Cancer biochemistry biophysics最新文献

Development of preneoplastic lesions in human lung is supposed to be accompanied with alterations of distinct biochemical features which might functionally be crucial for this alteration. To contribute to the definition of such determinants in peripheral lung parenchyma, the files of the Department of Pathology, Thoraxklinik, (a total of 2890 cases) were screened for respective tissue specimens. Seventy one cases with complete clinical documentation were found and an age-, sex-, and disease-matched control group was formed. When compared to control group patients, especially the tumor free cases with preneoplastic aberrations revealed a history of exposure to external noxes. Several probes with assumed relevance were tested with the panel of specimens for both groups, focussing on comparative analysis of alveolar lining cells. In addition to labelled neoglycoconjugates which include tissue lectin-seeking probes that expose mono-, di- and blood group-related trisaccharides, presence of calcium- and annexin-binding calcyclin, of complement component C5b, of the lymphokine macrophage migration inhibitory factor, and of ligands of the serum amyloid P component was evaluated. Compared to normal cells at the alveolar surface in controls, the preneoplastic cells displayed an apparent down-regulation of expression of A/H-trisaccharide-specific binding sites and an upregulation of expression of calcyclin. These three characteristics correlated with the phenotypic alterations and encourage further studies to elucidate the functional significance of reduced expression of the glycoligand-specific sites and the presence of this member of the S100-family of Ca(2+)-binding proteins.

Invasive properties of tumor cells having acquired heavy metal resistance were investigated. We selected the cadmium-resistant (Cd-R) cells from human fibrosarcoma HT-1080 cells. Total metallothionein levels in cytosol of HT-1080 Cd-R cells were significantly higher than original lines, and were of a highly resistant potency to cytotoxicity of cisplatin, as well as heavy metals. The HT-1080 Cd-R cells showed higher invasiveness into recombinant basement membrane Matrigel. However, HT-1080 Cd-R cells were inferior in locomotion ability. Significant differences in adhesive ability to extracellular matrix proteins were not observed between HT-1080 and HT-1080 Cd-R cells. High invasiveness of HT-1080 Cd-R cells was caused by their extremely strong enzymatic activities. High level of 92kDa matrix metalloproteinase-9 (MMP-9) was recognized from the conditioned medium of HT-1080 Cd-R cells, whereas 72kDa MMP-2 was secreted equally from both cell lines. Our investigation suggests that drug resistance acquired through the mechanisms of cellular metal-tolerance may promote malignancy and tumor metastasis during cancer chemotherapy.

The reverse micelle is one of many models thought to have properties more nearly resembling the biological cellular environment, than does the traditional dilute-solution biochemical reaction system. In order to evaluate the results of EMF perturbation of enzyme-catalyzed reactions, the description of the AOT reverse-micelle model, with respect to its internal pH, effect of chemical inhibitors, temperature, and electromagnetic-field perturbation has herein been extended. Acetylcholinesterase and NADPH cytochrome-P450 reductase, reacting within the AOT reverse-micelle, exhibit a temperature vs. activity profile equivalent to the same reaction in a buffered dilute-solution environment. In reverse micelles, some inhibitors of AChE (propidium, and d-tubocurarine) have much less effect upon indophenol-acetate hydrolysis than they do in a dilute solution environment. Other inhibitors act in the same manner within the structured environment of the reverse micelle as in the conventional dilute solution reaction model. These differences are explicable in terms of mechanism of action of the individual inhibitors. Perturbation by low-intensity microwave fields has a similar inhibitory effect upon dilute-solution reactions, as those in the 'low-water-activity' environment of the reverse micelle. However, the interactions between physical and chemical perturbants are differently limited by the structure of the aqueous phase of the reverse micelle. pH of the 'internal' reverse-micelle environment is a function of the availability of H-ions supplied by system components. Use of indicator dyes show that the low-molarity buffers which are compatible with reverse-micelle stability, are often insufficient to maintain a constant pH. Too, in the reverse micelle, reaction rate, for proton yielding reactions, is dramatically greater than the rate of the same reaction in dilute solution at the same acidic pH.

