Search

With PR81 as a murine monoclonal antibody (mAb) that was prepared against the human breast cancer, the MUC1 receptor specific targeting is possible. In this study, PR81-conjugated bovine serum albumin (BSA) nanoparticles loaded with anticancer drug 5-fluorouracil (5-FU) were developed. Enzyme linked immunosorbant assay (ELISA) results showed high immunoreactivity of PR81 mAb conjugated to nanoparticles towards MUC1 related peptide or native cancerous MUC1 and almost no cross-reaction to non-specific proteins. In vitro experiments were performed to determine the ability of this new drug delivery system on overcoming MCF-7 breast cancer cells in comparison with four other systems. The results revealed that these cell-type specific drug loaded nanoparticles could achieve more cell death as compared to when the 5-FU was used with no carriers. Stability studies of produced drug delivery system proved high immunoreactivity of conjugated PR81 even after 11 days of storage in room temperature. [ABSTRACT FROM AUTHOR]

PR81 is a monoclonal antibody that binds with high affinity to MUC1, which is over expressed on breast and other tumors. The objective of this study was to compare the two labeling methods (direct and indirect radioiodination) for application of this antibody against MUC1 as a radioimmunotherapeutical agent.Monoclonal antibody (PR81) against the tandem repeat of the core protein (MUC1) was prepared, characterized, purified, and labeled with ^{131}I using the direct (chloramin-T) and indirect (Fmoc-D-Tyr (tBu)-D-Tyr (tBu)-D-Lys (Boc)-OH (YYK) attached to N-hydroxysuccinimide as a linker between PR81 and ^{131}I) methods. The immunoreactivity of ^{131}I-PR81 and ^{131}I-TP-PR81 complexes with MUC1 (the native protein), BSA-P_{20} (a 20 amino acid corresponding the tandem repeat of MUC1) and MCF7 cell line were performed by RIA. In vitro stability of ^{131}I-PR81 and ^{131}I-YYK-peptide-PR81 complexes in human serum was determined by thin layer chromatography (TLC). Cell toxicity and in vitro internalization studies were performed with the MCF7 cell line, and the tissue biodistribution of the ^{131}I-PR81 and ^{131}I- YYK-peptide -PR81 complexes was evaluated in normal BALB/c mice at 4, 24 and 48 hrs. The labeling efficiency was determined by measuring the percentage recovery of radioactivity in the final product relative to the initial activity in the shipment vial, was found to be 59.9% ± 7.9% for direct and 50% ± 3.2% for indirect methods. ^{131}I-PR81 and ^{131}I- YYK- peptide -PR81 complexes showed high immunoreactivity towards MUC1 protein, BSA-P_{20} and MCF7 cell line. In vitro stability of the labeled products in human serum which was measured by thin layer chromatography (TLC) was found to be more than 50% over 24 hr for ^{131}I-PR81 and 70% for ^{131}I- YYK-peptide -PR81 complexes. Cell toxicity and in vitro nternalization studies showed that the ^{131}I-PR81 and ^{131}I- YYK-peptide -PR81 complexes inhibited 80% growth of the MCF7 cultured cell lines in vitro in a high concentration and up to 40% of the ^{131}I-PR81 and 60% of the ^{131}I- YYK-peptide -PR81 complexes internalized after 24 h. Biodistribution studies were performed in normal BALB/c mice at 4, 24 and 48 hrs post-injection. Thyroid and stomach levels from PR81 labeled with ^{131}I- YYK-peptide were two- to three- fold less than those with directly labeled ^{131}I-PR81, suggesting low recognition of its D-iodotyrosine residue by endogenous deiodinase. These results show that the indirect labeling was better than the indirect labeling and ^{131}I- YYK-peptide -PR81 may be considered as a promising candidate for therapy of breast cancer. [ABSTRACT FROM AUTHOR]