Significance of the O6-methylguanine-DNA methyltransferase and glutathione S-transferase activity in the sera of patients with malignant and benign ovarian tumors.
OBJECTIVE
To demonstrate O6-methylguanine-DNA methyltransferase (MGMT) and glutathione S-transferase (GST) activities by analyzing the sera separately obtained from patients with malignant ovarian tumors, benign ovarian tumors, and healthy individuals.


METHODS
Fourty-nine patients with ovarian cancer, nine patients with benign tumors, and 22 healthy women were included in this study. Blood samples were obtained from all the subjects in the malignant-tumor, benign-tumor, and control groups. Patients with malignant tumors underwent second and third phlebotomies one week following the surgery and after the chemotherapy regimen, respectively. MGMT, GST, and protein levels were measured for each serum sample. GST activity of the samples was measured by the method of Habig et al. using l-chloro-2-4 dinitrobenzene (CDNB) as substrate. MGMT activity was measured by the transfer of radio labelled methyl groups from a prepared MG-DNA substrate to the enzyme fraction of serum. Protein concentration was measured by biuret method.


RESULTS
Our work demonstrated that untreated patients with malignant ovarian tumors revealed significantly greater MGMT and GST activities in their sera than did both healthy individuals and patients with benign ovarian tumors, while no significant difference was found between the healthy group and the patients with benign ovarian tumors with respect to their sera MGMT and GST activities. GST activity following chemotherapy was significantly lower than the postoperative values preceding chemotherapy. A relationship between sera MGMT and GST activities, tumor histology and pathology was not found in this study.


CONCLUSIONS
Our work suggests the fact that detection of sera MGMT and GST activities is important in diagnostic and therapeutic approaches during the course of ovarian cancer.
Akçay
Tülay
T
Division of Biochemistry, Cerrahpaşa Medical Faculty, Istanbul University, 34300 Istanbul, Turkey. tulakcay@yahoo.com
Dinçer
Yildiz
Y
Alademir
Zeynep
Z
Aydinli
Kiliç
K
Arvas
Macit
M
Demirkiran
Fuat
F
Kösebay
Derin
D
D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000097:blood*; D017024:Chemotherapy, Adjuvant; D002945:Cisplatin / Q000008:administration & dosage; D005260:Female; D005982:Glutathione Transferase / Q000097:blood*; D013509:Gynecologic Surgical Procedures; D006801:Humans; D008875:Middle Aged; D009375:Neoplasms, Glandular and Epithelial / Q000097:blood* / Q000628:therapy; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000097:blood*; D010051:Ovarian Neoplasms / Q000097:blood* / Q000628:therapy; D017239:Paclitaxel / Q000008:administration & dosage
D014408:Biomarkers, Tumor; D019853:O(6)-Methylguanine-DNA Methyltransferase; D005982:Glutathione Transferase; D017239:Paclitaxel; D002945:Cisplatin