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Histamine receptor 3 (H3R) is expressed in various tumors and correlated with malignancy and tumor proliferation. However, the role of H3R in tumor invasion and epithelial to mesenchymal transition (EMT) remains unknown. Here, we explored the H3R in the highly invasive glioblastoma (GBM) and U87MG cells. We found that H3R mRNA and protein levels were up-regulated in the GBM and glioma cell lines compared to normal brain tissue and astrocytes. In U87MG cell line, inhibition of H3R by siRNA or the antagonist ciproxifan (CPX) suppressed proliferation, invasiveness, and the expression of EMT activators (Snail, Slug and Twist). In addition, expression of epithelial markers (E-cadherin and ZO-1) was up-regulated and expression of mesenchymal markers (vimentin and N-cadherin) was down-regulated in vitro and in vivo in a xenograft model. In addition, we also showed that inhibition of H3R by siRNA or CPX inactivated the PI3K/Akt and MEK/ERK signaling pathways, while inhibition of Akt or ERK activity with antagonists or siRNAs suppressed H3R agonist (R)-(α)-(-)- methylhistamine dihydrobromide (RAMH) mediated invasion and reorganization of cadherin-household. In conclusion, overexpression of H3R is associated with glioma progression. Inhibition of H3R leads to suppressed invasion and EMT of GBM by inactivating the PI3K/Akt and MEK/ERK pathways in gliomas.

Epithelioid hemangioendothelioma (EHE) is a rare and low-grade vascular tumor, which usually occurs in the soft tissue, liver, breast, lung and skeleton. Here we submit a case with EHE of the clival region. A 58-year-old woman was admitted with a medical history of 3 months headache and 1 month visual deterioration. MRI revealed a well-circumscribed mass of 4.0 cm × 3.0 cm with bony invasion. The tumor was subtotally removed in a piecemeal fashion. Histologically, the tumor was composed of epithelioid cells with eosinophilic cytoplasm and intracytoplasmic vacuoles. Immunohistochemically, the tumor cells were positive for the markers CD31, CD34, factor VIII and vimentin. The pathological result was interpretated as EHE of the clival region. EHE is an uncommon vascular tumor, which is rarely seen in the clival region. Definitive diagnosis depends on histopathologic and immunohistochemical features., (© 2010 Japanese Society of Neuropathology.)