Structure-activity relationship studies and design of a PTPN22 inhibitor with enhanced isozyme selectivity and cellular efficacy.

Protein tyrosine phosphatase non-receptor type 22 (PTPN22) lies downstream of the T cell receptor (TCR) and attenuates T cell signaling by dephosphorylating key effector proteins such as LCK, Zap70, and the intracellular region of the TCR. Recent evidence implicates PTPN22 as an exciting target for enabling immunotherapeutic efficacy against cancer. We carried out structural optimization of a benzofuran salicylic acid-based orthosteric PTPN22 inhibitor 8b, using a combination of crystal structure analysis, synthesis, matched molecular pairs analysis, and biochemical and cell-based assays.

Discovery and evaluation of novel SHIP-1 inhibitors.

Src Homology 2-containing Inositol 5'-Phosphatase-1 (SHIP-1), encoded by INPP5D, has been identified as an Alzheimer's disease (AD) risk-associated gene through recent genetic and epigenetic studies. SHIP-1 confers AD risk by inhibiting the TREM2 cascade and reducing beneficial microglial cellular processes, including phagocytosis. While several small molecules have been reported to modulate SHIP-1 activity, their limited selectivity and efficacy in advanced models restricted their potential as therapeutic agents or probes for biological studies.

Development of Novel Phosphonodifluoromethyl-Containing Phosphotyrosine Mimetics and a First-In-Class, Potent, Selective, and Bioavailable Inhibitor of Human CDC14 Phosphatases.

Together with protein tyrosine kinases, protein tyrosine phosphatases (PTPs) control protein tyrosine phosphorylation and regulate numerous cellular functions. Dysregulated PTP activity is associated with the onset of multiple human diseases. Nevertheless, understanding of the physiological function and disease biology of most PTPs remains limited, largely due to the lack of PTP-specific chemical probes.

Drugging Protein Tyrosine Phosphatases through Targeted Protein Degradation.

Protein tyrosine phosphatases (PTPs) are an important class of enzymes that regulate protein tyrosine phosphorylation levels of a large variety of proteins in cells. Anomalies in protein tyrosine phosphorylation have been associated with the development of numerous human diseases, leading to a heightened interest in PTPs as promising targets for drug development. However, therapeutic targeting of PTPs has faced skepticism about their druggability.

Inhibition of PRL2 Upregulates PTEN and Attenuates Tumor Growth in Tp53-deficient Sarcoma and Lymphoma Mouse Models.

Unlabelled: The phosphatases of regenerating liver (PRL) are oncogenic when overexpressed. We previously found that PRL2 deletion increases PTEN, decreases Akt activity, and suppresses tumor development in a partial Pten-deficient mouse model. The current study aims to further establish the mechanism of PTEN regulation by PRL2 and expand the therapeutic potential for PTEN augmentation mediated by PRL2 inhibition in cancers initiated without PTEN alteration.

Discovery of a selective TC-PTP degrader for cancer immunotherapy.

T-cell protein tyrosine phosphatase (TC-PTP), encoded by PTPN2, has emerged as a promising target for cancer immunotherapy. TC-PTP deletion in B16 melanoma cells promotes tumor cell antigen presentation, while loss of TC-PTP in T-cells enhances T-cell receptor (TCR) signaling and stimulates cell proliferation and activation. Therefore, there is keen interest in developing TC-PTP inhibitors as novel immunotherapeutic agents.

Discovery of a SHP2 Degrader with In Vivo Anti-Tumor Activity.

Src homology 2 domain-containing phosphatase 2 (SHP2) is an attractive target for cancer therapy due to its multifaceted roles in both tumor and immune cells. Herein, we designed and synthesized a novel series of proteolysis targeting chimeras (PROTACs) using a SHP2 allosteric inhibitor as warhead, with the goal of achieving SHP2 degradation both inside the cell and in vivo. Among these molecules, compound induces efficient degradation of SHP2 (DC = 35.

PRL2 Phosphatase Promotes Oncogenic KIT Signaling in Leukemia Cells through Modulating CBL Phosphorylation.

Unlabelled: Receptor tyrosine kinase KIT is frequently activated in acute myeloid leukemia (AML). While high PRL2 (PTP4A2) expression is correlated with activation of SCF/KIT signaling in AML, the underlying mechanisms are not fully understood. We discovered that inhibition of PRL2 significantly reduces the burden of oncogenic KIT-driven leukemia and extends leukemic mice survival.

Small Molecule Degraders of Protein Tyrosine Phosphatase 1B and T-Cell Protein Tyrosine Phosphatase for Cancer Immunotherapy.

Protein tyrosine phosphatase 1B (PTP1B) and T-cell protein tyrosine phosphatase (TC-PTP) play non-redundant negative regulatory roles in T-cell activation, tumor antigen presentation, insulin and leptin signaling, and are potential targets for several therapeutic applications. Here, we report the development of a highly potent and selective small molecule degrader DU-14 for both PTP1B and TC-PTP. DU-14 mediated PTP1B and TC-PTP degradation requires both target protein(s) and VHL E3 ligase engagement and is also ubiquitination- and proteasome-dependent.

Tumor Cell-Autonomous SHP2 Contributes to Immune Suppression in Metastatic Breast Cancer.

Unlabelled: SH2 containing protein tyrosine phosphatase-2 (SHP2) is recognized as a druggable oncogenic phosphatase that is expressed in both tumor cells and immune cells. How tumor cell-autonomous SHP2 contributes to an immunosuppressive tumor microenvironment (TME) and therapeutic failure of immune checkpoint blockades in metastatic breast cancer (MBC) is not fully understood. Herein, we utilized systemic SHP2 inhibition and inducible genetic depletion of SHP2 to investigate immune reprogramming during SHP2 targeting.

