Persistent oxidative stress in cancer

DNA of cancers such as renal cell carcinoma and mammary invasive ductal carcinoma, is persistently exposed to more oxidative stress than that of adjacent normal tissue. We suggest that the concept of 'persistent oxidative stress in cancer' may open up a new research area, explaining part of the characteristic tumor biology of cancer such as activated transcription factors and proto-oncogenes, genomic instability, chemotherapy-resistance, invasion and metastasis.

A precise and fast temperature mapping using water proton chemical shift

A new temperature measurement procedure using phase mapping was developed that makes use of the temperature dependence of the water proton chemical shift. Highly accurate and fast measurements were obtained during phantom and in vivo experiments. In the pure water phantom experiments, an accuracy of more than +/- 0.5 degrees C was obtained within a few seconds/slice using a field echo pulse sequence (TR/TE = 115/13 ms, matrix = 128 x 128, number of slices = 5). The temperature dependence of the water proton chemical shift was found to be almost the same for different materials with a chemical composition similar to living tissues (water, glucide, protein). Using this method, the temperature change inside a cat's brain was obtained with an accuracy of more than +/- 1 degree C and an in-plane resolution of 0.6 x 0.6 mm. The temperature measurement error was affected by several factors in the living system (B0 shifts caused by position shifts of the sample, blood flow, etc.), the position shift effect being the most serious.

A novel octamer binding transcription factor is differentially expressed in mouse embryonic cells

We have identified a novel octamer binding factor (Oct-3) in P19 embryonal carcinoma cells. Oct-3, which recognizes the typical octamer motif (ATTTGCAT) as well as the AT-rich sequence TTAAAATTCA, is present in P19 stem cells but disappears when the cells are induced to differentiate by retinoic acid (RA). Cloned cDNA corresponding to Oct-3 encodes a protein of 377 amino acids. Oct-3 has a conserved POU domain, but the remaining part is distinct from other POU domain-containing proteins such as Oct-1 and Oct-2. mRNA of 1.5 kb coding for Oct-3 is abundant in P19 stem cells but is dramatically repressed during RA-induced differentiation. Repression of the 1.5 kb mRNA is rapid and specific to RA. In mouse, oct-3 mRNA is undetectable in all the adult organs examined. The N-terminal proline-rich region of Oct-3, when fused to the DNA binding domain of c-Jun, functions as a transcriptional activating domain. We suggest that Oct-3 is a novel octamer binding transcription factor that is developmentally regulated during mouse embryogenesis.

Crystal structures of bovine milk xanthine dehydrogenase and xanthine oxidase: structure-based mechanism of conversion

Mammalian xanthine oxidoreductases, which catalyze the last two steps in the formation of urate, are synthesized as the dehydrogenase form xanthine dehydrogenase (XDH) but can be readily converted to the oxidase form xanthine oxidase (XO) by oxidation of sulfhydryl residues or by proteolysis. Here, we present the crystal structure of the dimeric (M(r), 290,000) bovine milk XDH at 2.1-A resolution and XO at 2.5-A resolution and describe the major changes that occur on the proteolytic transformation of XDH to the XO form. Each molecule is composed of an N-terminal 20-kDa domain containing two iron sulfur centers, a central 40-kDa flavin adenine dinucleotide domain, and a C-terminal 85-kDa molybdopterin-binding domain with the four redox centers aligned in an almost linear fashion. Cleavage of surface-exposed loops of XDH causes major structural rearrangement of another loop close to the flavin ring (Gln 423Lys 433). This movement partially blocks access of the NAD substrate to the flavin adenine dinucleotide cofactor and changes the electrostatic environment of the active site, reflecting the switch of substrate specificity observed for the two forms of this enzyme.

