Progesterone receptors in tumor fragment spheroids of human meningiomas

Progesterone receptors (PgR) are detectable in about 60-70% of tissue specimens of human meningiomas. Despite these data, PgR are hardly to be found in monolayer tissue culture of meningiomas. Aim of this study was to elucidate whether PgR might be preserved in tumor fragment spheroids of meningiomas maintained in organ culture since the morphological appearance of the original tumor is preserved by this culture technique. Aliquots of meningioma specimens of 25 patients (17 females) were snap frozen in liquid nitrogen immediately after removal. Additionally, monolayer tissue cultures of the same specimen were obtained as primary culture and passage #3. Tumor fragment spheroids were kept on medium-agar with liquid medium overlay and harvested after 1 and 3 weeks in culture. PgR were detected by immunohistochemistry using a rat monoclonal antibody. 18/25 meningioma tissue specimens were positive for PgR. In 8 out of 15 PgR-positive tumors which formed spheroids we could detect PgR in fragment spheroids after 1 and 3 weeks in culture. In contrast, none of the monolayers depicted PgR. PgR is preserved in a considerable amount of tumor fragment spheroids of PgR-positive meningiomas. They remain detectable after 3 weeks of culture whereas monolayer tissue cultures are PgR-negative. Thus, tumor fragment spheroids seem to be a suitable tool to investigate progesterone/antiprogesterone effects in vitro.