Discovery of a Novel, Potent, and Src Family-selective Tyrosine Kinase Inhibitor

Abstract

Here, we have studied the activity of a novel proteintyrosine kinase inhibitor that is selective for the Src family of tyrosine kinases. We have focused our study on the effects of this compound on T cell receptor-induced T cell activation, a process dependent on the activity of the Src kinases Lck and FynT. This compound is a nanomolar inhibitor of Lck and FynT, inhibits anti-CD3-induced protein-tyrosine kinase activity in T cells, demonstrates selectivity for Lck and FynT over ZAP-70, and preferentially inhibits T cell receptor-dependent anti-CD3-induced T cell proliferation over non-T cell receptor-dependent phorbol 12-myristate 13-acetate/interleukin-2 (IL-2)-induced T cell proliferation. Interestingly, this compound selectively inhibits the induction of the IL-2 gene, but not the granulocyte-macrophage colonystimulating factor or IL-2 receptor genes. This compound offers a useful new tool for examining the role of the Lck and FynT tyrosine kinases versus ZAP-70 in T cell activation as well as the role of other Src family kinases in receptor function.

The Src tyrosine kinase Hck is required for Tel-Abl- but not for Tel-Jak2-induced cell transformation

“…PP2 was initially described as a potent inhibitor of p56 Lck , p59 Fyn and p59/61 Hck while PP1 was reported to be selective for Fyn and Lck over other members of the Src kinases family (Hanke et al, 1996). Incubation with PP2 and, to a lesser extent, with PP1 resulted in a dosedependent inhibition of Tel-Abl-expressing cells growth while Ba/F3 cells expressing Tel-Jak2 remained unaffected ( Figure 2a).…”

Inhibition of pp60c-Src reduces Bcl-XL expression and reverses the transformed phenotype of cells overexpressing EGF and HER-2 receptors

“…In order to examine whether inhibiting Src activity is su cient for inducing the e ects observed by reduction of the Src protein we employed the selective Src inhibitor PP1 (Hanke et al, 1996). This inhibitor is a poor blocker of the EGF and IGF-1 receptors in cellfree systems as well as in cellular assays; PP1 does not inhibit signi®cantly the kinase activity of these receptors in intact cells up to 50 mM (Hanke et al, 1996 and our unpublished results).…”

“…To study this hypothesis further, we repressed c-Src expression with SRC antisense RNA. In addition, we also used a complementary approach in examining the role of Src in transformation by employing the selective Src family kinase inhibitor, PP1 (Hanke et al, 1996). PP1 potently inhibits kinase activity without a ecting Src protein levels, enabling us to examine the contribution of Src kinase activity to the transformed phenotype.…”

Activation of FAK and Src are receptor-proximal events required for netrin signaling

“…Hence, we tested the effect of Src using the SFK-specific inhibitor PP2 (ref. 21). PP2, but not its inactive analog PP3, inhibited netrin-stimulated tyrosine phosphorylation of DCC and FAK (Fig.…”