Search

Efforts have been made to develop a chemoprevention strategy that selectively triggers apoptosis in malignant cancer cells. Previous studies showed that capsaicin, the major pungent ingredient of red pepper, had differential effect between normal and transformed cells. As an approach to unveil the molecular mechanism by which capsaicin selectively induces apoptosis in transformed cells, we investigated the effect of capsaicin in nontransformed and ras-transformed cells of a common origin: parental (MCF10A) and H-ras-transformed (H-ras MCF10A) human breast epithelial cells. Here, we show that capsaicin selectively induces apoptosis in H-ras-transformed cells but not in their normal cell counterparts. The capsaicin-induced apoptosis, which is dependent on ras transformation, involves the activity of DEVDase (caspase-3 like). In H-ras MCF10A cells, capsaicin treatment markedly activated c-Jun N-terminal protein kinase (JNK)-1 and p38 matigen-activated protein kinase (MAPK) while it deactivated extracellular signal-regulated protein kinases (ERKs). The use of kinase inhibitors and overexpression of dominant-negative forms of MAPKs demonstrated a role of JNK-1 and p38, but not that of ERKs, in apoptosis induced by capsaicin in H-ras-transformed MCF10A cells. Based on the present study, we propose that capsaicin selectively induces apoptosis through modulation of ras-downstream signaling molecules in ras-activated MCF10A cells. Taken in conjunction with the fact that uncontrolled ras activation is probably the most common genetic defect in human cancer cells, our finding may be critical to the chemopreventive potential of capsaicin and for developing a strategy to induce tumor cell-specific apoptosis.

Characterization of poly(butylene adipate-co-succinate) (PBAS)/poly(butylene terephthalate) (PBT) copolyesters resulting from the intermolecular ester-exchange reaction between molten PBAS and PBT have been analyzed using 1H-NMR spectroscopy, differential scanning calorimetry, wide-angle X-ray diffraction, and total organic carbon lab analyzer. Using the assignment of proton resonance due to homogeneous and heterogeneous dyads, the average block lengths were investigated over the entire range of copolymer composition. A decrease in melting temperature was observed with the increase of a terephthalate unit in the composition. The result of X-ray diffraction curve matches well with that of average block length and thermal property. When a rich component is crystallized, the poor component is excluded completely in a crystal formation. The biodegradability in copolyesters also depended on the terephthalate unit in the composition and average block length of the aromatic unit. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 593–608, 1999

Superconductivity in the high-transition-temperature (high-Tc) copper oxides competes with other possible ground states1,2. The physical explanation for superconductivity can be constrained by determining the nature of the closest competing ground state, and establishing if that state is universal among the high-Tc materials. Antiferromagnetism has been theoretically predicted3,4 to be the competing ground state. A competing ground state is revealed when superconductivity is destroyed by the application of a magnetic field, and antiferromagnetism has been observed in hole-doped materials under the influence of modest fields5,6,7,8,9,10,11,12. None of the previous experiments have revealed the quantum phase transition from the superconducting state to the antiferromagnetic state, because they failed to reach the upper critical field Bc2. Here we report the results of transport and neutron-scattering experiments on electron-doped Nd1.85Ce0.15CuO4 (refs 13, 14), where Bc2 can be reached15. The applied field reveals a static, commensurate, anomalously conducting long-range ordered antiferromagnetic state, in which the induced moment scales approximately linearly with the field strength until it saturates at Bc2. This and previous experiments on the hole-doped materials therefore establishes antiferromagnetic order as a competing ground state in the high-Tc copper oxide materials, irrespective of electron or hole doping.