Biology subjects

Pappin, D.

Publications and source records attributed to Pappin, D..

4 recordsLinked to original sources

bioRxiv2025

NOVEL SMALL-MOLECULE INHIBITORS OF THE PROTEIN KINASE DYRK: POTENTIAL THERAPEUTIC CANDIDATES IN CANCER

Dual-specificity tyrosine-regulated kinase 1A (DYRK1A) is crucial for normal brain development and its disruption has been linked to various cancers. DYRK1A drives glioblastoma (GBM) progression via stabilization of epidermal growth factor receptor (EGFR). Here we describe two, selective, benzothiazole-derived DYRK inhibitors, FC-2 and FC-3, obtained by structure-activity optimization of a natural product lead. Both compounds inhibit DYRK1A with nanomolar potency and display high selectivity across a kinase panel. The co-crystal structure of FC-3 with DYRK1A revealed ATP-competitive binding, with interactions at the hinge region and the DYRK-specific phenylalanine gatekeeper residue explaining target selectivity. Generation of inhibitor-resistant mutants confirmed DYRK1A as the primary cellular target. In GBM cell-models, FC-2 and FC-3 impaired neurosphere self-renewal, cell invasion, and EGFR stability, phenocopying DYRK1A loss. Both compounds crossed the blood-brain barrier and suppressed tumor growth, to prolong survival in intracranial xenografts. These findings identify FC-2 and FC-3 as selective small-molecule inhibitors of DYRK1A with potential therapeutic utility in GBM.

cancer biology↗

bioRxiv2025

Identification and Validation of an inhibitor of the protein kinases PIM and DYRK

Fermented wheat germ extract (FWGE), a nutraceutical with reported anticancer properties, contains numerous biologically active molecules, but its precise therapeutic constituents remain unclear. In this study, we identify and characterize a novel small-molecule inhibitor, CSH-4044, isolated from FWGE. Through preparative HPLC and structural elucidation via X-ray crystallography, CSH-4044 was revealed to be a unique benzothiazole compound. Kinase profiling demonstrated its high specificity toward the PIM and DYRK families of protein kinases. We determined the co-crystal structure of CSH-4044 bound to PIM1, revealing ATP-competitive binding, and critical hydrophobic and hydrogen-bonding interactions. A chemically synthesized version of CSH-4044 mirrored the activity of the natural product, confirming structural integrity and biological equivalence. Functionally, CSH-4044 suppressed PIM3-driven BAD phosphorylation in pancreatic cancer cells and reduced DYRK1A-mediated Tau phosphorylation in neuronal cells. Our findings position CSH-4044 as a promising lead for targeting PIM and DYRK families of kinases and highlight FWGE as a source of potential therapeutic compounds.

biochemistry↗

bioRxiv2023

Plasma cells in human pancreatic ductal adenocarcinoma secrete antibodies to self-antigens

Intratumoral B cell responses are associated with more favorable clinical outcomes in human pancreatic ductal adenocarcinoma (PDAC). However, the antigens driving these B cell responses are largely unknown. We sought to discover these antigens by using single-cell RNA sequencing (scRNA-Seq) and immunoglobulin (Ig) sequencing of tumor-infiltrating immune cells from seven primary PDAC samples. We identified activated T and B cell responses and evidence of germinal center reactions. Ig sequencing identified plasma cell (PC) clones expressing isotype-switched and hyper-mutated Igs, suggesting the occurrence of T cell-dependent B cell responses. We assessed the reactivity of 41 recombinant antibodies that represented the products of 235 PCs and 12 B cells toward multiple cell lines and PDAC tissues, and observed frequent staining of intracellular self-antigens. Three of these antigens were identified: the filamentous actin (F-actin), the nucleic protein, RUVBL2, and the mitochondrial protein, HSPD1. Antibody titers to F-actin and HSPD1 were elevated in the plasma of PDAC patients, and also detectable in healthy donors. Thus, PCs in PDAC produce auto-antibodies reacting with intracellular self-antigens, which may result from promotion of pre-existing, autoreactive B cell responses. These observations indicate that the chronic inflammatory microenvironment of PDAC can support the adaptive immune response.

cancer biology↗

bioRxiv2022

Translesion DNA synthesis polymerase kappa functions in the nucleolar stress response

DNA polymerase kappa (Pol{kappa}) has multiple cellular roles such as translesion DNA synthesis, replication of repetitive sequences and nucleotide excision repair. However, the mechanisms regulating Pol{kappa}s cellular activities are unknown. Since all polymerases insert the canonical deoxynucleotide triphosphates, it is difficult to determine which polymerase is active at a particular genomic site. To counter this difficulty, we utilized the selective Pol{kappa} substrate, N2-(4-ethynylbenyl)-2-deoxyguanosine (EBndG), as bait to capture proteins associated with Pol{kappa} synthesized DNA. Here we show that, Pol{kappa} is active in the nucleolus and Pol{kappa} synthesized DNA are enriched with nucleolar proteins. Exposure of cells to benzo[a]pyrene diol epoxide (BPDE) induced hallmarks of nucleolar stress, increased Pol{kappa} stability and nucleolar activity. Other agents that induce nucleolar stress such as mitomycin C, cisplatin and actinomycin D also increased Pol{kappa}s nucleolar activity. The Pol{kappa} activity was cell-cycle independent and dependent on PCNA ubiquitination. In addition, we identified that the expression and activity of Pol{kappa} is regulated by the polycomb complex protein Ring Finger Protein 2 (RNF2) and by poly(ADP)-ribose polymerase 1 (PARP1) catalyzed PARylation. This study provides insight into the novel role of Pol{kappa} in ribosomal RNA synthesis, in maintaining ribosomal DNA integrity after DNA damage thus protecting the cells from nucleolar stress.

molecular biology↗