Speculation that
meningiomas are subject to endocrine influence is supported by their higher incidence in women, reports of exacerbation of symptoms during pregnancy, and the discovery that these
tumors harbor
progesterone- and
estrogen-
binding proteins. To evaluate if these properties could be exploited therapeutically, specimens from three convexity
meningiomas were used for
estrogen- and
progesterone-binding protein assays and establishment of tissue cultures. Each
tumor (designated A, B, and C, respectively) was grown in experimental media containing 7.5 X 10(-5) to 10(-12) M
17 beta-estradiol, 2.5 X 10(-4) to 10(-12) M
progesterone, 10(-7) to 10(-9) M
tamoxifen (an
estrogen antagonist), and 10(-6) to 10(-10) M
RU486 (a
progesterone antagonist). After incubation, cell growth was compared to control preparations by counting the
meningioma cells present in each medium.
Tumors A, B, and C contained
estrogen-
binding proteins of 8.45, 13.6, and 26.9 fmol/mg cytosol
protein and
progesterone-
binding proteins of 210, 130, and 126 fmol/mg cytosol
protein, respectively. The media containing
17 beta-estradiol and
progesterone caused 21% to 36% growth stimulation in
Tumors A and B. In
Tumor A, the addition of
tamoxifen stimulated growth by 35%, while it caused only transient stimulation in
Tumor B and had no effect on
Tumor C.
RU486, the
progesterone antagonist, caused inhibition of cell growth in all three
tumors, ranging from 18% to 36%. These data suggest that selected
meningiomas are subject to hormonal influence in vitro. The inhibition of
meningioma growth in vitro by the antiprogesterone,
RU486, has not been previously reported, and serves to encourage further development of alternative modes of
therapy for recurrent and unresectable
meningiomas.