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Lipid-albumin nanoparticles (LAN) were synthesized for delivery of RX-0047, an antisense oligonucleotide (ASO) against the hypoxia inducible factor-1 alpha (HIF-1α) to solid tumor. These lipid nanoparticles (LNs) incorporated a human serum albumin-pentaethylenehexamine (HSA-PEHA) conjugate, which is cationic and can form electrostatic complexes with negatively charged oligonucleotides. The delivery efficiency of LAN-RX-0047 was investigated in KB cells and a KB murine xenograft model. When KB cells were treated with LAN-RX-0047, significant HIF-1α downregulation and enhanced cellular uptake were observed compared to LN-RX-0047. LN-RX-0047 and LAN-RX-0047 showed similar cytotoxicity against KB cells with IC50 values of 19.3 ± 3.8 and 20.1 ± 4.2 μM, respectively. LAN-RX-0047 was shown to be taken up by the cells via the macropinocytosis and caveolae-mediated endocytosis pathways while LN-RX-0047 was taken up by cells via caveolae-mediated endocytosis. In the KB xenograft tumor model, LAN-RX-0047 exhibited tumor suppressive activity and significantly reduced intratumoral HIF-1α expression compared to LN-RX-0047. Furthermore, LAN-RX-0047 greatly increased survival time of mice bearing KB-1 xenograft tumors at doses of either 3 mg/kg or 16 mg/kg. These results indicated that LAN-RX-0047 is a highly effective vehicle for therapeutic delivery of antisense agents to tumor.

1-(3,5-Dimethoxyphenyl)-4-[(6-fluoro-2-methoxyquinoxalin-3-yl)aminocarbonyl] piperazine (RX-5902) exhibits strong growth inhibition in various human cancer cell lines with IC50 values ranging between 10 and 20 nM. In this study, we demonstrate that p68 RNA helicase is a cellular target of RX-5902 by the drug affinity responsive target stability (DARTS) method, and confirmed the direct binding of 3H-labeled RX-5902 to Y593 phospho-p68 RNA helicase. We further demonstrated RX-5902 inhibited the β-catenin dependent ATPase activity of p68 RNA helicase in an in vitro system. Furthermore, we showed that treatment of cancer cells with RX-5902 resulted in the downregulation of the expression of certain genes, which are known to be regulated by the β-catenin pathway, such as c-Myc, cyclin D1 and p-c-Jun. Therefore, our study indicates that the inhibition of Y593 phospho-p68 helicase - β-catenin interaction by direct binding of RX-5902 to Y593 phospho-p68 RNA helicase may contribute to the anti-cancer activity of this compound. J. Cell. Biochem. 116: 1595–1601, 2015. © 2015 Wiley Periodicals, Inc.

RX-3117 is a novel cytidine analog showing encouraging results in ongoing Phase 2a studies with gemcitabine-resistant pancreatic ductal adenocarcinoma and advanced urothelial bladder cancer. Cellular uptake of RX-3117 is mediated by the equilibrative nucleoside transporter 1 (hENT1). RX-3117 is activated by uridine-cytidine kinase-2 (UCK2) and is not a substrate for cytidine deaminase (CDA), and shows a good oral bioavailability. In an earlier study accumulation of RX-3117 nucleotides was associated with sensitivity to the drug. RX-3117 is incorporated into RNA and DNA and inhibits DNA methyltransferase 1 (DNMT1). RX-3117 is active against gemcitabine-resistant non-small cell lung cancer (NSCLC) cell lines. In this study we aimed to elucidate potential resistance mechanisms against RX-3117. For that purpose the NSCLC cell lines H460, A549 and SW1573 (including its gemcitabine resistant variant SW-G) were exposed to increasing concentrations of RX-3117. For A549 and SW1573 two variants were obtained: A549/RX1, A549/RX2, SW1573/RX1 and SW1573/RX2. Resistance varied from 10 (H460; SW-G) to >100-fold for the other cell lines. Resistance was stable except for H460 cells. Cross-resistance in the same range was observed for the cytidine analogs ethynyl-cytidine (ETC), cyclopentenylcytosine (CPEC) and aza-cytidine (aza-CR), which are all activated by UCK2; no cross-resistance was observed for gemcitabine and aza-deoxycytidine which are activated by deoxycytidine kinase. No change was observed in the expression of DNMT1, while expression of ribonucleotide reductase 1 was decreased. However, analysis of UCK2 at the enzyme activity level, protein and gene expression did not reveal a decrease in UCK2 while for ETC, aza-CR and CPEC resistance was reported to be mediated by a UCK2 deficiency. No change was found in the other activating enzymes UMP-kinase, CMP-kinase and NME1/NDKA. Despite this lack of change, accumulation of RX-3117 and RX-3117 nucleotides (mono-, di- and triphosphate) was 2-5-fold lower in the resistant cells after incubation with 10 or 100 μM RX-3117 for 4-24 hr. No evidence for accumulation of RX-3117 deoxynucleotides was found in both the parent and the resistant cell lines. Since no change in hENT1 was found, cell lines were further investigated by using RNA-seq, and western blotting focusing on nucleoside/nucleotide degradation enzymes. CDA was decreased in resistant cells, but the cytosolic pyrimidine nucleotidase NT5C3 was increased in the resistant cell lines as well as DCTPP1, which can degrade deoxynucleoside triphosphates. Moreover several DNA repair enzymes SAMHD1, MTH1 and TDP1 were increased. However, inhibition of MTH1 and DCTPP1 did not increase sensitivity to RX-3117. In conclusion, induction of resistance to the novel cytidine analog RX-3117 led to a decreased accumulation of RX-3117 ribonucleotides, which might be associated with an increased degradation. Citation Format: Godefridus J. Peters, Dzjemma Sarkisjan, Btissame El Hassouni, Richard J. Honeywell, Joris R. Julsing, Beatrice Balboni, Daniel J. De Klerk, Safet Zekanovic, Kees Smid, Elisa Giovannetti, Young B. Lee, Deog J. Kim. Unusual mechanism of resistance to the novel cytidine analog fluorocyclopentenylcytosine (RX-3117) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1267.

