Showing papers by "Kyushu University published in 1995"

Assembly of multicomponent protein films by means of electrostatic layer-by-layer adsorption

Abstract: Multilayer films which contain ordered layers of more than one protein species were assembled by means of altemate electrostatic adsorption mostly with positively charged poly(ethy1enimine) (PEI) or with negatively charged poly(styrenesu1fonate) (PSS). Water-soluble proteins used are cytochrome c (Cyt), myoglobin (Mb), lysozyme (Lys), histone f3, hemoglobin (Hb), glucoamylase (GA), and glucose oxidase (GOD). Charged protein layers formed multilayers with linear polymers acting as glue or filler. The assembly was monitored by a quartz crystal microbalance and W spectroscopy. Linear film growth was observed up to at least 25 molecular layers. The assembly of Mb and Lys, both positively-charged, was realized in altemation with PSS in the form of {PEI/PSS + (Mb/PSS)2 + (MbPSS/Lys/PSS)d}. The assembly of oppositely-charged (at pH 6.5) Lys and GOD consists from Lys and GOD layers separated by a polycatiodpolyanion bilayer: {PEYPSSPEI f (PSS/Lys)2 + PSSPEI f (GOD/PEI)6}. Hb was assembled as “positive” unit at pH 4.5 (in alternation with PSS) and as “negative” unit at pH 9.2 (in altemation with PEI). A multilayer consisting of alternating montmorillonite, PEI, and GOD layers was also assembled. These biomolecular architecture open a way to construct artificially orchestrated protein systems that can carry out complex enzymic reactions.

Reduced hippocampal LTP and spatial learning in mice lacking NMDA receptor ε1 subunit

Abstract: THE NMDA (TV-methyl-D-aspartate) receptor channel is important for synaptic plasticity, which is thought to underlie learning, memory and development1, 2. The NMDA receptor channel is formed by at least two members of the glutamate receptor (GluR) channel subunit families, the GluRe (NR2) and GiuRζ (NR1) sub-unit families3–8. The four e subunits are distinct in distribution, properties and regulation5–14. On the basis of the Mg2+ sensitivity and expression patterns, we have proposed that the ei (NR2A) and e2 (NR2B) subunits play a role in synaptic plasticity6, 14. Here we show that targeted disruption of the mouse el subunit gene resulted in significant reduction of the NMDA receptor channel current and long-term potentiation at the hippocampal CA1 synapses. The mutant mice also showed a moderate deficiency in spatial learning. These results support the notion that the NMDA receptor channel-dependent synaptic plasticity is the cellular basis of certain forms of learning.

Mutant ras oncogenes upregulate VEGF/VPF expression: implications for induction and inhibition of tumor angiogenesis.

Abstract: The growth of solid tumors in vivo beyond 1-2 mm in diameter requires induction and maintenance of an angiogenic response. This can occur through the release of various angiogenic growth factors from tumor cells. One such factor is vascular endothelial growth factor/vascular permeability factor (VEGF/VPF), a secreted and specific mitogen for vascular endothelial cells. We show that one of the most commonly encountered genetic changes detected in human cancer, i.e., expression of mutant ras oncogenes, is associated with marked up-regulation of VEGF/VPF in transformed epithelial cells. Thus, elevation of the levels of both VEGF/VPF mRNA and secreted functional protein were detected in human and rodent tumor cell lines expressing mutant K-ras or H-ras oncogenes, respectively. Genetic disruption of the mutant K-ras allele in human colon carcinoma cells was associated with a reduction in VEGF/VPF activity. Furthermore, pharmacological disruption of mutant RAS protein function in H-ras transformed rat intestinal epithelial cells by treatment with L-739,749 (a protein farnesyltransferase inhibitor) caused a significant suppression of VEGF/VPF. The results suggest that dominantly acting ras oncogenes may contribute to the growth of solid tumors in vivo not only by a direct effect on tumor cell proliferation but also indirectly, i.e., by facilitating tumor angiogenesis. Hence, pharmacologically targeting mutant ras oncogenes could conceivably suppress solid tumor growth in vivo, in part, by inhibiting tumor-induced angiogenesis.

