BACKGROUNDWith the development of antibody technology, more and more immunoconjugates are used in clinical treatment for different cancers. The aim of this study is to investigate the inhibitive effects of 5F11-DOX immunoconjugate on human lung adenocarcinoma cell line LTEP-A2 in vitro and in vivo and to explore the potential mechanism.

METHODSThe 5F11-DOX immunoconjugate was produced by diluted glutaraldehyde crosslinking. The killing efficiency of 5F11-DOX was detected by clonogenic assay. The distribution of DOX was observed under fluorescence microscope and the 5F11 location was determined by immunohistochemistry. The therapeutic efficacy of 5F11-DOX and free DOX was detected on subcutaneous or intraperitoneal exnogenic transplanted tumors of human lung adenocarcinoma A2 cells in nude mice.

RESULTS5F11-DOX of 0.04mg/L could kill all the A2 cells in vitro and the killing efficiency was 10 times as that of the free DOX. Fluorescence microscopy showed that fluorescence of DOX in 3mg/L 5F11-DOX group was much stronger than that in 3mg/L free DOX group after treating A2 cells with 3mg/L 5F11-DOX or DOX for 3h, then incubating the cells with fresh medium for another 24 hours. Immunohistochemistry showed that 5F11 located in cell membrane and cytoplasm and fluorescence microscopy proved that DOX located inside the cells. The average sizes of subcutaneous or intraperitoneal exnogenic transplanted tumors in 5F11-DOX group were obviously smaller than those of the control group and free DOX group at the same dosage (P < 0.05), and the anti-tumorogenicity efficacy of 5F11-DOX was 4-8 times as that of free DOX. The HE staining showed that extensive necrosis occurred in the center of tumors and around cancer nests in 5F11-DOX group.

CONCLUSIONSThe killing efficacy of 5F11-DOX on human lung adenocarcinoma cell line A2 is obviously higher than that of the free DOX.