Effects of dextranation on the uptake of peptides in micrometastases: studies on binding of EGF in tumor spheroids.
Four different types of radiolabelled dextranated EGF were added to spheroids consisting of the human glioma cells U-343MGaCl2:6. Binding was analysed both in the peripheral well-nourished regions and in the deeper regions containing mainly quiescent cells. The substances had different molecular weights, and they were characterized regarding hydrophilic properties and isoelectric points. Two of the analysed conjugates, 125I-EGF-dextran (CDAP) and 125I-EGF-allyldextran-BSH, gave very low 125I binding in the deeper regions even after 24 h of incubation while better binding in these regions was found for 125I-EGF-dextran-DTPA, 125I-EGF-allyldextran and for the reference substance 125I-EGF. The molecular weight seemed not to be of major importance for the binding properties and there were no clear relationships between binding and the hydrophilic properties or the isoelectric point values. The obtained differences could not be explained by differences in molecular weight or easily measured physicochemical parameters such as hydrophilic properties or isoelectric point values. Thus, other explanations must be found.
Nilsson
P
P
Biomedical Radiation Sciences, Department of Oncology, Radiology and Clinical Immunology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden.
Gedda
L
L
Sjöström
A
A
Carlsson
J
J
D001692:Biological Transport; D003911:Dextrans / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007457:Iodine Radioisotopes; D009362:Neoplasm Metastasis; D010455:Peptides / Q000378:metabolism; D018874:Spheroids, Cellular / Q000378:metabolism* / Q000473:pathology
D003911:Dextrans; D007457:Iodine Radioisotopes; D010455:Peptides; C067291:epidermal growth factor-dextran conjugate; D004815:Epidermal Growth Factor