FIG. 5.

Estrogen enhances invasion of thyroid cells. Matrigel-coated invasion chambers (8-μm pore membrane filters) were used for invasion assay. About 2.5 × 10⁴ cells per insert were resuspended in 500 μL medium containing 1% FBS ± 10⁻⁸ M E₂ and/or 10⁻⁶ M fulvestrant were transferred onto the upper surface of filters in the chamber. Seven hundred and fifty microliters of growth medium containing 5% FBS was used as chemoattractant. Invasion was calculated based on the percent of cells invading through the growth-factor-reduced Matrigel invasion chambers relative to the cells migrating through control membrane after 18 hours when counted under 10 × field. The groups are as follows: untreated (white bars), E₂ treated (black bars), and E₂ + fulvestrant treated (gray bars). MCF-7 was used as a positive control for invasion. Data are represented as percent invasion (according to manufacturer's protocol), which is mean number of invaded cells per 10 × field micrograph for each sample well relative to the migration through the control membrane and normalized to the untreated control. * denotes statistically significant differences (p < 0.05) between experimental and control groups.