Distribution of u.v.-induced repair events in higher-order chromatin loops in human and hamster fibroblasts

The repair of u. v.-induced damage in human and rodent cellswas investigated at the level of DNA loops attached to the nuclearmatrix. After 2 h post-u.v. incubation, DNase I digestion studiesrevealed a 3- to 4-fold enrichment of repair-labeled DNA atthe nuclear matrix in four xeroderma pigmen-tosum cell strainsbelonging to complementation group C. This non-random distributionwas not affected by treatment with sodium butyrate. In othercells with limited excision repair, i.e. two xeroderma pigmentosumcell strains of complementation group D and Syrian hamster embryoniccells, as well as in HeLa cells and normal human fibroblasts,no enrichment of repair-labeled DNA at the nuclear matrix wasobserved. Visualization of repair events in DNA loops by auto-radiographyof DNA halo-matrix structures confirmed the biochemical observations.The presence or absence of preferential repair of nuclear matrix-associatedDNA paralleled the presence or absence of inhomogeneity in thedistribution of T4 endonuclease-V-sensitive sites. A detailedanalysis of repair events in xeroderma pigmentosum cells ofcomplementation group C showed that after 2 h post-u.v. incubation,repair events were found at both attachment sites in a limitednumber of loops and that large domains of loops were not subjectedto repair.     

Plasma membrane-mediated nuclear uptake and chromatin binding of insulin in tumor cell lines

Analysis of different cellular fractions after incubation of SW 948 and SW 707 colorectal carcinoma cells or WM 266-4 melanoma cells with 125I-insulin revealed the nondegraded hormone in the chromatin of these cells. Nuclear 125I-insulin was bound to specific fragments of EcoRI-, HaeIII-, and HincII-digested chromatin. A 45-kDa chromatin protein species that binds 125I-insulin was identified. Actinomycin D and cycloheximide inhibited the insulin-stimulated expression of chromatin receptors. Uptake of 125I-insulin by isolated nuclei occurred only in the presence of plasma membranes. Thus, at least some effects of insulin on target cells can be explained by direct gene regulation instead of "second messenger" action.     

Preferential binding of the carcinogen benzo[a]pyrene to DNA in active chromatin and the nuclear matrix

Rat liver nuclei or hepatocytes were incubated with the proximatecarcinogen, benzo[a]pyrene (BP) and its ultimate carcinogen,anti-benzo[a]pyrene-7, 8-dol-9,10-epoxide (BPDE. Following carcinogenexposure, nuclei were fractionated by micrococcal nuclease digestionand stepwise extraction to yield an active chromatin fractionenriched in transcribed versus non-transcribed genes, a bulkchromatin fraction, a high-salt-extracted chromatin fractionand a nuclear matrix fraction containing elevated concentrationsof transcribed and non-transcribed genes. BP binds more readilyto DNA of active chromatin and nuclear matrix than to bulk chromatin.Since low concentrations of BPDE also selectively damage activechromatin and matrix DNA, selectivity is not due to the sub-nuclearlocation of enzymes which activate BP to BPDE. Higher BPDE concentrationscause more uniform DNA damage. Selective carcinogen attack mayresult from an accessible DNA conformation in active chromatinand matrix or from partitioning of carcinogen in the nuclearmembrane.     

Cytological features of small cell lung cancer--relation between nuclear chromatin change and chemotherapeutic effect

This paper describes the relation between the cytologic features, change of chromatin and effect of chemotherapy in 75 cases of small cell lung cancer. Basing on the microscopic changes of the chromatin in the cancer cells, 4 types were observed: (1) chromatin evenly distributed with fine granules (2) chromatin evenly distributed with rough granules (3) chromatin sparsely distributed with rough granules (4) ink spot-like nuclei. Type 1 was found in 75.7% of the responders to chemotherapy while Type 3 was frequently observed in 69.2% of the non-responders. The results suggest that the changes of nuclear chromatin be used as an index to predict the response to chemotherapy, conforming to Takeshi's observation. Yet, in this series, the exfoliative cells were obtained from the sputum rather than Takeshi's brush during bronchoscopy. The authors believe that the changes of chromatin may be observed clearly if the sputum is fresh, smeared promptly and stained in the standard way.     

Nasal mucociliary clearance in health and disease

“Standard saccharine test is used to detect nasal mucociliary clearance time in healthy individuals both adults and children. The length of the nose was measured radiologically and with the help of a soft malleable rubber catheter. For healthy individuals, mean nasal mucociliary clearance lime is 8.2 minutes in children and 9.5 minutes in adults. The mean nasal mucociliary clearance rates were 11.1 mm/min for children and 12.7 mm/min for adults. Deviated nasal septum, chronic sinusitis, allergic rhinitis, atrophic rhinitis, chronic smokers and patients with recent nasal packings were taken as diseased conditions in adults, whereas children with adenoid hyperplasia were taken for the study. In all of these, nasal mucociliary clearance was significantly prolonged.”     

