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Somatostatin receptors in human endocrine tumors
Abstract:
A selection of 90 mainly endocrine but nonpituitary tumors have been tested for their content of specific somatostatin receptors using receptor autoradiography. Somatostatin receptors were detected in the following tumors: in all 5 meningiomas tested; in 3 of 39 malignant breast tumors; and in 3 growth hormone releasing factor-producing tumors, i.e., one mediastinal carcinoid, one intestinal carcinoma, and its liver metastasis. Receptor density varied greatly among individual tumors. Some of the positive tumors were biochemically characterized using in vitro binding assay and were shown to have saturable and high affinity receptors with pharmacological specificity for somatostatin. The following tumors did not contain somatostatin receptors: prostate carcinomas (n = 17); prostate hyperplasia (n = 2); ovarian carcinomas (n = 6); endometrial carcinomas (n = 4); primary liver cell carcinomas (n = 3); pheochromocytomas (n = 3); aldosteronomas (n = 2); medullary thyroid carcinomas (n = 2); one adrenocorticotropic hormone-secreting pulmonary carcinoid; one astrocytoma; one neurofibroma; one lung tumor; and one bladder tumor. Somatostatin receptors can be found in benign or malignant tumors, originating in part from tissue not primarily known as a somatostatin target. The biological function of such receptors is, therefore, partly unknown. If they can mediate antiproliferative properties, as has been suggested to be the case for somatostatin receptors in selected endocrine tumors in rats and humans, the present data could be of potential therapeutic interest.
Insights
Somatostatin receptors were found in meningiomas, breast tumors, and some endocrine tumors. Their presence in various tumor types suggests potential therapeutic applications, though their function remains partly unknown.
Area of Science:
- Endocrinology
- Oncology
- Molecular Biology
Background:
- Somatostatin receptors play a role in regulating endocrine functions.
- Their presence and function in non-endocrine tumors are not fully understood.
Purpose of the Study:
- To investigate the expression of somatostatin receptors in a variety of human tumors.
- To determine the prevalence and characteristics of somatostatin receptors in different tumor types.
Main Methods:
- Receptor autoradiography was used to screen 90 tumors for somatostatin receptors.
- In vitro binding assays were employed to characterize the identified receptors.
Main Results:
- Somatostatin receptors were detected in meningiomas, malignant breast tumors, and growth hormone-releasing factor-producing tumors (carcinoid, intestinal carcinoma).
- Receptor density varied significantly across positive tumors.
- Biochemical characterization confirmed saturable, high-affinity somatostatin receptors with specific pharmacological profiles.
- Receptors were absent in prostate, ovarian, endometrial, liver, pheochromocytoma, aldosteronoma, medullary thyroid carcinomas, and other tumor types.
Conclusions:
- Somatostatin receptors are present in diverse tumor types, including those not traditionally considered somatostatin targets.
- The findings suggest potential therapeutic roles for somatostatin receptor targeting in oncology.
- Further research is needed to elucidate the biological function of these receptors in various tumor contexts.