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Pituitary macroadenomas associated with hyperprolactinaemia: immunocytochemical and in-situ hybridization studies
A M McNicol1, E Walker, M A Farquharson
1University Department of Pathology, Royal Infirmary, Glasgow, UK.
Objective:
We have assessed whether in-situ hybridization for prolactin messenger RNA (mRNA) provides additional information for the classification of pituitary macroadenomas associated with hyperprolactinaemia.
Design:
In-situ hybridization for PRL mRNA was performed on surgical biopsies of pituitary adenomas and the results correlated with serum PRL levels and PRL immunoreactivity.
Patients:
Twenty-one patients (11 men, 10 women) were included; five had normal serum PRL levels, 11 mild hyperprolactinaemia (less than 3000 mU/l) and five marked hyperprolactinaemia (greater than 3000 mU/l).
Measurements:
Immunocytochemistry for PRL and in-situ hybridization for PRL mRNA were performed on surgical biopsies.
Results:
Immunoreactivity for PRL was detected in tumours from all patients with serum PRL greater than 3000 mU/l and in one of 11 patients with mild hyperprolactinaemia. Positive signal for PRL mRNA was detected in four of five immunopositive cases studied, in a further two cases with mild hyperprolactinaemia, and in one tumour associated with normal serum PRL level.
Conclusions:
In-situ hybridization provides evidence of PRL gene activation in the absence of immunoreactivity for prolactin. This may reflect low levels of hormone storage or defective translation of the mRNA.
Insights
In-situ hybridization for prolactin messenger RNA (mRNA) detects gene activation in pituitary tumors, even without detectable prolactin protein. This technique offers new insights into pituitary macroadenoma classification and hormone production.
Area of Science:
- Endocrinology
- Molecular Biology
- Oncology
Background:
- Pituitary macroadenomas are common tumors, often associated with hyperprolactinemia.
- Accurate classification is crucial for patient management and treatment strategies.
Purpose of the Study:
- To evaluate the utility of in-situ hybridization for prolactin messenger RNA (mRNA) in classifying pituitary macroadenomas.
- To determine if this method provides additional information beyond standard prolactin (PRL) assessment.
Main Methods:
- Surgical biopsies from 21 patients with pituitary adenomas were analyzed.
- In-situ hybridization for PRL mRNA and immunocytochemistry for PRL were performed.
- Results were correlated with serum PRL levels.
Main Results:
- PRL mRNA was detected in tumors even when PRL immunoreactivity was absent.
- PRL mRNA was found in tumors associated with normal, mild, and marked hyperprolactinemia.
- In-situ hybridization identified PRL gene activation in four of five immunopositive cases and in additional cases with mild hyperprolactinemia or normal PRL levels.
Conclusions:
- In-situ hybridization for PRL mRNA offers valuable insights into pituitary macroadenomas.
- It can detect prolactin gene activation independent of detectable hormone levels.
- This technique may indicate low hormone storage or impaired mRNA translation.