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Until now, there has not been enough information on how androgens or androgen deprivation may influence the response of cancer cells to radiation. In this study, the effect of dihydrotestosterone (DHT) on cellular proliferative activity and radiosensitivity was examined in a hormone-sensitive human prostate cancer cell line, LNCaP. In addition, the study also examined how a heat shock protein 90 (Hsp90) chaperone complex inhibitor modified the effect of DHT on the radiosensitivity of the cells, because binding of the androgen receptor (AR) to Hsp90 is required to maintain the stability and functioning of AR. The hormone-sensitive human prostate cancer cell line, LNCaP, was used. Radicicol was used as one of the known Hsp90 chaperone complex inhibitors, and the cells were incubated in the presence of this compound at a concentration of 500 nM. Cellular radiosensitivity was determined by the clonogenic assay; the changes in the protein expression were examined by Western blotting or immunofluorescence. DHT at a concentration of 1 nM caused enhancement of the proliferative activity and reduction of the radiosensitivity of the cells. Radicicol at a concentration of 500 nM abolished the DHT-induced decrease in cellular radiosensitivity and potentiated the radiation-induced cell killing synergistically. Consistent with the changes in the cellular radiosensitivity, radicicol degraded AR, Raf-1 and HER2/neu via reduced binding of AR to Hsp90, although selective degradation of HER2/neu caused by Herceptin, a monoclonal antibody against HER2, did not affect the cellular radiosensitivity. The results suggest that the Hsp9O chaperone complex may be a potential molecular target for potentiation of radiation-induced cell killing in a hormone-sensitive prostate cancer cell line.

The synthesis and crystal structure of the α-pyrrolidonate-bridged binuclear complex [Pt 2 (bpy) 2 (α-pyrrolidonato) 2 ](ClO 4 ) 2 are reported. The complex is prepared by the reaction of Pt(bpy)Cl 2 with α-pyrrolidone in H 2 O. The complex crystallizes in monoclinic, space group C 2 /c , a =29.992(4), b =12.430(1), c =18.842(3) A, β=112.191(8)°, Z =8, V =6504(2) A 3 . The structure was refined with 4033 independent reflections to R =0.079. The complex is a head-to-tail binuclear structure, bridged by nitrogen and oxygen atoms of the two α-pyrrolidonate ligands. No isomerization to a head-to-head isomer was observed in acetonitrile which was confirmed with 1 H- 13 C COSY NMR spectrometry. Cyclic voltammetry exhibited an irreversible wave at E pa =1.19 and E pc =0.84 V versus SCE in acetonitrile. FAB mass spectroscopy showed major peaks corresponding to the molecular formula, and proved the applicability of the method for the determination of the molecular weights of this sort of cationic complex.

To examine the ability of a heat shock protein 90 (Hsp90) chaperone complex inhibitor, radicicol, to modify thermal response and heat-induced cell killing, and to clarify the underlining mechanisms.A human oesophageal cancer cell line (TE-1), with a mutant p53 gene, was used. To examine the effect of radicicol on heat-induced cell killing, radicicol at a concentration of 100 nM was incubated with the cells for 7 h during heat treatment. Changes in the expression of proteins were examined by Western blot and immunofluorescence analysis.Radicicol in combination with heat synergistically potentiated heat-induced cellular killing despite an increase in the expression of Hsp72 and Hsp27 caused by radicicol. Heat alone activated Raf-1 and p42/p44 extracellular signal-regulated kinase (Erk), and heat in combination with radicicol inhibited the activation of Raf-1 and p42/p44 Erk through reduced binding of Raf-1 to Hsp90. Phosphorylation of Akt was also decreased by radicicol.The Hsp90 chaperone complex inhibitor, radicicol, potentiated heat-induced cellular killing, and inhibition of p42/p44 Erk and Akt activation rather than modification of Hsp expression might be involved in enhancing cellular thermosensitivity. Results suggest that the Hsp90 chaperone complex could be a new molecular target for the modification of the cellular response to heat.

Device design and deposition conditions of a-Si/a-SiGe/a-SiGe triple-junction solar cells were studied. To optimize their device structure, we applied several technologies such as a-SiO:H window p-layer for top cell, low temperature deposited /spl mu/c-Si p-layer for middle/bottom cells and hydrogen-dilution technique for a-SiGe:H i-layers. As a result, we obtained 1 cm/sup 2/ cell with 11% stabilized efficiency. We found out effective deposition parameters such as increasing both hydrogen-dilution ratio and RF-power for Ge/Si>0.5. In addition, we presented newly designed apparatus for the triple-junction 40 cm/spl times/80 cm solar cells.

