In the present study, expression and regulation of
hCG receptor mRNA were analyzed in four established human
ovarian cancer cell lines using different concentrations of hCG,
EGF, and
8-bromo-cAMP for different periods between 6 and 72 h. The cells were examined for the
hCG receptor using the
reverse-transcriptase polymerase chain reaction with specific primers amplifying the
hCG receptor gene. Receptor
mRNA was found in all cell lines. In the line OVCAR-3, it was expressed in all samples independent of kind and concentration of the receptor agonist and incubation period. In the line COLO-704, the
hCG receptor gene was expressed only in unstimulated samples, but not in the samples incubated with a receptor agonist. The cell line EFO-21 showed a downregulation of receptor
mRNA after 24 h of treatment with 25 IU/ml hCG and after 6 h of treatment with 250 IU/ml hCG or 100 ng/ml
EGF. The
mRNA reappeared within 24-48 h. The cell line EFO-27 showed a downregulation of receptor
mRNA after 6 h of incubation with 250 IU/ml hCG.
Agarose gel electrophoresis and sequencing of the polymerase chain reaction products revealed four
cDNA fragments resulting from an alternative splicing of the primary transcript. The results of the study demonstrate that the expression of
hCG receptor mRNA in
ovarian cancer cell lines varies considerably under different experimental conditions. We showed that
ovarian cancer cells can produce
hCG receptors when needed or wanted. The inherent mechanisms which rule this phenomenon need further evaluation.