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Alteration of glutathione transferase isoenzyme concentrations in human renal carcinoma
Abstract:
Glutathione transferase (GST) activity in the cytosolic fractions of four renal cortex tumors was found to be lower (1.85-3.4 times) than that present in the corresponding non-tumor cytosolic fractions. Glutathione transferase of both tumor and non-tumor kidney was purified by affinity chromatography and separated into five peaks at pH 4.7, 8.0, 8.4, 8.7 and 9.0 by isoelectric focusing. In the chromatogram of tumor tissues, the activity associated with the 'acidic' peak increased significantly, whereas the activities associated with 'basic' peaks all decreased in comparison with the corresponding peaks of non-tumor tissues. The acidic GST of human kidney is immunologically identical to GST pi, confirming that it is a good marker for human tumors.
Insights
Glutathione transferase (GST) activity is reduced in kidney tumors, with a notable increase in acidic GST forms. This acidic GST, identified as GST pi, serves as a reliable biomarker for human kidney tumors.
Area of Science:
- Biochemistry
- Oncology
- Molecular Biology
Background:
- Glutathione transferases (GSTs) are crucial enzymes involved in detoxification.
- Altered GST expression is implicated in various cancers, including renal cell carcinoma.
- Understanding specific GST isoenzyme changes in tumors is vital for biomarker development.
Purpose of the Study:
- To investigate differences in GST activity and isoenzyme profiles between human kidney tumors and non-tumor tissues.
- To identify potential GST biomarkers for renal cell carcinoma detection.
Main Methods:
- Cytosolic fractions from four renal cortex tumors and corresponding non-tumor tissues were analyzed.
- GST activity was measured.
- GST isoenzymes were purified using affinity chromatography and separated by isoelectric focusing.
- Immunological identification of the acidic GST was performed.
Main Results:
- GST activity was significantly lower in tumor tissues compared to non-tumor tissues (1.85-3.4 fold reduction).
- Isoelectric focusing revealed five distinct GST peaks in both tissue types.
- Tumor tissues showed a significant increase in activity associated with an 'acidic' GST peak.
- Activities of 'basic' GST peaks were decreased in tumor tissues.
- The acidic GST was immunologically identified as GST pi.
Conclusions:
- Kidney tumors exhibit significantly reduced overall GST activity.
- A specific acidic GST isoenzyme, GST pi, is upregulated in human kidney tumors.
- GST pi is a potential and reliable biomarker for human kidney tumors.