Project description:In order to identify miRNAs involved in tumor development of DICER1 syndrome model mouse, next-generation sequencing analysis of RNA extracted from liver tissue was performed.
Project description:DICER1 syndrome is a tumor predisposition syndrome caused by familial genetic mutations in DICER1. Pathogenic variants of DICER1 have been discovered in many rare cancers, including cystic liver tumors. However, the molecular mechanisms underlying liver lesions induced by these variants remain unclear. In the present study, we sought to gain a better understanding of the pathogenesis of these variants by generating a mouse model of liver-specific DICER1 syndrome. The mouse model developed bile duct hyperplasia with fibrosis, similar to congenital hepatic fibrosis, as well as cystic liver tumors resembling those in Caroli's syndrome, intrahepatic cholangiocarcinoma, and hepatocellular carcinoma. Interestingly, the mouse model of DICER1 syndrome showed abnormal formation of primary cilia in the bile duct epithelium, which is a known cause of bile duct hyperplasia and cyst formation. These results indicated that DICER1 mutations contribute to cystic liver tumors by inducing defective primary cilia. The mouse model generated in this study will be useful for elucidating the potential mechanisms of tumorigenesis induced by DICER1 variants and for obtaining a comprehensive understanding of DICER1 syndrome.
Project description:The DICER1 gene is mutated in cancer, including Dicer1 syndrome, a rare tumour predisposition syndrome. Cancer-associated hotspots mutations have been reported in both catalytic domains of Dicer, and are predicted to disrupt miRNA processing activity. To understand these hotspot mutations in cancer development, we have generated cell lines harbouring single amino acid substitutions within either the RNAse IIIa (S1344L) and the RNAse IIIb (D1709N) domains of the endogenous Dicer1 gene. We show that both mutations result in a widespread loss of 5p miRNAs, but, unexpectedly, an increase in 3p passenger strands loading into Ago2. Similarities between both mutants can be explained as the S1344 residue is structurally also part of the RNase IIIb catalytical site. Functionally, we found that changes in the repertoire of miRNAs loaded into Ago2 result in altered gene expression, impacting critical pathways for cancer development, including metastatic potential. Our results indicate that inactivating the processing activity of Dicer does not result in genomic instability. Instead, mutations cause a specific upregulation of human endogenous retrovirus H (HERVH) and 3p miRNAs, which have the potential to be used as markers for Dicer1 syndrome tumours.
Project description:DICER1 syndrome predisposes children and young adults to tumor development across various organs. Most of these cancers are sarcomas, which uniquely express the RNase IIIb domain-deficient form of DICER1 and exhibit histological and molecular similarities regardless of their anatomical origins. To uncover their cellular origin and developmental hierarchy, we established a lineage-traceable genetically engineered mouse model allowing for controlled activation of Dicer1 mutations in Hic1+ mesenchymal stromal cells. This resulted in the development of renal tumors closely mirroring human DICER1 sarcoma histologically and molecularly. Spatial single-cell transcriptomics analysis revealed that a Hic1+Pdgfra+Mfap4+ fibroblastic progenitor population, corresponding to perivascular universal fibroblasts of steady-state kidneys, exhibits the capability to undergo rhabdomyoblastic differentiation or transition into proliferative sarcomatous cells. Investigation of patient samples identified analogous cell states and developmental trajectories. This study uncovers a fibroblastic origin for DICER1 sarcoma and provides a faithful model for future mechanistic and translational investigation.
Project description:DICER1 syndrome predisposes children and young adults to tumor development across various organs. Most of these cancers are sarcomas, which uniquely express the RNase IIIb domain-deficient form of DICER1 and exhibit histological and molecular similarities regardless of their anatomical origins. To uncover their cellular origin and developmental hierarchy, we established a lineage-traceable genetically engineered mouse model allowing for controlled activation of Dicer1 mutations in Hic1+ mesenchymal stromal cells. This resulted in the development of renal tumors closely mirroring human DICER1 sarcoma histologically and molecularly. Spatial single-cell transcriptomics analysis revealed that a Hic1+Pdgfra+Dpt+Pi16+ fibroblastic progenitor population, corresponding to universal fibroblasts of steady-state kidneys, exhibits the capability to undergo rhabdomyoblastic differentiation or transition into proliferative sarcomatous cells. Investigation of patient samples identified analogous cell states and developmental trajectories. This study uncovers a fibroblastic origin for DICER1 sarcoma and provides a faithful model for future mechanistic and translational investigation.