A novel cytidine analog fluorocyclopentenylcytosine (RX-3117; TV-1360) was characterized for its cytotoxicity in a 59-cell line panel and further characterized for cytotoxicity, metabolism and mechanism of action in 15 additional cancer cell lines, including gemcitabine-resistant variants. In both panels sensitivity varied 75-fold (IC50: 0.4- > 30 μM RX-3117). RX-3117 showed a different sensitivity profile compared to cyclopentenyl-cytosine (CPEC) and azacytidine, substrates for uridine-cytidine-kinase (UCK). Dipyridamole, an inhibitor of the equilibrative-nucleoside-transporter protected against RX-3117. Uridine and cytidine protected against RX-3117, but deoxycytidine (substrate for deoxycytidine-kinase [dCK]) not, although it protected against gemcitabine, demonstrating that RX-3117 is a substrate for UCK and not for dCK. UCK activity was abundant in all cell lines, including the gemcitabine-resistant variants. RX-3117 was a very poor substrate for cytidine deaminase (66,000-fold less than gemcitabine). RX-3117 was rapidly metabolised to its nucleotides predominantly the triphosphate, which was highest in the most sensitive cells (U937, A2780) and lowest in the least sensitive (CCRF-CEM). RX-3117 did not significantly affect cytidine and uridine nucleotide pools. Incorporation of RX-3117 into RNA and DNA was higher in sensitive A2780 and low in insensitive SW1573 cells. In sensitive U937 cells 1 μM RX-3117 resulted in 90 % inhibition of RNA synthesis but 100 μM RX-3117 was required in A2780 and CCRF-CEM cells. RX-3117 at IC50 values did not affect the integrity of RNA. DNA synthesis was completely inhibited in sensitive U937 cells at 1 μM, but in other cells even higher concentrations only resulted in a partial inhibition. At IC50 values RX-3117 downregulated the expression of DNA methyltransferase. In conclusion, RX-3117 showed a completely different sensitivity profile compared to gemcitabine and CPEC, its uptake is transporter dependent and is activated by UCK. RX-3117 is incorporated into RNA and DNA, did not affect RNA integrity, depleted DNA methyltransferase and inhibited RNA and DNA synthesis. Nucleotide formation is related with sensitivity.

Fluorocyclopentenylcytosine (RX-3117) is an orally available cytidine analog, currently in Phase I clinical trial. RX-3117 has promising antitumor activity in various human tumor xenografts including gemcitabine resistant tumors. RX-3117 is activated by uridine-cytidine kinase (UCK). Since UCK exists in two forms, UCK1 and UCK2, we investigated which form is responsible for RX-3117 phosphorylation. For that purpose we transfected A549 and SW1573 cell lines with UCK-siRNAs. Transfection of UCK1-siRNA efficiently downregulated UCK1-mRNA, but not UCK2-mRNA expression, and did not affect sensitivity to RX-3117. However, transfection of UCK2-siRNA completely downregulated UCK2-mRNA and protein and protected both A549 and SW1573 against RX-3117. UCK enzyme activity in two panels of tumor cell lines and xenograft cells correlated only with UCK2-mRNA expression (r = 0.803 and 0.915, respectively), but not with UCK1-mRNA. Moreover, accumulation of RX-3117 nucleotides correlated with UCK2 expression. In conclusion, RX-3117 is activated by UCK2 which may be used to select patients potentially sensitive to RX-3117.

