Elemental Selenium Generated by the Photobleaching of Seleno-Merocyanine Photosensitizers Forms Conjugates with Serum Macro-Molecules That are Toxic to Tumor Cells

Abstract Elemental selenium generated by the photobleaching of selone photosensitizers combined with serum albumin and lipoproteins to generate conjugates that were highly cytotoxic to leukemia and selected solid tumor cells but well tolerated by normal CD34-positive hematopoietic cells. Selenium-protein conjugates were internalized by an endocytotic mechanism and localized in lysosomes. Internalized conjugates caused an extremely rapid and extensive (up to 80% in 1 hour) depletion of intracellular glutathione (GSH), the oxidation of 2′,7′-dichlorofluorescin, a loss of plasma membrane asymmetry, a breakdown of mitochondrial potential, and the activation of several caspases. Additive or synergistic anti-tumor effects were obtained when Se-protein conjugates were used in combination with ionizing radiation, melphalan, amifostine, 4-hydroperoxycyclophosphamide, edelfosine, buthionine sulfoximine, or moderate doses of arsenic (III) oxide. For example, pretreatment with a nontoxic dose of amifostine enhanced the depletion of L1210 leukemia cells from 7 log to 12 log (depletions in excess of 6 log estimated from linear extrapolations of survival curves) while the yield of normal CD34-positive cells remained at 100%. Antagonistic interactions were obtained with simultaneously applied cisplatin or very high doses of arsenic (III) oxide. The antagonistic interaction with cisplatin probably reflected a competition of cisplatin and selenium for the same binding site at or near cysteine-34 of albumin. Melphalan-resistant L1210/L-PAM1 leukemia cells (elevated intracellular GSH) were more sensitive to Se-protein conjugates than wild-type cells because of an unexpected increase in conjugate uptake by mutant cells. Cisplatin-resistant H69/CDDP cells (elevated GSH, metallothioneine, glutathione-S-transferase-pi) were slightly more sensitive than wild-type cells. Cisplatin-resistant PC14/CDDP cells (reduced drug uptake) and adriamycin-resistant HL-60/ADR cells (MRP-mediated efflux) were slightly less sensitive than the corresponding wild-type cells. In the latter cases, the reduced sensitivity of mutant tumor cells correlated with reduced conjugate uptake and/or higher intracellular GSH levels. Taken together, the above results suggest that compounds modeled after our Se-protein conjugates may prove useful for the systemic therapy of leukemia and selected solid tumors. Supported by CA77387, MACC Fund, Children’s Hospital Foundation, and Wisconsin Breast Cancer Showhouse for a Cure.

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Membranous alterations in the cytoplasm and nucleus in a primitive neuroectodermal tumor of the brain

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100084016 ◽

1978 ◽

Vol 36 (2) ◽

pp. 628-629

Author(s):

C. N. Sun ◽

C. Araoz ◽

H. J. White

Keyword(s):

Nuclear Envelope ◽

Tumor Cells ◽

Osmium Tetroxide ◽

Primitive Neuroectodermal Tumor ◽

Uranyl Acetate ◽

Neuroectodermal Tumor ◽

Annulate Lamellae ◽

Lead Citrate ◽

Thin Sections ◽

The Brain

The ultrastructure of a cerebral primitive neuroectodermal tumor has been reported previously. In the present case, we will present some unusual previously unreported membranous structures and alterations in the cytoplasm and nucleus of the tumor cells.Specimens were cut into small pieces about 1 mm3 and immediately fixed in 4% glutaraldehyde in phosphate buffer for two hours, then post-fixed in 1% buffered osmium tetroxide for one hour. After dehydration, tissues were embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate.In the cytoplasm of the tumor cells, we found paired cisternae (Fig. 1) and annulate lamellae (Fig. 2) noting that the annulate lamellae were sometimes associated with the outer nuclear envelope (Fig. 3). These membranous structures have been reported in other tumor cells. In our case, mitochondrial to nuclear envelope fusions were often noted (Fig. 4). Although this phenomenon was reported in an oncocytoma, their frequency in the present study is quite striking.

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Ulcerogenic Tumors of the Pancreas

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100100676 ◽

1968 ◽

Vol 26 ◽

pp. 186-187

Author(s):

J. C. Garancis ◽

J. F. Kuzma ◽

S. D. Wilson ◽

E. H. Ellison

Keyword(s):

Endoplasmic Reticulum ◽

Tumor Cells ◽

Islet Cell ◽

Disease Process ◽

Central Core ◽

Islet Cell Tumors ◽

Opaque Zone ◽

Granular Form ◽

Zollinger Ellison Syndrome

It has been proposed that a gastrin-like hormone elaborated by non-beta islet tumors of the pancreas may be responsible for a fulminating ulcer diathesis. Subsequently, a potent gastric secretagogue was isolated from ulcerogenic tumors of the pancreas. This disease process is known now as “Zollinger-Ellison syndrome”.In our studies of two cases of Zollinger-Ellison syndrome, pancreatic lesions were identified as alpha islet cell tumors (Fig. 1). Tumor cells were fairly uniform. The sizes of the alpha granules were not significantly different, but their number and distribution varied greatly from one cell to another. Each granule consisted of a round, highly dense central core, separated from the limiting membrane by an opaque zone. The granular form of the endoplasmic reticulum was particularly prominent. Numerous mitochondria, round or elongated, were dispersed throughout the cytoplasm. Individual or clusters of lysosomes were observed in the majority of cells.

