Transport characteristics of a novel local drug delivery system using nordihydroguaiaretic acid (NDGA)-polymerized collagen fibers

The use of nordihydroguaiaretic acid (NDGA)-polymerized collagen fibers as a novel local drug delivery system is introduced. The drug loading of these biocompatible fibers is illustrated with the anti-inflammatory agents dexamethasone and dexamethasone 21-phosphate. Capillary zone electrophoresis was used to measure the amount of drug released from the fibers into phosphate buffered saline with time. From these measurements and the use of a mathematical model, we were able to determine the diffusion coefficients for dexamethasone (D = 1.86 x 10(-14) m2/s) and dexamethasone 21-phosphate (D = 2.36 x 10(-13) m2/s) in the NDGA collagen fibers. These values have not been previously reported. These fibers can be used to load other agents as well. The diffusion coefficient of any agent loaded in these fibers can be determined using the techniques and mathematical method described. The rate of drug release from the fibers can be controlled using a PLGA coating. The overall importance of this paper is the potential broad application of this novel drug delivery system for the treatment of various human diseases.     

IGF-1R tyrosine kinase expression and dependency in clones of IGF-1R knockout cells (R-)

Insulin-like growth factor 1 receptor (IGF-1R) plays many crucial roles in cancer, like anti-apoptotic activity and necessity for transformation. IGF-1R knockout cells (R-) represent a useful tool for molecular mapping of biological properties of the receptor. R- cells have been shown to be refractory to transformation by viral and cellular oncogenes, highlighting the necessity of this receptor for transformation. Surprisingly, more recent studies have shown that these cells can undergo spontaneous transformation. This observation raises the question as whether R- cells over the years have acquired some properties mimicking those of IGF-1R. Using an IGF-1R inhibitor (cyclolignan PPP) we have identified clones of R- (R-s) that are sensitive to this compound. Since, PPP is closely related to podophyllotoxin, which is an efficient microtubule inhibitor, we first investigated if such a mechanism could explain the sensitivity to PPP. However, highly purified PPP showed no or very slight tubulin binding. Further analysis of R-s revealed expression of a 90 kDa protein being reactive to IGF-1R beta-subunit antibodies. This protein was weakly but constitutively tyrosine phosphorylated and was downregulated by siRNA targeting IGF-1R. This downregulation was paralleled by decreased R-s survival. Taken together, our study suggests that clones of R- express IGF-1R activity and dependency, which in turn may explain that R- can undergo spontaneous transformation.     

Inhibition of soybean lipoxygenase 1 by N-alkylhydroxylamines

Micromolar concentrations of N-octylhydroxylamine dramatically increase the induction period in the conversion of linoleic acid to 13(S)-hydroperoxy-cis-9,trans-11-octadecadienoic acid (13-HPOD) catalyzed by soybean lipoxygenase 1. The induction period produced by N-octylhydroxylamine is abolished by 13-HPOD but not by the corresponding hydroxy acid. Addition of a catalytic amount of lipoxygenase to a mixture of 13-HPOD and N-octylhydroxylamine results in consumption of approximately 1 mumol of 13-HPOD/mumol of N-octylhydroxylamine present. These results can be explained by a model in which 13-HPOD oxidizes the enzyme from an inactive ferrous form to an active ferric form, as proposed by previous workers, and N-octylhydroxylamine reduces the enzyme back to the ferrous form. Consistent with this model, the ESR signal at g = 6.1 characteristic of ferric lipoxygenase is rapidly abolished by N-octylhydroxylamine and can be regenerated by 13-HPOD. These results provide additional support for earlier proposals that ferric lipoxygenase is the catalytically active form and also establish a novel method of inhibiting enzymes in this class. The octyl group of N-octylhydroxylamine appears to contribute to binding near the iron, since hydroxylamine and N-methylhydroxylamine do not extend the induction period. In the n-RNHOH series, activity passes through an optimum at R = decyl.     

