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Beta-Lapachone is found to inhibit the activity of topoisomerase I in a DNA unwinding assay. It inhibits the relaxation at 1μM. The potency of beta-Lapachone can be increased when pretreating topoisomerase I with beta-Lapachone for 5 min at 37°C. Beta-Lapachone is selective for topoisomerase I and shows no inhibition activity for topoisomerase II. Besides, beta-Lapachone is also proved to have no induction in topoisomerase I mediated DNA cleavage [1].
Beta-Lapachone has anti-tumor efficacy in a broad spectrum of human carcinoma cells. It induces cell death of AD2780s, HT-29, DLD, G480 and MCF-7 with IC50 values of 2μM, 5μM, 5μM, 4μM and 2μM, respectively. It is found that beta-Lapachone induces cell death of both apoptosis and necrosis through releasing cytochrome C. Beta-Lapachone is also reported to affect cell cycle. It induces primarily S-phase arrest in SW480 cells, late S- and G2/M-phase arrest in SW620 cells and early S-phase arrest in DLD1 cells [2, 3].
References:
[1] Li CJ, Averboukh L, Pardee AB. beta-Lapachone, a novel DNA topoisomerase I inhibitor with a mode of action different from camptothecin. J Biol Chem. 1993 Oct 25;268(30):22463-8.
[2] Li YZ, Li CJ, Pinto AV, Pardee AB. Release of mitochondrial cytochrome C in both apoptosis and necrosis induced by beta-lapachone in human carcinoma cells. Mol Med. 1999 Apr;5(4):232-9.
[3] Huang L, Pardee AB. beta-lapachone induces cell cycle arrest and apoptosis in human colon cancer cells. Mol Med. 1999 Nov;5(11):711-20.
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