Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), such as gefitinib, erlotinib, and afatinib, have greatly improved treatment efficacy in non-small cell lung cancer (NSCLC) patients with drug-sensitive EGFR mutations. However, in some TKI responders, the benefits of such targeted therapies are limited by the rapid development of resistance, and strategies to overcome this resistance are urgently needed. Studies of drug resistance in cancer cells typically involve long term in vitro induction to obtain stably acquired drug-resistant cells followed by elucidation of resistance mechanisms, but the immediate responses of cancer cells upon drug treatment have been ignored. The aim of this study was to investigate the immediate responses of NSCLC cells upon treatment with EGFR TKIs.Both NSCLC cells, ie, PC9 and H1975, showed immediate enhanced adhesion-related responses as an apoptosis-countering mechanism upon first-time TKI treatment. By gene expression and pathway analysis, adhesion-related pathways were enriched in gefitinib-treated PC9 cells. Pathway inhibition by small-hairpin RNAs or small-molecule drugs revealed that within hours of EGFR TKI treatment, NSCLC cells used adhesion-related responses to combat the drugs. Importantly, we show here that the Src family inhibitor, dasatinib, dramatically inhibits cell adhesion-related response and greatly enhances the cell-killing effects of EGFR TKI (gefitinib for the PC9 cells; afatinib for the H1975 cells) in NSCLC cells, which would otherwise escape the TKI-induced apoptosis.Results from this study indicate that NSCLC cells can employ the adhesion response as a survival pathway to survive under EGFR-targeted therapy. Simultaneous targeting of EGFR signaling and adhesion pathways would further boost the efficacy of EGFR-targeted therapy in NSCLC.
Background. Enterovirus 71 (EV71) can cause severe diseases and even lead to death in children. There is no vaccine or specific antiviral therapy to prevent or cure EV71 infection. Although interferon (IFN)–α has been used in the treatment of several viral infections, we found that IFN-α alone was ineffective in restricting EV71 replication in Vero cells. Methods. Through a bioinformatics analysis, several cellular proteins in the IFN response pathway were identified as susceptible substrates that might be degraded by the EV71-encoded 3C protease (3Cpro). Results. Indeed, IRF9 was shown to be vulnerable to 3Cpro cleavage, as revealed by enzyme-based and cell-based assays. Thus, the IFN-mediated antiviral mechanism compromised by the viral 3Cpro in EV71-infected cells may be accountable, at least partially, for that IFN-α cannot inhibit EV71 replication. Because rupintrivir (AG7088) is known to be an effective EV71 inhibitor, we investigated the effects of the combination of rupintrivir and IFN-α on EV71 replication and found that they strongly synergized with each other in inhibiting EV71 replication. Conclusions. Because rupintrivir was shown to be generally tolerable in earlier clinical investigations, it is worth evaluating whether a combination of rupintrivir and IFN-α could be an effective treatment for EV71.
Peroxisome proliferator-activated receptor γ (PPARγ) is well-known as the receptor of thiazolidinedione antidiabetic drugs. In this paper, we present a successful example of employing structure-based virtual screening, a method that combines shape-based database search with a docking study and analogue search, to discover a novel family of PPARγ agonists based upon pyrazol-5-ylbenzenesulfonamide. Two analogues in the family show high affinity for, and specificity to, PPARγ and act as partial agonists. They also demonstrate glucose-lowering efficacy in vivo. A structural biology study reveals that they both adopt a distinct binding mode and have no H-bonding interactions with PPARγ. The absence of H-bonding interaction with the protein provides an explanation why both function as partial agonists since most full agonists form conserved H-bonds with the activation function helix (AF-2 helix) which, in turn, enhances the recruitment of coactivators. Moreover, the structural biology and computer docking studies reveal the specificity of the compounds for PPARγ could be due to the restricted access to the binding pocket of other PPAR subtypes, i.e., PPARα and PPARδ, and steric hindrance upon the ligand binding.
Proteases fulfill multiple roles in health and disease, and considerable interest has been expressed in the design and development of synthetic inhibitors of disease-related proteases. Virus-encoded proteases have been shown to be involved in the replication of many viruses. The success of anti-HIV-1 therapy using specific and potent protease inhibitors suggests that viral proteases can be the valid molecular targets for the development of antiviral drugs against other viruses. Intensive genetic and biochemical studies have been conducted on viral proteases and new insights and results are rapidly emerging. This work reviews features of viral proteases with respective to the development of effective antiviral therapy.
Overexpression or/and activating mutation of FLT3 kinase play a major driving role in the pathogenesis of acute myeloid leukemia (AML). Hence, pharmacologic inhibitors of FLT3 are of therapeutic potential for AML treatment. In this study, BPR1J-340 was identified as a novel potent FLT3 inhibitor by biochemical kinase activity (IC50 approximately 25 nM) and cellular proliferation (GC50 approximately 5 nM) assays. BPR1J-340 inhibited the phosphorylation of FLT3 and STAT5 and triggered apoptosis in FLT3-ITD+ AML cells. The pharmacokinetic parameters of BPR1J-340 in rats were determined. BPR1J-340 also demonstrated pronounced tumor growth inhibition and regression in FLT3-ITD+ AML murine xenograft models. The combination treatment of the HDAC inhibitor vorinostat (SAHA) with BPR1J-340 synergistically induced apoptosis via Mcl-1 down-regulation in MOLM-13 AML cells, indicating that the combination of selective FLT3 kinase inhibitors and HDAC inhibitors could exhibit clinical benefit in AML therapy. Our results suggest that BPR1J-340 may be further developed in the preclinical and clinical studies as therapeutics in AML treatments.
'/%3e%3cuse xlink:href='%23a' transform='rotate(60)'/%3e%3ccircle r='17' fill='%23000095'/%3e%3ccircle r='15' fill='%23fff'/%3e%3c/svg%3e)
