin-mutant cells with PARP inhibition in vivo. Finally, we demonstrated a shift from STAG2- to STAG1-containing cohesin complexes in cohesin-mutant cells, which was associated with longer DNA loop extrusion, more intermixing of chromatin compartments, and increased interaction with PARP and replication protein A complex. Our findings inform the biology and therapeutic opportunities for cohesin-mutant malignancies.
Assuntos
Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Reparo do DNA/genética , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Mutação , Síndromes Mielodisplásicas/genética , Síndromes Mielodisplásicas/metabolismo , Animais , Linhagem Celular Tumoral , Cromatina/genética , Cromatina/metabolismo , Dano ao DNA , Modelos Animais de Doenças , Feminino , Humanos , Células K562 , Leucemia Mieloide Aguda/tratamento farmacológico , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Camundongos Mutantes , Camundongos SCID , Camundongos Transgênicos , Síndromes Mielodisplásicas/tratamento farmacológico , Proteínas Nucleares/genética , Ftalazinas/farmacologia , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Células U937 , Ensaios Antitumorais Modelo de Xenoenxerto , CoesinasRESUMO
The epithelial compartment of the mammary gland contains basal and luminal cell lineages, as well as stem and progenitor cells that reside upstream in the differentiation hierarchy. Stem and progenitor cell differentiation is regulated to maintain adult tissue and mediate expansion during pregnancy and lactation. The genetic factors that regulate the transition of cells between differentiation states remain incompletely understood. Here, we present a genome-scale method to discover genes driving cell-state specification. Applying this method, we identify a transcription factor, BCL11B, which drives stem cell self-renewal in vitro, by inhibiting differentiation into the basal lineage. To validate BCL11B's functional role, we use two-dimensional colony-forming and three-dimensional tissue differentiation assays to assess the lineage differentiation potential and functional abilities of primary human mammary cells. These findings show that BCL11B regulates mammary cell differentiation and demonstrate the utility of our proposed genome-scale strategy for identifying lineage regulators in mammalian tissues.