Synthesis,characterization, and anti-melanoma activity of tetra-O-substituted analogs of nordihydroguaiaretic acid

Synthesis of seven semi-synthetic analogs of NDGA is described. An approach to NDGA derivatization is described in which the ortho-phenolic groups are tethered together by one atom, forming a 5-membered heterocyclic ring. The analogs were evaluated for cytotoxicity in four cancer cell lines and compared to NDGA and tetra-O-methyl-NDGA (M4N) (1a). NDGA bis-cyclic sulfate (2a), NDGA bis-cyclic carbonate (2b), and methylenedioxyphenyl-NDGA (2d) and NDGA tetra acetate (1b) showed anti-cancer activity in vitro. Two compounds, (1b) and (2b), were evaluated for anticancer activity in a mouse xenograft model of human melanoma and showed dose-dependent activity.     

Inhibition of bacterial peptide deformylase by biaryl acid analogs

Peptide deformylase is an essential eubacterial metalloenzyme involved in the maturation of proteins by cleaving the N-formyl group from N-blocked methionine polypeptides. Biaryl acid analogs containing tetrazole, acyl sulfonamide, or carboxylate pharmacophores were found to be potent inhibitors of recombinant Escherichia coli peptide deformylase. Two of these compounds, a biphenyl tetrazole, compound 1, and a biphenyl acyl sulfonamide, compound 4, were competitive inhibitors with K(i) values of 1.2 and 6.0 microM, respectively. By analogy to the binding of related compounds to other metalloenzymes such as Bacteroides fragilis metallo-beta-lactamase CcrA and human carbonic anhydrase, a mechanism of inhibition is proposed for these peptide deformylase inhibitors where the acidic moieties form direct ionic interactions with the active site metal cation.     

IGF-1及IGF-1R在胃癌中的表达及意义

目的探讨胰岛素样生长因子1(insulin-like growth factor-1,IGF-1)及胰岛素样生长因子1受体(insulin-like growth factor-1receptor,IGF-1R)在胃癌及癌旁胃黏膜组织中的表达及意义。方法采用免疫组化MaxVision两步法检测80例胃癌和50例癌旁胃黏膜组织中IGF-1及IGF-1R蛋白的表达,并分析两者与胃癌患者临床病理指标间的关系及其相关性。结果 IGF-1及IGF-1R蛋白在胃癌组织中表达阳性率分别为71.25%和75.00%,在癌旁胃黏膜组织中表达阳性率分别为30.00%和24.00%,差异有统计学意义(Z=-4.942,P0.001;Z=-5.688,P0.001)。IGF-1及IGF-1R蛋白的表达与胃癌的组织分化程度、有无淋巴结转移、浸润深度及临床分期相关(Z=-2.067、-2.837,P0.05;Z=-4.117、-3.579,P0.05;Z=-2.885、-2.836,P0.05;Z=-3.286、-3.313,P0.05)。相关性分析显示两者表达呈正相关。结论 IGF-1和IGF-1R蛋白在胃癌组织中呈高表达,两者可能在胃癌的发生、发展过程中具有协同及相互调节的作用。IGF-1和IGF-1R蛋白可能成为胃癌早期诊断、评估胃癌患者预后的重要指标。     

Inhibition of class C beta-lactamases by (1''R,6R)-6-(1''-hydroxy)benzylpenicillanic acid SS-dioxide.

beta-Lactamases, enzymes that catalyse the hydrolysis of the beta-lactam ring in beta-lactam antibiotics, are divided into three classes, A, B and C, on the basis of the structures so far determined. There are relatively few effective inhibitors of class C beta-lactamases. A beta-lactam sulphone with a hydroxybenzyl side chain, namely (1'R,6R)-6-(1'-hydroxy)benzylpenicillanic acid SS-dioxide (I), has now been studied. The sulphone is a good mechanism-based inhibitor of class C beta-lactamases. At pH8, the inhibition of a Pseudomonas beta-lactamase is irreversible, and proceeds at a rate that is about one-tenth the rate of concurrent hydrolysis. The labelled enzyme has enhanced u.v. absorption and is probably an enamine. At a lower pH, however, inhibition is transitory.     

