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Supplementary Table 1 from A Small-Molecule Inhibitor of Bcl-XL Potentiates the Activity of Cytotoxic Drugs In vitro and In vivo

Inhibition of the prosurvival members of the Bcl-2 family of proteins represents an attractive strategy for the treatment of cancer. We have previously reported the activity of ABT-737, a potent inhibitor of Bcl-2, Bcl-XL, and Bcl-w, which exhibits monotherapy efficacy in xenograft models of small-cell lung cancer and lymphoma and potentiates the activity of numerous cytotoxic agents. Here we describe the biological activity of A-385358, a small molecule with relative selectivity for binding to Bcl-XL versus Bcl-2 (Ki's of 0.80 and 67 nmol/L for Bcl-XL and Bcl-2, respectively). This compound efficiently enters cells and co-localizes with the mitochondrial membrane. Although A-385358 shows relatively modest single-agent cytotoxic activity against most tumor cell lines, it has an EC50 of L for survival. In addition, A-385358 enhances the in vitro cytotoxic activity of numerous chemotherapeutic agents (paclitaxel, etoposide, cisplatin, and doxorubicin) in several tumor cell lines. In A549 non–small-cell lung cancer cells, A-385358 potentiates the activity of paclitaxel by as much as 25-fold. Importantly, A-385358 also potentiated the activity of paclitaxel in vivo. Significant inhibition of tumor growth was observed when A-385358 was added to maximally tolerated or half maximally tolerated doses of paclitaxel in the A549 xenograft model. In tumors, the combination therapy also resulted in a significant increase in mitotic arrest followed by apoptosis relative to paclitaxel monotherapy. (Cancer Res 2006; 66(17): 8731-9)

BACKGROUND Acetylcholinesterase inhibitors (AChEIs) and memantine are commonly prescribed medications for Alzheimer's disease (AD). Their concurrent use in AD randomized clinical trials (RCTs) is generally allowed but their effect in outcome measures is unsettled. OBJECTIVE To evaluate whether use of AChEIs and/or memantine across AD RCTs are associated with different rates of cognitive/functional decline. METHODS We pooled data from 5 RCTs of mild to moderate AD conducted by the Alzheimer's Disease Cooperative Study (ADCS) between 2002-2013. 1,423 participants with MMSE of 14-26 and completion of 12-18 months follow-up visits were analyzed. Trials did not randomize with respect to AChEIs or memantine. We defined 4 groups: AChEI (27%), memantine (16%), AChEIs+memantine (46%), and non-users (11%). Outcome measures were change in ADAS-cog-11, ADCS-ADL, and MMSE from baseline to 18 months. Fisher's exact test, Wilcoxon signed rank, and Spearman's tests were used to identify confounding variables. Mixed model repeated measures were used for adjustments and pairwise tests for comparing change in scores. RESULTS Age, apolipoprotein E, and initial MMSE were identified as covariates. Memantine and/or AChEIs users had greater impairment at entry than non-users. There was a significant decline on the ADAS-cog-11 in the memantine (estimate -4.2 p

Injected depot formulations of somatostatin peptide analogs are routinely used to treat acromegaly and neuroendocrine tumors (NETs). CRN00808 is a small molecule nonpeptide selective somatostatin receptor 2 agonist whose safety, pharmacokinetics (PK), and pharmacodynamics (PD) has been characterized in preclinical studies. This study describes the final results from a first-in-human, single and multiple ascending dose Phase 1 study in healthy volunteers to measure the safety, PK, PD, and midazolam drug interaction potential of CRN00808 (NCT03276858; preliminary results with blinded safety data presented at ENDO 2018). In the single dose arm of the study, cohorts of 8 subjects (6 active: 2 placebo) received CRN00808 as an oral solution or capsules (1.25 mg to 60 mg, or placebo). The effect of food on CRN00808 PK was also evaluated. In the multiple dose arm, cohorts of 9 subjects (6 active: 3 placebo) received CRN00808 capsules once daily (5 mg to 30 mg, or placebo) for 7-10 days. In the drug-interaction arm, a single cohort of 8 subjects received 20 mg of CRN00808 for 7 days; midazolam PK was assessed before (Day -2) and after (Day 7) administration of CRN00808. Safety and PK were assessed in all phases of the study. Suppression of GHRH-induced GH secretion and suppression of serum IGF-1 were measured as PD endpoints in the single and multiple dose phases of the study, respectively. Once daily administration of 5-30 mg CRN00808 capsules exhibited dose-dependent increases in peak (Cmax) and total (AUC) plasma exposures. The apparent terminal elimination half-life was determined to be of 42-50 hours and steady state was achieved in 3-5 days. Capsules taken with a standard high fat, high calorie meal resulted in a markedly lower plasma CRN00808 AUC (83%). Oral administration of CRN00808 resulted in dose-dependent suppression of both GHRH stimulated GH and IGF-1 secretion; a single 10 mg dose was found to cause 91% suppression of GHRH-stimulated GH and 10 mg once per day for 10 days resulted in maximal suppression of serum IGF-1. Midazolam PK was unaffected by co-administration of 20 mg CRN00808, suggesting little or no risk of drug interaction with CYP3A4/5 substrates. Treatment emergent adverse events associated with CRN00808 were generally mild and transient, and consistent with those reported with other somatostatin agonists. In conclusion, results from this Phase I clinical trial in healthy volunteers support further clinical development of CRN00808 as a once-daily oral treatment of patients with acromegaly.

Background and objective ST101, an acetylcholine release agent with efficacy in rodent memory and cognition models, was assessed for clinical safety and efficacy. Methods A phase 2 double blind, placebo-controlled study enrolled 210 AD patients (MMSE 10-20) on 10 mg donepezil QD. Patients received ST101 (10, 60, or 120 mg QD) or placebo for 12 weeks. The primary endpoint was change in cognitive function measured by ADAS-cog in the modified Intent To Treat (MITT) population and the Per Protocol (PP) population. Results Mean ADAS-cog change favored ST101 over placebo in the MITT population (p = 0.0957, one-sided) and in the PP population (p = 0.0434, one-sided, ∼1.5 point drug-placebo difference) comparing all ST101 dose groups combined to placebo. Among secondary and exploratory outcome measures the ADCS-CGIC also showed a beneficial trend (p = 0.0294, one-sided). In a post-hoc analysis, the subgroup with more severe disease (MMSE 10-17) showed a dose response in the ADAS-cog with the greatest efficacy at 120 mg (p = 0.0067, one sided). No significant ST101-related safety concerns were identified. Conclusion The study supports the possibility that ST101, in patients receiving a stable dose of donepezil, may provide additional symptomatic benefit in moderate AD.

