Quasi-Phase Diagrams at Air/Oil Interfaces and Bulk Oil Phases for Crystallization of Small-Molecular Semiconductors by Adjusting Gibbs Adsorption.

The temperature and concentration dependencies of the crystallization of two small-molecular semiconductors were clarified by constructing quasi-phase diagrams at air/oil interfaces and in bulk oil phases. A quinoidal quaterthiophene derivative with four alkyl chains (QQT(CN)4) in 1,1,2,2-tetrachroloethane (TCE) and a thienoacene derivative with two alkyl chains (C8-BTBT) in o-dichlorobenzene were used. The apparent crystal nucleation temperature (Tn) and dissolution temperature (Td) of the molecules were determined based on optical microscopy examination in closed glass capillaries and open dishes during slow cooling and heating processes, respectively. Tn and Td were considered estimates of the critical temperatures for nuclear formation and crystal growth, respectively. The Tn values of QQT(CN)4 and C8-BTBT at the air/oil interfaces were higher than those in the bulk oil phases, whereas the Td values at the air/oil interfaces were almost the same as those in the bulk oil phases. These Gibbs adsorption phenomena were attributed to the solvophobic effect of the alkyl chain moieties. The temperature range between Tn and Td corresponds to suitable supercooling conditions for ideal crystal growth based on the suppression of nucleation. The Tn values at the water/oil and oil/glass interfaces did not shift compared with those of the bulk phases, indicating that adsorption did not occur at the hydrophilic interfaces. Promotion and inhibition of nuclear formation for crystal growth of the semiconductors were achieved at the air/oil and hydrophilic interfaces, respectively.

Novel thermo-responsive coloring phenomena in water/surfactant/oil emulsions.

Emulsions comprising a dual-surfactant system of a long-chain amidoamine derivative and a quaternary ammonium salt developed an iridescent color at a specific temperature region. The emulsions underwent phase inversion on heating from an O/W emulsion to a W/O emulsion, passing through a periodical lamellar structure which developed a characteristic interference color. Interestingly, the color and the coloring temperature can be independently controlled by adjusting the concentration of surfactants, respectively.

HOXD3-overexpression increases integrin alpha v beta 3 expression and deprives E-cadherin while it enhances cell motility in A549 cells.

We have previously shown that transduction of HOXD3, one of homeobox genes, into human lung cancer A549 cells enhances cell motility, invasion and metastasis. In the present study, we examined the roles of integrin beta3 which was up-regulated by HOXD3-overexpression in the HOXD3-induced motility of A549 cells. We first established integrin beta3-transfectants and compared their motile activity to those of the HOXD3-transfected, control-transfected and parental cells by three different assays. The integrin beta3-transfectants as well as the HOXD3-transfectants formed heterodimer with integrin alphav subunit, and showed highly motile activities assessed by haptotaxis or phagokinetic track assay compared to the control transfectants or parental cells. In vitro wound-healing assay revealed that migratory activities were graded as the HOXD3-transfectants > the integrin beta3-transfectants > the control transfectants or parental cells. E-cadherin was expressed in the integrin beta3-transfectants but not expressed in the HOXD3-transfectants. An addition of function-blocking antibody to E-cadherin into the wound-healing assay promoted the migratory activity of the integrin beta3-transfectants, suggesting that E-cadherin prevented the cells from dissociating from the wound edges. These results indicate that increased expression of integrin alphav beta3 and loss of E-cadherin by HOXD3-overexpression are responsible for the enhanced motility and dissociation.

Metal-organic thin-film transistor (MOTFT) based on a bis(o-diiminobenzosemiquinonate) nickel(II) complex.

The semiconducting film based on bis(o-diiminobenzosemiquinonate) nickel(II) complex showed uniaxial orientation structure along the normal to the substrate and good p-type metal-organic thin-film transistor (MOTFT) character.

Epigenetic silencing of E- and P-cadherin gene expression in human melanoma cell lines.

The degree of E- and P-cadherin expressions inversely correlate with the progression stage of human melanoma. In the present study, we analyzed mechanisms of down-regulation of E- and P-cadherin gene expressions in 8 human melanoma cell lines. In 5 of the 8 melanoma cell lines, E-cadherin expression was lost or markedly decreased compared to that in normal melanocytes, and 4 of the 5 melanoma cell lines lost P-cadherin expression. All of the melanoma cell lines expressed snail, which is known to encode a transcription repressor for E-cadherin, at a higher level than melanocytes whereas expression levels of the snail varied among cell lines. Transduction of snail gene into MMAc cells which expressed a high level of E-cadherin and an extremely low level of snail decreased expression of E-cadherin but not P-cadherin. In contrast, transduction of antisense-snail gene into A375M cells which expressed no E-cadherin and a high level of snail restored expression of E-cadherin but not P-cadherin. Methylation-specific PCR analysis revealed CpG methylation in the promoter region of E-cadherin of MeWo and AKI cells. Further, the treatment with a demethylating agent, 5-azacytidine led AKI and A375M cells to re-express both E- and P-cadherin. The results show E-cadherin gene is silenced by at least two distinct mechanisms (methylation and transrepression by Snail) in human melanoma cell lines whereas P-cadherin gene seems to be silenced by methylation but not by snail.

