Clinicopathologic features and molecular analysis of enterovirus 71 infection: report of an autopsy case from the epidemic of hand, foot and mouth disease in China.

A 15-month boy with fatal hand, foot, and mouth disease (HFMD) exhibited atypical symptoms and progressed rapidly to death. An autopsy was performed the next day and tissue sections were stained for histopathological examination. His intestinal samples were tested for enterovirus 71 (EV71), and the whole-genome sequence of EV71 was analyzed. An autopsy revealed that the central nervous system, lungs, and gut displayed severe meningitis and brainstem encephalitis, remarkable pulmonary congestion, edema, moderate inflammatory infiltration, and hemorrhage as well as intestinal mucosal congestion, epithelial necrosis, thinning intestinal wall, and submucosal lymphoid follicular hyperplasia. The heart showed myocardial interstitial congestion, myocardial edema, and some inflammatory infiltrates. There were no significant alterations in the architecture of other organs. EV71 antigen and apoptotic cells were detected in brain, lung and intestine by immunohistochemical staining and TUNEL (TdT-mediated dUTP nick-end labeling) respectively. Intestinal contents and intestinal autopsy samples of this case were positive for EV71, and the EV71 strain was classified as subgenogroup C4. In China, the severe forms of HFMD were mostly caused by EV71 subgenogroup C4 infection. Severe intestinal damages may relate to EV71 subgenogroup C4 infection. Thus, children with severe EV71 HFMD may have serious pathological changes in their central nervous system, lungs, and gut. Physicians should pay special attention to infants with atypical symptoms, particularly in EV71 epidemic areas for early diagnosis and treatment.

Investigation of novel 7,8-disubstituted-5,10-dihydro-dibenzo[b,e][1,4]diazepin-11-ones as potent Chk1 inhibitors.

The synthesis and structure-activity relationships (SAR) of Chk1 inhibitors based on a 5,10-dihydro-dibenzo[b,e][1,4]diazepin-11-one core are described. Specifically, an exploration of the 7 and 8 positions on this previously disclosed core afforded compounds with improved enzymatic and cellular potency.

Design, synthesis, and biological activity of 5,10-dihydro-dibenzo[b,e][1,4]diazepin-11-one-based potent and selective Chk-1 inhibitors.

A novel series of 5,10-dihydro-dibenzo[b,e][1,4]diazepin-11-ones have been synthesized as potent and selective checkpoint kinase 1 (Chk1) inhibitors via structure-based design. Aided by protein X-ray crystallography, medicinal chemistry efforts led to the identification of compound 46d, with potent enzymatic activity against Chk1 kinase. While maintaining a low cytotoxicity of its own, compound 46d exhibited a strong ability to abrogate G2 arrest and increased the cytotoxicity of camptothecin by 19-fold against SW620 cells. Pharmacokinetic studies revealed that it had a moderate bioavailabilty of 20% in mice. Two important binding interactions between compound 46b and Chk1 kinase, revealed by X-ray cocrystal structure, were hydrogen bonds between the hinge region and the amide bond of the core structure and a hydrogen bond between the methoxy group and Lys38 of the protein.

Design, synthesis, and biological activity of 4-[(4-cyano-2-arylbenzyloxy)-(3-methyl-3H-imidazol-4-yl)methyl]benzonitriles as potent and selective farnesyltransferase inhibitors.

A novel series of 4-[(4-cyano-2-arylbenzyloxy)-(3-methyl-3H-imidazol-4-yl)methyl]benzonitriles have been synthesized as selective farnesyltransferase inhibitors using structure-based design. X-ray cocrystal structures of compound 20-FTase-HFP and A313326-FTase-HFP confirmed our initial design. The decreased interaction between the aryl groups and Ser 48 in GGTase-I binding site could be one possible reason to explain the improved selectivity for this new series of FTase inhibitors. Medicinal chemistry efforts led to the discovery of compound 64 with potent cellular activity (EC(50) = 3.5 nM) and outstanding pharmacokinetic profiles in dog (96% bioavailable, 18.4 h oral t(1/2), and 0.19 L/(h x kg) plasma clearance).

[Epidemiological and etiological characteristics of hand-foot-mouth disease in Ningbo, Zhejiang province, 2008-2011].