Clavulanic acid is a psychoactive compound that has been shown to modulate central nervous system activity. Importantly, in neurotoxin-induced animal models, clavulanic acid has been shown to improve motor function (Huh et al., 2010) suggesting that it can be neuroprotective; however, the mechanism as how clavulanic acid can induce neuroprotection is not known. We demonstrate here that clavulanic acid abrogates the effects of the neurotoxin 1-methyl-4-phenylpyridinium (MPP(+)) which mimics Parkinson's disease (PD) by inducing neurodegeneration. To further establish the mechanism we identified that clavulanic acid inhibits neurotoxin-induced loss of mitochondrial membrane potential and ROS production. Consistent with these results, neurotoxin-induced increase in Bax levels was also decreased in clavulanic acid treated cells. Importantly, neurotoxin-induced release of cytochrome c levels as well as caspase activation was also inhibited in clavulanic acid treated cells. In addition, Bcl-xl levels were also restored and the Bcl-xl/Bax ratio that is critical for inducing apoptosis was increased in clavulanic acid treated cells. Overall, these results suggest that clavulanic acid is intimately involved in inhibiting neurotoxin-induced loss of mitochondrial function and induction of apoptosis that contributes towards neuronal survival.

Human norepinephrine (NE) deficiency (or dopamine β-hydroxylase (DBH) deficiency) is a rare congenital disorder of primary autonomic failure, in which neurotransmitters NE and epinephrine are undetectable. Although potential pathogenic mutations, such as a common splice donor site mutation (IVS1+2T→C) and various missense mutations, in NE deficiency patients were identified, molecular mechanisms underlying this disease remain unknown. Here, we show that the IVS1+2T→C mutation results in a non-detectable level of DBH protein production and that all three missense mutations tested lead to the DBH protein being trapped in the endoplasmic reticulum (ER). Supporting the view that mutant DBH induces an ER stress response, exogenous expression of mutant DBH dramatically induced expression of BiP, a master ER chaperone. Furthermore, we found that a pharmacological chaperone, glycerol, significantly rescued defective trafficking of mutant DBH proteins. Taken together, we propose that NE deficiency is caused by the combined abnormal processing of DBH mRNA and defective protein trafficking and that this disease could be treated by a pharmacological chaperone(s).

RX-3117 is a novel, investigational, oral, small molecule nucleoside compound that shows promising antitumor activity in xenografts including patient-derived xenografts resistant to gemcitabine. RX-3117 is currently being evaluated in a Phase IIa multi-center, open-label clinical study in patients with relapsed or refractory pancreatic cancer and advanced bladder cancer. RX-3117 can downregulate DNMT1 and activate genes controlled by methylation, such as E-cadherin and p16. We aimed to elucidate the mechanism of RX-3117 mediated downregulation of DNMT1. Expression of DNMT1 was evaluated by western blotting. Binding of DNMT1 to DNA was measured after DNA isolation, DNAse treatment and gel electrophoresis. DNMT1 trapping in the nucleus was also studied with ImageStream FACS analysis. DNMT1 ubiquitination was measured by immunoprecipitation and quantification of the ubiquitin tag K48. Translocation of DNMT1 was studied by confocal microscopy. Modeling studies were performed with Quantum Mechanics (QM) and Molecular Dynamics (MD). DNMT1 acts on the DNA during the so-called base flipping necessary for methyl transfer. To determine whether RX-3117 treatment would lead to trapping of DNMT1, NSCLC A549 and PDAC SUIT-028 cells were treated for 24 hr with 1 µM RX-3117. Immunostaining of DNMT1-DNA and ImageStream FACS analysis demonstrated binding of DNMT1 to DNA. Treatment with RX-3117 also resulted in DNMT1 ubiquitination, as shown by an increase in the ubiquitin tag K48, reaching the highest level after 48 hr. Incubation of A549 and SUIT-028 cells with 80 nM of the specific proteasome inhibitor bortezomib prevented RX-3117 mediated degradation of DNMT1 (at 24 and 24 hr exposure to 1 µM RX-3117). This underlines the role of the proteasome in DNMT1 degradation. With confocal microscopy it was demonstrated that DNMT1 and the proteasome co-localized and translocated to the cytosol of A549 and SUIT-028 cells treated for 48 hours with 1 µM RX-3117. With molecular modelling using QM and MD, changes in nucleophilicity of C4-C5 double bound were observed indicating that DNMT1 would initiate methyl transfer but cannot proceed. In summary we conclude that RX-3117 induces epigenetic changes in cancer cells by trapping DNMT1 in the nucleus followed by translocation of the protein to the proteasome for degradation. Citation Format: Dzjemma Sarkisjan, Ferry Pronk, Rosan Kuin, Btissame el Hassouni, Young B. Lee, Deog J. Kim, Marc Dijk, Daan P. Geerke, G. J. Peters. RX-3117 promotes epigenetic effects in cancer cells through enhanced degradation of DNMT1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5861.