Incidence and risk factors of vascular dementia and Alzheimer's disease in a defined elderly Japanese population The Hisayama Study

Abstract: We followed 828 nondemented residents of Hisayama Town, Kyushu, Japan, aged 65 years or older (88.3% of the elderly population) for 7 years starting in 1985 in order to determine the type-specific incidence of dementia and its risk factors in the general Japanese population. Only two subjects were lost to the follow-up, during which period 103 subjects developed dementia. Morphologic examination of the brains of 89 subjects (86.4%) was made by autopsy or CT. We made the initial diagnosis of dementia based on the DSM-III-R criteria, with the diagnoses of vascular dementia (VD) being based on the NINDS-AIREN criteria and Alzheimer's disease (AD) on the NINCDS-ADRDA criteria. The incidence of VD and AD increased with age for both sexes. The age-adjusted total incidence (per 1,000 person-years) of dementia was 19.3 for men and 20.9 for women. The corresponding rates for VD were 12.2 for men and 9.0 for women, and for AD, 5.1 for men and 10.9 for women. Among the VD subjects whose brain morphology we examined, the most frequent type of stroke was multiple lacunar infarcts (42%), but half these subjects lacked a stroke episode in their histories. Multivariate analysis showed that age, prior stroke episodes, systolic blood pressure, and alcohol consumption were significant independent risk factors for the occurrence of VD. In contrast, age and a low score on Hasegawa's dementia scale were significant risk factors for AD, and physical activity was a significant preventive factor for AD.(ABSTRACT TRUNCATED AT 250 WORDS)

Neural regulation of thermotaxis in Caenorhabditis elegans

Abstract: Thermal stimulus is an important environmental factor influencing animal behaviour. However, the mechanisms underlying thermosensation and thermal adaptation are poorly understood. The nematode Caenorhabditis elegans can sense a range of environmental temperatures and migrate towards the cultivation temperature on a thermal gradient. This modifiable thermotactic response provides an ideal system for studying the cellular and molecular processes involved in thermosensation and thermal information storage. We have identified neurons critical for thermotaxis by killing individual cells in live animals. The results indicate that an amphid sensory neuron, AFD, is a major thermosensory neuron. Some of the genetically defined cryophilic and thermophilic mutant phenotypes were mimicked when amphid interneurons AIY and AIZ, respectively, were killed, indicating that AIY is responsible for thermophilic movement and AIZ for cryophilic movement. We propose a neural model in which regulation of the activities of the two interneurons in opposite directions, depending on the cultivation temperature, is essential for thermotaxis.

Wetting effects on the spreading of a liquid droplet colliding with a flat surface: Experiment and modeling

Abstract: In this paper an experimental and theoretical study of the deformation of a spherical liquid droplet colliding with a flat surface is presented. The theoretical model accounts for the presence of inertia, viscous, gravitation, surface tension, and wetting effects, including the phenomenon of contact‐angle hysteresis. Experiments with impingement surfaces of different wettability were performed. The study showed that the maximum splat radius decreased as the value of the advancing contact angle increased. The effect of impact velocity on droplet spreading was more pronounced when the wetting was limited. The experimental results were compared to the numerical predictions in terms of droplet deformation, splat radius, and splat height. The theoretical model predicted well the deformation of the impacting droplet, not only in the spreading phase, but also during recoiling and oscillation. The wettability of the substrate upon which the droplet impinges was found to affect significantly all phases of the spre...

A giant nucleopore protein that binds Ran/TC4.

Abstract: RAN/TC4 is a small nuclear G protein1 that forms a complex with the chromatin-bound guanine nucleotide release factor RCC1 (ref. 2). Loss of RCC1 causes defects in cell cycle progression3,4, RNA export5-7 and nuclear protein import8. Some of these can be suppressed by overexpression of Ran/TC4 (ref. 1), suggesting that Ran/TC4 functions downstream of RCC1. We have searched for proteins that bind Ran/TC4 by using a two-hybrid screen, and here we report the identification of RanBP2, a novel protein of 3,224 residues. This giant protein comprises an amino-terminal 700-residue leucine-rich region, four RanBPl-homologous (refs 9, 10) domains, eight zinc-finger motifs similar to those of NUP153 (refs 11, 12), and a carboxy terminus with high homology to cyclophilin13. The molecule contains the XFXFG pentapeptide motif characteristic of nuclear pore complex (NPC) proteins14, and immunolocalization suggests that RanBP2 is a constituent of the NPC. The fact that NLS-mediated nuclear import can be inhibited by an antibody directed against RanBP2 supports a functional role in protein import through the NPC.

