Open AccessRegulatory Network of Mitomycin C Action in Human Colon Cancer Cells
Author(s) -
Suzuki Katsuyuki,
Yamamoto Wataru,
Park JiSeon,
Hanaoka Hohken,
Okamoto Ryo,
Kirihara Yoshimasa,
Yorishima Takashi,
Okamura Tatsunori,
Kumazaki Tsutomu,
Nishiyama Masahiko
Publication year - 1999
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.1349-7006.1999.tb00785.x
Subject(s) - transfection , mitomycin c , reductase , cell culture , glutathione , microbiology and biotechnology , biology , glutathione reductase , nad+ kinase , biochemistry , enzyme , gene , genetics , glutathione peroxidase
A network composed of activation and inactivation pathways to regulate mitomycin C (MMC) action is suggested to exist in human cancer cells. COLO201 colon cancer cells were stably transfected with human NQO1 cDNA that encodes NAD(P)H: quinone oxidoreductase (DT‐diaphorase, DTD), and a clonal cell line with about 57‐fold elevated DTD activity was obtained. Northern analysis revealed that expression of the NADPH:cytochrome P450 reductase (P450 reductase) gene was decreased in the transfectant, COLO201/NQO1, associated with the increase of NQO1 expression. Biochemical characterization of the cells showed a significant increase of the glutathione (GSH) content concomitantly with the decrease of the P450 reductase activity. As a result of these coordinated modulations, sensitivity of COLO201/NQO1 to MMC was not increased as compared to the parent cells. Analyses of inhibition by specific inhibitors of DTD, P450 reductase and glutathione S ‐transferase (GST) in 5 human colon cancer cell lines including the transfectant showed that DTD and P450 reductase play significant roles in MMC activation in cells with sufficiently high DTD activity and with marginal DTD activity, respectively. In contrast, GST appeared to participate in MMC inactivation in cells with a high level of GST activity. These results indicated that DTD, P450 reductase, GSH and GST may act together compensatively or competitively, depending on their levels in cells, to determine the cellular sensitivity to MMC.