Clavulanic acid is a psychoactive compound with excellent blood-brain barrier permeability and safety profiles. Previous studies showed that clavulanic acid suppresses anxiety in rodents and in a primate model. In addition, clavulanic acid is thought to enhance sexual function in animal models via central nervous system (CNS) mechanisms. To further examine its potential as a CNS-modulating agent, we investigated the effects of clavulanic acid in neurotoxin-induced animal models that emulate neurodegenerative disease symptoms. Clavulanic acid was administered to rodents that were exposed to kainic acid or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Using histochemical staining of brain sections, we demonstrated that clavulanic acid protects hippocampal and dopaminergic neurons from toxin-induced acute death. We also observed that clavulanic acid improves motor function in MPTP-treated mice in a behavioral test. These data indicate that clavulanic acid may have neuroprotective effects and warrants further investigation of its therapeutic use in CNS disorders, such as Parkinson's and Alzheimer's disease. Drug Dev Res 71:351–357, 2010. © 2010 Wiley-Liss, Inc.

Sexual behaviour in rats can be used to predict putative effects on human sexual behaviour. Anecdotic reports exist, that the beta-lactamase inhibitor, clavulanic acid exerts sexual stimulating activities in monkeys. To characterize these pro-sexual activities, clavulanic acid was tested in three doses and compared to one dose of a sexually inhibitory dose of the selective serotonin reuptake inhibitor, paroxetine, in sexually-experienced male rats, selected for a moderate level of sexual performance in a standard 30-min test with an oestrus female. After acute administration, clavulanic acid had minor sexual stimulating effects at the highest dose in the number of intromissions and in the first ejaculation series. After sub-chronic 7-days treatment, clavulanic acid increased the number of ejaculations at all three doses and reduced the number of intromissions in the 1st series at the highest dose. After chronic 14 days treatment, a similar but stronger pro-sexual profile was observed. The sexual side effects of paroxetine were as expected, including slight sexual inhibitory effects after acute administration, but somewhat stronger overall inhibitory effects after 7 and 14-days pretreatment, particularly notable in the decreasing number of animals contributing to the 2nd ejaculation series, which was even stronger after 14-days treatment. One week after cessation of treatment, the paroxetine group had completely recovered, whereas the highest dose-group of clavulanic acid still showed some pro-sexual effects. This remarkable pro-sexual activity of clavulanic acid cannot readily be explained by its mechanism of action as a beta-lactamase inhibitor but could be due to unexpected central activity of the compound.

SummaryMouse factor X was highly purified from plasma using barium ion precipitation and chromatography on anion-exchange and heparin- agarose affinity chromatography columns. Intact and reduced patterns of mouse factor X in SDS-PAGE were similar to those of human factor X. The specific absorption E 1%/1 cm at 280 nm of mouse factor X was found to be 11.2. Content of carbohydrate moieties of mouse factor X, determined to be 10% by weight, differs both quantitatively and quantitatively from that of human factor X, while the γ-carboxy- glutamic acid (Gla) and β-hydroxy-aspartic acid (β-OH-Asp) content were essentially the same as for human factor X. The amino-terminal amino acid sequences of the light and heavy chains of mouse factor X separated by SDS-PAGE were ANSFF--FKK and SVALXTSDSE, respectively. Underlined residues are non-identical with those of human factor X. Clotting time-based assays using human factor X- deficient plasma as substrate exhibited the following apparent extents of activation of factor X in mouse plasma, using human plasma as the standard: 195% (intrinsic); 200% (extrinsic); and 190% (RVV-X). Using the purified proteins in the same assay systems, the following apparent activation of mouse factor X was demonstrated, compared with human factor X: 195% (intrinsic); 27% (extrinsic); and 41% (RVV-X). These activity profiles suggest that the human extrinsic coagulation pathway functions less efficiently than the corresponding mouse pathway in the activation of mouse factor X. Furthermore, mouse brain thromboplastin satisfactorily replaced rabbit brain thromboplastin in extrinsic activation of factor X in mouse plasma, but not of human plasma or purified mouse or human factor X, in line with studies by others suggesting that human factor Vila poorly activates factor X in the presence of mouse tissue factor. While fully RVV-X-activated mouse factor X activated human prothrombin at a rate equal to about 117% of that for human factor X, it hydrolyzed the synthetic substrate, S-2222, at a rate of only about 18% of that for human factor X. These results are expected to be useful in making the mouse suitable for study of the mammalian blood coagulation pathways.

