Hypoxia-activated neuropeptide Y/Y5 receptor/RhoA pathway triggers chromosomal instability and bone metastasis in Ewing sarcoma.

Adverse prognosis in Ewing sarcoma (ES) is associated with the presence of metastases, particularly in bone, tumor hypoxia and chromosomal instability (CIN). Yet, a mechanistic link between these factors remains unknown. We demonstrate that in ES, tumor hypoxia selectively exacerbates bone metastasis. This process is triggered by hypoxia-induced stimulation of the neuropeptide Y (NPY)/Y5 receptor (Y5R) pathway, which leads to RhoA over-activation and cytokinesis failure. These mitotic defects result in the formation of polyploid ES cells, the progeny of which exhibit high CIN, an ability to invade and colonize bone, and a resistance to chemotherapy. Blocking Y5R in hypoxic ES tumors prevents polyploidization and bone metastasis. Our findings provide evidence for the role of the hypoxia-inducible NPY/Y5R/RhoA axis in promoting genomic changes and subsequent osseous dissemination in ES, and suggest that targeting this pathway may prevent CIN and disease progression in ES and other cancers rich in NPY and Y5R.

Neuropeptide Y/Y5 Receptor Pathway Stimulates Neuroblastoma Cell Motility Through RhoA Activation.

Neuropeptide Y (NPY) has been implicated in the regulation of cellular motility under various physiological and pathological conditions, including cancer dissemination. Yet, the exact signaling pathways leading to these effects remain unknown. In a pediatric malignancy, neuroblastoma (NB), high NPY release from tumor tissue associates with metastatic disease. Here, we have shown that NPY stimulates NB cell motility and invasiveness and acts as a chemotactic factor for NB cells. We have also identified the Y5 receptor (Y5R) as the main NPY receptor mediating these actions. In NB tissues and cell cultures, Y5R is highly expressed in migratory cells and accumulates in regions of high RhoA activity and dynamic cytoskeleton remodeling. Y5R stimulation activates RhoA and results in Y5R/RhoA-GTP interactions, as shown by pull-down and proximity ligation assays, respectively. This is the first demonstration of the role for the NPY/Y5R axis in RhoA activation and the subsequent cytoskeleton remodeling facilitating cell movement. These findings implicate Y5R as a target in anti-metastatic therapies for NB and other cancers expressing this receptor.

Highly enantioselective synthesis of functionalized azepino[1,2-a]indoles via NHC-catalyzed [3+4] annulation.

The enantioselective [3+4] annulation of 3-formylindol-2-methyl-malonates with 2-bromoenals catalyzed by NHCs is described to afford functionalized azepino[1,2-a]indoles in high yields with excellent enantioselectivities. This method, in which the 3-formyl group in indoles acts as a necessary mediating group, provided cycloaddition products under mild conditions.

Oxidative NHC catalysis: direct activation of ß sp3 carbons of saturated acid chlorides.

The first activation of saturated acid chlorides by oxidative N-heterocyclic carbene catalysis has been successfully utilized to synthesize enantio-enriched spirooxindole lactones and δ-lactones. The reaction involves the transformation of the ß sp3 carbon of saturated acid chlorides into an electrophilic carbon as a key step. The product was obtained in excellent yield and stereoselectivity.

Stereoselective Synthesis of Functionalized Tetrahydro-1H-1,2-diazepines by N-Heterocyclic Carbene-Catalyzed [3 + 4] Annulation.

An efficient N-heterocyclic carbene (NHC)-catalyzed asymmetric [3 + 4] annulation reaction of N-Ts hydrazones with 2-bromoenals has been developed. A series of functionalized tetrahydro-1H-1,2-diazepines with two consecutive stereocenters was obtained using NHCs as the catalyst in good yields with excellent diastereo- and enantioselectivities.

Highly stereoselective synthesis of functionalized pyrrolo[3,2-c]quinolines via N-heterocyclic carbene catalyzed cascade sequence.

An N-heterocyclic carbene-catalyzed stereoselective Michael-Mannich-lactamization cascade reaction of tosyl-protected o-amino aromatic aldimines and 2-bromoenals for the construction of functionalized pyrrolo[3,2-c]quinolines with three consecutive stereocenters was achieved in good yields with excellent diastereo- and enantioselectivities.

An unusual 1,2-aryl shift in palladium-catalyzed cross-coupling ethoxycarbonylation of arylboronic acids with α-iminoesters.

The Pd-catalyzed cross-coupling ethoxycarbonylation of aryl boronic acids with N-aryl-α-iminoesters affords aryl carboxylic esters via carbonyl-imino σ bond cleavage. This unprecedented mode of reaction allows regioselective installation of the ethoxycarbonyl group into target molecules. Mechanism studies have revealed that an unusual 1,2-aryl shift process is involved in the transformation.