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Metabolism of steroids by human brain tumors
Abstract:
Hormonal steroids or their precursors can be metabolized in the CNS to products with altered hormonal activity. The importance of the intracerebral transformation of steroids has been demonstrated, particularly with regard to neuroendocrine regulation and sexual behavior. These studies were carried out on normal brain tissues, but the ability of neoplastic tissues of CNS origin to metabolize steroids is unknown. We investigated the in vitro metabolism of tritiated pregnenolone, testosterone, and estradiol-17 beta by homogenates of four brain tumors defined as astrocytomas. In three tumors of cortical origin, removed from adult patients, the only enzymic activity found was the conversion of estradiol to estrone. In one tumor of cerebellar origin removed from an 11-year-old boy, the following conversions were found: pregnenolone to progesterone, testosterone to either androstenedione or estradiol, and estradiol to estrone. These results demonstrate that human astrocytomas can transform steroids to compounds with modified hormonal activity. These compounds formed by the tumorous tissue can affect brain function, which may be of clinical significance. Furthermore, these results may add important parameters for biochemical characterization of neoplastic brain tissues.
Insights
Human astrocytomas can metabolize steroid hormones, altering their activity. This brain tumor steroid metabolism may impact brain function and aid in biochemical characterization.
Area of Science:
- Neuroendocrinology
- Steroid Biochemistry
- Oncology
Background:
- Steroid hormones are metabolized in the central nervous system (CNS), influencing neuroendocrine regulation and behavior.
- Previous studies focused on normal brain tissue, leaving the steroid metabolism of CNS tumors unknown.
Purpose of the Study:
- To investigate the in vitro metabolism of key steroid hormones by human astrocytoma tissues.
- To determine if neoplastic brain tissues possess the enzymatic machinery for steroid transformation.
Main Methods:
- Utilized tritiated pregnenolone, testosterone, and estradiol-17 beta.
- Analyzed steroid metabolism in homogenates from four astrocytoma samples.
- Compared metabolic activity between cortical and cerebellar astrocytomas.
Main Results:
- Cortical astrocytomas primarily converted estradiol to estrone.
- A cerebellar astrocytoma exhibited broader activity: pregnenolone to progesterone, testosterone to androstenedione or estradiol, and estradiol to estrone.
- Demonstrated enzymatic activity for steroid transformation in human astrocytomas.
Conclusions:
- Human astrocytomas possess the capability to metabolize steroid hormones into compounds with altered hormonal activity.
- Tumor-derived steroid metabolites could influence brain function, presenting potential clinical significance.
- Steroid metabolism patterns may serve as biochemical markers for characterizing brain tumors.