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Untersuchte Arbeit:
Seite: 24, Zeilen: 3-9, 12-22, 24-28
Quelle: Lok and Loh 1998
Seite(n): 163, 164, Zeilen: 163: 2. Spalte: 30ff; 164: 1. Spalte: 6ff
[...] oligodendrocytes are believed to be the predominant iron-containing cells in the brain and have a special requirement of iron for myelin production, and immature oligodendrocytes express TfR for iron acquisition (Connor, J.R., Menzies, S.L.et al, 1996). In normal brain, TfR immunostaining is detected primarily in endothelial and glial cells, whereas neoplastic cells from nearly all brain tumors are found to be TfR-positive (Recht, L., C.O.et al, 1990, Prior, R. et al, 1990) [...]

[...]

Most malignant and proliferating cells express high numbers of TfRs as compared to their normal and quiescent counterparts and the first direct evidence of the proliferation-associated expression of TfR was demonstrated in several lymphoblastoid cell lines and activated peripheral blood lymphocytes which have high numbers of transferrin binding sites (Larrick, J.W. et al, 1979). Subsequently, numerous reports (Kuhn, L.C. et al, 1990, Neckers, L.M. et al, 1991) confirmed that virtually all cell lines and normal proliferating cells possess high numbers of TfRs, TfR expression increases upon mitogenic stimulation and diminishes upon terminal differentiation and growth arrest and furthermore anti-TfR antibodies that can block transferrin binding and hence iron uptake inhibit cell proliferation (Trowbridge, I.S. et al, 1982). In some tumors like in breast cancers TfR has been discussed to have growth factor like functions (Cavanaugh et al 1999) which will support the notion that the TfR is a proliferation-associated marker. The explanation for the proliferation-associated expression of TfR is attributed in part to an increased requirement of iron for synthesis and functioning of numerous iron-containing proteins, in particular ribonucleotide reductase, which is a rate-limiting enzyme in DNA synthesis (Chitambar, C.R. et al, 1995).

The oligodendrocytes are believed to be the predominant iron-containing cells in the brain and have a special requirement of iron for myelin production, and immature oligodendrocytes express TfR for iron acquisition [82].

[Seite 164]

In normal brain, TfR immunostaining is detected primarily in endothelial and glial cells, whereas neoplastic cells from nearly all brain tumors are found to be TfR-positive [84, 85].

[...]

Not only tissues such as reticulocytes and placenta, but also most malignant and proliferating cells express high numbers of TfRs as compared to their normal and quiescent counterparts. The first direct evidence of the proliferation-associated expression of TfR was demonstrated in several lymphoblastoid cell lines and activated peripheral blood lymphocytes which have high numbers of transferrin binding sites [92]. Subsequently, numerous reports [93, 94] confirmed that (1) virtually all cell lines and most normal proliferating cells examined possess high numbers of TfRs, (2) TfR expression increases upon mitogenic stimulation and diminishes upon terminal differentiation and growth arrest, (3) the proliferation-associated antigens (cluster of differentiation, CD 71) present on lymphocytes are the TfR [5] and (4) anti-TfR antibodies that can block transferrin binding and hence iron uptake inhibit cell proliferation [95]. These observations, together with studies showing that iron deprivation prevents DNA synthesis [96, 97] and that transferrin is essential for in vitro cell growth in serum-free systems [98], support the notion that the TfR is a proliferation-associated marker. The explanation for the proliferation-associated expression of TfR is attributed in part to an increased requirement of iron for synthesis and functioning of numerous iron-containing proteins, in particular ribonucleotide reductase, which is a rate-limiting enzyme in DNA synthesis [99, 100].


82 Connor JR, Menzies SL: Relationship of iron to oligodendrocytes and myelination. Glia 1996;17:83–93.

84 Recht L, Torres CO, Smith TW, Raso V, Griffin TW: Transferrin receptor in normal and neoplastic brain tissue: Implications for braintumor immunotherapy. J Neurosurg 1990;72:941–945.

85 Prior R, Reifenberger G, Wechsler W: Transferrin receptor expression in tumour of the human nervous system: Relation to tumour type, grading and tumour growth fraction. Virchows Arch A Pathol Anat Histopathol 1990;416:491–496.

92 Larrick JW, Cresswell P: Modulation of cell surface iron transferrin receptors by cellular density and state of activation. J Supermol Struct 1979;11:579–586.

93 Kuhn LC, Schulman HM, Ponka P: Iron-transferrin requirements and transferrin receptor expression in proliferating cells; in Ponka, Schulman, Woodworth (eds): Iron Transport and Storage. Boca Raton, CRC Press, 1990, pp 149–191.

94 Neckers LM: Regulation of transferrin receptor expression and control of cell growth. Pathobiology 1991; 59:11–18.

95 Trowbridge IS, Lopez F: Monoclonal antibody to transferrin receptor blocks transferrin binding and inhibits human tumor cell growth in vitro. Proc Natl Acad Sci USA 1982; 79:1175–1179.

96 Hoffbrand AV, Graneshaguru K, Hooton JWL, Tattersall MHN: Effect of iron deficiency and desferrioxamine on DNA synthesis in human cells. Br J Haematol 1976;33: 517–526.

97 Fernandez-Pol JA, Bono VH Jr, Johnson GS: Control of growth by picolinic acid: Differential response of normal and transformed cells. Proc Natl Acad Sci USA 1977;74:2889–2893.

98 Barnes D, Sato G: Serum-free cell culture: A unifying approach. Cell 1980;22:649–655.

99 Eriksson S, Graslund A, Skog S, Thelander L, Tribukait B: Cell cycle- dependent regulation of mammalian ribonucleotide reductase. J Biol Chem 1984;259:11695– 11700.

100 Chitambar CR, Wereley JP: Effect of hydroxyurea on cellular iron metabolism in human leukemic CCRF-CEM cells: Changes in iron uptake and the regulation of transferrin receptor and ferritin gene expression following inhibition of DNA synthesis. Cancer Res 1995; 55:4361–4366.

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