Importance Edonerpic maleate (T-817MA) protects against Aβ40-induced neurotoxic effects and memory deficits, promotes neurite outgrowth, and preserves hippocampal synapses and spatial memory in tau transgenic mice. These effects may be mediated via sigma-1 receptor activation, delivery of synaptic AMPA receptors, or modulation of microglial function and may benefit patients with Alzheimer disease. Objective To assess the efficacy, safety, and tolerability of edonerpic for patients with mild to moderate Alzheimer disease. Design, Setting, and Participants Randomized, double-blind, placebo-controlled, parallel-group, phase 2 clinical trial conducted over 52 weeks from June 2, 2014, to December 14, 2016, at 52 US clinical and academic centers. Of 822 outpatients screened, 484 met the following criteria and were randomly assigned to treatment: 55 to 85 years of age, probable Alzheimer disease, Mini-Mental State Examination scores from 12 to 22, and taking stable doses of donepezil or rivastigmine with or without memantine. Interventions Random assignment (1:1:1 allocation) to placebo or 224 mg or 448 mg of edonerpic maleate, once per day. Main Outcomes and Measures Coprimary outcomes were scores on the Alzheimer Disease Assessment Scale–Cognitive Subscale (ADAS-cog) and Alzheimer’s Disease Cooperative Study–Clinical Impression of Change (ADCS-CGIC) at week 52. Biomarkers were brain, lateral ventricular, and hippocampal volumes, as determined on magnetic resonance imaging, and cerebrospinal fluid Aβ40, Aβ42, total tau, and phospho-tau181. The primary efficacy analysis was performed on the coprimary end points for the modified intention-to-treat population. Results Of 482 participants in the safety population, 140 of 158 participants (88.6%) assigned to placebo, 117 of 166 participants (70.5%) to 224 mg of edonerpic maleate, and 120 of 158 participants (76.0%) to 448 mg of edonerpic maleate completed the trial. The mean ADAS-cog score change at week 52 was 7.91 for the placebo group, 7.45 for the 224-mg group, and 7.08 for the 448-mg group. Mean differences from placebo were −0.47 (95% CI, −2.36 to 1.43;P = .63) for the 224-mg group and −0.84 (95% CI, −2.75 to 1.08;P = .39) for the 448-mg group. Mean ADCS-CGIC scores were 5.22 for the placebo group, 5.24 for the 224-mg group, and 5.25 for the 448-mg group, with mean differences from placebo of 0.03 (95% CI, −0.20 to 0.25;P = .81) for the 224-mg group and 0.04 (95% CI, −0.19 to 0.26;P = .76) for the 448-mg group. In the safety population, a total of 7 of 158 participants (4.4%) in the placebo group, 23 of 166 participants (13.9%) in the 224-mg group, and 23 of 158 participants (14.6%) in the 448-mg group discontinued because of adverse events. The most frequent adverse events were diarrhea and vomiting. Conclusions and Relevance Edonerpic maleate appeared to be safe and tolerable, with expected gastrointestinal symptoms occurring early but without evidence for a clinical effect among patients with mild to moderate Alzheimer disease. Trial Registration ClinicalTrials.gov identifier:NCT02079909

Increased rates of apoptosis (programmed cell death) have been demonstrated in many hepatic diseases including chronic hepatitis C. IDN-6556 is a potent inhibitor of caspases, the proteases that execute apoptosis. In a prior phase 1 study, IDN-6556 lowered aminotransferase activity in a small number of patients with liver impairment. The purpose of this study was to further explore the effect of IDN-6556 in patients with liver disease in a multicenter, double-blind, placebo-controlled, dose-ranging study with a 14-day dosing period. A total of 105 patients were enrolled in the study; 79 received active drug; 80 patients had chronic hepatitis C and 25 had other liver diseases including nonalcoholic steatohepatitis (NASH), hepatitis B, primary biliary cirrhosis (PBC), and primary sclerosing cholangitis (PSC). IDN-6556 doses ranged from 5 mg to 400 mg daily, given from 1 to 3 times per day. In the HCV patients, all doses of IDN-6556 significantly lowered ALT and AST (P = 0.0041 to P < 0.0001 for various dosing groups in Wilcoxon tests comparing IDN-6556 to placebo), with the exception of the lowest dose. Declines in aminotransferase activity were also seen in patients with NASH but effects were not apparent in the small number of other liver diseases. Adverse experiences were not different between IDN-6556 and placebo. There were no clinically meaningful changes in other laboratory parameters. In particular, mean HCV RNA levels did not show significant changes. Conclusion: Oral IDN-6556, given for 14 days, significantly lowered aminotransferase activity in HCV patients and appeared to be well tolerated. Longer studies to assess potential effects of IDN-6556 on liver inflammation and fibrosis are merited. (HEPATOLOGY 2007.)

We describe a series of potent and selective oxindole–pyridine-based protein kinase B/Akt inhibitors. The most potent compound 11n in this series demonstrated an IC50 of 0.17 nM against Akt1 and more than 100-fold selectivity over other Akt isozymes. The selectivity against other protein kinases was highly dependent on the C-3 substitutions at the oxindole scaffold, with unsubstituted 9e or 3-furan-2-ylmethylene (11n) more selective and 3-(1H-pyrrol-2-yl)methylene (11f) or 3-(1H-imidazol-2-yl)methylene (11k) less selective. In a mouse xenograft model, 9d, 11f, and 11n inhibited tumor growth but with accompanying toxicity.

The structure–activity relationships of a series of isoquinoline–pyridine-based protein kinase B/Akt antagonists have been investigated in an effort to improve the major short-comings of the lead compound 3, including poor pharmacokinetic profiles in several species (e.g., mouse iv t1/2 = 0.3 h, po F = 0%). Chlorination at C-1 position of the isoquinoline improved its pharmacokinetic property in mice (iv t1/2 = 5.0 h, po F = 51%) but resulted in >500-fold drop in potency. In a mouse MiaPaCa-2 xenograft model, an amino analog 10y significantly slowed the tumor growth, however was accompanied by toxicity.

