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Common precursor molecule as origin for the ectopic-hormone-producing-tumour syndrome
Abstract:
When messenger R.N.A. (m-R.N.A.) extracted from various hormone-secreting tumours was injected into Xenopus eggs, the translation products in all cases proved to be a protein of molecular weight 65 00. Analysis by polyacrylamide-gel electrophoresis and specific precipitation reactions with antibodies showed a striking similarity between the various proteins. When translation products of m-R.N.A. from calcitonin-secreting medullary thyroid carcinoma (M.T.C( and the non-secreting anaplastic form of M.T.C. were incubating with specific enzyme systems (the microsomal fraction) from both types of tumour, enzymes from anaplastic M.T.C. had no effect on the translation products, whereas enzymes from differentiated M.T.C. degraded the translation products from both differentiated and anaplastic M.T.C. The results support the hypothesis that the primary gene product of all the different types of carcinoma cell studied is a single large protein (a hormone precursor or prohormone) containing different specificities. The specific enzyme system in each carcinoma cell probably selects the specific hormone liberated from this primary protein.
Insights
Messenger RNA (mRNA) from hormone-secreting tumors yields a similar 65kDa protein. Differentiated tumor enzymes process this protein, supporting a common hormone precursor hypothesis in carcinomas.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- Hormone-secreting tumors present diverse clinical manifestations.
- Understanding the molecular basis of hormone production in tumors is crucial for targeted therapies.
Purpose of the Study:
- To investigate the primary gene product in various hormone-secreting carcinomas.
- To determine if a common precursor protein exists across different tumor types.
Main Methods:
- Messenger RNA (mRNA) extraction from hormone-secreting tumors.
- In vitro translation in Xenopus eggs.
- Protein analysis using polyacrylamide-gel electrophoresis and antibody precipitation.
- Enzymatic activity assays with microsomal fractions from different tumor types.
Main Results:
- Translation of tumor mRNA consistently produced a 65kDa protein.
- Proteins from different tumors showed high similarity.
- Enzymes from differentiated medullary thyroid carcinoma (MTC) degraded the protein, while those from anaplastic MTC did not.
- Differentiated MTC enzymes processed products from both differentiated and anaplastic MTC.
Conclusions:
- Carcinoma cells studied likely share a common primary gene product, a large protein precursor (prohormone).
- Specific enzymatic machinery within each carcinoma cell dictates the liberation of specific hormones from this precursor.
- This suggests a unified mechanism for hormone production in diverse carcinomas.