Project description:DICER1 syndrome predisposes children and young adults to tumor development across various organs. Most of these cancers are sarcomas, which uniquely express the RNase IIIb domain-deficient form of DICER1 and exhibit histological and molecular similarities regardless of their anatomical origins. To uncover their cellular origin and developmental hierarchy, we established a lineage-traceable genetically engineered mouse model allowing for controlled activation of Dicer1 mutations in Hic1+ mesenchymal stromal cells. This resulted in the development of renal tumors closely mirroring human DICER1 sarcoma histologically and molecularly. Spatial single-cell transcriptomics analysis revealed that a Hic1+Pdgfra+Mfap4+ fibroblastic progenitor population, corresponding to perivascular universal fibroblasts of steady-state kidneys, exhibits the capability to undergo rhabdomyoblastic differentiation or transition into proliferative sarcomatous cells. Investigation of patient samples identified analogous cell states and developmental trajectories. This study uncovers a fibroblastic origin for DICER1 sarcoma and provides a faithful model for future mechanistic and translational investigation.
Project description:The DICER1 gene is mutated in cancer, including Dicer1 syndrome, a rare tumour predisposition syndrome. Cancer-associated hotspots mutations have been reported in both catalytic domains of Dicer, and are predicted to disrupt miRNA processing activity. To understand these hotspot mutations in cancer development, we have generated cell lines harbouring single amino acid substitutions within either the RNAse IIIa (S1344L) and the RNAse IIIb (D1709N) domains of the endogenous Dicer1 gene. We show that both mutations result in a widespread loss of 5p miRNAs, but, unexpectedly, an increase in 3p passenger strands loading into Ago2. Similarities between both mutants can be explained as the S1344 residue is structurally also part of the RNase IIIb catalytical site. Functionally, we found that changes in the repertoire of miRNAs loaded into Ago2 result in altered gene expression, impacting critical pathways for cancer development, including metastatic potential. Our results indicate that inactivating the processing activity of Dicer does not result in genomic instability. Instead, mutations cause a specific upregulation of human endogenous retrovirus H (HERVH) and 3p miRNAs, which have the potential to be used as markers for Dicer1 syndrome tumours.
Project description:We developed a genetically engineered conditional compound heterozygous Dicer1 mouse strain that fully recapitulates the bi-allelic mutations of DICER1 in DICER1 syndrome-associated cancers. Embryonic activation of bi-allelic Dicer1 mutations, driven by the anti-Müllerian hormone receptor 2 (Amhr2)-driven Cre strain (Amhr2+/cre), drove cancer development from oviduct. Small RNA sequencing was performed to compare the microRNA expression profiles between tumor and normal oviduct.
Project description:The DICER1 gene is mutated in cancer, including Dicer1 syndrome, a rare tumour predisposition syndrome. Cancer-associated hotspots mutations have been reported in both catalytic domains of Dicer, and are predicted to disrupt miRNA processing activity. To understand these hotspot mutations in cancer development, we have generated cell lines harbouring single amino acid substitutions within either the RNAse IIIa (S1344L) and the RNAse IIIb (D1709N) domains of the endogenous Dicer1 gene. We show that both mutations result in a widespread loss of 5p miRNAs, but, unexpectedly, an increase in 3p passenger strands loading into Ago2. Similarities between both mutants can be explained as the S1344 residue is structurally also part of the RNase IIIb catalytical site. Functionally, we found that changes in the repertoire of miRNAs loaded into Ago2 result in altered gene expression, impacting critical pathways for cancer development, including metastatic potential. Our results indicate that inactivating the processing activity of Dicer does not result in genomic instability. Instead, mutations cause a specific upregulation of human endogenous retrovirus H (HERVH) and 3p miRNAs, which have the potential to be used as markers for Dicer1 syndrome tumours.