Detection of growth hormone, prolactin and human β-chorionic gonadotropin mRNA in growth hormone-secreting pituitary adenomas and in prolactin-secreting pituitary adenomas by in situ hybridization using a non-isotopic detection method

Abstract

DK. Detection of growth hormone, prolactin and human /J-chorionic gonadotropin mRNA in growth hormone-secreting pituitary adenomas and in prolactinsecreting pituitary adenomas by in situ hybridization using a non-isotopic detection method. Acta A non-isotopic in situ hybridization method with digoxigenin-labelled probes was used to examine growth hormone (GH), prolactin (PRL) and human \g=b\-chorionicgonadotropin (\g=b\-hCG(LH))gene expression in 63 pituitary tumours in acromegaly and 20 adenomas in hyperprolactinaemia. hCG and LH were detected simultaneously because of the extensive homology (more than 90%) of their mRNA sequences (1). A comparison with former results obtained with 35S-labelled probes shows the value of the easier and faster non-isotopic method. Additionally, immunohistochemical data are included to give even more evidence for the synthesis of the respective hormones by the tumour cells. In all 63 adenomas in acromegaly, GH mRNA was revealed in 59 PRL mRNA and in 36 \g=b\-hCG(LH)mRNA. A positive immunostaining for GH was found in all, for PRL in 40, and for \g=b\-hCG(LH) in 34 adenomas. The comparison of the two in situ hybridization methods revealed no differences concerning GH mRNA detection, but not all tumours positive after non-isotopic PRL and \g=b\-hCG(LH) mRNA detection showed signals with the radioactive method. Referring to the 20 PRL-secreting adenomas, PRL gene expression was demonstrable in all, GH mRNA in 12, and \g=b\-hCG(LH)mRNA in 2 cases. Comparing the positive results of immunohistochemistry with those of in situ hybridization, correspondence was found in 19 cases for PRL, in 5 cases for GH and in no case for \g=b\-hCG(LH). W Saeger, Department of Pathologg, Marienkrankenhaus Hamburg, Alfredstr. 9, W-2000 Hamburg 76, Germany In situ hybridization (ISH) can be used for the detection of hormone mRNA in a variety of tumour cells, as shown previously by zur Hausen et al. (2), Höfler et al. (3), Hamid et al. (4), Uhlig et al. (1) and Bäz et al. (5).Furthermore, ISH is a successful means of enriching the characterization of pituitary adenomas by immunohistochemistry (IH). The simultaneous detection of a hormone-coding mRNA by ISH and the respective protein by IH can be considered as definite evidence that the hormone has been synthesized by the cell itself and not taken up from the circulation and concentrated. For many years, ISH has been performed using radioactively labelled probes guaranteeing high specific activity of probes and low detection limits, but requiring long autoradiographic exposure times and adequate facilities to handle radioactive materials. To evade these disad¬ vantages, especially in clinical or diagnostic medicine, the use of non-isotopic alternatives has been improved. As shown by Brigati et al. (6), Jirikowski et al. (7) and Kessler (8), for example, probes can be non-isotopically labelled with biotin, 5-BrdUTP or digoxigenin and detected by an immunohistochemical method. The nonradioactive ISH procedure makes it further possible to show the localization of...

Beta human chorionic gonadotropin (β-hCG) expression in pituitary adenomas: relationship to endocrine function and tumour recurrence

“…The presence of hCG in pituitary adenomas has been described previously, although the numbers of cases studied were small and varying degrees of b-hCG expression were observed [13,16,19,23]. Using in situ hybridisation techniques, Levy and co-workers described b-hCG expression in 2 of 35 (6%) pituitary adenomas [7].…”

“…The latter reports are consistent with our observations of relatively high rates of b-hCG expression in pituitary adenomas. These observations also suggest a greater sensitivity for the immunohistochemical technique in detecting b-hCG expression in pituitary adenomas [23]. Moreover, with double fluorescence labelling techniques, it has been demonstrated that the a and b-subunits of different glycoproteins are often expressed in separate adenoma cells [16].…”

Gene expression in pituitary adenomas: New insights

“…This may be from separate cell populations as in the mixed GH/PRL cell adenoma or from the same cells as in the mammosomatotroph adenoma . In situ hybridisation studies indicate that co-expression of the two genes is even more common in these two tumour types than is suggested by immunocytochemistry (Li et al, 1993;Tallen et al, 1993;Yamada et al, 1994). In a further tumour, the acidophil stem cell adenoma, GH is co-expressed with PRL although it is rarely secreted in excess .…”

“…The HCG ␤-subunit may be found in a variety of pituitary adenomas (Levy et al, 1994;Saccomanno et al, 1994;Tallen et al, 1993), but whether this has clinical relevance is unknown.…”

A PCR-Derived, non-isotopic labeled prolactin cRNA probe suitable for in situ hybridization

“…Furthermore, the RNA:RNA hybrids are more stable than the DNA:DNA hybrids ( 4 3 . The method currently available for the generation of PRL RNA probes involves in-vim transcription of double-stranded DNA templates cloned in a specific orientation into a plasmid vector carrying bacteriophage DNA-dependant RNA polymerase promoters in its sequence (6).…”