Structure-based design and synthesis of the 3,4'-bispyridinylethylene series led to the discovery of 3-isoquinolinylpyridine 13a as a potent PKB/Akt inhibitor with an IC(50) of 1.3nM against Akt1. Compound 13a shows excellent selectivity against distinct families of kinases such as tyrosine kinases and CAMK, and displays poor to marginal selectivity against closely related kinases in the AGC and CMGC families. Moreover, 13a demonstrates potent cellular activity comparable to staurosporine, with IC(50) values of 0.42 and 0.59microM against MiaPaCa-2 and the Akt1 overexpressing FL5.12-Akt1, respectively. Inhibition of phosphorylation of the Akt downstream target GSK3 was also observed in FL5.12-Akt1 cells with an EC(50) of 1.5microM. The X-ray structures of 12 and 13a in complex with PKA in the ATP-binding site were determined.

The Akt kinases are central nodes in signal transduction pathways that are important for cellular transformation and tumor progression. We report the development of a series of potent and selective indazole-pyridine based Akt inhibitors. These compounds, exemplified by A-443654 (Ki = 160 pmol/L versus Akt1), inhibit Akt-dependent signal transduction in cells and in vivo in a dose-responsive manner. In vivo, the Akt inhibitors slow the progression of tumors when used as monotherapy or in combination with paclitaxel or rapamycin. Tumor growth inhibition was observed during the dosing interval, and the tumors regrew when compound administration was ceased. The therapeutic window for these compounds is narrow. Efficacy is achieved at doses ∼2-fold lower than the maximally tolerated doses. Consistent with data from knockout animals, the Akt inhibitors induce an increase in insulin secretion. They also induce a reactive increase in Akt phosphorylation. Other toxicities observed, including malaise and weight loss, are consistent with abnormalities in glucose metabolism. These data show that direct Akt inhibition may be useful in cancer therapy, but significant metabolic toxicities are likely dose limiting.

Proteins in the Bcl-2 family are central regulators of programmed cell death, and members that inhibit apoptosis, such as Bcl-X(L) and Bcl-2, are overexpressed in many cancers and contribute to tumour initiation, progression and resistance to therapy. Bcl-X(L) expression correlates with chemo-resistance of tumour cell lines, and reductions in Bcl-2 increase sensitivity to anticancer drugs and enhance in vivo survival. The development of inhibitors of these proteins as potential anti-cancer therapeutics has been previously explored, but obtaining potent small-molecule inhibitors has proved difficult owing to the necessity of targeting a protein-protein interaction. Here, using nuclear magnetic resonance (NMR)-based screening, parallel synthesis and structure-based design, we have discovered ABT-737, a small-molecule inhibitor of the anti-apoptotic proteins Bcl-2, Bcl-X(L) and Bcl-w, with an affinity two to three orders of magnitude more potent than previously reported compounds. Mechanistic studies reveal that ABT-737 does not directly initiate the apoptotic process, but enhances the effects of death signals, displaying synergistic cytotoxicity with chemotherapeutics and radiation. ABT-737 exhibits single-agent-mechanism-based killing of cells from lymphoma and small-cell lung carcinoma lines, as well as primary patient-derived cells, and in animal models, ABT-737 improves survival, causes regression of established tumours, and produces cures in a high percentage of the mice.

Studies of Drosophila and mammals have revealed the importance of insulin signaling through phosphatidylinositol 3-kinase and the serine/threonine kinase Akt/protein kinase B for the regulation of cell, organ, and organismal growth. In mammals, three highly conserved proteins, Akt1, Akt2, and Akt3, comprise the Akt family, of which the first two are required for normal growth and metabolism, respectively. Here we address the function of Akt3. Like Akt1, Akt3 is not required for the maintenance of normal carbohydrate metabolism but is essential for the attainment of normal organ size. However, in contrast to Akt1-/- mice, which display a proportional decrease in the sizes of all organs, Akt3-/- mice present a selective 20% decrease in brain size. Moreover, although Akt1- and Akt3-deficient brains are reduced in size to approximately the same degree, the absence of Akt1 leads to a reduction in cell number, whereas the lack of Akt3 results in smaller and fewer cells. Finally, mammalian target of rapamycin signaling is attenuated in the brains of Akt3-/- but not Akt1-/- mice, suggesting that differential regulation of this pathway contributes to an isoform-specific regulation of cell growth.

We have examined the effects of truncated Bid (tBid) and ceramide on mitochondrial membrane integrity and cytochrome c release, using mitochondria with intact outer membranes. While tBid permeabilizes the outer membrane and efficiently stimulates cytochrome c release, digitonin is unable to cause cytochrome c release in the absence of salt. Ceramides did not permeabilize the mitochondrial outer membrane, and stimulated cytochrome c release only in the presence of digitonin. Taken together, these observations support a model for cytochrome c release in which the first step is dissociation from the inner membrane followed by transit across the outer membrane.

TPS11626 Background: Ewing sarcoma (ES) is a rare cancer that affects children and young adults. Patients with recurrent/refractory ES have a poor prognosis (5-year survival 10-15%) with no improvement despite advances in cytotoxic and targeted therapies. Genomic rearrangements resulting in fusion proteins and over-expression of ets family transcription factors occur in 95% of ES. In particular, the EWS-FLI1 oncogenic fusion creates a constitutively active transcription factor that drives the malignant ES phenotype. Strategies to target the EWS-FLI1 fusion protein have been limited by lack of specificity. A promising approach is to target the interaction of the ets transcription factor with its critical protein partner, RNA helicase A (RHA). TK216 is a novel small-molecule that directly binds to EWS-FLI1 and inhibits its function by blocking binding to RHA. TK216 demonstrates potent anti-proliferative effects on ES cell lines and xenografts. Methods: We initiated a Phase 1, first-in-human, open-label, multi-center, dose-escalation/dose-expansion trial of TK216 in patients with recurrent/refractory ES who are ≥12 years of age (ClinicalTrials.gov: NCT02657005). TK216 is dosed based on body surface area and administered as a continuous intravenous infusion for 7 days followed by 14 days rest every 21 days. Treatment may continue in the absence of disease progression. One intrapatient dose escalation is allowed. Enrollment of 6 to 8 cohorts using a 3+3 dose-escalation design is anticipated. During dose expansion, a total of 18 patients with ES will be accrued at the recommended Phase 2 dose (RP2D). The primary objective of the study is to determine the maximum tolerated dose and RP2D of TK216. Secondary objectives are to assess the safety profile, pharmacokinetics, pharmacodynamics, and antitumor activity of TK216. Molecular assays will be performed to characterize EWS-FLI or EWS-ets abnormalities in archival tumor tissue. The overall response rate, duration of response, progression-free survival, and overall survival will be determined in the expansion cohort. Nine patients have been enrolled since June 2016. Accrual to cohorts 1, 2, and 3 completed and cohort 4 opened in January 2017. Clinical trial information: NCT02657005.