The most important function of carotenoid pigments, especially beta-carotene in higher plants, is to protect organisms against photooxidative damage (G. Britton, in T. W. Goodwin, ed., Plant Pigments--1988, 1988; N. I. Krinsky, in O. Isler, H. Gutmann, and U. Solms, ed., Carotenoids--1971, 1971). beta-Carotene also functions as a precursor of vitamin A in mammals (G. A. J. Pitt, in I. Osler, H. Gutmann, and U. Solms, ed., Carotenoids--1971, 1971). The enzymes and genes which mediate the biosynthesis of cyclic carotenoids such as beta-carotene are virtually unknown. We have elucidated for the first time the pathway for biosynthesis of these carotenoids at the level of enzyme-catalyzed reactions, using bacterial carotenoid biosynthesis genes. These genes were cloned from a phytopathogenic bacterium, Erwinia uredovora 20D3 (ATCC 19321), in Escherichia coli and located on a 6,918-bp fragment whose nucleotide sequence was determined. Six open reading frames were found and designated the crtE, crtX, crtY, crtI, crtB, and crtZ genes in reference to the carotenoid biosynthesis genes of a photosynthetic bacterium, Rhodobacter capsulatus; only crtZ had the opposite orientation from the others. The carotenoid biosynthetic pathway in Erwinia uredovora was clarified by analyzing carotenoids accumulated in E. coli transformants in which some of these six genes were expressed, as follows: geranylgeranyl PPiCrtB----prephytoene PPiCrtE----phytoeneCrtI---- lycopeneCrtY----beta-caroteneCrtZ----zeaxanthinCrtX--- -zeaxanthin-beta- diglucoside. The carotenoids in this pathway appear to be close to those in higher plants rather than to those in bacteria. Also significant is that only one gene product (CrtI) for the conversion of phytoene to lycopene is required, a conversion in which four sequential desaturations should occur via the intermediates phytofluene, zeta-carotene, and neurosporene.

action of VRL. Flow cytometry exhibited cell cycle arrest at G2/M phase. After PDT there was overexpression of anti-apoptotic gene bcl-2. VRL caused downregulation of bcl-2 by phosphorylation and upregulated proapoptotic Bax circumventing resistance to chemotherapy and photocytotoxicity. Irradiation generated oxidative stress stimuli such as reactive oxygen species where an electron transfer event is the initial step for type-I photoinduced damage and predominantly singlet oxygen where an energy transfer reaction from the photoexcited molecule to molecular oxygen is the initial step of type-II biological damage causing tumoral cell death under a ratio of apoptosis versus necrosis. Singlet oxygen as the major mediator of cytotoxicity in PDT induces c-fos and c-jun and activates p38 which phosphorylates transcription factors such as ATF-2 and Elk-1. Photosensitization mediated oxidative stress downregulated MDR-1, MMP-9 and VEGF while it induced proapoptotic genes c-myc and WAF1/CIP1/p21 causing arrest of cell cycle in tumor cells through inhibition of cdk2, cdk6, cyclin D1 and cyclin E. Stress induced second messenger ceramide of the acidic sphingomyelinase was activated stimulating cell death signals. Porfimer sodium exerts its photoactivity to the proteins and lipids of plasma membranes, ER, nuclei and mitochondria where light activation damages irreversibly membranes and reduces the activity of membrane associated enzymes like succinic dehydrogenase. We detect a drop in mitochondrial potential concurrent with a drop in ATP level reducing cell respiration. Release of cyt-c from mitochondria into the cytosol initiates mitochondria associated apoptotic events in tumor cells. This causes an irreversible loss of mitochondrial membrane potential revealed by TMRM. Caspase assays revealed activation of procaspase-3 activity via complex formation with dATP, Apaf-1 and cleavage of procaspase-9. Caspase-3 induces apoptosis causing cleavage of a number of proteins including DFF, PARP, DNA ladder formation, TUNEL cells and DEVDase activity. PCD was also confirmed with TdT assay and DNA elution assay. The majority of tumor cells were eradicated by PCD according to counting DAP1 stained nuclei and FITC cells by fluorescence microscopy. Furthermore, PCD was evaluated with propidium iodide staining and flow cytometry with annexin-V. Irreversible D2 apoptotic signs were exhibited with TEM & SEM. Exposure of phosphatidylserine on the plasma membrane of apoptotic cells activated their phagocytosis by adjacent tumor cells indicating a bystander killing effect. Cytotoxicity was revealed by MTT and BrdU assays measuring metabolic activity and DNA synthesis of tumor and endothelial cells which inhibited angiogenesis.