Inhibition of rabbit neutrophil lysosomal enzyme secretion,non-stimulated and chemotactic factor stimulated locomotion by nordihydroguaiaretic acid

Nordihydroguaiaretic acid irreversibly inhibits both Ca⁺⁺ dependent and independent lysosomal enzyme release from rabbit peritoneal neutrophils induced by the chemotactic factors, formyl-methionyl-leucyl-phenylalanine and C5a in the presence of cytochalasin B. The inhibition is both concentration and time dependent. In addition, the cytochalasin B dependent release induced by arachidonic acid and the Ca⁺⁺ ionophore A23187 is similarly inhibited. Similar concentrations of NDGA also inhibit neutrophil locomotion and chemotactic factor enhanced locomotion, as measured using modified Boyden chambers. As nordihydroguaiaretic acid has been shown to be an inhibitor of lipoxygenase activity, it is possible that this pathway of arachidonic acid metabolism is important in neutrophil locomotion and in cytochalasin B dependent lysosomal enzyme release induced by secretagogues.     

Inhibition of quinolinate phosphoribosyl transferase by pyridine analogs of quinolinic acid

The enzyme quinolinate phosphoribosyl transferase was purified from ATCC strain 23269. An HPLC method was developed for the analysis of the product of the enzyme reaction, nicotinate mononucleotide. Steady state kinetics in the forward reaction demonstrated a sequential mechanism for the enzyme. In order to gain more information on the mechanism of the enzyme reaction, a series of 2 substituted nicotinic acids and 2 substituted 3-nitropyridines were investigated as inhibitors of the reaction. The results indicate that potent inhibition results when the quinolinic acid analogs possessed a negatively charged group at the 2 position of the pyridine ring.     

High Expression Levels of Total IGF-1R and Sensitivity of NSCLC Cells In Vitro to an Anti-IGF-1R Antibody (R1507)

Background

The IGF receptor type 1 (IGF-1R) pathway is frequently deregulated in human tumors and has become a target of interest for anti-cancer therapy.

Methodology/Principal Findings

We used a panel of 22 non-small cell lung cancer (NSCLC) cell lines to investigate predictive biomarkers of response to R1507, a fully-humanized anti-IGF-1R monoclonal antibody (Ab; Roche). 5 lines were moderately sensitive (25–50% growth inhibition) to R1507 alone. While levels of phospho-IGF-1R did not correlate with drug sensitivity, 4 out of 5 sensitive lines displayed high levels of total IGF-1R versus 1 out of 17 resistant lines (p = 0.003, Fisher''s Exact). Sensitive lines also harbored higher copy numbers of IGF-1R as assessed by independent SNP array analysis. Addition of erlotinib or paclitaxel to R1507 led to further growth inhibition in sensitive but not resistant lines. In one EGFR mutant lung adenocarcinoma cell line (11–18), R1507 and erlotinib co-treatment induced apoptosis, whereas treatment with either drug alone induced only cell cycle arrest. Apoptosis was mediated, in part, by the survival-related AKT pathway. Additionally, immunohistochemical (IHC) staining of total IGF-1R with an anti-total IGF-1R Ab (G11;Ventana) was performed on tissue microarrays (TMAs) containing 270 independent NSCLC tumor samples. Staining intensity was scored on a scale of 0 to 3+. 39.3% of tumors showed medium to high IGF-1R IHC staining (scores of 2+ or 3+, respectively), while 16.7% had scores of 3+.

Conclusions/Significance

In NSCLC cell lines, high levels of total IGF-1R are associated with moderate sensitivity to R1507. These results suggest a possible enrichment strategy for clinical trials with anti-IGF-1R therapy.     