Neuropathological Diagnostic-criteria for Creutzfeldt-jakob-disease (cjd) and Other Human Spongiform Encephalopathies (prion Diseases)

Abstract: Neuropathological diagnostic criteria for Creutzfeldt-Jakob disease (CJD) and other human transmissible spongiform encephalopathies (prion diseases) are proposed for the following disease entities: CJD - sporadic, iatrogenic (recognised risk) or familial (same disease in 1st degree relative): spongiform encephalopathy in cerebral and/or cerebellar cortex and/or subcortical grey matter; or encephalopathy with prion protein (PrP) immunoreactivity (plaque and/or diffuse synaptic and/or patchy/perivacuolar types). Gerstmann-Straussler-Scheinker disease (GSS) (in family with dominantly inherited progressive ataxia and/or dementia): encephalo(myelo)pathy with multicentric PrP plaques. Familial fatal insomnia (FFI) (in member of a family with PRNP178 mutation): thalamic degeneration, variable spongiform change in cerebrum. Kuru (in the Fore population). Without PrP data, the crucial feature is the spongiform change accompanied by neuronal loss and gliosis. This spongiform change is characterised by diffuse or focally clustered small round or oval vacuoles in the neuropil of the deep cortical layers, cerebellar cortex or subcortical grey matter, which might become confluent. Spongiform change should not be confused with non-specific spongiosis. This includes status spongiosus (''spongiform state''), comprising irregular cavities in gliotic neuropil following extensive neuronal (including also lesions of ''burnt-out'' ''spongy'' changes in brain oedema and metabolic encephalopathies, and artefacts such as superficial cortical, perineuronal, or perivascular vacuolation; focal changes indistinguishable from spongiform change may occur in some cases of Alzheimer's and diffuse Lewy body diseases. Very rare cases might not be diagnosed by these criteria. Then confirmation must be sought by additional techniques such as PrP immunoblotting, preparations for electron microscopic examination of scrapie associated fibrils (SAF), molecular biologic studies, or experimental transmission.

Remarkable N2-fixing bacterial diversity detected in rice roots by molecular evolutionary analysis of nifH gene sequences.

Abstract: To demonstrate the extent of phylogenetic diversity of diazotrophic bacteria associated with rice roots, we characterized phylogenetically 23 nifH gene sequences obtained by PCR amplification of mixed organism DNA extracted directly from rice roots without culturing the organisms. The analyses document the presence of eight novel NifH types, which appear to be a variety of significant components of the diazotrophic community, dominated mainly by proteobacteria.

Detection of cancer micrometastases in lymph nodes by reverse transcriptase-polymerase chain reaction

Abstract: There are few DNA-based studies that detect cancer micrometastases in lymph nodes. We have assayed for the specific detection of carcinoembryonic antigen (CEA)-expressing carcinoma cells in the lymph nodes of patients with gastrointestinal or breast carcinomas. A CEA-specific nested reverse transcriptase (RT)-PCR assay was optimized using limiting dilutions of a CEA-positive cancer cell line mixed with normal lymphocytes. The expression of CEA mRNA was studied in 100 carcinoma tissues, 75 normal mucosal tissues, and 15 lymph nodes from patients with cholelithiasis. Each of 117 lymph nodes from 13 patients with carcinoma was divided into two pieces: one was used for histological examination and the other for RT-PCR, and the results were compared. The sensitivity ratio was one CEA-expressing cancer cell detected in 1 × 10 5 normal lymphocytes. All carcinoma tissues and normal mucosal tissues expressed CEA mRNA, while no amplification was detected in any control lymph nodes. Thirty of 117 lymph nodes were histologically involved by carcinoma cells, and all of these yielded the expected product by RT-PCR. Of the remaining 87 histologically negative nodes, CEA mRNA was detected in 47 lymph nodes by RT-PCR. The positive rate increased from 26% by histological examination to 66% by RT-PCR. The assay by CEA-specific nested RT-PCR is not only sensitive but widely applicable for the detection of cancer micrometastases in lymph nodes. This method may lead to an earlier diagnosis and treatment of patients with subclinical lymph node metastasis.

The reeler gene encodes a protein with an EGF-like motif expressed by pioneer neurons.

Abstract: We have identified a strong candidate cDNA for the mouse reeler gene. This 5 kb transcript encodes a 99.4 kD protein consisting of 881 amino acids and possessing two EGF–like motifs. We assayed two independent mutant alleles — ‘Jackson reeler’, which has a deletion of the entire gene, and ‘Orleans reeler’ which exhibits a 220 bp deletion in the open reading frame, including the second EGF–like motif and resulting in a frame shift. In situ hybridization reveals that the transcript is detected exclusively in the pioneer neurons which guide neuronal cell migration along the radial array. Our findings offer an explanation for how the reeler mutant phenotype causes a disturbance of the complex architecture of the neuronal network.