The expression of breast tumor associated mucin epitope on CAMA cell line was detected employing the mouse MAB G3F1 generated against HMFG membrane. Immunocytochemical studies revealed that MAB G3F1 strongly reacted with 85% of breast cancer tissue sections with specific staining of apical cell membrane of malignant epithelial cells. The mucin antigen recognised by MAB G3F1 was detected by selectively extracting high molecular weight glycoprotein antigen from HMFG membrane using lectin affinity chromatography and gel filtration chromatography. Immunoprecipitation studies revealed that MAB G3F1 recognized a high molecular weight glycoprotein with an approximate molecular weight of 300kd. The expression of MAB G3F1 reactive antigen on CAMA cells was detected by immunocytochemistry and by immumoprecipitating 300kd antigen from 125I labelled Tx100 solubilized extract of CAMA cells. The results from these investigations suggest that CAMA cells express MAB G3F1 reactive antigen with tumor associated epitope, similar to tumor associated mucin epitope of HMFG membrane.

Intranuclear estrogen receptor (ERn) content of breast cancer tissue is thought to be more closely related to prognosis, and response to hormone treatment, as compared to conventional cytosolic estrogen receptor (REc). ERn and ERc levels in primary breast carcinoma tissue were assayed by ER-Enzyme immuno assay (ER-EIA), and the correlation of ERn with ERc and clinico-pathological parameters were assessed. ERn concentration and positive status, with 15 fmol as the cut-off value for positivity, is related to increasing age, lesser parity, post-menopausal status and smaller tumor size. A significant correlation exists between ERn and lesser metastatic axillary nodes and the early TNM stage. ERn was found to be correlated to better tumor differentiation, absent or slight L-R response and tumor necrosis.

We demonstrated that sodium butyrate (SB) induced differentiation of functions in human hepatocellular carcinoma (HCC) cell lines. To investigate relationship between the sensitivity for cellular cytotoxicity and the cellular differentiation of HCC cells, the effect of SB on lymphokine-activated killer (LAK) sensitivity and antigen expression of a human HCC cells were studied. SB induced LAK-resistance of human HCC cell lines, HCC-T and HCC-M, time-dependently. A flowcytometric analysis of cell surface antigens revealed that SB markedly reduced the expression of laminin and fibronectin and increased the expression of liver-specific antigen defined by a mouse monoclonal antibody time-dependently, but did not modify that of major histocompatibility complex antigens, intercellular adhesion molecule (ICAM)-1, or CEA. Leukocyte function-associated antigen (LFA)-3 expression on HCC-T was reduced slightly by SB treatment. LAK sensitivity was inhibited by anti-laminin, but not with anti-beta 2-microglobulin, anti-HLA DR, anti-ICAM-1, anti-fibronectin, or anti-CEA. Anti-LFA-3 reduced LAK sensitivity of HCC-T, but not HCC-M, although the reduction was less than that obtained by anti-laminin treatment. These results provided evidence that SB induced LAK-resistance of human HCC cells according to cellular differentiation and extracellular matrix functionality played an important role in this LAK-mediated cell killing. Moreover, the structure expressed on HCC cells, which contributed to LAK cytolysis, was different for each HCC cell.

A biophysical theory is presented that supports a causal link between EMF exposures and the different biological endpoints of cancer and spontaneous abortion. The model for time-dependent instability of DNA specificity [Biochem. Genet. 32, 383 (1994)] is assumed to have been operational since DNA became selected as the molecular structure for the genome. Species were consequently required to adapt mechanisms to protect haploid gene pools from the continuous time-dependent accumulation of evolutionary base substitutions. To this end, conserved genetic domains containing mutation-intolerance thresholds are a result of natural selection operating on time-dependent base substitutions. "P53-type" genes are examples of such conserved domains with point mutation thresholds. When the oocyte is fertilized, conserved domains express wild type keto-amino genetic information. During subsequent development and growth, time-dependent evolution events populate G-C sites with enol-imine stationary states that can be transcribed and/or replicated to express transversion and transition mutations. As the level of evolution events would approach the intolerance threshold in the haploid genome, point mutation sensitive genes from conserved diploid domains, e.g. "p53-type" genes, would generate amino acid substituted proteins that have been evolutionarily selected to participate in species preservation by removing from the gene pool those haploid genomes containing advanced levels of mutation which, if propagated, would be inconsistent with survival. Consistent with the evolutionary origin of cancer hypothesis [Cancer Biochem. Biophys: 13, 147 (1993)], perturbations that would enhance rates of populating G-C sites with enol-imine states could accelerate point mutation "activation" of "p53-type" genes that could be manifested as premature cancer in living populations or expressed as spontaneous abortion in unborn populations. The evolution event "rate constant" is (gamma/h)2 where gamma is the quantum mechanical energy shift between G-C states. This expression implies that "additional" magnetic fields could increase rates of populating enol-imine states due to Lorentz force momentum transfer to metastable proton oscillators where induced electric fields and local currents would subject elevated energy proton oscillators to collisional de-exciatations which would increase the energy density of chemical bonds that support hydrogen bonds in DNA, thereby introducing larger energy shift values in (gamma/h)2. This hypothesis is explored for "additional" magnetic fields in the range of 0.15 to 0.01 gauss where the influence of magnetic enhancement energies on rates of populating enol-imine stationary states is evaluated, using Gurney and Condon tunneling time calculations for unperturbed and magnetically enhanced protons to escape metastable keto-amino energy wells. Model calculations are qualitative and are consistent with the experimentally testable hypothesis that "a

