Expression and role of phosphodiesterase 3 in human squamous cell carcinoma KB cells

An efficient and ecofriendly synthesis of highly functionalized pyridones via a one-pot three-component reaction

A simple and convenient protocol has been developed for the synthesis of N-amino-3-cyano-2-pyridone derivatives by a one-pot reaction of cyanoacetohydrazide, activated nitrile substrates (malononitrile, ethyl cyanoacetate, cyanoacetamide) and aromatic aldehydes in the presence of piperidine in water or a mixture of water and ethanol. The sequence of cascade reactions includes Knoevenagel condensation, Michael addition, intramolecular cyclization, imine-enamine tautomerization and oxidative aromatization. The main advantages of this procedure are availability of starting compounds, simple procedure, mild conditions, easy purification of products and the use of water or water/ethanol as green solvents.

Role of phosphodiesterase 2 in growth and invasion of human malignant melanoma cells

Cyclic nucleotide phosphodiesterases (PDEs) regulate the intracellular concentrations and effects of adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP). The role of PDEs in malignant tumor cells is still uncertain. The role of PDEs, especially PDE2, in human malignant melanoma PMP cell line was examined in this study. In PMP cells, 8-bromo-cAMP, a cAMP analog, inhibited cell growth and invasion. However, 8-bromo-cGMP, a cGMP analog, had little or no effect. PDE2 and PDE4, but not PDE3, were expressed in PMP cells. Growth and invasion of PMP cells were inhibited by erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA), a specific PDE2 inhibitor, but not by rolipram, a specific PDE4 inhibitor. Moreover, cell growth and invasion were inhibited by transfection of small interfering RNAs (siRNAs) specific for PDE2A and a catalytically-dead mutant of PDE2A. After treating cells with EHNA or rolipram, intracellular cAMP concentrations were increased. Growth and invasion were stimulated by PKA14-22, a PKA inhibitor, and inhibited by N(6)-benzoyl-c AMP, a PKA specific cAMP analog, whereas 8-(4-chlorophenylthio)-2'-O-methyl-cAMP, an Epac specific cAMP analog, did not. Invasion, but not growth, was stimulated by A-kinase anchor protein (AKAP) St-Ht31 inhibitory peptide. Based on these results, PDE2 appears to play an important role in growth and invasion of the human malignant melanoma PMP cell line. Selectively suppressing PDE2 might possibly inhibit growth and invasion of other malignant tumor cell lines.

Discovery of colon tumor cell growth inhibitory agents through a combinatorial approach

Two series with the general formula of 4,6-diaryl-2-oxo-1,2 dihydropyridine-3-carbonitriles and their isosteric 4,6-diaryl-2-imino-1,2-dihydropyridine-3-carbonitrile were synthesized through one pot reaction of the appropriate acetophenone, aldehyde, ammonium acetate with ethyl cyanoacetate or malononitrile, respectively. The synthesized compounds were evaluated for their tumor cell growth inhibitory activity against the human HT-29 colon tumor cell line, as well as their PDE3 inhibitory activity. Compound 4-(2-Ethoxyphenyl)-2-oxo-6-thiophen-3-yl-1,2-dihydropyridine-3 carbonitrile (21) showed tumor cell growth inhibitory activity with an IC50 value of 1.25 microM. Meanwhile, 4-(4-Ethoxyphenyl)-2-imino-6-(thiophen-3-yl)-1,2-dihydropyridine-3-carbonitrile (26) showed inhibitory effect upon PDE3 using cAMP or cGMP as substrate. No correlation exists between PDE3 inhibition and the tumor cell growth inhibitory activity. Docking compound 21 to other possible molecular targets showed the potential to bind PIM1 Kinase.

Phenotype-based screening of mechanistically annotated compounds in combination with gene expression and pathway analysis identifies candidate drug targets in a human squamous carcinoma cell model

The squamous cell carcinoma HeLa cell line and an epithelial cell line hTERT-RPE with a nonmalignant phenotype were interrogated for HeLa cell selectivity in response to 1267 annotated compounds representing 56 pharmacological classes. Selective cytotoxic activity was observed for 14 of these compounds dominated by cyclic adenosine monophosphate (cAMP) selective phosphodiesterase (PDE) inhibitors, which tended to span a representation of the chemical descriptor space of the library. The PDE inhibitors induced delayed cell death with features compatible with classical apoptosis. The PDE inhibitors were largely inactive when tested against a cell line panel consisting of hematological and nonsquamous epithelial phenotypes. In a genome-wide DNA microarray analysis, PDE3A and PDE2A were found to be significantly increased in HeLa cells compared to the other cell lines. The pathway analysis software PathwayAssist was subsequently used to extract a list of proteins and small molecules retrieved from Medline abstracts associated with the hit compounds. The resulting list consisted of major parts of the cAMP-protein kinase A pathway linking to ERK, P38, and AKT. This molecular network may provide a basis for further exploitation of novel candidate targets for the treatment of squamous cell carcinoma.