Mukund Mehrotra

Platelet and osteoclast β3 integrins are critical for bone metastasis

Mice with a targeted deletion of β3 integrin were used to examine the process by which tumor cells metastasize and destroy bone. Injection of B16 melanoma cells into the left cardiac ventricle resulted in osteolytic bone metastasis in 74% of β3+/+ mice by 14 days. In contrast, only 4% of β3–/– mice developed bone lesions. Direct intratibial inoculation of tumor resulted in marrow replacement by tumor in β3–/– mice, but no associated trabecular bone resorption as seen inβ3+/+ mice. Bone marrow transplantation studies showed that susceptibility to bone metastasis was conferred by a bone marrow-derived cell. To dissect the roles of osteoclast and platelet β3 integrins in this model of bone metastasis, osteoclast-defective src–/– mice were used. Src-null mice were protected from tumor-associated bone destruction but were not protected from tumor cell metastasis to bone. In contrast, a highly specific platelet aggregation inhibitor of activated αIIbβ3 prevented B16 metastases. These data demonstrate a critical role for platelet αIIbβ3 in tumor entry into bone and suggest a mechanism by which antiplatelet therapy may be beneficial in preventing the metastasis of solid tumors.

Spirocyclic nonpeptide glycoprotein IIb–IIIa antagonists. Part 3: synthesis and SAR of potent and specific 2,8-diazaspiro[4.5]decanes

The synthesis and biological activity of analogues containing spiro piperidinylpyridine and pyrrolidinylpyridine templates are described. The potent activity of these compounds as platelet aggregation inhibitors demonstrates the utility of the spiro structures as central template for nonpeptide RGD mimics.

Spirocyclic nonpeptide glycoprotein IIb-IIIa antagonists. Part 1: design of potent and specific 3,9-diazaspiro[5.5]undecanes.

The synthesis and biological activity of novel glycoprotein IIb-IIla antagonists containing the 3,9-diazaspiro[5.5]undecane nucleus are described. The potent activity of these compounds as platelet aggregation inhibitors demonstrates the utility of the spirocyclic structures as a central template for nonpeptide RGD mimics.

Spirocyclic nonpeptide glycoprotein IIb–IIIa antagonists. Part 2: design of potent antagonists containing the 3-azaspiro[5.5]undec-9-yl template

Abstract The synthesis and biological activity of novel glycoprotein IIb–IIIa anatagonists containing 3-azaspiro[5.5]undec-9-yl nucleus are described. The potent activity of these compounds as platelet aggregation inhibitors demonstrates the utility of the monoazaspirocyclic structure as central template for nonpeptide RGD mimics.

α-Dicarbonyls as “non-charged” arginine-directed affinity labels. Novel synthetic routes to α-dicarbonyl analogs of the PP60c-src SH2 domain-targeted phosphopeptide Ac-Tyr(OPO3H2)-Glu-Glu-Ile-Glu

Abstract The phosphopeptide 1 is a potent inhibitor of pp60 c-src SH2 domain mediated phosphoprotein interactions (IC 50 ≤ 0.5 μM), but lacks cell permeability. The syntheses of its less charged analogs 2 and 3 are described, in which the arginine-binding phosphate group has been substituted with uncharged α-dicarbonyl moieties. The chemistry described here may be of general use for the synthesis of other α-dicarbonyl compounds.