Doxorubicin-loaded poly(ethylene glycol)-poly(beta-benzyl-L-aspartate) copolymer micelles: their pharmaceutical characteristics and biological significance

Doxorubicin (DOX) was physically loaded into micelles prepared from poly(ethylene glycol)-poly(beta-benzyl-L-aspartate) block copolymer (PEG-PBLA) by an o/w emulsion method with a substantial drug loading level (15 to 20 w/w%). DOX-loaded micelles were narrowly distributed in size with diameters of approximately 50-70 nm. Dimer derivatives of DOX as well as DOX itself were revealed to be entrapped in the micelle, the former seems to improve micelle stability due to its low water solubility and possible interaction with benzyl residues of PBLA segments through pi-pi stacking. Release of DOX compounds from the micelles proceeded in two stages: an initial rapid release was followed by a stage of slow and long-lasting release of DOX. Acceleration of DOX release can be obtained by lowering the surrounding pH from 7.4 to 5.0, suggesting a pH-sensitive release of DOX from the micelles. A remarkable improvement in blood circulation of DOX was achieved by use of PEG-PBLA micelle as a carrier presumably due to the reduced reticuloendothelial system uptake of the micelles through a steric stabilization mechanism. Finally, DOX loaded in the micelle showed a considerably higher antitumor activity compared to free DOX against mouse C26 tumor by i.v. injection, indicating a promising feature for PEG-PBLA micelle as a long-circulating carrier system useful in modulated drug delivery.

Signal transduction in hypoxic cells: inducible nuclear translocation and recruitment of the CBP/p300 coactivator by the hypoxia-inducible factor-1alpha

In response to decreased cellular oxygen concentrations the basic helix-loop-helix (bHLH)/PAS (Per, Arnt, Sim) hypoxia-inducible transcription factor, HIF-1alpha, mediates activation of networks of target genes involved in angiogenesis, erythropoiesis and glycolysis. Here we demonstrate that the mechanism of activation of HIF-1alpha is a multi-step process which includes hypoxia-dependent nuclear import and activation (derepression) of the transactivation domain, resulting in recruitment of the CREB-binding protein (CBP)/p300 coactivator. Inducible nuclear accumulation was shown to be dependent on a nuclear localization signal (NLS) within the C-terminal end of HIF-1alpha which also harbors the hypoxia-inducible transactivation domain. Nuclear import of HIF-1alpha was inhibited by either deletion or a single amino acid substitution within the NLS sequence motif and, within the context of the full-length protein, these mutations also resulted in inhibition of the transactivation activity of HIF-1alpha and recruitment of CBP. However, nuclear localization per se was not sufficient for transcriptional activation, since fusion of HIF-1alpha to the heterologous GAL4 DNA-binding domain generated a protein which showed constitutive nuclear localization but required hypoxic stimuli for function as a CBP-dependent transcription factor. Thus, hypoxia-inducible nuclear import and transactivation by recruitment of CBP can be functionally separated from one another and play critical roles in signal transduction by HIF-1alpha.

Development of the polymer micelle carrier system for doxorubicin

We show the result of pre-clinical study of NK911, a polymeric micelle carrier system for doxorubicin (DOX). The NK911 micelle carrier consists of polyethyleneglycol and conjugated doxorubicin-polyaspartic acid. It has high hydrophobic inner core, and therefore can entrap the sufficient amount of DOX. NK911 has a small particle size of about 40 nm in diameter that accumulates in tumor tissue by EPR effect showing much stronger activity than the free DOX. We plan to perform a clinical trial at National Cancer Center Hospital, Japan from 2001.

Human cathepsin O2, a matrix protein-degrading cysteine protease expressed in osteoclasts. Functional expression of human cathepsin O2 in Spodoptera frugiperda and characterization of the enzyme

Cathepsin O2, a human cysteine protease predominantly present in osteoclasts, has been functionally expressed in Spodoptera frugiperda Sf9 cells using the Autographa californica nuclear polyhedrosis virus. Following in vitro activation at pH 4.0 with pepsin, active enzyme with an apparent molecular weight of 29,000 was obtained. N-terminal sequencing revealed the typical processing site for cysteine proteases of the papain family with a proline in the position adjacent to the N-terminal alanine residue. The S2P2 subsite specificity of human cathepsin O2 is similar to cathepsin S but distinguished from cathepsins L and B. Similar to cathepsin S, cathepsin O2 is characterized by a bellshaped pH activity profile and is stable at pH 6.5 for 30 min at 37 degrees C. Cathepsin O2 is further distinguished by its potent collagenolytic activity against Type I collagen between pH 5 and 6, and elastinolytic activity against insoluble elastin at pH 7.9. Its capacity to efficiently degrade Type I collagen and its high expression in osteoclasts suggest that cathepsin O2 may play a major role in human osteoclastic bone resorption.