MRP2 and 3 in health and disease

MRPs are membrane proteins transporting organic anions at the expense of ATP hydrolysis. MRP2 is known to be a major transporter of organic anions from the liver into bile. We discuss recent results showing allosteric control of human but not rat MRP2. MRP3 has been considered a major player in bile salt metabolism, but our recent results with Mrp3 KO mice do not support this. Instead, we have found a role for MRP3 in the cellular export of drug-glucuronide conjugates. We discuss problems in extrapolating results obtained for murine MRPs.     

P53 nuclear overexpression and disease progression in ta-bladder carcinoma

This study investigates the prevalence and clinical relevance of nuclear overexpression of the p53 protein, as detected by antibody PAb1801, in 54 patients with pathologically confirmed Ta bladder carcinomas obtained by transurethral resection at Memorial Sloan-Kettering Cancer Center between 1972 and 1980. No patient received any prior adjuvant therapy. Clinical and histopathological prognostic variables such as age, sex and tumor grade were also analyzed. The median follow-up was 110 months. Patients were stratified into two groups according to the percent of tumor cells with nuclear overexpression of the p53 protein. Group A included carcinomas with less than 20% (n=42) and Group B with 20% or more (n=12) of tumor cells with positive nuclear immunoreactivity. Five patients of Group A (12%) developed tumor progression as did 7 (58%) patients of Group B (p=0.002). Three (7%) patients of Group A and 3 (25%) patients of Group B died of bladder cancer (p=0.12). This study demonstrates a relatively low prevalence of altered p53 expression in this early stage of bladder cancer (22%). Nuclear overexpression of the p53 protein in greater-than-or-equal-to 20% tumor cells,was highly associated with tumor grade (p=0.01), but the former was the only independent marker of tumor progression (p=0.0008) on the basis of the multivariate analysis performed. It was also the only independent variable . associated with death due to bladder cancer (p=0.04). We conclude that p53 nuclear overexpression is a prognostic indicator in this disease, and may be useful for selection of therapy for patients with non-invasive papillary superficial bladder carcinoma.     

Molecular mechanisms of lymphangiogenesis in health and disease

Studies of the last decades have revealed the importance of angiogenesis for normal growth and for the pathogenesis of numerous diseases. Much less studied is lymphangiogenesis, the growth of lymphatic vessels, which drain extravasated fluid, proteins, and cells and transport them back to the venous circulation. Nonetheless, insufficient lymphangiogenesis causes incapacitating lymphedema, while lymphatic growth around tumors may facilitate metastatic spread of malignant cells that ultimately kill the patient. The recent discovery of the key lymphangiogenic factors VEGF-C and VEGF-D and their receptor VEGFR-3 has allowed novel insights into how the lymphatic vessels and blood vessels coordinately grow and affect human disease. In addition, these studies have opened novel diagnostic and therapeutic avenues for the treatment of lymphedema and metastasis. This overview highlights the recent insights and developments in the field of lymphatic vascular research.     

C1GALT1 in health and disease

O-linked glycosylation (O-glycosylation) and N-linked glycosylation (N-glycosylation) are the two most important forms of protein glycosylation, which is an important post-translational modification. The regulation of protein function involves numerous mechanisms, among which protein glycosylation is one of the most important. Core 1 synthase glycoprotein-N-acetylgalactosamine 3-β-galactosyltransferase 1 (C1GALT1) serves an important role in the regulation of O-glycosylation and is an essential enzyme for synthesizing the core 1 structure of mucin-type O-glycans. Furthermore, C1GALT1 serves a vital role in a number of biological functions, such as angiogenesis, platelet production and kidney development. Impaired C1GALT1 expression activity has been associated with different types of human diseases, including inflammatory or immune-mediated diseases, and cancer. O-glycosylation exists in normal tissues, as well as in tumor tissues. Previous studies have revealed that changes in the level of glycosyltransferase in different types of cancer may be used as potential therapeutic targets. Currently, numerous studies have reported the dual role of C1GALT1 in tumors (carcinogenesis and cancer suppression). The present review reports the role of C1GALT1 in normal development and human diseases. Since the mechanism and regulation of C1GALT1 and O-glycosylation remain elusive, further studies are required to elucidate their effects on development and disease.     

