LABORATORY INVESTIGATION - HUMAN/ANIMAL TISSUE Cerebrospinal fluid stimulates leptomeningeal and meningioma cell proliferation and activation of STAT3 Mahlon D. Johnson • Mary O’Connell • Michael Facik • Paul Maurer • Babak Jahromi • Webster Pilcher Received: 8 July 2011 / Accepted: 24 September 2011 / Published online: 5 October 2011 Ó Springer Science+Business Media, LLC. 2011 Abstract The role of cerebrospinal fluid (CSF) in the pathogenesis of meningiomas is unknown. Cell cultures from three human leptomeninges, five WHO grade I and seven grade II meningiomas were treated with remnant CSF from 22 patients with no central nervous system dis- ease and normal cell indices. Cells were evaluated by CyQUANT for DNA synthesis/cell proliferation and by western blots for phosphorylation/activation of growth regulatory pathways activated in meningiomas including JAK1–STAT3, MEK1–p44/42MAPK, Akt–mTOR and Rb. Analysis of Caspase 3 activation and survivin was also performed. Finally, the effects of PDGF neutralizing anti- body and cucurbitacin, a STAT3 inhibitor on CSF stimu- lation were tested. Compared to controls and the mitogen PDGF-BB, various CSF samples significantly stimulated DNA synthesis/cell proliferation in 20 and 22 week lep- tomeningeal cultures and all of the grade I and II menin- gioma cells tested. Collectively CSF samples, from multiple different patients, stimulated DNA synthesis in tests of 23 of 32 grade I and 18 of 28 grade II meningioma cells. CSF stimulated phosphorylation/activation of STAT3 and reduced p44/42 MAPK in the leptomeningeal, all three grade I and 1 of three grade II meningioma cells. CSF did not affect Caspase 3 activity or survivin levels. PDGF neutralizing antibody had no effect on CSF stimulation but cucurbitacin blocked PDGF and CSF stimulation. While there are limitations to the CSF available since they were not from ‘‘normal’’ volunteers, the studies suggest that, in some settings, CSF is potentially mitogenic to leptome- ningeal and meningioma cells and may act, in part, via activation of STAT3. Keywords Cerebrospinal fluid Á Meningioma Á Leptomeninges Á Growth regulation Á STAT3 Á Cucurbitacin Introduction Cerebrospinal fluid (CSF) bathes the leptomeninges and undoubtedly influences leptomeningeal development and physiology [1, 2]. However, the growth regulatory effects of CSF on the leptomeninges and meningiomas is not known. Moreover, the role of CSF in the pathogenesis of meningiomas is also unknown. Previously we have found that normal CSF stimulated proliferation of cells from a total of four WHO grade I meningiomas [3, 4]. Nonethe- less, an extensive evaluation of leptomeningeal and World Health Organization (WHO) grade I and II meningioma cells to CSF from a large number of patients of different ages has not been reported. In the present study, we evaluate the effects of human CSF on leptomeningeal and meningioma cell proliferation and activation of signaling pathways including the MAPK kinase (Raf-1)–MAP kinase/ERK kinase (MEK-1)–mitogen acti- vated protein kinase/extracellular signal regulated kinase M. D. Johnson (&) Á M. O’Connell Division of Neuropathology, Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave., Box 626, Rochester, NY 14642, USA e-mail: mahlon_johnson@urmc.rochester.edu M. Facik Division of Cytopathology, Department of Pathology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA P. Maurer Á B. Jahromi Á W. Pilcher Department of Neurosurgery, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA 123 J Neurooncol (2012) 107:121–131 DOI 10.1007/s11060-011-0736-9