Lck Inhibitor

Lck Inhibitor is a small-molecule inhibitor of with IC50 value of 7 nM [1].
The lymphocyte specific kinase which expressed in NK cells and T-cells is a member of the Src kinase family. It takes participate in the T-cell receptor (TCR) signal transduction and affects the expression of genes associated with cell proliferation, cytokine release and T-cell survival. Therefore small-molecule inhibitors of Lck with potent activities and bioavailable efficacies have been designed and developed as therapeutic agents for the treatment for T-cell-mediated autoimmune and organ transplant rejection [1].
Lck Inhibitor showed high selectivity against Lck over another Src family kinase Src and the kinases related to inflammation and angiogenesis such as p38 and VEGFR-2 with IC50 values of 0.12, > 10 and 5.1 μM, respectively. Lck Inhibitor also showed more than 1000-fold greater selectivity over CDK, MAPK and the RSK family. In cultured human mixed lymphocytes, the inhibitor significantly suppressed the activation of T-cells with IC50 value of 47 nM. Besides that, this compound inhibited IL-2 secretion induced by T-cell receptor with IC50 value of 0.46 μM. The good potency and selectivity of the Lck Inhibitor were due to the critical aniline side chain within a N-methylpiperazine moiety. It extended to the ATP-binding pocket of the enzyme and formed hydrogen bond interactions with the linker region [1].
In rats model with arthritis induced by the injection of porcine type II collagen, oral administration of the compound dose-dependently suppressed the inflammation with ED50 value of 3.2 mg/kg. While in the adjuvant-induced arthritis model, oral administration of Lck Inhibitor also displayed significant anti- arthritis effects with ED50 value of 24 mg/kg [1].
References:
[1] Martin M W, Newcomb J, Nunes J J, et al. Structure-Based Design of Novel 2-Amino-6-phenyl-pyrimido [5', 4': 5, 6] pyrimido [1, 2-a] benzimidazol-5 (6 H)-ones as Potent and Orally Active Inhibitors of Lymphocyte Specific Kinase (Lck): Synthesis, SAR, and In Vivo Anti-Inflammatory Activity. Journal of medicinal chemistry, 2008, 51(6): 1637-1648.   

P56(lck) kinase inhibitor studies: a 3D QSAR approach towards designing new drugs from flavonoid derivatives.[Pubmed:24878734]

Int J Comput Biol Drug Des. 2014;7(2-3):278-94.

Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) based on 3D-QSAR (3D-quantitative structure activity relationship) studies were carried out on 97 flavonoid derivatives as potent P56(lck) protein tyrosine kinase inhibitors. The best prediction was obtained with CoMFA standard model (q(2) = 0.838, r(2) = 0.948) using steric, electrostatic along with CoMSIA standard model (q(2) = 0.714, r(2) = 0.921) using steric, electrostatic, hydrophobic, hydrogen bond donor and acceptor fields. Of the 97 molecules a training set of 76 compounds and the predictive ability of the QSAR model were assessed employing a test set of 21 compounds. The resulting CoMFA and CoMSIA contour maps were used to identify the structural features relevant to the biological activity in this series of flavonoid derivatives, based upon which we identified and designed 10 novel molecules that showed superior inhibitory activity against P56(lck) protein which shed new light on effective therapeutic agents against these classes of enzymes.

Inhibition of Lck: evidence for a novel natural Src family kinase inhibitor.[Pubmed:21827365]

J Enzyme Inhib Med Chem. 2012 Aug;27(4):546-52.

Src family kinase (SFK) is a family of protein tyrosine kinases that play important roles in the development of various cancers. Here, we showed that a naturally occurring inhibitory factor of SFK can be extracted from the rat brain. This inhibitor strongly suppressed the activity of SFKs including Lck and Fyn. It did not inhibit other protein tyrosine kinases including Wee1 or serine/threonine kinases Mst2, Cdk5/p25, Cdk5/p35, and Cdk2/cyclin A. The inhibitor was not an ATPase, a phosphatase that dephosphorylates substrates of the SFK reaction, or a protease that degrades SFKs. Activity of mutant Lck with C-terminal tyrosine substituted with phenylalanine was also suppressed by the inhibitor to a similar extent of wild-type Lck, indicating that the inhibitor was not CSK. Gel filtration chromatography indicated that the molecular size of the prevalent form of this inhibitor was approximately 44 kDa.

Expression of human tyrosine kinase, Lck, in yeast Saccharomyces cerevisiae: growth suppression and strategy for inhibitor screening.[Pubmed:17100647]

Protein Pept Lett. 2006;13(9):915-20.

We report the successful expression and detection of a phosphorylated form of human T cell tyrosine kinase, Lck, in Saccharomyes cerevisiae, which leads to growth suppression of the yeast cells. Expression of an inactive Lck mutant resulted in no phosphorylation and no growth suppression, indicating that cell growth inhibition by Lck is due to the activity of the kinase, consistent with the observed tyrosine-phosphorylation of the Lck and yeast host cell proteins. The addition of a known inhibitor of Lck to the cell culture resulted in recovery of cell growth expressing the active Lck, suggesting that the growth inhibition by lck gene expression can be used to screen inhibitors for the gene product. We have extended such approach to Tob, another potential therapeutic target.

Discovery of A-770041, a src-family selective orally active lck inhibitor that prevents organ allograft rejection.[Pubmed:16216497]

Bioorg Med Chem Lett. 2006 Jan 1;16(1):118-22.

We describe the identification, SAR, and pharmacology of the src-family selective Lck Inhibitor A-770041 that prolongs the survival of major histocompatibility mismatched allografts in models of solid organ transplant rejection for greater than 65 days.

Structure-based design of novel 2-amino-6-phenyl-pyrimido[5',4':5,6]pyrimido[1,2-a]benzimidazol-5(6H)-ones as potent and orally active inhibitors of lymphocyte specific kinase (Lck): synthesis, SAR, and in vivo anti-inflammatory activity.[Pubmed:18278858]

J Med Chem. 2008 Mar 27;51(6):1637-48.

Lck, or lymphocyte specific kinase, is a cytoplasmic tyrosine kinase of the Src family expressed in T-cells and NK cells. Genetic evidence from knockout mice and human mutations demonstrates that Lck kinase activity is critical for T-cell receptor-mediated signaling, leading to normal T-cell development and activation. A small molecule inhibitor of Lck is expected to be useful in the treatment of T-cell-mediated autoimmune and inflammatory disorders and/or organ transplant rejection. In this paper, we describe the structure-guided design, synthesis, structure-activity relationships, and pharmacological characterization of 2-amino-6-phenylpyrimido[5',4':5,6]pyrimido[1,2- a]benzimidazol-5(6 H)-ones, a new class of compounds that are potent inhibitors of Lck. The most promising compound of this series, 6-(2,6-dimethylphenyl)-2-((4-(4-methyl-1-piperazinyl)phenyl)amino)pyrimido[5',4': 5,6]pyrimido-[1,2- a]benzimidazol-5(6 H)-one ( 25), exhibits potent inhibition of Lck kinase activity. This activity translates into inhibition of in vitro cell-based assays and in vivo models of T-cell activation and arthritis, respectively.