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Enveloped viruses depend on the host endoplasmic reticulum (ER) quality control (QC) machinery for proper glycoprotein folding. The endoplasmic reticulum quality control (ERQC) enzyme α-glucosidase I (α-GluI) is an attractive target for developing broad-spectrum antivirals. We synthesized 28 inhibitors designed to interact with all four subsites of the α-GluI active site. These inhibitors are derivatives of the iminosugars 1-deoxynojirimycin (1-DNJ) and valiolamine. Crystal structures of ER α-GluI bound to 25 1-DNJ and three valiolamine derivatives revealed the basis for inhibitory potency. We established the structure–activity relationship (SAR) and used the Site Identification by Ligand Competitive Saturation (SILCS) method to develop a model for predicting α-GluI inhibition. We screened the compounds against SARS-CoV-2 in vitroto identify those with greater antiviral activity than the benchmark α-glucosidase inhibitor UV-4. These host-targeting compounds are candidates for investigation in animal models of SARS-CoV-2 and for testing against other viruses that rely on ERQC for correct glycoprotein folding.

All viruses depend on host cell proteins for replication. Denying viruses’ access to the function of critical host proteins can result in antiviral activity against multiple virus families. In particular, small-molecule drug candidates which inhibit the α-glucosidase enzymes of the endoplasmic reticulum (ER) translation quality control (QC) pathway have demonstrated broad-spectrum antiviral activities and low risk for development of viral resistance. However, antiviral drug discovery focused on the ERQC enzyme α-glucosidase I (α-GluI) has been hampered by difficulties in obtaining crystal structures of complexes with inhibitors. We report here the identification of an orthologous enzyme from a thermophilic fungus, Chaetomium thermophilum(Ct), as a robust surrogate for mammalian ER α-GluI and a platform for inhibitor design. Previously annotated only as a hypothetical protein, the Ctprotein was validated as a bona fideα-glucosidase by comparing its crystal structure to that of mammalian α-GluI, by demonstrating enzymatic activity on the unusual α-d-Glcp-(1 → 2)-α-d-Glcp-(1 → 3) substrate glycan, and by showing that well-known inhibitors of mammalian α-GluI (1-DNJ, UV-4, UV-5) also inhibit Ctα-GluI. Crystal structures of Ctα-GluI in complex with three such inhibitors (UV-4, UV-5, EB-0159) revealed extensive interactions with all four enzyme subsites and provided insights into the catalytic mechanism. Identification of ER Ctα-GluI as a surrogate for mammalian α-GluI will accelerate the structure-guided discovery of broad-spectrum antivirals. This study also highlights Ctas a source of thermostable eukaryotic proteins, such as ER α-Glu I, that lack orthologs in bacterial or archaeal thermophiles.

Most enveloped viruses rely on the host cell endoplasmic reticulum (ER) quality control (QC) machinery for proper folding of glycoproteins. The key ER α-glucosidases (α-Glu) I and II of the ERQC machinery are attractive targets for developing broad-spectrum antivirals. Iminosugars based on deoxynojirimycin have been extensively studied as ER α-glucosidase inhibitors; however, other glycomimetic compounds are less established. Accordingly, we synthesized a series of N-substituted derivatives of valiolamine, the iminosugar scaffold of type 2 diabetes drug voglibose. To understand the basis for up to 100,000-fold improved inhibitory potency, we determined high-resolution crystal structures of mouse ER α-GluII in complex with valiolamine and 10 derivatives. The structures revealed extensive interactions with all four α-GluII subsites. We further showed that N-substituted valiolamines were active against dengue virus and SARS-CoV-2 in vitro. This study introduces valiolamine-based inhibitors of the ERQC machinery as candidates for developing potential broad-spectrum therapeutics against the existing and emerging viruses.

