[Value of P-glycoprotein and glutathione S-transferase-pi as chemo-resistant indicators in ovarian cancers].
OBJECTIVE
This study was conducted to assess the predictive value of P-glycoprotein (P-gp) and glutathione S-transferase-pi(GST-pi) as indicators of resistance to chemotherapy in ovarian cancers.


METHODS
Expressions of P-gp and GST-pi were immunohistochemically studied in paraffin sections from 30 normal ovaries and 74 resected specimens of primary epithelial ovarian cancer from patients who had not received any chemotherapy before surgery.


RESULTS
There were no detectable P-gp or GST-pi expression in the 30 patients with normal ovaries. In 74 cases of ovarian cancer tissue, P-gp was positive in 14 (18.9%) and GST-pi positive in 55 (74.3%) showing a highly significant correlation (P < 0.01). However, expression of P-gp and GST-pi was not associated with any of the clinicopathological parameters, such as clinical stage, histologic or tumor grade (P > 0.05). The evaluation of chemotherapy for postoperative residual ovarian cancer patients showed that all the six lesions showing P-gp positive were drug-resistant whereas only nine of the twenty-one tumors showing negative results were drug-resistant. Of 27 clinically measurable resected lesions, this difference in the response rates of the two groups was significant (P < 0.05). The predictive value of positive P-gp stain for drug resistance was 100% (6/6), and that of negative stain for objective responders was 57.1%(12/21). The response rate to chemotherapy of the GST-pi positive group (13.3%-2/15) was significantly lower than that of the SGT-pi negative group (83.3%-10/12, P < 0.01). The predictive value of positive GST-pi stain for drug resistance was 86.7%(13/15) and that of negative stain for objective responders was 83.3%(10/12). The survival rates of P-gp negative and GST-pi negative tumor patients were significantly higher than those of P-gp positive and GST-pi positive tumor patients (P < 0.01, P < 0.05, respectively).


CONCLUSIONS
These data suggest that P-gp and GST-pi expression in tumor cells are related to drug resistance in epithelial ovarian cancer. They are useful indicators of resistance to chemotherapy.
Zhang
F
F
Department of Oncology, Zhongnan Hospital, Wuhan University, Wuhan 430071, China.
Qi
L
L
Chen
H
H
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000328:Adult; D000368:Aged; D019008:Drug Resistance, Neoplasm; D005260:Female; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism*; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000401:mortality; D010053:Ovary / Q000737:chemistry / Q000473:pathology; D011237:Predictive Value of Tests; D015996:Survival Rate
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D007527:Isoenzymes; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase