Absolute quantification of human chorionic gonadotropin-β mRNA with TaqMan™ detection

We describe a reverse transcriptase-polymerase chain reaction (RT-PCR) for determination of human chorionic gonadotropin-β (HCGβ) mRNA copies using the TaqMan™ system. To evaluate our quantitative assay, we analyzed HCGβ transcripts of all protein coding genes (HCGβ 5, 3, 8, and 7) in human RNA panels of different normal tissues and in glycodelin-A-stimulated trophoblast cell cultures. Absolute quantification using HCGβ TaqMan probe was found to be highly reproducible. Our study of RNA panels confirms recently published results that expression of HCGβ transcripts is a common feature of a great variety of different normal tissues. High levels of HCGβ mRNAs (>1.000 molecules per 200 ng RNA) were detected in placenta, uterus, and testis. An increase of HCGβ mRNA expression (1.7-fold) was detected at 150 µg/mL glycodelin-A treatment in trophoblast cell culture. Time-dependence study showed that the increase in HCGβ mRNA level was evident at 60 min after glycodelin-A treatment. In summary, we have developed a highly sensitive one-tube, one-enzyme quantitative RT-PCR system that is time-saving and avoids postamplification procedures.