Influenza and dengue viruses present a growing global threat to public health. Both viruses depend on the host endoplasmic reticulum (ER) glycoprotein folding pathway. In 2014, Sadat et al.reported two siblings with a rare genetic defect in ER α-glucosidase I (ER Glu I) who showed resistance to viral infections, identifying ER Glu I as a key antiviral target. Here, we show that a single dose of UV-4B (the hydrochloride salt form of N-(9′-methoxynonyl)-1-deoxynojirimycin; MON-DNJ) capable of inhibiting Glu I in vivois sufficient to prevent death in mice infected with lethal viral doses, even when treatment is started as late as 48 h post infection. The first crystal structure of mammalian ER Glu I will constitute the basis for the development of potent and selective inhibitors. Targeting ER Glu I with UV-4B-derived compounds may alter treatment paradigms for acute viral disease through development of a single-dose therapeutic regime.

Most PCs show NE differentiation. Several studies have tried to correlate NE expression with disease status, but the reported findings have been contradictory. Prostatic NE cells synthesize peptides with a wide spectrum of potential functions. Some of these active peptides, such as PAMP, are amidated. PAM is the only carboxy-terminal peptide–amidating enzyme identified. We studied expression of PAMP and PAM in normal prostate and prostatic tumors (clinical specimens and human xenograft models) with or without prior androgen-deprivation therapy and found a wide distribution of both molecules in NE subpopulations of all kinds. Although the correlation of either marker to tumor grade, clinical progression or disease prognosis did not reach statistical significance, PAMP- or PAM-immunoreactive cells were induced after androgen-blockade therapy. In the PC-310 and PC-295 androgen-dependent models, PAMP or PAM NE differentiation was induced after castration in different ways, being higher in PC-310, which might explain its long-term survival after androgen deprivation. We show induction of expression of 2 new NE markers in clinical specimens and xenografted PC after endocrine therapy. © 2001 Wiley-Liss, Inc.

Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP-A2/B1) is highly expressed during critical stages of lung development and carcinogenesis. To determine if the expression of hnRNP-A2/B1 is an informative biomarker in breast carcinogenesis, we analyzed hnRNP-A2/B1 overexpression by immunohistochemistry in archived specimens. Expression was detected in 48/85 (56.5%) primary invasive breast cancers and 7/72 (9.7%) specimens of normal breast tissue. Northern analysis of breast cancer cells also demonstrated higher level of hnRNP-A2/B1 expression compared to normal or transformed breast cells. Expression of hnRNP-A2/B1 in breast cancer cells was decreased by exposure to retinoids coordinately with decreased cell growth. These results warrant further evaluation of hnRNP-A2/B1 as a marker of breast carcinogenesis.

2-Methoxyestradiol, once considered an inacitve end-metabolite of estradiol, has recently emerged as a very promising agent for cancer treatment. It is orally active in a wide range of tumor models, and inhibits tumor growth at doses showing non clinical signs of toxicity. 2ME2targets both the tumor cell and endothelial cell compartments by inducing apoptosis in rapidly proliferating cells and inhibiting blood vessel formation at several stages in the angiogenic cascade. Moreover, the ability of 2ME2to inhibit metastic spread in several models adds to its therapeutic value for cancer treatment at various stages of the disease. Though the mechanism of action is still undefined, several potential molecular targets and pathways of activation have been suggested.

A solid-phase radioimmunoassay utilizing iodinated peptide-specific monoclonal antibody as a detection system instead of labeled peptide has been developed. Regional specific monoclonal antibodies to either gastrin-releasing peptide or gastrin were used as models to validate the general application of our modified assay. Conditions for radioactive labeling of the monoclonal antibody were determined to minimize oxidant damage, which compromises the sensitivity of other reported peptide quantitation assays. Pretreatment of 96-well polyvinyl chloride test plates with a 5% glutaraldehyde solution resulted in consistent retention of sufficient target peptide on the solid-phase matrix to allow precise quantitation. This quantitative method is completed within 1 h of peptide solid phasing. Pretreatment of assay plates with glutaraldehyde increased binding of target peptide and maximized antibody binding by optimizing antigen presentation. The hypothesis that glutaraldehyde affects both peptide binding to the plate and orientation of the peptide was confirmed by analysis of several peptide analogs. These studies indicate that peptide binding was mediated through a free amino group leaving the carboxy-terminal portion of the target peptide accessible for antibody binding. It was observed that the length of the peptide also affects the amount of monoclonal antibody that will bind. Under the optimal conditions, results from quantitation of gastrin-releasing peptide in relevant samples agree well with those from previously reported techniques. Thus, we report here a modified microplate assay which may be generally applied for the rapid and sensitive quantitation of peptide hormones.