Gaussian multiterminal source coding

Abstract: We consider the problem of separate coding for two correlated memoryless Gaussian source. We determine the rate-distortion region in a special case that one source plays a role of partial side information to reproduce sequences emitted from the other source with a prescribed average distortion level. We also derive an explicit outer bound of the rate-distortion region, demonstrating that the inner bound obtained by Berger (1978) partially coincides with the rate-distortion region.

Near-surface alignment of polymers in rubbed films

Abstract: RUBBED polymer films (generally polyimides) are used in flat-panel displays to control the alignment of liquid crystals in contact with the polymer1–8, a phenomenon first discovered by Maugin1 in 1911. Buffing the film with a cloth produces liquid-crystal alignment in the rubbing direction. Several mechanisms have been proposed to explain this effect. The generation of microgrooves or scratches on the polymer surface during rubbing has led to the suggestion that alignment is the result of long-range elastic effects induced by these surface features3–5. Others have suggested that the polymer chains near the surface are aligned during rubbing and that these then serve as templates for liquid-crystal alignment6–13. Other studies 10–l2 have implied that both mechanisms might be operative. Here we present X-ray scattering measurements which show unambiguously that rubbing a polyimide film causes near-surface alignment of the polymer molecules. For a film 200 nm thick, most of the polymer chains within a thin surface region (about 5 nm thick) are aligned in the rubbing direction; for a 6-nm film essentially all of the chains are aligned within 20° of the rubbing direction. This marked orientation of the near-surface chains at temperatures far below the bulk glass transition temperature shows that the mechanical properties of the near-surface region differ significantly from those of the bulk polymer.

Developmental defects of the ventromedial hypothalamic nucleus and pituitary gonadotroph in the Ftz‐F1 disrupted mice

Abstract: Ad4BP (or SF-1) has been iden- tified as a transcription factor which regulates all the steroidogenic P450 genes in the peripheral or- gans, and is encoded by the mammalian homo- logue of Drosophila FTZ-F1 gene. mRNA coding for Ad4BP was detected in the hypothalamus and pituitary of rats by RT-PCR. Immunohistochemi- cal analyses using an antiserum to Ad4BP in the brain and pituitary revealed that the transcrip- tion factor is expressed in nuclei of the dorso- medial part of the ventromedial hypothalamus (dmVMH) and in some subpopulation of the ade- nohypophysial cells. Double immunostaining of the pituitary for Ad4BP and trophic peptide hor- mones, FSH, TSH, and ACTH, indicated a re- stricted localization of Ad4BP to the gonadotroph. Disruption of the mouse Ftz-FI gene was clarified to induce severe defects in the organization of the dmVMH and the function of the pituitary gona- dotroph. However, some of the dm VMH neurons and pituitary gonadotrophs persisted, which pro- vided a sharp contrast to complete agenesis of the peripheral steroidogenic tissues (adrenal and go- nads) in the mutant mouse. Additional abnormal- ities were seen in the ventrolateral part of VMH and dorsomedial hypothalamic nucleus, both of which do not express Ad4BP but have strong reciprocal fiber-connections with the dmVMH. Aromatase P450-containing cells in the medial preoptico-amygdaloid region, which were devoid of Ad4BP, persisted even in the brain of the gene disrupted mice. The present results clearly showed that the hypothalamic and pituitary Ad4BPs are essential to normal development of the functional VMH and gonadotroph through some mechanism distinct from that in the periph-

Expression of vascular endothelial growth factor and its possible relation with neovascularization in human brain tumors.

