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Influence of O 6 ‐methylguanine‐DNA methyltransferase activity on chloroethylnitrosourea chemotherapy in brain tumors
Author(s) -
Mineura Katsuyoshi,
Izumi Ichiro,
Watanabe Katsuo,
Kowada Masayoshi
Publication year - 1993
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910550115
Subject(s) - methyltransferase , chemotherapy , guanine , cancer research , nitrosourea , dna repair , o 6 methylguanine dna methyltransferase , brain tumor , cisplatin , dna , biology , medicine , pathology , microbiology and biotechnology , methylation , biochemistry , nucleotide , gene
Chloroethylnitrosoureas (CENUs) alkylate DNA at specific sites and inhibit DNA replication in tumor cells. O 6 ‐Alkylguanine moieties resulting from alkylation of guanine bases are thought to be one of most lethal adducts in living cells. Effectiveness of CENUs is known to relate well with an enzymic activity of the DNA repair enzyme O 6 ‐methylguanine‐DNA methyltransferase (MGMT), which recognizes and removes O 6 ‐alkylguanine. To improve therapeutic results of CENUs, we have measured MGMT activity of human brain tumors and studied the relationship between MGMT activity and clinical responsiveness to 1‐(4‐amino‐2‐methyl‐5‐pyrimidinyl)methyl‐3‐(2‐chloroethyl)‐3‐nitrosourea hydrochloride (ACNU). Thirty‐seven patients with brain tumors were entered into the study. The neoplasms included gliomas, non‐glial tumors, and brain metastases. The MGMT activity of gliomas was significantly lower than that of non‐glial tumors and brain metastases. No significant difference in the enzyme activity was noted between low‐ and high‐grade gliomas. Out of the 22 gliomas 5 tumors indicated a value below 60 fmol/mg, suggestive of a methyl excision repair minus (Mer − ) tumor. Two out of 3 evaluable patients with a Mer − tumor responded well to post‐operative ACNU adjuvant chemotherapy. Our results suggest that brain tumors include a certain percentage of Mer − phenotype tumors, and that CENUs such as ACNU should be applied selectively on tumors with a low MGMT activity in order to increase the therapeutic effectiveness. © 1993 Wiley‐Liss, Inc.