OBJECTIVE: To analyze the epidemiological characteristics of hand foot and mouth disease (HFMD) in Ningbo. METHODS: A descriptive analysis was conducted through the surveillance data of HFMD in Ningbo, Zhejiang province, from 2008 to 2011. Genes on EV71 and Cox A16 were amplified with RT-PCT from the stool samples of HFMD patients. Sequences were analyzed by bioinformatics software. RESULTS: 37 524 cases of HFMD were reported from 2008 to 2011, including 196 severe cases and 12 deaths. The reported incidence was 145.26 per 100 000 and the case fatality was 0.03%. Cases in children aged 5 or younger accounted for 95.89%, and the scattered cases accounted for 64.10%. Xiangshan and Ninghai counties had the highest incidence rates in Ningbo. The peak of incidence was from April to July. The number of male patients was obviously higher than females. 2394 cases of HFMD were laboratory confirmed and EV71 with the predominant epidemic strain. Data from phylogenetic analysis revealed that EV71 isolated from HFMD patients in Ningbo belonged to C4a evolution branch of C4 sub-genotype, with several transmission chains. Cox A16 belonged to B1 evolution branch. 53.48% of the healthy children in Ningbo showed EV71 antibody positive. The geometric mean of the antibody titer (GMT) was 11.23 (8.33 - 14.98) in healthy children. Cox A16 antibody was detected at 63.18% of the healthy children in Ningbo. GMT in healthy children was 12.61 (6.70 - 16.52). CONCLUSION: HFMD was highly endemic in Ningbo, with children under 5 years old were at high-risk. The major etiologic agent was EV71 which belonged to C4a in the C4 sub-genotypes. Cox A16 belonged to the B1 evolution branch, which were in line with the predominant virus circulating in the mainland of China.

Cyclin B1 is an efficacy-predicting biomarker for Chk1 inhibitors.

Chk1 is the major mediator of cell-cycle checkpoints in response to various forms of genotoxic stress. Although it was previously speculated that checkpoint abrogation due to Chk1 inhibition may potentiate the efficacy of DNA-damaging agents through induction of mitotic catastrophe, there has not been direct evidence proving this process. Here, through both molecular marker and morphological analysis, we directly demonstrate that specific downregulation of Chk1 expression by Chk1 siRNA potentiates the cytotoxicities of topoisomerase inhibitors through the induction of premature chromosomal condensation and mitotic catastrophe. More importantly, we discovered that the cellular cyclin B1 level is the major determinant of the potentiation. We show that downregulation of cyclin B1 leads to impairment of the induction of mitotic catastrophe and correspondingly a reduction of the potentiation ability of either Chk1 siRNA or a small molecule Chk1 inhibitor. More significantly, we have extended the study by examining a panel of 10 cancer cell-lines with different tissue origins for their endogenous levels of cyclin B1 and the ability of a Chk1 inhibitor to sensitize the cells to DNA-damaging agents. The cellular levels of cyclin B1 positively correlate with the degrees of potentiation achieved. Of additional interest, we observed that the various colon cancer cell lines in general appear to express higher levels of cyclin B1 and also display higher sensitivity to Chk1 inhibitors, implying that Chk1 inhibitor may be more efficacious in treating colon cancers. In summary, we propose that cyclin B1 is a biomarker predictive of the efficacy of Chk1 inhibitors across different types of cancers. Unlike previously established efficacy-predictive biomarkers that are usually the direct targets of the therapeutic agents, cyclin B1 represents a non-drug-target biomarker that is based on the mechanism of action of the target inhibitor. This finding may be potentially very useful for the stratification of patients for Chk1 inhibitor clinical trials and hence, maximize its chance of success.

Discovery of 1,4-dihydroindeno[1,2-c]pyrazoles as a novel class of potent and selective checkpoint kinase 1 inhibitors.

A new class of checkpoint kinase 1 (CHK-1) inhibitors bearing a 1,4-dihydroindeno[1,2-c]pyrazole core was developed after initial hits from high throughput screening. The efficient hit-to-lead process was facilitated by X-ray crystallography and led to potent inhibitors (<10nM) against CHK-1. X-ray co-crystal structures of bound inhibitors demonstrated that two sub-series of this class of compounds, exemplified by 21 and 41, exhibit distinctive hydrogen bonding patterns in the specificity pocket of the active site. Two compounds, 41 and 43, were capable of potentiating doxorubicin and camptothecin, both DNA-damaging agents, in cell proliferation assays (MTS and soft agar assays) and abrogating G2/M checkpoint in a mechanism-based FACS assay.