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Glucose metabolism in cancer cells: immunogold localization of hexokinase to the outer mitochondrial membrane

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141597 ◽

1995 ◽

Vol 53 ◽

pp. 1044-1045

Author(s):

Krishan K. Arora ◽

Glenn L. Decker ◽

Peter L. Pedersen

Keyword(s):

Tumor Cells ◽

Mitochondrial Membrane ◽

Present Report ◽

Large Fraction ◽

Mitochondrial Fraction ◽

Immunogold Labeling ◽

Outer Mitochondrial Membrane ◽

Immunogold Localization ◽

Hexokinase Activity ◽

Normal Tissues

Hexokinase (ATP: D-hexose 6-phophotransferase EC 2.7.1.1) is the first enzyme of the glycolytic pathway which commits glucose to catabolism by catalyzing the phosphorylation of glucose with ATP. Previous studies have shown diat hexokinase activity is markedly elevated in rapidly growing tumor cells exhibiting high glucose catabolic rates. A large fraction (50-80%) of this enzyme activity is bound to the mitochondrial fraction (1,2) where it has preferred access to ATP (3). In contrast,the hexokinase activity of normal tissues is quite low, with one exception being brain which is a glucose-utilizing tissue (4). Biochemical evidence involving rigorous subfractionation studies have revealed striking differences between the subcellular distribution of hexokinase in normal and tumor cells [See review by Arora et al (4)].In the present report, we have utilized immunogold labeling techniques to evaluate die subcellular localization of hexokinase in highly glycolytic AS-30D hepatoma cells and in the tissue of its origin, i.e., rat liver.

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Sequential detection of mRNA for the chemokine IL-8 and macrophages (F4/80) in human melanoma

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010014141x ◽

1995 ◽

Vol 53 ◽

pp. 1008-1009

Author(s):

C.D. Bucana ◽

R. Sanchez ◽

R. Singh ◽

I.J. Fidler

Keyword(s):

Tumor Cells ◽

Nude Mice ◽

Constitutive Expression ◽

Metastatic Potential ◽

Melanoma Cells ◽

Human Melanoma ◽

Angiogenic Factor ◽

Infiltrating Cells ◽

Immunoperoxidase Assay ◽

Multifunctional Cytokine

The purpose of this study was to demonstrate by ISH the presence of IL-8 mRNA, and by immunohistochemistry (IHC) the presence of the chemokine IL-8 and the distribution of infiltrating macrophages in subcutaneous melanomas in the same tumor. IL-8 is a multifunctional cytokine produced by melanoma cells, activated macrophages and monocytes and it has been shown to be a growth and angiogenic factor for tumor cells. More recently it was shown that constitutive expression of IL-8 correlated directly with metastatic potential of human melanoma cells in nude mice. IL-8 content of a solid tumor as determined by Western blot analysis does not take into account the contribution of macrophages. Previous studies showed that murine tumors contain many infiltrating cells interspersed among tumor cells whereas human tumors growing in nude mice exhibit macrophages at the periphery or between tumor islands. In this study we demonstrate the expression of IL-8 and the distribution of macrophages by immunoperoxidase assay and IL-8 mRNA by ISH.

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Temporal and spatial interrelationships of confronting cisternae to nuclear envelope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100125051 ◽

1992 ◽

Vol 50 (1) ◽

pp. 930-931

Author(s):

John R. Palisano

Keyword(s):

Endoplasmic Reticulum ◽

Nuclear Envelope ◽

Tumor Cells ◽

Hela Cells ◽

Microscopic Investigation ◽

Electron Microscopic Investigation ◽

Serial Sections ◽

Electron Microscopic ◽

Fetal Rat ◽

Temporal And Spatial

Although confronting cistemae (CC) have been observed in a variety of tumor cells and normal fetal rat, mouse, and human epithelial tissues, little is known about their origin or role in mitotic cells. While several investigators have suggested that CC arise from nuclear envelope (NE) folding back on itself during prophase, others have suggested that CC arise when fragments of NE pair with endoplasmic reticulum. An electron microscopic investigation of 0.25 um thick serial sections was undertaken to examine the origin of CC in HeLa cells.

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