In conclusion we have demonstrated that diaryl pyrazolo pyri

In conclusion, we have demonstrated that ,-diaryl-1-pyrazolo[3,4-]pyrimidine-3,6-diamines represent a novel class of ACK1 inhibitors. The presence of a polar substituent at C-4 of the N-6 aryl ring was shown to be unnecessary for maintaining high levels of inhibitory activity. Furthermore, selectivity for ACK1 over some related kinases could be achieved via minimal structural modifications. Despite non-optimal pharmacokinetic profiles, these highly potent analogs represent a promising new lead series of ACK1 inhibitors which, with further study, may prove useful for identifying compounds suitable for in vivo experiments. Acknowledgments
Introduction Hepatitis C virus (HCV) infection is a major cause of liver disease. Nearly 200 million individuals worldwide are infected by HCV [1], [2], the majority of whom develop persistent infection that may lead to chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. It is well known that the efficacy of interferon (IFN)-based therapies depends on the HCV genotype and serum HCV-RNA level [3]. The current antiviral therapeutic regimen is pegylated IFNα used in combination with the nucleotide analog ribavirin. However, although ribavirin improves the effect of IFN, the eradication rate of HCV is only about 50% in patients infected with genotype 1b and approximately 80% in patients infected with other genotypes [4], [5], [6]. Several host factors that influence the efficacy of IFN therapies have been identified recently, including age, sex, liver fibrosis, and obesity [7], [8]. Recent studies, including our own, also demonstrated that the response to IFN therapy is associated with several single nucleotide polymorphisms (SNPs) in ifenprodil including: myxovirus resistance protein A (MxA), mannose-binding lectin (MBL), low-molecular-mass polypeptide 7 (LMP7), osteopontin (OPN), IFNα receptor 1 (IFNAR1), mitogen-activated protein kinase-activated protein kinase 3 (MAPKAPK3), and interleukin 28B (IL28B) [9], [10], [11], [12], [13], [14], [15]. During the initial steps of infection, HCV virus is taken up by hepatocytes in the liver in a multistep process involving a number of factors [16]. A better understanding of the mechanisms of HCV entry into the host cells could have important implications for developing strategies to prevent infection and therapies to treat chronic HCV disease. Initial host cell attachment seems to involve glycosaminoglycans, low-density lipoprotein receptor, scavenger receptor class B type I, CD81, and claudin-1 [17], [18], [19], [20], [21]. It was demonstrated recently that CD81 increases the levels of three Rho-family GTPase proteins; Rac1, Rho, and Cdc42 [22]. Rho GTPases are molecular switches that cycle between an inactive GDP-bound state and an active GTP-bound state. Inhibition of Rac1 and Cdc42 with specific small interfering RNAs (siRNAs) or inhibitors significantly reduced the infectivity of HCV, with Cdc42 knockdown producing the most dynamic reduction in infectivity. These findings implicated Cdc42 as a key molecule directing HCV entry and suggesting that polymorphisms in the CDC42 gene that modulate protein expression or function might affect the response to HCV therapies. In addition, non-receptor protein tyrosine kinase (PTK) proteins such as Janus kinase, which are essential for IFN activity, transmit signals into the host cells. ACK1 is one such PTK that also binds selectively to Cdc42 in humans [23], [24], [25]. ACK1 can phosphorylate several proteins and mediate EGF signaling to Rho-family GTPases including Cdc42 [26]. However, whether ACK1 gene expression affects the outcome of IFN therapy for HCV infection remains unknown. The present study examined whether CDC42 and ACK1 SNPs are associated with the different response levels to IFN therapy using a tagging-SNP approach. The results provide genetic and functional evidence for the role of the ACK1 gene activity in the responsiveness to IFN therapy.