SummaryNaturally occurring plasma factor XFriuli (pFXFr) is marginally activated by both the extrinsic and intrinsic coagulation pathways and has impaired catalytic potential. These studies were initiated to obtain confirmation that this molecule is multi-functionally defective due to the substitution of Ser for Pro at position 343 in the catalytic domain. By the Nelson-Long site-directed mutagenesis procedure a construct of cDNA in pRc/CMV was derived for recombinant factor XFriuli (rFXFr) produced in human embryonic (293) kidney cells. The rFXFr was purified and shown to have a molecular size identical to that of normal plasma factor X (pFX) by gel electrophoretic, and amino-terminal sequencing revealed normal processing cleavages. Using recombinant normal plasma factor X (rFXN) as a reference, the post-translational y-carboxy-glutamic acid (Gla) and (β-hydroxy aspartic acid (β-OH-Asp) content of rFXFr was over 85% and close to 100%, respectively, of expected levels. The specific activities of rFXFr in activation and catalytic assays were the same as those of pFXFr. Molecular modeling suggested the involvement of a new H-bond between the side-chains of Ser-343 and Thr-318 as they occur in anti-parallel (3-pleated sheets near the substrate-binding pocket of pFXFr. These results support the conclusion that the observed mutation in pFXFr is responsible for its dysfunctional activation and catalytic potentials, and that it accounts for the moderate bleeding tendency in the homozygous individuals who possess this variant procoagulant.

Variant factor X in an individual with a mild bleeding tendency was suspected based on deficient procoagulant activity (10–20% of normal) and antigen (30–35% of normal) levels of plasma factor X. Heteroduplex analysis of factor X gene exons indicated heterozygosity for mutations in both exons 6 and 4, confirmed by direct sequencing of the amplified exons. Substitution of C by T at nucleotide position 13 984 (Arg-139 to Cys) was found in the factor X gene exon 6 of the propositus. This mutation creates a BsmI site and the patient tested heterozygous for the BsmI cleavage involved, as did one of his two daughters. In addition, exon 4 was found to have the normal A and a novel C (Asn-57 to Thr) at nucleotide position 9338. The exon 4 mutation creates a BsaJI site, detectable after amplification mismatch to remove an existing BsaJI site. Both the patient and the second of his two daughters were heterozygous for this cleavage. The two variant proteins are called factors XWenatchee I (Arg-139 to Cys) and II (Asn-57 to Thr). A mixed variant isolate derived from the plasma of the propositus exhibited heavy/light chains of normal size, as well as an apparent single-chain molecule not dissociable by reducing agent. A single-chain molecule would be predicted for form I, if the mutation blocks processing cleavages that normally remove a tripeptide interposed between the heavy and light chains. A Western blot of partially purified factor X from the daughter who inherited the form I defect revealed a component migrating the same as the putative single-chain species. Based upon the factor X activity vs. antigen ratios for the propositus and both daughters, both forms I and II are probably dysfunctional molecules.

