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Purpose: Most lung cancer patients have some resistance to and suffer from side effects of conventional chemotherapy. Thus, identification of a novel anticancer drug with better target selectivity for lung cancer treatment is urgently needed. Experimental Design: In order to investigate whether OSU03013, a derivative of celecoxib, can be a potential drug for lung cancer treatment, we examined its cytotoxicity mechanisms by flow cytometry and phosphatidylserine staining in A549, CL1-1, and H1435 lung cancer cell lines, which are resistant to the conventional drug, cisplatin. In addition, we identified the affected proteins by proteomics and confirmed the selected proteins by Western blot analysis. We examined the interaction between OSU03013 and potential target protein by molecular modeling. Results: Our results indicated that OSU03013 had low-dose (1∼4 μM) cytotoxicity in all lung cancer cell lines tested 48 hours posttreatment. OSU03013 caused cell cycle G1 phase arrest and showed phosphatidylserine early apoptosis via endoplasmic reticulum stress. Several proteins such as heat shock protein 27, 70, and 90, CDC2, α-tubulin, annexin A3, cAMP-dependent protein kinase, glycogen synthase kinase 3-beta, and β-catenin were identified by proteomics and confirmed by Western blot. In addition, molecular modeling showed that OSU03013 competes with ATP to bind to cAMP-dependent protein kinase. Conclusions: We identified for the first time that OSU03013 inhibits cAMP-dependent protein kinase activity and causes dephosphorylation of glycogen synthase kinase 3-beta leading to β-catenin degradation, which is often overexpressed in lung cancer. Our molecular and proteomic results show the potential of OSU03013 as an anticancer drug for lung cancer.

A molecular dynamics simulation of the folding of a short alanine-based helical peptide of 17 residues with three Glu...Lys (i, i + 4) salt bridge pairs, referred to as the AEK17 peptide, was carried out. The simulation gave an estimated simulation folding time of 2.5 ns, shorter than 12 ns for an alanine-based peptide of 16 residues with three Lys residues only, referred to as the AK16 peptide, simulated previously. After folded, the AEK17 peptide had a helical content of 77%, in excellent agreement with the experimentally determined value of 80%. An examination of the folding pathways of AEK17 indicated that the peptide proceeded via three-turn helix conformations more than the helix-turn-helix conformation in the folding pathways. An analysis of interactions indicated that the formation of hydrogen bonds between Lys residue side chains and backbone carbonyls is a major factor in the abundant conformation of the three-turn helix intermediate. The substitution of three Ala with Glu residues reduces the extent of hydrophobic interaction in alanine-based AK peptides with the result that the breaking of the interactions of Lys epsilon-NH3+(side chain)...C=O(backbone) is a major activation action for the AEK17 to achieve a complete fold, in contrast to the AK16 peptide, in which breaking non-native hydrophobic interaction is the rate-determining step.

Both diastereomeric isomers of epoxides with high optical purity are obtained when camphor N-methacryloylpyrazolidinone (1a) and N-tigloylpyrazolidinone (1b) are treated with a urea hydrogen peroxide/TFAA and methyl(trifluoromethyl)dioxirane, respectively.

A new class of hydrogen-bonded ladders based on hydrogen-bonded dimerization of oligo-alpha-aminopryidines has been demonstrated. Jorgensen's model can be successfully applied to this hydrogen-bonding system in nonpolar solvents. The results show the competitive enthalpy/entropy compensation relationship upon dimerization. Although increasing the number of hydrogen-bonding interactions would enhance the hydrogen-bonding stabilization enthalpy, this stabilization enthalpy per unit would be partially sacrificed to compensate for the entropy loss due to dimerization. These results clearly support the importance of preorganization in designing hydrogen-bonding guest-host molecules.

Cardiotoxins are small all-β sheet proteins of 60–62 residues. We carried out molecular dynamics simulation of the cardiotoxin III from Taiwan cobra venom in solution at high temperatures to examine the unfolding pathway(s) of this protein. The hydrogen bonds in the double β sheet of β1–2 strands broken earlier than those in the large triple β sheet of β3–5 strands. This is consistent with the experimental result of folding/unfolding for cardiotoxin III. A transition state was identified using a conformation cluster analysis. In the latter part of the unfolding trajectory, α-helix segments were observed. Finally, an effect of pH dependence in the unfolding of CTX III is discussed.

Background Recent experiments have explored effects of activities of kinases other than the well-studied GSK3β, in wnt pathway signaling, particularly at the level of β-catenin. It has also been found that the kinase PKA attenuates β-catenin degradation. However, the effects of these kinases on the level and degradation of β-catenin and the resulting downstream transcription activity remain to be clarified. Furthermore, the effect of GSK3β phosphorylation on the β-catenin level has not been examined computationally. In the present study, the effects of phosphorylation of GSK3β and of phosphorylations and degradation of β-catenin on the kinetics of the wnt signaling pathway were examined computationally. Methods The well-known computational Lee-Heinrich kinetic model of the wnt pathway was modified to include these effects. The rate laws of reactions in the modified model were solved numerically to examine these effects on β-catenin level. Results The computations showed that the β-catenin level is almost linearly proportional to the phosphorylation activity of GSK3β. The dependence of β-catenin level on the phosphorylation and degradation of free β-catenin and downstream TCF activity can be analyzed with an approximate, simple function of kinetic parameters for added reaction steps associated with effects examined, rationalizing the experimental results. Conclusion The phosphorylations of β-catenin by kinases other than GSK3β involve free unphorphorylated β-catenin rather than GSK3β-phosphorylated β-catenin*. In order to account for the observed enhancement of TCF activity, the β-catenin dephosphorylation step is essential, and the kinetic parameters of β-catenin phosphorylation and degradation need to meet a condition described in the main text. These findings should be useful for future experiments.