SB203580, also called 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl) 1Himidazole [6], is a specific pyridinyl imidazole inhibitor of p38-MAPK (Mitogen-activated Protein Kinase) signaling pathway [1] [3]. It was competitive with ATP with a selectivity probably determined by nonconserved regions within or near the ATP binding pocket and a Ki of 21 nM [3]. It inhibits c-Raf with an IC50 of 2 mM in vitro [4].
p38 MAPK signaling pathway enables cells to generate a plethora of different effects to interpret a wide range of external signals and respond appropriately. There is a core of three protein kinases acting sequentially in this pathway to ensure the diversity and specificity in cellular outcomes [5].
Exposure to 30 mM SB203580 significantly decreased the resistance of L1210/VCR cells to vincristine accompanied by the LC50 value of vincristine changed from 3.2036±0.521 to 0.5576±0.082 mM. Exposure to 10 mM SB203580 slightly changed the value of the resistance index, accompanied by the LC50 values of SB203580 to sensitive L1210 cells and to resistant cells were 39.26±2.2 mM and 52.06±7.6 mM, respectively [1].
In vivo, administration of SB203580 alone 24 h before the permanent middle cerebral arterial occlusion abolished the isoflurane preconditioning-induced neuroprotection. After isoflurane exposure, administration of SB203580 decreased phosphorylated p38 MAPK. SB203580 inhibited anisomycin pretreatment-induced neuroprotection [6].
References:
[1]. Miroslav Baranclk, Vierka Bohacova, Janka Kvackajova, et al. SB203580, a specific inhibitor of p38-MAPK pathway, is a new reversal agent of P-glycoprotein-mediated multidrug resistance. European Journal of Pharmaceutical Sciences, 2001, 14: 29-36.
[2]. Shuqiu Zheng and Zhiyi Zuo. Isoflurane Preconditioning Induces Neuroprotection against Ischemia via Activation of P38 Mitogen-Activated Protein Kinases. Molecular Pharmacology, 2004, 65:1172-1180.
[3]. Peter R. Young, Megan M. McLaughlin, Sanjay Kumar, et al. Pyridinyl Imidazole Inhibitors of p38 Mitogen-activated Protein Kinase Bind in the ATP Site. The Journal of Biological Chemistry, 1997, 272(18): 12116-12121.
[4]. Clare A Hall-Jackson, Michel Goedert, Philip Hedge, et al. E?ect of SB 203580 on the activity of c-Raf in vitro and in vivo. Oncogene, 1999, 18: 2047-2054.
[5]. Ana Cuadrado and Angel R. Nebreda. Mechanisms and functions of p38 MAPK signalling. Biochem. J., 2010, 429: 403-417.
[6]. Shuqiu Zheng and Zhiyi Zuo. Isoflurane Preconditioning Induces Neuroprotection against Ischemia via Activation of P38 Mitogen-Activated Protein Kinases. Mol Pharmacol, 2004, 65: 1172-1180.
