FIBROBLAST GROWTH-FACTOR ENHANCES THE TRANSCRIPTION AND STABILITY OF HUMAN CHORIONIC-GONADOTROPIN BETA-SUBUNIT MESSENGER-RIBONUCLEIC-ACID IN JAR CHORIOCARCINOMA CELLS

In previous studies, we found that basic fibroblast growth factor (bFGF) significantly stimulated the secretion of hCGbeta in the Jar choriocarcinoma cell line. In the present study, the effect of bFGF on the steady state hCGbeta mRNA level in this cell line was determined. Application of Northern analyses with total RNA isolated from bFGF-stimulated Jar cells revealed that, in a time-dependent manner, the steady state hCGbeta mRNA level increased progressively, reaching 4-fold of the control value within 4 h after exposure to bFGF. The observed accumulation was due in part to increased transcription (2.4-fold relative to that in control cultures), as determined by nuclear transcription studies. In addition, bFGF increased the stability of the hCGbeta message; the message half-life was increased from approximately 3 h (in control cultures) to greater than 6 h (in bFGF-treated cultures). These data demonstrate that bFGF stimulates hCGbeta mRNA accumulation in a complex manner regulated through both transcriptional and posttranscriptional mechanisms.