MiR-223 suppresses cell proliferation by targeting IGF-1R

To study the roles of microRNA-223 (miR-223) in regulation of cell growth, we established a miR-223 over-expression model in HeLa cells infected with miR-223 by Lentivirus pLL3.7 system. We observed in this model that miR-223 significantly suppressed the proliferation, growth rate, colony formation of HeLa cells in vitro, and in vivo tumorigenicity or tumor formation in nude mice. To investigate the mechanisms involved, we scanned and examined the potential and putative target molecules of miR-223 by informatics, quantitative PCR and Western blot, and found that insulin-like growth factor-1 receptor (IGF-1R) was the functional target of miR-223 inhibition of cell proliferation. Targeting IGF-1R by miR-223 was not only seen in HeLa cells, but also in leukemia and hepatoma cells. The downstream pathway, Akt/mTOR/p70S6K, to which the signal was mediated by IGF-1R, was inhibited as well. The relative luciferase activity of the reporter containing wild-type 3'UTR(3'untranslated region) of IGF-1R was significantly suppressed, but the mutant not. Silence of IGF-1R expression by vector-based short hairpin RNA resulted in the similar inhibition with miR-223. Contrarily, rescued IGF-1R expression in the cells that over-expressed miR-223, reversed the inhibition caused by miR-223 via introducing IGF-1R cDNA that didn't contain the 3'UTR. Meanwhile, we also noted that miR-223 targeted Rasa1, but the downstream molecules mediated by Rasa1 was neither targeted nor regulated. Therefore we believed that IGF-1R was the functional target for miR-223 suppression of cell proliferation and its downstream PI3K/Akt/mTOR/p70S6K pathway suppressed by miR-223 was by targeting IGF-1R.     

Inhibition of human parainfluenza virus type 1 sialidase by analogs of 2-deoxy-2,3-didehydro-N-acetylneuraminic acid

Eleven novel analogs of 2-deoxy-2,3-didehydro-N-acetylneuraminic acid (Neu5Ac2en) modified at the C-4 and C-9 positions were designed and tested for their ability to inhibit sialidase of human parainfluenza virus type 1 (hPIV-1). The analogs modified by the cyanomethyl, amidinomethyl, and thiocarbamoylmethyl groups at the C-4 position exhibited potent inhibition against hPIV-1 sialidase compared with Neu5Ac2en. The most effective compound was thiocarbamoylmethyl analog (4-O-thiocarbamoylmethyl-Neu5Ac2en). The activity of 4-O-thiocarbamoylmethyl-Neu5Ac2en causing 50% enzyme inhibition at a concentration of approximately 1.0×10^–5M was 30-fold larger than Neu5Ac2en. While, the analogs of Neu5Ac2en modified by the azido and N-acetyl groups at the C-9 showed a decrease in inhibition of sialidase compared with the 9-hydroxy analogs. In addition, 4-O-thiocarbamoylmethyl-Neu5Ac2en strongly inhibited hPIV-1 infections of Lewis lung carcinoma-monkey kidney cells in comparison with Neu5Ac2en. The present findings would provide useful information for the development of anti-human parainfluenza virus compounds.     

Nordihydroguaiaretic acid (NDGA), an inhibitor of the HER2 and IGF-1 receptor tyrosine kinases, blocks the growth of HER2-overexpressing human breast cancer cells

We have reported that nordihydroguaiaretic acid (NDGA) inhibits the tyrosine kinase activities of the IGF-1 receptor (IGF-1R) and the HER2 receptor in breast cancer cells. Herein, we studied the effects of NDGA on the growth of estrogen receptor (ER) positive MCF-7 cells engineered to overexpress HER2 (MCF-7/HER2-18). These cells are an in vitro model of HER2-driven, ER positive, tamoxifen resistant breast cancer. NDGA was equally effective at inhibiting the growth of both parental MCF-7 and MCF-7/HER2-18 cells. Half maximal effects for both cell lines were in the 10-15 microM range. The growth inhibitory effects of NDGA were associated with an S phase arrest in the cell cycle and the induction of apoptosis. NDGA inhibited both IGF-1R and HER2 kinase activities in these breast cancer cells. In contrast, Gefitinib, an epidermal growth factor receptor inhibitor but not an IGF-1R inhibitor, was more effective in MCF-7/HER2-18 cells than in the parental MCF-7 cells and IGF binding protein-3 (IGFBP-3) was more effective against MCF-7 cells compared to MCF-7/HER2-18. MCF-7/HER2-18 cells are known to be resistant to the effects of the estrogen receptor inhibitor, tamoxifen. Interestingly, NDGA not only inhibited the growth of MCF-7/HER2-18 on its own, but it also demonstrated additive growth inhibitory effects when combined with tamoxifen. These studies suggest that NDGA may have therapeutic benefits in HER2-positive, tamoxifen resistant, breast cancers in humans.