Table 1.

Types of Studies that Indicate Possible Factors and Their Postulated Mechanisms that Relate to Invasiveness and Tumor Growth of Meningiomas

	Postulated Mechanisms	Types of Supporting Studies
MMP, matrix metalloproteinases; TIMP, tissue inhibitors of MMPs; PDGF, platelet-derived growth factor; EGFR, epidermal growth factor receptor; PDGFR, platelet-derived growth factor receptor.
Vascular endothelial growth factor-A (VEGF-A)	Angiogenesis and edema formation	Retrospective correlation of immunohistologic and
		—magnetic resonance images p = 0.0001,34p = 0.0575
		—microvascular density count p = 0.000575
		In vitro correlation of chemotactic activity of VEGF on endothelial cells p = 0.00350
Estrogen (E)	E receptors in 10–20% of meningiomas	Prospective immunohistological study of 57 meningiomas38
Progesterone (PR)	PR receptors in ~67% of meningiomas, especially in women	Prospective immunohistological study of 57 meningiomas38
		Northern blot and in situ hybridization analysis in nine primary human meningiomas59
Nonsteroidal hormones	Growth hormone, somatosatin, and dopamine receptors expressed in meningiomas	Review of immunohistological, in vivo, and in vitro studies76
MMPs and TIMPs	Invasiveness correlated to increase in MMP:TIMP ratio	Immunohistologic studies comparing benign and anaplastic meningiomas7,26,77
PDGF-β receptor	Autocrine growth stimulation and increase of c-fos expression	Northern blot in 20 meningiomas, measurement of exogenous PDGF-B on incubating cells of 10 meningiomas and measurement of c-fos expression11
		Comparison of astrocytomas, gliomas, and meningiomas57
Fibroblast growth factor	Angiogenesis, mitogenic	Northern blot, in situ hybridization and immunohistochemistry studies of 22 meningiomas compared with metastatic cancers and gliomas94
Ras	Transduce proliferative signals via EGFR and PDGFR	Inoculation of nine meningioma cell cultures with recombinant adenovirus Ad-rasN1790