Effect of estrogen and progesterone on gene expression of growth regulatory molecules and proto-oncogene in vascular smooth muscle cells

We examined influences of estrogen and progestogen on gene expression of th e growth regulatory molecules: platelet-derived growth factor (PDGF), inter leukin-1 (IL-1), interleukin-6 (IL-6) and proto-oncogene c-myc in vascular smooth muscle cells (VSMC) by reverse transcription-polymerase chain reacti on (RT-PCR) and Southern-blotting. VSMC were exposed to estrone-sulfate (E- 1-S) and medroxyprogesterone acetate (MPA) to induce differentiation. E-1-S inhibited the expression of PDGF-A chain, IL-1, IL-6 and c-myc mRNA, where as MPA had no effect. Inhibition by E-1-S was not affected by treatment com bined with MPA. These findings suggest that estrogen modulates these growth regulatory molecules and c-myc gene expression in VSMC but not progestogen . We concluded that estrogen may have a direct atheroprotective effect thro ugh inhibition of growth regulatory factors.