Detection of placental growth hormone variant and chorionic somatomammotropin ribonucleic acid expression in human trophoblastic neoplasms by reverse transcriptase-polymerase chain reaction

Abstract

Attempts to assess human placental GH variant (hGH-V) and chorionic somatomammotropin (hCS) RNA in choriocarcinoma cell lines have been hampered by low levels of expression and limited sensitivity of RNA blotting analysis. We examined human choriocarcinoma BeWo, JAR, and JEG-3 cell lines as well as samples of complete hydatidiform moles for expression of members of the human GH (hGH) gene family using reverse transcriptase-polymerase chain reaction. A single and common set of primers was designed and used to detect products of the hGH/hCS genes as well as distinguish processed RNA from any contaminating DNA. Transcripts from the hCS genes hCS-A and -B were distinguished from placental hGH variant (hGH-V) and hCS-like (hCS-L) gene RNA by diagnostic restriction digestion of the polymerase chain reaction products. The expected pattern of hGH/hCS RNA expression was detected in term placenta, where hCS and hGH-V/hCS-L transcripts represented approximately 95% and approximately 5% of the total hGH/hCS RNA, respectively. The level of hCS RNA varied from 22-99% of the total hGH/hCS RNA in the neoplastic trophoblast samples, and variable levels of hGH-V and hCS-L RNA were also observed. In choriocarcinoma JAR cells, hGH-V RNA represented approximately 78% of the total hGH/hCS RNA compared to approximately 22% for hCS. Further, although low hCS-L RNA levels (< 1%) were found in term placenta and two of the hydatidiform moles, hCS-L transcripts represented 11% of the total hGH/hCS RNA in a third hydatidiform mole. Finally, in contrast to the detection of variable levels of hCS-L RNA in term placenta and hydatidiform mole samples, no hCS-L transcripts were detected in the three choriocarcinoma cell lines examined. These patterns reflect either deregulated hGH/hCS gene expression in neoplastic trophoblasts or differences that accompany the process of differentiation of trophoblast subpopulations. Regardless, this suggests that the control of hGH-V and hCS-L gene expression is distinct from that of the hCS-A and hCS-B genes and raises questions about the possible involvement of hGH/hCS family members in the pathology of placental abnormalities.

Pituitary choriocarcinoma in an adolescent male: Tumor-derived CG and GH delay diagnosis

“…Furthermore, our patient's tumor probably produced GH, most likely derived from the GH2 gene. This report corroborates previous in vitro evidence [13] that choriocarcinoma cells are able to make GH-V.…”

“…We report here the case of a 17 year-old male adolescent with a choriocarcinoma found to be positive on immunohistochemistry for growth hormone (GH), and thus probably containing placental variant GH (GH-V) [12]. This is the first demonstration of GH immunostaining in a CNS choriocarcinoma, although it has previously been found in vitro in choriocarcinoma cell lines [13]. We also summarize our patient's history with a follow-up of 36 months.…”

Aspects of placental growth hormone physiology

“…Apparently, GH-V mRNA may be expressed in the absence of pit-1 [75], and in a patient with pit-1 deficiency, serum PGH levels rose steadily during pregnancy [76]. In contrast, the GH-N gene is not expressed in the placenta [72,73,77].…”

hGH-V gene expression and promoter activity under glucose and 5-azacytidine (5azaC) effects

“…The effects of different culture conditions on expression of genes from the hGH/PL locus have been demonstrated by Lytras et al (1994), Nickel and Cattini (1991), and others. We cultured JAR, JEG-3 and BeWo line cells for comparison with placenta at the end stage, to verify their ability to express hGH/PL placental genes ( Fig.…”

“…1B). The high homology shared by the five genes had caused other research groups to develop different ways to distinguish them (Lytras et al, 1994). We corroborated the PACs containing the necessary regions previously described as functionally important (Jones et al, 1995): intact and complete proximal promoter regions from hGH/PLs genes: 1.36 kb (PL-3), 1.13 kb (PL-2) and 1.1 kb (GH-V); intragenic regions (size of 591-609 pb); and enhancer regions (289 pb) for placental genes (Walker et al, 1990) (Fig.…”