Immunoevolution of mouse pancreatic organoid isografts from preinvasive to metastatic disease

Pancreatic ductal adenocarcinoma (PDA) has a highly immunosuppressive microenvironment, which is contributed by the complex interaction between cancer cells and a heterogeneous population of stromal cells. Therefore, facile and trackable models are needed for integrative and dynamic interrogation of cancer-stroma interaction. Here, we tracked the immunoevolution of PDA in a genetically-defined transplantable model of mouse pancreatic tumour organoids that recapitulates the progression of the disease from early preinvasive lesions to metastatic carcinomas. We demonstrated that organoid-derived isografts (ODI) can be used as a biological source of biomarkers (NT5E, TGFB1, FN1, and ITGA5) of aggressive molecular subtypes of human PDA. In ODI, infiltration from leukocytes is an early event during progression of the disease as observed for autochthonous models. Neoplastic progression was associated to accumulation of Maf+ macrophages, which inversely correlated with CD8+ T cells infiltration. Consistently, levels of MAF were enriched in human PDA subtypes characterized by abundance of macrophage-related transcripts and indicated poor patients' survival. Density of MAF+ macrophages was higher in human PDA tissues compared to preinvasive lesions. Our results suggest that ODIs represent a suitable system for genotypic-immunophenotypic studies and support the hypothesis of MAF+ macrophages as a prominent immunosuppressive population in PDA

Loss of FGFR4 promotes the malignant phenotype of PDAC

Transcriptomic analyses of pancreatic ductal adenocarcinoma (PDAC) have identified two major epithelial subtypes with distinct biology and clinical behaviours. Here, we aimed to clarify the role of FGFR1 and FGFR4 in the definition of aggressive PDAC phenotypes. We found that the expression of FGFR4 is exclusively detected in epithelial cells, significantly elevated in the classical PDAC subtype, and associates with better outcomes. In highly aggressive basal-like/squamous PDAC, reduced FGFR4 expression aligns with hypermethylation of the gene and lower levels of histone marks associated with active transcription in its regulatory regions. Conversely, FGFR1 has more promiscuous expression in both normal and malignant pancreatic tissues and is strongly associated with the EMT phenotype but not with the basal-like cell lineage. Regardless of the genetic background, the increased proliferation of FGFR4-depleted PDAC cells correlates with hyperactivation of the mTORC1 pathway both in vitro and in vivo. Downregulation of FGFR4 in classical cell lines invariably leads to the enrichment of basal-like/squamous gene programs and is associated with either partial or full switch of phenotype. In sum, we show that endogenous levels of FGFR4 limit the malignant phenotype of PDAC cells. Finally, we propose FGFR4 as a valuable marker for the stratification of PDAC patients

Reactivity and Mechanistic Studies of Stereocontrol for Ziegler—Natta Polymerization Utilizing Doubly-Silylene Bridged Group 3 and Group 4 Metalocenes

A family of zirconocene, yttrocene, and scandocene complexes have been prepared utilizing an easily modified doubly bridged ligand array, (1,2-SiMe_2)_2{η^5-C_5H_2-4-R}{η^5-C_5H-3,5-CHMe_2)_2}, developed in our laboratories. Variations in ligand array substitution and metal center provide complexes that exhibit a range of stereoselectivities and activities in α-olefin polymerizations. A series of C_(s-) and C_(1-) symmetric metallocenes have been utilized for the preparation of polypropylene and polypentene under various polymerization conditions. Analysis of the resulting polymer microstructures has provided valuable information about the factors that dictate syndiospecificity, as well as common error forming mechanisms for these systems

Rhenium nitrosyl complexes for hydrogenations and hydrosilylations

The tris(acetonitrile)dibromonitrosylrhenium(I) compound (1a) was obtained by reduction of the paramagnetic [NMe4](2)[Re(NO)Br-5] salt with Zn in MeCN. Subsequent reaction of 1a with THF produced the THF derivative [Re(NO)(THF)(MeCN)(2)Br-2] (1b). Reaction of 1b with PiPr(3), Pcy(3), or P(p-tolyl)(3) yielded bis(acetonitrile)-cis-dibromo(nitrosyl)-trans-bis(phosphine)rfienium complexes (R = iPr 2a, cy 2b, p-tolyl 2c). Treatment of 2a,b with excess NaBH4 produced the known borohydride complexes [Re(H)(eta(2)-BH4)(NO)(PR3)(2)] (R = iPr 3a, cy 3b). Replacement of the BH3 moiety of 3a,b in THF by ethylene (I bar) produced the dihydride complexes [Re(H)(2)(eta(2)-C2H4)(NO)(PR3)(2)] (4) (R = iPr a, cy b). Protonation of 4a,b with HBF4 center dot OEt2 afforded H-2 and the monohydrido tetrafluoroborato species [Re(H)(NO)(PR3)(2)(eta(2)-C2H4)(BF4)] (R = iPr 5a, cy 5b). X-ray diffraction studies were carried out on 1a, 2b,c, and 5b. Complexes 4a,b are catalytically active in olefin, imine, and ketone hydrogenations and in olefin and ketone hydrosilylations, as well as in the scrambling of H-2/D-2 to give HD under mild conditions