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Studies on cyclic nucleotides in cancer. I. Adenylate guanylate cyclase and protein kinases in the prostatic sarcoma
Abstract:
Adenylate, guanylate cyclase and protein kinases in a fibrous sarcoma originating from rat prostate have been studied. A decrease in levels of adenosine 3', 5'-monophosphate (cyclic AMP) and adenylate cyclase activities and an increase in levels of guanosine 3',5'-monophosphate (cyclic GMP) and guanylate cyclase activities were observed in the tumor tissue when compared with the normal prostatic tissue of rats. Protein kinases from the tumor and the prostate were both responsive to exogenous cyclic AMP, with an apparent Ka of 0.08 muM in the tumor and of 0.11 muM in the prostate. It is of interest that the protein kinases from the tumor responded to cyclic AMP to the same extent as was observed in the enzyme preparation from the prostate. The protein kinase from the tumor was more sensitive to cyclic GMP than that from the prostate, showing an apparent Ka of 0.88 muM in the tumor and of 4.85 muM in the prostate. This tumor has been characterized with an increase in guanylate cyclase activities with a subsequent rise in cellular cyclic GMP and an increased sensitivity of the protein kinase to cyclic GMP.
Insights
Rat prostate tumors show decreased cyclic AMP and increased cyclic GMP levels. Protein kinases in the tumor exhibit heightened sensitivity to cyclic GMP, suggesting altered signaling pathways in cancer development.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- Prostate cancer involves alterations in intracellular signaling pathways.
- Cyclic nucleotides like cyclic AMP and cyclic GMP play crucial roles in cellular regulation.
- Understanding enzyme activities in tumor tissue is vital for cancer research.
Purpose of the Study:
- To investigate the activities of adenylate cyclase, guanylate cyclase, and protein kinases in rat prostate fibrous sarcoma.
- To compare these enzyme activities and cyclic nucleotide levels between tumor tissue and normal prostate tissue.
- To assess the sensitivity of protein kinases to cyclic AMP and cyclic GMP in both normal and cancerous prostate tissue.
Main Methods:
- Enzyme activity assays for adenylate cyclase and guanylate cyclase.
- Measurement of cyclic AMP and cyclic GMP levels.
- Characterization of protein kinase response to cyclic nucleotides using apparent dissociation constants (Ka).
- Comparative analysis between tumor and normal prostate tissue.
Main Results:
- Tumor tissue exhibited decreased adenylate cyclase activity and cyclic AMP levels compared to normal prostate tissue.
- Tumor tissue showed increased guanylate cyclase activity and cyclic GMP levels.
- Protein kinases from both tumor and normal prostate were responsive to cyclic AMP.
- Tumor-derived protein kinases demonstrated significantly higher sensitivity to cyclic GMP than those from normal prostate tissue.
Conclusions:
- Rat prostate fibrous sarcoma is characterized by altered cyclic nucleotide metabolism, with increased guanylate cyclase activity and cyclic GMP levels.
- The enhanced sensitivity of tumor protein kinases to cyclic GMP suggests a potential role in the tumor's aberrant signaling.
- These findings highlight key biochemical differences in signaling pathways between normal and cancerous prostate tissue.