The expression of members of the IGF system in a mesothelioma from a patient suffering
from hypoglycemia, in term placenta and HT29 colon adenocarcinoma cells were compared.
Very high levels of IGF-II mRNA and protein were detected in the mesothelioma. Moreover,
half of the IGF-II protein took the high-molecular-weight form. We also analyzed the
parental imprinting status and the promoter usage of the IGF-II gene. Our results
showed loss of imprinting (LOI) in the mesothelioma while the imprinting was maintained
in HT29 cells, expressing moderate levels of the transcript. Promoter P4 was active
in the three tissues we analyzed, whereas IGF-II mRNA transcription from promoter
P3 was only detected in the mesothelioma and the placenta, expressing comparably high
levels of the transcript. IGF-II gene structure was identical in the analyzed tissues
and cells. The type-I receptor mRNA expression was very low in the tumor. IGFBP-2,
-4 and -5 mRNAs were detected in the mesothelioma, while IGFBP-2, -3 and -5 transcripts
were detected in the placenta. IGFBP-1 and -6 transcripts were not detected.
Key words
Mesothelioma - HT29 Cells - IGF-II Overexpression - IGFBPs - IGF-II Parental Imprinting
- IGF-II Promoter Usage