Reconstructed beta-catenin/TCF4 signaling in yeast applicable to functional evaluation of APC mutations.

In human genetics and molecular oncology, mutation research is necessary not only to identify mutations in nucleic acid sequences, but also to analyze the loss of function caused by mutant proteins. We reconstructed a protein-protein network system of human beta-catenin and TCF4, in Saccharomyces cerevisiae. beta-Catenin and TCF4 proteins form a complex and transactivate reporter genes. Co-expressed wild-type APC with beta-catenin and TCF4 inhibit the transcriptional activity of the beta-catenin/TCF4 complex in yeast, as well as in mammals. This unique method in which the beta-catenin/TCF4 signaling pathway is reconstructed in vivo may prove useful for the functional evaluation of APC mutants, including a type of APC truncated and missense mutants influenced to the ability of binding to beta-catenin.

Molecular cloning of p53 cDNA of Mongolian gerbil and establishment of yeast p53 functional assay system.

BACKGROUND: Epidemiological studies have shown a correlation between Helicobacter pylori infection and human gastric carcinogenesis. A Mongolian gerbil model has demonstrated that H. pylori infection induced gastric carcinoma. However, the disadvantage of this animal model is a lack of information regarding the cellular genes involved in oncogenesis. Mutation of the p53 gene is one of the most common steps in gastric carcinogenesis. In this study, we aimed to clone the p53 gene of the Mongolian gerbil and detect the functional mutations in H. pylori-infected animals. MATERIALS AND METHODS: The p53 complementary DNA (cDNA) of Mongolian gerbil was cloned by the methods of reverse-transcribed polymerase chain reaction and rapid amplification of cDNA ends. RESULTS: The p53 cDNA of Mongolian gerbil has a 78.8% homology to that of humans. A novel yeast p53 assay system was established and enabled to detect the functional mutations of the p53 gene in the stomach of the Mongolian gerbil. CONCLUSIONS: This is the first report of the complete sequence of wild-type p53 cDNA of the Mongolian gerbil. This genetic information and an assay system designed to detect the functional mutations of the p53 gene are useful for further investigations of gastric oncogenesis in this animal model.

Transduction of HOXD3-antisense into human melanoma cells results in decreased invasive and motile activities.

Homeobox genes regulate sets of genes that determine cellular fates in embryonic morphogenesis and maintenance of adult tissue architecture by regulating cellular motility and cell-cell interactions. Our previous studies showed that a specific member, HOXD3, when overexpressed, enhanced cell motility and invasiveness of human lung cancer A549 cells (Hamada et al. Int. J. Cancer 2001; 93: 516-25 [19]). In the present study, we investigated the roles of HOXD3 in motile and invasive behavior of human malignant melanoma cells. Of seven melanoma cell lines examined here, six cell lines expressed the HOXD3 gene, whereas normal melanocytes did not. We transduced the HOXD3-antisense gene expression vector into two cell lines (A375M and MMIV). The cell transduced with the HOXD3-antisense gene showed reduced in vitro invasion of Matrigel. The transduction of the HOXD3-antisense gene also decreased cell spreading, haptotactic activity to vitronectin and laminin-1, and phagokinetic activity. To find the difference of gene expression between the HOXD3-antisense-transduced A375M cells and the control A375MNeo2 cells, we carried out cDNA microarray analysis. The results of the microarray analysis indicated that the increased expression of cdc42-interacting protein 4, KIAA0554 and tropomyosin 1, which are all associated with the cytoskeletal system, may be involved in the reduction of motile and invasive activity by the HOXD3-antisense gene transduction.

Thymosin-beta4 regulates motility and metastasis of malignant mouse fibrosarcoma cells.

We identified a thymosin-beta4 gene overexpression in malignant mouse fibrosarcoma cells (QRsP-30) that were derived from clonal weakly tumorigenic and nonmetastatic QR-32 cells by using a differential display method. Thymosin-beta4 is known as a 4.9-kd polypeptide that interacts with G-actin and functions as a major actin-sequestering protein in cells. All of the six malignant fibrosarcoma cell lines that have been independently converted from QR-32 cells expressed high levels of thymosin-beta4 mRNA and its expression in tumor cells was correlated with tumorigenicity and metastatic potential. Up-regulation of thymosin-beta4 in QR-32 cells (32-S) transfected with sense thymosin-beta4 cDNA converted the cells to develop tumors and formed numerous lung metastases in syngeneic C57BL/6 mice. In contrast, antisense thymosin-beta4 cDNA-transfected QRsP-30 (30-AS) cells reduced thymosin-beta4 expression, and significantly lost tumor formation and metastases to distant organs. Vector-alone transfected cells (32-V or 30-V cells) behaved like their parental cells. We observed that tumor cell motility, cell shape, and F-actin organization is regulated in proportion to the level of thymosin-beta4 expression. These findings indicate that thymosin-beta4 molecule regulates fibrosarcoma cell tumorigenicity and metastasis through actin-based cytoskeletal organization.