Cyclin G is a transcriptional target of the p53 tumor suppressor protein

Through a PCR-based differential screening method, cyclin G was identified as a novel transcriptional target of the p53 tumor suppressor gene product. In both a mouse p53 temperature-sensitive leukemic cell line and mouse embryonic fibroblasts (MEF) after gamma-irradiation, cyclin G mRNA was rapidly induced. MEF from a p53-deficient mouse expressed cyclin G at a level > 10-fold lower than that from a wild-type mouse. Using a DNA binding assay, a specific p53 binding site was identified upstream from the cyclin G gene, which functioned as a p53-dependent cis-acting element in a transient transfection assay. These results suggest that cyclin G might participate in a p53-mediated pathway to prevent tumorigenesis.

Redox-regulated recruitment of the transcriptional coactivators CREB-binding protein and SRC-1 to hypoxia-inducible factor 1alpha

Hypoxia-inducible factor 1alpha (HIF-1alpha) functions as a transcription factor that is activated by decreased cellular oxygen concentrations to induce expression of a network of genes involved in angiogenesis, erythropoiesis, and glucose homeostasis. Here we demonstrate that two members of the SRC-1/p160 family of transcriptional coactivators harboring histone acetyltransferase activity, SRC-1 and transcription intermediary factor 2 (TIF2), are able to interact with HIF-1alpha and enhance its transactivation potential in a hypoxia-dependent manner. HIF-1alpha contains within its C terminus two transactivation domains. The hypoxia-inducible activity of both these domains was enhanced by either SRC-1 or the CREB-binding protein (CBP)/p300 coactivator. Moreover, at limiting concentrations, SRC-1 produced this effect in synergy with CBP. Interestingly, this effect was strongly potentiated by the redox regulatory protein Ref-1, a dual-function protein harboring DNA repair endonuclease and cysteine reducing activities. These data indicate that all three proteins, CBP, SRC-1, and Ref-1, are important components of the hypoxia signaling pathway and have a common function in regulation of HIF-1alpha function in hypoxic cells. Given the absence of cysteine residues in one of the Ref-1-regulated transactivation domains of HIF-1alpha, it is thus possible that Ref-1 functions in hypoxic cells by targeting critical steps in the recruitment of the CBP-SRC-1 coactivator complex.

Genetic analyses of proteolysis, hemoglobin binding, and hemagglutination of Porphyromonas gingivalis. Construction of mutants with a combination of rgpA, rgpB, kgp, and hagA

Porphyromonas gingivalis produces arginine-specific cysteine proteinase (Arg-gingipain, RGP) and lysine-specific cysteine proteinase (Lys-gingipain, KGP) in the extracellular and cell-associated forms. Two separate genes (rgpA and rgpB) and a single gene (kgp) have been found to encode RGP and KGP, respectively. We constructed rgpA rgpB kgp triple mutants by homologous recombination with cloned rgp and kgp DNA interrupted by drug resistance gene markers. The triple mutants showed no RGP or KGP activity in either cell extracts or culture supernatants. The culture supernatants of the triple mutants grown in a rich medium had no proteolytic activity toward bovine serum albumin or gelatin derived from human type I collagen. Moreover, the mutants did not grow in a defined medium containing bovine serum albumin as the sole carbon/energy source. These results indicate that the proteolytic activity of P. gingivalis toward bovine serum albumin and gelatin derived from human type I collagen appears to be attributable to RGP and KGP. The hemagglutinin gene hagA of P. gingivalis possesses the adhesin domain regions responsible for hemagglutination and hemoglobin binding that are also located in the C-terminal regions of rgpA and kgp. A rgpA kgp hagA triple mutant constructed in this study exhibited no hemagglutination using sheep erythrocytes or hemoglobin binding activity, as determined by a solid-phase binding assay with horseradish peroxidase-conjugated human hemoglobin, indicating that the adhesin domains seem to be particularly important for P. gingivalis cells to agglutinate erythrocytes and bind hemoglobin, leading to heme acquisition.

