Therefore, new treatment strategies for glioblastomas is extremely needed. The increasing knowledge about genetic alterations that occur in glioblastomas has focused attention on development of targeted therapy which restore cell cycle or apoptosis defects in glioma cells. Therefore Selleck CX 5461 it could be an attractive alternative to conventional medicine [3–5]. Calcium (Ca2+) is a AZ 628 concentration multifunctional messenger that control many cellular
processes ranging from short-term responses such as muscle contraction and secretion to long-term regulation of cell growth and proliferation [6, 7]. Store-operated Ca2+ entry (SOCE) is a major mechanism for Ca2+ entry across the cell membrane, which is stimulated in response to depletion of Ca2+ from intracellular Ca2+ stores (primarily the
endoplasmic reticulum (ER)) and mediated via the activation of specific plasma membrane channels, termed as store-operated SBI-0206965 clinical trial channels (SOCs) . Stromal interacting molecule 1 (STIM1) is a highly conserved type-I membrane, ER-resident protein, containing a luminal EF-hand Ca2+-binding domain and several cytosolic protein-protein interaction domains, and serves a dual role as an ER Ca2+ sensor and activator of SOCE [9–11]. STIM1 initiates the process of store-operated Ca2+ influx by sensing the deletion of Ca2+ from the lumen of the ER store. It then migrates to the plasma membrane and forms aggregates at plasma membrane sites of Ca2+
entry and interacts either directly or in a complex with the plasma membrane-localized transmembrane protein Orai1 [9, 10]. The role of STIM1 in regulating cancer progression remains controversial. In early investigations which were performed prior to the discovery of its role in Ca2+ signaling, STIM1 was described as a tumor suppressor for it causes growth arrest in human G401 rhabdoid tumor cells and human RD rhabdomyosarcoma cells [12, 13]. However, subsequent studies revealed a potential role of STIM1 as an oncogene because it is up-regulated in Calpain several human cancers, such as breast cancer , glioblastoma [15, 16] and cervical cancer . Thus, more work needs to be done to fully determine the role of STIM1 in tumorigenesis which might vary in different tumor types. In the present study, we found that expression of STIM1 protein was higher in U251 and U87 glioblastoma multiforme (both Grade IV) lines than in U373 astrocytoma (Grade III), particularly higher in U251 cells . Thus, we applied lentivirus-mediated small interfering RNA (siRNA) to suppress STIM1 expression and investigated the effects of STIM1 knock down on cell proliferation and cell cycle progression in U251 cells.