Bad, an inducer of programmed cell death, was recently isolated from a mouse cDNA library by its ability to bind to the anti-apoptotic protein BCL-2. Sequence analysis suggested that Bad was a member of the BCL-2 gene family that encodes both inducers and inhibitors of programmed cell death. To further analyze the role of BAD in the network of homo- and heterodimers formed by the BCL-2 family, we have cloned the human homologue of BAD and assessed its biological activity and its interactions with wild type and mutant BCL-2 family proteins. Our results indicate that the human BAD protein, like its mouse homologue, is able to induce apoptosis when transfected into mammalian cells. Furthermore, in yeast two-hybrid assays as well as quantitative in vitro interaction assays, human Bad interacted with BCL-2 and BCL-XL. Sequence alignments of human BAD revealed the presence of a BH-3 homology domain as seen in other BCL-2 family proteins. Peptides derived from this domain were able to completely inhibit the dimerization of BAD with BCL-XL. Thus, as previously shown for BAX, BAK, BCL-2, and BCL-XL, the BH3 domain of BAD is required for its dimerization with other BCL-2 family proteins. BAD was further analyzed for its ability to bind to various mutants of BCL-2 and BCL-XL that have lost the ability to bind BAX and BAK, some of which retain biological activity and some of which do not. Surprisingly, all of the mutated BCL-2 and BCL-XL proteins analyzed strongly interacted with human BAD. Our data thus indicate that mutations in BCL-2 and BCL-XL can differentially affect the heterodimeric binding of different death-promoting proteins and have implications concerning the relationship between heterodimerization and biological activity.

We have identified and isolated both the rat and human cDNAs for a novel putative receptor related to the interleukin-1 type 1 receptor. We have named this protein interleukin 1 receptor related protein two (IL 1R-rp2). The rat cDNA for IL1R-rp2 was first identified using oligonucleotides of degenerate sequence in a polymerase chain reaction (PCR) paradigm with rat brain mRNA as the template. The protein encoded by both of these cDNAs are 561 amino acids long and exhibit 42% and 26% overall identity with the interleukin-1 type 1 and type 2 receptors, respectively. RNase protection assays from rat tissues revealed a predominant expression for IL 1R-rp2 in the lung and epididymis with lower levels detected in the testis and cerebral cortex. By in situ hybridization we were able to determine that the expression in rat brain appeared to be non-neuronal and associated with the cerebral vasculature. When expressed transiently in COS-7 cells the receptor was incapable of high affinity binding to either [125I]-recombinant human IL 1 alpha or [125I]-recombinant human IL 1 beta. Together, these data demonstrate the existence of a novel protein that is related to the interleukin-1 receptor but does not bind IL-1 by itself.

The amyloid forming beta-peptide of Alzheimer's disease is synthesized as part of a larger integral membrane precursor protein (beta APP) of which three alternatively spliced versions of 695, 751, and 770 amino acids have been described. A fourth beta APP form of 563 amino acids does not contain the beta-peptide region. Recent experiments using transient expression in HeLa cells (Weidemann, A., Konig, G., Bunke, D., Fischer, P., Salbaum, J.M., Masters, C.L., and Beyreuther, K. (1989) Cell 57, 115-126) indicate that the beta APP undergoes several posttranslational modifications including the cleavage and secretion of a large portion of its extracellular domain. The nature and fate of the fragment that remains cell-associated following this cleavage has not heretofore been described. The metabolism of this fragment may have particular significance in Alzheimer's disease since it must contain at least part of the beta-peptide. To study the metabolic fate of this fragment, we have established cell lines overexpressing the 695- and 751-amino acid versions of beta APP. Pulse-chase studies show that this system is similar to the HeLa cell system in that both proteins are synthesized first as membrane-bound proteins of approximately 98 and 108 kDa carrying asparagine-linked sugar side chains and are subsequently processed into higher molecular mass forms by the attachment of sulfate, phosphate, and further sugar groups including sialic acid, adding approximately 20 kDa in apparent molecular mass. The mature form of beta APP is cleaved and rapidly secreted, leaving an 11.5-kDa fragment with the transmembrane region and the cytoplasmic domain behind in the cell. This fragment is stable with a half-life of at least 4 h.

Overexpression of the antiapototic proteins Bcl-2 and Bcl-xL provides a common mechanism through which cancer cells gain a survival advantage and become resistant to conventional chemotherapy. Inhibition of these prosurvival proteins is an attractive strategy for cancer therapy. We recently described the discovery of a selective Bcl-xL antagonist that potentiates the antitumor activity of chemotherapy and radiation. Here we describe the use of structure-guided design to exploit a deep hydrophobic binding pocket on the surface of these proteins to develop the first dual, subnanomolar inhibitors of Bcl-xL and Bcl-2. This study culminated in the identification of 2, which exhibited EC50 values of 8 nM and 30 nM in Bcl-2 and Bcl-xL dependent cells, respectively. Compound 2 demonstrated single agent efficacy against human follicular lymphoma cell lines that overexpress Bcl-2, and efficacy in a murine xenograft model of lymphoma when given both as a single agent and in combination with etoposide.