Formation of 4-hydroxy-2-nonenal-modified proteins in the renal proximal tubules of rats treated with a renal carcinogen, ferric nitrilotriacetate

An iron chelate, ferric nitrilotriacetate (Fe-NTA), induces proximal tubular necrosis, a consequence of lipid peroxidation, that finally leads to a high incidence of renal adenocarcinoma in rodents. Lipid peroxidation as monitored by formation of thiobarbituric acid-reactive substances and free 4-hydroxy-2-nonenal (HNE) was observed in the kidney homogenates of rats treated with Fe-NTA. Based on the fact that HNE is capable of reacting with cellular proteins, we attempted to detect the localization of HNE-modified proteins in rat kidney tissues with an immunohistochemical procedure. By means of an immunohistochemical technique using polyclonal antibody against the HNE-modified proteins, it was shown that HNE-modified proteins are formed in the target cells of this carcinogenesis model. HNE-modified proteins were detected in the renal proximal tubules 1 hr after i.p. administration of Fe-NTA (15 mg of iron per kg). Intense positivity was found in the cells with degeneration. After 6 hr, the level of HNE-protein conjugates decreased due to the subsequent necrosis. The intensity of the immunochemical reaction with HNE-modified proteins increased in parallel with an increase in the amounts of thiobartituric acid-reactive substances and free HNE that were found. Furthermore, histochemical detection of aldehydes by cold Schiff's reagent demonstrated that location of aldehydes was identical to that of the HNE-modified proteins determined by immunohistochemical procedures. It would thus appear that the production of HNE, a genotoxic and mutagenic aldehyde, and its reaction with proteins may play a role in Fe-NTA-induced renal carcinogenesis.

Inhibition of 4-nitroquinoline-1-oxide-induced rat tongue carcinogenesis by the naturally occurring plant phenolics caffeic, ellagic, chlorogenic and ferulic acids

The modifying effects of dietary administration of the plant phenolic antioxidants caffeic acid (CA), ellagic acid (EA), chlorogenic acid (CGA) and ferulic acid (FA) during the initiation phase on 4-nitroquinoline-1-oxide (4-NQO)-induced tongue carcinogenesis and on the number and area of silver-stained nucleolar organizer region proteins (AgNORs), a new cell proliferation marker, of the tongue squamous epithelium were investigated in male F344 rats. Rats were fed the diet containing 500 p.p.m. CA, 400 p.p.m. EA, 250 p.p.m. CGA or 500 p.p.m. FA for 7 weeks. One week after the commencement of the diets, 4-NQO (20 p.p.m.) was administered in the drinking water for 5 weeks. Feeding of four phenolic compounds significantly reduced the incidences of tongue neoplasms (squamous cell papilloma and carcinoma) and preneoplastic lesions (hyperplasia and dysplasia) by 32 weeks, and rats fed CA or EA had no tongue neoplasms. The number and area of AgNORs per nucleus were decreased significantly by dietary treatment with these four phenolics. Thus, CA, EA, CGA and FA inhibited the tongue carcinogenesis induced by 4-NQO when they were administered concurrently with the carcinogen. These results might suggest possible application of these natural substances for cancer chemoprevention in tongue in addition to other tissues (skin, lung, liver and esophagus).

Longitudinal study of cerebrospinal fluid levels of tau, A beta1-40, and A beta1-42(43) in Alzheimer's disease: a study in Japan

To clarify the alterations of tau, amyloid beta protein (A beta) 1-40 and A beta1-42(43) in the cerebrospinal fluid (CSF) that accompany normal aging and the progression of Alzheimer's disease (AD), CSF samples of 93 AD patients, 32 longitudinal subjects among these 93 AD patients, 33 patients with non-AD dementia, 56 with other neurological diseases, and 54 normal control subjects from three independent institutes were analyzed by sensitive enzyme-linked immunosorbent assays. Although the tau levels increased with aging, a significant elevation of tau and a correlation between the tau levels and the clinical progression were observed in the AD patients. A significant decrease of the A beta1-42(43) levels and a significant increase of the ratio of A beta1-40 to A beta1-42(43) were observed in the AD patients. The longitudinal AD study showed continuous low A beta1-42(43) levels and an increase of the ratio of A beta1-40 to A beta1-42(43) before the onset of AD. These findings suggest that CSF tau may increase with the clinical progression of dementia and that the alteration of the CSF level of A beta1-42(43) and the ratio of A beta1-40 to A beta1-42(43) may start at early stages in AD. The assays of CSF tau, A beta1-40, and A beta1-42(43) provided efficient diagnostic sensitivity (71%) and specificity (83%) by using the production of tau levels and the ratio of A beta1-40 to A beta1-42(43), and an improvement in sensitivity (to 91%) was obtained in the longitudinal evaluation.

