Open AccessA Novel Antitumor Antibiotic, KW‐2189 Is Activated by Carboxyl Esterase and Induces DNA Strand Breaks in Human Small Cell Lung Cancer Cells
Author(s) -
Ogasawara Hayato,
Nishio Kazuto,
Takeda Yuichiro,
Ohmori Tohru,
Kubota Naohiro,
Funayama Yasunori,
Ohira Tatsuo,
Kuraishi Yasunobu,
Isogai Yukihide,
Saijo Nagahiro
Publication year - 1994
Publication title -
japanese journal of cancer research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 0910-5050
DOI - 10.1111/j.1349-7006.1994.tb02375.x
Subject(s) - agarose gel electrophoresis , dna , microbiology and biotechnology , dna damage , cytotoxicity , chemistry , biochemistry , biology , in vitro
KW‐2189 has been selected as a lead compound for clinical trial among duocarmycin derivatives with structural similarity to CC‐1065, a cyclopropylpyrroloindole. The purpose of this study was to examine the DNA‐binding potency and the mechanisms of cytotoxicity of KW‐2189. In order to analyze DNA‐binding activity of KW‐2189, plasmid pBR322 was treated with KW‐2189 with or without pretreatment with carboxyl esterase, which we demonstrated to be an activating enzyme, and the products were examined by agarose gel electrophoresis and restriction enzyme analysis. Cytotoxic activity was examined by exposing a human small cell lung cancer cell line, NCI‐H69 to KW‐2189 with or without carboxyl esterase. Alkaline elution was performed to examine whether KW‐2189 induces DNA strand breaks. DNA treated with KW‐2189 and carboxyl esterase migrated faster than KW‐2189‐treated DNA, which migrated at the same rate as untreated DNA. In addition DNA treated with esterase‐activated KW‐2189 was protected from digestion by some restriction enzymes. KW‐2189 showed concentration‐ and time‐dependent growth inhibitory effect with IC 50 values (drug concentration required for 50% growth inhibition) of 58 n M (96 h) to 1900 n M (1 h) in H69 cells. The IC 50 values of 4‐h exposure of H69 to KW‐2189 with 0, 26, 130, 650 mU/ml carboxyl esterase were 460, 120, 30, and 7 n M , respectively. Time‐dependent enhancement of cytotoxicity by carboxyl esterase was also observed. KW‐2189 induced DNA strand breaks in H69 cells in a concentration‐dependent manner around the IC 50 value. We conclude that 1) KW‐2189 is activated by carboxyl esterase to its active form(s), 2) activated KW‐2189 has a stronger DNA‐binding activity and cytotoxicity than KW‐2189, 3) DNA cleavage is one of the major mechanisms of KW‐2189‐mediated cytotoxicity.