Effect of steroids and antisteroids on human meningioma cells in primary culture.

Human meningiomas are rich in progestin receptors but virtually devoid of oestrogen receptors. We have studied the hormonal sensitivity of meningioma cells in vitro during 8 days of primary culture in the presence of different steroids and antisteroids. On day 8 the thymidine labelling index (TLI) was determined as a measure of cell growth. To date 30 cultures have been established from 39 tissue specimens. 13 cultures had a TLI below 1.0 and their growth were not affected by hormones. The TLI of the other 17 cultures was 3.0 +/- 1.7 (mean +/- SD; range 1.2-7.7). Following culture in the presence of 1 and 10 nM progesterone TLI was 83 +/- 28% (n = 9) and 61 +/- 29% (n = 3) of that of the control cultures respectively. Although in individual cultures occasional differences were found, the overall values are not statistically different from 100. Similarly, 1 nM of oestradiol and testosterone had no effect on the TLI (n = 3). Tamoxifen at 1 nM increased the TLI to 138% in one culture and decreased it to 66% of the control in another. The antiprogestin mifepristone (RU 486) in concentrations of 0.1, 1.0, 10, 100 and 1000 nM decreased the TLI to 72 +/- 30; 54 +/- 20; 55 +/- 20; 59 +/- 18 and 65 +/- 10 respectively (n = 6-15; P less than 0.05 vs control). It is concluded that although a growth promoting effect of progestins on meningioma could not be shown, the therapeutic possibilities of antiprogestins warrant further investigation.