In vitro antitumor activity of MIC2 protein-doxorubicin conjugates

Simulation of the delivery of doxorubicin to hepatoma

PURPOSE

To develop a two-dimensional simulation platform for the transport of doxorubicin to the hepatoma. To examine the temporal and spatial variation of doxorubicin concentration and its penetration into the tumor and the surrounding normal tissues.

METHODS

Simulations are carried out with Fluent/UNS using the finite volume method to obtain the interstitial fluid pressure, velocity, and concentration profiles.

RESULTS

Interstitial fluid pressure in the tumor and core reaches a steady state value in about 800 s, corresponding well with the assumed time scale for interstitial matrix fluid percolation (-1,000 s). There is a strong correlation between the drug concentration in the interstitial space of tumor and blood plasma for time >> 1 h. Concentration of doxorubicin is highest in the viable zone of the tumor at early times and in the necrotic core at later times, and lowest in the surrounding normal tissues. Diffusion is the dominant form of transport for doxorubicin.

CONCLUSIONS

Varying the volume of solution injected, while keeping the dosage the same, does not cause significant changes in the amount and distribution of drug in the tumor. A higher vascular exchange area leads to higher concentrations of drug in the tumor. Lymphatic drainage in the tumor causes negligible reductions in the mean concentrations in all three different zones. Cellular metabolism and DNA binding kinetics decrease the mean concentrations of drug by about 15 to 40%, as compared to the baseline case.

Lectin-mediated drug targeting: preparation, binding characteristics, and antiproliferative activity of wheat germ agglutinin conjugated doxorubicin on Caco-2 cells

PURPOSE

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.