Project description:The E3 SUMO ligase PIAS2 is expressed at high levels in differentiated papillary thyroid carcinomas but at low levels in anaplastic thyroid carcinomas (ATC), an undifferentiated cancer with very high mortality. Double-stranded RNA–directed RNA interference (dsRNAi) targeting the PIAS2 isoform beta (PIAS2b) inhibits growth of ATC cell lines and patient primary cultures in vitro and orthotopic patient-derived xenografts (oPDX) in vivo, but not of thyroid cell lines or non-anaplastic primary thyroid cultures (differentiated carcinoma, benign lesions, or normal). PIAS2b-dsRNAi also has an anti-cancer effect on other anaplastic human cancers (pancreas, lung, and gastric). Mechanistically, PIAS2b is required for proper mitotic spindle and centrosome assembly, and it is a dosage-sensitive protein in ATC. Strikingly, PIAS2b-dsRNAi induces mitotic catastrophe at prophase. High-throughput proteomics revealed the proteasome (PSMC5) and spindle cytoskeleton as direct targets of PIAS2b SUMOylation at mitotic initiation. PIAS2b-dsRNAi is a promising therapy for ATC and other aggressive anaplastic cancers.
Project description:BACKGROUND. Poorly-differentiated (PDTC) and anaplastic (ATC) thyroid cancers are rare and frequently lethal tumors, which so far have not been subjected to comprehensive genetic characterization. METHODS. We performed next generation sequencing of 341 cancer genes in 117 PDTCs and ATCs, and a transcriptomic analysis of a representative subset of 37 tumors. Results were analyzed in the context of The Cancer Genome Atlas (TCGA) study of papillary thyroid cancers (PTC). RESULTS. ATCs have a greater mutation burden than PDTCs, and higher mutation frequency of TP53, TERT promoter, PI3K/AKT/mTOR pathway effectors, SWI/SNF subunits and histone methyltransferases. BRAF and RAS are the predominant drivers, and dictate remarkably distinct tropism for nodal vs. distant metastases in PDTC. RAS and BRAF sharply distinguish between PDTCs defined by the Turin (PDTC-Turin) vs. MSKCC (PDTC-MSK) criteria, respectively. Mutations of EIF1AX, a component of the translational preinitiation complex, are markedly enriched in PDTCs and ATCs, and have a striking pattern of co-occurrence with RAS. TERT promoter mutations are rare and subclonal in PTCs, whereas they are clonal and highly prevalent in advanced cancers. Application of the TCGA-derived BRAF-RAS score (a measure of MAPK transcriptional output) shows a preserved relationship with BRAF/RAS mutation in PDTCs, whereas ATCs are BRAF-like irrespective of driver mutation. CONCLUSIONS. These data support a model of tumorigenesis whereby PDTCs and ATCs arise from well-differentiated tumors through the accumulation of key additional genetic abnormalities, many of which have prognostic and possible therapeutic relevance. The widespread genomic disruptions in ATC compared to PDTC underscore their greater virulence and higher mortality. 37 tumor specimens, including 17 poorly-differentiated and 20 anaplastic thyroid cancers were expression-profiled with Affymetrix U133 plus 2.0 array
Project description:Molecular characteristics of anaplastic thyroid cancer (ATC) and advanced differentiated thyroid cancers (DTCs) have not been fully elucidated. In this study, we applied various types of massively-parallel sequencing technology to 113 advanced TCs, including 27 ATCs and 86 advanced DTCs, to reveal their genomic and transcriptomic characteristics.
Project description:Anaplastic thyroid carcinoma (ATC) is the most aggressive form of thyroid cancer, and often derives from pre-existing well-differentiated tumors. We have engineered the first mouse model of ATC by combining in the mouse thyroid follicular cells two molecular hallmarks of human ATC: activation of PI3K (via Pten deletion) and inactivation of p53. By 9 months of age, over 75% of the compound mutant mice develop aggressive, undifferentiated thyroid tumors that evolve from pre-existing follicular hyperplasia and carcinoma. These tumors display all the features of their human counterpart, including pleomorphism, epithelial-mesenchymal transition, aneuploidy, local invasion and distant metastases. We have performed expression profiling of thyroids from control, single mutants, compound mutants, follicular tumors from Pten-/- mice, and anaplastic tumors from Pten, p53-/- mice.