Inhibition of the prosurvival members of the Bcl-2 family of proteins represents an attractive strategy for the treatment of cancer. We have previously reported the activity of ABT-737, a potent inhibitor of Bcl-2, Bcl-XL, and Bcl-w, which exhibits monotherapy efficacy in xenograft models of small-cell lung cancer and lymphoma and potentiates the activity of numerous cytotoxic agents. Here we describe the biological activity of A-385358, a small molecule with relative selectivity for binding to Bcl-XL versus Bcl-2 (Ki's of 0.80 and 67 nmol/L for Bcl-XL and Bcl-2, respectively). This compound efficiently enters cells and co-localizes with the mitochondrial membrane. Although A-385358 shows relatively modest single-agent cytotoxic activity against most tumor cell lines, it has an EC50 of

A series of heteroaryl-pyridine containing inhibitors of Akt are reported. The synthesis and structure–activity relationships are discussed, leading to the discovery of a indazole-pyridine analogue (Ki = 0.16 nM). These compounds bind in the ATP binding site, are potent, ATP competitive, and reversible inhibitors of Akt activity. No selectivity amongst the Akt isoforms is observed for this analogue, but there is good selectivity against an panel of other kinases. It is least selective for other members of the AGC family of kinases but is nonetheless 40-fold selective for Akt over PKA. The compound shows cellular activity and significantly slows tumor growth in vivo.

Development of a rationally designed potentiator of cancer chemotherapy, via inhibition of Bcl-X(L) function, is described. Lead compounds generated by NMR screening and directed parallel synthesis displayed sub-microM binding but were strongly deactivated in the presence of serum. The dominant component of serum deactivation was identified as domain III of human serum albumin (HSA); NMR solution structures of inhibitors bound to both Bcl-X(L) and HSA domain III indicated two potential optimization sites for separation of affinities. Modifications at both sites resulted in compounds with improved Bcl-X(L) binding and greatly increased activity in the presence of human serum, culminating in 73R, which bound to Bcl-X(L) with a K(i) of 0.8 nM. In a cellular assay 73R reversed the protection afforded by Bcl-X(L) overexpression against cytokine deprivation in FL5.12 cells with an EC(50) of 0.47 microM. 73R showed little effect on the viability of the human non small cell lung cancer cell line A549. However, consistent with the proposed mechanism, 73R potentiated the activity of paclitaxel and UV irradiation in vitro and potentiated the antitumor efficacy of paclitaxel in a mouse xenograft model.

A novel series of Akt/PKB inhibitors derived from a screening lead (1) has been prepared. The novel trans-3,4′-bispyridinylethylenes described herein are potent inhibitors of Akt/PKB with IC50 values in the low double-digit nanomolar range against Akt1. Compound 2q shows excellent selectivity against distinct families of kinases such as tyrosine kinases and CAMK, and displays poor to modest selectivity against closely related kinases in the AGC and CMGC families. The cellular activities including inhibition of cell growth and phosphorylation of downstream target GSK3 are also described. The X-ray structure of compound 2q complexed with PKA in the ATP binding site was determined.

Akt is a serine/threonine kinase that plays a critical role in cell survival and proliferation. Three isoforms of Akt have been identified and have been shown to be up-regulated in human malignancies. We examined the requirement of these pathways for Akt transformation. We generated NIH-3T3 cells over-expressing constitutively active Myr-Akt1 (3T3-Akt1 cells) or Myr-Akt2 (3T3-Akt2 cells). These cells are able to form colonies in soft-agar and 3T3-Akt1 cells formed tumors in SCID mice. Rapamycin efficiently inhibited the activation of the mTOR-p70S6K pathway and the anchorage-independent growth of both 3T3-Akt cells, demonstrating the importance of the mTOR-p70S6K pathway for transformation by Akt1 as well as by Akt2. Moreover, rapamycin dramatically inhibited the tumor formation by 3T3-Akt1 cells in SCID mice. Thus, we demonstrated the importance of mTOR-p70S6 kinase pathway in the transformation by Akt, both in tissue-cultured cells and in animal tumor models. In contrast, neither the MAPK pathway nor the p38 MAPK pathway is required for Akt-dependent transformation of NIH3T3 cells.

Inhibitor of apoptosis (IAP) proteins are overexpressed in many cancers and have been implicated in tumor growth, pathogenesis, and resistance to chemo- or radiotherapy. On the basis of the NMR structure of a SMAC peptide complexed with the BIR3 domain of X-linked IAP (XIAP), a novel series of XIAP antagonists was discovered. The most potent compounds in this series bind to the baculovirus IAP repeat 3 (BIR3) domain of XIAP with single-digit nanomolar affinity and promote cell death in several human cancer cell lines. In a MDA-MB-231 breast cancer mouse xenograft model, these XIAP antagonists inhibited the growth of tumors. Close structural analogues that showed only weak binding to the XIAP-BIR3 domain were inactive in the cellular assays and showed only marginal in vivo activity. Our results are consistent with a mechanism in which ligands for the BIR3 domain of XIAP induce apoptosis by freeing up caspases. The present study validates the BIR3 domain of XIAP as a target and supports the use of small molecule XIAP antagonists as a potential therapy for cancers that overexpress XIAP.

Progressive cerebral deposition of the 39-43-amino-acid amyloid beta-protein (A beta) is an invariant feature of Alzheimer's disease which precedes symptoms of dementia by years or decades. The only specific molecular defects that cause Alzheimer's disease which have been identified so far are missense mutations in the gene encoding the beta-amyloid precursor protein (beta-APP) in certain families with an autosomal dominant form of the disease (familial Alzheimer's disease, or FAD). These mutations are located within or immediately flanking the A beta region of beta-APP, but the mechanism by which they cause the pathological phenotype of early and accelerated A beta deposition is unknown. Here we report that cultured cells which express a beta-APP complementary DNA bearing a double mutation (Lys to Asn at residue 595 plus Met to Leu at position 596) found in a Swedish FAD family produce approximately 6-8-fold more A beta than cells expressing normal beta-APP. The Met 596 to Leu mutation is principally responsible for the increase. These data establish a direct link between a FAD genotype and the clinicopathological phenotype. Further, they confirm the relevance of the continuous A beta production by cultured cells for elucidating the fundamental mechanism of Alzheimer's disease.

Protective effects after focal cerebral ischemia were assessed in transgenic mice that overexpress in a neuron-specific fashion mouse Bcl-X L or human Bcl-2 . Both Bcl genes were under the control of the same mouse Thy-1 regulatory sequences resulting in very similar expression patterns in cortical neurons. Furthermore, these sequences direct late-onset (i.e. around birth) expression in brain, thus minimizing effects of transgene expression during brain development. Effects on infarct volume were measured using MRI after permanent occlusion of the middle cerebral artery (MCA). When compared to their non-transgenic littermates, Thy1mbcl-X L mice showed a significant 21% reduction in infarct size whereas Thy1hbcl-2 mice did not reveal any reduction. These findings suggest a selective protective advantage of Bcl-X L as compared with Bcl-2 in this mouse model for human stroke.