Novel diagnostic value of circulating miR-18a in plasma of patients with pancreatic cancer

BACKGROUND

Several recent studies have demonstrated that microRNAs (miRNAs) are stably detectable in the plasma/serum. We hypothesised that miR-18a in the plasma is a potential biomarker in patients with pancreatic cancer.

METHODS

miR-18a is located in the miR-17-92 cluster and reported to be highly expressed in pancreatic cancer tissues. This study was divided into three parts: (1) Confirmation of higher miR-18a levels in primary pancreatic cancer tissues and cell lines than in normal pancreatic tissues and a human fibroblast cell line. (2) Evaluation of the plasma miR-18a assay using quantitative RT-PCR by comparing plasma results obtained from 36 patients with pancreatic cancer and from 30 healthy volunteers. (3) Evaluation of the assay for monitoring tumour dynamics in patients with pancreatic cancer.

RESULTS

(1) The expression of miR-18a was significantly higher in pancreatic cancer tissues (P=0.012) and pancreatic cancer cell lines (P=0.015) than in normal tissues and fibroblasts. (2) Plasma concentrations of miR-18a were significantly higher in pancreatic cancer patients than in controls (P<0.0001). The value of the area under the receiver-operating characteristic curve (AUC) was 0.9369. (3) Plasma levels of miR-18a were significantly lower in postoperative samples than in preoperative samples (P=0.0077).

CONCLUSION

Circulating miR-18a might provide new complementary tumour markers for pancreatic cancer.

Characterization of physical entrapment and chemical conjugation of adriamycin in polymeric micelles and their design for in vivo delivery to a solid tumor

An anticancer drug adriamycin (ADR) was incorporated into polymeric micelles forming from poly(ethylene glycol)-poly(aspartic acid) block copolymer by chemical conjugation and physical entrapment. Structural stability of the polymeric micelles was found to be dependent on both the contents of chemically conjugated and physically entrapped ADR. The polymeric micelle with high contents of the chemically conjugated ADR and the physically entrapped ADR expressed very high in vivo antitumor activity against murine C 26 tumor, while the polymeric micelle with only the chemically conjugated ADR showed negligible in vivo activity. This indicates that the physically entrapped ADR played a major role in antitumor activity in vivo. For the polymeric micelle with the high ADR contents, it was found that a dimer of adriamycin molecules formed and that this dimer was physically entrapped in the inner core of the micelle as well as intact ADR.

Circulating microRNAs in plasma of patients with oesophageal squamous cell carcinoma

BACKGROUND

Several recent studies demonstrated that microRNAs (miRNAs) are stably detectable in plasma/serum. We hypothesised that plasma miRNAs concentrations contributed to potential biomarkers in patients with oesophageal squamous cell carcinoma (ESCC).

METHODS

We selected three oncogenic miRNAs (miR-21, miR-184, miR-221) and one tumour suppressive miRNA (miR-375), which are frequently reported in squamous cell carcinoma, as candidate targets for this plasma miRNA assay. This study was divided into three steps: (1) Determination of appropriate plasma miRNAs in preliminary tests. (2) Evaluation of whether the plasma miRNA assays could monitor tumour dynamics. (3) Validation study on the clinical application of plasma miRNA assays in 50 ESCC patients and 20 healthy volunteers.

RESULTS

(1) In preliminary tests, the plasma level of miR-21 was significantly higher (P=0.0218) and that of miR-375 (P=0.0052) was significantly lower in ESCC patients than controls. (2) The high plasma miR-21 levels reflected tumour levels in all cases (100%). The plasma level of miR-21 was significantly reduced in postoperative samples (P=0.0058). (3) On validation analysis, the plasma level of miR-21 tended to be higher in ESCC patients (P=0.0649), while that of miR-375 was significantly lower (P<0.0001) and the miR-21/miR-375 ratio was significantly higher (P<0.0001) in ESCC patients than in controls. The value of the area under the receiver-operating characteristic curve (AUC) was 0.816 for the miR-21/miR-375 ratio assay. Patients with a high plasma level of miR-21 tended to have greater vascular invasion (P=0.1554) and to show a high correlation with recurrence (P=0.0164).