Abstract: To examine which growth factors correlate with neovascularization in human brain tumors, the mRNA levels of transforming growth factor α, transforming growth factor, β, basic fibroblast growth factor, and vascular endothelial growth factor (VEGF) genes were determined by a Northern blot analysis in surgically obtained human gliomas and meninglomas The vascular development was determined by counting the number of microvessels which were immunostained with von Willebrand factor We normalized the growth factor mRNA levels versus the glyceraldehyde phosphate dehydrogenase mRNA level In the 17 gliomas and 16 meningiomas examined, the mRNA of transforming growth factors α and β, basic fibroblast growth factor, and VEGF were expressed at various levels Among those 4 growth factors, the mRNA levels of VEGF, but not those of transforming growth factors α and β and basic fibroblast growth factor, correlated significantly with vascularity in both gliomas (correlation coefficient r = 0499; P < 005) and meningiomas (correlation coefficient r = 0779; P < 0001) These findings thus suggest that VEGF may be a positive factor in tumor angiogenesis in both human gliomas and meningiomas

Functional cooperation of MutT, MutM and MutY proteins in preventing mutations caused by spontaneous oxidation of guanine nucleotide in Escherichia coli

Abstract: 8-Oxo-dGTP (8-oxo-7,8-dihydrodeoxyguanosine triphosphate) is a potent mutagenic substrate for DNA synthesis. The accumulation of 8-oxo-dGTP in the nucleotide pool induces G:C-->T:A transversion as well as A:T-->C:G transversion, and Escherichia coli cells possess mechanisms for preventing such mutations. The mutT gene product specifically hydrolyzes 8-oxo-dGTP to the monophosphate form while the mutM and the mutY gene products function to correct mispairs caused by incorporation of 8-oxoguanine into DNA. From analyses of forward mutations induced in cells lacking 8-oxo-dGTPase (MutT protein) and/or repair enzymes that suppress mutations caused by 8-oxoguanine in DNA (MutM and MutY proteins), cooperative functions of these proteins in control of the spontaneous mutagenesis became evident. In mutator strains lacking MutT and/or MutM proteins, 8-oxoguanine of DNA increased to a concentration expected from the increased rate of mutation.

The internal structure of an active sea-floor massive sulphide deposit

Abstract: THE hydrothermal circulation of sea water through permeable ocean crust results in rock–water interactions that lead to the formation of massive sulphide deposits. These are the modern analogues of many ancient ophiolite-hosted deposits1–4, such as those exposed in Cyprus. Here we report results obtained from drilling a series of holes into an actively forming sulphide deposit on the Mid-Atlantic Ridge. A complex assemblage of sulphide–anhydrite–silica breccias provides striking evidence that such hydrothermal mounds do not grow simply by the accumulation of sulphides on the sea floor. Indeed, the deposit grows largely as an in situ breccia pile, as successive episodes of hydrothermal activity each form new hydrothermal precipitates and cement earlier deposits. During inactive periods, the collapse of sulphide chimneys, dissolution of anhydrite, and disruption by faulting cause brecciation of the deposit. The abundance of anhydrite beneath the present region of focused hydrothermal venting reflects the high temperatures ( > 150 °C) currently maintained within the mound, and implies substantial entrainment of cold sea water into the interior of the deposit. These observations demonstrate the important role of anhydrite in the growth of massive sulphide deposits, despite its absence in those preserved on land.

HLA DRB4 0101-restricted immunodominant T cell autoepitope of pyruvate dehydrogenase complex in primary biliary cirrhosis: evidence of molecular mimicry in human autoimmune diseases.

Abstract: We established six T cell clones specific for pyruvate dehydrogenase complex (PDC)-E2 peptides from four different patients with primary biliary cirrhosis using 33 different peptides of 17-20 amino acid residues corresponding to human PDC-E2 as stimulating antigens. The minimal T cell epitopes of these six T cell clones were all mapped to the same region of the PDC-E2 peptide 163-176 (GDLLAEIETDKATI), which corresponds to the inner lipoyl domain of PDC-E2. The HLA restriction molecules for this epitope were all identified as HLA DRB4 0101. The common essential amino acids of this epitope for these T cell clones were E, D, and K at positions 170, 172, and 173, respectively; other crucial amino acids for this epitope differed in each T cell clone. In addition, the alanine-substituted peptides at positions 170 and 173, but not 172, inhibited the proliferation of all T cell clones induced by the original peptide of human PDC-E2 163-176, indicating that amino acid D at position 172 is a critical MHC-binding site for all T cell clones tested. Interestingly, all T cell clones reacted to PDC-E2 peptide 36-49 (GDLIAEVETDKATV), which corresponds to the outer lipoyl domain of human PDC-E2. Furthermore, one T cell clone cross-reacted with exogenous antigens such as Escherichia coli PDC-E2 peptide 31-44/134-147/235-248 (EQSLITVEGDKASM), which has an EXDK sequence. This is a definite demonstration of the presence of molecular mimicry at the T cell clonal level in human autoimmune diseases. It is also considered possible to design peptide-specific immunotherapy based on the findings of T cell autoepitopes in primary biliary cirrhosis.