The genes ced-3, ced-4 and ced-9 are central components in the cell death pathway of the nematode C. elegans. Ced-9, which functions to inhibit cell death, is homologous to the Bcl-2 family of mammalian anti-apoptotic genes. The ced-3 gene encodes a protein homologous to the caspases, a family of cysteine proteases involved in the execution of programmed cell death. It has recently been demonstrated that CED-4, an inducer of apoptosis for which no mammalian equivalent has been reported, can interact with CED-9 and Bcl-x(L). Here we confirm that CED-9 and CED-4 interact and using a series of deletion mutants, demonstrate that only short N-terminal deletions are tolerated in each molecule without loss-of-interaction. Two loss-of-function point mutations in different regions of CED-4 also lead to a significant loss of interaction suggesting further that the relevant interaction domains are not short linear sequences, but rather, are formed by more complex structural determinants in each molecule. Furthermore, we demonstrate that CED-4 not only interacts with Bcl-x(L) but also with its homologue, Bcl-2, and that the unstructured loop region present in Bcl-x(L) and Bcl-2 can regulate the CED-4 interaction. Lastly, we show that a BH3 peptide that can inhibit Bcl-2 family interactions also inhibits the interaction between Bcl-x(L) and CED-4.

Interactions among proteins in the Bcl-2 family regulate the onset of programmed cell death. Previous work has shown that the death-inhibiting family members Bcl-2 and Bcl-xL form heterodimers with the death-promoting homologue Bax and that certain site-directed mutants of Bcl-2 and Bcl-xL lose both biological activity and the ability to bind Bax. To better understand the structural basis of heterodimer formation, we have used a yeast two-hybrid assay to screen for mutants of Bax that regain the ability to bind to these inactive Bcl-2(G145A) and Bcl-xL(G138A) mutants. This screen identified a series of C-terminally truncated Bax molecules that contain complete BH3 (Bcl-2 homology domain 3) domains but that have lost BH1 and BH2 sequences. These results indicate that while the Bcl-2 and Bcl-xL mutants fail to bind full-length Bax, they still retain a binding site for the critical BH3 domain. This suggests that conformational constraints in full-length Bax regulate its ability to bind to other Bcl-2 family members. Furthermore, we demonstrate that the normally inert Bcl-2(G145A) mutant effectively blocks apoptosis induced by a C-terminally truncated Bax molecule, but does not block apoptosis induced by wild-type Bax. This demonstrates that cell protection can be effected by directly binding pro-apoptotic members of the Bcl-2 family.

Bcl-2 inhibits apoptosis induced by a wide variety of stimuli. In contrast, the Bcl-2 homologue, Bax, antagonizes Bcl-2's death protecting function. Bcl-2 forms protein-protein homodimers with itself and heterodimers with Bax, and previous experiments have shown that point mutations in Bcl-2 can abrogate Bax binding while leaving homodimerization intact. These mutagenesis results can be interpreted to suggest that Bcl-2 has separate binding sites that are responsible for homodimer and heterodimer formation. Results from yeast two-hybrid studies have also suggested that homodimerization and heterodimerization reflect distinct modes of interaction. However, using quantitative plate binding assays, we now show that Bax as well as peptides derived from the BH3 domains of Bax and Bak block both Bcl-2/Bax binding and Bcl-2/Bcl-2 binding. Similar assays demonstrate that Bcl-xL can form both homodimers and heterodimers and that these interactions are also inhibited by Bax and the BH3-derived peptides. These results demonstrate that the same binding motifs are responsible for both homodimerization and heterodimerization of Bcl-2 family members.

Alzheimer's disease is characterized by the extracellular deposition of beta-amyloid peptide (Abeta) in cerebral plaques and evidence is accumulating that amyloid is neurotoxic. Abeta is derived from the beta-amyloid precursor protein (APP). Proteolytic processing of APP by the enzyme, beta-secretase, produces the N terminus of Abeta, and releases a secreted ectodomain of APP (beta-s-APP). To develop animal models for measuring beta-secretase activity in specific brain cells in vivo, we have targeted the expression of the full-length human APP to either neurons or astrocytes in transgenic mice using the neuron- specific enolase (NSE) promoter or a modified glial fibrillary acidic protein (GFAP) gene, respectively. The APP cDNAs expressed were mutated (KM to NL at 670/671) to encode amino acid substitutions that enhance amyloidogenic processing in vitro. Western analyses revealed abundant production of beta-s-APP in the brains of NSE-APP mice and enzyme-linked immunosorbent assay analyses showed production of Abeta in fetal primary mixed brain cultures and brain homogenates from these transgenic animals. Because the NSE promoter drives expression primarily in neurons, this provides in vivo evidence that the beta-secretase cleavage necessary for generation of beta-s-APP and Abeta is efficiently performed in neurons. In contrast, only little beta-s-APP was detected in brain homogenates of GFAP-APP mice, indicating that astrocytes show very little beta-secretase activity in vivo. This provides strong in vivo evidence that the major source of Abeta in brain is from neurons and not from astrocytes.

Two CRF receptor subtypes (CRF1 and CRF2 receptors) with distinct brain localizations and pharmacological profiles have recently been cloned and characterized. For the CRF2 receptor subtype, at least 2 splice forms with different 5'-coding sequences (CRF2 alpha and CRF2 beta) have been identified in rat. In this article, we report the genomic structure and the corresponding complementary DNA (cDNA) sequence of the human CRF2 receptor. The gene coding for human CRF2 receptor consists of at least 12 exons and spans approximately 30 kilobases. The cDNA sequence in the protein-coding region is 94% identical to that of the reported rat CRF2 alpha receptor. At present, there is no evidence for the existence of a CRF2 beta receptor homolog in humans. The encoded receptor is 411 amino acids in length and is 70% identical to the human CRF1 receptor, with least sequence homology in the N-terminal extracellular domain (47% identical). Cells transfected with the full-length human CRF2 receptor cDNA responded to rat/human CRF and sauvagine by increasing the intracellular cAMP level, with EC50 values of approximately 20 and 1 nM, respectively. The CRF- and sauvagine-induced accumulation of intracellular cAMP could be competitively inhibited by the CRF receptor antagonist D-Phe-CRF. This pharmacological profile was comparable to that of the rat CRF2 alpha receptor. The relative abundance of the CRF2 receptor messenger RNA appears to be lower in humans than in rats for the tissues studied thus far.

