The WHO grade (2007 classification), Ki67-MIB1, progesterone receptor expression, and histological subtype were reexamined and correlated to the meningioma location, classified as medial skull base, lateral skull base, non-skull base, and spinal.
Meningiomas are more common in females and 70-80% express the progesterone receptor, raising the possibility that high-dose exogenous estrogen/progesterone exposure, such as occurs during fertility treatments, may increase the risk of developing a meningioma.
Significant association between lower expression of PR (OR 11.7; 95% CI 4.17-32.9; <i>P</i> < 0.001 comparing the lowest quartile vs. 3 highest quartile of PR) and <i>NF2</i> (OR 4.23; 95% CI 1.85-9.67; <i>P</i> = 0.001 comparing the 2 lowest quartiles vs. 2 highest quartiles) with increased risk of meningioma were also reported.
In the clinical samples of meningioma, the levels of cathepsins B and L, stefin B, and cystatin C were highest in the tumors of higher histological grades, whereas stefin A and progesterone receptor were the only markers that were significantly increased and decreased, respectively, in WHO Grade III lesions.
An increase in transcription was observed with the addition of promegestone (R5020), a progesterone agonist, only in meningioma cell cultures that were expressing the progesterone receptor.
These data suggest that progesterone receptor mRNA and protein is expressed in meningiomas and support the concept that progesterone may play an important role in meningioma growth.
Within the confines of this study, it is concluded that: 1) the estrogen receptor is generally absent in meningioma tissue, and 2) the progesterone receptor is mainly absent in the nuclear compartment, leading to the conclusion that the cytosolic progesterone receptor may be an inactive form.