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Binding of epidermal growth factor and insulin-like growth-factor I in renal carcinoma and adjacent normal kidney
F Pekonen1, S Partanen, E M Rutanen
1Minerva Institute for Medical Research, Kauniainen, Finland.
Abstract:
The binding of epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) to cell membranes was determined in 14 renal cancers and in 13 normal kidney tissues adjacent to the tumors. The soluble 34K IGF binding protein (34K IGF-BP) content and the phosphotyrosyl-protein phosphatase activity in renal cancer tissue and adjacent normal tissue were also determined. The specific EGF receptor binding in renal cancers was 12.7 +/- 2.5% (mean +/- SEM) as compared to 2.6 +/- 0.2% (mean +/- SEM) in normal tissues (p less than 0.01). Phosphotyrosyl-protein phosphatase activity in renal cancer tissue was less than half of that observed in normal renal tissue (p less than 0.01). The highest IGF-I binding was observed in 5 renal cancers although no consistent differences between IGF-I binding to tumor and normal tissues were observed. Both EGF and IGF binding to kidney tissue were higher than binding to gastro-intestinal tissue irrespective of whether normal or malignant tissues were compared. All normal kidney tissues and 7 of 8 kidney tumors contained measurable amounts of 34K IGF-BP as determined by RIA and the cross-linking technique. In 2 tumor tissue samples the 34K IGF-BP content was increased 8- and 15-fold over that seen in adjacent normal kidney tissue, whereas in the 6 other renal cancers the 34K IGF-BP was similar to that observed in normal kidney tissue.
Insights
Renal cancers show significantly higher epidermal growth factor (EGF) receptor binding and lower phosphotyrosyl-protein phosphatase activity compared to normal kidney tissues. Some kidney tumors also exhibit elevated 34K IGF binding protein (IGF-BP) levels.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) play crucial roles in cell growth and differentiation.
- Alterations in growth factor receptor binding and associated protein activity are implicated in cancer development.
- Kidney cancer involves complex molecular changes affecting cell signaling pathways.
Purpose of the Study:
- To investigate the binding characteristics of EGF and IGF-I in renal cancer tissues compared to normal kidney tissues.
- To quantify the levels of 34K IGF binding protein (IGF-BP) and phosphotyrosyl-protein phosphatase activity in renal tumors.
- To explore potential molecular markers for kidney cancer diagnosis and progression.
Main Methods:
- Comparative analysis of EGF and IGF-I binding to cell membranes in 14 renal cancers and 13 adjacent normal kidney tissues.
- Quantification of soluble 34K IGF-BP using radioimmunoassay (RIA) and cross-linking techniques.
- Measurement of phosphotyrosyl-protein phosphatase activity in tumor and normal tissue samples.
Main Results:
- Specific EGF receptor binding was significantly higher in renal cancers (12.7%) than in normal tissues (2.6%) (p < 0.01).
- Phosphotyrosyl-protein phosphatase activity was less than half in renal cancer tissue compared to normal tissue (p < 0.01).
- While IGF-I binding varied, some renal cancers showed increased 34K IGF-BP levels (8- and 15-fold), though others were similar to normal tissue.
Conclusions:
- Elevated EGF receptor binding and reduced phosphotyrosyl-protein phosphatase activity are characteristic of renal cancers.
- The role of 34K IGF-BP in kidney cancer is complex, with some tumors exhibiting increased levels.
- These findings suggest potential utility of EGF receptor and IGF-BP as biomarkers in renal cell carcinoma.