Differential expression of mRNA coding for heparin-binding growth factor type 2 in human cells

Area of Science:

• Cell Biology
• Molecular Biology
• Dermatology

Background:

• Cell proliferation is regulated by growth factors and serum.
• Heparin-binding growth factor type 2/basic fibroblast growth factor (HBGF-2/bFGF) is a key mitogen.
• Understanding HBGF-2/bFGF gene expression is crucial for cell growth regulation.

Purpose of the Study:

• To investigate the cellular expression of the HBGF-2/bFGF gene in normal human fibroblasts, keratinocytes, and melanocytes.
• To determine if these cell types synthesize mRNA for HBGF-2/bFGF.
• To explore the role of HBGF-2/bFGF in cell proliferation and potential paracrine mechanisms.

Main Methods:

• Studied cellular expression of the HBGF-2/bFGF gene using cDNA probes.
• Analyzed mRNA levels in fibroblasts, keratinocytes, and melanocytes.
• Investigated the effects of serum, purified growth factors, and cycloheximide on HBGF-2/bFGF gene expression.

Main Results:

• Normal human fibroblasts synthesize four distinct HBGF-2/bFGF mRNAs (7.0, 3.7, 2.2, and 1.5 kb).
• Serum treatment dramatically increased HBGF-2/bFGF mRNA levels in fibroblasts.
• Transforming growth factor-beta also increased HBGF-2/bFGF mRNA, but to a lesser extent than serum.
• Cycloheximide blocked serum-induced HBGF-2/bFGF gene expression.
• HBGF-2/bFGF mRNA was undetectable in proliferating keratinocytes, melanocytes, and mammary epithelial cells.
• A squamous cell carcinoma line (SCC-25) expressed HBGF-2/bFGF mRNA.

Conclusions:

• Fibroblasts express and regulate HBGF-2/bFGF mRNA, influenced by serum and TGF-β.
• Keratinocytes and melanocytes, which proliferate in response to bFGF, do not produce it, suggesting paracrine signaling from fibroblasts.
• HBGF-2/bFGF gene expression may be activated in some carcinomas.