The results, indications, and physiology of posteroventral pallidotomy for patients with Parkinson's disease.

Abstract: In the past, stereotactic surgical intervention for Parkinson's disease was considered indicated only in those patients with active motor manifestations that were refractory to pharmacological therapy, manifestations such as tremor, rigidity, dystonia, and dyskinesia. With the reintroduction and refinement of Leksell's posteroventral pallidotomy, both akinetic and hyperkinetic symptoms are now amenable to surgical treatment. We have analyzed the results of 126 patients who underwent either unilateral (n = 58) or bilateral (n = 68) posteroventral pallidotomies. The Unified Parkinson's Disease Rating Scale and Hoehn and Yahr Staging Scale were used for preoperative and postoperative objective assessments. Postoperative follow-up evaluation occurred initially at 1 week and subsequently at intervals between 1 and 12 months (mean = 4.5 months) after surgery. Although individual motor subscores on the Unified Parkinson's Disease Rating Scale were significantly reduced (n = 126, P < or = 0.01), the most dramatic findings were the reversal of akinetic symptoms and the elimination of dyskinesia and profound "off" periods. These clinical results, combined with intraoperative microelectrode records revealing pallidal neuronal hyperactivity, suggest a reconsideration of the pathophysiology of akinesia and point to possible mechanisms of akinesia improvement by posteroventral pallidotomy in some parkinsonian subgroups.

Cytosolic Concentration of Ca2+ Regulates the Plasma Membrane H+-ATPase in Guard Cells of Fava Bean

Abstract: Opening of the stomata is driven by the light-activated plasma membrane proton pumping ATPase, although the activation and inactivation mechanism of the enzyme is not known. In this study, we show that the H+-ATPase in guard cells is reversibly inhibited by Ca2+ at physiological concentrations. Isolated microsomal membranes of guard cell protoplasts from fava bean exhibited vanadate-sensitive, ATP-dependent proton pumping. The activity was inhibited almost completely by 1 [mu]M Ca2+ with a half-inhibitory concentration at 0.3 [mu]M and was restored immediately by the addition of 1,2-bis(2-aminophenoxy)ethane N,N,N[prime],N[prime]-tetraacetic acid, a calcium chelating reagent. Similar reversible inhibition by Ca2+ was shown by the generation of electrical potential in the membranes. Activity of ATP hydrolysis was inhibited similarly by Ca2+ in the same membrane preparations. The addition of 1,2-bis(2-aminophenoxy)ethane N,N,N[prime],N[prime]-tetraacetic acid and EGTA, Ca2+ chelators, to epidermal peels of fava bean induced stomatal opening in the dark, and the opening was suppressed by vanadate. This suggests that the lowered cytosolic Ca2+ activated the proton pump in vivo and that the activated pump elicited stomatal opening. Inhibition of H+-ATPase by Ca2+ may depolarize the membrane potential and could be a key step in the process of stomatal closing through activation of the anion channels. Furthermore, similar inhibition of the proton pumping and ATP hydrolysis by Ca2+ was found in isolated plasma membranes of mesophyll cells of fava bean. These results suggest that Ca2+ regulates the activity of plasma membrane H+-ATPases in higher plant cells, thereby modulating stomatal movement and other cellular processes in plants.

Cellular levels of thioredoxin associated with drug sensitivity to cisplatin, mitomycin C, doxorubicin, and etoposide

Abstract: Thioredoxin, a cellular thiol, functions as a self-defense mechanism in response to environmental stimuli, including oxidative stress. We first determined cellular levels of thioredoxin in several human bladder and prostatic cancer cell lines resistant to cis-diamminedichloroplatinum(II) (cisplatin). All cisplatin-resistant cell lines had much higher levels of thioredoxin than those in their drug-sensitive parental counterpart. We then, by introducing thioredoxin antisense expression plasmids into human bladder cancer T24 cells, established two bladder cancer cell lines that had decreased levels of thioredoxin. These thioredoxin antisense transfectants showed increased sensitivity to cisplatin and also to other superoxide-generating agents, i.e., doxorubicin, mitomycin C, etoposide, and hydrogen peroxide, as well as to UV irradiation, but not to the tubulin-targeting agents, vincristine, and colchicine. Cellular levels of thioredoxin thus appear to limit sensitivity to various superoxide-generating anticancer drugs in cancer cells.