Bioactivity of many peptides depends upon post-translational a-amidation of inactive precursors by two enzyme activities known collectively as peptidylglycine a-amidating monooxygenase (PAM). PAM enzymes are particularly abundant in the pituitary. The distribution of PAM immunoreactivity and messenger ribonucleic acid (mRNA) in the adult human pituitary and in pituitary tumours was investigated by use of immunocytochemistry and in situ hybridisation. Immunoreactivity was present in numerous cells of the anterior lobe: staining was intense in a proportion of gonadotrophs and folliculo-stellate cells, but weaker in the majority of somatotrophs and lactotrophs, a few corticotrophs and occasional thyrotrophs. PAM staining was also present in nerves, pituicytes and some endocrine cells within the posterior lobe (the human intermediate zone). Forty pituitary tumours of various types were immunoreactive for PAM; more intensely and uniformly stained than normal anterior lobe. In situ hybridisation with digoxigenin-labelled probes demonstrated intense labelling for PAM mRNA in numerous cells in normal anterior pituitary and in tumours. Many regulatory peptides that require amidation for activity, potential targets for PAM, are present in the pituitary. Many tumour growth factors also require amidation and PAM may regulate these mitogenic peptides in tumours.

5-Ethyl-5-(4-hydroxy-3-methoxyphenyl) barbituric acid was identified as a new, minor metabolite of phenobarbital in man. The identity of this O-methylcatechol metabolite was confirmed by an unequivocal chemical synthesis, and by GC—MS studies. Mephobarbital and the 1,3-dimethyl, 1-ethyl, and 1,3-diethyl analogues of phenobarbital yielded the corresponding N-alkylated O-methylcatechol metabolites, all of which were confirmed by synthesis. The N-alkyl barbiturates each gave additionally at least one O-methylcatechol metabolite in which N-dealkylation had occurred. These metabolites accounted for ∼1–5% of the orally administered dose in man.

Promising cancer clinical trials results involving the disruption of early stages of cancer with intervention agents such as tamoxifen or retinoids have led to significant new research interest in developing preventative strategy for the control of epithelial cancers. Key to the efficient progress in this field is a clear understanding of the complex biology of the early stages of cancerization that proceed on the epithelial surface. Systematic analysis of the biology of strategic targets such as growth factors is one approach to this problem. Gastrin‐releasing peptide is an autocrine growth factor for certain types of lung cancer cells. Mechanisms involved in the production and activation of this peptide are discussed as an example of how rational approaches to neutralization of cancer promotion biology can be achieved. The tools to monitor the success of this type of intervention also emerge from the understanding of the biology of growth factors, and intermediate end point markers that determine the presence or effects of a growth factor are attractive candidates for evaluation. Additional biologic tools reflecting the early stages of the cancer process need to be validated for use in serially evaluating the status of the relevant epithelium so that the ongoing success of a cancer intervention procedure can be established. Through this type of translational research, important applications of molecular biology may greatly improve the success of preventative strategies for cancer control.