RX-3117 (Fluorocyclopentenylcytosine; FCPEC) is an orally bioavailable novel cytidine analog which is currently being evaluated in a Phase I clinical study. Downregulation of DNA methyltransferase 1 (DNMT1) by RX-3117 was shown in various cell lines with different histological backgrounds. In the present study we determined the effect of RX-3117 on DNMT1 at the DNA, RNA, protein and enzyme activity, and reactivation of suppressed target genes, including p16INK4A, methylguanine methyltransferase (MGMT) and the proton coupled folate transporter (PCFT). In the moderately sensitive non-small cell lung cancer (NSCLC) cell lines such as A549 and SW1573, 5-50 μM RX-3117 downregulated DNMT1 protein expression by 5-20% after 24 hr exposure and >90% after 48 hr. DNMT1 mRNA was not affected after 24 hr exposure but was affected moderately after 48 hr. In the sensitive ovarian cancer cell line A2780, protein down regulation was already observed after 24 hr at 1 μM RX-3117. DNMT1 activity was inhibited by 1 μM RX-3117 by 32% which was similar to the percent inhibition with 5 μM of the reference compound 5-aza-2’-deoxycytidine (DAC, 31%). In A549 cells 5 μM RX-3117 decreased overall methylation of DNA (detected by an antibody against 5-methylcytosine) by 25% after 48 hr exposure, while 5 μM DAC only inhibited 9%. For several genes known to be affected by methylation, we evaluated their protein expression and activity. In A549 and SW1573 cells a 24 hr exposure to 5 μM RX-3117 increased the expression of the cell cycle protein p16INK4A and of the DNA repair enzyme MGMT. For PCFT we evaluated its functional activity in CCRF-CEM leukemic cells which have a highly methylated PCFT promoter and in CEM-MTX cells which are deficient for the reduced folate carrier (RFC). PCFT is a specific folate transporter responsible for uptake of folic acid and the folate analogs methotrexate (MTX) and pemetrexed. Incubation of both CEM and CEM-MTX cells with either 29.6 μM RX-3117 or DAC as a positive control markedly increased PCFT mediated transport of MTX. This was more pronounced in CEM-MTX cells, 10-11-fold increase for both RX-3117 and DAC, compared to a 4-fold increase in CEM cells. In conclusion, the down-regulation of DNMT1 by RX-3117 was accompanied by a decrease in DNMT1 protein expression and enzyme activity, resulting in up-regulation of proteins of MGMT, PCFT, and the tumor suppressor gene p16INK4A. These data underline DNMT1 inhibition as a novel mechanism of RX-3117. Citation Format: Godefridus J. Peters, Dzjemma Sarkisjan, Joris J. Julsing, Ahmed Hassan, Kees Smid, Ietje Kathmann, Young Lee, Deog J. Kim. Inhibition of DNA methyltransferase by RX-3117 (fluorocyclopentenylcytosine) leads to upregulation of hypomethylated targets. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4725.

238 Background: DEAD box RNA helicase DDX5/p68, and its phosphorylated form in particular, may play several important roles in cancer by means of cell transformation, epithelial mesenchymal transition (EMT), and cell migration, deeming it a promising target for novel anti-cancer therapeutics. We have previously shown that Supinoxin (RX-5902) interacts with phosphorylated p68 on Tyr593, interfering with the phosphorylated p68-β-catenin signaling pathway. Supinoxin also inhibits motility of MDA-MB231 breast cancer cell lines and could potentially prevent metastasis in cancer. Methods: In this study, we first demonstrated anti-proliferative effects in several cell lines originated from pancreas (5 cell lines) with a high level of sensitivity to Supinoxin (IC50 of 18 nM). We also sought to examine the tumor growth inhibition (TGI) and/or tumor growth delay (TGD), and survival benefits of Supinoxin in the human pancreatic carcinoma (MiaPaCa-2) xenograft mouse model. Results: In the MiaPaCa-2 model, at 50 and 70 mg/kg daily (oral, 5 days on/2 days off) for 3 weeks, both doses delayed tumor growth significantly (83% and 339%; P < 0.001). All animals in the high dose showed complete regression (CR) and completing the study as tumor free survival (TFS; Day 65); one animal showed CR and TFS in the lower dose. Gemcitabine (120 mg/kg ip; Q3D for 4 weeks) resulted in TGD of 71% (P < 0.001), with no CRs. Supinoxin did not result in a reduction in body weight gain, treatment related deaths, or clinical observations in this tumor model. Conclusions: These data support the potential therapeutic activity of Supinoxin in pancreatic cancer. A Phase 1 study of Supinoxin on relapse/refractory solid tumors is ongoing (NCT02003092).

524 Background: DEAD box RNA helicase DDX5/p68 may play several important roles in cancer. In particular, phosphorylated p68 has been shown to be associated with cell transformation, epithelial mesenchymal transition (EMT), and cell migration, deeming it a promising target for novel anti-cancer therapeutics. We have previously shown that Supinoxin (RX-5902) interacts with phosphorylated p68 on Tyr593, interfering with the phosphorylated p68-β-catenin signaling pathway. Methods: In this study, we first demonstrated anti-proliferative effects in ten renal cancer cell lines with a high level of sensitivity to Supinoxin (IC50 of 39 nM); TK-10 was the only resistant cell line in this study. We also sought to examine the tumor growth inhibition (TGI), tumor growth delay (TGD), and survival benefits of Supinoxin in the human renal cell carcinoma tumor (Caki-1) xenograft mouse model, using two different dosing schemas: weekly dosing at 20-160 mg/kg for 4 weeks, or 50-70 mg/kg daily (5 days on/2 days off) for 3 weeks. Results: Weekly dosing of Supinoxin at 160 mg/kg resulted in a 75% TGD (P < 0.001). Daily administration of Supinoxin resulted in dose-dependent TGI (80 and 96%; Day 21) and TGD (68 and 104%, P < 0.001), and extended the overall survival of the animals at both doses (P < 0.0001). At the dose of 70 mg/kg daily, 6/10 animals demonstrated partial tumor regressions and 1/10 a complete tumor regressions. Supinoxin did not result in a reduction in body weight gain, treatment related deaths, or clinical observations in either of the dosing schemas. Sunitinib (60 mg/kg; daily for 21 days) resulted in TGD for both in vivo studies validating the Caki-1 model herein. Conclusions: These data support the potential therapeutic activity of Supinoxin in renal cell cancers. A Phase I study of Supinoxin on relapse/refractory solid tumors is ongoing (NCT02003092).