Selective Chk1 inhibitors differentially sensitize p53-deficient cancer cells to cancer therapeutics.

The majority of cancer therapeutics induces DNA damage to kill cells. Normal proliferating cells undergo cell cycle arrest in response to DNA damage, thus allowing DNA repair to protect the genome. DNA damage induced cell cycle arrest depends on an evolutionarily conserved signal transduction network in which the Chk1 kinase plays a critical role. In mammalian cells, the p53 and RB pathways further augment the cell cycle arrest response to prevent catastrophic cell death. Given the fact that most tumor cells suffer defects in the p53 and RB pathways, it is likely that tumor cells would depend more on the Chk1 kinase to maintain cell cycle arrest than would normal cells. Therefore Chk1 inhibition could be used to specifically sensitize tumor cells to DNA-damaging agents. We have previously shown that siRNA-mediated Chk1 knockdown abrogates DNA damage-induced checkpoints and potentiates the cytotoxicity of several DNA-damaging agents in p53-deficient cell lines. In this study, we have developed 2 potent and selective Chk1 inhibitors, A-690002 and A-641397, and shown that these compounds abrogate cell cycle checkpoints and potentiate the cytotoxicity of topoisomerase inhibitors and gamma-radiation in p53-deficient but not in p53-proficient cells of different tissue origins. These results indicate that it is feasible to achieve a therapeutic window with 1 or more Chk1 inhibitors in potentiation of cancer therapy based on the status of the p53 pathway in a wide spectrum of tumor types.

Design, synthesis, and activity of achiral analogs of 2-quinolones and indoles as non-thiol farnesyltransferase inhibitors.

Beginning with the structure of tipifarnib (1), a series of inhibitors of FTase have been synthesized by transposition of the D-ring to the imidazole and subsequent modification of the 2-quinolone motif. The compounds in the new series may be achiral and have structural features that allow for analogs that are difficult or impossible to make in the tertiary carbon-based tipifarnib series. The most potent compound (4d) is 4 times more active in vitro against FTase than tipifarnib.

Benzimidazolones and indoles as non-thiol farnesyltransferase inhibitors based on tipifarnib scaffold: synthesis and activity.

A series of analogs of tipifarnib (1) has been synthesized as inhibitors of FTase by substituting the benzimidazolones and indoles for the 2-quinolone of tipifarnib. The novel benzimidazolones are potent and selective FTase inhibitors (FTIs) with IC(50) values of the best compounds close to that of tipifarnib. The current series demonstrate good cellular activity as measured in their inhibiting the Ras processing in NIH-3T3 cells, with compounds 2c and 2f displaying EC(50) values of 18 and 22nM, respectively.

Design and synthesis of o-trifluoromethylbiphenyl substituted 2-amino-nicotinonitriles as inhibitors of farnesyltransferase.

A non-methionine FT inhibitor lead structure (1) was designed through computer modeling of the peptidomimetic FT inhibitor ABT839. Optimization of this lead resulted in compounds 2e and 2g, with FT IC(50) values of 1.3 and 1.8 nM, GGT IC(50) of 1400 nM, and EC(50) (Ras processing) values of 13 and 11 nM, respectively.

A highly potent and selective farnesyltransferase inhibitor ABT-100 in preclinical studies.

Ras mutation has been detected in approximately 20-30% of all human carcinomas, primarily in pancreatic, colorectal, lung and bladder carcinomas. The indirect inhibition of Ras activity by inhibiting farnesyltransferase (FTase) function is one therapeutic intervention to control tumor growth. Here we report the preclinical anti-tumor activity of our most advanced FTase inhibitor (FTI), ABT-100, and a direct comparison with the current clinical candidates. ABT-100 is a highly selective, potent and orally bioavailable FTI. It broadly inhibits the growth of solid tumors in preclinical animal models. Thus, ABT-100 is an attractive candidate for further clinical evaluation. In addition, our results provide plausible insights to explain the impressive potency and selectivity of ABT-100. Finally, we have demonstrated that ABT-100 significantly suppresses the expression of vascular endothelial growth factor (VEGF) mRNA and secretion of VEGF protein, as well as inhibiting angiogenesis in the animal model.

