Lectin-mediated drug targeting: preparation, binding characteristics, and antiproliferative activity of wheat germ agglutinin conjugated doxorubicin on Caco-2 cells.
OBJECTIVE
To investigate the usefulness of wheat germ agglutinin as a targeting carrier protein for an acid-labile chemotherapeutic prodrug directed against colon carcinoma cells in vitro.


METHODS
Cis-aconityl-linked doxorubicin-wheat germ agglutinin was prepared by a two step procedure and the conjugate-binding capacity of target- and non-target cells was assayed by flow cytometry. The antiproliferative activity of the prodrug on Caco-2 and MOLT-4 cells was determined by the XTT- and BrdU-test and compared with that of the parent drug and the lectin alone.


RESULTS
At pH 4.0, about 50% of the conjugated doxorubicin were released within 24 h from the water soluble prodrug exhibiting a conjugation number of 24 (mol doxorubicin/mol WGA). The prodrug-binding capacity of colon carcinoma cells exceeded that of human colonocytes and lymphoblastic MOLT-4 cells 4.5-fold. Additionally, the antiproliferative effect of the conjugate on Caco-2 cells was 39% as opposed to 5% in case of MOLT-4 cells. As the unmodified carrier protein inhibited or stimulated Caco-2 cell growth in a concentration-dependent manner, the cytostatic activity of the conjugate was determined at WGA concentrations without an effect on cell-proliferation. Considering 50% release of conjugated drug at the most, the prodrug yielded 160% of the cytostatic activity of free doxorubicin.


CONCLUSIONS
WGA-prodrug targeting offers new perspectives for site-specific, cytoinvading drug delivery in colon cancer chemotherapy.
Institute of Pharmaceutical Technology, the University of Vienna, Austria.
M
M
Wirth
A
A
Fuchs
M
M
Wolf
B
B
Ertl
F
F
Gabor
D000156:Aconitic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D000903:Antibiotics, Antineoplastic / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism*; D018938:Caco-2 Cells / Q000187:drug effects / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D002626:Chemistry, Pharmaceutical; D003106:Colon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004317:Doxorubicin / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism*; D004337:Drug Carriers; D016503:Drug Delivery Systems; D005434:Flow Cytometry; D006801:Humans; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D014909:Wheat Germ Agglutinins / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism*
D000903:Antibiotics, Antineoplastic; D004337:Drug Carriers; D014909:Wheat Germ Agglutinins; C064873:aconitic anhydride; D004317:Doxorubicin; D000156:Aconitic Acid