The present study reports the isolation of a cDNA clone that encodes a second member of the corticotropin-releasing factor (CRF) receptor family, designated as the CRF2 receptor. The cDNA was identified using oligonucleotides of degenerate sequence in a PCR paradigm. A PCR fragment obtained from rat brain was utilized to isolate a full-length cDNA from a rat hypothalamus cDNA library that encoded a 411-amino acid protein with approximately 70% identity to the known CRF1 receptor over the entire coding region. When expressed in mouse Ltk- cells, this receptor stimulates cAMP production in response to CRF and known CRF-like agonists. CRF and the nonmammalian CRF-related peptides sauvagine and urotensin I stimulate adenylate cyclase activity in a dose-dependent manner with a rank order of potency different from that of the CRF1 receptor: sauvagine > urotensin > or = rat/human CRF > ovine CRF. Tissue distribution analysis of the mRNAs by reverse transcriptase-PCR shows CRF2 receptor mRNA is present in rat brain and detectable in lung and heart. In situ hybridization studies indicate specific expression within the brain in the ventromedial nuclei of the hypothalamus, the lateral septum, the amygdala, and entorhinal cortex, but there is unremarkable expression in the pituitary. An additional splice variant of the CRF2 receptor with a different N-terminal domain has been identified by PCR, encoding a putative protein of 431 amino acids. Thus, the data demonstrate the presence of another functional CRF receptor, with significant differences in the pharmacological profile and tissue distribution from the CRF1 receptor, which would predict important functional differences between the two receptors.

The expression of the carboxyl-terminal 100 (C-100) residues of the amyloid precursor protein (APP) may provide a model for studying the processing of APP to the 42–43 residue β-amyloid peptide (βA4) implicated in Alzheimer's disease. Expression of human C-100 in mammalian cells reportedly causes ‘toxicity’ and amyloid-like fibrils. We have expressed the C-100 fragment in human embryonic kidney cells (293 cells) in a transient assay and compared it to the expression of transfected wild type and mutant (Swedish familial Alzheimer's disease) full length APP. Products were characterized by Western blot analysis using antibodies to the carboxyl-terminal region of APP.

Based upon recent evidence that the secreted form of APP can cause the release of cytokines and elicit other biological activities, we sought to identify whether a receptor could be identified on the surface of cells. The secreted amyloid precursor protein containing the Kunitz domain (scAPP 751 ) is identical to protease nexin II, a protease inhibitor which has been shown to form complexes with labeled EGF binding protein that subsequently binds to cells. Results of [ 125 I]scAPP 751 -trypsin complex incubated with intact fibroblast cells show that the complex appears to bind in a saturable time-dependent and reversible manner. The kinetic constants from the binding studies demonstrate a k 1 = 2.5 × 10 7 M −1 s −1 and k 2 =4.7 × 10 −4 s −1 and thus a K D (=k 2 /k 1 ) = 20 pM. Furthermore, the complex formation of [ 125 I]scAPP 751 with a protease appears to be a requirement for optimal binding. The binding affinity of secreted APP demonstrated in this study is consistent with its potency in eliminating a range of biological efforts that have been documented.

Alzheimer's disease is characterized by the extracellular deposition in the brain and its blood vessels of insoluble aggregates of the amyloid beta peptide (A beta). This peptide is derived from a large integral membrane protein, the beta-amyloid precursor protein (beta APP), by proteolytic processing. The A beta has previously been found only in the brains of patients with Alzheimer's disease or advanced aging. We describe here the finding that A beta is produced continuously by normal processing in tissue culture cells. A beta and closely related peptides were identified in the media of cells transfected with cDNAs coding for beta APP in a variety of cell lines and primary tissue cultured cells. The identity of these peptides was confirmed by epitope mapping and radiosequencing. Peptides of a molecular weight of approximately 3 and approximately 4 kDa are described. The 4 kDa range contains mostly the A beta and two related peptides starting N-terminal to the beginning of A beta. In the 3 kDa range, the majority of peptides start at the secretase site; in addition, two longer peptides were found starting at amino acid F(4) and E(11) of the A beta sequence. To identify the processing pathways which lead to the secretion of these peptides, we used a variety of drugs known to interfere with certain cell biological pathways. We conclude that lysosomes may not play a predominant role in the formation of 3 and 4 kDa peptides. We show that an acidic environment is necessary to create the N-terminus of the A beta and postulate that alternative secretory cleavage might result in the formation of the N-terminus of A beta and related peptides. This cleavage takes place either in the late Golgi, at the cell-surface or in early endosomes, but not in lysosomes. The N-terminus of most of the 3 kDa peptides is created by secretory cleavage on the cell surface or within late Golgi.

The accumulation in brain of senile plaques containing beta-amyloid protein (A beta) is a defining feature of Alzheimer's disease. The amyloid precursor protein (APP)4 from which A beta is derived is subject to several genetic mutations which segregate with rare familial forms of the disease, resulting in early onset of dementia and plaque formation, suggesting that APP metabolism plays a causal role in the disease. Various cell types have been shown to release a soluble form of A beta, thus allowing for the in vitro study of A beta generation. We report here evidence that a substantial portion of the APP secreted by human mixed brain cell cultures, as well as that present in cerebrospinal fluid, is of a novel form cleaved precisely at the amino terminus of A beta, suggesting that a secretory pathway is involved in A beta genesis.

Site-specific mutagenesis techniques have been used to construct active site variants of the Kunitz-type protease inhibitor domain present in the Alzheimer's beta-amyloid precursor protein (APP-KD). Striking alteration of its protease inhibitory properties were obtained when the putative P1 residue, arginine, was replaced with the small hydrophobic residue valine. The altered protein was no longer inhibitory toward bovine pancreatic trypsin, human Factor XIa, mouse epidermal growth factor-binding protein, or bovine chymotrypsin, all of which are strongly inhibited by the unaltered APP-KD (Sinha, S., Dovey, H. F., Seubert, P., Ward, P. J., Blacher, R. W., Blaber, M., Bradshaw, R. A., Arici, M., Mobley, W. C., and Lieberburg, I. (1990) J. Biol. Chem. 265, 8983-8985). Instead, the P1-Val-APP-KD was a potent inhibitor of human neutrophil elastase, with a Ki = 0.8 nM, as estimated by the inhibition of the activity of human neutrophil elastase measured using a chromogenic substrate. It also inhibited the degradation of insoluble elastin by the enzyme virtually stoichiometrically. Replacement of the P1' (Ala) and P2' (Met) residues of P1-Val-MKD with the corresponding residues (Ser, Ile) from alpha 1-proteinase inhibitor resulted in an inactive protein, underscoring the mechanistic differences between the serpins from the Kunitz-type protease inhibitor family. These results confirm the importance of the P1 arginine residue of APP-KD in determining inhibitory specificity, and are also the first time that a single amino acid replacement has been shown to generate a specific potent human neutrophil elastase inhibitor from a human KD sequence.

