Glutathione and glutathione S-transferases as early markers for ovarian carcinomas: case series.

AIM: To determine the activity of glutathione (GSH) and concentrations of glutathione S-transferases (GST), urokinase type plasminogen activator (uPA), and plasminogen activator inhibitor type 1 (PAI-1), and to evaluate their diagnostic and prognostic value and possible correlation with clinical and histopathological prognostic factors for ovarian carcinomas. METHODS: The concentrations of GSH, uPA, PAI-1, and activity of GST were analyzed in 35 tissue samples taken from 10 normal ovaries, 10 benign, 10 primary malignant, and 5 metastatic ovarian tumors. The GSH level and GST activity were determined by spectrophotometric methods, and uPA and PAI-1 concentrations by ELISA commercial kits. RESULTS: GSH concentrations were significantly higher in primary malignant (126.3+/-12.8 nmol/mg protein) and metastatic (160.5+/-24.3 nmol/mg protein) ovarian tumor specimens than in normal ovarian tissue (48.9+/-8.1 nmol/mg protein, p<0.003 for both carcinoma groups) or benign ovarian tumor samples (35.2+/-5.0 nmol/mg protein, p=0.001). The GST activity was significantly higher in primary malignant (245.8+/-22.7 nmol/min/mg protein) and metastatic (303.7+/-48.8 nmol/min/mg protein) ovarian tumor tissues than in benign tumor specimens (105.9+/-16.2 nmol/min/mg protein, p<0.004 for both carcinoma groups) or normal ovarian tissue samples (133.2+/-32.0 nmol/min/mg protein, p<0.044 for both carcinoma groups). There were no statistical differences in uPA and PAI-1 concentrations between normal, benign, and malignant tumor samples. Concentrations of GSH, uPA and PAI-1, and activity of GST were independent from histopathological and clinical prognostic factors. CONCLUSION: Increased GSH concentration and GST activity found in primary malignant and metastatic ovarian tumor samples were independent of histopathological and clinical prognostic factors, suggesting that they could be early markers for ovarian carcinomas.

Inhibition of apoptosis is the cause of resistance to doxorubicin in human breast adenocarcinoma cells.

In our previous paper we have described the isolation and characterization of a doxorubicin (DOX) resistant subline of breast adenocarcinoma SC6 cells. These cells were obtained after the treatment with low, clinically relevant doses of doxorubicin. They became cross-resistant to different wide used cytostatics. The expression of several genes involved in mitotic signal transduction, as well as cathepsins D and L, was similar in both parental and doxorubicin treated cells. The aim of this study was to examine the molecular mechanisms involved in resistance of these cells to doxorubicin. Activity of plasma membrane Pgp was examined in parental and resistant cells due to rhodamine-accumulation assay. The involvement of glutathione (GSH) and glutathione S-transferase (GST) in resistance to doxorubicin was determined in MTT modified assay due to the addition of specific inhibitors: buthionine sulfoximine (for GSH) or ethacrynic acid (for GST). The kinetic of apoptosis was followed after the treatment with DOX in control and SC6 cells by fluorescent microscope. The occurrence of apoptosis was confirmed by analysing DNA fragmentation in agarose gel. Our results indicate that P-glycoprotein, glutathione or glutathione transferases were not involved in resistance of SC6 cells to doxorubicin. However, the apoptosis was inhibited in doxorubicin-resistant cells. Therefore, even low doses of doxorubicin can induce the resistance to this drug due to inhibition of apoptosis.