Nickel-bound chromatin, nucleic acids, and nuclear proteins from kidney and liver of rats treated with nickel carbonate in vivo

The in vivo binding of nickel to chromatin, nucleic acids, and nuclear proteins from rat kidney and liver was investigated. Evidence is presented for the direct interaction of nickel with chromatin from rat tissues following i.p. injection of nickel carbonate. A gentle DNA isolation procedure was developed and used to isolate nickel-bound whole chromatin, DNA + histone octamer complex (polynucleosomes), and deproteinized DNA from kidney and liver nuclei. A similar procedure was developed for isolating nickel-bound RNA from the cytoplasm. The level of nickel bound to whole chromatin from kidney was higher than that from liver, and these levels could be related to the nuclear concentration of nickel. Much higher levels of nickel were bound to the DNA + histone octamer complex and purified, deproteinized DNA from kidney as compared to liver. Substantial levels of nickel were bound to nonhistone proteins and/or chromatin-associated RNA from kidney and liver nuclei. Nickel was also associated with histone octamer proteins from kidney; however, little or no nickel was associated with histone octamer proteins from liver. 63Ni binding to nuclear proteins in rats given injections of 63Ni(II) was investigated by using two different gel electrophoretic systems. Electrophoretic conditions in both systems were found to remove protein-bound 63Ni. These results are discussed relative to the molecular mechanism of nickel carcinogenesis.     

Analysis of biological and biochemical parameters for chromatin and nuclear matrix association of SV40 large T antigen in transformed cells

We analysed biological and biochemical parameters for the association of the simian virus 40 (SV40) large tumor antigen (large T) with the cellular chromatin and the nuclear matrix in SV40-transformed cells. Nuclear subclasses of large T were isolated by in situ cell fractionation (Staufenbiel & Deppert, 1983) and first analysed for possible biological functions in the maintenance of cellular transformation. Like large T in SV40 wild-type transformants, large T in SV40 tsA mutant (tsA58)-transformed cells, expressing a temperature-dependent phenotype, was present in all nuclear subfractions (nucleoplasm, chromatin and nuclear matrix), when cells were kept at the growth temperature permissive for the expression of the transformed phenotype (32 degrees C). When tsA mutant-transformed cells were shifted to the non-permissive growth temperature (39 degrees C), they reverted to the normal phenotype. Concomitantly, large T lost its ability to associate with the cellular chromatin and the nuclear matrix, indicating that an association of large T with these subcellular structures may be important for the maintenance of cellular transformation. We next analysed the DNA-binding properties (sequence-specific binding to the SV40 origin of replication, ORI) of the nuclear subclasses of SV40 wild-type and of SV40 mutant large T defective in SV40 ORI binding in order to determine the influence of sequence-specific DNA binding on the association of large T with the chromatin and the nuclear matrix. Our detailed analyses show distinct differences in the ability of the various nuclear subclasses of large T to bind to the SV40 ORI, but suggest that the association of large T with the chromatin and the nuclear matrix is mediated by protein-protein interactions rather than by sequence-specific DNA binding.     

The HNK-1 carbohydrate epitope and the human eye in health and disease

The HNK-1 carbohydrate epitope is part of many cell membrane and extracellular matrix molecules, several of which have been implicated in cell adhesion. It is a versatile tool in eye research. In the human eye this epitope is present in the retina, the optic and ciliary nerves, the ciliary and iris epithelia, the zonular lamella, and the sciera. It is phylogenetically conserved, but the positive cell types vary from species to species. In addition to revealing interspecies differences in the vertebrate retina, the HNK-1 epitope has been used to identify a novel cell type in the eye: the subepithelial matrix cells that reside in the inner connective tissue layer (ICTL) of the ciliary body. Although these cells resemble fibroblasts in ultrastructure, they form a distinct cell population that differs in antigenic profile from fibroblasts in other tissues. The HNK-1 epitope is also associated with the elastic fiber system of the ICTL, which may be produced by the subepithelial matrix cells. It may help to structurally stabilize the ciliary body and the retina. The HNK-1 epitope is also involved in many important eye diseases. The subepithelial matrix cells seem to be susceptible to irrreversible atrophy as a result of glaucoma, thermal injury, and tissue compression. On the other hand, the HNK-1 epitope is found in the extracellular matrix of secondary cataracts and may contribute to its pathogenesis. Finally, this epitope has proved to be useful in identifying deposits of exfoliation material, and in tracing neuroepithelial derivatives in developmental anomalies and tumors of the eye.     

Autocrine stimulation in colorectal carcinoma (CRC): positive autocrine loops in human colorectal carcinoma and applicable significance of blocking the loops

Many tumors co-express growth factors and their receptors; thus, the concept of autocrine secretion was proposed to explain the unrestrained growth of the malignant cells. Autocrine stimulation refers to positive autocrine secretion, which functions to stimulate cell growth. Many of the positive autocrine loops have been demonstrated in human colorectal carcinoma (CRC), which are considered to play an important role in the initiation and progression of the cancer. These autocrine loops provide information for prognostic markers and targets for biological therapies of CRC. Interruption of the autocrine loops could potentially inhibit malignant cell growth. The field is encouraging but further research is needed.