Human embryonic kidney cells (293) were transfected with a construct containing human factor X cDNA and selected for G418 resistance. The level of expression of recombinant factor X in serum-free medium was 4 to 5 μg/ml. Purified recombinant factor X had a molecular size identical to that of normal plasma factor X. Amino-terminal sequencing revealed normal processing cleavages. The γ-carboxy Glu and β-OH Asp content of the recombinant factor X was close to 90% of the expected levels of these post-translational residues. The specific activity of recombinant factor X was about 95% of that of plasma factor X in three plasma-based clotting assays. This report demonstrates that 293 cells can produce a high level of biologically active factor X and describes a visual criterion for verifying the transfection process.

Clavulanic acid is a CNS-modulating compound with exceptional blood-brain barrier permeability and safety profile. Clavulanic acid has been proposed to have anti-depressant activity and is currently entering Phase IIb clinical trials for the treatment of Major Depressive Disorder (MDD). Studies have also shown that clavulanic acid suppresses anxiety and enhances sexual functions in rodent and primate models by a mechanism involving central nervous system (CNS) modulation, although its detailed mechanism of action has yet to be elucidated. To further examine its potential as a CNS modulating agent as well as its mechanism of action, we investigated the effects of clavulanic acid in neuronal cells. Our results indicate that clavulanic acid enhances dopamine release in PC12 and SH-SY5Y cells without affecting dopamine synthesis. Furthermore, using affinity chromatography we were able to identify two proteins, Munc18-1 and Rab4 that potentially bind to clavulanic acid and play a critical role in neurosecretion and the vesicle trafficking process. Consistent with this result, an increase in the translocation of Munc18-1 and Rab4 from the cytoplasm to the plasma membrane was observed in clavulanic acid treated cells. Overall, these data suggest that clavulanic acid enhances dopamine release in a mechanism involving Munc18-1 and Rab4 modulation and warrants further investigation of its therapeutic use in CNS disorders, such as depression.

A mixed culture of bacteria capable of growth on cyanide was isolated from an activated sludge of coal tar wastewater by an enrichment culture technique. The predominant cyanide-degrading microorganisms found in this bacterial mixture were identified as species of the genera Klebsiella, Serratia, Moraxella, and Pseudomonas. Stoichiometric amounts of ammonia were released during the cyanide containing culture by microbial oxidation of cyanide.

The AKT pathway is an important therapeutic target for cancer drug discovery as it functions as a main point for transducing extracellular and intracellular oncogenic signals. Moreover, alternations of the AKT pathway have been found in a wide range of cancers. In the present study, we found that an Akt1 antisense oligonucleotide (Akt1 AO) significantly downregulated the expression of AKT1 at both the mRNA and protein levels and inhibited cellular growth at nanomolar concentrations in various types of human cancer cells. Combined treatment of Akt1 AO with several cytotoxic drugs resulted in an additive growth inhibition of Caki-1 cells. The in vivo effectiveness of Akt1 AO was determined using two different xenograft nude mouse models. Akt1 AO (30 mg/kg, i.v. every 48 h) significantly inhibited the tumor growth of nude mouse subcutaneously implanted with U251 human glioblastoma cells after 27 days treatment. Akt1 AO (30 mg/kg, i.p continuously via osmotic pump) also significantly inhibited the tumor formation in nude mice implanted with luciferase-expressing MIA human pancreatic cancer cells (MIA-Luc) after 14 days of treatment. The luciferase signals from MIA-Luc cells were reduced or completely abolished after 2 weeks of treatment and the implanted tumors were barely detectable. Our findings suggest that Akt1 AO alone or in combination with other clinically approved anticancer agents should be further explored and progressed into clinical studies as a potential novel therapeutic agent.