The amyloid beta peptide (A beta P) is a small fragment of the much larger, broadly distributed amyloid precursor protein (APP). Abundant A beta P deposition in the brains of patients with Alzheimer's disease suggests that altered APP processing may represent a key pathogenic event. Direct protein structural analyses showed that constitutive processing in human embryonic kidney 293 cells cleaves APP in the interior of the A beta P, thus preventing A beta P deposition. A deficiency of this processing event may ultimately prove to be the etiological event in Alzheimer's disease that gives rise to senile plaque formation.

The form of the secreted amyloid β-protein precursor which contains the protease inhibitor sequence is mitogenic for Swiss 3T3 cells, while the precursor molecule lacking the protease inhibitor domain is not. A ten-fold stimulation of DNA synthesis occurs at 8 × 10 −9 M protein.

Human papillomavirus type 7 (HPV-7) was first described in 1981 but so far could not be molecularly cloned. It has been found almost exclusively in hand warts of butchers. We have cloned the complete genome in pBR 322, established its physical map, demonstrated the colinear genome organization with HPV-18 and analyzed the degree of homology with other HPV types and bovine papillomavirus (BPV) types. In order to investigate whether HPV-7 might be a so far unidentified bovine virus, we screened 37 bovine tumor DNAS using Southern blot analysis for its presence, with exclusively negative results. From our data we conclude that the HPV-7 genome shows all characteristics of a papillomavirus genome and that its origin is most likely human.

The cerebral amyloid deposited in Alzheimer's disease (AD) contains a 4.2 kDa beta amyloid polypeptide (beta AP) that is derived from a larger beta amyloid protein precursor (beta APP). Three beta APP mRNAs encoding proteins of 695, 751, and 770 amino acids have previously been identified. In each of these, there is a single membrane-spanning domain close to the carboxyl-terminus of the beta APP, and the 42 amino acid beta AP sequence extends from within the membrane-spanning domain into the large extracellular region of the beta APP. We raised rabbit antisera to a peptide corresponding to amino acids 45-62 near the amino-terminus of the beta APP. We show that these antisera detect the beta APP by demonstrating that they (i) label a set of approximately 120 kDa membrane-associated proteins in human brain previously detected by antisera to the carboxyl-terminus of beta APP and (ii) label a set of approximately 120 kDa membrane-associated proteins that are selectively overexpressed in cells transfected with a full length beta APP expression construct. The beta APP45-62 antisera specifically stain senile plaques in AD brains. This finding, along with the previous demonstration that antisera to the carboxyl-terminus of the beta APP label senile plaques, indicates that both near amino-terminal and carboxyl-terminal domains of the beta APP are present in senile plaques and suggests that proteolytic processing of the full length beta APP molecule into insoluble amyloid fibrils occurs in a highly localized fashion at the sites of amyloid deposition in AD brains.

In this study, we use antisera to synthetic beta-amyloid protein precursor (beta APP) peptides to identify, in human brain and cerebrospinal fluid (CSF), soluble approximately 125- and approximately 105-kDa derivatives of the beta APP that lack the carboxyl terminus of the full-length, membrane-associated forms. We show that the soluble approximately 125-kDa beta APP derivative contains the Kunitz protease inhibitor domain, whereas the approximately 105-kDa form does not, and we confirm that these two proteins are soluble beta APP derivatives by purifying each from human CSF and directly sequencing its amino terminus.

A number of human papillomavirus (HPV) type 16 proteins have recently been identified in human cervical carcinoma cell lines using polyclonal antisera against papillomavirus gene products expressed in Escherichia coli. E7 protein has been found to be the most abundant papillomavirus protein in these cells. Here we describe a panel of monoclonal antibodies recognizing a 15K Mr non-glycosylated cytoplasmic HPV-16 E7 protein. One of the antibodies cross-reacted with HPV-18 E7 protein.

Fibroblasts that harbor an antisense construct of amyloid beta protein precursor (ABPP) cDNA, A-1, produced less ABPP mRNA and ABPP and grew poorly. Normal growth was restored when either parent cell conditioned medium (CM) or purified ABPP was provided. The capacity of the CM to restore cell growth was abolished by passage through an anti-ABPP immunoaffinity column; the activity was in the bound fraction. A Mr 90,000 protein recognized by the anti-ABPP antibody was diminished in the CM of A-1. CM from ABPP cDNA-transfected cells expressing high levels of ABPP was more potent than that from non-transfected parent cells in restoring A-1 growth. These results indicate that ABPP is released from cells into the medium and has an autocrine function in growth regulation.

The A4 protein (or beta-protein) is a 42- or 43-amino-acid peptide present in the extracellular neuritic plaques in Alzheimer's disease and is derived from a membrane-bound amyloid protein precursor (APP). Three forms of APP have been described and are referred to as APP695, APP751 and APP770, reflecting the number of amino acids encoded for by their respective complementary DNAs. The two larger APPs contain a 57-amino-acid insert with striking homology to the Kunitz family of protease inhibitors. Here we report that the deduced amino-terminal sequence of APP is identical to the sequence of a cell-secreted protease inhibitor, protease nexin-II (PN-II). To confirm this finding, APP751 and APP695 cDNAs were over-expressed in the human 293 cell line, and the secreted N-terminal extracellular domains of these APPs were purified to near homogeneity from the tissue-culture medium. The relative molecular mass and high-affinity binding to dextran sulphate of secreted APP751 were consistent with that of PN-II. Functionally, secreted APP751 formed stable, non-covalent, inhibitory complexes with trypsin. Secreted APP695 did not form complexes with trypsin. We conclude that the secreted form of APP with the Kunitz protease inhibitor domain is PN-II.