CONCLUSION

Detection of circulating miRNAs might provide new complementary tumour markers for ESCC.

Testicular germ cell tumours

Testicular germ cell tumours are at the crossroads of developmental and neoplastic processes. Their cause has not been fully elucidated but differences in incidences suggest that a combination of genetic and environment factors are involved, with environmental factors predominating early in life. Substantial progress has been made in understanding genetic susceptibility in the past 5 years on the basis of the results of large genome-wide association studies. Testicular germ cell tumours are highly sensitive to radiotherapy and chemotherapy and hence have among the best outcomes of all tumours. Because the tumours occur mainly in young men, preservation of reproductive function, quality of life after treatment, and late effects are crucial concerns. In this Seminar, we provide an overview of advances in the understanding of the epidemiology, genetics, and biology of testicular germ cell tumours. We also summarise the consensus on how to treat testicular germ cell tumours and focus on a few controversies and improvements in the understanding of late effects of treatment and quality of life for survivors.

Construction and characterization of arginine-specific cysteine proteinase (Arg-gingipain)-deficient mutants of Porphyromonas gingivalis. Evidence for significant contribution of Arg-gingipain to virulence

Arginine-specific cysteine proteinase (Arg-gingipain; formerly, argingipain) is one of the major extracellular proteinases produced by the oral anaerobic bacterium Porphyromonas gingivalis. To determine whether Arg-gingipain is important for periodontopathogenicity of the organism, Arg-gingipain-deficient mutants were constructed via gene disruption by use of suicide plasmid systems. First, Southern hybridization analyses suggested that two separate Arg-gingipain-encoding genes designated rgpA and rgpB existed on 12.5- and 7.8-kilobase pair HindIII chromosomal fragments of P. gingivalis ATCC33277, respectively. rgpA and rgpB single mutants were constructed by mobilization of a suicide plasmid. Then, an rgpA rgpB double mutant was isolated by electroporation with a second suicide plasmid. No proteolytic activity for Arg-gingipain was observed in either the cell extract or the culture supernatant of the rgpA rgpB mutant. The chemiluminescence response of polymorphonuclear leukocytes, which is closely related to their bactericidal function, was not inhibited by the culture supernatant of the rgpA rgpA mutant, while the wild type parent showed a significant inhibition of the response. The result suggests that Arg-gingipain is responsible for disruption of the function of polymorphonuclear leukocytes. In addition, the rgpA rgpB double mutations caused a marked decrease in the hemagglutination of P. gingivalis, indicating that a major part of the hemagglutinin activity of the organism is associated with the two genes. These findings demonstrate that Arg-gingipain makes a significant contribution to the virulence of P. gingivalis.

Radial glia is a progenitor of neocortical neurons in the developing cerebral cortex

Neocortical neurons are produced by cell division of neural stem cells in the ventricular zone of the cerebral cortex. We investigated the production of neurons by infecting neuroepithelial cells with a modified GFP-recombinant adenovirus. The adenovirus DNA is inherited by only one daughter cell at each cell division and travels one way from the progenitor to the progeny. Since the ventricular zone (VZ) of the embryo neocortex expressed an adenovirus receptor, CAR ubiquitously, morphology and cell-lineage of cells in the VZ could be revealed by the adenovirus infection. Radial glias, cells with a bipolar shape, and spherical cells were found as modified-GFP-positive (mGFP+) in the VZ. The bipolar cells (radial cells) had a radial process not in contact with the pia mater and a growth-cone-like structure at the edge of their radial process, while the radial glias had a process spanning all the cortical layers. Ten hours after viral infection, most mGFP+ cells were radial cells. In the following 8 h, the percentage of mGFP+ radial glias in mGFP+ neocortical cells increased from 18 to 50%, while that in radial/spherical cells decreased from 75 to 19%. The radial glias often divided asymmetrically and produced spherical cells and neuronal precursors. The spherical cells seemed to become radial cells by extending a radial process. The spherical cells, radial cells and radial glias seemed to constitute a proliferating cell cycle during which postmitotic neuronal precursors are produced. The neuronal precursors that inherited the radial processes migrated radially and developed into neocortical neurons. Four days after the viral infection, 97% of mGFP+ cells were neocortical neurons. Here, we propose that the radial glia is a progenitor of neocortical neurons, and that a significant number of radially migrating neurons is guided by their own radial processes connected to the pia mater.