Synthesis and biological evaluation of 4-[3-biphenyl-2-yl-1-hydroxy-1-(3-methyl-3H-imidazol-4-yl)-prop-2-ynyl]-1-yl-benzonitrile as novel farnesyltransferase inhibitor.

Farnesyltransferase inhibitors (FTIs) have emerged as a novel class of anti-cancer agents. Analogues of the potent FTI, 4-[3-biphenyl-1-hydroxy-1-(3-methyl-3H-imidazol-4-yl)-prop-2-ynyl]-1-yl-benzonitrile, were synthesized and tested in vitro for their inhibitory activities. The synthesis and detailed biological data of this series of analogues are presented.

Synthesis and biological evaluation of 4-[(3-methyl-3H-imidazol-4-yl)-(2-phenylethynyl-benzyloxy)-methyl]-benzonitrile as novel farnesyltransferase inhibitor.

Farnesyltransferase inhibitors (FTIs) have emerged as a novel class of anticancer agents. Analogues of the potent FTI, 4-[3-biphenyl-1-hydroxy-1-(3-methyl-3H-imidazol-4-yl)-prop-2-ynyl]-1-yl-benzonitrile, were synthesized and tested in vitro for their inhibitory activities. The most promising compound identified from this series is analogue 11 that possesses potent enzymatic and cellular activities.

Novel and selective imidazole-containing biphenyl inhibitors of protein farnesyltransferase.

A series of imidazole-containing biphenyls was prepared and evaluated in vitro for inhibition of FTase and cellular Ras processing. Several of these analogues, such as 21, are potent inhibitors of FTase (<1nM), FTase/GGTase selective (>300-fold) and cellularly active (

Synthesis and biological evaluation of 1-benzyl-5-(3-biphenyl-2-yl-propyl)-1H-imidazole as novel farnesyltransferase inhibitor.

Farnesyltransferase inhibitors (FTIs) have emerged as a novel class of anti-cancer agents. Analogs of the potent FTI, 1-benzyl-5-(3-biphenyl-2-yl-propyl)-1H-imidazole, were synthesized and tested in vitro for their inhibitory activities. The most promising compound identified from this series is analog 29 that possesses potent enzymatic and cellular activities.

Discovery of potent imidazole and cyanophenyl containing farnesyltransferase inhibitors with improved oral bioavailability.

A pyridyl moiety was introduced into a previously developed series of farnesyltransferase inhibitors containing imidazole and cyanophenyl (such as 4), resulting in potent inhibitors with improved pharmacokinetics.

Synthesis of 1H-pyridin-2-one derivatives as potent and selective farnesyltransferase inhibitors.

Two novel series of potent and selective FTase inhibitors have been synthesized using structure-based design. Medicinal chemistry efforts led to the discovery of compound 4e with potent cellular activity and good oral bioavailability in dog. A synthetic route toward novel heterocycles 1,5-dimethyl-6-oxo-4-aryl-1,6-dihydro-pyridine-2-carbonitrile was established. The structure of compound 5c was confirmed by X-ray crystallography.

Pyridone-containing farnesyltransferase inhibitors: synthesis and biological evaluation.

Farnesyltransferase inhibitors (FTIs) have been developed as potential anti-cancer agents due to their efficacy in blocking malignant growth in a variety of murine models of human tumors. To that end, we have developed a series of pyridone farnesyltransferase inhibitors with potent in vitro and cellular activity. The synthesis, SAR and biological properties of these compounds will be discussed.

Aryl tetrahydropyridine inhibitors of farnesyltransferase: glycine, phenylalanine and histidine derivatives.

Inhibitors of farnesyltransferase are effective against a variety of tumors in mouse models of cancer. Clinical trials to evaluate these agents in humans are ongoing. In our effort to develop new farnesyltransferase inhibitors, we have discovered a series of aryl tetrahydropyridines that incorporate substituted glycine, phenylalanine and histidine residues. The design, synthesis, SAR and biological properties of these compounds will be discussed.