Driving axon regeneration by orchestrating neuronal and non-neuronal innate immune responses via the IFNγ-cGAS-STING axis.

The coordination mechanism of neural innate immune responses for axon regeneration is not well understood. Here, we showed that neuronal deletion of protein tyrosine phosphatase non-receptor type 2 sustains the IFNγ-STAT1 activity in retinal ganglion cells (RGCs) to promote axon regeneration after injury, independent of mTOR or STAT3. DNA-damage-induced cGAMP synthase (cGAS)-stimulator of interferon genes (STINGs) activation is the functional downstream signaling.

PRL2 phosphatase enhances oncogenic FLT3 signaling via dephosphorylation of the E3 ubiquitin ligase CBL at tyrosine 371.

Acute myeloid leukemia (AML) is an aggressive blood cancer with poor prognosis. FMS-like tyrosine kinase receptor-3 (FLT3) is one of the major oncogenic receptor tyrosine kinases aberrantly activated in AML. Although protein tyrosine phosphatase PRL2 is highly expressed in some subtypes of AML compared with normal human hematopoietic stem and progenitor cells, the mechanisms by which PRL2 promotes leukemogenesis are largely unknown.

The Q61H mutation decouples KRAS from upstream regulation and renders cancer cells resistant to SHP2 inhibitors.

Cancer cells bearing distinct KRAS mutations exhibit variable sensitivity to SHP2 inhibitors (SHP2i). Here we show that cells harboring KRAS Q61H are uniquely resistant to SHP2i, and investigate the underlying mechanisms using biophysics, molecular dynamics, and cell-based approaches. Q61H mutation impairs intrinsic and GAP-mediated GTP hydrolysis, and impedes activation by SOS1, but does not alter tyrosyl phosphorylation.

SHP2 is a multifunctional therapeutic target in drug resistant metastatic breast cancer.

Metastatic breast cancer (MBC) is an extremely recalcitrant disease capable of bypassing current targeted therapies via engagement of several growth promoting pathways. SH2 containing protein tyrosine phosphatase-2 (SHP2) is an oncogenic phosphatase known to facilitate growth and survival signaling downstream of numerous receptor inputs. Herein, we used inducible genetic depletion and two distinct pharmacological inhibitors to investigate the therapeutic potential of targeting SHP2 in MBC.

Tyrosyl phosphorylation of KRAS stalls GTPase cycle via alteration of switch I and II conformation.

Deregulation of the RAS GTPase cycle due to mutations in the three RAS genes is commonly associated with cancer development. Protein tyrosine phosphatase SHP2 promotes RAF-to-MAPK signaling pathway and is an essential factor in RAS-driven oncogenesis. Despite the emergence of SHP2 inhibitors for the treatment of cancers harbouring mutant KRAS, the mechanism underlying SHP2 activation of KRAS signaling remains unclear.

SHP2 phosphatase as a novel therapeutic target for melanoma treatment.

Melanoma ranks among the most aggressive and deadly human cancers. Although a number of targeted therapies are available, they are effective only in a subset of patients and the emergence of drug resistance often reduces durable responses. Thus there is an urgent need to identify new therapeutic targets and develop more potent pharmacological agents for melanoma treatment.

Copper-promoted site-selective carbonylation of sp and sp C-H bonds with nitromethane.

Copper-promoted direct carbonylation of unactivated sp C-H and aromatic sp C-H bonds of amides was developed using nitromethane as a novel carbonyl source. The sp C-H functionalization showed high site-selectivity by favoring the C-H bonds of α-methyl groups. The sp C-H carbonylation featured high regioselectivity and good functional group compatibility.

Palladium-Catalyzed Site-Selective Fluorination of Unactivated C(sp(3))-H Bonds.

The transition-metal-catalyzed direct C-H bond fluorination is an attractive synthetic tool toward the preparation of organofluorines. While many methods exist for the direct sp(3) C-H functionalization, site-selective fluorination of unactivated sp(3) carbons remains a challenge. Direct, highly site-selective and diastereoselective fluorination of aliphatic amides via a palladium-catalyzed bidentate ligand-directed C-H bond functionalization process on unactivated sp(3) carbons is reported.

Rhodium-catalyzed direct synthesis of unprotected NH-sulfoximines from sulfoxides.

A novel rhodium-catalyzed imination of sulfoxides using O-(2,4-dinitrophenyl)hydroxylamine is developed under mild conditions with good functional group tolerance. This method provides an efficient access to free NH-sulfoximines, an important structural unit in a variety of biologically active compounds.

Palladium-catalyzed chemoselective decarboxylative ortho acylation of benzoic acids with α-oxocarboxylic acids.

Palladium-catalyzed chemoselective decarboxylative cross coupling of benzoic acids with α-oxocarboxylic acids was realized via an arene sp(2) C-H functionalization process. This work represents the first example of transition-metal-catalyzed cross-coupling reactions with two acids acting in different roles. The synthetic utility of this method was confirmed by the synthesis of pitofenone, an antispasmodic used in the combined drug Spasmalgon.

Margareta Mikkelsen.

Margareta Mikkelsen, a well-known Danish cytogeneticist, started to research autosome aberrations in 1959 and built the first chromosome laboratory at the University of Copenhagen with Anders Frøland. In 1968, she developed a fully functional chromosome laboratory from scratch at the John F. Kennedy Institute (JFKI).