[Description]:
LMP744 is a Top1 inhibitor.
[Related Catalog]:
[Target]
[In Vitro]
LMP744 (MJ-III-65) exhibits Top1 inhibition comparable with CPT with differential DNA cleavage preferences for sites 44 and 62 compare with sites 37, 97, and 119 for CPT. Fractionation of the CsCl gradient shows DNA band in fractions 7 to 10, and immunoblotting reveals the presence of Top1 signals in these DNA fractions for the LMP744- and CPT-treated cells but not in the untreated or VP-16-treated cells. LMP744 produces Top1- but not Top2-DNA cleavage complexes in cells and demonstrates that Top1 is a cellular target for LMP744. LMP744 produces DPC in a concentration-dependent manner. DPC are detectable after 1 h exposure to concentration as low as 30 nM. LMP744-mediated cell cytotoxicity is Top1-dependent at low concentrations and that LMP744 can overcome CPT resistance resulting from Top1 mutations[1].
[In Vivo]
LMP744 (MJ-III-65) shows about 65% tumor growth inhibition and delays tumor growth (increasing tumor doubling time). LMP744 is active with similar response rate against both head and neck tumor xenografts[1].
[Cell Assay]
Cytotoxicity of LMP744 (MJ-III-65) in CEM, CEM/C2, P388, and P388/CPT45 cells is measured using the MTT colorimetric assay performed in 96-well plates. Cells are seeded (6000 cells for CEM and P388 and 30,000 cells for CEM/C2 and P388/CPT45) into each well with 180 μL of RPMI 1640 medium containing 10% fetal bovine serum. Twenty microliters of LMP744 or CPT at each concentration is added to the wells, and incubations are continued for 3 days, after which 10 μL of MTT (5 mg/mL in phosphate-buffered saline) is added to each. Percentage of growth is calculated relative to control (untreated cells) after 3 days of culture with control taken as 100[1].
[Animal admin]
Thymic nude mice (nu/nu, female, 20-25 g, 8-12 weeks old) are transplanted with human head and neck xenografts. Five mice per treatment group are included in all experiments. The animals are treated with either NSC314622 (5 or 10 mg/kg/week) or LMP744 (MJ-III-65) (10, 25, or 50 mg/kg/week) administering i.v. via tail vein once a week for four consecutive weeks. The two axes (millimeters) of tumor (L, longest axis; W, shortest axis) are measured with the aid of a caliper. Tumor measurements are taken daily for the first 10 days and at least three times a week the first 3 weeks of post-therapy and once a week thereafter[1].
[References]
[Related Small Molecules]