The insulin-like growth factors (IGFs), IGF-I and IGF-II, are potent mitogens for human lung and other epithelial cancer cell lines. Previous studies in defined medium lacking added IGF or insulin suggest that an IGF-related ligand can act as an autocrine growth factor for many cancer cell lines through action via the type I IGF receptor (IGF-R). Analysis of RNA isolated from human lung and breast cancer cell lines by reverse transcription of mRNA and polymerase chain reaction reveal that IGF-I and IGF-II mRNAs were co-expressed with IGF-R in the majority of cell lines. IGF-I mRNA was detected in 11/12 small cell lung cancer cell lines (SCLC), 13/14 non-small cell lung cancer (NSCLC) cell lines, and 1/2 breast cancer cell lines. IGF-II mRNA was detected in 8/10 SCLC, 11/12 NSCLC cell lines, and 2/2 breast lines. All cell lines expressed IGF-R. For analysis of IGF peptide secretion, cell lines were adapted to growth in serum/hormone-free culture medium (R0), and to avoid interference by IGF-binding proteins, secreted IGF peptides were isolated under acidic conditions and analyzed by Western blotting. Based upon measurement of the sensitivity of the anti-IGF antibodies for detection of recombinant human IGFs, IGF peptides accumulated in conditioned medium at greater than picomolar concentrations should have been readily detected. In three cell lines (two lung and one breast) secreted IGF immunoreactivity was detected as three molecular mass species of 23, 14, and 6 kDa. Isolation and NH2-terminal sequencing of each of these species definitively identified them as differentially processed forms of the IGF-II prohormone. Despite the high frequency of IGF-I gene expression detected by reverse transcription-polymerase chain reaction analysis, only one lung cancer cell line, NCI-N417d, was found that unequivocally secreted IGF-I peptide. This direct sequence determination unambiguously identifies IGF-II as the predominant IGF involved in the autocrine growth stimulation of human lung and breast epithelial tumor cell lines and supports a growing body of literature that implicates IGF-II/IGF-R autocrine loops as a common growth mechanism in epithelial carcinogenesis.

Burkholderia pseudomallei, the etiological agent of melioidosis, is a Gram-negative bacterium with additional concern as a biothreat pathogen. The mortality rate from B. pseudomalleivaries depending on the type of infection and extent of available health care; in the case of septicemia, left untreated, it can range from 50% to 90%. Current therapy for melioidosis is biphasic, consisting of parenteral acute-phase treatment for 2 weeks or longer, followed by oral eradication-phase treatment lasting several months.

2-Methoxyestradiol (2ME2, Panzem®) is an endogenous metabolite of estradiol with antiproliferative, proapoptotic, and antiangiogenic activity. Some of these activities are mediated through the downregulation of HIF1-α. Panzem® capsules have been evaluated in several oncology clinical trials, including multiple myeloma where some patients have been on therapy for more than 4 years with stable disease. A new formulation of 2ME2 with enhanced absorption, Panzem® NCD, is currently in Phase 1 and 2 clinical studies in oncology. In anticipation of combination studies with Panzem® NCD, we evaluated the effectiveness of 2ME2 alone or with the proteosome inhibitor, Velcade® (bortezomib), in the RPMI-8226 myeloma xenograft tumor model. Preliminary in vitro studies indicated significantly increased antiproliferative activity when 2ME2 (1.5μM) was combined with Velcade® (5nM) compared to Velcade® alone (p<0.05 ANOVA). Additionally, 2ME2 in combination with Velcade® also resulted in decreased nuclear NFκB in response to TNFα, as compared to either agent alone. Subsequent to these studies, female CB17 SCID mice were injected subcutaneously with 1 x 106 RPMI-8226 tumor cells. Starting 10 days after tumor cell inoculation when mean tumor volume was approximately 100–200 mm3, cohorts of mice (n=8/group) began treatment with (a) vehicle alone ad libitum in the drinking water; (b) 2ME2 300 mg/kg ad libitum in the drinking water; (c) Velcade® 1.5 mg/kg i.p., biw; or (d) 2ME2 (300 mg/kg) in combination with Velcade® (1.5 mg/kg). On study day 27, mean tumor volume in vehicle-treated, control mice was approximately 3400 mm3. Under these experimental conditions, treatment with either 2ME2 alone or Velcade® alone generated a treatment/control (T/C) value of 0.66 and 0.64, respectively. In comparison, 2ME2 in combination with Velcade® resulted in a T/C value of 0.35. Velcade® is a well recognized and commonly used antineoplastic agent in multiple myeloma. The degradation of HIF1-α is accomplished through the proteosome. These studies demonstrate that a combination strategy using Velcade® and 2ME2 can enhance the antitumor effectiveness of either agent alone in the treatment of a xenograft model of human multiple myeloma.