The Eighteen Annual Interdisciplinary Cancer Research Workshop was another one in a highly successful series of these New Orleans workshops. It was held on March 3, 1995, in a new location-at the J. Bennett Johnston Building of the Tulane University Medical Center. With a single exception, all the previous workshops took place at the University of New Orleans. Similarly, as all the past workshops, it was sponsored by the Cancer Association of Greater New Orleans, a United Way Agency. It was again organized by Peter Politzer (University of New Orleans), with the assistance of Anita H. Buckel (University of New Orleans) and James R. Jeter (Tulane University School of Medicine, New Orleans). The three invited speakers were William N. Hait (The Cancer Institute of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ), Joachim G. Liehr (Department of Pharmacology & Toxicology, The University of Texas Medical Branch at Galveston, Galveston, TX), and Patrice C. Ferriola (Department of Cell and Molecular Toxicology, Chemical Industry Institute of Toxicology, Research Triangle Park, NC). A one-hour discussion period after the conclusion of the last presentation represented an excellent forum for an exchange of ideas and research results among the speakers and the workshop participants. Lee Roy Morgan (Dekk-Tec, New Orleans) served as the moderator of the discussion session.

Previously we described (Dong et al., 1990) a nuclear protein (mol. wt. 112 kD) which is expressed abundantly in hepatoma cells and also in hepatocyte cells committed to carcinogenesis. In this report, we further characterize its chemical properties and cellular localization in normal and hepatoma cells. 112 kD hepatoma-associate nonhistone protein is not a cytokeratin-related protein as described by Fukuda et al. (1991). Protein purification experiments revealed that 112 kD protein is a dimer of 56 kD polypeptide present in normal rat liver nuclei. Intranuclear distribution pattern indicated that 112 kD nonhistone protein localizes exclusively in hepatoma nuclear matrix. The data from this study suggest that dimerization of 56 kD nonhistone protein is involved in nuclear matrix reorganization during neoplastic transformation.

Focal adhesion kinase (pp125FAK, FAK) is a structurally unique nonreceptor tyrosine kinase that is localized in the focal adhesion plaques. Activation or modulation of this kinase has been associated with several signaling pathways including integrin mediated processes, mitogenic stimulation by neuropeptides and platelet-derived growth factor as well as oncogene-mediated transformation. These observations suggest that FAK may play a potential role in tumorigenesis and/or tumor invasiveness. Since the phosphotyrosine content of FAK has been implicated in both the activation of its catalytic activity and the recruitment of SH2 containing proteins, the expression, phosphorylation status and enzymatic activity of FAK was examined in a number of human tumor and normal cell lines. FAK was detectable in all cell lines with fairly consistent levels of expression. In contrast, constitutive tyrosine phosphorylation of FAK was quite variable among both normal and tumor cell lines. A direct correlation (correlation coefficient = 0.94) was observed between FAK activity and phosphotyrosine content. Within the cell lines examined, colon carcinomas exhibited marked elevation in FAK tyrosine kinase activity and phosphotyrosine content. These data suggest that colon carcinomas have elevated FAK activity in comparison to other tumor types and provide further support that the catalytic activity of FAK is enhanced by its phosphotyrosine content.