To seek the possible molecular defect in a patient with deficient factor X plasma procoagulant activity, factor X gene exosn and splice junctions were subjected to heteroduplex analyses and sequencing. A mutation in exon 2 was confirmed as substitution of A by G at nucleotide position 206, coding for Gly instead of a Glu which is a normal precursor for gamma-carboxylated glutamic acid (Gla) at amino acid position 14. An abolished TaqI restriction site was used to indicate homozygosity of the defect, but occurrence of a gene deletion with attendant heterozygosity could not be excluded. The deletion of a Gla residue could affect the Ca(2+)-binding properties of factor X or confer a flexibility interfering with the interactive properties of the light chain. The defect could explain the decreased functional activity of circulating factor X and the mild bleeding tendency of the propositus.

Cytidine analogs play an important role in the treatment of various types of cancer, both solid tumors and leukemia. A novel cytidine analog fluorocyclopentenylcytosine (RX-3117) was characterized for its cytotoxic effects, its metabolism and its mechanism of action in a panel of 9 solid tumor and leukemic cell lines, as well as 6 variants resistant to gemcitabine, cytarabine and other pyrimidine analogs. Sensitivity in the parent cell lines after 72 hr exposure varied 75 fold with IC50 values from 0.4 to 30 µM RX-3117. The human equilibrative nucleoside transporter mediates transport of RX-3117, since its inhibition protected cells. Uridine and cytidine also protected cells against RX-3117, indicating that activation of RX-3117 is dependent on phosphorylation catalyzed by uridine-cytidine kinase (UCK), which was abundant in all tested cell lines, including the gemcitabine resistant variants. Deoxycytidine did not protect cells against RX-3117. RX-3117 was a very poor substrate for cytidine deaminase (66,000-fold less than gemcitabine). After its uptake in cells, RX-3117 was rapidly metabolised to its nucleotides with the triphosphate being the most prominent form (90% of all nucleotides), while synthesis of the nucleotides was highest in the most sensitive cell lines (U937 and A2780 cells) and lowest in the least sensitive cells (CCRF CEM cells). No difference in nucleotide formation was observed between the SW1573 and its gemcitabine resistant variant SW1573/G. In the AG6000 cells, the dCK- variant of A2780 and resistant to gemcitabine and RX-3117, a normal monophosphate level was found, but no di-and triphosphates were formed, explaining its resistance. Similarly incorporation of RX-3117 into RNA and DNA was higher in the sensitive A2780 and low in the insensitive SW1573 cells, with no difference between the gemcitabine sensitive and resistant variants. The effect of RX-3117 on synthesis of RNA and DNA was quite different; in the sensitive U937 cells 10 µM RX-3117 inhibited RNA synthesis 90%, while in A2780 and CCRF-CEM cells 100 µM RX-3117 was required for 90% inhibition of RNA synthesis. The effect on DNA synthesis was quite different. 1 µM RX-3117 completely inhibited DNA synthesis in the sensitive U937 cells, 80-90% inhibition was achieved with 10 µM in both CCRF CEM variants and with 100 µM in SW1573/G and AG6000, but in A2780 and SW1573 cells 100 µM only resulted in a partial or no inhibition, respectively. In conclusion, RX-3117 showed a completely different sensitivity profile compared to other cytidine analogs. Its uptake is transporter dependent; it is not activated by dCK, but by UCK. RX-3117 is incorporated into RNA and DNA; RX-3117 hardly affected RNA synthesis at IC50 values, but inhibited DNA synthesis. Its metabolism to nucleotides is related with its sensitivity, possibly because they directly inhibit the target presumably DNA methyltransferase. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1770. doi:1538-7445.AM2012-1770

A series of isoquinolineamine small molecule derivatives were synthesized and screened as potential anticancer agents. Among them, we identified one isoquinolineamine analogue with potential anticancer activity. This compound inhibited the proliferation of a variety of cancer cells derived from many human solid tumors with IC50 values ranging from 14 nM to 71 nM. The compound also was more effective against gemcitabine and cisplatin-resistant cancer cell lines when compared to the original cytotoxic cancer drugs. In mice bearing tumor xenografts, treatment with the compound significantly inhibited the growth of tumors, enhanced tumor regression, and also prevented the growth of tumors in a paclitaxel-resistant xenograft model. This compound is well tolerated and had no effects on body weight compared to control animals. Mechanistic studies showed that cancer cells treated with this compound resulted in the elevation of cytochrome c in the cytosol, the decrease of Bcl-2 and the activation of Caspase 9. Further studies showed inhibition of the expression of several signaling molecules important for cell proliferation (p-Erk, p-p38 and p-Akt) and also decreased protein levels of p-GSK3α/β and β-catenin. Therefore, our result suggests that this compound could be a promising antitumor agent. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3562.