2-Methoxyestradiol (2ME2, Panzem®) is an endogenous metabolite of estradiol with antiproliferative, proapoptotic, and antiangiogenic activity. Some of these activities are mediated through the downregulation of HIF1-α. Panzem® capsules have been evaluated in several oncology clinical trials, including multiple myeloma where some patients have been on therapy for more than 4 years with stable disease. A new formulation of 2ME2 with enhanced absorption, Panzem® NCD, is currently in Phase 1 and 2 clinical studies in oncology. In anticipation of combination studies with Panzem® NCD, we evaluated the effectiveness of 2ME2 alone or with the proteosome inhibitor, Velcade® (bortezomib), in the RPMI-8226 myeloma xenograft tumor model. Preliminary in vitro studies indicated significantly increased antiproliferative activity when 2ME2 (1.5μM) was combined with Velcade® (5nM) compared to Velcade® alone (p<0.05 ANOVA). Additionally, 2ME2 in combination with Velcade® also resulted in decreased nuclear NFκB in response to TNFα, as compared to either agent alone. Subsequent to these studies, female CB17 SCID mice were injected subcutaneously with 1 x 106RPMI-8226 tumor cells. Starting 10 days after tumor cell inoculation when mean tumor volume was approximately 100–200 mm3, cohorts of mice (n=8/group) began treatment with (a) vehicle alone ad libitumin the drinking water; (b) 2ME2 300 mg/kg ad libitumin the drinking water; (c) Velcade® 1.5 mg/kg i.p., biw; or (d) 2ME2 (300 mg/kg) in combination with Velcade® (1.5 mg/kg). On study day 27, mean tumor volume in vehicle-treated, control mice was approximately 3400 mm3. Under these experimental conditions, treatment with either 2ME2 alone or Velcade® alone generated a treatment/control (T/C) value of 0.66 and 0.64, respectively. In comparison, 2ME2 in combination with Velcade® resulted in a T/C value of 0.35. Velcade® is a well recognized and commonly used antineoplastic agent in multiple myeloma. The degradation of HIF1-α is accomplished through the proteosome. These studies demonstrate that a combination strategy using Velcade® and 2ME2 can enhance the antitumor effectiveness of either agent alone in the treatment of a xenograft model of human multiple myeloma.

We have evaluated an anti-autocrine growth factor monoclonal antibody for potential use in the treatment of patients with small-cell lung cancer. The monoclonal antibody, designated 2A11, binds to the C-terminal region of the autocrine growth factor gastrin-releasing peptide and neutralizes its growth-promoting effects in vitro and in vivo. Equilibrium-binding analysis demonstrated that the peptide binds to the antibody (dissociation constant = 1.5 × 10−10) at least as avidly as it binds to the tumor peptide receptor. Pharmacokinetic studies in normal BALB/c mice demonstrated an initial clearance half-life (α t1/2] of 243 ± 4 hours and a secondary clearance half-life (β t1/2) of 1039.6 ± 309 hours, and biodistribution studies revealed a distribution pattern which generally reflected blood flow. Single intravenous infusions of 2A11 (20 mg/20–25-kg dogs) into normal mongrel dogs with surgically created gastric fistulas antagonized the stimulatory effects of exogenously infused gastrin-releasing peptide or bombesin on plasma gastrin release and gastric acid secretion. Toxicology studies in normal dogs (with gastric fistulas) infused with 50 mg 2A11 intravenously three times a week for 4 weeks failed to reveal any adverse behavioral, clinical, or pathological effects. Four of six dogs developed an immune response to 2A11. Anti-idiotypic antibodies elicited in two cases did not mimic the functional effects of the peptide. We conclude that the concept of immunoblockade of an autocrine growth factor appears feasible in vivo. [J Natl Cancer Inst 83:1470–1476, 1991]