Kinase experiment:

To determine the reversibility of the inhibition of protein tyrosine phosphatases (PTP) activity by BVT948 (BVT.948), 50 ng of PTP1B is incubated in 100 μL of assay buffer with 20 μM BVT948 for 10 min in a concentration device. The sample is then centrifuged at 14,000 rpm at 4℃ for 12 min. The concentrate is subsequently washed three times with 100 μL of assay buffer followed by centrifugation. After washing, 190 μL of assay buffer is added to the sample, increasing the volume to 200 μL. Twenty microliters are used in assays measuring enzyme activity remaining using para-nitrophenyl phosphate (pNPP) as a substrate. Controls includes enzyme, which is treated with inhibitor but not washed, and enzyme, which is not treated with BVT948 but is put through the incubation and washing procedures[1].

Cell experiment:

L6 myocytes are maintained in minimum essential medium-alpha (α-MEM) supplemented with 10% fetal bovine serum and 100 IU/mL penicillin-streptomycin at 37℃ in 5% CO2. Cells are seeded into 24-well plates, and the medium is replaced with α-MEM containing 2% fetal calf serum to induce differentiation into myotubes. The medium is changed every other day, and cytidine (0.24 mg/mL medium) is added to the cultures at days 7 to 9 to suspend cycling cells. The cells are used in experiments after overnight serum starvation at days 11 to 16. They are treated with or without 25 μM BVT948 (BVT.948) for 30 min followed by 5 min of insulin (25 nM) stimulation. After freezing with liquid N2, the cells are lysed with a Tris-HCl buffer, pH 7.4, containing 1% Nonidet-40, 0.25% sodium deoxycholate, 150 mM NaCl, 1 mM EDTA, 1 mM EGTA, 1 mM sodium orthovanadate, 10 mM β-glycerophosphate, 5 mM sodium pyrophosphate, and complete protease inhibitor cocktail The cell extracts are centrifuged at 14,000 g for 10 min, and the supernatants are used in the Delfia assay[1].

Animal experiment:

Male mice 12 to 14 weeks old are used in this study. They are divided into equal groups (n=9) based on blood glucose levels. At time 0, the mice are injected with vehicle (NaCl with 10% DMSO) or BVT948 (BVT.948) (0.3 and 3 μmol/kg) and 1 U/kg insulin intraperitoneally. Blood glucose is determined from tail vein sampling at 0, 30, 60, and 120 min using a glucometer[1].

BVT948 is a noncompetitive, cell-permeable and novel PTP inhibitor with an IC50 of 0.09-1.7 μM. [1]

Protein-tyrosine phosphatases (PTPs) are involved in the regulation of diverse intracellular signalings. It can promote cell migration in mammalian cells [2], induce MMP-9 expression in MCF-7 breast cancer cells. [3]

BVT948 blocks breast cancer cell invasion via suppression of the expression of MMP-9. Treatment of 0.5, 1 or 5 μM BVT948 for 24 h did not cause any significant changes in MCF-7 cell viability. BVT948 inhibited TPA-induced MMP-9 up-regulation in a dose-dependent manner. Treatment MCF-7 cells with BVT948 blocked the up-regulation of TPA-induced MMP-9 protein expression. BVT948 significantly diminished TPA-induced MMP-9 secretion. BVT948 diminished 50% cell invasion after the TPA-induced. BVT948 inhibits NF-κB activation by suppressing IκBα degradation and the nuclear translocation of NF-κB in TPA-treated MCF-7 cells. The MAPK pathways are not involved in the inhibition of TPA-induced MMP-9 expression by BVT948. [4]

References:
1. Liljebris, C., Baranczewski, P., Bjorkstrand, E., et al. Oxidation of protein tyrosine phosphatases as a pharmaceutical mechanism of action: A study using 4-hydroxy-3,3-dimethyl-2H-benzo [g]indole-2,5(3H)-dione. J Pharmacol Exp Ther 309(2) 711-719 (2004).
2. Jallal, B., Mossie, K., Vasiloudis, G., Knyazev, P., Zachwieja, J., Clairvoyant, F., Schilling, J. and Ullrich, A. (1997) The receptor-like protein-tyrosine phosphatase DEP-1 is constitutively associated with a 64-kDa protein serine/threonine kinase. J. Biol. Chem. 272, 12158-12163.
3. Wang, F. M., Liu, H. Q., Liu, S. R., Tang, S. P., Yang, L. and Feng, G. S. (2005) SHP-2 promoting migration and metastasis of MCF-7 with loss of E-cadherin, dephosphorylation of FAK and secretion of MMP-9 induced by IL-1 beta in vivo and in vitro. Breast Cancer Res. Treat. 89, 5-14.
4. Hwang BM, Chae HS, Jeong YJ et al.Protein tyrosine phosphatase controls breast cancer invasion through the expression of matrix metalloproteinase-9.BMB Rep. 2013 Nov;46(11):533-8.