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Apotransferrin is internalized and distributed in the same way as holotransferrin in K562 cells
Author(s) -
Xiulian Du,
Kui Wang,
Ya Ke,
Lan Yuan,
Rongchang Li,
Yan Zhong Chang,
Kwok Ping Ho,
Zhong Ming Qian
Publication year - 2004
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.20051
Subject(s) - transferrin , transferrin receptor , k562 cells , flow cytometry , cancer cell , microbiology and biotechnology , targeted drug delivery , pronase , chemistry , drug delivery , biology , cell , biochemistry , cancer , trypsin , genetics , organic chemistry , enzyme
Abstract Transferrin (Tf), a naturally existing protein, has received considerable attention in the area of drug targeting since it is biodegradable, non‐toxic, and non‐immunogenic. The efficient cellular uptake of Tf shows it has potential in the delivery of anti‐cancer drugs, proteins, and therapeutic genes into proliferating malignant cells that overexpress transferrin receptor (TfR). In human serum, about 30% of Tf exists in the iron‐saturated form (Fe 2 ‐Tf) and the remainder exists as apotransferrin (apo‐Tf). Understanding the uptake of apo‐Tf by cells will provide key insights into studies on Tf‐mediated drug delivery. In the present study, we investigated visually the transport of apo‐Tf into K562 cells and its intracellular localization by laser‐scanning confocal microscopy (LSCM) and flow cytometry analysis (FCA). It was found that, like Fe 2 ‐Tf, apo‐Tf can be taken up into the cells. The process is time‐ and temperature‐dependent, competitively inhibited by Fe 2 ‐Tf, and significantly abolished by pronase pretreatment. Visual evidence showed that the transport of apo‐Tf into K562 cells is a TfR‐mediated process. Furthermore, the investigations using optical‐slicing technique demonstrated that the distribution of apo‐Tf is similar to that of Fe 2 ‐Tf, both appearing in the perinuclear region in ball‐in‐bowl shape. J. Cell. Physiol. 201: 45–54, 2004. © 2004 Wiley‐Liss, Inc.