Research On The Function And Molecular Mechanism Of Orai1-mediated Store-Operated Ca2+ Entry In Human Gastrointestinal Stromal Tumor Proliferation

ObjectiveTo investigate the effect and molecular mechanism of Orai1-mediated store-operated Ca2+ entry in human gastrointestinal stromal tumor proliferation,cell-cycle and apoptosisBackgroundGastrointestinal stromal tumors originate from interstitial cells of Cajal,the pacemaker cells of the gut.Ca2+ regulates the pacemaker activity of interstitial cells of Cajal.Store-operated Ca2+ entry mediates the majority of Ca2+ entry in most cancer cells and may be a factor in regulating intracellular Ca2+ in interstitial cells of Cajal and gastrointestinal stromal tumors.Therefore,a blockade of this mechanism may affect the progression of gastrointestinal stromal tumors.MethodsFresh GIST tissues and matched non-tumor tissues were collected from 40 pathologically confirmed GIST patients.Orai1 expression levels were detected and compared by risk categories.Then we investigated the effect of the inhibiting Orai1-mediated store-operated Ca2+ entry by Orai1 silencing or store-operated Ca2+ entry blockers(SKF-96365 and 2-APB)on GIST cell proliferation,cell-cycle and apoptosis.We also explored the function of Orai1 overexpression on GIST cell proliferation.Then we estimated the expression of c-KIT and ERK pathway by western blot ResultsOrai1 is the pore subunit of store-operated Ca2+ channels.Here,we reported that Orai1 was overexpressed in gastrointestinal stromal tumor tissues and was positively correlated with a high-risk grade in gastrointestinal stromal tumor patients.Furthermore,upon Orai1 silencing,the functional store-operated Ca2+ entry in gastrointestinal stromal tumor cells was decreased,indicating that the function of store-operated Ca2+entry was mediated by Orai1.Inhibition of Orai1-mediated store-operated Ca2+ entry by Orai1 silencing or store-operated Ca2+ entry blockers(SKF-96365 and 2-aminoethyl diphenylborate)induced obvious cell proliferation suppression,cell-cycle distribution,and apoptosis stimulation in GIST-T1 cells.Conversely,Orai1 overexpression increased store-operated Ca2+ entry and cell proliferation in GIST882 cells.In addition,we found that activation of c-KIT and the extracellular signal–regulated kinase pathway participated in the oncogenic functions of Orai1-mediated store-operated Ca2+ entry in gastrointestinal stromal tumor cells.ConclusionsThese results revealed that Orai1-mediated store-operated Ca2+ entry is critical for gastrointestinal stromal tumor cell proliferation via c-KIT and ERK signaling pathway activation.Orai1-mediated store-operated Ca2+ entry plays an oncogenic role and may be a novel prognostic factor and therapeutic target for patients with gastrointestinal stromal tumors.