PP2

The Src family of non-receptor tyrosine kinases regulate cell adhesion, growth, and differentiation through activation of multiple intracellular signaling pathways. Normally inactive, Src kinases are transiently activated during mitosis and constitutively activated by abnormal mutations. PP2 is a potent, reversible, ATP-competitive, and selective inhibitor of the Src family of protein tyrosine kinases. It inhibits p56^lck (IC₅₀ = 4 nM), p59^fynT (IC₅₀ = 5 nM), Hck (IC₅₀ = 5 nM), and Src (IC₅₀ = 100 nM). PP2 does not significantly affect the activity of EGFR kinase (IC₅₀ = 480 nM), JAK2 (IC₅₀ > 50 μM), or ZAP-70 (IC₅₀ > 100 μM). PP2 inhibits the activation of focal adhesion kinase as well as its phosphorylation at Tyr⁵⁷⁷. PP2 also inhibits anti-CD3-stimulated tyrosine phosphorylation of human T-cells with an IC₅₀ value of 600 nM.

PP2 has been used:

• to analyze the effects of Src/focal adhesion kinase (FAK) signaling on IQ domain GTPase-activating protein 1 (IQGAP1)-mediated anoikis resistance
• for Src inhibition to study its effect on epidermal growth factor receptor (EGFR) and nuclear factor erythroid 2-related factor 2 (Nrf2) phosphorylation in non-small cell lung cancer (NSCLC) cells
• for pharmacological inhibition of SRC in MDA-MB-231 breast cancer cells

Selective inhibitor of Src-family tyrosine kinases. Inhibits p56 lck and p59 fynT (IC 50 values are 4 and 5 nM respectively). Displays > 10000-fold selectivity over ZAP-70 and JAK2. Moderately inhibits CSK (IC 50 = 0.73 μ M).

This cell-permeable and photosensitive ATP site-directed pyrazolepyrimidine (FW = 301.78 g/mol), also known as 4-amino-5-(4- chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine and tyrphostin AG 1879, potently inhibits Lck and Fyn protein kinases, with IC50 values of 4 nM and 5 nM. PP2 is ~100x less potent toward EGFR and is inactive for ZAP-70, JAK2 and PKA. PP2 prevented serum-independent growth of RET/PTC1-transformed NIH3T3 fibroblasts and of TPC1 and FB2, two human papillary thyroid carcinoma cell lines that carry spontaneous RET/PTC1 rearrangements. PP2 activates the E-cadherin-mediated cell adhesion system, suppressing metastasis in cancer cells. In cervical cancer cells (HeLa and SiHa), 10 μM PP2 down-regulates pSrc-Y416, pEGFR-Y845, and pEGFR-Y1173 expression levels, while downregulatING pSrc-Y416 and pEGFR-Y845, but not pEGFR-Y1173. PP2 is also a potential neuroprotective agent in cerebral ischemia-reperfusion. Target(s): casein kinase 1d, IC50 = 1.3 μM; Csk protein-tyrosine kinase; focal adhesion kinase; lymphocyte kinase, IC50 = 0.06 μM; p56lck, IC50 = 4 nM; p59fynT, IC50 = 5 nM; receptor proteintyrosine kinase; src protein-tyrosine kinase, IC50 = 0.7 μM (5,11,12- 23); stress-activated protein kinase 2a/p38, IC50 = 1.4 μM; and Yes kinase.