Human cathepsin O2, a novel cysteine protease highly expressed in osteoclastomas and ovary molecular cloning, sequencing and tissue distribution

A 1.6-kilobase full-length cDNA of a novel human cysteine protease has been isolated and sequenced. The nucleotide sequence encodes a polypeptide of 329 amino acids composed of a 15-residue N-terminal signal peptide, a 99-residue propeptide, and a mature protein of 215 amino acids. The deduced amino acid sequence contains two potential N-glycosylation sites, one located in the proregion and one in the mature enzyme. Comparison of the amino acid sequence of cathepsin O2 with that of known human lysosomal cysteine proteases revealed a substantial degree of similarity to cathepsins L and S. Northern blot analysis indicates predominant levels of expression in osteoclastomas and ovary and therefore the enzyme was named cathepsin O2. The extremely high expression levels of human cathepsin O2 in osteoclastomas suggest a major role of this novel enzyme in bone remodelling and bone related diseases.

Selective delivery of adriamycin to a solid tumor using a polymeric micelle carrier system

The anticancer drug, adriamycin (ADR), was incorporated by physical entrapment into polymeric micelles for selective delivery to a murine solid tumor colon adenocarcinoma 26 (C 26). In vivo antitumor activity of ADR was greatly enhanced by this incorporation into polymeric micelles. Using one polymeric micelle delivery system, the tumor completely disappeared at two doses, while free ADR exhibited a fair inhibition effect on tumor growth only at the maximum tolerated dose. Biodistribution analysis revealed that the physically entrapped micellar ADR accumulated at tumor sites in a highly selective manner. These results indicate that these polymeric micelles are a promising system for delivering hydrophobic anticancer drugs selectively to solid tumor sites using a passive targeting mechanism.

Phosphorylation of alphaB-crystallin in response to various types of stress

Phosphorylation of alphaB-crystallin, a member of the hsp27 family, in human glioma (U373 MG) cells was stimulated by exposure of the cells to various stimuli, which included heat, arsenite, phorbol 12-myristate 13-acetate (PMA), okadaic acid, H2O2, anisomycin, and high concentrations of NaCl or sorbitol, but not in response to agents that elevated intracellular levels of cyclic AMP. Cells exposed to PMA together with okadaic acid yielded three bands of 32P-labeled alphaB-crystallin when immunoprecipitated samples were subjected to electrophoresis on an isoelectric focusing gel. All of the phosphorylated residues were identified as serine, an indication that three different serine residues can act as sites of phosphorylation in alphaB-crystallin. Structural analysis by mass spectrometry revealed that phosphorylation of alphaB-crystallin occurred at serines 19, 45, and 59. Dithiothreitol and staurosporine selectively inhibited the phosphorylation induced by arsenite and the phorbol ester, respectively. SB202190, an inhibitor of p38 mitogen-activated protein (MAP) kinase, suppressed the phosphorylation induced by arsenite, anisomycin, H2O2, sorbitol, NaCl, and heat shock, but not that induced by PMA and okadaic acid. The PMA-induced phosphorylation was selectively suppressed by an inhibitor of p44 MAP kinase kinase, PD98059. Although PMA and arsenite preferentially stimulated the phosphorylation of Ser-45 and Ser-59, respectively, as determined with antibodies that recognized the respective phosphorylated forms of alphaB-crystallin, all three sites were phosphorylated in response to each stimulus. These results suggest that p38 MAP kinase or p44 MAP kinase might be involved in the signal transduction cascade that leads to the phosphorylation of alphaB-crystallin. The phosphorylation of alphaB-crystallin was also enhanced in the heart and diaphragm when rats were exposed to heat stress (42 degrees C for 20 min).