Detection of MDM2 alterations in cultured human hepatocytes treated with 17beta-estradiol or 17alpha-ethinylestradiol.
BACKGROUND
Preneoplastic and neoplastic lesions of the liver are suspected to arise as a result of estrogen treatment. Here we present the first report on the modulational effects of the steroids 17beta-estradiol (E2) and 17alpha-ethinylestradiol (EE2) on oncogene MDM2 in human hepatocytes.


METHODS
Collagen-embedded cultures of hepatocytes stimulated with different E2/EE2 concentrations were analyzed by immunocytochemistry, RT-PCR and sequencing for MDM2 protein/mRNA expression, MDM2 mRNA splicing and MDM2 gene mutation.


RESULTS
The hepatocytes responded to stimulation with steroid E2/EE2 concentrations from 1-100 nmol/l with the overexpression of MDM2 protein while non-stimulated cells were negative. Stimulation with 1 nmol/l E2 and 10-100 nmol/l EE2 induced MDM2 splicing variants. Hepatocytes treated with 100 nmol/l E2 contained full-length MDM2 mRNA carrying a new type of MDM2 gene mutation. Unstimulated hepatocytes revealed neither mRNA splicing nor alteration of the MDM2 genes.


CONCLUSIONS
The data show that steroid hormones are involved in the induction of MDM2 alterations in benign human hepatocytes. We speculate that some of the alterations may influence MDM2 function, thus possibly favouring genesis of liver changes.
Schlott
Thilo
T
Department of Cytopathology, Georg August University, Goettingen, Germany. tschlott@med.uni-goettingen.de
Thasler
Wolfgang
W
Gorzel
Carolin
C
Pahernik
Sascha
S
Brinck
Ulrich
U
Eiffert
Helmut
H
Droese
Manfred
M
D000328:Adult; D002471:Cell Transformation, Neoplastic / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004252:DNA Mutational Analysis; D004958:Estradiol / Q000494:pharmacology*; D045166:Estradiol Congeners / Q000494:pharmacology*; D004997:Ethinyl Estradiol / Q000494:pharmacology*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000139:chemically induced / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics*; D051736:Proto-Oncogene Proteins c-mdm2; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D045166:Estradiol Congeners; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D004997:Ethinyl Estradiol; D004958:Estradiol; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2